[master] Imported from libpng-1.6.21.tar

[master] Imported from libpng-1.6.20.tar
[master] Imported from libpng-1.6.19.tar
2025-07-10 18:04:09 +02:00 · 2016-01-15 14:04:53 -06:00 · 2015-12-02 22:37:04 -06:00 · 2015-11-12 07:18:03 -06:00 · 2015-07-22 22:41:05 -05:00 · 2015-03-26 08:11:22 -05:00
81 changed files with 1785 additions and 8778 deletions
--- a/53
+++ b/53
@@ -1,4 +1,4 @@
-Libpng 1.6.25 - September 1, 2016
+Libpng 1.6.21 - January 15, 2016

 This is a public release of libpng, intended for use in production codes.

@@ -7,30 +7,51 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   libpng-1.6.25.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.25.tar.gz
+   libpng-1.6.21.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.21.tar.gz

 Source files with CRLF line endings (for Windows), without the
 "configure" script

-   lpng1625.7z  (LZMA-compressed, recommended)
-   lpng1625.zip
+   /scratch/glennrp/Libpng16/lpng1621.7z  (LZMA-compressed, recommended)
+   /scratch/glennrp/Libpng16/lpng1621.zip

 Other information:

-   libpng-1.6.25-README.txt
-   libpng-1.6.25-LICENSE.txt
-   libpng-1.6.25-*.asc (armored detached GPG signatures)
+   libpng-1.6.21-README.txt
+   libpng-1.6.21-LICENSE.txt
+   libpng-1.6.21-*.asc (armored detached GPG signatures)

-Changes since the last public release (1.6.24):
-  Reject oversized iCCP profile immediately.
-  Cleaned up PNG_DEBUG compile of pngtest.c.
-  Conditionally compile png_inflate().
-  Don't install pngcp; it conflicts with pngcp in the pngtools package.
-  Minor editing of INSTALL, (whitespace, added copyright line)
-  Added MIPS support (Mandar Sahastrabuddhe <Mandar.Sahastrabuddhe@imgtec.com>).
-  Rebased contrib/intel/intel_sse.patch after the MIPS implementation.
+Changes since the last public release (1.6.20):

+  Fixed syntax "$(command)" in tests/pngstest that some shells other than
+    bash could not parse (Bug report by Nelson Beebe). Use `command` instead.
+  Moved png_check_keyword() from pngwutil.c to pngset.c
+  Removed LE/BE dependencies in pngvalid, to 'fix' the current problem
+    in the BigEndian tests by not testing it, making the BE code the same 
+    as the LE version.
+  Fixes to pngvalid for various reduced build configurations (eliminate unused
+    statics) and a fix for the case in rgb_to_gray when the digitize option
+    reduces graylo to 0, producing a large error.
+  Widened the 'limit' check on the internally calculated error limits in
+    the 'DIGITIZE' case (the code used prior to 1.7 for rgb_to_gray error
+    checks) and changed the check to only operate in non-release builds
+   (base build type not RC or RELEASE.)
+  Fixed undefined behavior in pngvalid.c, undefined because
+    (png_byte) << shift is undefined if it changes the signed bit
+    (because png_byte is promoted to int). The libpng exported functions
+    png_get_uint_32 and png_get_uint_16 handle this. (Bug reported by
+    David Drysdale as a result of reports from UBSAN in clang 3.8).
+  This changes pngvalid to use BE random numbers; this used to produce
+    errors but these should not be fixed as a result of the previous changes.
+  In projects/vstudio, combined readme.txt and WARNING into README.txt
+  Relocated assert() in contrib/tools/pngfix.c, bug found by American
+    Fuzzy Lop, reported by Brian Carpenter.
+  Marked 'limit' UNUSED in transform_range_check().  This only affects
+    release builds.
+  Worked around a false-positive Coverity issue in pngvalid.c.
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe)
--- a/221
+++ b/221
@@ -5063,8 +5063,7 @@ Version 1.6.15beta04 [November 4, 2014]
 Version 1.6.15beta05 [November 5, 2014]
  Use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING in
    example.c, pngtest.c, and applications in the contrib directory.
-  Fixed an out-of-range read in png_user_version_check() (Bug report from
-    Qixue Xiao, CVE-2015-8540).
+  Avoid out-of-bounds memory access in png_user_version_check().
  Simplified and future-proofed png_user_version_check().
  Fixed GCC unsigned int->float warnings. Various versions of GCC
    seem to generate warnings when an unsigned value is implicitly
@@ -5485,224 +5484,6 @@ Version 1.6.21rc02 [January 7, 2016]
 Version 1.6.21 [January 15, 2016]
  Worked around a false-positive Coverity issue in pngvalid.c.

-Version 1.6.22beta01 [January 23, 2016]
-  Changed PNG_USE_MKSTEMP to __COVERITY__ to select alternate
-    "tmpfile()" implementation in contrib/libtests/pngstest.c
-  Fixed NO_STDIO build of pngunknown.c to skip calling png_init_io()
-    if there is no stdio.h support.
-  Added a png_image_write_to_memory() API and a number of assist macros
-    to allow an application that uses the simplified API write to bypass
-    stdio and write directly to memory.
-  Added some warnings (png.h) and some check code to detect *possible*
-    overflow in the ROW_STRIDE and simplified image SIZE macros.  This
-    disallows image width/height/format that *might* overflow.  This is
-    a quiet API change that limits in-memory image size (uncompressed) to
-    less than 4GByte and image row size (stride) to less than 2GByte.
-  Revised workaround for false-positive Coverity issue in pngvalid.c.
-
-Version 1.6.22beta02 [February 8, 2016]
-  Only use exit(77) in configure builds.
-  Corrected error in PNG_IMAGE_PNG_SIZE_MAX. This new macro underreported
-    the palette size because it failed to take into account that the memory
-    palette has to be expanded to full RGB when it is written to PNG.
-  Updated CMakeLists.txt, added supporting scripts/gen*.cmake.in
-    and test.cmake.in (Roger Leigh).
-  Relaxed limit checks on gamma values in pngrtran.c. As suggested in
-    the comments gamma values outside the range currently permitted
-    by png_set_alpha_mode are useful for HDR data encoding.  These values
-    are already permitted by png_set_gamma so it is reasonable caution to
-    extend the png_set_alpha_mode range as HDR imaging systems are starting
-    to emerge.
-
-Version 1.6.22beta03 [March 9, 2016]
-  Added a common-law trademark notice and export control information
-    to the LICENSE file, png.h, and the man page.
-  Restored "& 0xff" in png_save_uint_16() and png_save_uint_32() that
-    were accidentally removed from libpng-1.6.17. 
-  Changed PNG_INFO_cHNK and PNG_FREE_cHNK from 0xnnnn to 0xnnnnU in png.h
-    (Robert C. Seacord).
-  Removed dubious "#if INT_MAX" test from png.h that was added to
-    libpng-1.6.19beta02 (John Bowler).
-  Add ${INCLUDES} in scripts/genout.cmake.in (Bug report by Nixon Kwok).
-  Updated LICENSE to say files in the contrib directory are not
-    necessarily under the libpng license, and that some makefiles have
-    other copyright owners.
-  Added INTEL-SSE2 support (Mike Klein and Matt Sarett, Google, Inc.).
-  Made contrib/libtests/timepng more robust.  The code no longer gives
-    up/fails on invalid PNG data, it just skips it (with error messages).
-    The code no longer fails on PNG files with data beyond IEND.  Options
-    exist to use png_read_png (reading the whole image, not by row) and, in
-    that case, to apply any of the supported transforms.  This makes for
-    more realistic testing; the decoded data actually gets used in a
-    meaningful fashion (John Bowler).
-  Fixed some misleading indentation (Krishnaraj Bhat).
-
-Version 1.6.22beta04 [April 5, 2016]
-  Force GCC compilation to C89 if needed (Dagobert Michelsen).
-  SSE filter speed improvements for bpp=3:
-    memcpy-free implementations of load3() / store3().
-    call load3() only when needed at the end of a scanline.
-
-Version 1.6.22beta05 [April 27, 2016]
-  Added PNG_FAST_FILTERS macro (defined as
-    PNG_FILTER_NONE|PNG_FILTER_SUB|PNG_FILTER_UP).
-  Various fixes for contrib/libtests/timepng.c
-  Moved INTEL-SSE code from pngpriv.h into contrib/intel/intel_sse.patch.
-  Fixed typo (missing underscore) in #define PNG_READ_16_TO_8_SUPPORTED
-    (Bug report by Y.Ohashik).
-
-Version 1.6.22beta06 [May 5, 2016]
-  Rebased contrib/intel_sse.patch.
-  Quieted two Coverity issues in contrib/libtests/timepng.c.
-  Fixed issues with scripts/genout.cmake.in (David Capello, Nixon Kwok):
-    Added support to use multiple directories in ZLIBINCDIR variable,
-    Fixed CMAKE_C_FLAGS with multiple values when genout is compiled on MSVC,
-    Fixed pnglibconf.c compilation on OS X including the sysroot path.
-
-Version 1.6.22rc01 [May 14, 2016]
-  No changes.
-
-Version 1.6.22rc02 [May 16, 2016]
-  Removed contrib/timepng from default build; it does not build on platforms
-    that don't supply clock_gettime().
-
-Version 1.6.22rc03 [May 17, 2016]
-  Restored contrib/timepng to default build but check for the presence
-    of clock_gettime() in configure.ac and Makefile.am.
-
-Version 1.6.22 [May 26, 2016]
-  No changes.
-
-Version 1.6.23beta01 [May 29, 2016]
-  Stop a potential memory leak in png_set_tRNS() (Bug report by Ted Ying).
-  Fixed the progressive reader to handle empty first IDAT chunk properly
-    (patch by Timothy Nikkel).  This bug was introduced in libpng-1.6.0 and
-    only affected the libpng16 branch.
-  Added tests in pngvalid.c to check zero-length IDAT chunks in various
-    positions.  Fixed the sequential reader to handle these more robustly
-    (John Bowler).
-
-Version 1.6.23rc01 [June 2, 2016]
-  Corrected progressive read input buffer in pngvalid.c. The previous version
-    the code invariably passed just one byte at a time to libpng.  The intent
-    was to pass a random number of bytes in the range 0..511.
-  Moved sse2 prototype from pngpriv.h to contrib/intel/intel_sse.patch.
-  Added missing ")" in pngerror.c (Matt Sarrett).
-
-Version 1.6.23rc02 [June 4, 2016]
-  Fixed undefined behavior in png_push_save_buffer(). Do not call
-    memcpy() with a null source, even if count is zero (Leon Scroggins III).
-
-Version 1.6.23 [June 9, 2016]
-  Fixed bad link to RFC2083 in png.5 (Nikola Forro).
-
-Version 1.6.24beta01 [June 11, 2016]
-  Avoid potential overflow of the PNG_IMAGE_SIZE macro.  This macro
-    is not used within libpng, but is used in some of the examples.
-
-Version 1.6.24beta02 [June 23, 2016]
-  Correct filter heuristic overflow handling. This was broken when the
-    write filter code was moved out-of-line; if there is a single filter and
-    the heuristic sum overflows the calculation of the filtered line is not
-    completed.  In versions prior to 1.6 the code was duplicated in-line
-    and the check not performed, so the filter operation completed; however,
-    in the multi-filter case where the sum is performed the 'none' filter would
-    be selected if all the sums overflowed, even if it wasn't in the filter
-    list.  The fix to the first problem is simply to provide PNG_SIZE_MAX as
-    the current lmins sum value; this means the sum can never exceed it and
-    overflows silently.  A reasonable compiler that does choose to inline
-    the code will simply eliminate the sum check.
-  The fix to the second problem is to use high precision arithmetic (this is
-    implemented in 1.7), however a simple safe fix here is to chose the lowest
-    numbered filter in the list from png_set_filter (this only works if the
-    first problem is also fixed) (John Bowler).
-  Use a more efficient absolute value calculation on SSE2 (Matthieu Darbois).
-  Fixed the case where PNG_IMAGE_BUFFER_SIZE can overflow in the application
-    as a result of the application using an increased 'row_stride'; previously
-    png_image_finish_read only checked for overflow on the base calculation of
-    components.  (I.e. it checked for overflow of a 32-bit number on the total
-    number of pixel components in the output format, not the possibly padded row
-    length and not the number of bytes, which for linear formats is twice the
-    number of components.)
-  MSVC does not like '-(unsigned)', so replaced it with 0U-(unsigned)
-  MSVC does not like (uInt) = -(unsigned) (i.e. as an initializer), unless
-    the conversion is explicitly invoked by a cast.
-  Put the SKIP definition in the correct place. It needs to come after the
-    png.h include (see all the other .c files in contrib/libtests) because it
-    depends on PNG_LIBPNG_VER.
-  Removed the three compile warning options from the individual project
-    files into the zlib.props globals.  It increases the warning level from 4
-    to All and adds a list of the warnings that need to be turned off.  This is
-    semi-documentary; the intent is to tell libpng users which warnings have
-    been examined and judged non-fixable at present.  The warning about
-    structure padding is fixable, but it would be a signficant change (moving
-    structure members around).
-
-Version 1.6.24beta03 [July 4, 2016]
-  Optimized absolute value calculation in filter selection, similar to
-    code in the PAETH decoder in pngrutil.c. Build with PNG_USE_ABS to
-    use this.
-  Added pngcp to the build together with a pngcp.dfa configuration test.
-  Added high resolution timing to pngcp.
-  Added "Common linking failures" section to INSTALL.
-  Relocated misplaced #endif in png.c sRGB profile checking.
-  Fixed two Coverity issues in pngcp.c.
-
-Version 1.6.24beta04 [July 8, 2016]
-  Avoid filter-selection heuristic sum calculations in cases where only one
-    filter is a candidate for selection. This trades off code size (added
-    private png_setup_*_row_only() functions) for speed.
-
-Version 1.6.24beta05 [July 13, 2016]
-  Fixed some indentation to comply with our coding style.
-  Added contrib/tools/reindent.
-
-Version 1.6.24beta06 [July 18, 2016]
-  Fixed more indentation to comply with our coding style.
-  Eliminated unnecessary tests of boolean png_isaligned() vs 0.
-
-Version 1.6.24rc01 [July 25, 2016]
-  No changes.
-
-Version 1.6.24rc02 [August 1, 2016]
-  Conditionally compile SSE2 headers in contrib/intel/intel_sse.patch
-  Conditionally compile png_decompress_chunk().
-
-Version 1.6.24rc03 [August 2, 2016]
-  Conditionally compile ARM_NEON headers in pngpriv.h
-  Updated contrib/intel/intel_sse.patch
-
-Version 1.6.24[August 4, 2016]
-  No changes.
-
-Version 1.6.25beta01 [August 12, 2016]
-  Reject oversized iCCP profile immediately.
-  Cleaned up PNG_DEBUG compile of pngtest.c.
-  Conditionally compile png_inflate().
-
-Version 1.6.25beta02 [August 18, 2016]
-  Don't install pngcp; it conflicts with pngcp in the pngtools package.
-  Minor editing of INSTALL, (whitespace, added copyright line)
-
-Version 1.6.25rc01 [August 24, 2016]
-  No changes.
-
-Version 1.6.25rc02 [August 29, 2016]
-  Added MIPS support (Mandar Sahastrabuddhe <Mandar.Sahastrabuddhe@imgtec.com>).
-  Only the UP filter is currently implemented.
-
-Version 1.6.25rc03 [August 29, 2016]
-  Rebased contrib/intel/intel_sse.patch after the MIPS implementation.
-
-Version 1.6.25rc04 [August 30, 2016]
-  Added MIPS support for SUB, AVG, and PAETH filters (Mandar Sahastrabuddhe).
-
-Version 1.6.25rc05 [August 30, 2016]
-  Rebased contrib/intel/intel_sse.patch after the MIPS implementation update..
-
-Version 1.6.25 [September 1, 2016]
-  No changes.
-
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,32 +1,13 @@
 # CMakeLists.txt

-# Copyright (C) 2007,2009-2016 Glenn Randers-Pehrson
-# Written by Christian Ehrlicher, 2007
-# Revised by Roger Lowman, 2009-2010
-# Revised by Clifford Yapp, 2011-2012
-# Revised by Roger Leigh, 2016
+# Copyright (C) 2007-2015 Glenn Randers-Pehrson

 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h

-cmake_minimum_required(VERSION 2.8.3)
-cmake_policy(VERSION 2.8.3)
-
-# Set MacOSX @rpath usage globally.
-if (POLICY CMP0020)
-  cmake_policy(SET CMP0020 NEW)
-endif(POLICY CMP0020)
-if (POLICY CMP0042)
-  cmake_policy(SET CMP0042 NEW)
-endif(POLICY CMP0042)
-# Use new variable expansion policy.
-if (POLICY CMP0053)
-  cmake_policy(SET CMP0053 NEW)
-endif(POLICY CMP0053)
-if (POLICY CMP0054)
-  cmake_policy(SET CMP0054 NEW)
-endif(POLICY CMP0054)
+cmake_minimum_required(VERSION 2.4.4)
+set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)

 set(CMAKE_CONFIGURATION_TYPES "Release;Debug;MinSizeRel;RelWithDebInfo")

@@ -35,7 +16,7 @@ enable_testing()

 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 25)
+set(PNGLIB_RELEASE 21)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})

@@ -66,284 +47,32 @@ option(PNG_FRAMEWORK "Build OS X framework" OFF)
 option(PNG_DEBUG     "Build with debug output" OFF)
 option(PNGARG        "Disable ANSI-C prototypes" OFF)

-set(PNG_PREFIX "" CACHE STRING "Prefix to add to the API function names")
-set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
-
 # SET LIBNAME
 set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})

 # to distinguish between debug and release lib
 set(CMAKE_DEBUG_POSTFIX "d")

-include(CheckCSourceCompiles)
-option(ld-version-script "Enable linker version script" ON)
-if(ld-version-script AND NOT APPLE)
-  # Check if LD supports linker scripts.
-  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/conftest.map" "VERS_1 {
-        global: sym;
-        local: *;
-};
-
-VERS_2 {
-        global: sym2;
-                main;
-} VERS_1;
-")
-  set(CMAKE_REQUIRED_FLAGS_SAVE ${CMAKE_REQUIRED_FLAGS})
-  set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS} "-Wl,--version-script='${CMAKE_CURRENT_BINARY_DIR}/conftest.map'")
-  check_c_source_compiles("void sym(void) {}
-void sym2(void) {}
-int main(void) {return 0;}
-" HAVE_LD_VERSION_SCRIPT)
-  if(NOT HAVE_LD_VERSION_SCRIPT)
-    set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_SAVE} "-Wl,-M -Wl,${CMAKE_CURRENT_BINARY_DIR}/conftest.map")
-  check_c_source_compiles("void sym(void) {}
-void sym2(void) {}
-int main(void) {return 0;}
-" HAVE_SOLARIS_LD_VERSION_SCRIPT)
-  endif()
-  set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_SAVE})
-  file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/conftest.map")
-endif()
-
-# Find symbol prefix.  Likely obsolete and unnecessary with recent
-# toolchains (it's not done in many other projects).
-function(symbol_prefix)
-  set(SYMBOL_PREFIX)
-
-  execute_process(COMMAND "${CMAKE_C_COMPILER}" "-E" "-"
-                  INPUT_FILE /dev/null
-                  OUTPUT_VARIABLE OUT
-                  RESULT_VARIABLE STATUS)
-
-  if(CPP_FAIL)
-    message(WARNING "Failed to run the C preprocessor")
-  endif()
-
-  string(REPLACE "\n" ";" OUT "${OUT}")
-  foreach(line ${OUT})
-    string(REGEX MATCH "^PREFIX=" found_match "${line}")
-    if(found_match)
-      STRING(REGEX REPLACE "^PREFIX=(.*\)" "\\1" prefix "${line}")
-      string(REGEX MATCH "__USER_LABEL_PREFIX__" found_match "${prefix}")
-      if(found_match)
-        STRING(REGEX REPLACE "(.*)__USER_LABEL_PREFIX__(.*)" "\\1\\2" prefix "${prefix}")
-      endif()
-      set(SYMBOL_PREFIX "${prefix}")
-    endif()
-  endforeach()
-
-    message(STATUS "Symbol prefix: ${SYMBOL_PREFIX}")
-    set(SYMBOL_PREFIX "${SYMBOL_PREFIX}" PARENT_SCOPE)
-endfunction()
-
-if(UNIX)
-  symbol_prefix()
-endif()
-
-find_program(AWK NAMES gawk awk)
-
+# Use the prebuilt pnglibconf.h file from the scripts folder
+# TODO: fix this by building with awk; without this no cmake build can be
+# configured directly (to do so indirectly use your local awk to build a
+# pnglibconf.h in the build directory.)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
+               ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
 include_directories(${CMAKE_CURRENT_BINARY_DIR})

-if(NOT AWK)
-  # No awk available to generate sources; use pre-built pnglibconf.h
-  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
-                 ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
-  add_custom_target(genfiles) # Dummy
-else()
-  include(CMakeParseArguments)
-  # Generate .chk from .out with awk
-  # generate_chk(INPUT inputfile OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_chk)
-    set(options)
-    set(oneValueArgs INPUT OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GC "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GC_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
-    endif()
-    if (NOT _GC_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${_GC_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DINPUT=${_GC_INPUT}"
-                               "-DOUTPUT=${_GC_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/genchk.cmake"
-                       DEPENDS "${_GC_INPUT}" ${_GC_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Generate .out from .c with awk
-  # generate_out(INPUT inputfile OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_out)
-    set(options)
-    set(oneValueArgs INPUT OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GO_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
-    endif()
-    if (NOT _GO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${_GO_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DINPUT=${_GO_INPUT}"
-                               "-DOUTPUT=${_GO_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/genout.cmake"
-                       DEPENDS "${_GO_INPUT}" ${_GO_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Generate specific source file with awk
-  # generate_source(OUTPUT outputfile [DEPENDS dep1 [dep2...]])
-  function(generate_source)
-    set(options)
-    set(oneValueArgs OUTPUT)
-    set(multiValueArgs DEPENDS)
-    cmake_parse_arguments(_GSO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GSO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_source requires output.")
-    endif()
-
-    add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${_GSO_OUTPUT}"
-                       COMMAND "${CMAKE_COMMAND}"
-                               "-DOUTPUT=${_GSO_OUTPUT}"
-                               -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake"
-                       DEPENDS ${_GSO_DEPENDS}
-                       WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-  endfunction()
-
-  # Copy file
-  function(generate_copy source destination)
-    add_custom_command(OUTPUT "${destination}"
-                       COMMAND "${CMAKE_COMMAND}" -E remove "${destination}"
-                       COMMAND "${CMAKE_COMMAND}" -E copy "${source}"
-                                                          "${destination}"
-                       DEPENDS "${source}")
-  endfunction()
-
-  # Generate scripts/pnglibconf.h
-  generate_source(OUTPUT "scripts/pnglibconf.c"
-                  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.dfa"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/scripts/options.awk"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h")
-
-  # Generate pnglibconf.c
-  generate_source(OUTPUT "pnglibconf.c"
-                  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.dfa"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/scripts/options.awk"
-                          "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h")
-
-  if(PNG_PREFIX)
-    set(PNGLIBCONF_H_EXTRA_DEPENDS
-        "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-        "${CMAKE_CURRENT_SOURCE_DIR}/scripts/macro.lst")
-    set(PNGPREFIX_H_EXTRA_DEPENDS
-        "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out")
-  endif()
-
-  generate_out(INPUT "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out")
-
-  # Generate pnglibconf.h
-  generate_source(OUTPUT "pnglibconf.h"
-                  DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out"
-                          ${PNGLIBCONF_H_EXTRA_DEPENDS})
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/intprefix.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out"
-               DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/prefix.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out")
-
-  # Generate pngprefix.h
-  generate_source(OUTPUT "pngprefix.h"
-                  DEPENDS ${PNGPREFIX_H_EXTRA_DEPENDS})
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/sym.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-               DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/symbols.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt")
-
-  generate_out(INPUT "${CMAKE_CURRENT_SOURCE_DIR}/scripts/vers.c"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/png.h"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/pngconf.h"
-                       "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h")
-
-  generate_chk(INPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-               OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
-               DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/scripts/checksym.awk"
-                       "${CMAKE_CURRENT_SOURCE_DIR}/scripts/symbols.def")
-
-  add_custom_target(symbol-check DEPENDS
-                    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk")
-
-  generate_copy("${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-                "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym")
-  generate_copy("${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out"
-                "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers")
-
-  add_custom_target(genvers DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers")
-  add_custom_target(gensym DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym")
-
-  add_custom_target("genprebuilt"
-                    COMMAND "${CMAKE_COMMAND}"
-                            "-DOUTPUT=scripts/pnglibconf.h.prebuilt"
-                            -P "${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake"
-                    WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
-
-  # A single target handles generation of all generated files.  If
-  # they are dependend upon separately by multiple targets, this
-  # confuses parallel make (it would require a separate top-level
-  # target for each file to track the dependencies properly).
-  add_custom_target(genfiles DEPENDS
-    "${CMAKE_CURRENT_BINARY_DIR}/libpng.sym"
-    "${CMAKE_CURRENT_BINARY_DIR}/libpng.vers"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.c"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h"
-    "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/intprefix.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/pnglibconf.c"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/prefix.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/sym.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out")
-endif(NOT AWK)
-
 # OUR SOURCES
 set(libpng_public_hdrs
  png.h
  pngconf.h
-  "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h"
+  ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h
 )
-set(libpng_private_hdrs
-  pngpriv.h
-  pngdebug.h
-  pnginfo.h
-  pngstruct.h
-)
-if(AWK)
-  list(APPEND libpng_private_hdrs "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h")
-endif()
 set(libpng_sources
  ${libpng_public_hdrs}
-  ${libpng_private_hdrs}
+  pngdebug.h
+  pnginfo.h
+  pngpriv.h
+  pngstruct.h
  png.c
  pngerror.c
  pngget.c
@@ -369,18 +98,7 @@ set(pngvalid_sources
 set(pngstest_sources
  contrib/libtests/pngstest.c
 )
-set(pngunknown_sources
-  contrib/libtests/pngunknown.c
-)
-set(pngimage_sources
-  contrib/libtests/pngimage.c
-)
-set(pngfix_sources
-  contrib/tools/pngfix.c
-)
-set(png_fix_itxt_sources
-  contrib/tools/png-fix-itxt.c
-)
+# SOME NEEDED DEFINITIONS

 if(MSVC)
  add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
@@ -396,59 +114,33 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${ZLIB_INCLUDE_DIR})
 unset(PNG_LIB_TARGETS)

 if(PNG_SHARED)
-  add_library(png SHARED ${libpng_sources})
-  set(PNG_LIB_TARGETS png)
-  set_target_properties(png PROPERTIES OUTPUT_NAME ${PNG_LIB_NAME})
-  add_dependencies(png genfiles)
+  add_library(${PNG_LIB_NAME} SHARED ${libpng_sources})
+  set(PNG_LIB_TARGETS ${PNG_LIB_NAME})
  if(MSVC)
    # msvc does not append 'lib' - do it here to have consistent name
-    set_target_properties(png PROPERTIES PREFIX "lib")
-    set_target_properties(png PROPERTIES IMPORT_PREFIX "lib")
-  endif()
-  target_link_libraries(png ${ZLIB_LIBRARY} ${M_LIBRARY})
-
-  if(UNIX AND AWK)
-    if(HAVE_LD_VERSION_SCRIPT)
-      set_target_properties(png PROPERTIES LINK_FLAGS
-        "-Wl,--version-script='${CMAKE_CURRENT_BINARY_DIR}/libpng.vers'")
-    elseif(HAVE_SOLARIS_LD_VERSION_SCRIPT)
-      set_target_properties(png PROPERTIES LINK_FLAGS
-        "-Wl,-M -Wl,'${CMAKE_CURRENT_BINARY_DIR}/libpng.vers'")
-    endif()
+    set_target_properties(${PNG_LIB_NAME} PROPERTIES PREFIX "lib")
+    set_target_properties(${PNG_LIB_NAME} PROPERTIES IMPORT_PREFIX "lib")
  endif()
+  target_link_libraries(${PNG_LIB_NAME} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(PNG_STATIC)
  # does not work without changing name
-  set(PNG_LIB_NAME_STATIC png_static)
-  add_library(png_static STATIC ${libpng_sources})
-  add_dependencies(png_static genfiles)
-  # MSVC doesn't use a different file extension for shared vs. static
-  # libs.  We are able to change OUTPUT_NAME to remove the _static
-  # for all other platforms.
-  if(NOT MSVC)
-    set_target_properties(png_static PROPERTIES
-      OUTPUT_NAME "${PNG_LIB_NAME}"
-      CLEAN_DIRECT_OUTPUT 1)
-  else()
-    set_target_properties(png_static PROPERTIES
-      OUTPUT_NAME "${PNG_LIB_NAME}_static"
-      CLEAN_DIRECT_OUTPUT 1)
-  endif()
-  list(APPEND PNG_LIB_TARGETS png_static)
+  set(PNG_LIB_NAME_STATIC ${PNG_LIB_NAME}_static)
+  add_library(${PNG_LIB_NAME_STATIC} STATIC ${libpng_sources})
+  list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_STATIC})
  if(MSVC)
    # msvc does not append 'lib' - do it here to have consistent name
-    set_target_properties(png_static PROPERTIES PREFIX "lib")
+    set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES PREFIX "lib")
  endif()
-  target_link_libraries(png_static ${ZLIB_LIBRARY} ${M_LIBRARY})
+  target_link_libraries(${PNG_LIB_NAME_STATIC} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(PNG_FRAMEWORK)
-  set(PNG_LIB_NAME_FRAMEWORK png_framework)
-  add_library(png_framework SHARED ${libpng_sources})
-  add_dependencies(png_framework genfiles)
-  list(APPEND PNG_LIB_TARGETS png_framework)
-  set_target_properties(png_framework PROPERTIES
+  set(PNG_LIB_NAME_FRAMEWORK ${PNG_LIB_NAME}_framework)
+  add_library(${PNG_LIB_NAME_FRAMEWORK} SHARED ${libpng_sources})
+  list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_FRAMEWORK})
+  set_target_properties(${PNG_LIB_NAME_FRAMEWORK} PROPERTIES
    FRAMEWORK TRUE
    FRAMEWORK_VERSION ${PNGLIB_VERSION}
    MACOSX_FRAMEWORK_SHORT_VERSION_STRING ${PNGLIB_MAJOR}.${PNGLIB_MINOR}
@@ -457,7 +149,7 @@ if(PNG_FRAMEWORK)
    XCODE_ATTRIBUTE_INSTALL_PATH "@rpath"
    PUBLIC_HEADER "${libpng_public_hdrs}"
    OUTPUT_NAME png)
-  target_link_libraries(png_framework ${ZLIB_LIBRARY} ${M_LIBRARY})
+  target_link_libraries(${PNG_LIB_NAME_FRAMEWORK} ${ZLIB_LIBRARY} ${M_LIBRARY})
 endif()

 if(NOT PNG_LIB_TARGETS)
@@ -468,170 +160,52 @@ if(NOT PNG_LIB_TARGETS)
 endif()

 if(PNG_SHARED AND WIN32)
-  set_target_properties(png PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
+  set_target_properties(${PNG_LIB_NAME} PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
 endif()

-function(png_add_test)
-  set(options)
-  set(oneValueArgs NAME COMMAND)
-  set(multiValueArgs OPTIONS FILES)
-  cmake_parse_arguments(_PAT "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-
-  if (NOT _PAT_NAME)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires name.")
-  endif()
-  if (NOT _PAT_COMMAND)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires command.")
-  endif()
-
-  set(TEST_OPTIONS "${_PAT_OPTIONS}")
-  set(TEST_FILES "${_PAT_FILES}")
-
-  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/scripts/test.cmake.in"
-                 "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake" @ONLY)
-  if(CMAKE_MAJOR_VERSION GREATER 2) # have generator expressions
-    add_test(NAME "${_PAT_NAME}"
-             COMMAND "${CMAKE_COMMAND}"
-             "-DLIBPNG=$<TARGET_FILE:png>"
-             "-DTEST_COMMAND=$<TARGET_FILE:${_PAT_COMMAND}>"
-             -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
-  else() # old 2.x add_test; limited and won't work well on Windows
-    # Note LIBPNG is a dummy value as there are no generator expressions
-    add_test("${_PAT_NAME}" "${CMAKE_COMMAND}"
-             "-DLIBPNG=${CMAKE_CURRENT_BINARY_DIR}/libpng.so"
-             "-DTEST_COMMAND=./${_PAT_COMMAND}"
-             -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
-  endif()
-endfunction()
-
 if(PNG_TESTS AND PNG_SHARED)
-  # Find test PNG files by globbing, but sort lists to ensure
-  # consistency between different filesystems.
-  file(GLOB PNGSUITE_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/*.png")
-  list(SORT PNGSUITE_PNGS)
-  file(GLOB TEST_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/*.png")
-  list(SORT TEST_PNGS)
-
-  set(PNGTEST_PNG "${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png")
-
+  # does not work with msvc due to png_lib_ver issue
  add_executable(pngtest ${pngtest_sources})
-  target_link_libraries(pngtest png)
-
-  png_add_test(NAME pngtest COMMAND pngtest FILES "${PNGTEST_PNG}")
-
+  target_link_libraries(pngtest ${PNG_LIB_NAME})
+  add_test(pngtest ./pngtest ${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png)
+  #
  add_executable(pngvalid ${pngvalid_sources})
-  target_link_libraries(pngvalid png)
-
-  png_add_test(NAME pngvalid-gamma-16-to-8
-               COMMAND pngvalid OPTIONS --gamma-16-to-8)
-  png_add_test(NAME pngvalid-gamma-alpha-mode
-               COMMAND pngvalid OPTIONS --gamma-alpha-mode)
-  png_add_test(NAME pngvalid-gamma-background
-               COMMAND pngvalid OPTIONS --gamma-background)
-  png_add_test(NAME pngvalid-gamma-expand16-alpha-mode
-               COMMAND pngvalid OPTIONS --gamma-alpha-mode --expand16)
-  png_add_test(NAME pngvalid-gamma-expand16-background
-               COMMAND pngvalid OPTIONS --gamma-background --expand16)
-  png_add_test(NAME pngvalid-gamma-expand16-transform
-               COMMAND pngvalid OPTIONS --gamma-transform --expand16)
-  png_add_test(NAME pngvalid-gamma-sbit
-               COMMAND pngvalid OPTIONS --gamma-sbit)
-  png_add_test(NAME pngvalid-gamma-threshold
-               COMMAND pngvalid OPTIONS --gamma-threshold)
-  png_add_test(NAME pngvalid-gamma-transform
-               COMMAND pngvalid OPTIONS --gamma-transform)
-  png_add_test(NAME pngvalid-progressive-interlace-standard
-               COMMAND pngvalid OPTIONS --standard --progressive-read --interlace)
-  png_add_test(NAME pngvalid-progressive-size
-               COMMAND pngvalid OPTIONS --size --progressive-read)
-  png_add_test(NAME pngvalid-progressive-standard
-               COMMAND pngvalid OPTIONS --standard --progressive-read)
-  png_add_test(NAME pngvalid-standard
-               COMMAND pngvalid OPTIONS --standard)
-  png_add_test(NAME pngvalid-transform
-               COMMAND pngvalid OPTIONS --transform)
-
+  target_link_libraries(pngvalid ${PNG_LIB_NAME})
+  add_test(pngvalid ./pngvalid)
  add_executable(pngstest ${pngstest_sources})
-  target_link_libraries(pngstest png)
-
-  foreach(gamma_type 1.8 linear none sRGB)
-    foreach(alpha_type none alpha)
-      set(PNGSTEST_FILES)
-      foreach(test_png ${TEST_PNGS})
-        string(REGEX MATCH ".*-linear[-.].*" TEST_PNG_LINEAR "${test_png}")
-        string(REGEX MATCH ".*-sRGB[-.].*" TEST_PNG_SRGB "${test_png}")
-        string(REGEX MATCH ".*-1.8[-.].*" TEST_PNG_G18 "${test_png}")
-        string(REGEX MATCH ".*-alpha-.*" TEST_PNG_ALPHA "${test_png}")
-
-        set(TEST_PNG_VALID TRUE)
-
-        if(TEST_PNG_ALPHA)
-          if (NOT "${alpha_type}" STREQUAL "alpha")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        else()
-          if ("${alpha_type}" STREQUAL "alpha")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        endif()
-
-        if(TEST_PNG_LINEAR)
-          if(NOT "${gamma_type}" STREQUAL "linear")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        elseif(TEST_PNG_SRGB)
-          if(NOT "${gamma_type}" STREQUAL "sRGB")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        elseif(TEST_PNG_G18)
-          if(NOT "${gamma_type}" STREQUAL "1.8")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        else()
-          if(NOT "${gamma_type}" STREQUAL "none")
-            set(TEST_PNG_VALID FALSE)
-          endif()
-        endif()
-
-        if(TEST_PNG_VALID)
-          list(APPEND PNGSTEST_FILES "${test_png}")
-        endif()
-      endforeach()
-      # Should already be sorted, but sort anyway to be certain.
-      list(SORT PNGSTEST_FILES)
-      png_add_test(NAME pngstest-${gamma_type}-${alpha_type}
-                   COMMAND pngstest
-                   OPTIONS --tmpfile "${gamma_type}-${alpha_type}-" --log
-                   FILES ${PNGSTEST_FILES})
-    endforeach()
-  endforeach()
-
-  add_executable(pngunknown ${pngunknown_sources})
-  target_link_libraries(pngunknown png)
-
-  png_add_test(NAME pngunknown-discard COMMAND pngunknown OPTIONS --strict default=discard FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-IDAT COMMAND pngunknown OPTIONS --strict default=discard IDAT=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-if-safe COMMAND pngunknown OPTIONS --strict default=if-safe FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-sAPI COMMAND pngunknown OPTIONS --strict bKGD=save cHRM=save gAMA=save all=discard iCCP=save sBIT=save sRGB=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-save COMMAND pngunknown OPTIONS --strict default=save FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-sTER COMMAND pngunknown OPTIONS --strict sTER=if-safe FILES "${PNGTEST_PNG}")
-  png_add_test(NAME pngunknown-vpAg COMMAND pngunknown OPTIONS --strict vpAg=if-safe FILES "${PNGTEST_PNG}")
-
-  add_executable(pngimage ${pngimage_sources})
-  target_link_libraries(pngimage png)
-
-  png_add_test(NAME pngimage-quick COMMAND pngimage OPTIONS --list-combos --log FILES ${PNGSUITE_PNGS})
-  png_add_test(NAME pngimage-full COMMAND pngimage OPTIONS --exhaustive --list-combos --log FILES ${PNGSUITE_PNGS})
-endif()
-
-if(PNG_SHARED)
-  add_executable(pngfix ${pngfix_sources})
-  target_link_libraries(pngfix png)
-  set(PNG_BIN_TARGETS pngfix)
-
-  add_executable(png-fix-itxt ${png_fix_itxt_sources})
-  target_link_libraries(png-fix-itxt ${ZLIB_LIBRARY} ${M_LIBRARY})
-  list(APPEND PNG_BIN_TARGETS png-fix-itxt)
+  target_link_libraries(pngstest ${PNG_LIB_NAME})
+  add_test(pngstest ./pngstest
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g01.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g02.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g04.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn2c16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbrn2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn0g16.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbyn3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n0g08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n2c08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n3p08.png
+    ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp1n3p08.png
+  )
 endif()

 # Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
@@ -660,15 +234,6 @@ macro(CREATE_SYMLINK SRC_FILE DEST_FILE)
  endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
 endmacro()

-# Create source generation scripts.
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genchk.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/genchk.cmake @ONLY)
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genout.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/genout.cmake @ONLY)
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/gensrc.cmake.in
-               ${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake @ONLY)
-
-
 # libpng is a library so default to 'lib'
 if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
  set(CMAKE_INSTALL_LIBDIR lib)
@@ -695,12 +260,22 @@ endif(NOT WIN32 OR CYGWIN OR MINGW)

 # SET UP LINKS
 if(PNG_SHARED)
-  set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.25
+  set_target_properties(${PNG_LIB_NAME} PROPERTIES
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.21
    VERSION 16.${PNGLIB_RELEASE}.0
    SOVERSION 16
    CLEAN_DIRECT_OUTPUT 1)
 endif()
+if(PNG_STATIC)
+  # MSVC doesn't use a different file extension for shared vs. static
+  # libs.  We are able to change OUTPUT_NAME to remove the _static
+  # for all other platforms.
+  if(NOT MSVC)
+    set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES
+      OUTPUT_NAME ${PNG_LIB_NAME}
+      CLEAN_DIRECT_OUTPUT 1)
+  endif()
+endif()

 # If CMake > 2.4.x, we set a variable used below to export
 # targets to an export file.
@@ -723,14 +298,14 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
  if(PNG_SHARED)
    # Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
    if(CYGWIN OR MINGW)
-       get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+       get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
       CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_IMPORT_LIBRARY_SUFFIX})
       install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
    endif(CYGWIN OR MINGW)

    if(NOT WIN32)
-      get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+      get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_SHARED_LIBRARY_SUFFIX})
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
@@ -739,7 +314,7 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )

  if(PNG_STATIC)
    if(NOT WIN32 OR CYGWIN OR MINGW)
-      get_target_property(BUILD_TARGET_LOCATION png_static LOCATION_${CMAKE_BUILD_TYPE})
+      get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME_STATIC} LOCATION_${CMAKE_BUILD_TYPE})
      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_STATIC_LIBRARY_SUFFIX})
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
         DESTINATION ${CMAKE_INSTALL_LIBDIR})
@@ -759,11 +334,6 @@ if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL )
  endif(NOT WIN32 OR CYGWIN OR MINGW)
 endif()

-if(NOT SKIP_INSTALL_PROGRAMS AND NOT SKIP_INSTALL_ALL )
-  install(TARGETS ${PNG_BIN_TARGETS}
-      RUNTIME DESTINATION bin)
-endif()
-
 if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
  # Install man pages
  if(NOT PNG_MAN_DIR)
--- a/121
+++ b/121
@@ -1,25 +1,24 @@

-    Installing libpng
+Installing libpng

 Contents

-       I. Simple installation
-      II. Rebuilding the configure scripts
-     III. Using scripts/makefile*
-      IV. Using cmake
-       V. Directory structure
-      VI. Building with project files
-     VII. Building with makefiles
-    VIII. Configuring libpng for 16-bit platforms
-      IX. Configuring for DOS
-       X. Configuring for Medium Model
-      XI. Prepending a prefix to exported symbols
-     XII. Configuring for compiler xxx:
-    XIII. Removing unwanted object code
-     XIV. Changes to the build and configuration of libpng in libpng-1.5.x
-      XV. Setjmp/longjmp issues
-     XVI. Common linking failures
-    XVII. Other sources of information about libpng
+   I. Simple installation
+  II. Rebuilding the configure scripts
+ III. Using scripts/makefile*
+  IV. Using cmake
+   V. Directory structure
+  VI. Building with project files
+ VII. Building with makefiles
+VIII. Configuring libpng for 16-bit platforms
+  IX. Configuring for DOS
+   X. Configuring for Medium Model
+  XI. Prepending a prefix to exported symbols
+ XII. Configuring for compiler xxx:
+XIII. Removing unwanted object code
+ XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+  XV. Setjmp/longjmp issues
+ XVI. Other sources of information about libpng

 I. Simple installation

@@ -48,9 +47,7 @@ If configure does not work on your system, or if you have a need to
 change configure.ac or Makefile.am, and you have a reasonably
 up-to-date set of tools, running ./autogen.sh in a git clone before
 running ./configure may fix the problem.  To be really sure that you
-aren't using any of the included pre-built scripts, especially if you
-are building from a tar distribution instead of a git distribution,
-do this:
+aren't using any of the included pre-built scripts, you can do this:

    ./configure --enable-maintainer-mode
    make maintainer-clean
@@ -79,7 +76,7 @@ Or you can use one of the "projects" in the "projects" directory.
 Before installing libpng, you must first install zlib, if it
 is not already on your system.  zlib can usually be found
 wherever you got libpng; otherwise go to http://zlib.net.  You can place
-zlib in the same directory as libpng or in another directory.
+zlib in in the same directory as libpng or in another directory.

 If your system already has a preinstalled zlib you will still need
 to have access to the zlib.h and zconf.h include files that
@@ -90,24 +87,22 @@ standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
 and LD_LIBRARY_PATH in your environment before running "make test"
 or "make distcheck":

-    ZLIBLIB=/path/to/lib export ZLIBLIB
-    ZLIBINC=/path/to/include export ZLIBINC
-    CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
-    LDFLAGS="-L$ZLIBLIB" export LDFLAGS
-    LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
+ZLIBLIB=/path/to/lib export ZLIBLIB
+ZLIBINC=/path/to/include export ZLIBINC
+CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
+LDFLAGS="-L$ZLIBLIB" export LDFLAGS
+LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH

 If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
-in your environment and type
-
-    make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test
+in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".

 IV. Using cmake

 If you want to use "cmake" (see www.cmake.org), type

-    cmake . -DCMAKE_INSTALL_PREFIX=/path
-    make
-    make install
+   cmake . -DCMAKE_INSTALL_PREFIX=/path
+   make
+   make install

 As when using the simple configure method described above, "/path" points to
 the installation directory where you want to put the libpng "lib", "include",
@@ -121,8 +116,8 @@ or "zlib128") so that you have directories called "zlib" and "libpng".

 Your directory structure should look like this:

-    .. (the parent directory)
-      libpng (this directory)
+   ..       (the parent directory)
+      libpng  (this directory)
          INSTALL (this file)
          README
          *.h, *.c  => libpng source files
@@ -165,15 +160,10 @@ VII. Building with makefiles
 Copy the file (or files) that you need from the
 scripts directory into this directory, for example

-MSDOS example:
-
-    copy scripts\makefile.msc makefile
-    copy scripts\pnglibconf.h.prebuilt pnglibconf.h
-
-UNIX example:
-
-    cp scripts/makefile.std makefile
-    cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+   MSDOS example: copy scripts\makefile.msc makefile
+                  copy scripts\pnglibconf.h.prebuilt pnglibconf.h
+   UNIX example:  cp scripts/makefile.std makefile
+                  cp scripts/pnglibconf.h.prebuilt pnglibconf.h

 Read the makefile to see if you need to change any source or
 target directories to match your preferences.
@@ -249,7 +239,7 @@ libpng are compiled.  All the defines end in _SUPPORTED.  If you are
 never going to use a capability, you can change the #define to #undef
 before recompiling libpng and save yourself code and data space, or
 you can turn off individual capabilities with defines that begin with
-"PNG_NO_".
+PNG_NO_.

 In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.

@@ -317,7 +307,7 @@ only png_longjmp_ptr, which must match the C longjmp function.)  The new
 approach is documented in pngconf.h

 Despite these changes, libpng 1.5.0 only supports the native C function
-calling standard on those platforms tested so far ("__cdecl" on Microsoft
+calling standard on those platforms tested so far (__cdecl on Microsoft
 Windows).  This is because the support requirements for alternative
 calling conventions seem to no longer exist.  Developers who find it
 necessary to set PNG_API_RULE to 1 should advise the mailing list
@@ -381,7 +371,7 @@ your application is going to be using multiple threads, you should
 configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
 -DPNG_NO_SETJMP on your compile line, or with

-    #undef PNG_SETJMP_SUPPORTED
+  #undef PNG_SETJMP_SUPPORTED

 in your pnglibconf.h or pngusr.h.

@@ -390,25 +380,28 @@ This requires setjmp/longjmp, so you must either build the library
 with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
 and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.

-XVI. Common linking failures
-
-If your application fails to find libpng or zlib entries while linking:
-
-  Be sure "-lz" appears after "-lpng" on your linking command.
-
-  Be sure you have built libpng, zlib, and your application for the
-  same platform (e.g., 32-bit or 64-bit).
-
-  If you are using the vstudio project, observe the WARNING in
-  project/vstudio/README.txt.
-
-XVII. Other sources of information about libpng:
+XVI. Other sources of information about libpng:

 Further information can be found in the README and libpng-manual.txt
 files, in the individual makefiles, in png.h, and the manual pages
 libpng.3 and png.5.

-Copyright (c) 1998-2002,2006-2016 Glenn Randers-Pehrson
-This document is released under the libpng license.
-For conditions of distribution and use, see the disclaimer
-and license in png.h.
+Using the ./configure script -- 16 December 2002.
+=================================================
+
+The ./configure script should work compatibly with what scripts/makefile.*
+did, however there are some options you might need to add to configure
+explicitly, which previously was done semi-automatically (if you didn't edit
+scripts/makefile.* yourself, that is)
+
+CFLAGS="-Wall -O -funroll-loops \
+-malign-loops=2 -malign-functions=2" ./configure --prefix=/usr/include \
+--with-pkgconfigdir=/usr/lib/pkgconfig --includedir=/usr/include
+
+You can alternatively specify --includedir=/usr/include, /usr/local/include,
+/usr/include/libpng16, or whatever.
+
+If you find that the configure script is out-of-date or is not supporting
+your platform properly, try running autogen.sh to regenerate "configure",
+"Makefile.in", and the other configuration files. Then try configure again.
+
--- a/32
+++ b/32
@@ -10,7 +10,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -32,10 +32,6 @@ and with the following additions to the disclaimer:
   risk of satisfactory quality, performance, accuracy, and effort is with
   the user.

-Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
-are released under other open source licenses.
-
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
@@ -59,9 +55,6 @@ Contributing Authors:
   Greg Roelofs
   Tom Tanner

-Some files in the "scripts" directory have other copyright owners
-but are released under this license.
-
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

@@ -102,29 +95,18 @@ appreciated.

 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

-TRADEMARK:
+A "png_get_copyright" function is available, for convenient use in "about"
+boxes and the like:

-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction.  However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
+   printf("%s", png_get_copyright(NULL));

-OSI CERTIFICATION:
+Also, the PNG logo (in PNG format, of course) is supplied in the
+files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).

 Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 a certification mark of the Open Source Initiative. OSI has not addressed
 the additional disclaimers inserted at version 1.0.7.

-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-September 1, 2016
+January 15, 2016
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,21 +1,13 @@
-# Makefile.am, the source file for Makefile.in (and hence Makefile), is
+# Makefile.am:
+#   Source file for Makefile.in (and hence Makefile)
 #
-# Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
-#
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h

 PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@

 ACLOCAL_AMFLAGS = -I scripts

 # test programs - run on make check, make distcheck
-check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage pngcp
-if HAVE_CLOCK_GETTIME
-check_PROGRAMS += timepng
-endif
+check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage

 # Utilities - installed
 bin_PROGRAMS= pngfix png-fix-itxt
@@ -45,17 +37,11 @@ pngunknown_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 pngimage_SOURCES = contrib/libtests/pngimage.c
 pngimage_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la

-timepng_SOURCES = contrib/libtests/timepng.c
-timepng_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
-
 pngfix_SOURCES = contrib/tools/pngfix.c
 pngfix_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la

 png_fix_itxt_SOURCES = contrib/tools/png-fix-itxt.c

-pngcp_SOURCES = contrib/tools/pngcp.c
-pngcp_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
-
 # Generally these are single line shell scripts to run a test with a particular
 # set of parameters:
 TESTS =\
@@ -97,11 +83,6 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
 	arm/filter_neon.S arm/filter_neon_intrinsics.c
 endif

-if PNG_MIPS_MSA
-libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
-	mips/filter_msa_intrinsics.c
-endif
-
 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h

 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
@@ -238,7 +219,6 @@ contrib/libtests/timepng.o: pnglibconf.h

 contrib/tools/makesRGB.o: pnglibconf.h
 contrib/tools/pngfix.o: pnglibconf.h
-contrib/tools/pngcp.o: pnglibconf.h

 # We must use -DPNG_NO_USE_READ_MACROS here even when the library may actually
 # be built with PNG_USE_READ_MACROS; this prevents the read macros from
--- a/5
+++ b/5
@@ -1,4 +1,4 @@
-README for libpng version 1.6.25 - September 1, 2016 (shared library 16.0)
+README for libpng version 1.6.21 - January 15, 2016 (shared library 16.0)
 See the note about version numbers near the top of png.h

 See INSTALL for instructions on how to install libpng.
@@ -180,18 +180,15 @@ Files in this distribution:
      pngwutil.c    =>  Write utility functions
      arm           =>  Contains optimized code for the ARM platform
      contrib       =>  Contributions
-       arm-neon         =>  Optimized code for ARM-NEON platform
       examples         =>  Example programs
       gregbook         =>  source code for PNG reading and writing, from
                            Greg Roelofs' "PNG: The Definitive Guide",
                            O'Reilly, 1999
-       intel            =>  Optimized code for INTEL-SSE2 platform
       libtests         =>  Test programs
       pngminim         =>  Minimal decoder, encoder, and progressive decoder
                            programs demonstrating use of pngusr.dfa
       pngminus         =>  Simple pnm2png and png2pnm programs
       pngsuite         =>  Test images
-       testpngs
       tools            =>  Various tools
       visupng          =>  Contains a MSVC workspace for VisualPng
      projects      =>  Contains project files and workspaces for
--- a/5
+++ b/5
@@ -5,14 +5,13 @@ Final bug fixes.
 Better C++ wrapper/full C++ implementation?
 Fix problem with C++ and EXTERN "C".
 cHRM transformation.
-Remove setjmp/longjmp usage in favor of returning error codes. As a start on
-  this, minimize the use of png_error(), replacing them with
-  png_warning(); return(0; or similar.
+Remove setjmp/longjmp usage in favor of returning error codes.
 Palette creation.
 Add "grayscale->palette" transformation and "palette->grayscale" detection.
 Improved dithering.
 Multi-lingual error and warning message support.
 Complete sRGB transformation (presently it simply uses gamma=0.45455).
+Make profile checking optional via a png_set_something() call.
 Man pages for function calls.
 Better documentation.
 Better filter selection
--- a/arm/arm_init.c
+++ b/arm/arm_init.c
@@ -1,9 +1,9 @@

 /* arm_init.c - NEON optimised filter functions
 *
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Last changed in libpng 1.6.16 [December 22, 2014]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -66,7 +66,6 @@ png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
    * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
    * as documented in png.h
    */
-   png_debug(1, "in png_init_filter_functions_neon");
 #ifdef PNG_ARM_NEON_API_SUPPORTED
   switch ((pp->options >> PNG_ARM_NEON) & 3)
   {
--- a/arm/filter_neon_intrinsics.c
+++ b/arm/filter_neon_intrinsics.c
@@ -1,11 +1,11 @@

 /* filter_neon_intrinsics.c - NEON optimised filter functions
 *
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by James Yu <james.yu at linaro.org>, October 2013.
 * Based on filter_neon.S, written by Mans Rullgard, 2011.
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Last changed in libpng 1.6.16 [December 22, 2014]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -47,8 +47,6 @@ png_read_filter_row_up_neon(png_row_infop row_info, png_bytep row,
   png_bytep rp_stop = row + row_info->rowbytes;
   png_const_bytep pp = prev_row;

-   png_debug(1, "in png_read_filter_row_up_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint8x16_t qrp, qpp;
@@ -74,8 +72,6 @@ png_read_filter_row_sub3_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_sub3_neon");
-
   for (; rp < rp_stop;)
   {
      uint8x8_t vtmp1, vtmp2;
@@ -117,8 +113,6 @@ png_read_filter_row_sub4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_sub4_neon");
-
   for (; rp < rp_stop; rp += 16)
   {
      uint32x2x4_t vtmp = vld4_u32(png_ptr(uint32_t,rp));
@@ -154,8 +148,6 @@ png_read_filter_row_avg3_neon(png_row_infop row_info, png_bytep row,
   vrpt = png_ptr(uint8x8x2_t,&vtmp);
   vrp = *vrpt;

-   png_debug(1, "in png_read_filter_row_avg3_neon");
-
   for (; rp < rp_stop; pp += 12)
   {
      uint8x8_t vtmp1, vtmp2, vtmp3;
@@ -215,8 +207,6 @@ png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_avg4_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint32x2x4_t vtmp;
@@ -290,8 +280,6 @@ png_read_filter_row_paeth3_neon(png_row_infop row_info, png_bytep row,
   vrpt = png_ptr(uint8x8x2_t,&vtmp);
   vrp = *vrpt;

-   png_debug(1, "in png_read_filter_row_paeth3_neon");
-
   for (; rp < rp_stop; pp += 12)
   {
      uint8x8x2_t *vppt;
@@ -351,8 +339,6 @@ png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
   uint8x8x4_t vdest;
   vdest.val[3] = vdup_n_u8(0);

-   png_debug(1, "in png_read_filter_row_paeth4_neon");
-
   for (; rp < rp_stop; rp += 16, pp += 16)
   {
      uint32x2x4_t vtmp;
--- a/configure.ac
+++ b/configure.ac
@@ -1,12 +1,5 @@
 # configure.ac

-# Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
 dnl Process this file with autoconf to produce a configure script.
 dnl
 dnl Minor upgrades (compatible ABI): increment the package version
@@ -25,7 +18,7 @@ AC_PREREQ([2.68])

 dnl Version number stuff here:

-AC_INIT([libpng],[1.6.25],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.21],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])

 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -36,7 +29,7 @@ AC_CONFIG_MACRO_DIR([scripts])
 # 1.13 is required for parallel tests
 AM_INIT_AUTOMAKE([1.13 foreign dist-xz color-tests silent-rules subdir-objects])
 # The following line causes --disable-maintainer-mode to be the default to
-# configure. This is necessary because libpng distributions cannot rely on the
+# configure, this is necessary because libpng distributions cannot rely on the
 # time stamps of the autotools generated files being correct
 AM_MAINTAINER_MODE

@@ -46,10 +39,10 @@ dnl automake, so the following is not necessary (and is not defined anyway):
 dnl AM_PREREQ([1.11.2])
 dnl stop configure from automagically running automake

-PNGLIB_VERSION=1.6.25
+PNGLIB_VERSION=1.6.21
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=25
+PNGLIB_RELEASE=21

 dnl End of version number stuff

@@ -67,7 +60,7 @@ AC_PROG_INSTALL
 AC_PROG_LN_S
 AC_PROG_MAKE_SET

-dnl libtool/libtoolize; version 2.4.2 is the tested version. This or any
+dnl libtool/libtoolize; version 2.4.2 is the tested version, this or any
 dnl compatible later version may be used
 LT_INIT([win32-dll])
 LT_PREREQ([2.4.2])
@@ -114,25 +107,6 @@ AC_ARG_ENABLE(werror,
      CFLAGS="$sav_CFLAGS"
    fi],)

-# For GCC 5 the default mode for C is -std=gnu11 instead of -std=gnu89
-# In pngpriv.h we request just the POSIX 1003.1 and C89 APIs by defining _POSIX_SOURCE to 1
-# This is incompatible with the new default mode, so we test for that and force the 
-# "-std=c89" compiler option:
-AC_MSG_CHECKING([if we need to force back C standard to C89])
-AC_COMPILE_IFELSE(
-   [AC_LANG_PROGRAM([
-      [#define _POSIX_SOURCE 1]
-      [#include <stdio.h>]
-   ])],
-   AC_MSG_RESULT(no),[
-      if test "x$GCC" != "xyes"; then
-         AC_MSG_ERROR(
-            [Forcing back to C89 is required but the flags are only known for GCC])
-      fi
-   AC_MSG_RESULT(yes)
-   CFLAGS="$CFLAGS -std=c89"
-])
-
 # Checks for header files.
 AC_HEADER_STDC

@@ -146,12 +120,6 @@ AC_C_RESTRICT
 AC_FUNC_STRTOD
 AC_CHECK_FUNCS([memset], , AC_MSG_ERROR(memset not found in libc))
 AC_CHECK_FUNCS([pow], , AC_CHECK_LIB(m, pow, , AC_MSG_ERROR(cannot find pow)) )
-
-# Some later POSIX 1003.1 functions are required for test programs, failure here
-# is soft (the corresponding test program is not built).
-AC_CHECK_FUNC([clock_gettime],,[AC_MSG_WARN([not building timepng])])
-AM_CONDITIONAL([HAVE_CLOCK_GETTIME], [test "$ac_cv_func_clock_gettime" = "yes"])
-
 AC_ARG_WITH(zlib-prefix,
   AS_HELP_STRING([[[--with-zlib-prefix]]],
      [prefix that may have been used in installed zlib]),
@@ -346,51 +314,6 @@ AM_CONDITIONAL([PNG_ARM_NEON],
      *)    test "$enable_arm_neon" != '';;
    esac])

-# MIPS
-# ===
-#
-# MIPS MSA (SIMD) support.
-
-AC_ARG_ENABLE([mips-msa],
-   AS_HELP_STRING([[[--enable-mips-msa]]],
-      [Enable MIPS MSA optimizations: =no/off, check, api, yes/on:]
-      [no/off: disable the optimizations; check: use internal checking code]
-      [(deprecated and poorly supported); api: disable by default, enable by]
-      [a call to png_set_option; yes/on: turn on unconditionally.]
-      [If not specified: determined by the compiler.]),
-   [case "$enableval" in
-      no|off)
-         # disable the default enabling on __mips_msa systems:
-         AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
-                   [Disable MIPS MSA optimizations])
-         # Prevent inclusion of the assembler files below:
-         enable_mips_msa=no;;
-      check)
-         AC_DEFINE([PNG_MIPS_MSA_CHECK_SUPPORTED], [],
-                   [Check for MIPS MSA support at run-time]);;
-      api)
-         AC_DEFINE([PNG_MIPS_MSA_API_SUPPORTED], [],
-                   [Turn on MIPS MSA optimizations at run-time]);;
-      yes|on)
-         AC_DEFINE([PNG_MIPS_MSA_OPT], [2],
-                   [Enable MIPS MSA optimizations])
-         AC_MSG_WARN([--enable-mips-msa: please specify 'check' or 'api', if]
-            [you want the optimizations unconditionally pass '-mmsa -mfp64']
-            [to the compiler.]);;
-      *)
-         AC_MSG_ERROR([--enable-mips-msa=${enable_mips_msa}: invalid value])
-   esac])
-
-# Add MIPS specific files to all builds where the host_cpu is mips ('mips*') or
-# where MIPS optimizations were explicitly requested (this allows a fallback if a
-# future host CPU does not match 'mips*')
-
-AM_CONDITIONAL([PNG_MIPS_MSA],
-   [test "$enable_mips_msa" != 'no' &&
-    case "$host_cpu" in
-      mipsel*|mips64el*) :;;
-    esac])
-
 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])

 # Config files, substituting as above
--- a/contrib/conftest/pngcp.dfa
+++ b/contrib/conftest/pngcp.dfa
@@ -1,57 +0,0 @@
-# pngcp.dfa
-#  Build time configuration of libpng
-#
-# Author: John Bowler
-# Copyright: (c) John Bowler, 2016
-# Usage rights:
-#  To the extent possible under law, the author has waived all copyright and
-#  related or neighboring rights to this work.  This work is published from:
-#  United States.
-#
-# Build libpng with support for pngcp.  This means just png_read_png,
-# png_write_png and small number of configuration settings.
-#
-everything = off
-
-# This option is specific to this configuration; it adds a #define to the
-# generated pnglibconf.h which turns on the (not portable) timing option for
-# pngcp.  Note that any option is automatically preceded by PNG_; there is no
-# way round this and this is deliberate.
-option PNGCP_TIMING
-
-# Because of the everything off above the option must also be turned on.  This
-# may not be done in one step because it is safer and avoids mis-spelled options
-# in user .dfa files to error out if an unrecognized option is turned on.
-option PNGCP_TIMING on
-
-# Options to turn on png_read_png and png_write_png:
-option INFO_IMAGE on
-option SEQUENTIAL_READ on
-option EASY_ACCESS on
-option WRITE on
-option WRITE_16BIT on
-option WRITE_FILTER on
-
-# pngcp needs this to preserve unknown chunks, switching all these on means that
-# pngcp can work without explicit known chunk reading suppport
-option UNKNOWN_CHUNKS on
-option SET_UNKNOWN_CHUNKS on
-option HANDLE_AS_UNKNOWN on
-option SAVE_UNKNOWN_CHUNKS on
-option WRITE_UNKNOWN_CHUNKS on
-
-# pngcp needs this to handle palette files with invalid indices:
-option CHECK_FOR_INVALID_INDEX on
-option GET_PALETTE_MAX on
-
-# Pre-libpng 1.7 pngcp has to stash text chunks manually, post 1.7 without this
-# text chunks should be handled as unknown ok.
-option TEXT on
-
-# this is used to turn off limits:
-option USER_LIMITS on
-option SET_USER_LIMITS on
-
-# these are are just required for specific customizations
-option WRITE_CUSTOMIZE_ZTXT_COMPRESSION on
-option WRITE_CUSTOMIZE_COMPRESSION on
--- a/contrib/gregbook/readpng2.c
+++ b/contrib/gregbook/readpng2.c
@@ -54,7 +54,7 @@
  ---------------------------------------------------------------------------

   Changelog:
-     2015-11-12 - Check return value of png_get_bKGD() (Glenn R-P)
+     %RDATE% - Check return value of png_get_bKGD() (Glenn R-P)

  ---------------------------------------------------------------------------*/

--- a/contrib/intel/INSTALL
+++ b/contrib/intel/INSTALL
@@ -1,158 +0,0 @@
-Enabling SSE support
-
-Copyright (c) 2016 Google, Inc.
-Written by Mike Klein, Matt Sarett
-
-This INSTALL file written by Glenn Randers-Pehrson, 2016.
-
-If you have moved intel_init.c and filter_sse2_intrinsics.c to a different
-directory, be sure to update the '#include "../../pngpriv.h"' line in both
-files if necessary to point to the correct relative location of pngpriv.h
-with respect to the new location of those files.
-
-To enable SSE support in libpng, follow the instructions in I, II, or III,
-below:
-
-I. Using patched "configure" scripts:
-
-First, apply intel_sse.patch in your build directory.
-
-   patch -i contrib/intel/intel_sse.patch -p1
-
-Then, if you are not building in a new GIT clone, e.g., in a tar
-distribution, remove any existing pre-built configure scripts:
-
-   ./configure --enable-maintainer-mode
-   make maintainer-clean
-   ./autogen.sh --maintainer --clean
-
-Finally, configure libpng with -DPNG_INTEL_SSE in CPPFLAGS:
-
-   ./autogen.sh --maintainer
-   CPPFLAGS="-DPNG_INTEL_SSE" ./configure [options]
-   make CPPFLAGS="-DPNG_INTEL_SSE" [options]
-   make
-
-II. Using a custom makefile:
-
-If you are using a custom makefile makefile, you will have to update it
-manually to include contrib/intel/*.o in the dependencies, and to define
-PNG_INTEL_SSE.
-
-III. Using manually updated "configure" scripts:
-
-If you prefer, manually edit pngpriv.h, configure.ac, and Makefile.am,
-following the instructions below, then follow the instructions in
-section II of INSTALL in the main libpng directory, then configure libpng
-with -DPNG_INTEL_SSE in CPPFLAGS.
-
-1. Add the following code to configure.ac under HOST SPECIFIC OPTIONS
-directly beneath the section for ARM:
-
-----------------cut----------------
-# INTEL
-# =====
-#
-# INTEL SSE (SIMD) support.
-
-AC_ARG_ENABLE([intel-sse],
-   AS_HELP_STRING([[[--enable-intel-sse]]],
-      [Enable Intel SSE optimizations: =no/off, yes/on:]
-      [no/off: disable the optimizations;]
-      [yes/on: enable the optimizations.]
-      [If not specified: determined by the compiler.]),
-   [case "$enableval" in
-      no|off)
-         # disable the default enabling:
-         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
-                   [Disable Intel SSE optimizations])
-         # Prevent inclusion of the assembler files below:
-         enable_intel_sse=no;;
-      yes|on)
-         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
-                   [Enable Intel SSE optimizations]);;
-      *)
-         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
-   esac])
-
-# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
-# or where Intel optimizations were explicitly requested (this allows a
-# fallback if a future host CPU does not match 'x86*')
-AM_CONDITIONAL([PNG_INTEL_SSE],
-   [test "$enable_intel_sse" != 'no' &&
-    case "$host_cpu" in
-      i?86|x86_64) :;;
-      *)    test "$enable_intel_sse" != '';;
-    esac])
-----------------cut----------------
-
-2. Add the following code to Makefile.am under HOST SPECIFIC OPTIONS
-directly beneath the "if PNG_ARM_NEON ... endif" statement:
-
-----------------cut----------------
-if PNG_INTEL_SSE
-libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
-    contrib/intel/filter_sse2_intrinsics.c
-endif
-----------------cut----------------
-
-3. Add the following lines to pngpriv.h, following the PNG_ARM_NEON_OPT
-code:
-
-----------------cut----------------
-#ifndef PNG_INTEL_SSE_OPT
-#   ifdef PNG_INTEL_SSE
-      /* Only check for SSE if the build configuration has been modified to
-       * enable SSE optimizations.  This means that these optimizations will
-       * be off by default.  See contrib/intel for more details.
-       */
-#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
-       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
-       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
-#         define PNG_INTEL_SSE_OPT 1
-#      endif
-#   endif
-#endif
-
-#if PNG_INTEL_SSE_OPT > 0
-#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
-#      if defined(__SSE4_1__) || defined(__AVX__)
-          /* We are not actually using AVX, but checking for AVX is the best
-             way we can detect SSE4.1 and SSSE3 on MSVC.
-          */
-#         define PNG_INTEL_SSE_IMPLEMENTATION 3
-#      elif defined(__SSSE3__)
-#         define PNG_INTEL_SSE_IMPLEMENTATION 2
-#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
-       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
-#         define PNG_INTEL_SSE_IMPLEMENTATION 1
-#      else
-#         define PNG_INTEL_SSE_IMPLEMENTATION 0
-#      endif
-#   endif
-
-#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
-#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
-#   endif
-#endif
-
-----------------cut----------------
-
-4. Add the following lines to pngpriv.h, following the prototype for
-png_read_filter_row_paeth4_neon:
-
-----------------cut----------------
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-
-----------------cut----------------
--- a/contrib/intel/filter_sse2_intrinsics.c
+++ b/contrib/intel/filter_sse2_intrinsics.c
@@ -1,379 +0,0 @@
-
-/* filter_sse2_intrinsics.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016 Google, Inc.
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/filter_neon_intrinsics.c, which was
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
- *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "../../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-
-#include <immintrin.h>
-
-/* Functions in this file look at most 3 pixels (a,b,c) to predict the 4th (d).
- * They're positioned like this:
- *    prev:  c b
- *    row:   a d
- * The Sub filter predicts d=a, Avg d=(a+b)/2, and Paeth predicts d to be
- * whichever of a, b, or c is closest to p=a+b-c.
- */
-
-static __m128i load4(const void* p) {
-   return _mm_cvtsi32_si128(*(const int*)p);
-}
-
-static void store4(void* p, __m128i v) {
-   *(int*)p = _mm_cvtsi128_si32(v);
-}
-
-static __m128i load3(const void* p) {
-   /* We'll load 2 bytes, then 1 byte,
-    * then mask them together, and finally load into SSE.
-    */
-   const png_uint_16* p01 = p;
-   const png_byte*    p2  = (const png_byte*)(p01+1);
-
-   png_uint_32 v012 = (png_uint_32)(*p01)
-                    | (png_uint_32)(*p2) << 16;
-   return load4(&v012);
-}
-
-static void store3(void* p, __m128i v) {
-   /* We'll pull from SSE as a 32-bit int, then write
-    * its bottom two bytes, then its third byte.
-    */
-   png_uint_32 v012;
-   store4(&v012, v);
-
-   png_uint_16* p01 = p;
-   png_byte*    p2  = (png_byte*)(p01+1);
-   *p01 = v012;
-   *p2  = v012 >> 16;
-}
-
-void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Sub filter predicts each pixel as the previous pixel, a.
-    * There is no pixel to the left of the first pixel.  It's encoded directly.
-    * That works with our main loop if we just say that left pixel was zero.
-    */
-   png_debug(1, "in png_read_filter_row_sub3_sse2");
-   __m128i a, d = _mm_setzero_si128();
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-      a = d; d = load4(row);
-      d = _mm_add_epi8(d, a);
-      store3(row, d);
-
-      row += 3;
-      rb  -= 3;
-   }
-   if (rb > 0) {
-      a = d; d = load3(row);
-      d = _mm_add_epi8(d, a);
-      store3(row, d);
-
-      row += 3;
-      rb  -= 3;
-   }
-}
-
-void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Sub filter predicts each pixel as the previous pixel, a.
-    * There is no pixel to the left of the first pixel.  It's encoded directly.
-    * That works with our main loop if we just say that left pixel was zero.
-    */
-   png_debug(1, "in png_read_filter_row_sub4_sse2");
-   __m128i a, d = _mm_setzero_si128();
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-      a = d; d = load4(row);
-      d = _mm_add_epi8(d, a);
-      store4(row, d);
-
-      row += 4;
-      rb  -= 4;
-   }
-}
-
-void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Avg filter predicts each pixel as the (truncated) average of a and b.
-    * There's no pixel to the left of the first pixel.  Luckily, it's
-    * predicted to be half of the pixel above it.  So again, this works
-    * perfectly with our loop if we make sure a starts at zero.
-    */
-   png_debug(1, "in png_read_filter_row_avg3_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i    b;
-   __m128i a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-      d = _mm_add_epi8(d, avg);
-      store3(row, d);
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-   if (rb > 0) {
-             b = load3(prev);
-      a = d; d = load3(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-
-      d = _mm_add_epi8(d, avg);
-      store3(row, d);
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-}
-
-void png_read_filter_row_avg4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* The Avg filter predicts each pixel as the (truncated) average of a and b.
-    * There's no pixel to the left of the first pixel.  Luckily, it's
-    * predicted to be half of the pixel above it.  So again, this works
-    * perfectly with our loop if we make sure a starts at zero.
-    */
-   png_debug(1, "in png_read_filter_row_avg4_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i    b;
-   __m128i a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      __m128i avg = _mm_avg_epu8(a,b);
-      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
-      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
-                                            _mm_set1_epi8(1)));
-
-      d = _mm_add_epi8(d, avg);
-      store4(row, d);
-
-      prev += 4;
-      row  += 4;
-      rb   -= 4;
-   }
-}
-
-/* Returns |x| for 16-bit lanes. */
-static __m128i abs_i16(__m128i x) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 2
-   return _mm_abs_epi16(x);
-#else
-   /* Read this all as, return x<0 ? -x : x.
-   * To negate two's complement, you flip all the bits then add 1.
-    */
-   __m128i is_negative = _mm_cmplt_epi16(x, _mm_setzero_si128());
-
-   /* Flip negative lanes. */
-   x = _mm_xor_si128(x, is_negative);
-
-   /* +1 to negative lanes, else +0. */
-   x = _mm_sub_epi16(x, is_negative);
-   return x;
-#endif
-}
-
-/* Bytewise c ? t : e. */
-static __m128i if_then_else(__m128i c, __m128i t, __m128i e) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 3
-   return _mm_blendv_epi8(e,t,c);
-#else
-   return _mm_or_si128(_mm_and_si128(c, t), _mm_andnot_si128(c, e));
-#endif
-}
-
-void png_read_filter_row_paeth3_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* Paeth tries to predict pixel d using the pixel to the left of it, a,
-    * and two pixels from the previous row, b and c:
-    *   prev: c b
-    *   row:  a d
-    * The Paeth function predicts d to be whichever of a, b, or c is nearest to
-    * p=a+b-c.
-    *
-    * The first pixel has no left context, and so uses an Up filter, p = b.
-    * This works naturally with our main loop's p = a+b-c if we force a and c
-    * to zero.
-    * Here we zero b and d, which become c and a respectively at the start of
-    * the loop.
-    */
-   png_debug(1, "in png_read_filter_row_paeth3_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i c, b = zero,
-           a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb >= 4) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store3(row, _mm_packus_epi16(d,d));
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-   if (rb > 0) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load3(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load3(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store3(row, _mm_packus_epi16(d,d));
-
-      prev += 3;
-      row  += 3;
-      rb   -= 3;
-   }
-}
-
-void png_read_filter_row_paeth4_sse2(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev)
-{
-   /* Paeth tries to predict pixel d using the pixel to the left of it, a,
-    * and two pixels from the previous row, b and c:
-    *   prev: c b
-    *   row:  a d
-    * The Paeth function predicts d to be whichever of a, b, or c is nearest to
-    * p=a+b-c.
-    *
-    * The first pixel has no left context, and so uses an Up filter, p = b.
-    * This works naturally with our main loop's p = a+b-c if we force a and c
-    * to zero.
-    * Here we zero b and d, which become c and a respectively at the start of
-    * the loop.
-    */
-   png_debug(1, "in png_read_filter_row_paeth4_sse2");
-   const __m128i zero = _mm_setzero_si128();
-   __m128i c, b = zero,
-           a, d = zero;
-
-   int rb = row_info->rowbytes;
-   while (rb > 0) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
-      a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
-      /* (p-a) == (a+b-c - a) == (b-c) */
-      __m128i pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      __m128i pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      __m128i pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
-                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
-                                                                     c));
-
-      /* Note `_epi8`: we need addition to wrap modulo 255. */
-      d = _mm_add_epi8(d, nearest);
-      store4(row, _mm_packus_epi16(d,d));
-
-      prev += 4;
-      row  += 4;
-      rb   -= 4;
-   }
-}
-
-#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
-#endif /* READ */
--- a/contrib/intel/intel_init.c
+++ b/contrib/intel/intel_init.c
@@ -1,54 +0,0 @@
-
-/* intel_init.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016 Google, Inc.
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/arm_init.c, which was
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
- *
- * Last changed in libpng 1.6.22 [May 26, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "../../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-
-void
-png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
-{
-   /* The techniques used to implement each of these filters in SSE operate on
-    * one pixel at a time.
-    * So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
-    * They can scale up to 6 and 8 bpp images and down to 2 bpp images,
-    * but they'd not likely have any benefit for 1bpp images.
-    * Most of these can be implemented using only MMX and 64-bit registers,
-    * but they end up a bit slower than using the equally-ubiquitous SSE2.
-   */
-   png_debug(1, "in png_init_filter_functions_sse2");
-   if (bpp == 3)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-         png_read_filter_row_paeth3_sse2;
-   }
-   else if (bpp == 4)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-          png_read_filter_row_paeth4_sse2;
-   }
-
-   /* No need optimize PNG_FILTER_VALUE_UP.  The compiler should
-    * autovectorize.
-    */
-}
-
-#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
-#endif /* PNG_READ_SUPPORTED */
--- a/contrib/intel/intel_sse.patch
+++ b/contrib/intel/intel_sse.patch
@@ -1,190 +0,0 @@
-diff --git a/configure.ac b/configure.ac
--- a/configure.ac	2016-08-29 11:46:27.000000000 -0400
-+++ b/configure.ac	2016-08-29 16:57:03.866355018 -0400
-@@ -386,16 +386,51 @@ AC_ARG_ENABLE([mips-msa],
- # future host CPU does not match 'mips*')
- 
- AM_CONDITIONAL([PNG_MIPS_MSA],
-    [test "$enable_mips_msa" != 'no' &&
-     case "$host_cpu" in
-       mipsel*|mips64el*) :;;
-     esac])
- 
-+# INTEL
-+# =====
-+#
-+# INTEL SSE (SIMD) support.
-+
-+AC_ARG_ENABLE([intel-sse],
-+   AS_HELP_STRING([[[--enable-intel-sse]]],
-+      [Enable Intel SSE optimizations: =no/off, yes/on:]
-+      [no/off: disable the optimizations;]
-+      [yes/on: enable the optimizations.]
-+      [If not specified: determined by the compiler.]),
-+   [case "$enableval" in
-+      no|off)
-+         # disable the default enabling:
-+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
-+                   [Disable Intel SSE optimizations])
-+         # Prevent inclusion of the assembler files below:
-+         enable_intel_sse=no;;
-+      yes|on)
-+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
-+                   [Enable Intel SSE optimizations]);;
-+      *)
-+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
-+   esac])
-+
-+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
-+# or where Intel optimizations were explicitly requested (this allows a
-+# fallback if a future host CPU does not match 'x86*')
-+AM_CONDITIONAL([PNG_INTEL_SSE],
-+   [test "$enable_intel_sse" != 'no' &&
-+    case "$host_cpu" in
-+      i?86|x86_64) :;;
-+      *)    test "$enable_intel_sse" != '';;
-+    esac])
-+
- AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
- 
- # Config files, substituting as above
- AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
- AC_CONFIG_FILES([libpng-config:libpng-config.in],
-    [chmod +x libpng-config])
- 
- AC_OUTPUT
-diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am	2016-08-29 11:46:27.000000000 -0400
-+++ b/Makefile.am	2016-08-29 16:57:45.955528215 -0400
-@@ -97,16 +97,21 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SO
- 	arm/filter_neon.S arm/filter_neon_intrinsics.c
- endif
- 
- if PNG_MIPS_MSA
- libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
- 	mips/filter_msa_intrinsics.c
- endif
- 
-+if PNG_INTEL_SSE
-+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
-+    contrib/intel/filter_sse2_intrinsics.c
-+endif
-+
- nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
- 
- libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
- 	-version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
- 
- if HAVE_LD_VERSION_SCRIPT
- #   Versioned symbols and restricted exports
- if HAVE_SOLARIS_LD
-diff --git a/pngpriv.h b/pngpriv.h
--- debug16/pngpriv.h	2016-08-30 10:46:36.000000000 -0400
-+++ libpng16/pngpriv.h	2016-08-30 11:57:25.672280202 -0400
-@@ -185,16 +185,52 @@
- #ifndef PNG_MIPS_MSA_OPT
- #  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
- #     define PNG_MIPS_MSA_OPT 2
- #  else
- #     define PNG_MIPS_MSA_OPT 0
- #  endif
- #endif
- 
-+#ifndef PNG_INTEL_SSE_OPT
-+#   ifdef PNG_INTEL_SSE
-+      /* Only check for SSE if the build configuration has been modified to
-+       * enable SSE optimizations.  This means that these optimizations will
-+       * be off by default.  See contrib/intel for more details.
-+       */
-+#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
-+       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
-+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
-+#         define PNG_INTEL_SSE_OPT 1
-+#      endif
-+#   endif
-+#endif
-+
-+#if PNG_INTEL_SSE_OPT > 0
-+#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
-+#      if defined(__SSE4_1__) || defined(__AVX__)
-+          /* We are not actually using AVX, but checking for AVX is the best
-+             way we can detect SSE4.1 and SSSE3 on MSVC.
-+          */
-+#         define PNG_INTEL_SSE_IMPLEMENTATION 3
-+#      elif defined(__SSSE3__)
-+#         define PNG_INTEL_SSE_IMPLEMENTATION 2
-+#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
-+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
-+#         define PNG_INTEL_SSE_IMPLEMENTATION 1
-+#      else
-+#         define PNG_INTEL_SSE_IMPLEMENTATION 0
-+#      endif
-+#   endif
-+
-+#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
-+#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
-+#   endif
-+#endif
-+
- #if PNG_MIPS_MSA_OPT > 0
- #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
- #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
- #     if defined(__mips_msa)
- #        if defined(__clang__)
- #        elif defined(__GNUC__)
- #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
- #              define PNG_MIPS_MSA_IMPLEMENTATION 2
-@@ -1232,16 +1268,31 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
- PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
-     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
- PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
-     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
- PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
-     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
- #endif
- 
-+#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
-+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-+#endif
-+
- /* Choose the best filter to use and filter the row data */
- PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
-     png_row_infop row_info),PNG_EMPTY);
- 
- #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
- PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
-    png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
-    /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
-@@ -1967,16 +2018,21 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_O
- PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
-    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
- #endif
- 
- #if PNG_MIPS_MSA_OPT > 0
- PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
-    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
- #endif
-+
-+#  if PNG_INTEL_SSE_IMPLEMENTATION > 0
-+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
-+   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
-+#  endif
- #endif
- 
- PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
-    png_const_charp key, png_bytep new_key), PNG_EMPTY);
- 
- /* Maintainer: Put new private prototypes here ^ */
- 
- #include "pngdebug.h"
--- a/contrib/libtests/pngimage.c
+++ b/contrib/libtests/pngimage.c
@@ -1,8 +1,8 @@
 /* pngimage.c
 *
- * Copyright (c) 2015,2016 John Cunningham Bowler
+ * Copyright (c) 2015 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.20 [December 3, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -36,28 +36,8 @@
 #  include <setjmp.h> /* because png.h did *not* include this */
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
-#if PNG_LIBPNG_VER < 10700
-   /* READ_PNG and WRITE_PNG were not defined, so: */
-#  ifdef PNG_INFO_IMAGE_SUPPORTED
-#     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-#        define PNG_READ_PNG_SUPPORTED
-#     endif /* SEQUENTIAL_READ */
-#     ifdef PNG_WRITE_SUPPORTED
-#        define PNG_WRITE_PNG_SUPPORTED
-#     endif /* WRITE */
-#  endif /* INFO_IMAGE */
-#endif /* pre 1.7.0 */
-
-#ifdef PNG_READ_PNG_SUPPORTED
+#if defined(PNG_INFO_IMAGE_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)\
+    && (defined(PNG_READ_PNG_SUPPORTED) || PNG_LIBPNG_VER < 10700)
 /* If a transform is valid on both read and write this implies that if the
 * transform is applied to read it must also be applied on write to produce
 * meaningful data.  This is because these transforms when performed on read
@@ -406,7 +386,7 @@ buffer_destroy(struct buffer *buffer)
   buffer_destroy_list(list);
 }

-#ifdef PNG_WRITE_PNG_SUPPORTED
+#ifdef PNG_WRITE_SUPPORTED
 static void
 buffer_start_write(struct buffer *buffer)
 {
@@ -576,7 +556,7 @@ struct display
   png_structp    read_pp;
   png_infop      read_ip;

-#  ifdef PNG_WRITE_PNG_SUPPORTED
+#  ifdef PNG_WRITE_SUPPORTED
      /* Used to write a new image (the original info_ptr is used) */
      png_structp   write_pp;
      struct buffer written_file;   /* where the file gets written */
@@ -603,7 +583,7 @@ display_init(struct display *dp)
   dp->read_ip = NULL;
   buffer_init(&dp->original_file);

-#  ifdef PNG_WRITE_PNG_SUPPORTED
+#  ifdef PNG_WRITE_SUPPORTED
      dp->write_pp = NULL;
      buffer_init(&dp->written_file);
 #  endif
@@ -616,7 +596,7 @@ display_clean_read(struct display *dp)
      png_destroy_read_struct(&dp->read_pp, &dp->read_ip, NULL);
 }

-#ifdef PNG_WRITE_PNG_SUPPORTED
+#ifdef PNG_WRITE_SUPPORTED
 static void
 display_clean_write(struct display *dp)
 {
@@ -628,7 +608,7 @@ display_clean_write(struct display *dp)
 static void
 display_clean(struct display *dp)
 {
-#  ifdef PNG_WRITE_PNG_SUPPORTED
+#  ifdef PNG_WRITE_SUPPORTED
      display_clean_write(dp);
 #  endif
   display_clean_read(dp);
@@ -646,7 +626,7 @@ static void
 display_destroy(struct display *dp)
 {
    /* Release any memory held in the display. */
-#  ifdef PNG_WRITE_PNG_SUPPORTED
+#  ifdef PNG_WRITE_SUPPORTED
      buffer_destroy(&dp->written_file);
 #  endif

@@ -1093,7 +1073,6 @@ compare_read(struct display *dp, int applied_transforms)
      }

      else
-#     ifdef PNG_sBIT_SUPPORTED
      {
         unsigned long y;
         int bpp;   /* bits-per-pixel then bytes-per-pixel */
@@ -1255,16 +1234,12 @@ compare_read(struct display *dp, int applied_transforms)
            }
         } /* for y */
      }
-#     else /* !sBIT */
-         display_log(dp, INTERNAL_ERROR,
-               "active shift transform but no sBIT support");
-#     endif /* !sBIT */
   }

   return 1; /* compare succeeded */
 }

-#ifdef PNG_WRITE_PNG_SUPPORTED
+#ifdef PNG_WRITE_SUPPORTED
 static void
 buffer_write(struct display *dp, struct buffer *buffer, png_bytep data,
   png_size_t size)
@@ -1363,7 +1338,7 @@ write_png(struct display *dp, png_infop ip, int transforms)
    */
   display_clean_write(dp);
 }
-#endif /* WRITE_PNG */
+#endif /* WRITE_SUPPORTED */

 static int
 skip_transform(struct display *dp, int tr)
@@ -1425,7 +1400,7 @@ test_one_file(struct display *dp, const char *filename)
         return; /* no point testing more */
   }

-#ifdef PNG_WRITE_PNG_SUPPORTED
+#ifdef PNG_WRITE_SUPPORTED
   /* Second test: write the original PNG data out to a new file (to test the
    * write side) then read the result back in and make sure that it hasn't
    * changed.
@@ -1466,7 +1441,7 @@ test_one_file(struct display *dp, const char *filename)
          * out and read it back in again (without the reversible transforms)
          * we should get back to the place where we started.
          */
-#ifdef PNG_WRITE_PNG_SUPPORTED
+#ifdef PNG_WRITE_SUPPORTED
         if ((current & write_transforms) == current)
         {
            /* All transforms reversible: write the PNG with the transformations
@@ -1702,11 +1677,11 @@ main(const int argc, const char * const * const argv)
      return errors != 0;
   }
 }
-#else /* !READ_PNG */
+#else /* !INFO_IMAGE || !SEQUENTIAL_READ || !READ_PNG*/
 int
 main(void)
 {
   fprintf(stderr, "pngimage: no support for png_read/write_image\n");
-   return SKIP;
+   return 77;
 }
 #endif
--- a/contrib/libtests/pngstest.c
+++ b/contrib/libtests/pngstest.c
@@ -1,9 +1,9 @@
 /*-
 * pngstest.c
 *
- * Copyright (c) 2013-2016 John Cunningham Bowler
+ * Copyright (c) 2013-2015 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -35,15 +35,6 @@
 #  include "../../png.h"
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* Else nothing can be done */
 #include "../tools/sRGB.h"

@@ -108,18 +99,10 @@ make_random_bytes(png_uint_32* seed, void* pv, size_t size)
   seed[1] = u1;
 }

-static png_uint_32 color_seed[2];
-
-static void
-reseed(void)
-{
-   color_seed[0] = 0x12345678U;
-   color_seed[1] = 0x9abcdefU;
-}
-
 static void
 random_color(png_colorp color)
 {
+   static png_uint_32 color_seed[2] = { 0x12345678, 0x9abcdef };
   make_random_bytes(color_seed, color, sizeof *color);
 }

@@ -324,7 +307,7 @@ compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
 }
 #endif /* unused */

-#define USE_FILE 1       /* else memory */
+#define READ_FILE 1      /* else memory */
 #define USE_STDIO 2      /* else use file name */
 #define STRICT 4         /* fail on warnings too */
 #define VERBOSE 8
@@ -333,19 +316,16 @@ compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
 #define ACCUMULATE 64
 #define FAST_WRITE 128
 #define sRGB_16BIT 256
-#define NO_RESEED  512   /* do not reseed on each new file */
-#define GBG_ERROR 1024   /* do not ignore the gamma+background_rgb_to_gray
-                          * libpng warning. */

 static void
 print_opts(png_uint_32 opts)
 {
-   if (opts & USE_FILE)
+   if (opts & READ_FILE)
      printf(" --file");
   if (opts & USE_STDIO)
      printf(" --stdio");
-   if (!(opts & STRICT))
-      printf(" --nostrict");
+   if (opts & STRICT)
+      printf(" --strict");
   if (opts & VERBOSE)
      printf(" --verbose");
   if (opts & KEEP_TMPFILES)
@@ -358,12 +338,6 @@ print_opts(png_uint_32 opts)
      printf(" --slow");
   if (opts & sRGB_16BIT)
      printf(" --sRGB-16bit");
-   if (opts & NO_RESEED)
-      printf(" --noreseed");
-#if PNG_LIBPNG_VER < 10700 /* else on by default */
-   if (opts & GBG_ERROR)
-      printf(" --fault-gbg-warning");
-#endif
 }

 #define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
@@ -767,15 +741,8 @@ checkopaque(Image *image)
      return logerror(image, image->file_name, ": opaque not NULL", "");
   }

-   /* Separate out the gamma+background_rgb_to_gray warning because it may
-    * produce opaque component errors:
-    */
-   else if (image->image.warning_or_error != 0 &&
-            (strcmp(image->image.message,
-               "libpng does not support gamma+background+rgb_to_gray") == 0 ?
-                  (image->opts & GBG_ERROR) != 0 : (image->opts & STRICT) != 0))
-      return logerror(image, image->file_name, (image->opts & GBG_ERROR) != 0 ?
-                      " --fault-gbg-warning" : " --strict", "");
+   else if (image->image.warning_or_error != 0 && (image->opts & STRICT) != 0)
+      return logerror(image, image->file_name, " --strict", "");

   else
      return 1;
@@ -3041,14 +3008,14 @@ read_file(Image *image, png_uint_32 format, png_const_colorp background)
 static int
 read_one_file(Image *image)
 {
-   if (!(image->opts & USE_FILE) || (image->opts & USE_STDIO))
+   if (!(image->opts & READ_FILE) || (image->opts & USE_STDIO))
   {
      /* memory or stdio. */
      FILE *f = fopen(image->file_name, "rb");

      if (f != NULL)
      {
-         if (image->opts & USE_FILE)
+         if (image->opts & READ_FILE)
            image->input_file = f;

         else /* memory */
@@ -3129,8 +3096,7 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

   if (image->opts & USE_STDIO)
   {
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
-#ifndef __COVERITY__
+#ifndef PNG_USE_MKSTEMP
      FILE *f = tmpfile();
 #else
      /* Experimental. Coverity says tmpfile() is insecure because it
@@ -3192,14 +3158,10 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

      else
         return logerror(image, "tmpfile", ": open: ", strerror(errno));
-#else /* SIMPLIFIED_WRITE_STDIO */
-      return logerror(image, "tmpfile", ": open: unsupported", "");
-#endif /* SIMPLIFIED_WRITE_STDIO */
   }

-   else if (image->opts & USE_FILE)
+   else
   {
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
      static int counter = 0;
      char name[32];

@@ -3219,51 +3181,6 @@ write_one_file(Image *output, Image *image, int convert_to_8bit)

      else
         return logerror(image, name, ": write failed", "");
-#else /* SIMPLIFIED_WRITE_STDIO */
-      return logerror(image, "stdio", ": open: unsupported", "");
-#endif /* SIMPLIFIED_WRITE_STDIO */
-   }
-
-   else /* use memory */
-   {
-      png_alloc_size_t size;
-
-      if (png_image_write_get_memory_size(image->image, size, convert_to_8bit,
-               image->buffer+16, (png_int_32)image->stride, image->colormap))
-      {
-         /* This is non-fatal but ignoring it was causing serious problems in
-          * the macro to be ignored:
-          */
-         if (size > PNG_IMAGE_PNG_SIZE_MAX(image->image))
-            return logerror(image, "memory", ": PNG_IMAGE_SIZE_MAX wrong", "");
-
-         initimage(output, image->opts, "memory", image->stride_extra);
-         output->input_memory = malloc(size);
-
-         if (output->input_memory != NULL)
-         {
-            output->input_memory_size = size;
-
-            if (png_image_write_to_memory(&image->image, output->input_memory,
-                  &output->input_memory_size, convert_to_8bit, image->buffer+16,
-                  (png_int_32)image->stride, image->colormap))
-            {
-               /* This is also non-fatal but it safes safer to error out anyway:
-                */
-               if (size != output->input_memory_size)
-                  return logerror(image, "memory", ": memory size wrong", "");
-            }
-
-            else
-               return logerror(image, "memory", ": write failed", "");
-         }
-
-         else
-            return logerror(image, "memory", ": out of memory", "");
-      }
-
-      else
-         return logerror(image, "memory", ": get size:", "");
   }

   /* 'output' has an initialized temporary image, read this back in and compare
@@ -3439,8 +3356,6 @@ test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
   int result;
   Image image;

-   if (!(opts & NO_RESEED))
-      reseed(); /* ensure that the random numbers don't depend on file order */
   newimage(&image);
   initimage(&image, opts, file_name, stride_extra);
   result = read_one_file(&image);
@@ -3478,7 +3393,7 @@ test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
 int
 main(int argc, char **argv)
 {
-   png_uint_32 opts = FAST_WRITE | STRICT;
+   png_uint_32 opts = FAST_WRITE;
   format_list formats;
   const char *touch = NULL;
   int log_pass = 0;
@@ -3487,17 +3402,11 @@ main(int argc, char **argv)
   int retval = 0;
   int c;

-#if PNG_LIBPNG_VER >= 10700
-      /* This error should not exist in 1.7 or later: */
-      opts |= GBG_ERROR;
-#endif
-
   init_sRGB_to_d();
 #if 0
   init_error_via_linear();
 #endif
   format_init(&formats);
-   reseed(); /* initialize random number seeds */

   for (c=1; c<argc; ++c)
   {
@@ -3512,17 +3421,17 @@ main(int argc, char **argv)
      }
      else if (strcmp(arg, "--file") == 0)
 #        ifdef PNG_STDIO_SUPPORTED
-            opts |= USE_FILE;
+            opts |= READ_FILE;
 #        else
-            return SKIP; /* skipped: no support */
+            return 77; /* skipped: no support */
 #        endif
      else if (strcmp(arg, "--memory") == 0)
-         opts &= ~USE_FILE;
+         opts &= ~READ_FILE;
      else if (strcmp(arg, "--stdio") == 0)
 #        ifdef PNG_STDIO_SUPPORTED
            opts |= USE_STDIO;
 #        else
-            return SKIP; /* skipped: no support */
+            return 77; /* skipped: no support */
 #        endif
      else if (strcmp(arg, "--name") == 0)
         opts &= ~USE_STDIO;
@@ -3548,16 +3457,10 @@ main(int argc, char **argv)
         opts &= ~KEEP_GOING;
      else if (strcmp(arg, "--strict") == 0)
         opts |= STRICT;
-      else if (strcmp(arg, "--nostrict") == 0)
-         opts &= ~STRICT;
      else if (strcmp(arg, "--sRGB-16bit") == 0)
         opts |= sRGB_16BIT;
      else if (strcmp(arg, "--linear-16bit") == 0)
         opts &= ~sRGB_16BIT;
-      else if (strcmp(arg, "--noreseed") == 0)
-         opts |= NO_RESEED;
-      else if (strcmp(arg, "--fault-gbg-warning") == 0)
-         opts |= GBG_ERROR;
      else if (strcmp(arg, "--tmpfile") == 0)
      {
         if (c+1 < argc)
@@ -3814,6 +3717,6 @@ int main(void)
 {
   fprintf(stderr, "pngstest: no read support in libpng, test skipped\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
--- a/contrib/libtests/pngunknown.c
+++ b/contrib/libtests/pngunknown.c
@@ -1,8 +1,8 @@

 /* pngunknown.c - test the read side unknown chunk handling
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
- * Copyright (c) 2015,2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.10 [March 6, 2014]
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
 * This code is released under the libpng license.
@@ -30,21 +30,10 @@
 #  include "../../png.h"
 #endif

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
-
 /* Since this program tests the ability to change the unknown chunk handling
 * these must be defined:
 */
 #if defined(PNG_SET_UNKNOWN_CHUNKS_SUPPORTED) &&\
-   defined(PNG_STDIO_SUPPORTED) &&\
   defined(PNG_READ_SUPPORTED)

 /* One of these must be defined to allow us to find out what happened.  It is
@@ -626,7 +615,7 @@ get_unknown(display *d, png_infop info_ptr, int after_IDAT)

   return flags;
 }
-#else /* SAVE_UNKNOWN_CHUNKS */
+#else
 static png_uint_32
 get_unknown(display *d, png_infop info_ptr, int after_IDAT)
   /* Otherwise this will return the cached values set by any user callback */
@@ -645,8 +634,8 @@ get_unknown(display *d, png_infop info_ptr, int after_IDAT)
       * a check to ensure the logic is correct.
       */
 #     error No store support and no user chunk support, this will not work
-#  endif /* READ_USER_CHUNKS */
-#endif /* SAVE_UNKNOWN_CHUNKS */
+#  endif
+#endif

 static int
 check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
@@ -1012,20 +1001,6 @@ perform_one_test(FILE *fp, int argc, const char **argv,

   def = check(fp, argc, argv, flags[1], d, set_callback);

-   /* If IDAT is being handled as unknown the image read is skipped and all the
-    * IDATs after the first end up in the end info struct, so in this case add
-    * IDAT to the list of unknowns.  (Do this after 'check' above sets the
-    * chunk_info 'keep' fields.)
-    *
-    * Note that the flag setting has to be in the 'known' field to avoid
-    * triggering the consistency check below and the flag must only be set if
-    * there are multiple IDATs, so if the check above did find an unknown IDAT
-    * after IDAT.
-    */
-   if (chunk_info[0/*IDAT*/].keep != PNG_HANDLE_CHUNK_AS_DEFAULT &&
-       (flags[1][3] & PNG_INFO_IDAT) != 0)
-      flags[0][2] |= PNG_INFO_IDAT;
-
   /* Chunks should either be known or unknown, never both and this should apply
    * whether the chunk is before or after the IDAT (actually, the app can
    * probably change this by swapping the handling after the image, but this
@@ -1270,7 +1245,7 @@ main(void)
   fprintf(stderr,
      " test ignored: no support to find out about unknown chunks\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* READ_USER_CHUNKS || SAVE_UNKNOWN_CHUNKS */

@@ -1281,6 +1256,6 @@ main(void)
   fprintf(stderr,
      " test ignored: no support to modify unknown chunk handling\n");
   /* So the test is skipped: */
-   return SKIP;
+   return 77;
 }
 #endif /* SET_UNKNOWN_CHUNKS && READ*/
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,7 +1,7 @@

 /* pngvalid.c - validate libpng by constructing then reading png files.
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.21 [January 15, 2016]
 * Copyright (c) 2014-2016 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
@@ -62,10 +62,10 @@
 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
 */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
+#if PNG_LIBPNG_VER < 10601
 #  define SKIP 0
+#else
+#  define SKIP 77
 #endif

 /* pngvalid requires write support and one of the fixed or floating point APIs.
@@ -131,17 +131,6 @@ typedef png_byte *png_const_bytep;
 #include <string.h> /* For memcpy, memset */
 #include <math.h>   /* For floor */

-/* Convenience macros. */
-#define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
-#define CHUNK_IHDR CHUNK(73,72,68,82)
-#define CHUNK_PLTE CHUNK(80,76,84,69)
-#define CHUNK_IDAT CHUNK(73,68,65,84)
-#define CHUNK_IEND CHUNK(73,69,78,68)
-#define CHUNK_cHRM CHUNK(99,72,82,77)
-#define CHUNK_gAMA CHUNK(103,65,77,65)
-#define CHUNK_sBIT CHUNK(115,66,73,84)
-#define CHUNK_sRGB CHUNK(115,82,71,66)
-
 /* Unused formal parameter errors are removed using the following macro which is
 * expected to have no bad effects on performance.
 */
@@ -308,33 +297,48 @@ randomize(void *pv, size_t size)

 #define R8(this) randomize(&(this), sizeof (this))

-#ifdef PNG_READ_SUPPORTED
-static png_byte
-random_byte(void)
+static void r16(png_uint_16p p16, size_t count)
 {
-   unsigned char b1[1];
-   randomize(b1, sizeof b1);
-   return b1[0];
-}
-#endif /* READ */
+   size_t i;

-static png_uint_16
-random_u16(void)
-{
-   unsigned char b2[2];
-   randomize(b2, sizeof b2);
-   return png_get_uint_16(b2);
+   for (i=0; i<count; ++i)
+   {
+      unsigned char b2[2];
+      randomize(b2, sizeof b2);
+      *p16++ = png_get_uint_16(b2);
+   }
 }

+#ifdef __COVERITY__
+#  define R16(this)\
+   r16(&(this), (sizeof (this))/2U/*(sizeof (png_uint_16))*/)
+#else
+#  define R16(this)\
+   r16(&(this), (sizeof (this))/(sizeof (png_uint_16)))
+#endif
+
 #if defined PNG_READ_RGB_TO_GRAY_SUPPORTED ||\
    defined PNG_READ_FILLER_SUPPORTED
-static png_uint_32
-random_u32(void)
+static void r32(png_uint_32p p32, size_t count)
 {
-   unsigned char b4[4];
-   randomize(b4, sizeof b4);
-   return png_get_uint_32(b4);
+   size_t i;
+
+   for (i=0; i<count; ++i)
+   {
+      unsigned char b4[4];
+      randomize(b4, sizeof b4);
+      *p32++ = png_get_uint_32(b4);
+   }
 }
+
+#ifdef __COVERITY__
+#  define R32(this)\
+   r32(&(this), (sizeof (this))/4U/*(sizeof (png_uint_32))*/)
+#else
+#  define R32(this)\
+   r32(&(this), (sizeof (this))/(sizeof (png_uint_32)))
+#endif
+
 #endif /* READ_FILLER || READ_RGB_TO_GRAY */

 #endif /* READ || WRITE_tRNS || WRITE_FILTER */
@@ -344,7 +348,11 @@ random_u32(void)
 static unsigned int
 random_mod(unsigned int max)
 {
-   return random_u16() % max; /* 0 .. max-1 */
+   png_uint_16 x;
+
+   R16(x);
+
+   return x % max; /* 0 .. max-1 */
 }
 #endif /* READ_TRANSFORMS || WRITE_FILTER */

@@ -353,7 +361,11 @@ random_mod(unsigned int max)
 static int
 random_choice(void)
 {
-   return random_byte() & 1;
+   unsigned char x;
+
+   R8(x);
+
+   return x & 1;
 }
 #endif /* READ_RGB_TO_GRAY || READ_FILLER */

@@ -709,8 +721,6 @@ typedef struct png_store_file
 {
   struct png_store_file*  next;      /* as many as you like... */
   char                    name[FILE_NAME_SIZE];
-   unsigned int            IDAT_bits; /* Number of bits in IDAT size */
-   png_uint_32             IDAT_size; /* Total size of IDAT data */
   png_uint_32             id;        /* must be correct (see FILEID) */
   png_size_t              datacount; /* In this (the last) buffer */
   png_store_buffer        data;      /* Last buffer in file */
@@ -766,13 +776,6 @@ typedef struct png_store
   char               test[128];      /* Name of test */
   char               error[256];

-   /* Share fields */
-   png_uint_32        chunklen; /* Length of chunk+overhead (chunkpos >= 8) */
-   png_uint_32        chunktype;/* Type of chunk (valid if chunkpos >= 4) */
-   png_uint_32        chunkpos; /* Position in chunk */
-   png_uint_32        IDAT_size;/* Accumulated IDAT size in .new */
-   unsigned int       IDAT_bits;/* Cache of the file store value */
-
   /* Read fields */
   png_structp        pread;    /* Used to read a saved file */
   png_infop          piread;
@@ -782,9 +785,6 @@ typedef struct png_store
   png_byte*          image;    /* Buffer for reading interlaced images */
   png_size_t         cb_image; /* Size of this buffer */
   png_size_t         cb_row;   /* Row size of the image(s) */
-   uLong              IDAT_crc;
-   png_uint_32        IDAT_len; /* Used when re-chunking IDAT chunks */
-   png_uint_32        IDAT_pos; /* Used when re-chunking IDAT chunks */
   png_uint_32        image_h;  /* Number of rows in a single image */
   store_pool         read_memory_pool;

@@ -871,11 +871,6 @@ store_init(png_store* ps)
   ps->pwrite = NULL;
   ps->piwrite = NULL;
   ps->writepos = 0;
-   ps->chunkpos = 8;
-   ps->chunktype = 0;
-   ps->chunklen = 16;
-   ps->IDAT_size = 0;
-   ps->IDAT_bits = 0;
   ps->new.prev = NULL;
   ps->palette = NULL;
   ps->npalette = 0;
@@ -898,11 +893,6 @@ store_freenew(png_store *ps)
 {
   store_freebuffer(&ps->new);
   ps->writepos = 0;
-   ps->chunkpos = 8;
-   ps->chunktype = 0;
-   ps->chunklen = 16;
-   ps->IDAT_size = 0;
-   ps->IDAT_bits = 0;
   if (ps->palette != NULL)
   {
      free(ps->palette);
@@ -916,6 +906,9 @@ store_storenew(png_store *ps)
 {
   png_store_buffer *pb;

+   if (ps->writepos != STORE_BUFFER_SIZE)
+      png_error(ps->pwrite, "invalid store call");
+
   pb = voidcast(png_store_buffer*, malloc(sizeof *pb));

   if (pb == NULL)
@@ -946,52 +939,21 @@ store_freefile(png_store_file **ppf)
   }
 }

-static unsigned int
-bits_of(png_uint_32 num)
-{
-   /* Return the number of bits in 'num' */
-   unsigned int b = 0;
-
-   if (num & 0xffff0000U)  b += 16U, num >>= 16;
-   if (num & 0xff00U)      b += 8U, num >>= 8;
-   if (num & 0xf0U)        b += 4U, num >>= 4;
-   if (num & 0xcU)         b += 2U, num >>= 2;
-   if (num & 0x2U)         ++b, num >>= 1;
-   if (num)                ++b;
-
-   return b; /* 0..32 */
-}
-
 /* Main interface to file storeage, after writing a new PNG file (see the API
 * below) call store_storefile to store the result with the given name and id.
 */
 static void
 store_storefile(png_store *ps, png_uint_32 id)
 {
-   png_store_file *pf;
-
-   if (ps->chunkpos != 0U || ps->chunktype != 0U || ps->chunklen != 0U ||
-       ps->IDAT_size == 0)
-      png_error(ps->pwrite, "storefile: incomplete write");
-
-   pf = voidcast(png_store_file*, malloc(sizeof *pf));
+   png_store_file *pf = voidcast(png_store_file*, malloc(sizeof *pf));
   if (pf == NULL)
      png_error(ps->pwrite, "storefile: OOM");
   safecat(pf->name, sizeof pf->name, 0, ps->wname);
   pf->id = id;
   pf->data = ps->new;
   pf->datacount = ps->writepos;
-   pf->IDAT_size = ps->IDAT_size;
-   pf->IDAT_bits = bits_of(ps->IDAT_size);
-   /* Because the IDAT always has zlib header stuff this must be true: */
-   if (pf->IDAT_bits == 0U)
-      png_error(ps->pwrite, "storefile: 0 sized IDAT");
   ps->new.prev = NULL;
   ps->writepos = 0;
-   ps->chunkpos = 8;
-   ps->chunktype = 0;
-   ps->chunklen = 16;
-   ps->IDAT_size = 0;
   pf->palette = ps->palette;
   pf->npalette = ps->npalette;
   ps->palette = 0;
@@ -1257,119 +1219,32 @@ store_image_check(const png_store* ps, png_const_structp pp, int iImage)
 }
 #endif /* PNG_READ_SUPPORTED */

-static int
-valid_chunktype(png_uint_32 chunktype)
-{
-   /* Each byte in the chunk type must be in one of the ranges 65..90, 97..122
-    * (both inclusive), so:
-    */
-   unsigned int i;
-
-   for (i=0; i<4; ++i)
-   {
-      unsigned int c = chunktype & 0xffU;
-
-      if (!((c >= 65U && c <= 90U) || (c >= 97U && c <= 122U)))
-         return 0;
-
-      chunktype >>= 8;
-   }
-
-   return 1; /* It's valid */
-}
-
 static void PNGCBAPI
 store_write(png_structp ppIn, png_bytep pb, png_size_t st)
 {
   png_const_structp pp = ppIn;
   png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
-   size_t writepos = ps->writepos;
-   png_uint_32 chunkpos = ps->chunkpos;
-   png_uint_32 chunktype = ps->chunktype;
-   png_uint_32 chunklen = ps->chunklen;

   if (ps->pwrite != pp)
      png_error(pp, "store state damaged");

-   /* Technically this is legal, but in practice libpng never writes more than
-    * the maximum chunk size at once so if it happens something weird has
-    * changed inside libpng (probably).
-    */
-   if (st > 0x7fffffffU)
-      png_error(pp, "unexpected write size");
-
-   /* Now process the bytes to be written.  Do this in units of the space in the
-    * output (write) buffer or, at the start 4 bytes for the chunk type and
-    * length limited in any case by the amount of data.
-    */
   while (st > 0)
   {
-      if (writepos >= STORE_BUFFER_SIZE)
-         store_storenew(ps), writepos = 0;
+      size_t cb;

-      if (chunkpos < 4)
-      {
-         png_byte b = *pb++;
-         --st;
-         chunklen = (chunklen << 8) + b;
-         ps->new.buffer[writepos++] = b;
-         ++chunkpos;
-      }
+      if (ps->writepos >= STORE_BUFFER_SIZE)
+         store_storenew(ps);

-      else if (chunkpos < 8)
-      {
-         png_byte b = *pb++;
-         --st;
-         chunktype = (chunktype << 8) + b;
-         ps->new.buffer[writepos++] = b;
+      cb = st;

-         if (++chunkpos == 8)
-         {
-            chunklen &= 0xffffffffU;
-            if (chunklen > 0x7fffffffU)
-               png_error(pp, "chunk length too great");
+      if (cb > STORE_BUFFER_SIZE - ps->writepos)
+         cb = STORE_BUFFER_SIZE - ps->writepos;

-            chunktype &= 0xffffffffU;
-            if (chunktype == CHUNK_IDAT)
-            {
-               if (chunklen > ~ps->IDAT_size)
-                  png_error(pp, "pngvalid internal image too large");
-
-               ps->IDAT_size += chunklen;
-            }
-
-            else if (!valid_chunktype(chunktype))
-               png_error(pp, "invalid chunk type");
-
-            chunklen += 12; /* for header and CRC */
-         }
-      }
-
-      else /* chunkpos >= 8 */
-      {
-         png_size_t cb = st;
-
-         if (cb > STORE_BUFFER_SIZE - writepos)
-            cb = STORE_BUFFER_SIZE - writepos;
-
-         if (cb  > chunklen - chunkpos/* bytes left in chunk*/)
-            cb = (png_size_t)/*SAFE*/(chunklen - chunkpos);
-
-         memcpy(ps->new.buffer + writepos, pb, cb);
-         chunkpos += (png_uint_32)/*SAFE*/cb;
-         pb += cb;
-         writepos += cb;
-         st -= cb;
-
-         if (chunkpos >= chunklen) /* must be equal */
-            chunkpos = chunktype = chunklen = 0;
-      }
-   } /* while (st > 0) */
-
-   ps->writepos = writepos;
-   ps->chunkpos = chunkpos;
-   ps->chunktype = chunktype;
-   ps->chunklen = chunklen;
+      memcpy(ps->new.buffer + ps->writepos, pb, cb);
+      pb += cb;
+      st -= cb;
+      ps->writepos += cb;
+   }
 }

 static void PNGCBAPI
@@ -1389,6 +1264,7 @@ store_read_buffer_size(png_store *ps)
   return ps->current->datacount;
 }

+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 /* Return total bytes available for read. */
 static size_t
 store_read_buffer_avail(png_store *ps)
@@ -1413,6 +1289,7 @@ store_read_buffer_avail(png_store *ps)

   return 0;
 }
+#endif

 static int
 store_read_buffer_next(png_store *ps)
@@ -1464,240 +1341,6 @@ store_read_imp(png_store *ps, png_bytep pb, png_size_t st)
   }
 }

-static png_size_t
-store_read_chunk(png_store *ps, png_bytep pb, const png_size_t max,
-      const png_size_t min)
-{
-   png_uint_32 chunklen = ps->chunklen;
-   png_uint_32 chunktype = ps->chunktype;
-   png_uint_32 chunkpos = ps->chunkpos;
-   png_size_t st = max;
-
-   if (st > 0) do
-   {
-      if (chunkpos >= chunklen) /* end of last chunk */
-      {
-         png_byte buffer[8];
-
-         /* Read the header of the next chunk: */
-         store_read_imp(ps, buffer, 8U);
-         chunklen = png_get_uint_32(buffer) + 12U;
-         chunktype = png_get_uint_32(buffer+4U);
-         chunkpos = 0U; /* Position read so far */
-      }
-
-      if (chunktype == CHUNK_IDAT)
-      {
-         png_uint_32 IDAT_pos = ps->IDAT_pos;
-         png_uint_32 IDAT_len = ps->IDAT_len;
-         png_uint_32 IDAT_size = ps->IDAT_size;
-
-         /* The IDAT headers are constructed here; skip the input header. */
-         if (chunkpos < 8U)
-            chunkpos = 8U;
-
-         if (IDAT_pos == IDAT_len)
-         {
-            png_byte random = random_byte();
-
-            /* Make a new IDAT chunk, if IDAT_len is 0 this is the first IDAT,
-             * if IDAT_size is 0 this is the end.  At present this is set up
-             * using a random number so that there is a 25% chance before
-             * the start of the first IDAT chunk being 0 length.
-             */
-            if (IDAT_len == 0U) /* First IDAT */
-            {
-               switch (random & 3U)
-               {
-                  case 0U: IDAT_len = 12U; break; /* 0 bytes */
-                  case 1U: IDAT_len = 13U; break; /* 1 byte */
-                  default: IDAT_len = random_u32();
-                           IDAT_len %= IDAT_size;
-                           IDAT_len += 13U; /* 1..IDAT_size bytes */
-                           break;
-               }
-            }
-
-            else if (IDAT_size == 0U) /* all IDAT data read */
-            {
-               /* The last (IDAT) chunk should be positioned at the CRC now: */
-               if (chunkpos != chunklen-4U)
-                  png_error(ps->pread, "internal: IDAT size mismatch");
-
-               /* The only option here is to add a zero length IDAT, this
-                * happens 25% of the time.  Because of the check above
-                * chunklen-4U-chunkpos must be zero, we just need to skip the
-                * CRC now.
-                */
-               if ((random & 3U) == 0U)
-                  IDAT_len = 12U; /* Output another 0 length IDAT */
-
-               else
-               {
-                  /* End of IDATs, skip the CRC to make the code above load the
-                   * next chunk header next time round.
-                   */
-                  png_byte buffer[4];
-
-                  store_read_imp(ps, buffer, 4U);
-                  chunkpos += 4U;
-                  ps->IDAT_pos = IDAT_pos;
-                  ps->IDAT_len = IDAT_len;
-                  ps->IDAT_size = 0U;
-                  continue; /* Read the next chunk */
-               }
-            }
-
-            else
-            {
-               /* Middle of IDATs, use 'random' to determine the number of bits
-                * to use in the IDAT length.
-                */
-               IDAT_len = random_u32();
-               IDAT_len &= (1U << (1U + random % ps->IDAT_bits)) - 1U;
-               if (IDAT_len > IDAT_size)
-                  IDAT_len = IDAT_size;
-               IDAT_len += 12U; /* zero bytes may occur */
-            }
-
-            IDAT_pos = 0U;
-            ps->IDAT_crc = 0x35af061e; /* Ie: crc32(0UL, "IDAT", 4) */
-         } /* IDAT_pos == IDAT_len */
-
-         if (IDAT_pos < 8U) /* Return the header */ do
-         {
-            png_uint_32 b;
-            unsigned int shift;
-
-            if (IDAT_pos < 4U)
-               b = IDAT_len - 12U;
-
-            else
-               b = CHUNK_IDAT;
-
-            shift = 3U & IDAT_pos;
-            ++IDAT_pos;
-
-            if (shift < 3U)
-               b >>= 8U*(3U-shift);
-
-            *pb++ = 0xffU & b;
-         }
-         while (--st > 0 && IDAT_pos < 8);
-
-         else if (IDAT_pos < IDAT_len - 4U) /* I.e not the CRC */
-         {
-            if (chunkpos < chunklen-4U)
-            {
-               uInt avail = (uInt)-1;
-
-               if (avail > (IDAT_len-4U) - IDAT_pos)
-                  avail = (uInt)/*SAFE*/((IDAT_len-4U) - IDAT_pos);
-
-               if (avail > st)
-                  avail = (uInt)/*SAFE*/st;
-
-               if (avail > (chunklen-4U) - chunkpos)
-                  avail = (uInt)/*SAFE*/((chunklen-4U) - chunkpos);
-
-               store_read_imp(ps, pb, avail);
-               ps->IDAT_crc = crc32(ps->IDAT_crc, pb, avail);
-               pb += (png_size_t)/*SAFE*/avail;
-               st -= (png_size_t)/*SAFE*/avail;
-               chunkpos += (png_uint_32)/*SAFE*/avail;
-               IDAT_size -= (png_uint_32)/*SAFE*/avail;
-               IDAT_pos += (png_uint_32)/*SAFE*/avail;
-            }
-
-            else /* skip the input CRC */
-            {
-               png_byte buffer[4];
-
-               store_read_imp(ps, buffer, 4U);
-               chunkpos += 4U;
-            }
-         }
-
-         else /* IDAT crc */ do
-         {
-            uLong b = ps->IDAT_crc;
-            unsigned int shift = (IDAT_len - IDAT_pos); /* 4..1 */
-            ++IDAT_pos;
-
-            if (shift > 1U)
-               b >>= 8U*(shift-1U);
-
-            *pb++ = 0xffU & b;
-         }
-         while (--st > 0 && IDAT_pos < IDAT_len);
-
-         ps->IDAT_pos = IDAT_pos;
-         ps->IDAT_len = IDAT_len;
-         ps->IDAT_size = IDAT_size;
-      }
-
-      else /* !IDAT */
-      {
-         /* If there is still some pending IDAT data after the IDAT chunks have
-          * been processed there is a problem:
-          */
-         if (ps->IDAT_len > 0 && ps->IDAT_size > 0)
-            png_error(ps->pread, "internal: missing IDAT data");
-
-         if (chunktype == CHUNK_IEND && ps->IDAT_len == 0U)
-            png_error(ps->pread, "internal: missing IDAT");
-
-         if (chunkpos < 8U) /* Return the header */ do
-         {
-            png_uint_32 b;
-            unsigned int shift;
-
-            if (chunkpos < 4U)
-               b = chunklen - 12U;
-
-            else
-               b = chunktype;
-
-            shift = 3U & chunkpos;
-            ++chunkpos;
-
-            if (shift < 3U)
-               b >>= 8U*(3U-shift);
-
-            *pb++ = 0xffU & b;
-         }
-         while (--st > 0 && chunkpos < 8);
-
-         else /* Return chunk bytes, including the CRC */
-         {
-            png_size_t avail = st;
-
-            if (avail > chunklen - chunkpos)
-               avail = (png_size_t)/*SAFE*/(chunklen - chunkpos);
-
-            store_read_imp(ps, pb, avail);
-            pb += avail;
-            st -= avail;
-            chunkpos += (png_uint_32)/*SAFE*/avail;
-
-            /* Check for end of chunk and end-of-file; don't try to read a new
-             * chunk header at this point unless instructed to do so by 'min'.
-             */
-            if (chunkpos >= chunklen && max-st >= min &&
-                     store_read_buffer_avail(ps) == 0)
-               break;
-         }
-      } /* !IDAT */
-   }
-   while (st > 0);
-
-   ps->chunklen = chunklen;
-   ps->chunktype = chunktype;
-   ps->chunkpos = chunkpos;
-
-   return st; /* space left */
-}
-
 static void PNGCBAPI
 store_read(png_structp ppIn, png_bytep pb, png_size_t st)
 {
@@ -1707,33 +1350,26 @@ store_read(png_structp ppIn, png_bytep pb, png_size_t st)
   if (ps == NULL || ps->pread != pp)
      png_error(pp, "bad store read call");

-   store_read_chunk(ps, pb, st, st);
+   store_read_imp(ps, pb, st);
 }

 static void
 store_progressive_read(png_store *ps, png_structp pp, png_infop pi)
 {
+   /* Notice that a call to store_read will cause this function to fail because
+    * readpos will be set.
+    */
   if (ps->pread != pp || ps->current == NULL || ps->next == NULL)
      png_error(pp, "store state damaged (progressive)");

-   /* This is another Horowitz and Hill random noise generator.  In this case
-    * the aim is to stress the progressive reader with truly horrible variable
-    * buffer sizes in the range 1..500, so a sequence of 9 bit random numbers
-    * is generated.  We could probably just count from 1 to 32767 and get as
-    * good a result.
-    */
-   while (store_read_buffer_avail(ps) > 0)
+   do
   {
-      static png_uint_32 noise = 2;
-      png_size_t cb;
-      png_byte buffer[512];
+      if (ps->readpos != 0)
+         png_error(pp, "store_read called during progressive read");

-      /* Generate 15 more bits of stuff: */
-      noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff);
-      cb = noise & 0x1ff;
-      cb -= store_read_chunk(ps, buffer, cb, 1);
-      png_process_data(pp, pi, buffer, cb);
+      png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps));
   }
+   while (store_read_buffer_next(ps));
 }
 #endif /* PNG_READ_SUPPORTED */

@@ -2104,11 +1740,6 @@ store_read_reset(png_store *ps)
   ps->next = NULL;
   ps->readpos = 0;
   ps->validated = 0;
-
-   ps->chunkpos = 8;
-   ps->chunktype = 0;
-   ps->chunklen = 16;
-   ps->IDAT_size = 0;
 }

 #ifdef PNG_READ_SUPPORTED
@@ -2123,11 +1754,6 @@ store_read_set(png_store *ps, png_uint_32 id)
      {
         ps->current = pf;
         ps->next = NULL;
-         ps->IDAT_size = pf->IDAT_size;
-         ps->IDAT_bits = pf->IDAT_bits; /* just a cache */
-         ps->IDAT_len = 0;
-         ps->IDAT_pos = 0;
-         ps->IDAT_crc = 0UL;
         store_read_buffer_next(ps);
         return;
      }
@@ -2965,6 +2591,17 @@ modifier_color_encoding_is_set(const png_modifier *pm)
   return pm->current_gamma != 0;
 }

+/* Convenience macros. */
+#define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
+#define CHUNK_IHDR CHUNK(73,72,68,82)
+#define CHUNK_PLTE CHUNK(80,76,84,69)
+#define CHUNK_IDAT CHUNK(73,68,65,84)
+#define CHUNK_IEND CHUNK(73,69,78,68)
+#define CHUNK_cHRM CHUNK(99,72,82,77)
+#define CHUNK_gAMA CHUNK(103,65,77,65)
+#define CHUNK_sBIT CHUNK(115,66,73,84)
+#define CHUNK_sRGB CHUNK(115,82,71,66)
+
 /* The guts of modification are performed during a read. */
 static void
 modifier_crc(png_bytep buffer)
@@ -3004,7 +2641,7 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
      {
         static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
         case modifier_start:
-            store_read_chunk(&pm->this, pm->buffer, 8, 8); /* signature. */
+            store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */
            pm->buffer_count = 8;
            pm->buffer_position = 0;

@@ -3014,7 +2651,7 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
            break;

         case modifier_signature:
-            store_read_chunk(&pm->this, pm->buffer, 13+12, 13+12); /* IHDR */
+            store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */
            pm->buffer_count = 13+12;
            pm->buffer_position = 0;

@@ -3055,7 +2692,7 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
            {
               if (cb > st) cb = st;
               pm->flush -= cb;
-               store_read_chunk(&pm->this, pb, cb, cb);
+               store_read_imp(&pm->this, pb, cb);
               pb += cb;
               st -= cb;
               if (st == 0) return;
@@ -3072,7 +2709,7 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
               pm->pending_chunk = 0;
            }
            else
-               store_read_chunk(&pm->this, pm->buffer, 8, 8);
+               store_read_imp(&pm->this, pm->buffer, 8);

            pm->buffer_count = 8;
            pm->buffer_position = 0;
@@ -3138,8 +2775,8 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
             */
            if (len+12 <= sizeof pm->buffer)
            {
-               png_size_t s = len+12-pm->buffer_count;
-               store_read_chunk(&pm->this, pm->buffer+pm->buffer_count, s, s);
+               store_read_imp(&pm->this, pm->buffer+pm->buffer_count,
+                   len+12-pm->buffer_count);
               pm->buffer_count = len+12;

               /* Check for a modification, else leave it be. */
@@ -3680,10 +3317,10 @@ init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
      for (; i<256; ++i)
         tRNS[i] = 24;

-#ifdef PNG_WRITE_tRNS_SUPPORTED
-      if (j > 0)
-         png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
-#endif
+#     ifdef PNG_WRITE_tRNS_SUPPORTED
+         if (j > 0)
+            png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
+#     endif
   }
 }

@@ -3706,8 +3343,8 @@ set_random_tRNS(png_structp pp, png_infop pi, const png_byte colour_type,
   {
      if (bit_depth == 8)
      {
-         tRNS.red = random_u16();
-         tRNS.green = random_u16();
+         R16(tRNS.red);
+         R16(tRNS.green);
         tRNS.blue = tRNS.red ^ tRNS.green;
         tRNS.red &= mask;
         tRNS.green &= mask;
@@ -3716,7 +3353,7 @@ set_random_tRNS(png_structp pp, png_infop pi, const png_byte colour_type,

      else /* bit_depth == 16 */
      {
-         tRNS.red = random_u16();
+         R16(tRNS.red);
         tRNS.green = (png_uint_16)(tRNS.red * 257);
         tRNS.blue = (png_uint_16)(tRNS.green * 17);
      }
@@ -3724,7 +3361,7 @@ set_random_tRNS(png_structp pp, png_infop pi, const png_byte colour_type,

   else
   {
-      tRNS.gray = random_u16();
+      R16(tRNS.gray);
      tRNS.gray &= mask;
   }

@@ -7676,7 +7313,7 @@ image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
      png_uint_32 ru;
      double total;

-      ru = random_u32();
+      R32(ru);
      data.green_coefficient = total = (ru & 0xffff) / 65535.;
      ru >>= 16;
      data.red_coefficient = (1 - total) * (ru & 0xffff) / 65535.;
@@ -8310,11 +7947,11 @@ image_transform_png_set_background_set(const image_transform *this,
   else
      back.gray = (png_uint_16)data.red;

-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
-#else
-   png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
-#endif
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
+      png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+#  else
+      png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+#  endif

   this->next->set(this->next, that, pp, pi);
 }
@@ -8604,7 +8241,7 @@ image_transform_png_set_filler_set(const image_transform *this,
    * filler.  The 'filler' value has all 32 bits set, but only bit_depth
    * will be used.  At this point we don't know bit_depth.
    */
-   data.filler = random_u32();
+   R32(data.filler);
   data.flags = random_choice();

   png_set_filler(pp, data.filler, data.flags);
@@ -8677,7 +8314,7 @@ image_transform_png_set_add_alpha_set(const image_transform *this,
    * filler.  The 'filler' value has all 32 bits set, but only bit_depth
    * will be used.  At this point we don't know bit_depth.
    */
-   data.filler = random_u32();
+   R32(data.filler);
   data.flags = random_choice();

   png_set_add_alpha(pp, data.filler, data.flags);
--- a/contrib/libtests/timepng.c
+++ b/contrib/libtests/timepng.c
@@ -1,8 +1,8 @@
 /* timepng.c
 *
- * Copyright (c) 2013,2016 John Cunningham Bowler
+ * Copyright (c) 2013 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Last changed in libpng 1.6.1 [March 28, 2013]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -10,17 +10,15 @@
 *
 * Load an arbitrary number of PNG files (from the command line, or, if there
 * are no arguments on the command line, from stdin) then run a time test by
- * reading each file by row or by image (possibly with transforms in the latter
- * case).  The only output is a time as a floating point number of seconds with
- * 9 decimal digits.
+ * reading each file by row.  The test does nothing with the read result and
+ * does no transforms.  The only output is a time as a floating point number of
+ * seconds with 9 decimal digits.
 */
 #define _POSIX_C_SOURCE 199309L /* for clock_gettime */

 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <errno.h>
-#include <limits.h>

 #include <time.h>

@@ -37,73 +35,36 @@
 #  include "../../png.h"
 #endif

-/* The following is to support direct compilation of this file as C++ */
-#ifdef __cplusplus
-#  define voidcast(type, value) static_cast<type>(value)
-#else
-#  define voidcast(type, value) (value)
-#endif /* __cplusplus */
-
-/* 'CLOCK_PROCESS_CPUTIME_ID' is one of the clock timers for clock_gettime.  It
- * need not be supported even when clock_gettime is available.  It returns the
- * 'CPU' time the process has consumed.  'CPU' time is assumed to include time
- * when the CPU is actually blocked by a pending cache fill but not time
- * waiting for page faults.  The attempt is to get a measure of the actual time
- * the implementation takes to read a PNG ignoring the potentially very large IO
- * overhead.
- */
-#if defined (CLOCK_PROCESS_CPUTIME_ID) && defined(PNG_STDIO_SUPPORTED) &&\
-    defined(PNG_EASY_ACCESS_SUPPORTED) &&\
-    (PNG_LIBPNG_VER >= 10700 ? defined(PNG_READ_PNG_SUPPORTED) :\
-     defined (PNG_SEQUENTIAL_READ_SUPPORTED) &&\
-     defined(PNG_INFO_IMAGE_SUPPORTED))
-
-typedef struct
+static int read_png(FILE *fp)
 {
-   FILE *input;
-   FILE *output;
-}  io_data;
-
-static PNG_CALLBACK(void, read_and_copy,
-      (png_structp png_ptr, png_bytep buffer, png_size_t cb))
-{
-   io_data *io = (io_data*)png_get_io_ptr(png_ptr);
-
-   if (fread(buffer, cb, 1, io->input) != 1)
-      png_error(png_ptr, strerror(errno));
-
-   if (fwrite(buffer, cb, 1, io->output) != 1)
-   {
-      perror("temporary file");
-      fprintf(stderr, "temporary file PNG write failed\n");
-      exit(1);
-   }
-}
-
-static void read_by_row(png_structp png_ptr, png_infop info_ptr,
-      FILE *write_ptr, FILE *read_ptr)
-{
-   /* These don't get freed on error, this is fine; the program immediately
-    * exits.
-    */
+   png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+   png_infop info_ptr = NULL;
   png_bytep row = NULL, display = NULL;
-   io_data io_copy;

-   if (write_ptr != NULL)
+   if (png_ptr == NULL)
+      return 0;
+
+   if (setjmp(png_jmpbuf(png_ptr)))
   {
-      /* Set up for a copy to the temporary file: */
-      io_copy.input = read_ptr;
-      io_copy.output = write_ptr;
-      png_set_read_fn(png_ptr, &io_copy, read_and_copy);
+      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+      if (row != NULL) free(row);
+      if (display != NULL) free(display);
+      return 0;
   }

+   png_init_io(png_ptr, fp);
+
+   info_ptr = png_create_info_struct(png_ptr);
+   if (info_ptr == NULL)
+      png_error(png_ptr, "OOM allocating info structure");
+
   png_read_info(png_ptr, info_ptr);

   {
      png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);

-      row = voidcast(png_bytep,malloc(rowbytes));
-      display = voidcast(png_bytep,malloc(rowbytes));
+      row = malloc(rowbytes);
+      display = malloc(rowbytes);

      if (row == NULL || display == NULL)
         png_error(png_ptr, "OOM allocating row buffers");
@@ -120,8 +81,7 @@ static void read_by_row(png_structp png_ptr, png_infop info_ptr,
            png_uint_32 y = height;

            /* NOTE: this trashes the row each time; interlace handling won't
-             * work, but this avoids memory thrashing for speed testing and is
-             * somewhat representative of an application that works row-by-row.
+             * work, but this avoids memory thrashing for speed testing.
             */
            while (y-- > 0)
               png_read_row(png_ptr, row, display);
@@ -131,51 +91,9 @@ static void read_by_row(png_structp png_ptr, png_infop info_ptr,

   /* Make sure to read to the end of the file: */
   png_read_end(png_ptr, info_ptr);
-
-   /* Free this up: */
+   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
   free(row);
   free(display);
-}
-
-static PNG_CALLBACK(void, no_warnings, (png_structp png_ptr,
-         png_const_charp warning))
-{
-   (void)png_ptr;
-   (void)warning;
-}
-
-static int read_png(FILE *fp, png_int_32 transforms, FILE *write_file)
-{
-   png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,
-         no_warnings);
-   png_infop info_ptr = NULL;
-
-   if (png_ptr == NULL)
-      return 0;
-
-   if (setjmp(png_jmpbuf(png_ptr)))
-   {
-      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
-      return 0;
-   }
-
-#  ifdef PNG_BENIGN_ERRORS_SUPPORTED
-      png_set_benign_errors(png_ptr, 1/*allowed*/);
-#  endif
-   png_init_io(png_ptr, fp);
-
-   info_ptr = png_create_info_struct(png_ptr);
-
-   if (info_ptr == NULL)
-      png_error(png_ptr, "OOM allocating info structure");
-
-   if (transforms < 0)
-      read_by_row(png_ptr, info_ptr, write_file, fp);
-
-   else
-      png_read_png(png_ptr, info_ptr, transforms, NULL/*params*/);
-
-   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
   return 1;
 }

@@ -190,7 +108,7 @@ static int mytime(struct timespec *t)
   return 0;
 }

-static int perform_one_test(FILE *fp, int nfiles, png_int_32 transforms)
+static int perform_one_test(FILE *fp, int nfiles)
 {
   int i;
   struct timespec before, after;
@@ -202,7 +120,7 @@ static int perform_one_test(FILE *fp, int nfiles, png_int_32 transforms)
   {
      for (i=0; i<nfiles; ++i)
      {
-         if (read_png(fp, transforms, NULL/*write*/))
+         if (read_png(fp))
         {
            if (ferror(fp))
            {
@@ -266,343 +184,120 @@ static int add_one_file(FILE *fp, char *name)

   if (ip != NULL)
   {
-      /* Read the file using libpng; this detects errors and also deals with
-       * files which contain data beyond the end of the file.
-       */
-      int ok = 0;
-      fpos_t pos;
-
-      if (fgetpos(fp, &pos))
+      int ch;
+      for (;;)
      {
-         /* Fatal error reading the start: */
-         perror("temporary file");
-         fprintf(stderr, "temporary file fgetpos error\n");
-         exit(1);
+         ch = getc(ip);
+         if (ch == EOF) break;
+         putc(ch, fp);
      }

-      if (read_png(ip, -1/*by row*/, fp/*output*/))
+      if (ferror(ip))
      {
-         if (ferror(ip))
-         {
-            perror(name);
-            fprintf(stderr, "%s: read error\n", name);
-         }
-
-         else
-            ok = 1; /* read ok */
+         perror(name);
+         fprintf(stderr, "%s: read error\n", name);
+         return 0;
      }

-      else
-         fprintf(stderr, "%s: file not added\n", name);
-
      (void)fclose(ip);

-      /* An error in the output is fatal; exit immediately: */
      if (ferror(fp))
      {
         perror("temporary file");
         fprintf(stderr, "temporary file write error\n");
-         exit(1);
-      }
-
-      if (ok)
-         return 1;
-
-      /* Did not read the file successfully, simply rewind the temporary
-       * file.  This must happen after the ferror check above to avoid clearing
-       * the error.
-       */
-      if (fsetpos(fp, &pos))
-      {
-         perror("temporary file");
-         fprintf(stderr, "temporary file fsetpos error\n");
-         exit(1);
+         return 0;
      }
   }

   else
   {
-      /* file open error: */
      perror(name);
      fprintf(stderr, "%s: open failed\n", name);
+      return 0;
   }

-   return 0; /* file not added */
-}
-
-static void
-usage(FILE *fp)
-{
-   if (fp != NULL) fclose(fp);
-
-   fprintf(stderr,
-"Usage:\n"
-" timepng --assemble <assembly> {files}\n"
-"  Read the files into <assembly>, output the count.  Options are ignored.\n"
-" timepng --dissemble <assembly> <count> [options]\n"
-"  Time <count> files from <assembly>, additional files may not be given.\n"
-" Otherwise:\n"
-"  Read the files into a temporary file and time the decode\n"
-"Transforms:\n"
-"  --by-image: read by image with png_read_png\n"
-"  --<transform>: implies by-image, use PNG_TRANSFORM_<transform>\n"
-"  Otherwise: read by row using png_read_row (to a single row buffer)\n"
-   /* ISO C90 string length max 509 */);fprintf(stderr,
-"{files}:\n"
-"  PNG files to copy into the assembly and time.  Invalid files are skipped\n"
-"  with appropriate error messages.  If no files are given the list of files\n"
-"  is read from stdin with each file name terminated by a newline\n"
-"Output:\n"
-"  For --assemble the output is the name of the assembly file followed by the\n"
-"  count of the files it contains; the arguments for --dissemble.  Otherwise\n"
-"  the output is the total decode time in seconds.\n");
-
-   exit(99);
+   return 1;
 }

 int main(int argc, char **argv)
 {
   int ok = 0;
-   int err = 0;
-   int nfiles = 0;
-   int transforms = -1; /* by row */
-   const char *assembly = NULL;
-   FILE *fp;
+   FILE *fp = tmpfile();

-   if (argc > 2 && strcmp(argv[1], "--assemble") == 0)
+   if (fp != NULL)
   {
-      /* Just build the test file, argv[2] is the file name. */
-      assembly = argv[2];
-      fp = fopen(assembly, "wb");
-      if (fp == NULL)
+      int err = 0;
+      int nfiles = 0;
+
+      if (argc > 1)
      {
-         perror(assembly);
-         fprintf(stderr, "timepng --assemble %s: could not open for write\n",
-               assembly);
-         usage(NULL);
-      }
+         int i;

-      argv += 2;
-      argc -= 2;
-   }
-
-   else if (argc > 3 && strcmp(argv[1], "--dissemble") == 0)
-   {
-      fp = fopen(argv[2], "rb");
-
-      if (fp == NULL)
-      {
-         perror(argv[2]);
-         fprintf(stderr, "timepng --dissemble %s: could not open for read\n",
-               argv[2]);
-         usage(NULL);
-      }
-
-      nfiles = atoi(argv[3]);
-      if (nfiles <= 0)
-      {
-         fprintf(stderr,
-               "timepng --dissemble <file> <count>: %s is not a count\n",
-               argv[3]);
-         exit(99);
-      }
-#ifdef __COVERITY__
-      else
-      {
-         nfiles &= PNG_UINT_31_MAX;
-      }
-#endif
-
-      argv += 3;
-      argc -= 3;
-   }
-
-   else /* Else use a temporary file */
-   {
-#ifndef __COVERITY__
-      fp = tmpfile();
-#else
-      /* Experimental. Coverity says tmpfile() is insecure because it
-       * generates predictable names.
-       *
-       * It is possible to satisfy Coverity by using mkstemp(); however,
-       * any platform supporting mkstemp() undoubtedly has a secure tmpfile()
-       * implementation as well, and doesn't need the fix.  Note that
-       * the fix won't work on platforms that don't support mkstemp().
-       *
-       * https://www.securecoding.cert.org/confluence/display/c/
-       * FIO21-C.+Do+not+create+temporary+files+in+shared+directories
-       * says that most historic implementations of tmpfile() provide
-       * only a limited number of possible temporary file names
-       * (usually 26) before file names are recycled. That article also
-       * provides a secure solution that unfortunately depends upon mkstemp().
-       */
-      char tmpfile[] = "timepng-XXXXXX";
-      int filedes;
-      umask(0177);
-      filedes = mkstemp(tmpfile);
-      if (filedes < 0)
-        fp = NULL;
-      else
-      {
-        fp = fdopen(filedes,"w+");
-        /* Hide the filename immediately and ensure that the file does
-         * not exist after the program ends
-         */
-        (void) unlink(tmpfile);
-      }
-#endif
-
-      if (fp == NULL)
-      {
-         perror("tmpfile");
-         fprintf(stderr, "timepng: could not open the temporary file\n");
-         exit(1); /* not a user error */
-      }
-   }
-
-   /* Handle the transforms: */
-   while (argc > 1 && argv[1][0] == '-' && argv[1][1] == '-')
-   {
-      const char *opt = *++argv + 2;
-
-      --argc;
-
-      /* Transforms turn on the by-image processing and maybe set some
-       * transforms:
-       */
-      if (transforms == -1)
-         transforms = PNG_TRANSFORM_IDENTITY;
-
-      if (strcmp(opt, "by-image") == 0)
-      {
-         /* handled above */
-      }
-
-#        define OPT(name) else if (strcmp(opt, #name) == 0)\
-         transforms |= PNG_TRANSFORM_ ## name
-
-      OPT(STRIP_16);
-      OPT(STRIP_ALPHA);
-      OPT(PACKING);
-      OPT(PACKSWAP);
-      OPT(EXPAND);
-      OPT(INVERT_MONO);
-      OPT(SHIFT);
-      OPT(BGR);
-      OPT(SWAP_ALPHA);
-      OPT(SWAP_ENDIAN);
-      OPT(INVERT_ALPHA);
-      OPT(STRIP_FILLER);
-      OPT(STRIP_FILLER_BEFORE);
-      OPT(STRIP_FILLER_AFTER);
-      OPT(GRAY_TO_RGB);
-      OPT(EXPAND_16);
-      OPT(SCALE_16);
-
-      else
-      {
-         fprintf(stderr, "timepng %s: unrecognized transform\n", opt);
-         usage(fp);
-      }
-   }
-
-   /* Handle the files: */
-   if (argc > 1 && nfiles > 0)
-      usage(fp); /* Additional files not valid with --dissemble */
-
-   else if (argc > 1)
-   {
-      int i;
-
-      for (i=1; i<argc; ++i)
-      {
-         if (nfiles == INT_MAX)
+         for (i=1; i<argc; ++i)
         {
-            fprintf(stderr, "%s: skipped, too many files\n", argv[i]);
-            break;
-         }
+            if (add_one_file(fp, argv[i]))
+               ++nfiles;

-         else if (add_one_file(fp, argv[i]))
-            ++nfiles;
-      }
-   }
-
-   else if (nfiles == 0) /* Read from stdin withoout --dissemble */
-   {
-      char filename[FILENAME_MAX+1];
-
-      while (fgets(filename, FILENAME_MAX+1, stdin))
-      {
-         size_t len = strlen(filename);
-
-         if (filename[len-1] == '\n')
-         {
-            filename[len-1] = 0;
-            if (nfiles == INT_MAX)
+            else
            {
-               fprintf(stderr, "%s: skipped, too many files\n", filename);
+               err = 1;
               break;
            }
-
-            else if (add_one_file(fp, filename))
-               ++nfiles;
-         }
-
-         else
-         {
-            fprintf(stderr, "timepng: file name too long: ...%s\n",
-               filename+len-32);
-            err = 1;
-            break;
         }
      }

-      if (ferror(stdin))
+      else
      {
-         fprintf(stderr, "timepng: stdin: read error\n");
-         err = 1;
-      }
-   }
+         char filename[FILENAME_MAX+1];

-   /* Perform the test, or produce the --assemble output: */
-   if (!err)
-   {
-      if (nfiles > 0)
-      {
-         if (assembly != NULL)
+         while (fgets(filename, FILENAME_MAX+1, stdin))
         {
-            if (fflush(fp) && !ferror(fp) && fclose(fp))
+            size_t len = strlen(filename);
+
+            if (filename[len-1] == '\n')
            {
-               perror(assembly);
-               fprintf(stderr, "%s: close failed\n", assembly);
+               filename[len-1] = 0;
+               if (add_one_file(fp, filename))
+                  ++nfiles;
+
+               else
+               {
+                  err = 1;
+                  break;
+               }
            }

            else
            {
-               printf("%s %d\n", assembly, nfiles);
-               fflush(stdout);
-               ok = !ferror(stdout);
+               fprintf(stderr, "timepng: truncated file name ...%s\n",
+                  filename+len-32);
+               err = 1;
+               break;
            }
         }

-         else
+         if (ferror(stdin))
         {
-            ok = perform_one_test(fp, nfiles, transforms);
-            (void)fclose(fp);
+            fprintf(stderr, "timepng: stdin: read error\n");
+            err = 1;
         }
      }

-      else
-         usage(fp);
+      if (!err)
+      {
+         if (nfiles > 0)
+            ok = perform_one_test(fp, nfiles);
+
+         else
+            fprintf(stderr, "usage: timepng {files} or ls files | timepng\n");
+      }
+
+      (void)fclose(fp);
   }

   else
-      (void)fclose(fp);
+      fprintf(stderr, "timepng: could not open temporary file\n");

   /* Exit code 0 on success. */
   return ok == 0;
 }
-#else /* !sufficient support */
-int main(void) { return 77; }
-#endif /* !sufficient support */
--- a/contrib/mips-msa/README
+++ b/contrib/mips-msa/README
@@ -1,83 +0,0 @@
-OPERATING SYSTEM SPECIFIC MIPS MSA DETECTION
--------------------------------------------
-
-Detection of the ability to execute MIPS MSA on an MIPS processor requires
-operating system support.  (The information is not available in user mode.)
-
-HOW TO USE THIS
---------------
-
-This directory contains C code fragments that can be included in mips/mips_init.c
-by setting the macro PNG_MIPS_MSA_FILE to the file name in "" or <> at build
-time.  This setting is not recorded in pnglibconf.h and can be changed simply by
-rebuilding mips/msa_init.o with the required macro definition.
-
-For any of this code to be used the MIPS MSA code must be enabled and run time
-checks must be supported.  I.e.:
-
-#if PNG_MIPS_MSA_OPT > 0
-#ifdef PNG_MIPS_MSA_CHECK_SUPPORTED
-
-This is done in a 'configure' build by passing configure the argument:
-
-   --enable-mips-msa=check
-
-Apart from the basic Linux implementation in contrib/mips-msa/linux.c this code
-is unsupported.  That means that it is not even compiled on a regular basis and
-may be broken in any given minor release.
-
-FILE FORMAT
-----------
-
-Each file documents its testing status as of the last time it was tested (which
-may have been a long time ago):
-
-STATUS: one of:
-   SUPPORTED: This indicates that the file is included in the regularly
-         performed test builds and bugs are fixed when discovered.
-   COMPILED: This indicates that the code did compile at least once.  See the
-         more detailed description for the extent to which the result was
-         successful.
-   TESTED: This means the code was fully compiled into the libpng test programs
-         and these were run at least once.
-
-BUG REPORTS: an email address to which to send reports of problems
-
-The file is a fragment of C code. It should not define any 'extern' symbols;
-everything should be static.  It must define the function:
-
-static int png_have_msa(png_structp png_ptr);
-
-That function must return 1 if MIPS MSA instructions are supported, 0 if not.
-It must not execute png_error unless it detects a bug.  A png_error will prevent
-the reading of the PNG and in the future, writing too.
-
-BUG REPORTS
-----------
-
-If you mail a bug report for any file that is not SUPPORTED there may only be
-limited response.  Consider fixing it and sending a patch to fix the problem -
-this is more likely to result in action.
-
-CONTRIBUTIONS
-------------
-
-You may send contributions of new implementations to
-png-mng-implement@sourceforge.net.  Please write code in strict C90 C where
-possible.  Obviously OS dependencies are to be expected.  If you submit code you
-must have the authors permission and it must have a license that is acceptable
-to the current maintainer; in particular that license must permit modification
-and redistribution.
-
-Please try to make the contribution a single file and give the file a clear and
-unambiguous name that identifies the target OS.  If multiple files really are
-required put them all in a sub-directory.
-
-You must also be prepared to handle bug reports from users of the code, either
-by joining the png-mng-implement mailing list or by providing an email for the
-"BUG REPORTS" entry or both.  Please make sure that the header of the file
-contains the STATUS and BUG REPORTS fields as above.
-
-Please list the OS requirements as precisely as possible.  Ideally you should
-also list the environment in which the code has been tested and certainly list
-any environments where you suspect it might not work.
--- a/contrib/mips-msa/linux.c
+++ b/contrib/mips-msa/linux.c
@@ -1,64 +0,0 @@
-/* contrib/mips-msa/linux.c
- *
- * Copyright (c) 2016 Glenn Randers-Pehrson
- * Written by Mandar Sahastrabuddhe, 2016.
- * Last changed in libpng 1.6.25beta03 [August 29, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- *
- * SEE contrib/mips-msa/README before reporting bugs
- *
- * STATUS: SUPPORTED
- * BUG REPORTS: png-mng-implement@sourceforge.net
- *
- * png_have_msa implemented for Linux by reading the widely available
- * pseudo-file /proc/cpuinfo.
- *
- * This code is strict ANSI-C and is probably moderately portable; it does
- * however use <stdio.h> and it assumes that /proc/cpuinfo is never localized.
- */
-
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-
-static int
-png_have_msa(png_structp png_ptr)
-{
-   FILE *f = fopen("/proc/cpuinfo", "rb");
-
-   char *string = "msa";
-   char word[10];
-
-   if (f != NULL)
-   {
-      while(!feof(f))
-      {
-         int ch = fgetc(f);
-         static int i = 0;
-
-         while(!(ch <= 32))
-         {
-            word[i++] = ch;
-            ch = fgetc(f);
-         }
-
-         int val = strcmp(string, word);
-
-         if (val == 0)
-            return 1;
-
-         i = 0;
-         memset(word, 0, 10);
-      }
-
-      fclose(f);
-   }
-#ifdef PNG_WARNINGS_SUPPORTED
-   else
-      png_warning(png_ptr, "/proc/cpuinfo open failed");
-#endif
-   return 0;
-}
--- a/contrib/tools/chkfmt
+++ b/contrib/tools/chkfmt
@@ -1,11 +1,4 @@
 #!/bin/sh
-
-# chkfmt
-#
-# COPYRIGHT: Written by John Cunningham Bowler, 2010.
-# To the extent possible under law, the author has waived all copyright and
-# related or neighboring rights to this work.  This work is published from:
-# United States.
 #
 # Check the format of the source files in the current directory - checks for a
 # line length of 80 characters max and no tab characters.
--- a/contrib/tools/pngcp.c
+++ b/contrib/tools/pngcp.c
--- a/contrib/tools/reindent
+++ b/contrib/tools/reindent
@@ -1,25 +0,0 @@
-#!/bin/sh
-
-# reindent a libpng C source
-
-# COPYRIGHT: Written by Glenn Randers-Pehrson, 2016.
-# To the extent possible under law, the author has waived all copyright and
-# related or neighboring rights to this work.  This work is published from:
-# United States.
-
-# Usage:
-# reindent inputtabsize outputtabsize inputcontinuestring outputcontinuestring
-#
-# Assumes that continued lines begin with indentation plus one space, and
-# that continued comments begin with indentation plus " *".
-#
-# eg, to change libpng coding style from 3-space indentation with 4-space
-# continuations to 4-space indentation with 2-space continuations:
-#
-#  reindent 3 4 "\t " "  " < example.c > example.c_4_2
-# and to restore the file back to libpng coding style
-#  reindent 4 3 "  " "    " < example.c_4_2 > example.c_3_4
-
-unexpand --first-only --t $1 | \
-   sed -e "/^	*$3[^\*]/{s/$3/$4/}" | \
-   expand -t $2
--- a/example.c
+++ b/example.c
@@ -2,8 +2,8 @@
 #if 0 /* in case someone actually tries to compile this */

 /* example.c - an example of using libpng
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Maintained 1998-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Maintained 1998-2014 Glenn Randers-Pehrson
 * Maintained 1996, 1997 Andreas Dilger)
 * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 * To the extent possible under law, the authors have waived
@@ -97,7 +97,7 @@ int main(int argc, const char **argv)
          */
         if (buffer != NULL &&
            png_image_finish_read(&image, NULL/*background*/, buffer,
-                0/*row_stride*/, NULL/*colormap*/) != 0)
+               0/*row_stride*/, NULL/*colormap*/) != 0)
         {
            /* Now write the image out to the second argument.  In the write
             * call 'convert_to_8bit' allows 16-bit data to be squashed down to
@@ -105,7 +105,7 @@ int main(int argc, const char **argv)
             * to the 8-bit format.
             */
            if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
-                buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
+               buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
            {
               /* The image has been written successfully. */
               exit(0);
@@ -295,7 +295,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * was compiled with a compatible version of the library.  REQUIRED
    */
   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
-       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+      png_voidp user_error_ptr, user_error_fn, user_warning_fn);

   if (png_ptr == NULL)
   {
@@ -375,7 +375,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * low byte.
    */
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-   png_set_scale_16(png_ptr);
+    png_set_scale_16(png_ptr);
 #else
   png_set_strip_16(png_ptr);
 #endif
@@ -419,10 +419,10 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */

   if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
      png_set_background(png_ptr, image_background,
-          PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+                         PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
   else
      png_set_background(png_ptr, &my_background,
-          PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
+                         PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);

   /* Some suggestions as to how to get a screen gamma value
    *
@@ -481,7 +481,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
         png_color std_color_cube[MAX_SCREEN_COLORS];

         png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
-             MAX_SCREEN_COLORS, NULL, 0);
+            MAX_SCREEN_COLORS, NULL, 0);
      }
      /* This reduces the image to the palette supplied in the file */
      else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
@@ -491,7 +491,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
         png_get_hIST(png_ptr, info_ptr, &histogram);

         png_set_quantize(png_ptr, palette, num_palette,
-             max_screen_colors, histogram, 0);
+                        max_screen_colors, histogram, 0);
      }
   }
 #endif /* READ_QUANTIZE */
@@ -530,7 +530,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * see the png_read_row() method below:
    */
   number_passes = png_set_interlace_handling(png_ptr);
-#else /* !READ_INTERLACING */
+#else
   number_passes = 1;
 #endif /* READ_INTERLACING */

@@ -552,7 +552,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */

   for (row = 0; row < height; row++)
      row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
-          info_ptr));
+         info_ptr));

   /* Now it's time to read the image.  One of these methods is REQUIRED */
 #ifdef entire /* Read the entire image in one go */
@@ -574,10 +574,10 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
      {
 #ifdef sparkle /* Read the image using the "sparkle" effect. */
         png_read_rows(png_ptr, &row_pointers[y], NULL,
-             number_of_rows);
+            number_of_rows);
 #else no_sparkle /* Read the image using the "rectangle" effect */
         png_read_rows(png_ptr, NULL, &row_pointers[y],
-             number_of_rows);
+            number_of_rows);
 #endif no_sparkle /* Use only one of these two methods */
      }

@@ -614,7 +614,7 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    * linked libraries.
    */
   *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
-        png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+       png_voidp user_error_ptr, user_error_fn, user_warning_fn);

   if (*png_ptr == NULL)
   {
@@ -649,14 +649,14 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    * the function png_get_progressive_ptr(png_ptr).
    */
   png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
-       info_callback, row_callback, end_callback);
+      info_callback, row_callback, end_callback);

   return (OK);
 }

 int
 process_data(png_structp *png_ptr, png_infop *info_ptr,
-    png_bytep buffer, png_uint_32 length)
+   png_bytep buffer, png_uint_32 length)
 {
   if (setjmp(png_jmpbuf((*png_ptr))))
   {
@@ -691,7 +691,7 @@ info_callback(png_structp png_ptr, png_infop info)
 }

 row_callback(png_structp png_ptr, png_bytep new_row,
-    png_uint_32 row_num, int pass)
+   png_uint_32 row_num, int pass)
 {
   /*
    * This function is called for every row in the image.  If the
@@ -780,7 +780,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    * in case we are using dynamically linked libraries.  REQUIRED.
    */
   png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
-       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+      png_voidp user_error_ptr, user_error_fn, user_warning_fn);

   if (png_ptr == NULL)
   {
@@ -819,7 +819,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    * png_init_io() here you would call
    */
   png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
-       user_IO_flush_function);
+      user_IO_flush_function);
   /* where user_io_ptr is a structure you want available to the callbacks */
 #endif no_streams /* Only use one initialization method */

@@ -842,7 +842,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
    */
   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
-       PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+      PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

   /* Set the palette if there is one.  REQUIRED for indexed-color images */
   palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
@@ -988,11 +988,11 @@ void write_png(char *file_name /* , ... other image information ... */)
   png_bytep row_pointers[height];

   if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
-      png_error (png_ptr, "Image is too tall to process in memory");
+     png_error (png_ptr, "Image is too tall to process in memory");

   /* Set up pointers into your "image" byte array */
   for (k = 0; k < height; k++)
-      row_pointers[k] = image + k*width*bytes_per_pixel;
+     row_pointers[k] = image + k*width*bytes_per_pixel;

   /* One of the following output methods is REQUIRED */

--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.25 - September 1, 2016
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.25 - September 1, 2016
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2016 Glenn Randers-Pehrson

@@ -559,7 +559,7 @@ non-interlaced case the row that was just handled is simply one less than the
 passed in row number, and pass will always be 0.  For the interlaced case the
 same applies unless the row value is 0, in which case the row just handled was
 the last one from one of the preceding passes.  Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass-1'; if you really
+pass you cannot be sure that the preceding pass is just 'pass-1', if you really
 need to know what the last pass is record (row,pass) from the callback and use
 the last recorded value each time.

@@ -2230,8 +2230,7 @@ is exactly the same.  If you are planning on displaying the image
 after each pass, the "rectangle" effect is generally considered the
 better looking one.

-If you only want the "sparkle" effect, just call png_read_row() or
-png_read_rows() as
+If you only want the "sparkle" effect, just call png_read_rows() as
 normal, with the third parameter NULL.  Make sure you make pass over
 the image number_of_passes times, and you don't change the data in the
 rows between calls.  You can change the locations of the data, just
@@ -2240,8 +2239,6 @@ pass, and assumes the data from previous passes is still valid.

    png_read_rows(png_ptr, row_pointers, NULL,
        number_of_rows);
-    or
-    png_read_row(png_ptr, row_pointers, NULL);

 If you only want the first effect (the rectangles), do the same as
 before except pass the row buffer in the third parameter, and leave
@@ -2249,8 +2246,6 @@ the second parameter NULL.

    png_read_rows(png_ptr, NULL, row_pointers,
        number_of_rows);
-    or
-    png_read_row(png_ptr, NULL, row_pointers);

 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
@@ -2847,7 +2842,7 @@ filter types.
       PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
       PNG_FILTER_AVG   | PNG_FILTER_VALUE_AVG  |
       PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
-       PNG_ALL_FILTERS  | PNG_FAST_FILTERS);
+       PNG_ALL_FILTERS);

 If an application wants to start and stop using particular filters during
 compression, it should start out with all of the filters (to ensure that
@@ -4108,13 +4103,6 @@ be written:

      Write the image to the named file.

-   int png_image_write_to_memory (png_imagep image, void *memory,
-      png_alloc_size_t * PNG_RESTRICT memory_bytes,
-      int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
-      const void *colormap));
-
-      Write the image to memory.
-
   int png_image_write_to_stdio(png_imagep image, FILE *file,
      int convert_to_8_bit, const void *buffer,
      png_int_32 row_stride, const void *colormap)
@@ -4392,9 +4380,8 @@ for any images with bit depths less than 8 bits/pixel.
 The 'method' parameter sets the main filtering method, which is
 currently only '0' in the PNG 1.2 specification.  The 'filters'
 parameter sets which filter(s), if any, should be used for each
-scanline.  Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
-or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
-just the fast-decoding subset of filters, respectively.
+scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.

 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
@@ -4408,19 +4395,12 @@ means the first row must always be adaptively filtered, because libpng
 currently does not allocate the filter buffers until png_write_row()
 is called for the first time.)

-    filters = PNG_NO_FILTERS;
-    filters = PNG_ALL_FILTERS;
-    filters = PNG_FAST_FILTERS;
-
-    or
-
-    filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
+    filters = PNG_FILTER_NONE | PNG_FILTER_SUB
              PNG_FILTER_UP | PNG_FILTER_AVG |
-              PNG_FILTER_PAETH;
+              PNG_FILTER_PAETH | PNG_ALL_FILTERS;

    png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
       filters);
-
              The second parameter can also be
              PNG_INTRAPIXEL_DIFFERENCING if you are
              writing a PNG to be embedded in a MNG
@@ -4795,8 +4775,7 @@ There are no substantial API changes between the non-deprecated parts of
 the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
 members of the main libpng control structures, png_struct and png_info,
 deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
-header files were created.
+libpng 1.5.

 We no longer include zlib.h in png.h.  The include statement has been moved
 to pngstruct.h, where it is not accessible by applications. Applications that
@@ -5036,7 +5015,6 @@ includes the following:
     png_image_free()
   write functions
     png_image_write_to_file()
-     png_image_write_to_memory()
     png_image_write_to_stdio()

 Starting with libpng-1.6.0, you can configure libpng to prefix all exported
@@ -5350,7 +5328,7 @@ Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.25 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.21 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.

 Libpng only has two year fields.  One is a 2-byte unsigned integer
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "September 1, 2016"
+.TH LIBPNG 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.25
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -229,8 +229,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.25

 \fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP

-\fBint png_image_write_to_memory (png_imagep \fP\fIimage\fP\fB, void \fP\fI*memory\fP\fB, png_alloc_size_t * PNG_RESTRICT \fP\fImemory_bytes\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, const void \fI*colormap)\fP\fB);\fP
-
 \fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP

 \fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
@@ -510,7 +508,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.25 - September 1, 2016
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -521,7 +519,7 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.25 - September 1, 2016
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2016 Glenn Randers-Pehrson

@@ -1069,7 +1067,7 @@ non-interlaced case the row that was just handled is simply one less than the
 passed in row number, and pass will always be 0.  For the interlaced case the
 same applies unless the row value is 0, in which case the row just handled was
 the last one from one of the preceding passes.  Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass\-1'; if you really
+pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
 need to know what the last pass is record (row,pass) from the callback and use
 the last recorded value each time.

@@ -2740,8 +2738,7 @@ is exactly the same.  If you are planning on displaying the image
 after each pass, the "rectangle" effect is generally considered the
 better looking one.

-If you only want the "sparkle" effect, just call png_read_row() or
-png_read_rows() as
+If you only want the "sparkle" effect, just call png_read_rows() as
 normal, with the third parameter NULL.  Make sure you make pass over
 the image number_of_passes times, and you don't change the data in the
 rows between calls.  You can change the locations of the data, just
@@ -2750,8 +2747,6 @@ pass, and assumes the data from previous passes is still valid.

    png_read_rows(png_ptr, row_pointers, NULL,
        number_of_rows);
-    or
-    png_read_row(png_ptr, row_pointers, NULL);

 If you only want the first effect (the rectangles), do the same as
 before except pass the row buffer in the third parameter, and leave
@@ -2759,8 +2754,6 @@ the second parameter NULL.

    png_read_rows(png_ptr, NULL, row_pointers,
        number_of_rows);
-    or
-    png_read_row(png_ptr, NULL, row_pointers);

 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
@@ -3357,7 +3350,7 @@ filter types.
       PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
       PNG_FILTER_AVG   | PNG_FILTER_VALUE_AVG  |
       PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
-       PNG_ALL_FILTERS  | PNG_FAST_FILTERS);
+       PNG_ALL_FILTERS);

 If an application wants to start and stop using particular filters during
 compression, it should start out with all of the filters (to ensure that
@@ -4618,13 +4611,6 @@ be written:

      Write the image to the named file.

-   int png_image_write_to_memory (png_imagep image, void *memory,
-      png_alloc_size_t * PNG_RESTRICT memory_bytes,
-      int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
-      const void *colormap));
-
-      Write the image to memory.
-
   int png_image_write_to_stdio(png_imagep image, FILE *file,
      int convert_to_8_bit, const void *buffer,
      png_int_32 row_stride, const void *colormap)
@@ -4902,9 +4888,8 @@ for any images with bit depths less than 8 bits/pixel.
 The 'method' parameter sets the main filtering method, which is
 currently only '0' in the PNG 1.2 specification.  The 'filters'
 parameter sets which filter(s), if any, should be used for each
-scanline.  Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
-or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
-just the fast-decoding subset of filters, respectively.
+scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.

 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
@@ -4918,19 +4903,12 @@ means the first row must always be adaptively filtered, because libpng
 currently does not allocate the filter buffers until png_write_row()
 is called for the first time.)

-    filters = PNG_NO_FILTERS;
-    filters = PNG_ALL_FILTERS;
-    filters = PNG_FAST_FILTERS;
-
-    or
-
-    filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
+    filters = PNG_FILTER_NONE | PNG_FILTER_SUB
              PNG_FILTER_UP | PNG_FILTER_AVG |
-              PNG_FILTER_PAETH;
+              PNG_FILTER_PAETH | PNG_ALL_FILTERS;

    png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
       filters);
-
              The second parameter can also be
              PNG_INTRAPIXEL_DIFFERENCING if you are
              writing a PNG to be embedded in a MNG
@@ -5305,8 +5283,7 @@ There are no substantial API changes between the non-deprecated parts of
 the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
 members of the main libpng control structures, png_struct and png_info,
 deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
-header files were created.
+libpng 1.5.

 We no longer include zlib.h in png.h.  The include statement has been moved
 to pngstruct.h, where it is not accessible by applications. Applications that
@@ -5546,7 +5523,6 @@ includes the following:
     png_image_free()
   write functions
     png_image_write_to_file()
-     png_image_write_to_memory()
     png_image_write_to_stdio()

 Starting with libpng-1.6.0, you can configure libpng to prefix all exported
@@ -5860,7 +5836,7 @@ Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.25 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.21 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.

 Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -5958,11 +5934,11 @@ the first widely used release:
 ...
 1.0.19                  10    10019  10.so.0.19[.0]
 ...
- 1.2.56                  13    10256  12.so.0.56[.0]
+ 1.2.53                  13    10253  12.so.0.53[.0]
 ...
- 1.5.27                  15    10527  15.so.15.27[.0]
+ 1.5.23                  15    10523  15.so.15.23[.0]
 ...
- 1.6.25                  16    10625  16.so.16.25[.0]
+ 1.6.21                  16    10621  16.so.16.21[.0]

 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6018,7 +5994,7 @@ possible without all of you.

 Thanks to Frank J. T. Wojcik for helping with the documentation.

-Libpng version 1.6.25 - September 1, 2016:
+Libpng version 1.6.21 - January 15, 2016:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).

@@ -6043,7 +6019,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -6065,10 +6041,6 @@ and with the following additions to the disclaimer:
   risk of satisfactory quality, performance, accuracy, and effort is with
   the user.

-Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
-are released under other open source licenses.
-
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
@@ -6092,9 +6064,6 @@ Contributing Authors:
   Greg Roelofs
   Tom Tanner

-Some files in the "scripts" directory have other copyright owners
-but are released under this license.
-
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

@@ -6135,29 +6104,6 @@ appreciated.

 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

-TRADEMARK:
-
-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction.  However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
-
-OSI CERTIFICATION:
-
-Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
-a certification mark of the Open Source Initiative. OSI has not addressed
-the additional disclaimers inserted at version 1.0.7.
-
-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
 A "png_get_copyright" function is available, for convenient use in "about"
 boxes and the like:

@@ -6166,9 +6112,13 @@ boxes and the like:
 Also, the PNG logo (in PNG format, of course) is supplied in the
 files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).

+Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
+a certification mark of the Open Source Initiative. OSI has not addressed
+the additional disclaimers inserted at version 1.0.7.
+
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-September 1, 2016
+January 15, 2016

 .\" end of man page

--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "September 1, 2016"
+.TH LIBPNGPF 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.25
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
--- a/mips/filter_msa_intrinsics.c
+++ b/mips/filter_msa_intrinsics.c
@@ -1,807 +0,0 @@
-
-/* filter_msa_intrinsics.c - MSA optimised filter functions
- *
- * Copyright (c) 2016 Glenn Randers-Pehrson
- * Written by Mandar Sahastrabuddhe, August 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-#include <stdio.h>
-#include <stdint.h>
-#include "../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-/* This code requires -mfpu=msa on the command line: */
-#if PNG_MIPS_MSA_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
-
-#include <msa.h>
-
-/* libpng row pointers are not necessarily aligned to any particular boundary,
- * however this code will only work with appropriate alignment. mips/mips_init.c
- * checks for this (and will not compile unless it is done). This code uses
- * variants of png_aligncast to avoid compiler warnings.
- */
-#define png_ptr(type,pointer) png_aligncast(type *,pointer)
-#define png_ptrc(type,pointer) png_aligncastconst(const type *,pointer)
-
-/* The following relies on a variable 'temp_pointer' being declared with type
- * 'type'.  This is written this way just to hide the GCC strict aliasing
- * warning; note that the code is safe because there never is an alias between
- * the input and output pointers.
- */
-#define png_ldr(type,pointer)\
-   (temp_pointer = png_ptr(type,pointer), *temp_pointer)
-
-#if PNG_MIPS_MSA_OPT > 0
-
-#ifdef CLANG_BUILD
-   #define MSA_SRLI_B(a, b)   __msa_srli_b((v16i8) a, b)
-
-   #define LW(psrc)                              \
-   ( {                                           \
-       uint8_t *psrc_lw_m = (uint8_t *) (psrc);  \
-       uint32_t val_m;                           \
-                                                 \
-       asm volatile (                            \
-           "lw  %[val_m],  %[psrc_lw_m]  \n\t"   \
-                                                 \
-           : [val_m] "=r" (val_m)                \
-           : [psrc_lw_m] "m" (*psrc_lw_m)        \
-       );                                        \
-                                                 \
-       val_m;                                    \
-   } )
-
-   #define SH(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sh_m = (uint8_t *) (pdst);  \
-       uint16_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "sh  %[val_m],  %[pdst_sh_m]  \n\t"   \
-                                                 \
-           : [pdst_sh_m] "=m" (*pdst_sh_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-   #define SW(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sw_m = (uint8_t *) (pdst);  \
-       uint32_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "sw  %[val_m],  %[pdst_sw_m]  \n\t"   \
-                                                 \
-           : [pdst_sw_m] "=m" (*pdst_sw_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-       #if (__mips == 64)
-        #define SD(val, pdst)                         \
-        {                                             \
-            uint8_t *pdst_sd_m = (uint8_t *) (pdst);  \
-            uint64_t val_m = (val);                   \
-                                                      \
-            asm volatile (                            \
-                "sd  %[val_m],  %[pdst_sd_m]  \n\t"   \
-                                                      \
-                : [pdst_sd_m] "=m" (*pdst_sd_m)       \
-                : [val_m] "r" (val_m)                 \
-            );                                        \
-        }
-    #else
-        #define SD(val, pdst)                                          \
-        {                                                              \
-            uint8_t *pdst_sd_m = (uint8_t *) (pdst);                   \
-            uint32_t val0_m, val1_m;                                   \
-                                                                       \
-            val0_m = (uint32_t) ((val) & 0x00000000FFFFFFFF);          \
-            val1_m = (uint32_t) (((val) >> 32) & 0x00000000FFFFFFFF);  \
-                                                                       \
-            SW(val0_m, pdst_sd_m);                                     \
-            SW(val1_m, pdst_sd_m + 4);                                 \
-        }
-    #endif
-#else
-   #define MSA_SRLI_B(a, b)   (a >> b)
-
-#if (__mips_isa_rev >= 6)
-   #define LW(psrc)                              \
-   ( {                                           \
-       uint8_t *psrc_lw_m = (uint8_t *) (psrc);  \
-       uint32_t val_m;                           \
-                                                 \
-       asm volatile (                            \
-           "lw  %[val_m],  %[psrc_lw_m]  \n\t"   \
-                                                 \
-           : [val_m] "=r" (val_m)                \
-           : [psrc_lw_m] "m" (*psrc_lw_m)        \
-       );                                        \
-                                                 \
-       val_m;                                    \
-   } )
-
-   #define SH(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sh_m = (uint8_t *) (pdst);  \
-       uint16_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "sh  %[val_m],  %[pdst_sh_m]  \n\t"   \
-                                                 \
-           : [pdst_sh_m] "=m" (*pdst_sh_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-   #define SW(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sw_m = (uint8_t *) (pdst);  \
-       uint32_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "sw  %[val_m],  %[pdst_sw_m]  \n\t"   \
-                                                 \
-           : [pdst_sw_m] "=m" (*pdst_sw_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-   #if (__mips == 64)
-        #define SD(val, pdst)                         \
-        {                                             \
-            uint8_t *pdst_sd_m = (uint8_t *) (pdst);  \
-            uint64_t val_m = (val);                   \
-                                                      \
-            asm volatile (                            \
-                "sd  %[val_m],  %[pdst_sd_m]  \n\t"   \
-                                                      \
-                : [pdst_sd_m] "=m" (*pdst_sd_m)       \
-                : [val_m] "r" (val_m)                 \
-            );                                        \
-        }
-    #else
-        #define SD(val, pdst)                                          \
-        {                                                              \
-            uint8_t *pdst_sd_m = (uint8_t *) (pdst);                   \
-            uint32_t val0_m, val1_m;                                   \
-                                                                       \
-            val0_m = (uint32_t) ((val) & 0x00000000FFFFFFFF);          \
-            val1_m = (uint32_t) (((val) >> 32) & 0x00000000FFFFFFFF);  \
-                                                                       \
-            SW(val0_m, pdst_sd_m);                                     \
-            SW(val1_m, pdst_sd_m + 4);                                 \
-        }
-    #endif
-#else  // !(__mips_isa_rev >= 6)
-   #define LW(psrc)                              \
-   ( {                                           \
-       uint8_t *psrc_lw_m = (uint8_t *) (psrc);  \
-       uint32_t val_m;                           \
-                                                 \
-       asm volatile (                            \
-           "ulw  %[val_m],  %[psrc_lw_m]  \n\t"  \
-                                                 \
-           : [val_m] "=r" (val_m)                \
-           : [psrc_lw_m] "m" (*psrc_lw_m)        \
-       );                                        \
-                                                 \
-       val_m;                                    \
-   } )
-
-   #define SH(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sh_m = (uint8_t *) (pdst);  \
-       uint16_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "ush  %[val_m],  %[pdst_sh_m]  \n\t"  \
-                                                 \
-           : [pdst_sh_m] "=m" (*pdst_sh_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-   #define SW(val, pdst)                         \
-   {                                             \
-       uint8_t *pdst_sw_m = (uint8_t *) (pdst);  \
-       uint32_t val_m = (val);                   \
-                                                 \
-       asm volatile (                            \
-           "usw  %[val_m],  %[pdst_sw_m]  \n\t"  \
-                                                 \
-           : [pdst_sw_m] "=m" (*pdst_sw_m)       \
-           : [val_m] "r" (val_m)                 \
-       );                                        \
-   }
-
-   #define SD(val, pdst)                                          \
-    {                                                              \
-        uint8_t *pdst_sd_m = (uint8_t *) (pdst);                   \
-        uint32_t val0_m, val1_m;                                   \
-                                                                   \
-        val0_m = (uint32_t) ((val) & 0x00000000FFFFFFFF);          \
-        val1_m = (uint32_t) (((val) >> 32) & 0x00000000FFFFFFFF);  \
-                                                                   \
-        SW(val0_m, pdst_sd_m);                                     \
-        SW(val1_m, pdst_sd_m + 4);                                 \
-    }
-
-    #define SW_ZERO(pdst)                      \
-    {                                          \
-        uint8_t *pdst_m = (uint8_t *) (pdst);  \
-                                               \
-        asm volatile (                         \
-            "usw  $0,  %[pdst_m]  \n\t"        \
-                                               \
-            : [pdst_m] "=m" (*pdst_m)          \
-            :                                  \
-        );                                     \
-    }
-#endif  // (__mips_isa_rev >= 6)
-#endif
-
-#define LD_B(RTYPE, psrc) *((RTYPE *) (psrc))
-#define LD_UB(...) LD_B(v16u8, __VA_ARGS__)
-#define LD_B2(RTYPE, psrc, stride, out0, out1)  \
-{                                               \
-    out0 = LD_B(RTYPE, (psrc));                 \
-    out1 = LD_B(RTYPE, (psrc) + stride);        \
-}
-#define LD_UB2(...) LD_B2(v16u8, __VA_ARGS__)
-#define LD_B4(RTYPE, psrc, stride, out0, out1, out2, out3)   \
-{                                                            \
-    LD_B2(RTYPE, (psrc), stride, out0, out1);                \
-    LD_B2(RTYPE, (psrc) + 2 * stride , stride, out2, out3);  \
-}
-#define LD_UB4(...) LD_B4(v16u8, __VA_ARGS__)
-
-#define ST_B(RTYPE, in, pdst) *((RTYPE *) (pdst)) = (in)
-#define ST_UB(...) ST_B(v16u8, __VA_ARGS__)
-#define ST_B2(RTYPE, in0, in1, pdst, stride)  \
-{                                             \
-    ST_B(RTYPE, in0, (pdst));                 \
-    ST_B(RTYPE, in1, (pdst) + stride);        \
-}
-#define ST_UB2(...) ST_B2(v16u8, __VA_ARGS__)
-#define ST_B4(RTYPE, in0, in1, in2, in3, pdst, stride)    \
-{                                                         \
-    ST_B2(RTYPE, in0, in1, (pdst), stride);               \
-    ST_B2(RTYPE, in2, in3, (pdst) + 2 * stride, stride);  \
-}
-#define ST_UB4(...) ST_B4(v16u8, __VA_ARGS__)
-
-#define ADD2(in0, in1, in2, in3, out0, out1)  \
-{                                             \
-    out0 = in0 + in1;                         \
-    out1 = in2 + in3;                         \
-}
-#define ADD3(in0, in1, in2, in3, in4, in5,  \
-             out0, out1, out2)              \
-{                                           \
-    ADD2(in0, in1, in2, in3, out0, out1);   \
-    out2 = in4 + in5;                       \
-}
-#define ADD4(in0, in1, in2, in3, in4, in5, in6, in7,  \
-             out0, out1, out2, out3)                  \
-{                                                     \
-    ADD2(in0, in1, in2, in3, out0, out1);             \
-    ADD2(in4, in5, in6, in7, out2, out3);             \
-}
-
-#define ILVR_B2(RTYPE, in0, in1, in2, in3, out0, out1)      \
-{                                                           \
-    out0 = (RTYPE) __msa_ilvr_b((v16i8) in0, (v16i8) in1);  \
-    out1 = (RTYPE) __msa_ilvr_b((v16i8) in2, (v16i8) in3);  \
-}
-#define ILVR_B2_SH(...) ILVR_B2(v8i16, __VA_ARGS__)
-
-#define HSUB_UB2(RTYPE, in0, in1, out0, out1)                 \
-{                                                             \
-    out0 = (RTYPE) __msa_hsub_u_h((v16u8) in0, (v16u8) in0);  \
-    out1 = (RTYPE) __msa_hsub_u_h((v16u8) in1, (v16u8) in1);  \
-}
-#define HSUB_UB2_SH(...) HSUB_UB2(v8i16, __VA_ARGS__)
-
-#define SLDI_B2_0(RTYPE, in0, in1, out0, out1, slide_val)                 \
-{                                                                         \
-    v16i8 zero_m = { 0 };                                                 \
-    out0 = (RTYPE) __msa_sldi_b((v16i8) zero_m, (v16i8) in0, slide_val);  \
-    out1 = (RTYPE) __msa_sldi_b((v16i8) zero_m, (v16i8) in1, slide_val);  \
-}
-#define SLDI_B2_0_UB(...) SLDI_B2_0(v16u8, __VA_ARGS__)
-
-#define SLDI_B3_0(RTYPE, in0, in1, in2, out0, out1, out2,  slide_val)     \
-{                                                                         \
-    v16i8 zero_m = { 0 };                                                 \
-    SLDI_B2_0(RTYPE, in0, in1, out0, out1, slide_val);                    \
-    out2 = (RTYPE) __msa_sldi_b((v16i8) zero_m, (v16i8) in2, slide_val);  \
-}
-#define SLDI_B3_0_UB(...) SLDI_B3_0(v16u8, __VA_ARGS__)
-
-#define ILVEV_W2(RTYPE, in0, in1, in2, in3, out0, out1)      \
-{                                                            \
-    out0 = (RTYPE) __msa_ilvev_w((v4i32) in1, (v4i32) in0);  \
-    out1 = (RTYPE) __msa_ilvev_w((v4i32) in3, (v4i32) in2);  \
-}
-#define ILVEV_W2_UB(...) ILVEV_W2(v16u8, __VA_ARGS__)
-
-#define ADD_ABS_H3(RTYPE, in0, in1, in2, out0, out1, out2)  \
-{                                                           \
-    RTYPE zero = {0};                                       \
-                                                            \
-    out0 = __msa_add_a_h((v8i16) zero, in0);                \
-    out1 = __msa_add_a_h((v8i16) zero, in1);                \
-    out2 = __msa_add_a_h((v8i16) zero, in2);                \
-}
-#define ADD_ABS_H3_SH(...) ADD_ABS_H3(v8i16, __VA_ARGS__)
-
-#define VSHF_B2(RTYPE, in0, in1, in2, in3, mask0, mask1, out0, out1)       \
-{                                                                          \
-    out0 = (RTYPE) __msa_vshf_b((v16i8) mask0, (v16i8) in1, (v16i8) in0);  \
-    out1 = (RTYPE) __msa_vshf_b((v16i8) mask1, (v16i8) in3, (v16i8) in2);  \
-}
-#define VSHF_B2_UB(...) VSHF_B2(v16u8, __VA_ARGS__)
-
-#define CMP_AND_SELECT(inp0, inp1, inp2, inp3, inp4, inp5, out0)              \
-{                                                                             \
-   v8i16 _sel_h0, _sel_h1;                                                    \
-   v16u8 _sel_b0, _sel_b1;                                                    \
-   _sel_h0 = (v8i16) __msa_clt_u_h((v8u16) inp1, (v8u16) inp0);               \
-   _sel_b0 = (v16u8) __msa_pckev_b((v16i8) _sel_h0, (v16i8) _sel_h0);         \
-   inp0 = (v8i16) __msa_bmnz_v((v16u8) inp0, (v16u8) inp1, (v16u8) _sel_h0);  \
-   inp4 = (v16u8) __msa_bmnz_v(inp3, inp4, _sel_b0);                          \
-   _sel_h1 = (v8i16) __msa_clt_u_h((v8u16) inp2, (v8u16) inp0);               \
-   _sel_b1 = (v16u8) __msa_pckev_b((v16i8) _sel_h1, (v16i8) _sel_h1);         \
-   inp4 = (v16u8) __msa_bmnz_v(inp4, inp5, _sel_b1);                          \
-   out0 += inp4;                                                              \
-}
-
-void png_read_filter_row_up_msa(png_row_infop row_info, png_bytep row,
-                                png_const_bytep prev_row)
-{
-   png_size_t i, cnt, cnt16, cnt32;
-   png_size_t istop = row_info->rowbytes;
-   png_bytep rp = row;
-   png_const_bytep pp = prev_row;
-   v16u8 src0, src1, src2, src3, src4, src5, src6, src7;
-
-   for (i = 0; i < (istop >> 6); i++)
-   {
-      LD_UB4(rp, 16, src0, src1, src2, src3);
-      LD_UB4(pp, 16, src4, src5, src6, src7);
-      pp += 64;
-
-	  ADD4(src0, src4, src1, src5, src2, src6, src3, src7,
-	       src0, src1, src2, src3);
-
-      ST_UB4(src0, src1, src2, src3, rp, 16);
-      rp += 64;
-   }
-
-   if (istop & 0x3F)
-   {
-      cnt32 = istop & 0x20;
-      cnt16 = istop & 0x10;
-      cnt = istop & 0xF;
-
-      if(cnt32)
-      {
-         if (cnt16 && cnt)
-         {
-            LD_UB4(rp, 16, src0, src1, src2, src3);
-            LD_UB4(pp, 16, src4, src5, src6, src7);
-
-            ADD4(src0, src4, src1, src5, src2, src6, src3, src7,
-	             src0, src1, src2, src3);
-
-            ST_UB4(src0, src1, src2, src3, rp, 16);
-            rp += 64;
-         }
-         else if (cnt16 || cnt)
-         {
-            LD_UB2(rp, 16, src0, src1);
-            LD_UB2(pp, 16, src4, src5);
-            pp += 32;
-            src2 = LD_UB(rp + 32);
-            src6 = LD_UB(pp);
-
-            ADD3(src0, src4, src1, src5, src2, src6, src0, src1, src2);
-
-            ST_UB2(src0, src1, rp, 16);
-            rp += 32;
-            ST_UB(src2, rp);
-            rp += 16;
-         }
-         else
-         {
-            LD_UB2(rp, 16, src0, src1);
-            LD_UB2(pp, 16, src4, src5);
-
-			ADD2(src0, src4, src1, src5, src0, src1);
-
-            ST_UB2(src0, src1, rp, 16);
-            rp += 32;
-         }
-      }
-      else if (cnt16 && cnt)
-      {
-         LD_UB2(rp, 16, src0, src1);
-         LD_UB2(pp, 16, src4, src5);
-
-         ADD2(src0, src4, src1, src5, src0, src1);
-
-         ST_UB2(src0, src1, rp, 16);
-         rp += 32;
-      }
-      else if (cnt16 || cnt)
-      {
-         src0 = LD_UB(rp);
-         src4 = LD_UB(pp);
-         pp += 16;
-
-         src0 += src4;
-
-         ST_UB(src0, rp);
-         rp += 16;
-      }
-   }
-}
-
-void png_read_filter_row_sub4_msa(png_row_infop row_info, png_bytep row,
-                                  png_const_bytep prev_row)
-{
-   png_size_t count;
-   png_size_t istop = row_info->rowbytes;
-   png_bytep src = row;
-   png_bytep nxt = row + 4;
-   int32_t inp0;
-   v16u8 src0, src1, src2, src3, src4;
-   v16u8 dst0, dst1;
-   v16u8 zero = { 0 };
-
-   istop -= 4;
-
-   inp0 = LW(src);
-   src += 4;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-
-   for (count = 0; count < istop; count += 16)
-   {
-      src1 = LD_UB(src);
-      src += 16;
-
-      src2 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 4);
-      src3 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 8);
-      src4 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 12);
-      src1 += src0;
-      src2 += src1;
-      src3 += src2;
-      src4 += src3;
-      src0 = src4;
-      ILVEV_W2_UB(src1, src2, src3, src4, dst0, dst1);
-      dst0 = (v16u8) __msa_pckev_d((v2i64) dst1, (v2i64) dst0);
-
-      ST_UB(dst0, nxt);
-      nxt += 16;
-   }
-}
-
-void png_read_filter_row_sub3_msa(png_row_infop row_info, png_bytep row,
-                                  png_const_bytep prev_row)
-{
-   png_size_t count;
-   png_size_t istop = row_info->rowbytes;
-   png_bytep src = row;
-   png_bytep nxt = row + 3;
-   int64_t out0;
-   int32_t inp0, out1;
-   v16u8 src0, src1, src2, src3, src4, dst0, dst1;
-   v16u8 zero = { 0 };
-   v16i8 mask0 = { 0, 1, 2, 16, 17, 18, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
-   v16i8 mask1 = { 0, 1, 2, 3, 4, 5, 16, 17, 18, 19, 20, 21, 0, 0, 0, 0 };
-
-   istop -= 3;
-
-   inp0 = LW(src);
-   src += 3;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-
-   for (count = 0; count < istop; count += 12)
-   {
-      src1 = LD_UB(src);
-      src += 12;
-
-      src2 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 3);
-      src3 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 6);
-      src4 = (v16u8) __msa_sldi_b((v16i8) zero, (v16i8) src1, 9);
-      src1 += src0;
-      src2 += src1;
-      src3 += src2;
-      src4 += src3;
-      src0 = src4;
-      VSHF_B2_UB(src1, src2, src3, src4, mask0, mask0, dst0, dst1);
-      dst0 = (v16u8) __msa_vshf_b(mask1, (v16i8) dst1, (v16i8) dst0);
-      out0 = __msa_copy_s_d((v2i64) dst0, 0);
-      out1 = __msa_copy_s_w((v4i32) dst0, 2);
-
-      SD(out0, nxt);
-      nxt += 8;
-      SW(out1, nxt);
-      nxt += 4;
-   }
-}
-
-void png_read_filter_row_avg4_msa(png_row_infop row_info, png_bytep row,
-                                  png_const_bytep prev_row)
-{
-   png_size_t i;
-   png_bytep src = row;
-   png_bytep nxt = row;
-   png_const_bytep pp = prev_row;
-   png_size_t istop = row_info->rowbytes - 4;
-   int32_t inp0, inp1, out0;
-   v16u8 src0, src1, src2, src3, src4, src5, src6, src7, src8, src9, dst0, dst1;
-   v16u8 zero = { 0 };
-
-   inp0 = LW(pp);
-   pp += 4;
-   inp1 = LW(src);
-   src += 4;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-   src1 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp1);
-   src0 = (v16u8) MSA_SRLI_B(src0, 1);
-   src1 += src0;
-   out0 = __msa_copy_s_w((v4i32) src1, 0);
-   SW(out0, nxt);
-   nxt += 4;
-
-   for (i = 0; i < istop; i += 16)
-   {
-      src2 = LD_UB(pp);
-      pp += 16;
-      src6 = LD_UB(src);
-      src += 16;
-
-      SLDI_B2_0_UB(src2, src6, src3, src7, 4);
-      SLDI_B2_0_UB(src2, src6, src4, src8, 8);
-      SLDI_B2_0_UB(src2, src6, src5, src9, 12);
-      src2 = __msa_ave_u_b(src2, src1);
-      src6 += src2;
-      src3 = __msa_ave_u_b(src3, src6);
-      src7 += src3;
-      src4 = __msa_ave_u_b(src4, src7);
-      src8 += src4;
-      src5 = __msa_ave_u_b(src5, src8);
-      src9 += src5;
-      src1 = src9;
-      ILVEV_W2_UB(src6, src7, src8, src9, dst0, dst1);
-      dst0 = (v16u8) __msa_pckev_d((v2i64) dst1, (v2i64) dst0);
-
-      ST_UB(dst0, nxt);
-      nxt += 16;
-   }
-}
-
-void png_read_filter_row_avg3_msa(png_row_infop row_info, png_bytep row,
-                                  png_const_bytep prev_row)
-{
-   png_size_t i;
-   png_bytep src = row;
-   png_bytep nxt = row;
-   png_const_bytep pp = prev_row;
-   png_size_t istop = row_info->rowbytes - 3;
-   int64_t out0;
-   int32_t inp0, inp1, out1;
-   int16_t out2;
-   v16u8 src0, src1, src2, src3, src4, src5, src6, src7, src8, src9, dst0, dst1;
-   v16u8 zero = { 0 };
-   v16i8 mask0 = { 0, 1, 2, 16, 17, 18, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
-   v16i8 mask1 = { 0, 1, 2, 3, 4, 5, 16, 17, 18, 19, 20, 21, 0, 0, 0, 0 };
-
-   inp0 = LW(pp);
-   pp += 3;
-   inp1 = LW(src);
-   src += 3;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-   src1 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp1);
-   src0 = (v16u8) MSA_SRLI_B(src0, 1);
-   src1 += src0;
-   out2 = __msa_copy_s_h((v8i16) src1, 0);
-   SH(out2, nxt);
-   nxt += 2;
-   nxt[0] = src1[2];
-   nxt++;
-
-   for (i = 0; i < istop; i += 12)
-   {
-      src2 = LD_UB(pp);
-      pp += 12;
-      src6 = LD_UB(src);
-      src += 12;
-
-      SLDI_B2_0_UB(src2, src6, src3, src7, 3);
-      SLDI_B2_0_UB(src2, src6, src4, src8, 6);
-      SLDI_B2_0_UB(src2, src6, src5, src9, 9);
-      src2 = __msa_ave_u_b(src2, src1);
-      src6 += src2;
-      src3 = __msa_ave_u_b(src3, src6);
-      src7 += src3;
-      src4 = __msa_ave_u_b(src4, src7);
-      src8 += src4;
-      src5 = __msa_ave_u_b(src5, src8);
-      src9 += src5;
-      src1 = src9;
-      VSHF_B2_UB(src6, src7, src8, src9, mask0, mask0, dst0, dst1);
-      dst0 = (v16u8) __msa_vshf_b(mask1, (v16i8) dst1, (v16i8) dst0);
-      out0 = __msa_copy_s_d((v2i64) dst0, 0);
-      out1 = __msa_copy_s_w((v4i32) dst0, 2);
-
-      SD(out0, nxt);
-      nxt += 8;
-      SW(out1, nxt);
-      nxt += 4;
-   }
-}
-
-void png_read_filter_row_paeth4_msa(png_row_infop row_info,
-                                    png_bytep row,
-                                    png_const_bytep prev_row)
-{
-   int32_t count, rp_end;
-   png_bytep nxt;
-   png_const_bytep prev_nxt;
-   int32_t inp0, inp1, res0;
-   v16u8 src0, src1, src2, src3, src4, src5, src6, src7, src8, src9;
-   v16u8 src10, src11, src12, src13, dst0, dst1;
-   v8i16 vec0, vec1, vec2;
-   v16u8 zero = { 0 };
-
-   nxt = row;
-   prev_nxt = prev_row;
-
-   inp0 = LW(nxt);
-   inp1 = LW(prev_nxt);
-   prev_nxt += 4;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-   src1 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp1);
-
-   src1 += src0;
-   res0 = __msa_copy_s_w((v4i32) src1, 0);
-
-   SW(res0, nxt);
-   nxt += 4;
-
-   /* Remainder */
-   rp_end = row_info->rowbytes - 4;
-
-   for (count = 0; count < rp_end; count += 16)
-   {
-      src2 = LD_UB(prev_nxt);
-      prev_nxt += 16;
-      src6 = LD_UB(prev_row);
-      prev_row += 16;
-      src10 = LD_UB(nxt);
-
-      SLDI_B3_0_UB(src2, src6, src10, src3, src7, src11, 4);
-      SLDI_B3_0_UB(src2, src6, src10, src4, src8, src12, 8);
-      SLDI_B3_0_UB(src2, src6, src10, src5, src9, src13, 12);
-      ILVR_B2_SH(src2, src6, src1, src6, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src1, src2, src6, src10);
-      ILVR_B2_SH(src3, src7, src10, src7, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src10, src3, src7, src11);
-      ILVR_B2_SH(src4, src8, src11, src8, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src11, src4, src8, src12);
-      ILVR_B2_SH(src5, src9, src12, src9, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src12, src5, src9, src13);
-      src1 = src13;
-      ILVEV_W2_UB(src10, src11, src12, src1, dst0, dst1);
-      dst0 = (v16u8) __msa_pckev_d((v2i64) dst1, (v2i64) dst0);
-
-      ST_UB(dst0, nxt);
-      nxt += 16;
-   }
-}
-
-void png_read_filter_row_paeth3_msa(png_row_infop row_info,
-                                    png_bytep row,
-                                    png_const_bytep prev_row)
-{
-   int32_t count, rp_end;
-   png_bytep nxt;
-   png_const_bytep prev_nxt;
-   int64_t out0;
-   int32_t inp0, inp1, out1;
-   int16_t out2;
-   v16u8 src0, src1, src2, src3, src4, src5, src6, src7, src8, src9, dst0, dst1;
-   v16u8 src10, src11, src12, src13;
-   v8i16 vec0, vec1, vec2;
-   v16u8 zero = { 0 };
-   v16i8 mask0 = { 0, 1, 2, 16, 17, 18, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
-   v16i8 mask1 = { 0, 1, 2, 3, 4, 5, 16, 17, 18, 19, 20, 21, 0, 0, 0, 0 };
-
-   nxt = row;
-   prev_nxt = prev_row;
-
-   inp0 = LW(nxt);
-   inp1 = LW(prev_nxt);
-   prev_nxt += 3;
-   src0 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp0);
-   src1 = (v16u8) __msa_insert_w((v4i32) zero, 0, inp1);
-
-   src1 += src0;
-   out2 = __msa_copy_s_h((v8i16) src1, 0);
-
-   SH(out2, nxt);
-   nxt += 2;
-   nxt[0] = src1[2];
-   nxt++;
-
-   /* Remainder */
-   rp_end = row_info->rowbytes - 3;
-
-   for (count = 0; count < rp_end; count += 12)
-   {
-      src2 = LD_UB(prev_nxt);
-      prev_nxt += 12;
-      src6 = LD_UB(prev_row);
-      prev_row += 12;
-      src10 = LD_UB(nxt);
-
-      SLDI_B3_0_UB(src2, src6, src10, src3, src7, src11, 3);
-      SLDI_B3_0_UB(src2, src6, src10, src4, src8, src12, 6);
-      SLDI_B3_0_UB(src2, src6, src10, src5, src9, src13, 9);
-      ILVR_B2_SH(src2, src6, src1, src6, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src1, src2, src6, src10);
-      ILVR_B2_SH(src3, src7, src10, src7, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src10, src3, src7, src11);
-      ILVR_B2_SH(src4, src8, src11, src8, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src11, src4, src8, src12);
-      ILVR_B2_SH(src5, src9, src12, src9, vec0, vec1);
-      HSUB_UB2_SH(vec0, vec1, vec0, vec1);
-      vec2 = vec0 + vec1;
-      ADD_ABS_H3_SH(vec0, vec1, vec2, vec0, vec1, vec2);
-      CMP_AND_SELECT(vec0, vec1, vec2, src12, src5, src9, src13);
-      src1 = src13;
-      VSHF_B2_UB(src10, src11, src12, src13, mask0, mask0, dst0, dst1);
-      dst0 = (v16u8) __msa_vshf_b(mask1, (v16i8) dst1, (v16i8) dst0);
-      out0 = __msa_copy_s_d((v2i64) dst0, 0);
-      out1 = __msa_copy_s_w((v4i32) dst0, 2);
-
-      SD(out0, nxt);
-      nxt += 8;
-      SW(out1, nxt);
-      nxt += 4;
-   }
-}
-
-#endif /* PNG_MIPS_MSA_OPT > 0 */
-#endif /* PNG_MIPS_MSA_IMPLEMENTATION == 1 (intrinsics) */
-#endif /* READ */
--- a/mips/mips_init.c
+++ b/mips/mips_init.c
@@ -1,129 +0,0 @@
-
-/* mips_init.c - MSA optimised filter functions
- *
- * Copyright (c) 2016 Glenn Randers-Pehrson
- * Written by Mandar Sahastrabuddhe, 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
- * called.
- */
-#define _POSIX_SOURCE 1
-
-#include <stdio.h>
-#include "../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-#if PNG_MIPS_MSA_OPT > 0
-#ifdef PNG_MIPS_MSA_CHECK_SUPPORTED /* Do run-time checks */
-/* WARNING: it is strongly recommended that you do not build libpng with
- * run-time checks for CPU features if at all possible.  In the case of the MIPS
- * MSA instructions there is no processor-specific way of detecting the
- * presence of the required support, therefore run-time detection is extremely
- * OS specific.
- *
- * You may set the macro PNG_MIPS_MSA_FILE to the file name of file containing
- * a fragment of C source code which defines the png_have_msa function.  There
- * are a number of implementations in contrib/mips-msa, but the only one that
- * has partial support is contrib/mips-msa/linux.c - a generic Linux
- * implementation which reads /proc/cpufino.
- */
-#ifndef PNG_MIPS_MSA_FILE
-#  ifdef __linux__
-#     define PNG_MIPS_MSA_FILE "contrib/mips-msa/linux.c"
-#  endif
-#endif
-
-#ifdef PNG_MIPS_MSA_FILE
-
-#include <signal.h> /* for sig_atomic_t */
-static int png_have_msa(png_structp png_ptr);
-#include PNG_MIPS_MSA_FILE
-
-#else  /* PNG_MIPS_MSA_FILE */
-#  error "PNG_MIPS_MSA_FILE undefined: no support for run-time MIPS MSA checks"
-#endif /* PNG_MIPS_MSA_FILE */
-#endif /* PNG_MIPS_MSA_CHECK_SUPPORTED */
-
-#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
-#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
-#endif
-
-void
-png_init_filter_functions_msa(png_structp pp, unsigned int bpp)
-{
-   /* The switch statement is compiled in for MIPS_MSA_API, the call to
-    * png_have_msa is compiled in for MIPS_MSA_CHECK. If both are defined
-    * the check is only performed if the API has not set the MSA option on
-    * or off explicitly. In this case the check controls what happens.
-    */
-
-#ifdef PNG_MIPS_MSA_API_SUPPORTED
-   switch ((pp->options >> PNG_MIPS_MSA) & 3)
-   {
-      case PNG_OPTION_UNSET:
-         /* Allow the run-time check to execute if it has been enabled -
-          * thus both API and CHECK can be turned on.  If it isn't supported
-          * this case will fall through to the 'default' below, which just
-          * returns.
-          */
-#endif /* PNG_MIPS_MSA_API_SUPPORTED */
-#ifdef PNG_MIPS_MSA_CHECK_SUPPORTED
-         {
-            static volatile sig_atomic_t no_msa = -1; /* not checked */
-
-            if (no_msa < 0)
-               no_msa = !png_have_msa(pp);
-
-            if (no_msa)
-               return;
-         }
-#ifdef PNG_MIPS_MSA_API_SUPPORTED
-         break;
-#endif
-#endif /* PNG_MIPS_MSA_CHECK_SUPPORTED */
-
-#ifdef PNG_MIPS_MSA_API_SUPPORTED
-      default: /* OFF or INVALID */
-         return;
-
-      case PNG_OPTION_ON:
-         /* Option turned on */
-         break;
-   }
-#endif
-
-   /* IMPORTANT: any new external functions used here must be declared using
-    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
-    * 'prefix' option to configure works:
-    *
-    *    ./configure --with-libpng-prefix=foobar_
-    *
-    * Verify you have got this right by running the above command, doing a build
-    * and examining pngprefix.h; it must contain a #define for every external
-    * function you add.  (Notice that this happens automatically for the
-    * initialization function.)
-    */
-   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_msa;
-
-   if (bpp == 3)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_msa;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_msa;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth3_msa;
-   }
-
-   else if (bpp == 4)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_msa;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_msa;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth4_msa;
-   }
-}
-#endif /* PNG_MIPS_MSA_OPT > 0 */
-#endif /* READ */
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "September 1, 2016"
+.TH PNG 5 "January 15, 2016"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
@@ -35,7 +35,7 @@ PNG 1.0 specification, October 1996:
 RFC 2083
 .IP
 .br
-http://www.ietf.org/rfc/rfc2083.txt
+ftp://ds.internic.net/rfc/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
--- a/png.c
+++ b/png.c
@@ -1,8 +1,8 @@

 /* png.c - location for general purpose libpng functions
 *
- * Last changed in libpng 1.6.25 [September 1, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -14,7 +14,7 @@
 #include "pngpriv.h"

 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_25 Your_png_h_is_not_version_1_6_25;
+typedef png_libpng_version_1_6_21 Your_png_h_is_not_version_1_6_21;

 /* Tells libpng that we have already handled the first "num_bytes" bytes
 * of the PNG file signature.  If the PNG data is embedded into another
@@ -85,7 +85,7 @@ png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
   if (items >= (~(png_alloc_size_t)0)/size)
   {
      png_warning (png_voidcast(png_structrp, png_ptr),
-          "Potential overflow in png_zalloc()");
+         "Potential overflow in png_zalloc()");
      return NULL;
   }

@@ -172,10 +172,10 @@ png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
 int
 png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
 {
-   /* Libpng versions 1.0.0 and later are binary compatible if the version
-    * string matches through the second '.'; we must recompile any
-    * applications that use any older library version.
-    */
+     /* Libpng versions 1.0.0 and later are binary compatible if the version
+      * string matches through the second '.'; we must recompile any
+      * applications that use any older library version.
+      */

   if (user_png_ver != NULL)
   {
@@ -297,7 +297,7 @@ png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
         if (png_user_version_check(&create_struct, user_png_ver) != 0)
         {
            png_structrp png_ptr = png_voidcast(png_structrp,
-                png_malloc_warn(&create_struct, (sizeof *png_ptr)));
+               png_malloc_warn(&create_struct, (sizeof *png_ptr)));

            if (png_ptr != NULL)
            {
@@ -346,7 +346,7 @@ png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
    * has always been done in 'example.c'.
    */
   info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
-       (sizeof *info_ptr)));
+      (sizeof *info_ptr)));

   if (info_ptr != NULL)
      memset(info_ptr, 0, (sizeof *info_ptr));
@@ -402,7 +402,7 @@ png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
 */
 PNG_FUNCTION(void,PNGAPI
 png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
-    PNG_DEPRECATED)
+   PNG_DEPRECATED)
 {
   png_inforp info_ptr = *ptr_ptr;

@@ -417,7 +417,7 @@ png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
      /* The following line is why this API should not be used: */
      free(info_ptr);
      info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
-          (sizeof *info_ptr)));
+         (sizeof *info_ptr)));
      if (info_ptr == NULL)
         return;
      *ptr_ptr = info_ptr;
@@ -430,7 +430,7 @@ png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
 /* The following API is not called internally */
 void PNGAPI
 png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
-    int freer, png_uint_32 mask)
+   int freer, png_uint_32 mask)
 {
   png_debug(1, "in png_data_freer");

@@ -449,7 +449,7 @@ png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,

 void PNGAPI
 png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
-    int num)
+   int num)
 {
   png_debug(1, "in png_free_data");

@@ -775,14 +775,14 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
   return PNG_STRING_NEWLINE \
-      "libpng version 1.6.25 - September 1, 2016" PNG_STRING_NEWLINE \
+      "libpng version 1.6.21 - January 15, 2016" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
      PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
-   return "libpng version 1.6.25 - September 1, 2016\
+   return "libpng version 1.6.21 - January 15, 2016\
      Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
      Copyright (c) 1996-1997 Andreas Dilger\
      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -1033,7 +1033,7 @@ png_zstream_error(png_structrp png_ptr, int ret)
 #ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
 static int
 png_colorspace_check_gamma(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, png_fixed_point gAMA, int from)
+   png_colorspacerp colorspace, png_fixed_point gAMA, int from)
   /* This is called to check a new gamma value against an existing one.  The
    * routine returns false if the new gamma value should not be written.
    *
@@ -1047,7 +1047,7 @@ png_colorspace_check_gamma(png_const_structrp png_ptr,
   png_fixed_point gtest;

   if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
-       (png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) == 0  ||
+      (png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) == 0  ||
      png_gamma_significant(gtest) != 0))
   {
      /* Either this is an sRGB image, in which case the calculated gamma
@@ -1059,7 +1059,7 @@ png_colorspace_check_gamma(png_const_structrp png_ptr,
      if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
      {
         png_chunk_report(png_ptr, "gamma value does not match sRGB",
-             PNG_CHUNK_ERROR);
+            PNG_CHUNK_ERROR);
         /* Do not overwrite an sRGB value */
         return from == 2;
      }
@@ -1067,7 +1067,7 @@ png_colorspace_check_gamma(png_const_structrp png_ptr,
      else /* sRGB tag not involved */
      {
         png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
-             PNG_CHUNK_WARNING);
+            PNG_CHUNK_WARNING);
         return from == 1;
      }
   }
@@ -1077,7 +1077,7 @@ png_colorspace_check_gamma(png_const_structrp png_ptr,

 void /* PRIVATE */
 png_colorspace_set_gamma(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, png_fixed_point gAMA)
+   png_colorspacerp colorspace, png_fixed_point gAMA)
 {
   /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
    * occur.  Since the fixed point representation is asymetrical it is
@@ -1635,8 +1635,8 @@ static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */

 static int
 png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
-    int preferred)
+   png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
+   int preferred)
 {
   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;
@@ -1683,7 +1683,7 @@ png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,

 int /* PRIVATE */
 png_colorspace_set_chromaticities(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, const png_xy *xy, int preferred)
+   png_colorspacerp colorspace, const png_xy *xy, int preferred)
 {
   /* We must check the end points to ensure they are reasonable - in the past
    * color management systems have crashed as a result of getting bogus
@@ -1697,7 +1697,7 @@ png_colorspace_set_chromaticities(png_const_structrp png_ptr,
   {
      case 0: /* success */
         return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
-             preferred);
+            preferred);

      case 1:
         /* We can't invert the chromaticities so we can't produce value XYZ
@@ -1720,7 +1720,7 @@ png_colorspace_set_chromaticities(png_const_structrp png_ptr,

 int /* PRIVATE */
 png_colorspace_set_endpoints(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
+   png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
 {
   png_XYZ XYZ = *XYZ_in;
   png_xy xy;
@@ -1729,7 +1729,7 @@ png_colorspace_set_endpoints(png_const_structrp png_ptr,
   {
      case 0:
         return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
-             preferred);
+            preferred);

      case 1:
         /* End points are invalid. */
@@ -1786,7 +1786,7 @@ is_ICC_signature(png_alloc_size_t it)

 static int
 png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_alloc_size_t value, png_const_charp reason)
+   png_const_charp name, png_alloc_size_t value, png_const_charp reason)
 {
   size_t pos;
   char message[196]; /* see below for calculation */
@@ -1811,8 +1811,8 @@ png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
         char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/

         pos = png_safecat(message, (sizeof message), pos,
-             png_format_number(number, number+(sizeof number),
-             PNG_NUMBER_FORMAT_x, value));
+            png_format_number(number, number+(sizeof number),
+               PNG_NUMBER_FORMAT_x, value));
         pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
      }
 #  endif
@@ -1826,7 +1826,7 @@ png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
    * application errors the PNG won't be written.)
    */
   png_chunk_report(png_ptr, message,
-       (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
+      (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);

   return 0;
 }
@@ -1835,7 +1835,7 @@ png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
 #ifdef PNG_sRGB_SUPPORTED
 int /* PRIVATE */
 png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    int intent)
+   int intent)
 {
   /* sRGB sets known gamma, end points and (from the chunk) intent. */
   /* IMPORTANT: these are not necessarily the values found in an ICC profile
@@ -1872,10 +1872,10 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
    */
   if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
-          (unsigned)intent, "invalid sRGB rendering intent");
+         (unsigned)intent, "invalid sRGB rendering intent");

   if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
-       colorspace->rendering_intent != intent)
+      colorspace->rendering_intent != intent)
      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
         (unsigned)intent, "inconsistent rendering intents");

@@ -1889,8 +1889,8 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
    * warn but overwrite the value with the correct one.
    */
   if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
-       !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
-       100))
+      !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
+         100))
      png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
         PNG_CHUNK_ERROR);

@@ -1898,7 +1898,7 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
    * returns true when the 'from' argument corresponds to sRGB (2).
    */
   (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
-       2/*from sRGB*/);
+      2/*from sRGB*/);

   /* intent: bugs in GCC force 'int' to be used as the parameter type. */
   colorspace->rendering_intent = (png_uint_16)intent;
@@ -1931,55 +1931,21 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
 static const png_byte D50_nCIEXYZ[12] =
   { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };

-static int /* bool */
-icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_uint_32 profile_length)
+int /* PRIVATE */
+png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_uint_32 profile_length)
 {
   if (profile_length < 132)
      return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
-          "too short");
+         "too short");

   return 1;
 }

-#ifdef PNG_READ_iCCP_SUPPORTED
-int /* PRIVATE */
-png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_uint_32 profile_length)
-{
-   if (!icc_check_length(png_ptr, colorspace, name, profile_length))
-      return 0;
-
-   /* This needs to be here because the 'normal' check is in
-    * png_decompress_chunk, yet this happens after the attempt to
-    * png_malloc_base the required data.  We only need this on read; on write
-    * the caller supplies the profile buffer so libpng doesn't allocate it.  See
-    * the call to icc_check_length below (the write case).
-    */
-#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
-      else if (png_ptr->user_chunk_malloc_max > 0 &&
-               png_ptr->user_chunk_malloc_max < profile_length)
-         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
-             "exceeds application limits");
-#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
-      else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
-         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
-             "exceeds libpng limits");
-#  else /* !SET_USER_LIMITS */
-      /* This will get compiled out on all 32-bit and better systems. */
-      else if (PNG_SIZE_MAX < profile_length)
-         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
-             "exceeds system limits");
-#  endif /* !SET_USER_LIMITS */
-
-   return 1;
-}
-#endif /* READ_iCCP */
-
 int /* PRIVATE */
 png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_uint_32 profile_length,
-    png_const_bytep profile/* first 132 bytes only */, int color_type)
+   png_const_charp name, png_uint_32 profile_length,
+   png_const_bytep profile/* first 132 bytes only */, int color_type)
 {
   png_uint_32 temp;

@@ -1991,18 +1957,18 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
   temp = png_get_uint_32(profile);
   if (temp != profile_length)
      return png_icc_profile_error(png_ptr, colorspace, name, temp,
-          "length does not match profile");
+         "length does not match profile");

   temp = (png_uint_32) (*(profile+8));
   if (temp > 3 && (profile_length & 3))
      return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
-          "invalid length");
+         "invalid length");

   temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
   if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
      profile_length < 132+12*temp) /* truncated tag table */
      return png_icc_profile_error(png_ptr, colorspace, name, temp,
-          "tag count too large");
+         "tag count too large");

   /* The 'intent' must be valid or we can't store it, ICC limits the intent to
    * 16 bits.
@@ -2010,14 +1976,14 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
   temp = png_get_uint_32(profile+64);
   if (temp >= 0xffff) /* The ICC limit */
      return png_icc_profile_error(png_ptr, colorspace, name, temp,
-          "invalid rendering intent");
+         "invalid rendering intent");

   /* This is just a warning because the profile may be valid in future
    * versions.
    */
   if (temp >= PNG_sRGB_INTENT_LAST)
      (void)png_icc_profile_error(png_ptr, NULL, name, temp,
-          "intent outside defined range");
+         "intent outside defined range");

   /* At this point the tag table can't be checked because it hasn't necessarily
    * been loaded; however, various header fields can be checked.  These checks
@@ -2034,7 +2000,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
   temp = png_get_uint_32(profile+36); /* signature 'ascp' */
   if (temp != 0x61637370)
      return png_icc_profile_error(png_ptr, colorspace, name, temp,
-          "invalid signature");
+         "invalid signature");

   /* Currently the PCS illuminant/adopted white point (the computational
    * white point) are required to be D50,
@@ -2045,7 +2011,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
    */
   if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
      (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
-          "PCS illuminant is not D50");
+         "PCS illuminant is not D50");

   /* The PNG spec requires this:
    * "If the iCCP chunk is present, the image samples conform to the colour
@@ -2073,18 +2039,18 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
      case 0x52474220: /* 'RGB ' */
         if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
            return png_icc_profile_error(png_ptr, colorspace, name, temp,
-                "RGB color space not permitted on grayscale PNG");
+               "RGB color space not permitted on grayscale PNG");
         break;

      case 0x47524159: /* 'GRAY' */
         if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
            return png_icc_profile_error(png_ptr, colorspace, name, temp,
-                "Gray color space not permitted on RGB PNG");
+               "Gray color space not permitted on RGB PNG");
         break;

      default:
         return png_icc_profile_error(png_ptr, colorspace, name, temp,
-             "invalid ICC profile color space");
+            "invalid ICC profile color space");
   }

   /* It is up to the application to check that the profile class matches the
@@ -2109,7 +2075,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
      case 0x61627374: /* 'abst' */
         /* May not be embedded in an image */
         return png_icc_profile_error(png_ptr, colorspace, name, temp,
-             "invalid embedded Abstract ICC profile");
+            "invalid embedded Abstract ICC profile");

      case 0x6c696e6b: /* 'link' */
         /* DeviceLink profiles cannot be interpreted in a non-device specific
@@ -2119,7 +2085,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
          * PNG.
          */
         return png_icc_profile_error(png_ptr, colorspace, name, temp,
-             "unexpected DeviceLink ICC profile class");
+            "unexpected DeviceLink ICC profile class");

      case 0x6e6d636c: /* 'nmcl' */
         /* A NamedColor profile is also device specific, however it doesn't
@@ -2127,7 +2093,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
          * certainly it will fail the tests below.
          */
         (void)png_icc_profile_error(png_ptr, NULL, name, temp,
-             "unexpected NamedColor ICC profile class");
+            "unexpected NamedColor ICC profile class");
         break;

      default:
@@ -2137,7 +2103,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
          * understood profiles.
          */
         (void)png_icc_profile_error(png_ptr, NULL, name, temp,
-             "unrecognized ICC profile class");
+            "unrecognized ICC profile class");
         break;
   }

@@ -2153,7 +2119,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,

      default:
         return png_icc_profile_error(png_ptr, colorspace, name, temp,
-             "unexpected ICC PCS encoding");
+            "unexpected ICC PCS encoding");
   }

   return 1;
@@ -2161,8 +2127,8 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,

 int /* PRIVATE */
 png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_uint_32 profile_length,
-    png_const_bytep profile /* header plus whole tag table */)
+   png_const_charp name, png_uint_32 profile_length,
+   png_const_bytep profile /* header plus whole tag table */)
 {
   png_uint_32 tag_count = png_get_uint_32(profile+128);
   png_uint_32 itag;
@@ -2190,7 +2156,7 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
          * alignment.
          */
         (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
-             "ICC profile tag start not a multiple of 4");
+            "ICC profile tag start not a multiple of 4");
      }

      /* This is a hard error; potentially it can cause read outside the
@@ -2198,7 +2164,7 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
       */
      if (tag_start > profile_length || tag_length > profile_length - tag_start)
         return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
-             "ICC profile tag outside profile");
+            "ICC profile tag outside profile");
   }

   return 1; /* success, maybe with warnings */
@@ -2226,22 +2192,22 @@ static const struct
    */
   /* adler32, crc32, MD5[4], intent, date, length, file-name */
   PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
-       PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
-       "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
+      PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
+      "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")

   /* ICC sRGB v2 perceptual no black-compensation: */
   PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
-       PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
-       "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
+      PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
+      "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")

   PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
-       PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
-       "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
+      PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
+      "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")

   /* ICC sRGB v4 perceptual */
   PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
-       PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
-       "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
+      PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
+      "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")

   /* The following profiles have no known MD5 checksum. If there is a match
    * on the (empty) MD5 the other fields are used to attempt a match and
@@ -2249,8 +2215,8 @@ static const struct
    * which suggests that they were also made by Hewlett Packard.
    */
   PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
-       PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
-       "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
+      "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")

   /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
    * match the D50 PCS illuminant in the header (it is in fact the D65 values,
@@ -2260,17 +2226,17 @@ static const struct
    * chromaticAdaptationTag.
    */
   PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
-       PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
-       "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
+      "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")

   PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
-       PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
-       "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
+      "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
 };

 static int
 png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
-    png_const_bytep profile, uLong adler)
+   png_const_bytep profile, uLong adler)
 {
   /* The quick check is to verify just the MD5 signature and trust the
    * rest of the data.  Because the profile has already been verified for
@@ -2354,7 +2320,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
                      * which is made irrelevant by this error.
                      */
                     png_chunk_report(png_ptr, "known incorrect sRGB profile",
-                         PNG_CHUNK_ERROR);
+                        PNG_CHUNK_ERROR);
                  }

                  /* Warn that this being done; this isn't even an error since
@@ -2364,8 +2330,8 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
                  else if (png_sRGB_checks[i].have_md5 == 0)
                  {
                     png_chunk_report(png_ptr,
-                         "out-of-date sRGB profile with no signature",
-                         PNG_CHUNK_WARNING);
+                        "out-of-date sRGB profile with no signature",
+                        PNG_CHUNK_WARNING);
                  }

                  return 1+png_sRGB_checks[i].is_broken;
@@ -2388,36 +2354,38 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,

   return 0; /* no match */
 }
+#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */

 void /* PRIVATE */
 png_icc_set_sRGB(png_const_structrp png_ptr,
-    png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
+   png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
 {
   /* Is this profile one of the known ICC sRGB profiles?  If it is, just set
    * the sRGB information.
    */
+#if PNG_sRGB_PROFILE_CHECKS >= 0
   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
+#endif
      (void)png_colorspace_set_sRGB(png_ptr, colorspace,
         (int)/*already checked*/png_get_uint_32(profile+64));
 }
-#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
 #endif /* sRGB */

 int /* PRIVATE */
 png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
-    png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
-    int color_type)
+   png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
+   int color_type)
 {
   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;

-   if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
+   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
       png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
-           color_type) != 0 &&
+          color_type) != 0 &&
       png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
-           profile) != 0)
+          profile) != 0)
   {
-#     if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
+#     ifdef PNG_sRGB_SUPPORTED
         /* If no sRGB support, don't try storing sRGB information */
         png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
 #     endif
@@ -2476,7 +2444,7 @@ png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
         /* Check for an internal error. */
         if (r+g+b != 32768)
            png_error(png_ptr,
-                "internal error handling cHRM coefficients");
+               "internal error handling cHRM coefficients");

         else
         {
@@ -2502,7 +2470,7 @@ png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
 static int /* PRIVATE */
 png_gt(size_t a, size_t b)
 {
-   return a > b;
+    return a > b;
 }
 #else
 #   define png_gt(a,b) ((a) > (b))
@@ -2510,9 +2478,9 @@ png_gt(size_t a, size_t b)

 void /* PRIVATE */
 png_check_IHDR(png_const_structrp png_ptr,
-    png_uint_32 width, png_uint_32 height, int bit_depth,
-    int color_type, int interlace_type, int compression_type,
-    int filter_type)
+   png_uint_32 width, png_uint_32 height, int bit_depth,
+   int color_type, int interlace_type, int compression_type,
+   int filter_type)
 {
   int error = 0;

@@ -2675,7 +2643,7 @@ png_check_IHDR(png_const_structrp png_ptr,

 int /* PRIVATE */
 png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
-    png_size_tp whereami)
+   png_size_tp whereami)
 {
   int state = *statep;
   png_size_t i = *whereami;
@@ -3838,25 +3806,25 @@ png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
 {
   if (value > 0 && value < 65535)
   {
-# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
-      /* The same (unsigned int)->(double) constraints apply here as above,
-       * however in this case the (unsigned int) to (int) conversion can
-       * overflow on an ANSI-C90 compliant system so the cast needs to ensure
-       * that this is not possible.
-       */
-      double r = floor(65535*pow((png_int_32)value/65535.,
-          gamma_val*.00001)+.5);
-      return (png_uint_16)r;
-# else
-      png_int_32 lg2 = png_log16bit(value);
-      png_fixed_point res;
+#     ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+         /* The same (unsigned int)->(double) constraints apply here as above,
+          * however in this case the (unsigned int) to (int) conversion can
+          * overflow on an ANSI-C90 compliant system so the cast needs to ensure
+          * that this is not possible.
+          */
+         double r = floor(65535*pow((png_int_32)value/65535.,
+                     gamma_val*.00001)+.5);
+         return (png_uint_16)r;
+#     else
+         png_int_32 lg2 = png_log16bit(value);
+         png_fixed_point res;

-      if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
-         return png_exp16bit(res);
+         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
+            return png_exp16bit(res);

-      /* Overflow. */
-      value = 0;
-# endif
+         /* Overflow. */
+         value = 0;
+#     endif
   }

   return (png_uint_16)value;
@@ -3895,7 +3863,7 @@ png_gamma_correct(png_structrp png_ptr, unsigned int value,
 */
 static void
 png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
-    PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+   PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
 {
   /* Various values derived from 'shift': */
   PNG_CONST unsigned int num = 1U << (8U - shift);
@@ -3972,7 +3940,7 @@ png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
 */
 static void
 png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
-    PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+   PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
 {
   PNG_CONST unsigned int num = 1U << (8U - shift);
   PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
@@ -4040,7 +4008,7 @@ png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
 */
 static void
 png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
-    PNG_CONST png_fixed_point gamma_val)
+   PNG_CONST png_fixed_point gamma_val)
 {
   unsigned int i;
   png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
@@ -4120,133 +4088,131 @@ png_destroy_gamma_table(png_structrp png_ptr)
 void /* PRIVATE */
 png_build_gamma_table(png_structrp png_ptr, int bit_depth)
 {
-   png_debug(1, "in png_build_gamma_table");
+  png_debug(1, "in png_build_gamma_table");

-   /* Remove any existing table; this copes with multiple calls to
-    * png_read_update_info. The warning is because building the gamma tables
-    * multiple times is a performance hit - it's harmless but the ability to
-    * call png_read_update_info() multiple times is new in 1.5.6 so it seems
-    * sensible to warn if the app introduces such a hit.
-    */
-   if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
-   {
-      png_warning(png_ptr, "gamma table being rebuilt");
-      png_destroy_gamma_table(png_ptr);
-   }
+  /* Remove any existing table; this copes with multiple calls to
+   * png_read_update_info.  The warning is because building the gamma tables
+   * multiple times is a performance hit - it's harmless but the ability to call
+   * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
+   * to warn if the app introduces such a hit.
+   */
+  if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
+  {
+    png_warning(png_ptr, "gamma table being rebuilt");
+    png_destroy_gamma_table(png_ptr);
+  }

-   if (bit_depth <= 8)
-   {
-      png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
-          png_ptr->screen_gamma > 0 ?
-          png_reciprocal2(png_ptr->colorspace.gamma,
-          png_ptr->screen_gamma) : PNG_FP_1);
+  if (bit_depth <= 8)
+  {
+     png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
+         png_ptr->screen_gamma > 0 ?  png_reciprocal2(png_ptr->colorspace.gamma,
+         png_ptr->screen_gamma) : PNG_FP_1);

 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-      if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
-      {
-         png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
-             png_reciprocal(png_ptr->colorspace.gamma));
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
+     {
+        png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
+            png_reciprocal(png_ptr->colorspace.gamma));

-         png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
-             png_ptr->screen_gamma > 0 ?
-             png_reciprocal(png_ptr->screen_gamma) :
-             png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
-      }
+        png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
+            png_ptr->screen_gamma > 0 ?  png_reciprocal(png_ptr->screen_gamma) :
+            png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+     }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
-   }
+  }
 #ifdef PNG_16BIT_SUPPORTED
-   else
-   {
-      png_byte shift, sig_bit;
+  else
+  {
+     png_byte shift, sig_bit;

-      if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
-      {
-         sig_bit = png_ptr->sig_bit.red;
+     if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
+     {
+        sig_bit = png_ptr->sig_bit.red;

-         if (png_ptr->sig_bit.green > sig_bit)
-            sig_bit = png_ptr->sig_bit.green;
+        if (png_ptr->sig_bit.green > sig_bit)
+           sig_bit = png_ptr->sig_bit.green;

-         if (png_ptr->sig_bit.blue > sig_bit)
-            sig_bit = png_ptr->sig_bit.blue;
-      }
-      else
-         sig_bit = png_ptr->sig_bit.gray;
+        if (png_ptr->sig_bit.blue > sig_bit)
+           sig_bit = png_ptr->sig_bit.blue;
+     }
+     else
+        sig_bit = png_ptr->sig_bit.gray;

-      /* 16-bit gamma code uses this equation:
-       *
-       *   ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
-       *
-       * Where 'iv' is the input color value and 'ov' is the output value -
-       * pow(iv, gamma).
-       *
-       * Thus the gamma table consists of up to 256 256-entry tables.  The table
-       * is selected by the (8-gamma_shift) most significant of the low 8 bits
-       * of the color value then indexed by the upper 8 bits:
-       *
-       *   table[low bits][high 8 bits]
-       *
-       * So the table 'n' corresponds to all those 'iv' of:
-       *
-       *   <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
-       *
-       */
-      if (sig_bit > 0 && sig_bit < 16U)
-         /* shift == insignificant bits */
-         shift = (png_byte)((16U - sig_bit) & 0xff);
+     /* 16-bit gamma code uses this equation:
+      *
+      *   ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
+      *
+      * Where 'iv' is the input color value and 'ov' is the output value -
+      * pow(iv, gamma).
+      *
+      * Thus the gamma table consists of up to 256 256-entry tables.  The table
+      * is selected by the (8-gamma_shift) most significant of the low 8 bits of
+      * the color value then indexed by the upper 8 bits:
+      *
+      *   table[low bits][high 8 bits]
+      *
+      * So the table 'n' corresponds to all those 'iv' of:
+      *
+      *   <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
+      *
+      */
+     if (sig_bit > 0 && sig_bit < 16U)
+        /* shift == insignificant bits */
+        shift = (png_byte)((16U - sig_bit) & 0xff);

-      else
-         shift = 0; /* keep all 16 bits */
+     else
+        shift = 0; /* keep all 16 bits */

-      if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
-      {
-         /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
-          * the significant bits in the *input* when the output will
-          * eventually be 8 bits.  By default it is 11.
-          */
-         if (shift < (16U - PNG_MAX_GAMMA_8))
-            shift = (16U - PNG_MAX_GAMMA_8);
-      }
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
+     {
+        /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
+         * the significant bits in the *input* when the output will
+         * eventually be 8 bits.  By default it is 11.
+         */
+        if (shift < (16U - PNG_MAX_GAMMA_8))
+           shift = (16U - PNG_MAX_GAMMA_8);
+     }

-      if (shift > 8U)
-         shift = 8U; /* Guarantees at least one table! */
+     if (shift > 8U)
+        shift = 8U; /* Guarantees at least one table! */

-      png_ptr->gamma_shift = shift;
+     png_ptr->gamma_shift = shift;

-      /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
-       * PNG_COMPOSE).  This effectively smashed the background calculation for
-       * 16-bit output because the 8-bit table assumes the result will be
-       * reduced to 8 bits.
-       */
-      if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
-          png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
-          png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
-          png_ptr->screen_gamma) : PNG_FP_1);
+     /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
+      * PNG_COMPOSE).  This effectively smashed the background calculation for
+      * 16-bit output because the 8-bit table assumes the result will be reduced
+      * to 8 bits.
+      */
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
+         png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
+         png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
+         png_ptr->screen_gamma) : PNG_FP_1);

-      else
-          png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
-          png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
-          png_ptr->screen_gamma) : PNG_FP_1);
+     else
+         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
+         png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
+         png_ptr->screen_gamma) : PNG_FP_1);

 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-      if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
-      {
-         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
-             png_reciprocal(png_ptr->colorspace.gamma));
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
+     {
+        png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
+            png_reciprocal(png_ptr->colorspace.gamma));

-         /* Notice that the '16 from 1' table should be full precision, however
-          * the lookup on this table still uses gamma_shift, so it can't be.
-          * TODO: fix this.
-          */
-         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
-             png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
-             png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
-      }
+        /* Notice that the '16 from 1' table should be full precision, however
+         * the lookup on this table still uses gamma_shift, so it can't be.
+         * TODO: fix this.
+         */
+        png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
+            png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
+            png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+     }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
-   }
+  }
 #endif /* 16BIT */
 }
 #endif /* READ_GAMMA */
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@

 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.25, September 1, 2016
+ * libpng version 1.6.21, January 15, 2016
 *
 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@
 * Authors and maintainers:
 *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
 *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.25, September 1, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.21, January 15, 2016:
 *     Glenn Randers-Pehrson.
 *   See also "Contributing Authors", below.
 */
@@ -25,11 +25,7 @@
 *
 * This code is released under the libpng license.
 *
- * Some files in the "contrib" directory and some configure-generated
- * files that are distributed with libpng have other copyright owners and
- * are released under other open source licenses.
- *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+ * libpng versions 1.0.7, July 1, 2000, through 1.6.21, January 15, 2016, are
 * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 * derived from libpng-1.0.6, and are distributed according to the same
 * disclaimer and license as libpng-1.0.6 with the following individuals
@@ -41,7 +37,6 @@
 *    Cosmin Truta
 *    Gilles Vollant
 *    James Yu
- *    Mandar Sahastrabuddhe
 *
 * and with the following additions to the disclaimer:
 *
@@ -52,10 +47,6 @@
 *    risk of satisfactory quality, performance, accuracy, and effort is with
 *    the user.
 *
- * Some files in the "contrib" directory have other copyright owners and
- * are released under other open source licenses.
- *
- *
 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 * libpng-0.96, and are distributed according to the same disclaimer and
@@ -66,9 +57,6 @@
 *    Glenn Randers-Pehrson
 *    Willem van Schaik
 *
- * Some files in the "scripts" directory have different copyright owners
- * but are also released under this license.
- *
 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
 * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
 * and are distributed according to the same disclaimer and license as
@@ -82,9 +70,6 @@
 *    Greg Roelofs
 *    Tom Tanner
 *
- * Some files in the "scripts" directory have other copyright owners
- * but are released under this license.
- *
 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
@@ -124,29 +109,6 @@
 * appreciated.
 *
 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
- *
- * TRADEMARK:
- *
- * The name "libpng" has not been registered by the Copyright owner
- * as a trademark in any jurisdiction.  However, because libpng has
- * been distributed and maintained world-wide, continually since 1995,
- * the Copyright owner claims "common-law trademark protection" in any
- * jurisdiction where common-law trademark is recognized.
- *
- * OSI CERTIFICATION:
- *
- * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
- * a certification mark of the Open Source Initiative. OSI has not addressed
- * the additional disclaimers inserted at version 1.0.7.
- *
- * EXPORT CONTROL:
- *
- * The Copyright owner believes that the Export Control Classification
- * Number (ECCN) for libpng is EAR99, which means not subject to export
- * controls or International Traffic in Arms Regulations (ITAR) because
- * it is open source, publicly available software, that does not contain
- * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
- * 734.7(b).
 */

 /*
@@ -159,6 +121,12 @@
 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
 */

+/*
+ * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
+ * a certification mark of the Open Source Initiative. OSI has not addressed
+ * the additional disclaimers inserted at version 1.0.7.
+ */
+
 /*
 * The contributing authors would like to thank all those who helped
 * with testing, bug fixes, and patience.  This wouldn't have been
@@ -214,11 +182,11 @@
 *    ...
 *    1.0.19                  10    10019  10.so.0.19[.0]
 *    ...
- *    1.2.56                  13    10256  12.so.0.56[.0]
+ *    1.2.53                  13    10253  12.so.0.53[.0]
 *    ...
- *    1.5.27                  15    10527  15.so.15.27[.0]
+ *    1.5.23                  15    10523  15.so.15.23[.0]
 *    ...
- *    1.6.25                  16    10625  16.so.16.25[.0]
+ *    1.6.21                  16    10621  16.so.16.21[.0]
 *
 *    Henceforth the source version will match the shared-library major
 *    and minor numbers; the shared-library major version number will be
@@ -246,13 +214,13 @@
 * Y2K compliance in libpng:
 * =========================
 *
- *    September 1, 2016
+ *    January 15, 2016
 *
 *    Since the PNG Development group is an ad-hoc body, we can't make
 *    an official declaration.
 *
 *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.6.25 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.21 are Y2K compliant.  It is my belief that
 *    earlier versions were also Y2K compliant.
 *
 *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -314,8 +282,9 @@
 */

 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.25"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.25 - September 1, 2016\n"
+#define PNG_LIBPNG_VER_STRING "1.6.21"
+#define PNG_HEADER_VERSION_STRING \
+     " libpng version 1.6.21 - January 15, 2016\n"

 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -323,7 +292,7 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 25
+#define PNG_LIBPNG_VER_RELEASE 21

 /* This should match the numeric part of the final component of
 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -354,20 +323,20 @@
 * version 1.0.0 was mis-numbered 100 instead of 10000).  From
 * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
 */
-#define PNG_LIBPNG_VER 10625 /* 1.6.25 */
+#define PNG_LIBPNG_VER 10621 /* 1.6.21 */

 /* Library configuration: these options cannot be changed after
 * the library has been built.
 */
 #ifndef PNGLCONF_H
-/* If pnglibconf.h is missing, you can
- * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
- */
+    /* If pnglibconf.h is missing, you can
+     * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
+     */
 #   include "pnglibconf.h"
 #endif

 #ifndef PNG_VERSION_INFO_ONLY
-/* Machine specific configuration. */
+   /* Machine specific configuration. */
 #  include "pngconf.h"
 #endif

@@ -464,7 +433,7 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
 * do not agree upon the version number.
 */
-typedef char* png_libpng_version_1_6_25;
+typedef char* png_libpng_version_1_6_21;

 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
@@ -657,17 +626,17 @@ typedef png_time * * png_timepp;
 */
 typedef struct png_unknown_chunk_t
 {
-   png_byte name[5]; /* Textual chunk name with '\0' terminator */
-   png_byte *data;   /* Data, should not be modified on read! */
-   png_size_t size;
+    png_byte name[5]; /* Textual chunk name with '\0' terminator */
+    png_byte *data;   /* Data, should not be modified on read! */
+    png_size_t size;

-   /* On write 'location' must be set using the flag values listed below.
-    * Notice that on read it is set by libpng however the values stored have
-    * more bits set than are listed below.  Always treat the value as a
-    * bitmask.  On write set only one bit - setting multiple bits may cause the
-    * chunk to be written in multiple places.
-    */
-   png_byte location; /* mode of operation at read time */
+    /* On write 'location' must be set using the flag values listed below.
+     * Notice that on read it is set by libpng however the values stored have
+     * more bits set than are listed below.  Always treat the value as a
+     * bitmask.  On write set only one bit - setting multiple bits may cause the
+     * chunk to be written in multiple places.
+     */
+    png_byte location; /* mode of operation at read time */
 }
 png_unknown_chunk;

@@ -765,22 +734,24 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 * data in the info_struct to be written into the output file.  The values
 * of the PNG_INFO_<chunk> defines should NOT be changed.
 */
-#define PNG_INFO_gAMA 0x0001U
-#define PNG_INFO_sBIT 0x0002U
-#define PNG_INFO_cHRM 0x0004U
-#define PNG_INFO_PLTE 0x0008U
-#define PNG_INFO_tRNS 0x0010U
-#define PNG_INFO_bKGD 0x0020U
-#define PNG_INFO_hIST 0x0040U
-#define PNG_INFO_pHYs 0x0080U
-#define PNG_INFO_oFFs 0x0100U
-#define PNG_INFO_tIME 0x0200U
-#define PNG_INFO_pCAL 0x0400U
-#define PNG_INFO_sRGB 0x0800U  /* GR-P, 0.96a */
-#define PNG_INFO_iCCP 0x1000U  /* ESR, 1.0.6 */
-#define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
-#define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
-#define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
+#define PNG_INFO_gAMA 0x0001
+#define PNG_INFO_sBIT 0x0002
+#define PNG_INFO_cHRM 0x0004
+#define PNG_INFO_PLTE 0x0008
+#define PNG_INFO_tRNS 0x0010
+#define PNG_INFO_bKGD 0x0020
+#define PNG_INFO_hIST 0x0040
+#define PNG_INFO_pHYs 0x0080
+#define PNG_INFO_oFFs 0x0100
+#define PNG_INFO_tIME 0x0200
+#define PNG_INFO_pCAL 0x0400
+#define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
+#define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
+#define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
+#define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
+#if INT_MAX >= 0x8000 /* else this might break */
+#define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
+#endif

 /* This is used for the transformation routines, as some of them
 * change these values for the row.  It also should enable using
@@ -1351,7 +1322,7 @@ PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
 #endif

 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-#define PNG_READ_16_TO_8_SUPPORTED /* Name prior to 1.5.4 */
+#define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
 /* Strip the second byte of information from a 16-bit depth file. */
 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
 #endif
@@ -1502,8 +1473,8 @@ PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
 #define PNG_FILTER_UP      0x20
 #define PNG_FILTER_AVG     0x40
 #define PNG_FILTER_PAETH   0x80
-#define PNG_FAST_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP)
-#define PNG_ALL_FILTERS (PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH)
+#define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
+                         PNG_FILTER_AVG | PNG_FILTER_PAETH)

 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
 * These defines should NOT be changed.
@@ -1780,21 +1751,21 @@ PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
 #define PNG_SET_WILL_FREE_DATA 1
 #define PNG_USER_WILL_FREE_DATA 2
 /* Flags for png_ptr->free_me and info_ptr->free_me */
-#define PNG_FREE_HIST 0x0008U
-#define PNG_FREE_ICCP 0x0010U
-#define PNG_FREE_SPLT 0x0020U
-#define PNG_FREE_ROWS 0x0040U
-#define PNG_FREE_PCAL 0x0080U
-#define PNG_FREE_SCAL 0x0100U
+#define PNG_FREE_HIST 0x0008
+#define PNG_FREE_ICCP 0x0010
+#define PNG_FREE_SPLT 0x0020
+#define PNG_FREE_ROWS 0x0040
+#define PNG_FREE_PCAL 0x0080
+#define PNG_FREE_SCAL 0x0100
 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-#  define PNG_FREE_UNKN 0x0200U
+#  define PNG_FREE_UNKN 0x0200
 #endif
-/*      PNG_FREE_LIST 0x0400U   removed in 1.6.0 because it is ignored */
-#define PNG_FREE_PLTE 0x1000U
-#define PNG_FREE_TRNS 0x2000U
-#define PNG_FREE_TEXT 0x4000U
-#define PNG_FREE_ALL  0x7fffU
-#define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
+/*      PNG_FREE_LIST 0x0400    removed in 1.6.0 because it is ignored */
+#define PNG_FREE_PLTE 0x1000
+#define PNG_FREE_TRNS 0x2000
+#define PNG_FREE_TEXT 0x4000
+#define PNG_FREE_ALL  0x7fff
+#define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */

 #ifdef PNG_USER_MEM_SUPPORTED
 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
@@ -2300,10 +2271,8 @@ PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
 *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
 *    be processed by libpng.
 */
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
    int keep, png_const_bytep chunk_list, int num_chunks));
-#endif /* HANDLE_AS_UNKNOWN */

 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
 * the result is therefore true (non-zero) if special handling is required,
@@ -2311,7 +2280,7 @@ PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
 */
 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
    png_const_bytep chunk_name));
-#endif /* SET_UNKNOWN_CHUNKS */
+#endif

 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
@@ -2532,37 +2501,33 @@ PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,

 /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */

-#  define png_composite(composite, fg, alpha, bg)        \
-   {                                                     \
-      png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
-          * (png_uint_16)(alpha)                         \
-          + (png_uint_16)(bg)*(png_uint_16)(255          \
-          - (png_uint_16)(alpha)) + 128);                \
-      (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); \
-   }
+#  define png_composite(composite, fg, alpha, bg)         \
+     { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
+           * (png_uint_16)(alpha)                         \
+           + (png_uint_16)(bg)*(png_uint_16)(255          \
+           - (png_uint_16)(alpha)) + 128);                \
+       (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }

-#  define png_composite_16(composite, fg, alpha, bg)     \
-   {                                                     \
-      png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
-          * (png_uint_32)(alpha)                         \
-          + (png_uint_32)(bg)*(65535                     \
-          - (png_uint_32)(alpha)) + 32768);              \
-      (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); \
-   }
+#  define png_composite_16(composite, fg, alpha, bg)       \
+     { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
+           * (png_uint_32)(alpha)                          \
+           + (png_uint_32)(bg)*(65535                      \
+           - (png_uint_32)(alpha)) + 32768);               \
+       (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }

 #else  /* Standard method using integer division */

-#  define png_composite(composite, fg, alpha, bg)                      \
-   (composite) =                                                       \
-       (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
-       (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
-       127) / 255))
+#  define png_composite(composite, fg, alpha, bg)                        \
+     (composite) =                                                       \
+         (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
+         (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
+         127) / 255))

-#  define png_composite_16(composite, fg, alpha, bg)                       \
-   (composite) =                                                           \
-       (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
-       (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
-       32767) / 65535))
+#  define png_composite_16(composite, fg, alpha, bg)                         \
+     (composite) =                                                           \
+         (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+         (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
+         32767) / 65535))
 #endif /* READ_COMPOSITE_NODIV */

 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
@@ -2598,38 +2563,38 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
 * format for negative values, which is almost certainly true.
 */
 #  define PNG_get_uint_32(buf) \
-   (((png_uint_32)(*(buf)) << 24) + \
-    ((png_uint_32)(*((buf) + 1)) << 16) + \
-    ((png_uint_32)(*((buf) + 2)) << 8) + \
-    ((png_uint_32)(*((buf) + 3))))
+     (((png_uint_32)(*(buf)) << 24) + \
+      ((png_uint_32)(*((buf) + 1)) << 16) + \
+      ((png_uint_32)(*((buf) + 2)) << 8) + \
+      ((png_uint_32)(*((buf) + 3))))

   /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
    * function) incorrectly returned a value of type png_uint_32.
    */
 #  define PNG_get_uint_16(buf) \
-   ((png_uint_16) \
-    (((unsigned int)(*(buf)) << 8) + \
-    ((unsigned int)(*((buf) + 1)))))
+     ((png_uint_16) \
+      (((unsigned int)(*(buf)) << 8) + \
+       ((unsigned int)(*((buf) + 1)))))

 #  define PNG_get_int_32(buf) \
-   ((png_int_32)((*(buf) & 0x80) \
-    ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
-    : (png_int_32)png_get_uint_32(buf)))
+     ((png_int_32)((*(buf) & 0x80) \
+      ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
+      : (png_int_32)png_get_uint_32(buf)))

-/* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
- * but defining a macro name prefixed with PNG_PREFIX.
- */
+   /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
+    * but defining a macro name prefixed with PNG_PREFIX.
+    */
 #  ifndef PNG_PREFIX
-#    define png_get_uint_32(buf) PNG_get_uint_32(buf)
-#    define png_get_uint_16(buf) PNG_get_uint_16(buf)
-#    define png_get_int_32(buf)  PNG_get_int_32(buf)
+#     define png_get_uint_32(buf) PNG_get_uint_32(buf)
+#     define png_get_uint_16(buf) PNG_get_uint_16(buf)
+#     define png_get_int_32(buf)  PNG_get_int_32(buf)
 #  endif
 #else
 #  ifdef PNG_PREFIX
-   /* No macros; revert to the (redefined) function */
-#    define PNG_get_uint_32 (png_get_uint_32)
-#    define PNG_get_uint_16 (png_get_uint_16)
-#    define PNG_get_int_32  (png_get_int_32)
+      /* No macros; revert to the (redefined) function */
+#     define PNG_get_uint_32 (png_get_uint_32)
+#     define PNG_get_uint_16 (png_get_uint_16)
+#     define PNG_get_int_32  (png_get_int_32)
 #  endif
 #endif

@@ -2924,19 +2889,12 @@ typedef struct
    * is the minimum 'row stride', the minimum count of components between each
    * row.  For a color-mapped image this is the minimum number of bytes in a
    * row.
-    *
-    * WARNING: this macro overflows for some images with more than one component
-    * and very large image widths.  libpng will refuse to process an image where
-    * this macro would overflow.
    */

 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
   (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
   /* Return the size, in bytes, of an image buffer given a png_image and a row
    * stride - the number of components to leave space for in each row.
-    *
-    * WARNING: this macro overflows a 32-bit integer for some large PNG images,
-    * libpng will refuse to process an image where such an overflow would occur.
    */

 #define PNG_IMAGE_SIZE(image)\
@@ -3057,6 +3015,7 @@ PNG_EXPORT(238, void, png_image_free, (png_imagep image));
 #endif /* SIMPLIFIED_READ */

 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED
 /* WRITE APIS
 * ----------
 * For write you must initialize a png_image structure to describe the image to
@@ -3073,7 +3032,6 @@ PNG_EXPORT(238, void, png_image_free, (png_imagep image));
 *    values do not correspond to the colors in sRGB.
 * colormap_entries: set to the number of entries in the color-map (0 to 256)
 */
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
   const char *file, int convert_to_8bit, const void *buffer,
   png_int_32 row_stride, const void *colormap));
@@ -3083,9 +3041,8 @@ PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
   int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
   const void *colormap));
   /* Write the image to the given (FILE*). */
-#endif /* SIMPLIFIED_WRITE_STDIO */

-/* With all write APIs if image is in one of the linear formats with 16-bit
+/* With both write APIs if image is in one of the linear formats with 16-bit
 * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
 * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
 * encoded PNG file is written.
@@ -3097,103 +3054,13 @@ PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
 *
 * With all APIs row_stride is handled as in the read APIs - it is the spacing
 * from one row to the next in component sized units (1 or 2 bytes) and if
- * negative indicates a bottom-up row layout in the buffer.  If row_stride is
- * zero, libpng will calculate it for you from the image width and number of
- * channels.
+ * negative indicates a bottom-up row layout in the buffer.  If row_stride is zero,
+ * libpng will calculate it for you from the image width and number of channels.
 *
- * Note that the write API does not support interlacing, sub-8-bit pixels or
- * most ancillary chunks.  If you need to write text chunks (e.g. for copyright
- * notices) you need to use one of the other APIs.
+ * Note that the write API does not support interlacing, sub-8-bit pixels, indexed
+ * PNG (color_type 3) or most ancillary chunks.
 */
-
-PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
-   png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8_bit,
-   const void *buffer, png_int_32 row_stride, const void *colormap));
-   /* Write the image to the given memory buffer.  The function both writes the
-    * whole PNG data stream to *memory and updates *memory_bytes with the count
-    * of bytes written.
-    *
-    * 'memory' may be NULL.  In this case *memory_bytes is not read however on
-    * success the number of bytes which would have been written will still be
-    * stored in *memory_bytes.  On failure *memory_bytes will contain 0.
-    *
-    * If 'memory' is not NULL it must point to memory[*memory_bytes] of
-    * writeable memory.
-    *
-    * If the function returns success memory[*memory_bytes] (if 'memory' is not
-    * NULL) contains the written PNG data.  *memory_bytes will always be less
-    * than or equal to the original value.
-    *
-    * If the function returns false and *memory_bytes was not changed an error
-    * occured during write.  If *memory_bytes was changed, or is not 0 if
-    * 'memory' was NULL, the write would have succeeded but for the memory
-    * buffer being too small.  *memory_bytes contains the required number of
-    * bytes and will be bigger that the original value.
-    */
-
-#define png_image_write_get_memory_size(image, size, convert_to_8_bit, buffer,\
-   row_stride, colormap)\
-   png_image_write_to_memory(&(image), 0, &(size), convert_to_8_bit, buffer,\
-         row_stride, colormap)
-   /* Return the amount of memory in 'size' required to compress this image.
-    * The png_image structure 'image' must be filled in as in the above
-    * function and must not be changed before the actual write call, the buffer
-    * and all other parameters must also be identical to that in the final
-    * write call.  The 'size' variable need not be initialized.
-    *
-    * NOTE: the macro returns true/false, if false is returned 'size' will be
-    * set to zero and the write failed and probably will fail if tried again.
-    */
-
-/* You can pre-allocate the buffer by making sure it is of sufficient size
- * regardless of the amount of compression achieved.  The buffer size will
- * always be bigger than the original image and it will never be filled.  The
- * following macros are provided to assist in allocating the buffer.
- */
-#define PNG_IMAGE_DATA_SIZE(image) (PNG_IMAGE_SIZE(image)+(image).height)
-   /* The number of uncompressed bytes in the PNG byte encoding of the image;
-    * uncompressing the PNG IDAT data will give this number of bytes.
-    *
-    * NOTE: while PNG_IMAGE_SIZE cannot overflow for an image in memory this
-    * macro can because of the extra bytes used in the PNG byte encoding.  You
-    * need to avoid this macro if your image size approaches 2^30 in width or
-    * height.  The same goes for the remainder of these macros; they all produce
-    * bigger numbers than the actual in-memory image size.
-    */
-#ifndef PNG_ZLIB_MAX_SIZE
-#  define PNG_ZLIB_MAX_SIZE(b) ((b)+(((b)+7U)>>3)+(((b)+63U)>>6)+11U)
-   /* An upper bound on the number of compressed bytes given 'b' uncompressed
-    * bytes.  This is based on deflateBounds() in zlib; different
-    * implementations of zlib compression may conceivably produce more data so
-    * if your zlib implementation is not zlib itself redefine this macro
-    * appropriately.
-    */
-#endif
-
-#define PNG_IMAGE_COMPRESSED_SIZE_MAX(image)\
-   PNG_ZLIB_MAX_SIZE((png_alloc_size_t)PNG_IMAGE_DATA_SIZE(image))
-   /* An upper bound on the size of the data in the PNG IDAT chunks. */
-
-#define PNG_IMAGE_PNG_SIZE_MAX_(image, image_size)\
-   ((8U/*sig*/+25U/*IHDR*/+16U/*gAMA*/+44U/*cHRM*/+12U/*IEND*/+\
-    (((image).format&PNG_FORMAT_FLAG_COLORMAP)?/*colormap: PLTE, tRNS*/\
-    12U+3U*(image).colormap_entries/*PLTE data*/+\
-    (((image).format&PNG_FORMAT_FLAG_ALPHA)?\
-    12U/*tRNS*/+(image).colormap_entries:0U):0U)+\
-    12U)+(12U*((image_size)/PNG_ZBUF_SIZE))/*IDAT*/+(image_size))
-   /* A helper for the following macro; if your compiler cannot handle the
-    * following macro use this one with the result of
-    * PNG_IMAGE_COMPRESSED_SIZE_MAX(image) as the second argument (most
-    * compilers should handle this just fine.)
-    */
-
-#define PNG_IMAGE_PNG_SIZE_MAX(image)\
-   PNG_IMAGE_PNG_SIZE_MAX_(image, PNG_IMAGE_COMPRESSED_SIZE_MAX(image))
-   /* An upper bound on the total length of the PNG data stream for 'image'.
-    * The result is of type png_alloc_size_t, on 32-bit systems this may
-    * overflow even though PNG_IMAGE_DATA_SIZE does not overflow; the write will
-    * run out of buffer space but return a corrected size which should work.
-    */
+#endif /* STDIO */
 #endif /* SIMPLIFIED_WRITE */
 /*******************************************************************************
 *  END OF SIMPLIFIED API
@@ -3227,10 +3094,7 @@ PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
 #endif
 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
 #define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
-#ifdef PNG_MIPS_MSA_API_SUPPORTED
-#  define PNG_MIPS_MSA   6 /* HARDWARE: MIPS Msa SIMD instructions supported */
-#endif
-#define PNG_OPTION_NEXT  8 /* Next option - numbers must be even */
+#define PNG_OPTION_NEXT  6 /* Next option - numbers must be even */

 /* Return values: NOTE: there are four values and 'off' is *not* zero */
 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
@@ -3254,7 +3118,7 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
 * one to use is one more than this.)
 */
 #ifdef PNG_EXPORT_LAST_ORDINAL
-  PNG_EXPORT_LAST_ORDINAL(245);
+  PNG_EXPORT_LAST_ORDINAL(244);
 #endif

 #ifdef __cplusplus
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,9 +1,9 @@

 /* pngconf.h - machine configurable file for libpng
 *
- * libpng version 1.6.25, September 1, 2016
+ * libpng version 1.6.21, January 15, 2016
 *
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -188,27 +188,27 @@
   * compatible with GCC or Visual C because of different calling conventions.
   */
 #  if PNG_API_RULE == 2
-   /* If this line results in an error, either because __watcall is not
-    * understood or because of a redefine just below you cannot use *this*
-    * build of the library with the compiler you are using.  *This* build was
-    * build using Watcom and applications must also be built using Watcom!
-    */
+    /* If this line results in an error, either because __watcall is not
+     * understood or because of a redefine just below you cannot use *this*
+     * build of the library with the compiler you are using.  *This* build was
+     * build using Watcom and applications must also be built using Watcom!
+     */
 #    define PNGCAPI __watcall
 #  endif

 #  if defined(__GNUC__) || (defined(_MSC_VER) && (_MSC_VER >= 800))
 #    define PNGCAPI __cdecl
 #    if PNG_API_RULE == 1
-   /* If this line results in an error __stdcall is not understood and
-    * PNG_API_RULE should not have been set to '1'.
-    */
+       /* If this line results in an error __stdcall is not understood and
+        * PNG_API_RULE should not have been set to '1'.
+        */
 #      define PNGAPI __stdcall
 #    endif
 #  else
-   /* An older compiler, or one not detected (erroneously) above,
-    * if necessary override on the command line to get the correct
-    * variants for the compiler.
-    */
+    /* An older compiler, or one not detected (erroneously) above,
+     * if necessary override on the command line to get the correct
+     * variants for the compiler.
+     */
 #    ifndef PNGCAPI
 #      define PNGCAPI _cdecl
 #    endif
@@ -225,10 +225,10 @@

 #  if (defined(_MSC_VER) && _MSC_VER < 800) ||\
      (defined(__BORLANDC__) && __BORLANDC__ < 0x500)
-   /* older Borland and MSC
-    * compilers used '__export' and required this to be after
-    * the type.
-    */
+    /* older Borland and MSC
+     * compilers used '__export' and required this to be after
+     * the type.
+     */
 #    ifndef PNG_EXPORT_TYPE
 #      define PNG_EXPORT_TYPE(type) type PNG_IMPEXP
 #    endif
@@ -244,9 +244,9 @@
 #  if (defined(__IBMC__) || defined(__IBMCPP__)) && defined(__OS2__)
 #    define PNGAPI _System
 #  else /* !Windows/x86 && !OS/2 */
-   /* Use the defaults, or define PNG*API on the command line (but
-    * this will have to be done for every compile!)
-    */
+    /* Use the defaults, or define PNG*API on the command line (but
+     * this will have to be done for every compile!)
+     */
 #  endif /* other system, !OS/2 */
 #endif /* !Windows/x86 */

@@ -267,7 +267,7 @@
 */
 #ifndef PNG_IMPEXP
 #  if defined(PNG_USE_DLL) && defined(PNG_DLL_IMPORT)
-   /* This forces use of a DLL, disallowing static linking */
+     /* This forces use of a DLL, disallowing static linking */
 #    define PNG_IMPEXP PNG_DLL_IMPORT
 #  endif

@@ -340,7 +340,7 @@
   * less efficient code.
   */
 #  if defined(__clang__) && defined(__has_attribute)
-   /* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
+     /* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
 #    if !defined(PNG_USE_RESULT) && __has_attribute(__warn_unused_result__)
 #      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
 #    endif
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,8 +1,8 @@

 /* pngerror.c - stub functions for i/o and memory allocation
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -26,7 +26,7 @@ static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
 #ifdef PNG_WARNINGS_SUPPORTED
 static void /* PRIVATE */
 png_default_warning PNGARG((png_const_structrp png_ptr,
-    png_const_charp warning_message));
+   png_const_charp warning_message));
 #endif /* WARNINGS */

 /* This function is called whenever there is a fatal error.  This function
@@ -37,14 +37,14 @@ png_default_warning PNGARG((png_const_structrp png_ptr,
 #ifdef PNG_ERROR_TEXT_SUPPORTED
 PNG_FUNCTION(void,PNGAPI
 png_error,(png_const_structrp png_ptr, png_const_charp error_message),
-    PNG_NORETURN)
+   PNG_NORETURN)
 {
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
   char msg[16];
   if (png_ptr != NULL)
   {
      if ((png_ptr->flags &
-         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
+         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0
      {
         if (*error_message == PNG_LITERAL_SHARP)
         {
@@ -65,18 +65,18 @@ png_error,(png_const_structrp png_ptr, png_const_charp error_message),

            else
               error_message += offset;
-         }
-
-         else
-         {
-            if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
-            {
-               msg[0] = '0';
-               msg[1] = '\0';
-               error_message = msg;
-            }
-         }
      }
+
+      else
+      {
+         if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
+         {
+            msg[0] = '0';
+            msg[1] = '\0';
+            error_message = msg;
+         }
+       }
+     }
   }
 #endif
   if (png_ptr != NULL && png_ptr->error_fn != NULL)
@@ -110,7 +110,7 @@ png_err,(png_const_structrp png_ptr),PNG_NORETURN)
 */
 size_t
 png_safecat(png_charp buffer, size_t bufsize, size_t pos,
-    png_const_charp string)
+   png_const_charp string)
 {
   if (buffer != NULL && pos < bufsize)
   {
@@ -131,7 +131,7 @@ png_safecat(png_charp buffer, size_t bufsize, size_t pos,
 */
 png_charp
 png_format_number(png_const_charp start, png_charp end, int format,
-    png_alloc_size_t number)
+   png_alloc_size_t number)
 {
   int count = 0;    /* number of digits output */
   int mincount = 1; /* minimum number required */
@@ -233,7 +233,7 @@ png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
   }
   if (png_ptr != NULL && png_ptr->warning_fn != NULL)
      (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
-          warning_message + offset);
+         warning_message + offset);
   else
      png_default_warning(png_ptr, warning_message + offset);
 }
@@ -245,7 +245,7 @@ png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 */
 void
 png_warning_parameter(png_warning_parameters p, int number,
-    png_const_charp string)
+   png_const_charp string)
 {
   if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
      (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
@@ -253,7 +253,7 @@ png_warning_parameter(png_warning_parameters p, int number,

 void
 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
-    png_alloc_size_t value)
+   png_alloc_size_t value)
 {
   char buffer[PNG_NUMBER_BUFFER_SIZE];
   png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
@@ -261,7 +261,7 @@ png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,

 void
 png_warning_parameter_signed(png_warning_parameters p, int number, int format,
-    png_int_32 value)
+   png_int_32 value)
 {
   png_alloc_size_t u;
   png_charp str;
@@ -282,7 +282,7 @@ png_warning_parameter_signed(png_warning_parameters p, int number, int format,

 void
 png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
-    png_const_charp message)
+   png_const_charp message)
 {
   /* The internal buffer is just 192 bytes - enough for all our messages,
    * overflow doesn't happen because this code checks!  If someone figures
@@ -391,10 +391,10 @@ png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
 void /* PRIVATE */
 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
 {
-   if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
-      png_warning(png_ptr, error_message);
-   else
-      png_error(png_ptr, error_message);
+  if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
+     png_warning(png_ptr, error_message);
+  else
+     png_error(png_ptr, error_message);

 #  ifndef PNG_ERROR_TEXT_SUPPORTED
      PNG_UNUSED(error_message)
@@ -404,10 +404,10 @@ png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
 void /* PRIVATE */
 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
 {
-   if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
-      png_warning(png_ptr, error_message);
-   else
-      png_error(png_ptr, error_message);
+  if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
+     png_warning(png_ptr, error_message);
+  else
+     png_error(png_ptr, error_message);

 #  ifndef PNG_ERROR_TEXT_SUPPORTED
      PNG_UNUSED(error_message)
@@ -478,7 +478,7 @@ png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
 PNG_FUNCTION(void,PNGAPI
 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
-    PNG_NORETURN)
+   PNG_NORETURN)
 {
   char msg[18+PNG_MAX_ERROR_TEXT];
   if (png_ptr == NULL)
@@ -620,7 +620,7 @@ png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
      else
      {
         png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
-             png_malloc_warn(png_ptr, jmp_buf_size));
+            png_malloc_warn(png_ptr, jmp_buf_size));

         if (png_ptr->jmp_buf_ptr == NULL)
            return NULL; /* new NULL return on OOM */
@@ -709,7 +709,7 @@ png_free_jmpbuf(png_structrp png_ptr)
 */
 static PNG_FUNCTION(void /* PRIVATE */,
 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
-    PNG_NORETURN)
+   PNG_NORETURN)
 {
 #ifdef PNG_CONSOLE_IO_SUPPORTED
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
@@ -883,7 +883,7 @@ png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
    */
 PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
 png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
-    PNG_NORETURN)
+   PNG_NORETURN)
 {
   const png_const_structrp png_ptr = png_nonconst_ptr;
   png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
@@ -906,7 +906,7 @@ png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
      /* Missing longjmp buffer, the following is to help debugging: */
      {
         size_t pos = png_safecat(image->message, (sizeof image->message), 0,
-             "bad longjmp: ");
+            "bad longjmp: ");
         png_safecat(image->message, (sizeof image->message), pos,
             error_message);
      }
--- a/pngget.c
+++ b/pngget.c
@@ -1,8 +1,8 @@

 /* pngget.c - retrieval of values from info struct
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -456,11 +456,11 @@ png_get_pHYs_dpi(png_const_structrp png_ptr, png_const_inforp info_ptr,
   return (retval);
 }
 #endif /* pHYs */
-#endif /* INCH_CONVERSIONS */
+#endif  /* INCH_CONVERSIONS */

 /* png_get_channels really belongs in here, too, but it's been around longer */

-#endif /* EASY_ACCESS */
+#endif  /* EASY_ACCESS */


 png_byte PNGAPI
@@ -486,7 +486,7 @@ png_get_signature(png_const_structrp png_ptr, png_const_inforp info_ptr)
 #ifdef PNG_bKGD_SUPPORTED
 png_uint_32 PNGAPI
 png_get_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
-    png_color_16p *background)
+   png_color_16p *background)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
       (info_ptr->valid & PNG_INFO_bKGD) != 0 &&
@@ -526,28 +526,28 @@ png_get_cHRM(png_const_structrp png_ptr, png_const_inforp info_ptr,

      if (white_x != NULL)
         *white_x = png_float(png_ptr,
-             info_ptr->colorspace.end_points_xy.whitex, "cHRM white X");
+            info_ptr->colorspace.end_points_xy.whitex, "cHRM white X");
      if (white_y != NULL)
         *white_y = png_float(png_ptr,
-             info_ptr->colorspace.end_points_xy.whitey, "cHRM white Y");
+            info_ptr->colorspace.end_points_xy.whitey, "cHRM white Y");
      if (red_x != NULL)
         *red_x = png_float(png_ptr, info_ptr->colorspace.end_points_xy.redx,
-             "cHRM red X");
+            "cHRM red X");
      if (red_y != NULL)
         *red_y = png_float(png_ptr, info_ptr->colorspace.end_points_xy.redy,
-             "cHRM red Y");
+            "cHRM red Y");
      if (green_x != NULL)
         *green_x = png_float(png_ptr,
-             info_ptr->colorspace.end_points_xy.greenx, "cHRM green X");
+            info_ptr->colorspace.end_points_xy.greenx, "cHRM green X");
      if (green_y != NULL)
         *green_y = png_float(png_ptr,
-             info_ptr->colorspace.end_points_xy.greeny, "cHRM green Y");
+            info_ptr->colorspace.end_points_xy.greeny, "cHRM green Y");
      if (blue_x != NULL)
         *blue_x = png_float(png_ptr, info_ptr->colorspace.end_points_xy.bluex,
-             "cHRM blue X");
+            "cHRM blue X");
      if (blue_y != NULL)
         *blue_y = png_float(png_ptr, info_ptr->colorspace.end_points_xy.bluey,
-             "cHRM blue Y");
+            "cHRM blue Y");
      return (PNG_INFO_cHRM);
   }

@@ -556,42 +556,42 @@ png_get_cHRM(png_const_structrp png_ptr, png_const_inforp info_ptr,

 png_uint_32 PNGAPI
 png_get_cHRM_XYZ(png_const_structrp png_ptr, png_const_inforp info_ptr,
-    double *red_X, double *red_Y, double *red_Z, double *green_X,
-    double *green_Y, double *green_Z, double *blue_X, double *blue_Y,
-    double *blue_Z)
+   double *red_X, double *red_Y, double *red_Z, double *green_X,
+   double *green_Y, double *green_Z, double *blue_X, double *blue_Y,
+   double *blue_Z)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      png_debug1(1, "in %s retrieval function", "cHRM_XYZ(float)");

      if (red_X != NULL)
         *red_X = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_X,
-             "cHRM red X");
+            "cHRM red X");
      if (red_Y != NULL)
         *red_Y = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_Y,
-             "cHRM red Y");
+            "cHRM red Y");
      if (red_Z != NULL)
         *red_Z = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_Z,
-             "cHRM red Z");
+            "cHRM red Z");
      if (green_X != NULL)
         *green_X = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.green_X, "cHRM green X");
+            info_ptr->colorspace.end_points_XYZ.green_X, "cHRM green X");
      if (green_Y != NULL)
         *green_Y = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.green_Y, "cHRM green Y");
+            info_ptr->colorspace.end_points_XYZ.green_Y, "cHRM green Y");
      if (green_Z != NULL)
         *green_Z = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.green_Z, "cHRM green Z");
+            info_ptr->colorspace.end_points_XYZ.green_Z, "cHRM green Z");
      if (blue_X != NULL)
         *blue_X = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.blue_X, "cHRM blue X");
+            info_ptr->colorspace.end_points_XYZ.blue_X, "cHRM blue X");
      if (blue_Y != NULL)
         *blue_Y = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.blue_Y, "cHRM blue Y");
+            info_ptr->colorspace.end_points_XYZ.blue_Y, "cHRM blue Y");
      if (blue_Z != NULL)
         *blue_Z = png_float(png_ptr,
-             info_ptr->colorspace.end_points_XYZ.blue_Z, "cHRM blue Z");
+            info_ptr->colorspace.end_points_XYZ.blue_Z, "cHRM blue Z");
      return (PNG_INFO_cHRM);
   }

@@ -681,8 +681,8 @@ png_get_gAMA_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
   png_debug1(1, "in %s retrieval function", "gAMA");

   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
-       file_gamma != NULL)
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+      file_gamma != NULL)
   {
      *file_gamma = info_ptr->colorspace.gamma;
      return (PNG_INFO_gAMA);
@@ -704,7 +704,7 @@ png_get_gAMA(png_const_structrp png_ptr, png_const_inforp info_ptr,
      file_gamma != NULL)
   {
      *file_gamma = png_float(png_ptr, info_ptr->colorspace.gamma,
-          "png_get_gAMA");
+         "png_get_gAMA");
      return (PNG_INFO_gAMA);
   }

@@ -901,7 +901,7 @@ png_get_sCAL_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
       */
      *width = png_fixed(png_ptr, atof(info_ptr->scal_s_width), "sCAL width");
      *height = png_fixed(png_ptr, atof(info_ptr->scal_s_height),
-          "sCAL height");
+         "sCAL height");
      return (PNG_INFO_sCAL);
   }

@@ -1142,19 +1142,19 @@ png_get_compression_buffer_size(png_const_structrp png_ptr)
      return 0;

 #ifdef PNG_WRITE_SUPPORTED
-   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
 #endif
   {
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-      return png_ptr->IDAT_read_size;
+         return png_ptr->IDAT_read_size;
 #else
-      return PNG_IDAT_READ_SIZE;
+         return PNG_IDAT_READ_SIZE;
 #endif
   }

 #ifdef PNG_WRITE_SUPPORTED
-   else
-      return png_ptr->zbuffer_size;
+      else
+         return png_ptr->zbuffer_size;
 #endif
 }

--- a/pngmem.c
+++ b/pngmem.c
@@ -1,8 +1,8 @@

 /* pngmem.c - stub functions for memory allocation
 *
- * Last changed in libpng 1.6.24 [August 4, 2016%]
- * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -66,7 +66,7 @@ png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 */
 PNG_FUNCTION(png_voidp /* PRIVATE */,
 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
-    PNG_ALLOCATED)
+   PNG_ALLOCATED)
 {
   /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
    * allocators have also been removed in 1.6.0, so any 16-bit system now has
@@ -107,7 +107,7 @@ png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
 */
 static png_voidp
 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
-    size_t element_size)
+   size_t element_size)
 {
   png_alloc_size_t req = nelements; /* known to be > 0 */

@@ -120,7 +120,7 @@ png_malloc_array_checked(png_const_structrp png_ptr, int nelements,

 PNG_FUNCTION(png_voidp /* PRIVATE */,
 png_malloc_array,(png_const_structrp png_ptr, int nelements,
-    size_t element_size),PNG_ALLOCATED)
+   size_t element_size),PNG_ALLOCATED)
 {
   if (nelements <= 0 || element_size == 0)
      png_error(png_ptr, "internal error: array alloc");
@@ -130,7 +130,7 @@ png_malloc_array,(png_const_structrp png_ptr, int nelements,

 PNG_FUNCTION(png_voidp /* PRIVATE */,
 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
-    int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
+   int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
 {
   /* These are internal errors: */
   if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
@@ -143,7 +143,7 @@ png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
   if (add_elements <= INT_MAX - old_elements)
   {
      png_voidp new_array = png_malloc_array_checked(png_ptr,
-          old_elements+add_elements, element_size);
+         old_elements+add_elements, element_size);

      if (new_array != NULL)
      {
@@ -154,7 +154,7 @@ png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
            memcpy(new_array, old_array, element_size*(unsigned)old_elements);

         memset((char*)new_array + element_size*(unsigned)old_elements, 0,
-             element_size*(unsigned)add_elements);
+            element_size*(unsigned)add_elements);

         return new_array;
      }
@@ -187,7 +187,7 @@ png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 #ifdef PNG_USER_MEM_SUPPORTED
 PNG_FUNCTION(png_voidp,PNGAPI
 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
-    PNG_ALLOCATED PNG_DEPRECATED)
+   PNG_ALLOCATED PNG_DEPRECATED)
 {
   png_voidp ret;

@@ -210,7 +210,7 @@ png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
 */
 PNG_FUNCTION(png_voidp,PNGAPI
 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
-    PNG_ALLOCATED)
+   PNG_ALLOCATED)
 {
   if (png_ptr != NULL)
   {
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,8 +1,8 @@

 /* pngpread.c - read a png file in push mode
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -77,11 +77,11 @@ png_process_data_pause(png_structrp png_ptr, int save)
 png_uint_32 PNGAPI
 png_process_data_skip(png_structrp png_ptr)
 {
-/* TODO: Deprecate and remove this API.
- * Somewhere the implementation of this seems to have been lost,
- * or abandoned.  It was only to support some internal back-door access
- * to png_struct) in libpng-1.4.x.
- */
+  /* TODO: Deprecate and remove this API.
+   * Somewhere the implementation of this seems to have been lost,
+   * or abandoned.  It was only to support some internal back-door access
+   * to png_struct) in libpng-1.4.x.
+   */
   png_app_warning(png_ptr,
 "png_process_data_skip is not implemented in any current version of libpng");
   return 0;
@@ -210,14 +210,12 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
          (png_ptr->mode & PNG_HAVE_PLTE) == 0)
         png_error(png_ptr, "Missing PLTE before IDAT");

+      png_ptr->mode |= PNG_HAVE_IDAT;
      png_ptr->process_mode = PNG_READ_IDAT_MODE;

-      if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
-         if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
-            if (png_ptr->push_length == 0)
-               return;
-
-      png_ptr->mode |= PNG_HAVE_IDAT;
+      if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
+         if (png_ptr->push_length == 0)
+            return;

      if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
         png_benign_error(png_ptr, "Too many IDATs found");
@@ -410,7 +408,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
   {
      PNG_PUSH_SAVE_BUFFER_IF_FULL
      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
-          PNG_HANDLE_CHUNK_AS_DEFAULT);
+         PNG_HANDLE_CHUNK_AS_DEFAULT);
   }

   png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
@@ -501,10 +499,7 @@ png_push_save_buffer(png_structrp png_ptr)
         png_error(png_ptr, "Insufficient memory for save_buffer");
      }

-      if (old_buffer)
-         memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
-      else if (png_ptr->save_buffer_size)
-         png_error(png_ptr, "save_buffer error");
+      memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
      png_free(png_ptr, old_buffer);
      png_ptr->save_buffer_max = new_max;
   }
@@ -521,7 +516,7 @@ png_push_save_buffer(png_structrp png_ptr)

 void /* PRIVATE */
 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
-    png_size_t buffer_length)
+   png_size_t buffer_length)
 {
   png_ptr->current_buffer = buffer;
   png_ptr->current_buffer_size = buffer_length;
@@ -624,7 +619,7 @@ png_push_read_IDAT(png_structrp png_ptr)

 void /* PRIVATE */
 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
-    png_size_t buffer_length)
+   png_size_t buffer_length)
 {
   /* The caller checks for a non-zero buffer length. */
   if (!(buffer_length > 0) || buffer == NULL)
@@ -782,7 +777,7 @@ png_push_process_row(png_structrp png_ptr)
   {
      if (png_ptr->pass < 6)
         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
-             png_ptr->transformations);
+            png_ptr->transformations);

      switch (png_ptr->pass)
      {
@@ -1044,7 +1039,7 @@ png_push_have_row(png_structrp png_ptr, png_bytep row)
 {
   if (png_ptr->row_fn != NULL)
      (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
-          (int)png_ptr->pass);
+         (int)png_ptr->pass);
 }

 #ifdef PNG_READ_INTERLACING_SUPPORTED
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,8 +1,8 @@

 /* pngpriv.h - private declarations for use inside libpng
 *
- * Last changed in libpng 1.6.25 [September 1, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.21 [January 15, 2016]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -182,35 +182,6 @@
 #  endif
 #endif /* PNG_ARM_NEON_OPT > 0 */

-#ifndef PNG_MIPS_MSA_OPT
-#  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
-#     define PNG_MIPS_MSA_OPT 2
-#  else
-#     define PNG_MIPS_MSA_OPT 0
-#  endif
-#endif
-
-#if PNG_MIPS_MSA_OPT > 0
-#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
-#  ifndef PNG_MIPS_MSA_IMPLEMENTATION
-#     if defined(__mips_msa)
-#        if defined(__clang__)
-#        elif defined(__GNUC__)
-#           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
-#              define PNG_MIPS_MSA_IMPLEMENTATION 2
-#           endif /* no GNUC support */
-#        endif /* __GNUC__ */
-#     else /* !defined __mips_msa */
-#        define PNG_MIPS_MSA_IMPLEMENTATION 2
-#     endif /* __mips_msa */
-#  endif /* !PNG_MIPS_MSA_IMPLEMENTATION */
-
-#  ifndef PNG_MIPS_MSA_IMPLEMENTATION
-#     define PNG_MIPS_MSA_IMPLEMENTATION 1
-#  endif
-#endif /* PNG_MIPS_MSA_OPT > 0 */
-
-
 /* Is this a build of a DLL where compilation of the object modules requires
 * different preprocessor settings to those required for a simple library?  If
 * so PNG_BUILD_DLL must be set.
@@ -449,10 +420,10 @@

 #  if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
    defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
-   /* We need to check that <math.h> hasn't already been included earlier
-    * as it seems it doesn't agree with <fp.h>, yet we should really use
-    * <fp.h> if possible.
-    */
+     /* We need to check that <math.h> hasn't already been included earlier
+      * as it seems it doesn't agree with <fp.h>, yet we should really use
+      * <fp.h> if possible.
+      */
 #    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
 #      include <fp.h>
 #    endif
@@ -460,9 +431,9 @@
 #    include <math.h>
 #  endif
 #  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
-   /* Amiga SAS/C: We must include builtin FPU functions when compiling using
-    * MATH=68881
-    */
+     /* Amiga SAS/C: We must include builtin FPU functions when compiling using
+      * MATH=68881
+      */
 #    include <m68881.h>
 #  endif
 #endif
@@ -1054,7 +1025,7 @@ PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
 #ifdef PNG_WRITE_cHRM_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
    const png_xy *xy), PNG_EMPTY);
-   /* The xy value must have been previously validated */
+    /* The xy value must have been previously validated */
 #endif

 #ifdef PNG_WRITE_sRGB_SUPPORTED
@@ -1203,7 +1174,6 @@ PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);

-#if PNG_ARM_NEON_OPT > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
@@ -1218,24 +1188,6 @@ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-#endif
-
-#if PNG_MIPS_MSA_OPT > 0
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_msa,(png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-#endif

 /* Choose the best filter to use and filter the row data */
 PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
@@ -1461,7 +1413,7 @@ PNG_INTERNAL_FUNCTION(void,png_push_have_info,(png_structrp png_ptr,
 PNG_INTERNAL_FUNCTION(void,png_push_have_end,(png_structrp png_ptr,
   png_inforp info_ptr),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_have_row,(png_structrp png_ptr,
-    png_bytep row),PNG_EMPTY);
+     png_bytep row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_read_end,(png_structrp png_ptr,
    png_inforp info_ptr),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_process_some_data,(png_structrp png_ptr,
@@ -1500,13 +1452,13 @@ PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,

 PNG_INTERNAL_FUNCTION(void,png_colorspace_sync_info,(png_const_structrp png_ptr,
    png_inforp info_ptr), PNG_EMPTY);
-   /* Synchronize the info 'valid' flags with the colorspace */
+    /* Synchronize the info 'valid' flags with the colorspace */

 PNG_INTERNAL_FUNCTION(void,png_colorspace_sync,(png_const_structrp png_ptr,
    png_inforp info_ptr), PNG_EMPTY);
-   /* Copy the png_struct colorspace to the info_struct and call the above to
-    * synchronize the flags.  Checks for NULL info_ptr and does nothing.
-    */
+    /* Copy the png_struct colorspace to the info_struct and call the above to
+     * synchronize the flags.  Checks for NULL info_ptr and does nothing.
+     */
 #endif

 /* Added at libpng version 1.4.0 */
@@ -1540,11 +1492,9 @@ PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
   /* The 'name' is used for information only */

 /* Routines for checking parts of an ICC profile. */
-#ifdef PNG_READ_iCCP_SUPPORTED
 PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length), PNG_EMPTY);
-#endif /* READ_iCCP */
 PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length,
@@ -1963,17 +1913,10 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
    */
-#  if PNG_ARM_NEON_OPT > 0
 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif

-#if PNG_MIPS_MSA_OPT > 0
-PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
-   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
-#endif
-#endif
-
 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
   png_const_charp key, png_bytep new_key), PNG_EMPTY);

--- a/pngread.c
+++ b/pngread.c
@@ -1,8 +1,8 @@

 /* pngread.c - read a PNG file
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -28,10 +28,10 @@ png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
 {
 #ifndef PNG_USER_MEM_SUPPORTED
   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
-        error_fn, warn_fn, NULL, NULL, NULL);
+      error_fn, warn_fn, NULL, NULL, NULL);
 #else
   return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
-        warn_fn, NULL, NULL, NULL);
+       warn_fn, NULL, NULL, NULL);
 }

 /* Alternate create PNG structure for reading, and allocate any memory
@@ -43,7 +43,7 @@ png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
    png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
 {
   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
-       error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
+      error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
 #endif /* USER_MEM */

   if (png_ptr != NULL)
@@ -127,10 +127,7 @@ png_read_info(png_structrp png_ptr, png_inforp info_ptr)
      }

      else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
-      {
-         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
         png_ptr->mode |= PNG_AFTER_IDAT;
-      }

      /* This should be a binary subdivision search or a hash for
       * matching the chunk name rather than a linear search.
@@ -252,7 +249,7 @@ png_read_info(png_structrp png_ptr, png_inforp info_ptr)

      else
         png_handle_unknown(png_ptr, info_ptr, length,
-             PNG_HANDLE_CHUNK_AS_DEFAULT);
+            PNG_HANDLE_CHUNK_AS_DEFAULT);
   }
 }
 #endif /* SEQUENTIAL_READ */
@@ -279,7 +276,7 @@ png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
      else
         png_app_error(png_ptr,
-             "png_read_update_info/png_start_read_image: duplicate call");
+            "png_read_update_info/png_start_read_image: duplicate call");
   }
 }

@@ -302,7 +299,7 @@ png_start_read_image(png_structrp png_ptr)
      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
      else
         png_app_error(png_ptr,
-             "png_start_read_image/png_read_update_info: duplicate call");
+            "png_start_read_image/png_read_update_info: duplicate call");
   }
 }
 #endif /* SEQUENTIAL_READ */
@@ -540,7 +537,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   {
      if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
         png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
-             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
+            png_ptr->prev_row + 1, png_ptr->row_buf[0]);
      else
         png_error(png_ptr, "bad adaptive filter value");
   }
@@ -584,7 +581,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   {
      if (png_ptr->pass < 6)
         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
-             png_ptr->transformations);
+            png_ptr->transformations);

      if (dsp_row != NULL)
         png_combine_row(png_ptr, dsp_row, 1/*display*/);
@@ -719,7 +716,7 @@ png_read_image(png_structrp png_ptr, png_bytepp image)
          * but the caller should do it!
          */
         png_warning(png_ptr, "Interlace handling should be turned on when "
-             "using png_read_image");
+            "using png_read_image");
         /* Make sure this is set correctly */
         png_ptr->num_rows = png_ptr->height;
      }
@@ -779,8 +776,8 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
   /* Report invalid palette index; added at libng-1.5.10 */
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-       png_ptr->num_palette_max > png_ptr->num_palette)
-      png_benign_error(png_ptr, "Read palette index exceeding num_palette");
+      png_ptr->num_palette_max > png_ptr->num_palette)
+     png_benign_error(png_ptr, "Read palette index exceeding num_palette");
 #endif

   do
@@ -788,9 +785,6 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
      png_uint_32 length = png_read_chunk_header(png_ptr);
      png_uint_32 chunk_name = png_ptr->chunk_name;

-      if (chunk_name != png_IDAT)
-         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
-
      if (chunk_name == png_IEND)
         png_handle_IEND(png_ptr, info_ptr, length);

@@ -805,9 +799,9 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
      {
         if (chunk_name == png_IDAT)
         {
-            if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
-                || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
-               png_benign_error(png_ptr, ".Too many IDATs found");
+            if ((length > 0) ||
+                (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
+               png_benign_error(png_ptr, "Too many IDATs found");
         }
         png_handle_unknown(png_ptr, info_ptr, length, keep);
         if (chunk_name == png_PLTE)
@@ -818,14 +812,10 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
      else if (chunk_name == png_IDAT)
      {
         /* Zero length IDATs are legal after the last IDAT has been
-          * read, but not after other chunks have been read.  1.6 does not
-          * always read all the deflate data; specifically it cannot be relied
-          * upon to read the Adler32 at the end.  If it doesn't ignore IDAT
-          * chunks which are longer than zero as well:
+          * read, but not after other chunks have been read.
          */
-         if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
-             || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
-            png_benign_error(png_ptr, "..Too many IDATs found");
+         if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
+            png_benign_error(png_ptr, "Too many IDATs found");

         png_crc_finish(png_ptr, length);
      }
@@ -919,7 +909,7 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)

      else
         png_handle_unknown(png_ptr, info_ptr, length,
-             PNG_HANDLE_CHUNK_AS_DEFAULT);
+            PNG_HANDLE_CHUNK_AS_DEFAULT);
   } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
 }
 #endif /* SEQUENTIAL_READ */
@@ -1030,7 +1020,8 @@ png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
-    int transforms, voidp params)
+                           int transforms,
+                           voidp params)
 {
   if (png_ptr == NULL || info_ptr == NULL)
      return;
@@ -1306,7 +1297,7 @@ png_image_read_init(png_imagep image)
         if (info_ptr != NULL)
         {
            png_controlp control = png_voidcast(png_controlp,
-                png_malloc_warn(png_ptr, (sizeof *control)));
+               png_malloc_warn(png_ptr, (sizeof *control)));

            if (control != NULL)
            {
@@ -1469,12 +1460,12 @@ png_image_begin_read_from_stdio(png_imagep image, FILE* file)

      else
         return png_image_error(image,
-             "png_image_begin_read_from_stdio: invalid argument");
+            "png_image_begin_read_from_stdio: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
+         "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");

   return 0;
 }
@@ -1507,12 +1498,12 @@ png_image_begin_read_from_file(png_imagep image, const char *file_name)

      else
         return png_image_error(image,
-             "png_image_begin_read_from_file: invalid argument");
+            "png_image_begin_read_from_file: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
+         "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");

   return 0;
 }
@@ -1549,7 +1540,7 @@ png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
 }

 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
-    png_const_voidp memory, png_size_t size)
+   png_const_voidp memory, png_size_t size)
 {
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
@@ -1572,12 +1563,12 @@ int PNGAPI png_image_begin_read_from_memory(png_imagep image,

      else
         return png_image_error(image,
-             "png_image_begin_read_from_memory: invalid argument");
+            "png_image_begin_read_from_memory: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
+         "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");

   return 0;
 }
@@ -1623,12 +1614,12 @@ png_image_skip_unused_chunks(png_structrp png_ptr)
        * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
        */
       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
-           NULL, -1);
+         NULL, -1);

       /* But do not ignore image data handling chunks */
       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
-           chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
-   }
+         chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
+    }
 }

 #  define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
@@ -1695,7 +1686,7 @@ decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
 #ifdef __GNUC__
      default:
         png_error(display->image->opaque->png_ptr,
-             "unexpected encoding (internal error)");
+            "unexpected encoding (internal error)");
 #endif
   }

@@ -1704,8 +1695,8 @@ decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)

 static png_uint_32
 png_colormap_compose(png_image_read_control *display,
-    png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
-    png_uint_32 background, int encoding)
+   png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
+   png_uint_32 background, int encoding)
 {
   /* The file value is composed on the background, the background has the given
    * encoding and so does the result, the file is encoded with P_FILE and the
@@ -1741,14 +1732,14 @@ png_colormap_compose(png_image_read_control *display,
 */
 static void
 png_create_colormap_entry(png_image_read_control *display,
-    png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
-    png_uint_32 alpha, int encoding)
+   png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
+   png_uint_32 alpha, int encoding)
 {
   png_imagep image = display->image;
   const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
-       P_LINEAR : P_sRGB;
+      P_LINEAR : P_sRGB;
   const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
-       (red != green || green != blue);
+      (red != green || green != blue);

   if (ip > 255)
      png_error(image->opaque->png_ptr, "color-map index out of range");
@@ -2028,7 +2019,7 @@ make_ga_colormap(png_image_read_control *display)

      for (g=0; g<6; ++g)
         png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
-             P_sRGB);
+            P_sRGB);
   }

   return i;
@@ -2052,7 +2043,7 @@ make_rgb_colormap(png_image_read_control *display)

         for (b=0; b<6; ++b)
            png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
-                P_sRGB);
+               P_sRGB);
      }
   }

@@ -2104,7 +2095,7 @@ png_image_read_colormap(png_voidp argument)

      else if (display->background == NULL /* no way to remove it */)
         png_error(png_ptr,
-             "background color must be supplied to remove alpha/transparency");
+            "a background color must be supplied to remove alpha/transparency");

      /* Get a copy of the background color (this avoids repeating the checks
       * below.)  The encoding is 8-bit sRGB or 16-bit linear, depending on the
@@ -2199,7 +2190,7 @@ png_image_read_colormap(png_voidp argument)
                */
               if (i != trans)
                  png_create_colormap_entry(display, i, val, val, val, 255,
-                      P_FILE/*8-bit with file gamma*/);
+                     P_FILE/*8-bit with file gamma*/);

               /* Else this entry is transparent.  The colors don't matter if
                * there is an alpha channel (back_alpha == 0), but it does no
@@ -2211,7 +2202,7 @@ png_image_read_colormap(png_voidp argument)
                */
               else
                  png_create_colormap_entry(display, i, back_r, back_g, back_b,
-                      back_alpha, output_encoding);
+                     back_alpha, output_encoding);
            }

            /* We need libpng to preserve the original encoding. */
@@ -2276,7 +2267,7 @@ png_image_read_colormap(png_voidp argument)
                         * matches.
                         */
                        png_create_colormap_entry(display, gray, back_g, back_g,
-                            back_g, 65535, P_LINEAR);
+                           back_g, 65535, P_LINEAR);
                     }

                     /* The background passed to libpng, however, must be the
@@ -2290,8 +2281,8 @@ png_image_read_colormap(png_voidp argument)
                      * doesn't.
                      */
                     png_set_background_fixed(png_ptr, &c,
-                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
-                         0/*gamma: not used*/);
+                        PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                        0/*gamma: not used*/);

                     output_processing = PNG_CMAP_NONE;
                     break;
@@ -2321,7 +2312,7 @@ png_image_read_colormap(png_voidp argument)
                * background color at full precision.
                */
               png_create_colormap_entry(display, 254, back_r, back_g, back_b,
-                   back_alpha, output_encoding);
+                  back_alpha, output_encoding);
            }

            else
@@ -2389,7 +2380,7 @@ png_image_read_colormap(png_voidp argument)

                  /* And make sure the corresponding palette entry matches. */
                  png_create_colormap_entry(display, gray, back_g, back_g,
-                      back_g, 65535, P_LINEAR);
+                     back_g, 65535, P_LINEAR);
               }

               /* The background passed to libpng, however, must be the sRGB
@@ -2399,8 +2390,8 @@ png_image_read_colormap(png_voidp argument)
               c.gray = c.red = c.green = c.blue = (png_uint_16)gray;

               png_set_background_fixed(png_ptr, &c,
-                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
-                   0/*gamma: not used*/);
+                  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                  0/*gamma: not used*/);

               output_processing = PNG_CMAP_NONE;
            }
@@ -2420,7 +2411,7 @@ png_image_read_colormap(png_voidp argument)
               {
                  png_uint_32 gray = (i * 256 + 115) / 231;
                  png_create_colormap_entry(display, i++, gray, gray, gray,
-                      255, P_sRGB);
+                     255, P_sRGB);
               }

               /* NOTE: this preserves the full precision of the application
@@ -2429,13 +2420,13 @@ png_image_read_colormap(png_voidp argument)
               background_index = i;
               png_create_colormap_entry(display, i++, back_r, back_g, back_b,
 #ifdef __COVERITY__
-                   /* Coverity claims that output_encoding
-                    * cannot be 2 (P_LINEAR) here.
-                    */ 255U,
+                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                  * here.
+                  */ 255U,
 #else
-                    output_encoding == P_LINEAR ? 65535U : 255U,
+                  output_encoding == P_LINEAR ? 65535U : 255U,
 #endif
-                    output_encoding);
+                  output_encoding);

               /* For non-opaque input composite on the sRGB background - this
                * requires inverting the encoding for each component.  The input
@@ -2473,9 +2464,9 @@ png_image_read_colormap(png_voidp argument)
                     png_uint_32 gray = png_sRGB_table[g*51] * alpha;

                     png_create_colormap_entry(display, i++,
-                         PNG_sRGB_FROM_LINEAR(gray + back_rx),
-                         PNG_sRGB_FROM_LINEAR(gray + back_gx),
-                         PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
+                        PNG_sRGB_FROM_LINEAR(gray + back_rx),
+                        PNG_sRGB_FROM_LINEAR(gray + back_gx),
+                        PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
                  }
               }

@@ -2501,7 +2492,7 @@ png_image_read_colormap(png_voidp argument)
             * png_set_tRNS_to_alpha before png_set_background_fixed.
             */
            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
-                -1);
+               -1);
            data_encoding = P_sRGB;

            /* The output will now be one or two 8-bit gray or gray+alpha
@@ -2577,13 +2568,13 @@ png_image_read_colormap(png_voidp argument)
                        gray = png_sRGB_table[gray]; /* now P_LINEAR */

                     gray = PNG_DIV257(png_gamma_16bit_correct(gray,
-                         png_ptr->colorspace.gamma)); /* now P_FILE */
+                        png_ptr->colorspace.gamma)); /* now P_FILE */

                     /* And make sure the corresponding palette entry contains
                      * exactly the required sRGB value.
                      */
                     png_create_colormap_entry(display, gray, back_g, back_g,
-                         back_g, 0/*unused*/, output_encoding);
+                        back_g, 0/*unused*/, output_encoding);
                  }

                  else if (output_encoding == P_LINEAR)
@@ -2608,8 +2599,8 @@ png_image_read_colormap(png_voidp argument)
                   */
                  expand_tRNS = 1;
                  png_set_background_fixed(png_ptr, &c,
-                      PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
-                      0/*gamma: not used*/);
+                     PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                     0/*gamma: not used*/);
               }

               output_processing = PNG_CMAP_NONE;
@@ -2643,7 +2634,7 @@ png_image_read_colormap(png_voidp argument)

                  /* Add a transparent entry. */
                  png_create_colormap_entry(display, cmap_entries, 255, 255,
-                      255, 0, P_sRGB);
+                     255, 0, P_sRGB);

                  /* This is stored as the background index for the processing
                   * algorithm.
@@ -2664,7 +2655,7 @@ png_image_read_colormap(png_voidp argument)
                         */
                        for (b=0; b<256; b = (b << 1) | 0x7f)
                           png_create_colormap_entry(display, cmap_entries++,
-                               r, g, b, 128, P_sRGB);
+                              r, g, b, 128, P_sRGB);
                     }
                  }

@@ -2691,7 +2682,7 @@ png_image_read_colormap(png_voidp argument)
                  cmap_entries = make_rgb_colormap(display);

                  png_create_colormap_entry(display, cmap_entries, back_r,
-                      back_g, back_b, 0/*unused*/, output_encoding);
+                        back_g, back_b, 0/*unused*/, output_encoding);

                  if (output_encoding == P_LINEAR)
                  {
@@ -2713,9 +2704,9 @@ png_image_read_colormap(png_voidp argument)
                   * index.
                   */
                  if (memcmp((png_const_bytep)display->colormap +
-                      sample_size * cmap_entries,
-                      (png_const_bytep)display->colormap +
-                          sample_size * PNG_RGB_INDEX(r,g,b),
+                        sample_size * cmap_entries,
+                     (png_const_bytep)display->colormap +
+                        sample_size * PNG_RGB_INDEX(r,g,b),
                     sample_size) != 0)
                  {
                     /* The background color must be added. */
@@ -2733,13 +2724,13 @@ png_image_read_colormap(png_voidp argument)
                            */
                           for (b=0; b<256; b = (b << 1) | 0x7f)
                              png_create_colormap_entry(display, cmap_entries++,
-                                  png_colormap_compose(display, r, P_sRGB, 128,
-                                      back_r, output_encoding),
-                                  png_colormap_compose(display, g, P_sRGB, 128,
-                                      back_g, output_encoding),
-                                  png_colormap_compose(display, b, P_sRGB, 128,
-                                      back_b, output_encoding),
-                                  0/*unused*/, output_encoding);
+                                 png_colormap_compose(display, r, P_sRGB, 128,
+                                    back_r, output_encoding),
+                                 png_colormap_compose(display, g, P_sRGB, 128,
+                                    back_g, output_encoding),
+                                 png_colormap_compose(display, b, P_sRGB, 128,
+                                    back_b, output_encoding),
+                                 0/*unused*/, output_encoding);
                        }
                     }

@@ -2757,8 +2748,8 @@ png_image_read_colormap(png_voidp argument)
                     c.blue = (png_uint_16)back_b;

                     png_set_background_fixed(png_ptr, &c,
-                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
-                         0/*gamma: not used*/);
+                        PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                        0/*gamma: not used*/);

                     output_processing = PNG_CMAP_RGB;
                  }
@@ -2810,7 +2801,7 @@ png_image_read_colormap(png_voidp argument)
               {
                  if (trans[i] == 0)
                     png_create_colormap_entry(display, i, back_r, back_g,
-                         back_b, 0, output_encoding);
+                        back_b, 0, output_encoding);

                  else
                  {
@@ -2818,22 +2809,22 @@ png_image_read_colormap(png_voidp argument)
                      * on the sRGB color in 'back'.
                      */
                     png_create_colormap_entry(display, i,
-                         png_colormap_compose(display, colormap[i].red,
-                             P_FILE, trans[i], back_r, output_encoding),
-                         png_colormap_compose(display, colormap[i].green,
-                             P_FILE, trans[i], back_g, output_encoding),
-                         png_colormap_compose(display, colormap[i].blue,
-                             P_FILE, trans[i], back_b, output_encoding),
-                         output_encoding == P_LINEAR ? trans[i] * 257U :
-                             trans[i],
-                         output_encoding);
+                        png_colormap_compose(display, colormap[i].red, P_FILE,
+                           trans[i], back_r, output_encoding),
+                        png_colormap_compose(display, colormap[i].green, P_FILE,
+                           trans[i], back_g, output_encoding),
+                        png_colormap_compose(display, colormap[i].blue, P_FILE,
+                           trans[i], back_b, output_encoding),
+                        output_encoding == P_LINEAR ? trans[i] * 257U :
+                           trans[i],
+                        output_encoding);
                  }
               }

               else
                  png_create_colormap_entry(display, i, colormap[i].red,
-                      colormap[i].green, colormap[i].blue,
-                      i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
+                     colormap[i].green, colormap[i].blue,
+                     i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
            }

            /* The PNG data may have indices packed in fewer than 8 bits, it
@@ -2923,7 +2914,7 @@ static int
 png_image_read_and_map(png_voidp argument)
 {
   png_image_read_control *display = png_voidcast(png_image_read_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_structrp png_ptr = image->opaque->png_ptr;
   int passes;
@@ -3060,7 +3051,7 @@ png_image_read_and_map(png_voidp argument)

                     if (alpha >= 196)
                        *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
-                            inrow[2]);
+                           inrow[2]);

                     else if (alpha < 64)
                        *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
@@ -3112,7 +3103,7 @@ static int
 png_image_read_colormapped(png_voidp argument)
 {
   png_image_read_control *display = png_voidcast(png_image_read_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_controlp control = image->opaque;
   png_structrp png_ptr = control->png_ptr;
@@ -3245,7 +3236,7 @@ static int
 png_image_read_composite(png_voidp argument)
 {
   png_image_read_control *display = png_voidcast(png_image_read_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_structrp png_ptr = image->opaque->png_ptr;
   int passes;
@@ -3372,7 +3363,7 @@ static int
 png_image_read_background(png_voidp argument)
 {
   png_image_read_control *display = png_voidcast(png_image_read_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_structrp png_ptr = image->opaque->png_ptr;
   png_inforp info_ptr = image->opaque->info_ptr;
@@ -3432,7 +3423,8 @@ png_image_read_background(png_voidp argument)

            for (pass = 0; pass < passes; ++pass)
            {
-               png_bytep row = png_voidcast(png_bytep, display->first_row);
+               png_bytep        row = png_voidcast(png_bytep,
+                                                   display->first_row);
               unsigned int     startx, stepx, stepy;
               png_uint_32      y;

@@ -3460,7 +3452,7 @@ png_image_read_background(png_voidp argument)
                  for (; y<height; y += stepy)
                  {
                     png_bytep inrow = png_voidcast(png_bytep,
-                         display->local_row);
+                        display->local_row);
                     png_bytep outrow = first_row + y * step_row;
                     png_const_bytep end_row = outrow + width;

@@ -3505,7 +3497,7 @@ png_image_read_background(png_voidp argument)
                  for (; y<height; y += stepy)
                  {
                     png_bytep inrow = png_voidcast(png_bytep,
-                         display->local_row);
+                        display->local_row);
                     png_bytep outrow = first_row + y * step_row;
                     png_const_bytep end_row = outrow + width;

@@ -3552,7 +3544,7 @@ png_image_read_background(png_voidp argument)
          */
         {
            png_uint_16p first_row = png_voidcast(png_uint_16p,
-                display->first_row);
+               display->first_row);
            /* The division by two is safe because the caller passed in a
             * stride which was multiplied by 2 (below) to get row_bytes.
             */
@@ -3602,7 +3594,7 @@ png_image_read_background(png_voidp argument)

                  /* Read the row, which is packed: */
                  png_read_row(png_ptr, png_voidcast(png_bytep,
-                      display->local_row), NULL);
+                     display->local_row), NULL);
                  inrow = png_voidcast(png_const_uint_16p, display->local_row);

                  /* Now do the pre-multiplication on each pixel in this row.
@@ -3651,7 +3643,7 @@ static int
 png_image_read_direct(png_voidp argument)
 {
   png_image_read_control *display = png_voidcast(png_image_read_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_structrp png_ptr = image->opaque->png_ptr;
   png_inforp info_ptr = image->opaque->info_ptr;
@@ -3702,7 +3694,7 @@ png_image_read_direct(png_voidp argument)
               do_local_background = 1/*maybe*/;

            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
-                PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
+               PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
         }

         change &= ~PNG_FORMAT_FLAG_COLOR;
@@ -3761,7 +3753,7 @@ png_image_read_direct(png_voidp argument)
          * final value.
          */
         if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
-             PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
+               PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
            do_local_background = 0;

         else if (mode == PNG_ALPHA_STANDARD)
@@ -3824,8 +3816,8 @@ png_image_read_direct(png_voidp argument)
                * pixels.
                */
               png_set_background_fixed(png_ptr, &c,
-                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
-                   0/*gamma: not used*/);
+                  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                  0/*gamma: not used*/);
            }

            else /* compose on row: implemented below. */
@@ -3856,16 +3848,16 @@ png_image_read_direct(png_voidp argument)
            else
               filler = 255;

-#ifdef PNG_FORMAT_AFIRST_SUPPORTED
-            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
-            {
-               where = PNG_FILLER_BEFORE;
-               change &= ~PNG_FORMAT_FLAG_AFIRST;
-            }
+#           ifdef PNG_FORMAT_AFIRST_SUPPORTED
+               if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
+               {
+                  where = PNG_FILLER_BEFORE;
+                  change &= ~PNG_FORMAT_FLAG_AFIRST;
+               }

-            else
-#endif
-            where = PNG_FILLER_AFTER;
+               else
+#           endif
+               where = PNG_FILLER_AFTER;

            png_set_add_alpha(png_ptr, filler, where);
         }
@@ -3973,12 +3965,12 @@ png_image_read_direct(png_voidp argument)
      if (info_ptr->bit_depth == 16)
         info_format |= PNG_FORMAT_FLAG_LINEAR;

-#ifdef PNG_FORMAT_BGR_SUPPORTED
-      if ((png_ptr->transformations & PNG_BGR) != 0)
-         info_format |= PNG_FORMAT_FLAG_BGR;
-#endif
+#     ifdef PNG_FORMAT_BGR_SUPPORTED
+         if ((png_ptr->transformations & PNG_BGR) != 0)
+            info_format |= PNG_FORMAT_FLAG_BGR;
+#     endif

-#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
         if (do_local_background == 2)
         {
            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
@@ -4075,117 +4067,67 @@ png_image_read_direct(png_voidp argument)

 int PNGAPI
 png_image_finish_read(png_imagep image, png_const_colorp background,
-    void *buffer, png_int_32 row_stride, void *colormap)
+   void *buffer, png_int_32 row_stride, void *colormap)
 {
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      /* Check for row_stride overflow.  This check is not performed on the
-       * original PNG format because it may not occur in the output PNG format
-       * and libpng deals with the issues of reading the original.
-       */
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
+      png_uint_32 check;

-      /* The following checks just the 'row_stride' calculation to ensure it
-       * fits in a signed 32-bit value.  Because channels/components can be
-       * either 1 or 2 bytes in size the length of a row can still overflow 32
-       * bits; this is just to verify that the 'row_stride' argument can be
-       * represented.
-       */
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      if (row_stride == 0)
+         row_stride = PNG_IMAGE_ROW_STRIDE(*image);
+
+      if (row_stride < 0)
+         check = -row_stride;
+
+      else
+         check = row_stride;
+
+      if (image->opaque != NULL && buffer != NULL &&
+         check >= PNG_IMAGE_ROW_STRIDE(*image))
      {
-         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
-
-         if (row_stride == 0)
-            row_stride = (png_int_32)/*SAFE*/png_row_stride;
-
-         if (row_stride < 0)
-            check = -row_stride;
-
-         else
-            check = row_stride;
-
-         /* This verifies 'check', the absolute value of the actual stride
-          * passed in and detects overflow in the application calculation (i.e.
-          * if the app did actually pass in a non-zero 'row_stride'.
-          */
-         if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
+         if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
+            (image->colormap_entries > 0 && colormap != NULL))
         {
-            /* Now check for overflow of the image buffer calculation; this
-             * limits the whole image size to 32 bits for API compatibility with
-             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
-             *
-             * The PNG_IMAGE_BUFFER_SIZE macro is:
-             *
-             *    (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
-             *
-             * And the component size is always 1 or 2, so make sure that the
-             * number of *bytes* that the application is saying are available
-             * does actually fit into a 32-bit number.
-             *
-             * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
-             * will be changed to use png_alloc_size_t; bigger images can be
-             * accomodated on 64-bit systems.
+            int result;
+            png_image_read_control display;
+
+            memset(&display, 0, (sizeof display));
+            display.image = image;
+            display.buffer = buffer;
+            display.row_stride = row_stride;
+            display.colormap = colormap;
+            display.background = background;
+            display.local_row = NULL;
+
+            /* Choose the correct 'end' routine; for the color-map case all the
+             * setup has already been done.
             */
-            if (image->height <=
-                0xFFFFFFFFU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
-            {
-               if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
-                  (image->colormap_entries > 0 && colormap != NULL))
-               {
-                  int result;
-                  png_image_read_control display;
-
-                  memset(&display, 0, (sizeof display));
-                  display.image = image;
-                  display.buffer = buffer;
-                  display.row_stride = row_stride;
-                  display.colormap = colormap;
-                  display.background = background;
-                  display.local_row = NULL;
-
-                  /* Choose the correct 'end' routine; for the color-map case
-                   * all the setup has already been done.
-                   */
-                  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
-                     result =
-                         png_safe_execute(image,
-                             png_image_read_colormap, &display) &&
-                             png_safe_execute(image,
-                             png_image_read_colormapped, &display);
-
-                  else
-                     result =
-                        png_safe_execute(image,
-                            png_image_read_direct, &display);
-
-                  png_image_free(image);
-                  return result;
-               }
-
-               else
-                  return png_image_error(image,
-                      "png_image_finish_read[color-map]: no color-map");
-            }
+            if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
+               result =
+                  png_safe_execute(image, png_image_read_colormap, &display) &&
+                  png_safe_execute(image, png_image_read_colormapped, &display);

            else
-               return png_image_error(image,
-                   "png_image_finish_read: image too large");
+               result =
+                  png_safe_execute(image, png_image_read_direct, &display);
+
+            png_image_free(image);
+            return result;
         }

         else
            return png_image_error(image,
-                "png_image_finish_read: invalid argument");
+               "png_image_finish_read[color-map]: no color-map");
      }

      else
         return png_image_error(image,
-             "png_image_finish_read: row_stride too large");
+            "png_image_finish_read: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_finish_read: damaged PNG_IMAGE_VERSION");
+         "png_image_finish_read: damaged PNG_IMAGE_VERSION");

   return 0;
 }
--- a/pngrio.c
+++ b/pngrio.c
@@ -1,8 +1,8 @@

 /* pngrio.c - functions for data input
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -85,7 +85,7 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 */
 void PNGAPI
 png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr,
-    png_rw_ptr read_data_fn)
+   png_rw_ptr read_data_fn)
 {
   if (png_ptr == NULL)
      return;
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,8 +1,8 @@

 /* pngrtran.c - transforms the data in a row for PNG readers
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -48,7 +48,7 @@ png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)

      case PNG_CRC_WARN_DISCARD:    /* Not a valid action for critical data */
         png_warning(png_ptr,
-             "Can't discard critical data on CRC error");
+            "Can't discard critical data on CRC error");
      case PNG_CRC_ERROR_QUIT:                                /* Error/quit */

      case PNG_CRC_DEFAULT:
@@ -101,7 +101,7 @@ png_rtran_ok(png_structrp png_ptr, int need_IHDR)
   {
      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
         png_app_error(png_ptr,
-             "invalid after png_start_read_image or png_read_update_info");
+            "invalid after png_start_read_image or png_read_update_info");

      else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
         png_app_error(png_ptr, "invalid before the PNG header has been read");
@@ -159,7 +159,7 @@ png_set_background(png_structrp png_ptr,
   png_set_background_fixed(png_ptr, background_color, background_gamma_code,
      need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
 }
-#  endif /* FLOATING_POINT */
+#  endif  /* FLOATING_POINT */
 #endif /* READ_BACKGROUND */

 /* Scale 16-bit depth files to 8-bit depth.  If both of these are set then the
@@ -209,7 +209,7 @@ png_set_strip_alpha(png_structrp png_ptr)
 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
 static png_fixed_point
 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
-    int is_screen)
+   int is_screen)
 {
   /* Check for flag values.  The main reason for having the old Mac value as a
    * flag is that it is pretty near impossible to work out what the correct
@@ -273,7 +273,7 @@ convert_gamma_value(png_structrp png_ptr, double output_gamma)
 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
 void PNGFAPI
 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
-    png_fixed_point output_gamma)
+   png_fixed_point output_gamma)
 {
   int compose = 0;
   png_fixed_point file_gamma;
@@ -289,12 +289,9 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
    * is expected to be 1 or greater, but this range test allows for some
    * viewing correction values.  The intent is to weed out users of this API
    * who use the inverse of the gamma value accidentally!  Since some of these
-    * values are reasonable this may have to be changed:
-    *
-    * 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit
-    * gamma of 36, and its reciprocal.)
+    * values are reasonable this may have to be changed.
    */
-   if (output_gamma < 1000 || output_gamma > 10000000)
+   if (output_gamma < 70000 || output_gamma > 300000)
      png_error(png_ptr, "output gamma out of expected range");

   /* The default file gamma is the inverse of the output gamma; the output
@@ -377,7 +374,7 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,

      if ((png_ptr->transformations & PNG_COMPOSE) != 0)
         png_error(png_ptr,
-             "conflicting calls to set alpha mode and background");
+            "conflicting calls to set alpha mode and background");

      png_ptr->transformations |= PNG_COMPOSE;
   }
@@ -388,7 +385,7 @@ void PNGAPI
 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
 {
   png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
-       output_gamma));
+      output_gamma));
 }
 #  endif
 #endif
@@ -802,7 +799,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
 #ifdef PNG_READ_GAMMA_SUPPORTED
 void PNGFAPI
 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
-    png_fixed_point file_gamma)
+   png_fixed_point file_gamma)
 {
   png_debug(1, "in png_set_gamma_fixed");

@@ -844,7 +841,7 @@ void PNGAPI
 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
 {
   png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
-       convert_gamma_value(png_ptr, file_gamma));
+      convert_gamma_value(png_ptr, file_gamma));
 }
 #  endif /* FLOATING_POINT */
 #endif /* READ_GAMMA */
@@ -990,7 +987,7 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
       * that it just worked and get a memory overwrite.
       */
      png_error(png_ptr,
-          "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
+        "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");

      /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
   }
@@ -1017,7 +1014,7 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
      {
         if (red >= 0 && green >= 0)
            png_app_warning(png_ptr,
-                "ignoring out of range rgb_to_gray coefficients");
+               "ignoring out of range rgb_to_gray coefficients");

         /* Use the defaults, from the cHRM chunk if set, else the historical
          * values which are close to the sRGB/HDTV/ITU-Rec 709 values.  See
@@ -1026,7 +1023,7 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
          * something has already provided a default.
          */
         if (png_ptr->rgb_to_gray_red_coeff == 0 &&
-             png_ptr->rgb_to_gray_green_coeff == 0)
+            png_ptr->rgb_to_gray_green_coeff == 0)
         {
            png_ptr->rgb_to_gray_red_coeff   = 6968;
            png_ptr->rgb_to_gray_green_coeff = 23434;
@@ -1043,10 +1040,10 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,

 void PNGAPI
 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
-    double green)
+   double green)
 {
   png_set_rgb_to_gray_fixed(png_ptr, error_action,
-       png_fixed(png_ptr, red, "rgb to gray red coefficient"),
+      png_fixed(png_ptr, red, "rgb to gray red coefficient"),
      png_fixed(png_ptr, green, "rgb to gray green coefficient"));
 }
 #endif /* FLOATING POINT */
@@ -1303,7 +1300,7 @@ png_init_read_transformations(png_structrp png_ptr)
      {
         if (png_ptr->screen_gamma != 0) /* screen set too */
            gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
-                png_ptr->screen_gamma);
+               png_ptr->screen_gamma);

         else
            /* Assume the output matches the input; a long time default behavior
@@ -1584,7 +1581,7 @@ png_init_read_transformations(png_structrp png_ptr)
          */
         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
            png_warning(png_ptr,
-                "libpng does not support gamma+background+rgb_to_gray");
+               "libpng does not support gamma+background+rgb_to_gray");

         if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
         {
@@ -1620,13 +1617,13 @@ png_init_read_transformations(png_structrp png_ptr)
                  case PNG_BACKGROUND_GAMMA_FILE:
                     g = png_reciprocal(png_ptr->colorspace.gamma);
                     gs = png_reciprocal2(png_ptr->colorspace.gamma,
-                         png_ptr->screen_gamma);
+                        png_ptr->screen_gamma);
                     break;

                  case PNG_BACKGROUND_GAMMA_UNIQUE:
                     g = png_reciprocal(png_ptr->background_gamma);
                     gs = png_reciprocal2(png_ptr->background_gamma,
-                         png_ptr->screen_gamma);
+                        png_ptr->screen_gamma);
                     break;
                  default:
                     g = PNG_FP_1;    /* back_1 */
@@ -1654,11 +1651,11 @@ png_init_read_transformations(png_structrp png_ptr)
               if (png_gamma_significant(g) != 0)
               {
                  back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
-                      g);
+                     g);
                  back_1.green = png_gamma_8bit_correct(
-                      png_ptr->background.green, g);
+                     png_ptr->background.green, g);
                  back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
-                      g);
+                     g);
               }

               else
@@ -1729,7 +1726,7 @@ png_init_read_transformations(png_structrp png_ptr)
               case PNG_BACKGROUND_GAMMA_FILE:
                  g = png_reciprocal(png_ptr->colorspace.gamma);
                  gs = png_reciprocal2(png_ptr->colorspace.gamma,
-                      png_ptr->screen_gamma);
+                     png_ptr->screen_gamma);
                  break;

               case PNG_BACKGROUND_GAMMA_UNIQUE:
@@ -1915,7 +1912,7 @@ png_init_read_transformations(png_structrp png_ptr)
            png_ptr->palette[i].blue = (png_byte)component;
         }
   }
-#endif /* READ_SHIFT */
+#endif  /* READ_SHIFT */
 }

 /* Modify the info structure to reflect the transformations.  The
@@ -4195,7 +4192,7 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 */
 static void
 png_do_expand_palette(png_row_infop row_info, png_bytep row,
-    png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
+   png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
 {
   int shift, value;
   png_bytep sp, dp;
@@ -4502,7 +4499,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
            row_info->channels = 2;
            row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
            row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
-                row_width);
+               row_width);
         }
      }
      else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
@@ -4762,7 +4759,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
       (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
       row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-          0 /* at_start == false, because SWAP_ALPHA happens later */);
+         0 /* at_start == false, because SWAP_ALPHA happens later */);
 #endif

 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,8 +1,8 @@

 /* pngrutil.c - utilities to read a PNG file
 *
- * Last changed in libpng 1.6.25 [September 1, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.20 [December 3, 2014]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -90,7 +90,7 @@ png_get_int_32)(png_const_bytep buf)

   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
   if ((uval & 0x80000000) == 0) /* no overflow */
-      return -(png_int_32)uval;
+       return -(png_int_32)uval;
   /* The following has to be safe; this function only gets called on PNG data
    * and if we get here that data is invalid.  0 is the most safe value and
    * if not then an attacker would surely just generate a PNG with 0 instead.
@@ -461,7 +461,6 @@ png_zlib_inflate(png_structrp png_ptr, int flush)
 #endif /* Zlib >= 1.2.4 */

 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
-#if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
 * allow the caller to do multiple calls if required.  If the 'finish' flag is
 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
@@ -600,9 +599,9 @@ png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
 */
 static int
 png_decompress_chunk(png_structrp png_ptr,
-    png_uint_32 chunklength, png_uint_32 prefix_size,
-    png_alloc_size_t *newlength /* must be initialized to the maximum! */,
-    int terminate /*add a '\0' to the end of the uncompressed data*/)
+   png_uint_32 chunklength, png_uint_32 prefix_size,
+   png_alloc_size_t *newlength /* must be initialized to the maximum! */,
+   int terminate /*add a '\0' to the end of the uncompressed data*/)
 {
   /* TODO: implement different limits for different types of chunk.
    *
@@ -639,8 +638,8 @@ png_decompress_chunk(png_structrp png_ptr,
         png_uint_32 lzsize = chunklength - prefix_size;

         ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
-             /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
-             /* output: */ NULL, newlength);
+            /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
+            /* output: */ NULL, newlength);

         if (ret == Z_STREAM_END)
         {
@@ -660,15 +659,15 @@ png_decompress_chunk(png_structrp png_ptr,
                */
               png_alloc_size_t new_size = *newlength;
               png_alloc_size_t buffer_size = prefix_size + new_size +
-                   (terminate != 0);
+                  (terminate != 0);
               png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
-                   buffer_size));
+                  buffer_size));

               if (text != NULL)
               {
                  ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
-                      png_ptr->read_buffer + prefix_size, &lzsize,
-                      text + prefix_size, newlength);
+                     png_ptr->read_buffer + prefix_size, &lzsize,
+                     text + prefix_size, newlength);

                  if (ret == Z_STREAM_END)
                  {
@@ -755,7 +754,6 @@ png_decompress_chunk(png_structrp png_ptr,
      return Z_MEM_ERROR;
   }
 }
-#endif /* READ_zTXt || READ_iTXt */
 #endif /* READ_COMPRESSED_TEXT */

 #ifdef PNG_READ_iCCP_SUPPORTED
@@ -764,8 +762,8 @@ png_decompress_chunk(png_structrp png_ptr,
 */
 static int
 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
-    png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
-    int finish)
+   png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
+   int finish)
 {
   if (png_ptr->zowner == png_ptr->chunk_name)
   {
@@ -804,8 +802,8 @@ png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
          * the available output is produced; this allows reading of truncated
          * streams.
          */
-         ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
-             Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
+         ret = PNG_INFLATE(png_ptr,
+            *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
      }
      while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));

@@ -1294,7 +1292,7 @@ png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
   (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
-       1/*prefer cHRM values*/);
+      1/*prefer cHRM values*/);
   png_colorspace_sync(png_ptr, info_ptr);
 }
 #endif
@@ -1434,8 +1432,8 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
               png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
               png_ptr->zstream.avail_in = read_length;
               (void)png_inflate_read(png_ptr, local_buffer,
-                   (sizeof local_buffer), &length, profile_header, &size,
-                   0/*finish: don't, because the output is too small*/);
+                  (sizeof local_buffer), &length, profile_header, &size,
+                  0/*finish: don't, because the output is too small*/);

               if (size == 0)
               {
@@ -1445,14 +1443,14 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                     png_get_uint_32(profile_header);

                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
-                      keyword, profile_length) != 0)
+                     keyword, profile_length) != 0)
                  {
                     /* The length is apparently ok, so we can check the 132
                      * byte header.
                      */
                     if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
-                         keyword, profile_length, profile_header,
-                         png_ptr->color_type) != 0)
+                        keyword, profile_length, profile_header,
+                        png_ptr->color_type) != 0)
                     {
                        /* Now read the tag table; a variable size buffer is
                         * needed at this point, allocate one for the whole
@@ -1460,20 +1458,20 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                         * that none of these stuff will overflow.
                         */
                        const png_uint_32 tag_count = png_get_uint_32(
-                            profile_header+128);
+                           profile_header+128);
                        png_bytep profile = png_read_buffer(png_ptr,
-                            profile_length, 2/*silent*/);
+                           profile_length, 2/*silent*/);

                        if (profile != NULL)
                        {
                           memcpy(profile, profile_header,
-                               (sizeof profile_header));
+                              (sizeof profile_header));

                           size = 12 * tag_count;

                           (void)png_inflate_read(png_ptr, local_buffer,
-                               (sizeof local_buffer), &length,
-                               profile + (sizeof profile_header), &size, 0);
+                              (sizeof local_buffer), &length,
+                              profile + (sizeof profile_header), &size, 0);

                           /* Still expect a buffer error because we expect
                            * there to be some tag data!
@@ -1481,22 +1479,22 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                           if (size == 0)
                           {
                              if (png_icc_check_tag_table(png_ptr,
-                                  &png_ptr->colorspace, keyword, profile_length,
-                                  profile) != 0)
+                                 &png_ptr->colorspace, keyword, profile_length,
+                                 profile) != 0)
                              {
                                 /* The profile has been validated for basic
                                  * security issues, so read the whole thing in.
                                  */
                                 size = profile_length - (sizeof profile_header)
-                                     - 12 * tag_count;
+                                    - 12 * tag_count;

                                 (void)png_inflate_read(png_ptr, local_buffer,
-                                     (sizeof local_buffer), &length,
-                                     profile + (sizeof profile_header) +
-                                     12 * tag_count, &size, 1/*finish*/);
+                                    (sizeof local_buffer), &length,
+                                    profile + (sizeof profile_header) +
+                                    12 * tag_count, &size, 1/*finish*/);

                                 if (length > 0 && !(png_ptr->flags &
-                                     PNG_FLAG_BENIGN_ERRORS_WARN))
+                                       PNG_FLAG_BENIGN_ERRORS_WARN))
                                    errmsg = "extra compressed data";

                                 /* But otherwise allow extra data: */
@@ -1508,34 +1506,34 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                                        * keep going.
                                        */
                                       png_chunk_warning(png_ptr,
-                                           "extra compressed data");
+                                          "extra compressed data");
                                    }

                                    png_crc_finish(png_ptr, length);
                                    finished = 1;

-# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
+#                                   ifdef PNG_sRGB_SUPPORTED
                                    /* Check for a match against sRGB */
                                    png_icc_set_sRGB(png_ptr,
-                                        &png_ptr->colorspace, profile,
-                                        png_ptr->zstream.adler);
-# endif
+                                       &png_ptr->colorspace, profile,
+                                       png_ptr->zstream.adler);
+#                                   endif

                                    /* Steal the profile for info_ptr. */
                                    if (info_ptr != NULL)
                                    {
                                       png_free_data(png_ptr, info_ptr,
-                                           PNG_FREE_ICCP, 0);
+                                          PNG_FREE_ICCP, 0);

                                       info_ptr->iccp_name = png_voidcast(char*,
-                                           png_malloc_base(png_ptr,
-                                           keyword_length+1));
+                                          png_malloc_base(png_ptr,
+                                          keyword_length+1));
                                       if (info_ptr->iccp_name != NULL)
                                       {
                                          memcpy(info_ptr->iccp_name, keyword,
-                                              keyword_length+1);
+                                             keyword_length+1);
                                          info_ptr->iccp_proflen =
-                                              profile_length;
+                                             profile_length;
                                          info_ptr->iccp_profile = profile;
                                          png_ptr->read_buffer = NULL; /*steal*/
                                          info_ptr->free_me |= PNG_FREE_ICCP;
@@ -2272,7 +2270,7 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }

   png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
-       (png_charp)units, params);
+      (png_charp)units, params);

   png_free(png_ptr, params);
 }
@@ -2315,7 +2313,7 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }

   png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
-       length + 1);
+      length + 1);

   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);

@@ -2367,7 +2365,7 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      else
         /* This is the (only) success case. */
         png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
-             (png_charp)buffer+1, (png_charp)buffer+heighti);
+            (png_charp)buffer+1, (png_charp)buffer+heighti);
   }
 }
 #endif
@@ -2467,8 +2465,8 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   if (buffer == NULL)
   {
-      png_chunk_benign_error(png_ptr, "out of memory");
-      return;
+     png_chunk_benign_error(png_ptr, "out of memory");
+     return;
   }

   png_crc_read(png_ptr, buffer, length);
@@ -2575,7 +2573,7 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
       * and text chunks.
       */
      if (png_decompress_chunk(png_ptr, length, keyword_length+2,
-          &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+         &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
      {
         png_text text;

@@ -2715,7 +2713,7 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
          * iCCP and text chunks.
          */
         if (png_decompress_chunk(png_ptr, length, prefix_length,
-             &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+            &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
            buffer = png_ptr->read_buffer;

         else
@@ -2795,7 +2793,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
      {
         /* Do a 'warn' here - it is handled below. */
         png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
-             png_malloc_warn(png_ptr, length));
+            png_malloc_warn(png_ptr, length));
      }
   }

@@ -2820,7 +2818,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
 /* Handle an unknown, or known but disabled, chunk */
 void /* PRIVATE */
 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
-    png_uint_32 length, int keep)
+   png_uint_32 length, int keep)
 {
   int handled = 0; /* the chunk was handled */

@@ -2858,7 +2856,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
      {
         /* Callback to user unknown chunk handler */
         int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
-             &png_ptr->unknown_chunk);
+            &png_ptr->unknown_chunk);

         /* ret is:
          * negative: An error occurred; png_chunk_error will be called.
@@ -2892,9 +2890,9 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
               {
                  png_chunk_warning(png_ptr, "Saving unknown chunk:");
                  png_app_warning(png_ptr,
-                      "forcing save of an unhandled chunk;"
-                      " please call png_set_keep_unknown_chunks");
-                      /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
+                     "forcing save of an unhandled chunk;"
+                     " please call png_set_keep_unknown_chunks");
+                     /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
               }
 #              endif
               keep = PNG_HANDLE_CHUNK_IF_SAFE;
@@ -2987,7 +2985,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
             * out; store the chunk.
             */
            png_set_unknown_chunks(png_ptr, info_ptr,
-                &png_ptr->unknown_chunk, 1);
+               &png_ptr->unknown_chunk, 1);
            handled = 1;
 #  ifdef PNG_USER_LIMITS_SUPPORTED
            break;
@@ -3420,8 +3418,8 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
                  /* Everything is aligned for png_uint_16 copies, but try for
                   * png_uint_32 first.
                   */
-                  if (png_isaligned(dp, png_uint_32) &&
-                      png_isaligned(sp, png_uint_32) &&
+                  if (png_isaligned(dp, png_uint_32) != 0 &&
+                      png_isaligned(sp, png_uint_32) != 0 &&
                      bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
                      bytes_to_jump % (sizeof (png_uint_32)) == 0)
                  {
@@ -3541,7 +3539,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 void /* PRIVATE */
 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
-    png_uint_32 transformations /* Because these may affect the byte layout */)
+   png_uint_32 transformations /* Because these may affect the byte layout */)
 {
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Offset to next interlace block */
@@ -3785,7 +3783,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,

 static void
 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row)
+   png_const_bytep prev_row)
 {
   png_size_t i;
   png_size_t istop = row_info->rowbytes;
@@ -3803,7 +3801,7 @@ png_read_filter_row_sub(png_row_infop row_info, png_bytep row,

 static void
 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row)
+   png_const_bytep prev_row)
 {
   png_size_t i;
   png_size_t istop = row_info->rowbytes;
@@ -3819,7 +3817,7 @@ png_read_filter_row_up(png_row_infop row_info, png_bytep row,

 static void
 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row)
+   png_const_bytep prev_row)
 {
   png_size_t i;
   png_bytep rp = row;
@@ -3846,7 +3844,7 @@ png_read_filter_row_avg(png_row_infop row_info, png_bytep row,

 static void
 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row)
+   png_const_bytep prev_row)
 {
   png_bytep rp_end = row + row_info->rowbytes;
   int a, c;
@@ -3894,7 +3892,7 @@ png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,

 static void
 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row)
+   png_const_bytep prev_row)
 {
   int bpp = (row_info->pixel_depth + 7) >> 3;
   png_bytep rp_end = row + bpp;
@@ -3979,7 +3977,7 @@ png_init_filter_functions(png_structrp pp)

 void /* PRIVATE */
 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row, int filter)
+   png_const_bytep prev_row, int filter)
 {
   /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
    * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
@@ -3997,7 +3995,7 @@ png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
-    png_alloc_size_t avail_out)
+   png_alloc_size_t avail_out)
 {
   /* Loop reading IDATs and decompressing the result into output[avail_out] */
   png_ptr->zstream.next_out = output;
@@ -4449,42 +4447,42 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)

   if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
   {
-      png_free(png_ptr, png_ptr->big_row_buf);
-      png_free(png_ptr, png_ptr->big_prev_row);
+     png_free(png_ptr, png_ptr->big_row_buf);
+     png_free(png_ptr, png_ptr->big_prev_row);

-      if (png_ptr->interlaced != 0)
-         png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
-             row_bytes + 48);
+     if (png_ptr->interlaced != 0)
+        png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
+            row_bytes + 48);

-      else
-         png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+     else
+        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);

-      png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+     png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);

 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
-      /* Use 16-byte aligned memory for row_buf with at least 16 bytes
-       * of padding before and after row_buf; treat prev_row similarly.
-       * NOTE: the alignment is to the start of the pixels, one beyond the start
-       * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
-       * was incorrect; the filter byte was aligned, which had the exact
-       * opposite effect of that intended.
-       */
-      {
-         png_bytep temp = png_ptr->big_row_buf + 32;
-         int extra = (int)((temp - (png_bytep)0) & 0x0f);
-         png_ptr->row_buf = temp - extra - 1/*filter byte*/;
+     /* Use 16-byte aligned memory for row_buf with at least 16 bytes
+      * of padding before and after row_buf; treat prev_row similarly.
+      * NOTE: the alignment is to the start of the pixels, one beyond the start
+      * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
+      * was incorrect; the filter byte was aligned, which had the exact
+      * opposite effect of that intended.
+      */
+     {
+        png_bytep temp = png_ptr->big_row_buf + 32;
+        int extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->row_buf = temp - extra - 1/*filter byte*/;

-         temp = png_ptr->big_prev_row + 32;
-         extra = (int)((temp - (png_bytep)0) & 0x0f);
-         png_ptr->prev_row = temp - extra - 1/*filter byte*/;
-      }
+        temp = png_ptr->big_prev_row + 32;
+        extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->prev_row = temp - extra - 1/*filter byte*/;
+     }

 #else
-      /* Use 31 bytes of padding before and 17 bytes after row_buf. */
-      png_ptr->row_buf = png_ptr->big_row_buf + 31;
-      png_ptr->prev_row = png_ptr->big_prev_row + 31;
+     /* Use 31 bytes of padding before and 17 bytes after row_buf. */
+     png_ptr->row_buf = png_ptr->big_row_buf + 31;
+     png_ptr->prev_row = png_ptr->big_prev_row + 31;
 #endif
-      png_ptr->old_big_row_buf_size = row_bytes + 48;
+     png_ptr->old_big_row_buf_size = row_bytes + 48;
   }

 #ifdef PNG_MAX_MALLOC_64K
--- a/pngset.c
+++ b/pngset.c
@@ -1,8 +1,8 @@

 /* pngset.c - storage of image information into info struct
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.21 [January 15, 2016]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -104,14 +104,14 @@ png_set_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
    double green_x, double green_y, double blue_x, double blue_y)
 {
   png_set_cHRM_fixed(png_ptr, info_ptr,
-       png_fixed(png_ptr, white_x, "cHRM White X"),
-       png_fixed(png_ptr, white_y, "cHRM White Y"),
-       png_fixed(png_ptr, red_x, "cHRM Red X"),
-       png_fixed(png_ptr, red_y, "cHRM Red Y"),
-       png_fixed(png_ptr, green_x, "cHRM Green X"),
-       png_fixed(png_ptr, green_y, "cHRM Green Y"),
-       png_fixed(png_ptr, blue_x, "cHRM Blue X"),
-       png_fixed(png_ptr, blue_y, "cHRM Blue Y"));
+      png_fixed(png_ptr, white_x, "cHRM White X"),
+      png_fixed(png_ptr, white_y, "cHRM White Y"),
+      png_fixed(png_ptr, red_x, "cHRM Red X"),
+      png_fixed(png_ptr, red_y, "cHRM Red Y"),
+      png_fixed(png_ptr, green_x, "cHRM Green X"),
+      png_fixed(png_ptr, green_y, "cHRM Green Y"),
+      png_fixed(png_ptr, blue_x, "cHRM Blue X"),
+      png_fixed(png_ptr, blue_y, "cHRM Blue Y"));
 }

 void PNGAPI
@@ -120,15 +120,15 @@ png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
    double blue_X, double blue_Y, double blue_Z)
 {
   png_set_cHRM_XYZ_fixed(png_ptr, info_ptr,
-       png_fixed(png_ptr, red_X, "cHRM Red X"),
-       png_fixed(png_ptr, red_Y, "cHRM Red Y"),
-       png_fixed(png_ptr, red_Z, "cHRM Red Z"),
-       png_fixed(png_ptr, green_X, "cHRM Green X"),
-       png_fixed(png_ptr, green_Y, "cHRM Green Y"),
-       png_fixed(png_ptr, green_Z, "cHRM Green Z"),
-       png_fixed(png_ptr, blue_X, "cHRM Blue X"),
-       png_fixed(png_ptr, blue_Y, "cHRM Blue Y"),
-       png_fixed(png_ptr, blue_Z, "cHRM Blue Z"));
+      png_fixed(png_ptr, red_X, "cHRM Red X"),
+      png_fixed(png_ptr, red_Y, "cHRM Red Y"),
+      png_fixed(png_ptr, red_Z, "cHRM Red Z"),
+      png_fixed(png_ptr, green_X, "cHRM Green X"),
+      png_fixed(png_ptr, green_Y, "cHRM Green Y"),
+      png_fixed(png_ptr, green_Z, "cHRM Green Z"),
+      png_fixed(png_ptr, blue_X, "cHRM Blue X"),
+      png_fixed(png_ptr, blue_Y, "cHRM Blue Y"),
+      png_fixed(png_ptr, blue_Z, "cHRM Blue Z"));
 }
 #  endif /* FLOATING_POINT */

@@ -316,10 +316,10 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,

   length = strlen(units) + 1;
   png_debug1(3, "allocating units for info (%lu bytes)",
-       (unsigned long)length);
+     (unsigned long)length);

   info_ptr->pcal_units = png_voidcast(png_charp,
-       png_malloc_warn(png_ptr, length));
+      png_malloc_warn(png_ptr, length));

   if (info_ptr->pcal_units == NULL)
   {
@@ -398,7 +398,7 @@ png_set_sCAL_s(png_const_structrp png_ptr, png_inforp info_ptr,
   png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthw);

   info_ptr->scal_s_width = png_voidcast(png_charp,
-       png_malloc_warn(png_ptr, lengthw));
+      png_malloc_warn(png_ptr, lengthw));

   if (info_ptr->scal_s_width == NULL)
   {
@@ -414,7 +414,7 @@ png_set_sCAL_s(png_const_structrp png_ptr, png_inforp info_ptr,
   png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthh);

   info_ptr->scal_s_height = png_voidcast(png_charp,
-       png_malloc_warn(png_ptr, lengthh));
+      png_malloc_warn(png_ptr, lengthh));

   if (info_ptr->scal_s_height == NULL)
   {
@@ -453,9 +453,9 @@ png_set_sCAL(png_const_structrp png_ptr, png_inforp info_ptr, int unit,
      char sheight[PNG_sCAL_MAX_DIGITS+1];

      png_ascii_from_fp(png_ptr, swidth, (sizeof swidth), width,
-          PNG_sCAL_PRECISION);
+         PNG_sCAL_PRECISION);
      png_ascii_from_fp(png_ptr, sheight, (sizeof sheight), height,
-          PNG_sCAL_PRECISION);
+         PNG_sCAL_PRECISION);

      png_set_sCAL_s(png_ptr, info_ptr, unit, swidth, sheight);
   }
@@ -648,7 +648,7 @@ png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
    */
   {
      int result = png_colorspace_set_ICC(png_ptr, &info_ptr->colorspace, name,
-          proflen, profile, info_ptr->color_type);
+         proflen, profile, info_ptr->color_type);

      png_colorspace_sync_info(png_ptr, info_ptr);

@@ -673,7 +673,7 @@ png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,

   memcpy(new_iccp_name, name, length);
   new_iccp_profile = png_voidcast(png_bytep,
-       png_malloc_warn(png_ptr, proflen));
+      png_malloc_warn(png_ptr, proflen));

   if (new_iccp_profile == NULL)
   {
@@ -748,14 +748,14 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
          * the overflow checks.
          */
         new_text = png_voidcast(png_textp,png_realloc_array(png_ptr,
-             info_ptr->text, old_num_text, max_text-old_num_text,
-             sizeof *new_text));
+            info_ptr->text, old_num_text, max_text-old_num_text,
+            sizeof *new_text));
      }

      if (new_text == NULL)
      {
         png_chunk_report(png_ptr, "too many text chunks",
-             PNG_CHUNK_WRITE_ERROR);
+            PNG_CHUNK_WRITE_ERROR);

         return 1;
      }
@@ -783,7 +783,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
          text_ptr[i].compression >= PNG_TEXT_COMPRESSION_LAST)
      {
         png_chunk_report(png_ptr, "text compression mode is out of range",
-             PNG_CHUNK_WRITE_ERROR);
+            PNG_CHUNK_WRITE_ERROR);
         continue;
      }

@@ -815,7 +815,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
 #  else /* iTXt */
      {
         png_chunk_report(png_ptr, "iTXt chunk not supported",
-             PNG_CHUNK_WRITE_ERROR);
+            PNG_CHUNK_WRITE_ERROR);
         continue;
      }
 #  endif
@@ -844,7 +844,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
      if (textp->key == NULL)
      {
         png_chunk_report(png_ptr, "text chunk: out of memory",
-             PNG_CHUNK_WRITE_ERROR);
+               PNG_CHUNK_WRITE_ERROR);

         return 1;
      }
@@ -952,14 +952,12 @@ png_set_tRNS(png_structrp png_ptr, png_inforp info_ptr,

       png_free_data(png_ptr, info_ptr, PNG_FREE_TRNS, 0);

+       /* Changed from num_trans to PNG_MAX_PALETTE_LENGTH in version 1.2.1 */
+       png_ptr->trans_alpha = info_ptr->trans_alpha = png_voidcast(png_bytep,
+         png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH));
+
       if (num_trans > 0 && num_trans <= PNG_MAX_PALETTE_LENGTH)
-       {
-         /* Changed from num_trans to PNG_MAX_PALETTE_LENGTH in version 1.2.1 */
-          info_ptr->trans_alpha = png_voidcast(png_bytep,
-              png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH));
          memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
-       }
-       png_ptr->trans_alpha = info_ptr->trans_alpha;
   }

   if (trans_color != NULL)
@@ -976,7 +974,7 @@ png_set_tRNS(png_structrp png_ptr, png_inforp info_ptr,
             trans_color->green > sample_max ||
             trans_color->blue > sample_max)))
            png_warning(png_ptr,
-                "tRNS chunk has out-of-range samples for bit_depth");
+               "tRNS chunk has out-of-range samples for bit_depth");
      }
 #endif

@@ -1018,8 +1016,8 @@ png_set_sPLT(png_const_structrp png_ptr,
    * overflows.  Notice that the parameters are (int) and (size_t)
    */
   np = png_voidcast(png_sPLT_tp,png_realloc_array(png_ptr,
-       info_ptr->splt_palettes, info_ptr->splt_palettes_num, nentries,
-       sizeof *np));
+      info_ptr->splt_palettes, info_ptr->splt_palettes_num, nentries,
+      sizeof *np));

   if (np == NULL)
   {
@@ -1080,7 +1078,7 @@ png_set_sPLT(png_const_structrp png_ptr,
       * checked it when doing the allocation.
       */
      memcpy(np->entries, entries->entries,
-          entries->nentries * sizeof (png_sPLT_entry));
+         entries->nentries * sizeof (png_sPLT_entry));

      /* Note that 'continue' skips the advance of the out pointer and out
       * count, so an invalid entry is not added.
@@ -1110,10 +1108,10 @@ check_location(png_const_structrp png_ptr, int location)
   {
      /* Write struct, so unknown chunks come from the app */
      png_app_warning(png_ptr,
-          "png_set_unknown_chunks now expects a valid location");
+         "png_set_unknown_chunks now expects a valid location");
      /* Use the old behavior */
      location = (png_byte)(png_ptr->mode &
-          (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT));
+         (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT));
   }

   /* This need not be an internal error - if the app calls
@@ -1136,7 +1134,7 @@ check_location(png_const_structrp png_ptr, int location)

 void PNGAPI
 png_set_unknown_chunks(png_const_structrp png_ptr,
-    png_inforp info_ptr, png_const_unknown_chunkp unknowns, int num_unknowns)
+   png_inforp info_ptr, png_const_unknown_chunkp unknowns, int num_unknowns)
 {
   png_unknown_chunkp np;

@@ -1175,13 +1173,13 @@ png_set_unknown_chunks(png_const_structrp png_ptr,
    * appropriate to read or write.
    */
   np = png_voidcast(png_unknown_chunkp, png_realloc_array(png_ptr,
-       info_ptr->unknown_chunks, info_ptr->unknown_chunks_num, num_unknowns,
-       sizeof *np));
+         info_ptr->unknown_chunks, info_ptr->unknown_chunks_num, num_unknowns,
+         sizeof *np));

   if (np == NULL)
   {
      png_chunk_report(png_ptr, "too many unknown chunks",
-          PNG_CHUNK_WRITE_ERROR);
+         PNG_CHUNK_WRITE_ERROR);

      return;
   }
@@ -1210,12 +1208,12 @@ png_set_unknown_chunks(png_const_structrp png_ptr,
      else
      {
         np->data = png_voidcast(png_bytep,
-             png_malloc_base(png_ptr, unknowns->size));
+            png_malloc_base(png_ptr, unknowns->size));

         if (np->data == NULL)
         {
            png_chunk_report(png_ptr, "unknown chunk: out of memory",
-                PNG_CHUNK_WRITE_ERROR);
+               PNG_CHUNK_WRITE_ERROR);
            /* But just skip storing the unknown chunk */
            continue;
         }
@@ -1422,7 +1420,7 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
      for (i=0; i<num_chunks; ++i)
      {
         old_num_chunks = add_one_chunk(new_list, old_num_chunks,
-             chunk_list+5*i, keep);
+            chunk_list+5*i, keep);
      }

      /* Now remove any spurious 'default' entries. */
@@ -1502,60 +1500,60 @@ png_set_rows(png_const_structrp png_ptr, png_inforp info_ptr,
 void PNGAPI
 png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
 {
-   if (png_ptr == NULL)
-      return;
+    if (png_ptr == NULL)
+       return;

-   if (size == 0 || size > PNG_UINT_31_MAX)
-      png_error(png_ptr, "invalid compression buffer size");
+    if (size == 0 || size > PNG_UINT_31_MAX)
+       png_error(png_ptr, "invalid compression buffer size");

 #  ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
-   {
-      png_ptr->IDAT_read_size = (png_uint_32)size; /* checked above */
-      return;
-   }
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+      {
+         png_ptr->IDAT_read_size = (png_uint_32)size; /* checked above */
+         return;
+      }
 #  endif

 #  ifdef PNG_WRITE_SUPPORTED
-   if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
-   {
-      if (png_ptr->zowner != 0)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
      {
-         png_warning(png_ptr,
-             "Compression buffer size cannot be changed because it is in use");
+         if (png_ptr->zowner != 0)
+         {
+            png_warning(png_ptr,
+              "Compression buffer size cannot be changed because it is in use");

-         return;
-      }
+            return;
+         }

 #ifndef __COVERITY__
-      /* Some compilers complain that this is always false.  However, it
-       * can be true when integer overflow happens.
-       */
-      if (size > ZLIB_IO_MAX)
-      {
-         png_warning(png_ptr,
-             "Compression buffer size limited to system maximum");
-         size = ZLIB_IO_MAX; /* must fit */
-      }
+         /* Some compilers complain that this is always false.  However, it
+          * can be true when integer overflow happens.
+          */
+         if (size > ZLIB_IO_MAX)
+         {
+            png_warning(png_ptr,
+               "Compression buffer size limited to system maximum");
+            size = ZLIB_IO_MAX; /* must fit */
+         }
 #endif

-      if (size < 6)
-      {
-         /* Deflate will potentially go into an infinite loop on a SYNC_FLUSH
-          * if this is permitted.
-          */
-         png_warning(png_ptr,
-             "Compression buffer size cannot be reduced below 6");
+         if (size < 6)
+         {
+            /* Deflate will potentially go into an infinite loop on a SYNC_FLUSH
+             * if this is permitted.
+             */
+            png_warning(png_ptr,
+               "Compression buffer size cannot be reduced below 6");

-         return;
-      }
+            return;
+         }

-      if (png_ptr->zbuffer_size != size)
-      {
-         png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
-         png_ptr->zbuffer_size = (uInt)size;
+         if (png_ptr->zbuffer_size != size)
+         {
+            png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
+            png_ptr->zbuffer_size = (uInt)size;
+         }
      }
-   }
 #  endif
 }

@@ -1662,9 +1660,7 @@ png_set_check_for_invalid_index(png_structrp png_ptr, int allowed)
 png_uint_32 /* PRIVATE */
 png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
 {
-#ifdef PNG_WARNINGS_SUPPORTED
   png_const_charp orig_key = key;
-#endif
   png_uint_32 key_len = 0;
   int bad_character = 0;
   int space = 1;
@@ -1727,9 +1723,7 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)

      png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
   }
-#else /* !WARNINGS */
-   PNG_UNUSED(png_ptr)
-#endif /* !WARNINGS */
+#endif /* WARNINGS */

   return key_len;
 }
--- a/pngstruct.h
+++ b/pngstruct.h
@@ -1,8 +1,8 @@

 /* pngstruct.h - header file for PNG reference library
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -249,7 +249,7 @@ struct png_struct_def
   png_byte filter;           /* file filter type (always 0) */
   png_byte interlaced;       /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
   png_byte pass;             /* current interlace pass (0 - 6) */
-   png_byte do_filter;        /* row filter flags (see PNG_FILTER_ in png.h ) */
+   png_byte do_filter;        /* row filter flags (see PNG_FILTER_ below ) */
   png_byte color_type;       /* color type of file */
   png_byte bit_depth;        /* bit depth of file */
   png_byte usr_bit_depth;    /* bit depth of users row: write only */
--- a/pngtest.c
+++ b/pngtest.c
@@ -1,8 +1,8 @@

 /* pngtest.c - a simple test program to test libpng
 *
- * Last changed in libpng 1.6.25 [September 1, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.25 [December 3, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -43,15 +43,6 @@

 #include "png.h"

-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 /* Known chunks that exist in pngtest.png must be supported or pngtest will fail
 * simply as a result of re-ordering them.  This may be fixed in 1.7
 *
@@ -139,13 +130,13 @@ static char tIME_string[PNG_tIME_STRING_LENGTH] = "tIME chunk is not present";
 static int
 tIME_to_str(png_structp png_ptr, png_charp ts, png_const_timep t)
 {
-   png_const_charp str = png_convert_to_rfc1123(png_ptr, t);
+    png_const_charp str = png_convert_to_rfc1123(png_ptr, t);

-   if (str == NULL)
-       return 0;
+    if (str == NULL)
+        return 0;

-   strcpy(ts, str);
-   return 1;
+    strcpy(ts, str);
+    return 1;
 }
 #endif /* older libpng */
 #endif
@@ -249,95 +240,95 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
    *  png_byte pixel_depth   bits per pixel (depth*channels)
    */

-   /* Counts the number of zero samples (or zero pixels if color_type is 3 */
+    /* Counts the number of zero samples (or zero pixels if color_type is 3 */

-   if (row_info->color_type == 0 || row_info->color_type == 3)
-   {
-      int pos = 0;
-      png_uint_32 n, nstop;
+    if (row_info->color_type == 0 || row_info->color_type == 3)
+    {
+       int pos = 0;
+       png_uint_32 n, nstop;

-      for (n = 0, nstop=row_info->width; n<nstop; n++)
-      {
-         if (row_info->bit_depth == 1)
-         {
-            if (((*dp << pos++ ) & 0x80) == 0)
-               zero_samples++;
+       for (n = 0, nstop=row_info->width; n<nstop; n++)
+       {
+          if (row_info->bit_depth == 1)
+          {
+             if (((*dp << pos++ ) & 0x80) == 0)
+                zero_samples++;

-            if (pos == 8)
-            {
-               pos = 0;
-               dp++;
-            }
-         }
+             if (pos == 8)
+             {
+                pos = 0;
+                dp++;
+             }
+          }

-         if (row_info->bit_depth == 2)
-         {
-            if (((*dp << (pos+=2)) & 0xc0) == 0)
-               zero_samples++;
+          if (row_info->bit_depth == 2)
+          {
+             if (((*dp << (pos+=2)) & 0xc0) == 0)
+                zero_samples++;

-            if (pos == 8)
-            {
-               pos = 0;
-               dp++;
-            }
-         }
+             if (pos == 8)
+             {
+                pos = 0;
+                dp++;
+             }
+          }

-         if (row_info->bit_depth == 4)
-         {
-            if (((*dp << (pos+=4)) & 0xf0) == 0)
-               zero_samples++;
+          if (row_info->bit_depth == 4)
+          {
+             if (((*dp << (pos+=4)) & 0xf0) == 0)
+                zero_samples++;

-            if (pos == 8)
-            {
-               pos = 0;
-               dp++;
-            }
-         }
+             if (pos == 8)
+             {
+                pos = 0;
+                dp++;
+             }
+          }

-         if (row_info->bit_depth == 8)
-            if (*dp++ == 0)
-               zero_samples++;
+          if (row_info->bit_depth == 8)
+             if (*dp++ == 0)
+                zero_samples++;

-         if (row_info->bit_depth == 16)
-         {
-            if ((*dp | *(dp+1)) == 0)
-               zero_samples++;
-            dp+=2;
-         }
-      }
-   }
-   else /* Other color types */
-   {
-      png_uint_32 n, nstop;
-      int channel;
-      int color_channels = row_info->channels;
-      if (row_info->color_type > 3)
-         color_channels--;
+          if (row_info->bit_depth == 16)
+          {
+             if ((*dp | *(dp+1)) == 0)
+                zero_samples++;
+             dp+=2;
+          }
+       }
+    }
+    else /* Other color types */
+    {
+       png_uint_32 n, nstop;
+       int channel;
+       int color_channels = row_info->channels;
+       if (row_info->color_type > 3)
+          color_channels--;

-      for (n = 0, nstop=row_info->width; n<nstop; n++)
-      {
-         for (channel = 0; channel < color_channels; channel++)
-         {
-            if (row_info->bit_depth == 8)
-               if (*dp++ == 0)
-                  zero_samples++;
+       for (n = 0, nstop=row_info->width; n<nstop; n++)
+       {
+          for (channel = 0; channel < color_channels; channel++)
+          {
+             if (row_info->bit_depth == 8)
+                if (*dp++ == 0)
+                   zero_samples++;

-            if (row_info->bit_depth == 16)
-            {
-               if ((*dp | *(dp+1)) == 0)
-                  zero_samples++;
+             if (row_info->bit_depth == 16)
+             {
+                if ((*dp | *(dp+1)) == 0)
+                   zero_samples++;

-               dp+=2;
-            }
-         }
-         if (row_info->color_type > 3)
-         {
-            dp++;
-            if (row_info->bit_depth == 16)
-               dp++;
-         }
-      }
-   }
+                dp+=2;
+             }
+          }
+          if (row_info->color_type > 3)
+          {
+             dp++;
+             if (row_info->bit_depth == 16)
+                dp++;
+          }
+       }
+    }
 }
 #endif /* WRITE_USER_TRANSFORM */

@@ -354,10 +345,10 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
 #ifdef PNG_IO_STATE_SUPPORTED
 void
 pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
-    png_uint_32 io_op);
+   png_uint_32 io_op);
 void
 pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
-    png_uint_32 io_op)
+   png_uint_32 io_op)
 {
   png_uint_32 io_state = png_get_io_state(png_ptr);
   int err = 0;
@@ -514,10 +505,10 @@ typedef struct memory_information
 typedef memory_information *memory_infop;

 static memory_infop pinformation = NULL;
-static png_alloc_size_t current_allocation = 0;
-static png_alloc_size_t maximum_allocation = 0;
-static png_alloc_size_t total_allocation = 0;
-static png_alloc_size_t num_allocations = 0;
+static int current_allocation = 0;
+static int maximum_allocation = 0;
+static int total_allocation = 0;
+static int num_allocations = 0;

 png_voidp PNGCBAPI png_debug_malloc PNGARG((png_structp png_ptr,
    png_alloc_size_t size));
@@ -541,7 +532,7 @@ PNGCBAPI png_debug_malloc(png_structp png_ptr, png_alloc_size_t size)
      memory_infop pinfo;
      png_set_mem_fn(png_ptr, NULL, NULL, NULL);
      pinfo = (memory_infop)png_malloc(png_ptr,
-          (sizeof *pinfo));
+         (sizeof *pinfo));
      pinfo->size = size;
      current_allocation += size;
      total_allocation += size;
@@ -571,7 +562,7 @@ PNGCBAPI png_debug_malloc(png_structp png_ptr, png_alloc_size_t size)

      if (verbose != 0)
         printf("png_malloc %lu bytes at %p\n", (unsigned long)size,
-             pinfo->pointer);
+            pinfo->pointer);

      return (png_voidp)(pinfo->pointer);
   }
@@ -604,10 +595,9 @@ png_debug_free(png_structp png_ptr, png_voidp ptr)
         if (pinfo->pointer == ptr)
         {
            *ppinfo = pinfo->next;
-            if (current_allocation < pinfo->size)
+            current_allocation -= pinfo->size;
+            if (current_allocation < 0)
               fprintf(STDERR, "Duplicate free of memory\n");
-            else
-               current_allocation -= pinfo->size;
            /* We must free the list element too, but first kill
               the memory that is to be freed. */
            memset(ptr, 0x55, pinfo->size);
@@ -779,9 +769,9 @@ write_vpAg_chunk(png_structp write_ptr)

   if (verbose != 0)
      fprintf(STDERR, " vpAg = %lu x %lu, units = %d\n",
-          (unsigned long)user_chunk_data.vpAg_width,
-          (unsigned long)user_chunk_data.vpAg_height,
-          user_chunk_data.vpAg_units);
+        (unsigned long)user_chunk_data.vpAg_width,
+        (unsigned long)user_chunk_data.vpAg_height,
+        user_chunk_data.vpAg_units);

   png_save_uint_32(vpag_chunk_data, user_chunk_data.vpAg_width);
   png_save_uint_32(vpag_chunk_data + 4, user_chunk_data.vpAg_height);
@@ -822,7 +812,7 @@ write_chunks(png_structp write_ptr, int location)
 #ifdef PNG_TEXT_SUPPORTED
 static void
 pngtest_check_text_support(png_structp png_ptr, png_textp text_ptr,
-    int num_text)
+   int num_text)
 {
   while (num_text > 0)
   {
@@ -904,26 +894,26 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   pngtest_debug("Allocating read and write structures");
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
   read_ptr =
-       png_create_read_struct_2(PNG_LIBPNG_VER_STRING, NULL,
-       NULL, NULL, NULL, png_debug_malloc, png_debug_free);
+      png_create_read_struct_2(PNG_LIBPNG_VER_STRING, NULL,
+      NULL, NULL, NULL, png_debug_malloc, png_debug_free);
 #else
   read_ptr =
-       png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+      png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 #endif
   png_set_error_fn(read_ptr, &error_parameters, pngtest_error,
-       pngtest_warning);
+      pngtest_warning);

 #ifdef PNG_WRITE_SUPPORTED
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
   write_ptr =
-       png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL,
-       NULL, NULL, NULL, png_debug_malloc, png_debug_free);
+      png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL,
+      NULL, NULL, NULL, png_debug_malloc, png_debug_free);
 #else
   write_ptr =
-       png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+      png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 #endif
   png_set_error_fn(write_ptr, &error_parameters, pngtest_error,
-       pngtest_warning);
+      pngtest_warning);
 #endif
   pngtest_debug("Allocating read_info, write_info and end_info structures");
   read_info_ptr = png_create_info_struct(read_ptr);
@@ -936,13 +926,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
   init_callback_info(read_info_ptr);
   png_set_read_user_chunk_fn(read_ptr, &user_chunk_data,
-       read_user_chunk_callback);
-#endif
-
-#ifdef PNG_SET_USER_LIMITS_SUPPORTED
-#  ifdef CHUNK_LIMIT /* from the build, for testing */
-      png_set_chunk_malloc_max(read_ptr, CHUNK_LIMIT);
-#  endif /* CHUNK_LIMIT */
+     read_user_chunk_callback);
 #endif

 #ifdef PNG_SETJMP_SUPPORTED
@@ -1017,9 +1001,9 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #  ifdef PNG_WRITE_SUPPORTED
   png_set_write_fn(write_ptr, (png_voidp)fpout,  pngtest_write_data,
 #    ifdef PNG_WRITE_FLUSH_SUPPORTED
-       pngtest_flush);
+      pngtest_flush);
 #    else
-       NULL);
+      NULL);
 #    endif
 #  endif
 #endif
@@ -1059,11 +1043,11 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
    */
 #ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
   png_set_keep_unknown_chunks(read_ptr, PNG_HANDLE_CHUNK_ALWAYS,
-       NULL, 0);
+      NULL, 0);
 #endif
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
   png_set_keep_unknown_chunks(write_ptr, PNG_HANDLE_CHUNK_ALWAYS,
-       NULL, 0);
+      NULL, 0);
 #endif
 #endif

@@ -1087,7 +1071,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          &color_type, &interlace_type, &compression_type, &filter_type) != 0)
      {
         png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
-             color_type, interlace_type, compression_type, filter_type);
+            color_type, interlace_type, compression_type, filter_type);
         /* num_passes may not be available below if interlace support is not
          * provided by libpng for both read and write.
          */
@@ -1114,13 +1098,13 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #ifdef PNG_cHRM_SUPPORTED
   {
      png_fixed_point white_x, white_y, red_x, red_y, green_x, green_y, blue_x,
-          blue_y;
+         blue_y;

      if (png_get_cHRM_fixed(read_ptr, read_info_ptr, &white_x, &white_y,
-          &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
+         &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
      {
         png_set_cHRM_fixed(write_ptr, write_info_ptr, white_x, white_y, red_x,
-             red_y, green_x, green_y, blue_x, blue_y);
+            red_y, green_x, green_y, blue_x, blue_y);
      }
   }
 #endif
@@ -1137,13 +1121,13 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #ifdef PNG_cHRM_SUPPORTED
   {
      double white_x, white_y, red_x, red_y, green_x, green_y, blue_x,
-          blue_y;
+         blue_y;

      if (png_get_cHRM(read_ptr, read_info_ptr, &white_x, &white_y, &red_x,
-          &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
+         &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
      {
         png_set_cHRM(write_ptr, write_info_ptr, white_x, white_y, red_x,
-             red_y, green_x, green_y, blue_x, blue_y);
+            red_y, green_x, green_y, blue_x, blue_y);
      }
   }
 #endif
@@ -1165,10 +1149,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int compression_type;

      if (png_get_iCCP(read_ptr, read_info_ptr, &name, &compression_type,
-          &profile, &proflen) != 0)
+                      &profile, &proflen) != 0)
      {
         png_set_iCCP(write_ptr, write_info_ptr, name, compression_type,
-             profile, proflen);
+                      profile, proflen);
      }
   }
 #endif
@@ -1225,10 +1209,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int type, nparams;

      if (png_get_pCAL(read_ptr, read_info_ptr, &purpose, &X0, &X1, &type,
-          &nparams, &units, &params) != 0)
+         &nparams, &units, &params) != 0)
      {
         png_set_pCAL(write_ptr, write_info_ptr, purpose, X0, X1, type,
-             nparams, units, params);
+            nparams, units, params);
      }
   }
 #endif
@@ -1258,7 +1242,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      double scal_width, scal_height;

      if (png_get_sCAL(read_ptr, read_info_ptr, &unit, &scal_width,
-          &scal_height) != 0)
+         &scal_height) != 0)
      {
         png_set_sCAL(write_ptr, write_info_ptr, unit, scal_width, scal_height);
      }
@@ -1270,7 +1254,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_charp scal_width, scal_height;

      if (png_get_sCAL_s(read_ptr, read_info_ptr, &unit, &scal_width,
-           &scal_height) != 0)
+          &scal_height) != 0)
      {
         png_set_sCAL_s(write_ptr, write_info_ptr, unit, scal_width,
             scal_height);
@@ -1311,7 +1295,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            for (i=0; i<num_text; i++)
            {
               printf("   Text compression[%d]=%d\n",
-                   i, text_ptr[i].compression);
+                     i, text_ptr[i].compression);
            }
         }

@@ -1348,7 +1332,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_color_16p trans_color;

      if (png_get_tRNS(read_ptr, read_info_ptr, &trans_alpha, &num_trans,
-          &trans_color) != 0)
+         &trans_color) != 0)
      {
         int sample_max = (1 << bit_depth);
         /* libpng doesn't reject a tRNS chunk with out-of-range samples */
@@ -1367,12 +1351,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_unknown_chunkp unknowns;
      int num_unknowns = png_get_unknown_chunks(read_ptr, read_info_ptr,
-          &unknowns);
+         &unknowns);

      if (num_unknowns != 0)
      {
         png_set_unknown_chunks(write_ptr, write_info_ptr, unknowns,
-             num_unknowns);
+           num_unknowns);
 #if PNG_LIBPNG_VER < 10600
         /* Copy the locations from the read_info_ptr.  The automatically
          * generated locations in write_end_info_ptr are wrong prior to 1.6.0
@@ -1382,7 +1366,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            int i;
            for (i = 0; i < num_unknowns; i++)
              png_set_unknown_chunk_location(write_ptr, write_info_ptr, i,
-                  unknowns[i].location);
+                unknowns[i].location);
         }
 #endif
      }
@@ -1407,7 +1391,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #ifdef SINGLE_ROWBUF_ALLOC
   pngtest_debug("Allocating row buffer...");
   row_buf = (png_bytep)png_malloc(read_ptr,
-       png_get_rowbytes(read_ptr, read_info_ptr));
+      png_get_rowbytes(read_ptr, read_info_ptr));

   pngtest_debug1("\t0x%08lx", (unsigned long)row_buf);
 #endif /* SINGLE_ROWBUF_ALLOC */
@@ -1421,10 +1405,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
    */
   if (png_set_interlace_handling(read_ptr) != num_passes)
      png_error(write_ptr,
-          "png_set_interlace_handling(read): wrong pass count ");
+            "png_set_interlace_handling(read): wrong pass count ");
   if (png_set_interlace_handling(write_ptr) != num_passes)
      png_error(write_ptr,
-          "png_set_interlace_handling(write): wrong pass count ");
+            "png_set_interlace_handling(write): wrong pass count ");
 #else /* png_set_interlace_handling not called on either read or write */
 #  define calc_pass_height
 #endif /* not using libpng interlace handling */
@@ -1461,10 +1445,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         pngtest_debug2("Allocating row buffer (pass %d, y = %u)...", pass, y);

         row_buf = (png_bytep)png_malloc(read_ptr,
-             png_get_rowbytes(read_ptr, read_info_ptr));
+            png_get_rowbytes(read_ptr, read_info_ptr));

         pngtest_debug2("\t0x%08lx (%lu bytes)", (unsigned long)row_buf,
-             (unsigned long)png_get_rowbytes(read_ptr, read_info_ptr));
+            (unsigned long)png_get_rowbytes(read_ptr, read_info_ptr));

 #endif /* !SINGLE_ROWBUF_ALLOC */
         png_read_rows(read_ptr, (png_bytepp)&row_buf, NULL, 1);
@@ -1522,7 +1506,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            for (i=0; i<num_text; i++)
            {
               printf("   Text compression[%d]=%d\n",
-                   i, text_ptr[i].compression);
+                     i, text_ptr[i].compression);
            }
         }

@@ -1556,12 +1540,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_unknown_chunkp unknowns;
      int num_unknowns = png_get_unknown_chunks(read_ptr, end_info_ptr,
-          &unknowns);
+         &unknowns);

      if (num_unknowns != 0)
      {
         png_set_unknown_chunks(write_ptr, write_end_info_ptr, unknowns,
-             num_unknowns);
+           num_unknowns);
 #if PNG_LIBPNG_VER < 10600
         /* Copy the locations from the read_info_ptr.  The automatically
          * generated locations in write_end_info_ptr are wrong prior to 1.6.0
@@ -1571,7 +1555,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            int i;
            for (i = 0; i < num_unknowns; i++)
              png_set_unknown_chunk_location(write_ptr, write_end_info_ptr, i,
-                  unknowns[i].location);
+                unknowns[i].location);
         }
 #endif
      }
@@ -1605,7 +1589,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      iwidth = png_get_image_width(write_ptr, write_info_ptr);
      iheight = png_get_image_height(write_ptr, write_info_ptr);
      fprintf(STDERR, "\n Image width = %lu, height = %lu\n",
-          (unsigned long)iwidth, (unsigned long)iheight);
+         (unsigned long)iwidth, (unsigned long)iheight);
   }
 #endif

@@ -1638,7 +1622,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       * above, but this is safe.
       */
      fprintf(STDERR, "\n  %s: %d libpng errors found (%d warnings)",
-          inname, error_count, warning_count);
+         inname, error_count, warning_count);

      if (strict != 0)
         return (1);
@@ -1649,14 +1633,14 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      else if (unsupported_chunks > 0)
      {
         fprintf(STDERR, "\n  %s: unsupported chunks (%d)%s",
-             inname, unsupported_chunks, strict ? ": IGNORED --strict!" : "");
+            inname, unsupported_chunks, strict ? ": IGNORED --strict!" : "");
      }
 #  endif

   else if (warning_count > 0)
   {
      fprintf(STDERR, "\n  %s: %d libpng warnings found",
-          inname, warning_count);
+         inname, warning_count);

      if (strict != 0)
         return (1);
@@ -1692,19 +1676,18 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         if (num_in != num_out)
         {
            fprintf(STDERR, "\nFiles %s and %s are of a different size\n",
-                inname, outname);
+                    inname, outname);

            if (wrote_question == 0 && unsupported_chunks == 0)
            {
               fprintf(STDERR,
-                   "   Was %s written with the same maximum IDAT"
-                   " chunk size (%d bytes),",
-                   inname, PNG_ZBUF_SIZE);
+         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
+                 inname, PNG_ZBUF_SIZE);
               fprintf(STDERR,
-                   "\n   filtering heuristic (libpng default), compression");
+                 "\n   filtering heuristic (libpng default), compression");
               fprintf(STDERR,
-                   " level (zlib default),\n   and zlib version (%s)?\n\n",
-                   ZLIB_VERSION);
+                 " level (zlib default),\n   and zlib version (%s)?\n\n",
+                 ZLIB_VERSION);
               wrote_question = 1;
            }

@@ -1724,18 +1707,17 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         if (memcmp(inbuf, outbuf, num_in))
         {
            fprintf(STDERR, "\nFiles %s and %s are different\n", inname,
-                outname);
+               outname);

            if (wrote_question == 0 && unsupported_chunks == 0)
            {
               fprintf(STDERR,
-                   "   Was %s written with the same maximum"
-                   " IDAT chunk size (%d bytes),",
+         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
                    inname, PNG_ZBUF_SIZE);
               fprintf(STDERR,
-                   "\n   filtering heuristic (libpng default), compression");
+                 "\n   filtering heuristic (libpng default), compression");
               fprintf(STDERR,
-                   " level (zlib default),\n   and zlib version (%s)?\n\n",
+                 " level (zlib default),\n   and zlib version (%s)?\n\n",
                 ZLIB_VERSION);
               wrote_question = 1;
            }
@@ -1786,12 +1768,12 @@ main(int argc, char *argv[])
   fprintf(STDERR, "%s", png_get_copyright(NULL));
   /* Show the version of libpng used in building the library */
   fprintf(STDERR, " library (%lu):%s",
-       (unsigned long)png_access_version_number(),
-       png_get_header_version(NULL));
+      (unsigned long)png_access_version_number(),
+      png_get_header_version(NULL));

   /* Show the version of libpng used in building the application */
   fprintf(STDERR, " pngtest (%lu):%s", (unsigned long)PNG_LIBPNG_VER,
-       PNG_HEADER_VERSION_STRING);
+      PNG_HEADER_VERSION_STRING);

   /* Do some consistency checking on the memory allocation settings, I'm
    * not sure this matters, but it is nice to know, the first of these
@@ -1809,7 +1791,7 @@ main(int argc, char *argv[])
   if (strcmp(png_libpng_ver, PNG_LIBPNG_VER_STRING))
   {
      fprintf(STDERR,
-          "Warning: versions are different between png.h and png.c\n");
+         "Warning: versions are different between png.h and png.c\n");
      fprintf(STDERR, "  png.h version: %s\n", PNG_LIBPNG_VER_STRING);
      fprintf(STDERR, "  png.c version: %s\n\n", png_libpng_ver);
      ++ierror;
@@ -1864,26 +1846,26 @@ main(int argc, char *argv[])
   }

   if (multiple == 0 && argc == 3 + verbose)
-      outname = argv[2 + verbose];
+     outname = argv[2 + verbose];

   if ((multiple == 0 && argc > 3 + verbose) ||
       (multiple != 0 && argc < 2))
   {
-      fprintf(STDERR,
-          "usage: %s [infile.png] [outfile.png]\n\t%s -m {infile.png}\n",
-          argv[0], argv[0]);
-      fprintf(STDERR,
-          "  reads/writes one PNG file (without -m) or multiple files (-m)\n");
-      fprintf(STDERR,
-          "  with -m %s is used as a temporary file\n", outname);
-      exit(1);
+     fprintf(STDERR,
+       "usage: %s [infile.png] [outfile.png]\n\t%s -m {infile.png}\n",
+        argv[0], argv[0]);
+     fprintf(STDERR,
+       "  reads/writes one PNG file (without -m) or multiple files (-m)\n");
+     fprintf(STDERR,
+       "  with -m %s is used as a temporary file\n", outname);
+     exit(1);
   }

   if (multiple != 0)
   {
      int i;
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-      png_alloc_size_t allocation_now = current_allocation;
+      int allocation_now = current_allocation;
 #endif
      for (i=2; i<argc; ++i)
      {
@@ -1897,7 +1879,7 @@ main(int argc, char *argv[])
         {
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
            fprintf(STDERR, "\n PASS (%lu zero samples)\n",
-                (unsigned long)zero_samples);
+               (unsigned long)zero_samples);
 #else
            fprintf(STDERR, " PASS\n");
 #endif
@@ -1916,35 +1898,35 @@ main(int argc, char *argv[])
         }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
-            fprintf(STDERR, "MEMORY ERROR: %lu bytes lost\n",
-                (unsigned long)(current_allocation - allocation_now));
+            fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+               current_allocation - allocation_now);

         if (current_allocation != 0)
         {
            memory_infop pinfo = pinformation;

-            fprintf(STDERR, "MEMORY ERROR: %lu bytes still allocated\n",
-                (unsigned long)current_allocation);
+            fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+               current_allocation);

            while (pinfo != NULL)
            {
               fprintf(STDERR, " %lu bytes at %p\n",
-                   (unsigned long)pinfo->size,
-                   pinfo->pointer);
+                 (unsigned long)pinfo->size,
+                 pinfo->pointer);
               pinfo = pinfo->next;
            }
         }
 #endif
      }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-         fprintf(STDERR, " Current memory allocation: %20lu bytes\n",
-             (unsigned long)current_allocation);
-         fprintf(STDERR, " Maximum memory allocation: %20lu bytes\n",
-             (unsigned long) maximum_allocation);
-         fprintf(STDERR, " Total   memory allocation: %20lu bytes\n",
-             (unsigned long)total_allocation);
-         fprintf(STDERR, "     Number of allocations: %20lu\n",
-             (unsigned long)num_allocations);
+         fprintf(STDERR, " Current memory allocation: %10d bytes\n",
+            current_allocation);
+         fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
+            maximum_allocation);
+         fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
+            total_allocation);
+         fprintf(STDERR, "     Number of allocations: %10d\n",
+            num_allocations);
 #endif
   }

@@ -1955,7 +1937,7 @@ main(int argc, char *argv[])
      {
         int kerror;
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-         png_alloc_size_t allocation_now = current_allocation;
+         int allocation_now = current_allocation;
 #endif
         if (i == 1)
            status_dots_requested = 1;
@@ -1979,7 +1961,7 @@ main(int argc, char *argv[])
            {
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
                fprintf(STDERR, "\n PASS (%lu zero samples)\n",
-                    (unsigned long)zero_samples);
+                   (unsigned long)zero_samples);
 #else
                fprintf(STDERR, " PASS\n");
 #endif
@@ -2005,34 +1987,34 @@ main(int argc, char *argv[])
         }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
-             fprintf(STDERR, "MEMORY ERROR: %lu bytes lost\n",
-                 (unsigned long)(current_allocation - allocation_now));
+             fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+               current_allocation - allocation_now);

         if (current_allocation != 0)
         {
             memory_infop pinfo = pinformation;

-             fprintf(STDERR, "MEMORY ERROR: %lu bytes still allocated\n",
-                 (unsigned long)current_allocation);
+             fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+                current_allocation);

             while (pinfo != NULL)
             {
                fprintf(STDERR, " %lu bytes at %p\n",
-                    (unsigned long)pinfo->size, pinfo->pointer);
+                   (unsigned long)pinfo->size, pinfo->pointer);
                pinfo = pinfo->next;
             }
          }
 #endif
       }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-       fprintf(STDERR, " Current memory allocation: %20lu bytes\n",
-           (unsigned long)current_allocation);
-       fprintf(STDERR, " Maximum memory allocation: %20lu bytes\n",
-           (unsigned long)maximum_allocation);
-       fprintf(STDERR, " Total   memory allocation: %20lu bytes\n",
-           (unsigned long)total_allocation);
-       fprintf(STDERR, "     Number of allocations: %20lu\n",
-           (unsigned long)num_allocations);
+       fprintf(STDERR, " Current memory allocation: %10d bytes\n",
+          current_allocation);
+       fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
+          maximum_allocation);
+       fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
+          total_allocation);
+       fprintf(STDERR, "     Number of allocations: %10d\n",
+            num_allocations);
 #endif
   }

@@ -2041,13 +2023,13 @@ main(int argc, char *argv[])
   t_misc += (t_stop - t_start);
   t_start = t_stop;
   fprintf(STDERR, " CPU time used = %.3f seconds",
-       (t_misc+t_decode+t_encode)/(float)CLOCKS_PER_SEC);
+      (t_misc+t_decode+t_encode)/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, " (decoding %.3f,\n",
-       t_decode/(float)CLOCKS_PER_SEC);
+      t_decode/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, "        encoding %.3f ,",
-       t_encode/(float)CLOCKS_PER_SEC);
+      t_encode/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, " other %.3f seconds)\n\n",
-       t_misc/(float)CLOCKS_PER_SEC);
+      t_misc/(float)CLOCKS_PER_SEC);
 #endif

   if (ierror == 0)
@@ -2059,19 +2041,19 @@ main(int argc, char *argv[])
   dummy_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   fprintf(STDERR, " Default limits:\n");
   fprintf(STDERR, "  width_max  = %lu\n",
-       (unsigned long) png_get_user_width_max(dummy_ptr));
+      (unsigned long) png_get_user_width_max(dummy_ptr));
   fprintf(STDERR, "  height_max = %lu\n",
-       (unsigned long) png_get_user_height_max(dummy_ptr));
+      (unsigned long) png_get_user_height_max(dummy_ptr));
   if (png_get_chunk_cache_max(dummy_ptr) == 0)
      fprintf(STDERR, "  cache_max  = unlimited\n");
   else
      fprintf(STDERR, "  cache_max  = %lu\n",
-          (unsigned long) png_get_chunk_cache_max(dummy_ptr));
+         (unsigned long) png_get_chunk_cache_max(dummy_ptr));
   if (png_get_chunk_malloc_max(dummy_ptr) == 0)
      fprintf(STDERR, "  malloc_max = unlimited\n");
   else
      fprintf(STDERR, "  malloc_max = %lu\n",
-          (unsigned long) png_get_chunk_malloc_max(dummy_ptr));
+         (unsigned long) png_get_chunk_malloc_max(dummy_ptr));
   png_destroy_read_struct(&dummy_ptr, NULL, NULL);

   return (int)(ierror != 0);
@@ -2081,11 +2063,11 @@ int
 main(void)
 {
   fprintf(STDERR,
-       " test ignored because libpng was not built with read support\n");
+      " test ignored because libpng was not built with read support\n");
   /* And skip this test */
-   return SKIP;
+   return PNG_LIBPNG_VER < 10600 ? 0 : 77;
 }
 #endif

 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_25 Your_png_h_is_not_version_1_6_25;
+typedef png_libpng_version_1_6_21 Your_png_h_is_not_version_1_6_21;
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -1,8 +1,8 @@

 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -172,14 +172,13 @@ png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
                   * size!
                   */
                  png_app_error(png_ptr,
-                      "png_set_filler is invalid for"
-                      " low bit depth gray output");
+                     "png_set_filler is invalid for low bit depth gray output");
                  return;
               }

            default:
               png_app_error(png_ptr,
-                   "png_set_filler: inappropriate color type");
+                  "png_set_filler: inappropriate color type");
               return;
         }
 #     else
@@ -798,7 +797,7 @@ png_set_user_transform_info(png_structrp png_ptr, png_voidp
      (png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
   {
      png_app_error(png_ptr,
-          "info change after png_start_read_image or png_read_update_info");
+            "info change after png_start_read_image or png_read_update_info");
      return;
   }
 #endif
--- a/pngwio.c
+++ b/pngwio.c
@@ -1,8 +1,8 @@

 /* pngwio.c - functions for data output
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -35,7 +35,7 @@ png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
   /* NOTE: write_data_fn must not change the buffer! */
   if (png_ptr->write_data_fn != NULL )
      (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
-          length);
+         length);

   else
      png_error(png_ptr, "Call to NULL write function");
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,8 +1,8 @@

 /* pngwrite.c - general routines to write a PNG file
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -12,9 +12,9 @@
 */

 #include "pngpriv.h"
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
+#if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
 #  include <errno.h>
-#endif /* SIMPLIFIED_WRITE_STDIO */
+#endif

 #ifdef PNG_WRITE_SUPPORTED

@@ -22,7 +22,7 @@
 /* Write out all the unknown chunks for the current given location */
 static void
 write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
-    unsigned int where)
+   unsigned int where)
 {
   if (info_ptr->unknown_chunks_num != 0)
   {
@@ -148,11 +148,11 @@ png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
 #    ifdef PNG_WRITE_sRGB_SUPPORTED
               if ((info_ptr->valid & PNG_INFO_sRGB) != 0)
                  png_app_warning(png_ptr,
-                      "profile matches sRGB but writing iCCP instead");
+                     "profile matches sRGB but writing iCCP instead");
 #     endif

            png_write_iCCP(png_ptr, info_ptr->iccp_name,
-                info_ptr->iccp_profile);
+               info_ptr->iccp_profile);
         }
 #     ifdef PNG_WRITE_sRGB_SUPPORTED
         else
@@ -383,7 +383,7 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr)
      for (i = 0; i < info_ptr->num_text; i++)
      {
         png_debug2(2, "Writing trailer text chunk %d, type %d", i,
-             info_ptr->text[i].compression);
+            info_ptr->text[i].compression);
         /* An internationalized chunk? */
         if (info_ptr->text[i].compression > 0)
         {
@@ -693,7 +693,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
      return;

   png_debug2(1, "in png_write_row (row %u, pass %d)",
-       png_ptr->row_number, png_ptr->pass);
+      png_ptr->row_number, png_ptr->pass);

   /* Initialize transformations and other stuff if first time */
   if (png_ptr->row_number == 0 && png_ptr->pass == 0)
@@ -1069,7 +1069,7 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
             * is not available so the filter can't be used.  Just warn here.
             */
            png_app_warning(png_ptr,
-                "png_set_filter: UP/AVG/PAETH cannot be added after start");
+               "png_set_filter: UP/AVG/PAETH cannot be added after start");
            filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
         }

@@ -1095,13 +1095,13 @@ png_set_filter(png_structrp png_ptr, int method, int filters)

         if (png_ptr->try_row == NULL)
            png_ptr->try_row = png_voidcast(png_bytep,
-                png_malloc(png_ptr, buf_size));
+               png_malloc(png_ptr, buf_size));

         if (num_filters > 1)
         {
            if (png_ptr->tst_row == NULL)
               png_ptr->tst_row = png_voidcast(png_bytep,
-                   png_malloc(png_ptr, buf_size));
+                  png_malloc(png_ptr, buf_size));
         }
      }
      png_ptr->do_filter = (png_byte)filters;
@@ -1452,6 +1452,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,


 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+# ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
 /* Initialize the write structure - general purpose utility. */
 static int
 png_image_write_init(png_imagep image)
@@ -1503,10 +1504,6 @@ typedef struct
   png_const_voidp first_row;
   ptrdiff_t       row_bytes;
   png_voidp       local_row;
-   /* Byte count for memory writing */
-   png_bytep        memory;
-   png_alloc_size_t memory_bytes; /* not used for STDIO */
-   png_alloc_size_t output_bytes; /* running total */
 } png_image_write_control;

 /* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
@@ -1628,7 +1625,7 @@ png_write_image_16bit(png_voidp argument)

 static png_byte
 png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
-    png_uint_32 reciprocal/*from the above macro*/)
+   png_uint_32 reciprocal/*from the above macro*/)
 {
   /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
    * is represented as some other value there is more likely to be a
@@ -1848,16 +1845,16 @@ png_image_set_PLTE(png_image_write_control *display)
            if (channels >= 3) /* RGB */
            {
               palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
-                   alpha, reciprocal);
+                  alpha, reciprocal);
               palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
-                   reciprocal);
+                  reciprocal);
               palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
-                   reciprocal);
+                  reciprocal);
            }

            else /* gray */
               palette[i].blue = palette[i].red = palette[i].green =
-                   png_unpremultiply(entry[afirst], alpha, reciprocal);
+                  png_unpremultiply(entry[afirst], alpha, reciprocal);
         }
      }

@@ -1904,11 +1901,11 @@ png_image_set_PLTE(png_image_write_control *display)
 #   endif

   png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
-       entries);
+      entries);

   if (num_trans > 0)
      png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
-          num_trans, NULL);
+         num_trans, NULL);

   image->colormap_entries = entries;
 }
@@ -1917,7 +1914,7 @@ static int
 png_image_write_main(png_voidp argument)
 {
   png_image_write_control *display = png_voidcast(png_image_write_control*,
-       argument);
+      argument);
   png_imagep image = display->image;
   png_structrp png_ptr = image->opaque->png_ptr;
   png_inforp info_ptr = image->opaque->info_ptr;
@@ -1934,43 +1931,9 @@ png_image_write_main(png_voidp argument)
      png_set_benign_errors(png_ptr, 0/*error*/);
 #   endif

-   /* Default the 'row_stride' parameter if required, also check the row stride
-    * and total image size to ensure that they are within the system limits.
-    */
-   {
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
-
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
-      {
-         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
-
-         if (display->row_stride == 0)
-            display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
-
-         if (display->row_stride < 0)
-            check = -display->row_stride;
-
-         else
-            check = display->row_stride;
-
-         if (check >= png_row_stride)
-         {
-            /* Now check for overflow of the image buffer calculation; this
-             * limits the whole image size to 32 bits for API compatibility with
-             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
-             */
-            if (image->height > 0xFFFFFFFF/png_row_stride)
-               png_error(image->opaque->png_ptr, "memory image too large");
-         }
-
-         else
-            png_error(image->opaque->png_ptr, "supplied row stride too small");
-      }
-
-      else
-         png_error(image->opaque->png_ptr, "image row stride too large");
-   }
+   /* Default the 'row_stride' parameter if required. */
+   if (display->row_stride == 0)
+      display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);

   /* Set the required transforms then write the rows in the correct order. */
   if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
@@ -1980,24 +1943,24 @@ png_image_write_main(png_voidp argument)
         png_uint_32 entries = image->colormap_entries;

         png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
-             entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
-             PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
-             PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+            entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
+            PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
+            PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

         png_image_set_PLTE(display);
      }

      else
         png_error(image->opaque->png_ptr,
-             "no color-map for color-mapped image");
+            "no color-map for color-mapped image");
   }

   else
      png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
-          write_16bit ? 16 : 8,
-          ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
-          ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
-          PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+         write_16bit ? 16 : 8,
+         ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
+         ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
+         PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

   /* Counter-intuitively the data transformations must be called *after*
    * png_write_info, not before as in the read code, but the 'set' functions
@@ -2012,11 +1975,11 @@ png_image_write_main(png_voidp argument)

      if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
         png_set_cHRM_fixed(png_ptr, info_ptr,
-             /* color      x       y */
-             /* white */ 31270, 32900,
-             /* red   */ 64000, 33000,
-             /* green */ 30000, 60000,
-             /* blue  */ 15000,  6000
+            /* color      x       y */
+            /* white */ 31270, 32900,
+            /* red   */ 64000, 33000,
+            /* green */ 30000, 60000,
+            /* blue  */ 15000,  6000
         );
   }

@@ -2110,7 +2073,7 @@ png_image_write_main(png_voidp argument)
       (colormap == 0 && display->convert_to_8bit != 0))
   {
      png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
-          png_get_rowbytes(png_ptr, info_ptr)));
+         png_get_rowbytes(png_ptr, info_ptr)));
      int result;

      display->local_row = row;
@@ -2147,130 +2110,14 @@ png_image_write_main(png_voidp argument)
   return 1;
 }

-
-static void (PNGCBAPI
-image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data,
-    png_size_t size)
-{
-   png_image_write_control *display = png_voidcast(png_image_write_control*,
-       png_ptr->io_ptr/*backdoor: png_get_io_ptr(png_ptr)*/);
-   const png_alloc_size_t ob = display->output_bytes;
-
-   /* Check for overflow; this should never happen: */
-   if (size <= ((png_alloc_size_t)-1) - ob)
-   {
-      /* I don't think libpng ever does this, but just in case: */
-      if (size > 0)
-      {
-         if (display->memory_bytes >= ob+size) /* writing */
-            memcpy(display->memory+ob, data, size);
-
-         /* Always update the size: */
-         display->output_bytes = ob+size;
-      }
-   }
-
-   else
-      png_error(png_ptr, "png_image_write_to_memory: PNG too big");
-}
-
-static void (PNGCBAPI
-image_memory_flush)(png_structp png_ptr)
-{
-   PNG_UNUSED(png_ptr)
-}
-
-static int
-png_image_write_memory(png_voidp argument)
-{
-   png_image_write_control *display = png_voidcast(png_image_write_control*,
-       argument);
-
-   /* The rest of the memory-specific init and write_main in an error protected
-    * environment.  This case needs to use callbacks for the write operations
-    * since libpng has no built in support for writing to memory.
-    */
-   png_set_write_fn(display->image->opaque->png_ptr, display/*io_ptr*/,
-       image_memory_write, image_memory_flush);
-
-   return png_image_write_main(display);
-}
-
-int PNGAPI
-png_image_write_to_memory(png_imagep image, void *memory,
-    png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8bit,
-    const void *buffer, png_int_32 row_stride, const void *colormap)
-{
-   /* Write the image to the given buffer, or count the bytes if it is NULL */
-   if (image != NULL && image->version == PNG_IMAGE_VERSION)
-   {
-      if (memory_bytes != NULL && buffer != NULL)
-      {
-         /* This is to give the caller an easier error detection in the NULL
-          * case and guard against uninitialized variable problems:
-          */
-         if (memory == NULL)
-            *memory_bytes = 0;
-
-         if (png_image_write_init(image) != 0)
-         {
-            png_image_write_control display;
-            int result;
-
-            memset(&display, 0, (sizeof display));
-            display.image = image;
-            display.buffer = buffer;
-            display.row_stride = row_stride;
-            display.colormap = colormap;
-            display.convert_to_8bit = convert_to_8bit;
-            display.memory = png_voidcast(png_bytep, memory);
-            display.memory_bytes = *memory_bytes;
-            display.output_bytes = 0;
-
-            result = png_safe_execute(image, png_image_write_memory, &display);
-            png_image_free(image);
-
-            /* write_memory returns true even if we ran out of buffer. */
-            if (result)
-            {
-               /* On out-of-buffer this function returns '0' but still updates
-                * memory_bytes:
-                */
-               if (memory != NULL && display.output_bytes > *memory_bytes)
-                  result = 0;
-
-               *memory_bytes = display.output_bytes;
-            }
-
-            return result;
-         }
-
-         else
-            return 0;
-      }
-
-      else
-         return png_image_error(image,
-             "png_image_write_to_memory: invalid argument");
-   }
-
-   else if (image != NULL)
-      return png_image_error(image,
-          "png_image_write_to_memory: incorrect PNG_IMAGE_VERSION");
-
-   else
-      return 0;
-}
-
-#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 int PNGAPI
 png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
-    const void *buffer, png_int_32 row_stride, const void *colormap)
+   const void *buffer, png_int_32 row_stride, const void *colormap)
 {
   /* Write the image to the given (FILE*). */
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      if (file != NULL && buffer != NULL)
+      if (file != NULL)
      {
         if (png_image_write_init(image) != 0)
         {
@@ -2301,12 +2148,12 @@ png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,

      else
         return png_image_error(image,
-             "png_image_write_to_stdio: invalid argument");
+            "png_image_write_to_stdio: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
+         "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");

   else
      return 0;
@@ -2314,20 +2161,20 @@ png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,

 int PNGAPI
 png_image_write_to_file(png_imagep image, const char *file_name,
-    int convert_to_8bit, const void *buffer, png_int_32 row_stride,
-    const void *colormap)
+   int convert_to_8bit, const void *buffer, png_int_32 row_stride,
+   const void *colormap)
 {
   /* Write the image to the named file. */
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
-      if (file_name != NULL && buffer != NULL)
+      if (file_name != NULL)
      {
         FILE *fp = fopen(file_name, "wb");

         if (fp != NULL)
         {
            if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
-                row_stride, colormap) != 0)
+               row_stride, colormap) != 0)
            {
               int error; /* from fflush/fclose */

@@ -2368,16 +2215,16 @@ png_image_write_to_file(png_imagep image, const char *file_name,

      else
         return png_image_error(image,
-             "png_image_write_to_file: invalid argument");
+            "png_image_write_to_file: invalid argument");
   }

   else if (image != NULL)
      return png_image_error(image,
-          "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
+         "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");

   else
      return 0;
 }
-#endif /* SIMPLIFIED_WRITE_STDIO */
+# endif /* STDIO */
 #endif /* SIMPLIFIED_WRITE */
 #endif /* WRITE */
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -1,8 +1,8 @@

 /* pngwtran.c - transforms the data in a row for PNG writers
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -525,7 +525,7 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 #ifdef PNG_WRITE_FILLER_SUPPORTED
   if ((png_ptr->transformations & PNG_FILLER) != 0)
      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-          !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
+         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
 #endif

 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
@@ -549,7 +549,7 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 #ifdef PNG_WRITE_SHIFT_SUPPORTED
   if ((png_ptr->transformations & PNG_SHIFT) != 0)
      png_do_shift(row_info, png_ptr->row_buf + 1,
-           &(png_ptr->shift));
+          &(png_ptr->shift));
 #endif

 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,8 +1,8 @@

 /* pngwutil.c - utilities to write a PNG file
 *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.21 [January 15, 2016]
+ * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
@@ -23,10 +23,10 @@
 void PNGAPI
 png_save_uint_32(png_bytep buf, png_uint_32 i)
 {
-   buf[0] = (png_byte)((i >> 24) & 0xffU);
-   buf[1] = (png_byte)((i >> 16) & 0xffU);
-   buf[2] = (png_byte)((i >>  8) & 0xffU);
-   buf[3] = (png_byte)( i        & 0xffU);
+   buf[0] = (png_byte)(i >> 24);
+   buf[1] = (png_byte)(i >> 16);
+   buf[2] = (png_byte)(i >> 8);
+   buf[3] = (png_byte)(i     );
 }

 /* Place a 16-bit number into a buffer in PNG byte order.
@@ -36,8 +36,8 @@ png_save_uint_32(png_bytep buf, png_uint_32 i)
 void PNGAPI
 png_save_uint_16(png_bytep buf, unsigned int i)
 {
-   buf[0] = (png_byte)((i >> 8) & 0xffU);
-   buf[1] = (png_byte)( i       & 0xffU);
+   buf[0] = (png_byte)(i >> 8);
+   buf[1] = (png_byte)(i     );
 }
 #endif

@@ -59,7 +59,7 @@ png_write_sig(png_structrp png_ptr)

   /* Write the rest of the 8 byte signature */
   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
-       (png_size_t)(8 - png_ptr->sig_bytes));
+      (png_size_t)(8 - png_ptr->sig_bytes));

   if (png_ptr->sig_bytes < 3)
      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
@@ -174,7 +174,7 @@ png_write_chunk_end(png_structrp png_ptr)
 */
 static void
 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
-    png_const_bytep data, png_size_t length)
+   png_const_bytep data, png_size_t length)
 {
   if (png_ptr == NULL)
      return;
@@ -191,10 +191,10 @@ png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
 /* This is the API that calls the internal function above. */
 void PNGAPI
 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
-    png_const_bytep data, png_size_t length)
+   png_const_bytep data, png_size_t length)
 {
   png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
-       length);
+      length);
 }

 /* This is used below to find the size of an image to pass to png_deflate_claim,
@@ -291,7 +291,7 @@ optimize_cmf(png_bytep data, png_alloc_size_t data_size)
 /* Initialize the compressor for the appropriate type of compression. */
 static int
 png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
-    png_alloc_size_t data_size)
+   png_alloc_size_t data_size)
 {
   if (png_ptr->zowner != 0)
   {
@@ -416,7 +416,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
      else
      {
         ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
-             memLevel, strategy);
+            memLevel, strategy);

         if (ret == Z_OK)
            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
@@ -477,7 +477,7 @@ typedef struct

 static void
 png_text_compress_init(compression_state *comp, png_const_bytep input,
-    png_alloc_size_t input_len)
+   png_alloc_size_t input_len)
 {
   comp->input = input;
   comp->input_len = input_len;
@@ -487,7 +487,7 @@ png_text_compress_init(compression_state *comp, png_const_bytep input,
 /* Compress the data in the compression state input */
 static int
 png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
-    compression_state *comp, png_uint_32 prefix_len)
+   compression_state *comp, png_uint_32 prefix_len)
 {
   int ret;

@@ -579,7 +579,7 @@ png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,

         /* Compress the data */
         ret = deflate(&png_ptr->zstream,
-             input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
+            input_len > 0 ? Z_NO_FLUSH : Z_FINISH);

         /* Claw back input data that was not consumed (because avail_in is
          * reset above every time round the loop).
@@ -925,7 +925,7 @@ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
 */
 void /* PRIVATE */
 png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
-    png_alloc_size_t input_len, int flush)
+   png_alloc_size_t input_len, int flush)
 {
   if (png_ptr->zowner != png_IDAT)
   {
@@ -937,7 +937,7 @@ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
      if (png_ptr->zbuffer_list == NULL)
      {
         png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
-             png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
+            png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
         png_ptr->zbuffer_list->next = NULL;
      }

@@ -1358,7 +1358,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,

      /* Write the chunk out as it is */
      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
-          (png_size_t)num_trans);
+         (png_size_t)num_trans);
   }

   else if (color_type == PNG_COLOR_TYPE_GRAY)
@@ -1389,7 +1389,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
 #endif
      {
         png_app_warning(png_ptr,
-             "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
+           "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
         return;
      }

@@ -1441,8 +1441,7 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
 #endif
      {
         png_warning(png_ptr,
-             "Ignoring attempt to write 16-bit bKGD chunk "
-             "when bit_depth is 8");
+             "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");

         return;
      }
@@ -1572,7 +1571,7 @@ png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,

   /* Compute the compressed data; do it now for the length */
   png_text_compress_init(&comp, (png_const_bytep)text,
-       text == NULL ? 0 : strlen(text));
+      text == NULL ? 0 : strlen(text));

   if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
      png_error(png_ptr, png_ptr->zstream.msg);
@@ -1942,7 +1941,7 @@ png_write_start_row(png_structrp png_ptr)
    */
   if ((filters & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0)
      png_ptr->prev_row = png_voidcast(png_bytep,
-          png_calloc(png_ptr, buf_size));
+         png_calloc(png_ptr, buf_size));
 #endif /* WRITE_FILTER */

 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
@@ -2245,7 +2244,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 */
 static void /* PRIVATE */
 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
-    png_size_t row_bytes);
+   png_size_t row_bytes);

 #ifdef PNG_WRITE_FILTER_SUPPORTED
 static png_size_t /* PRIVATE */
@@ -2263,22 +2262,14 @@ png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
        i++, rp++, dp++)
   {
      v = *dp = *rp;
-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif
   }

   for (lp = png_ptr->row_buf + 1; i < row_bytes;
      i++, rp++, lp++, dp++)
   {
      v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif

      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@@ -2287,28 +2278,6 @@ png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
   return (sum);
 }

-static void /* PRIVATE */
-png_setup_sub_row_only(png_structrp png_ptr, const png_uint_32 bpp,
-    const png_size_t row_bytes)
-{
-   png_bytep rp, dp, lp;
-   png_size_t i;
-
-   png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
-
-   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
-        i++, rp++, dp++)
-   {
-      *dp = *rp;
-   }
-
-   for (lp = png_ptr->row_buf + 1; i < row_bytes;
-      i++, rp++, lp++, dp++)
-   {
-      *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
-   }
-}
-
 static png_size_t /* PRIVATE */
 png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
    const png_size_t lmins)
@@ -2325,11 +2294,7 @@ png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
       i++, rp++, pp++, dp++)
   {
      v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif

      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@@ -2337,25 +2302,10 @@ png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,

   return (sum);
 }
-static void /* PRIVATE */
-png_setup_up_row_only(png_structrp png_ptr, const png_size_t row_bytes)
-{
-   png_bytep rp, dp, pp;
-   png_size_t i;
-
-   png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
-
-   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
-       pp = png_ptr->prev_row + 1; i < row_bytes;
-       i++, rp++, pp++, dp++)
-   {
-      *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
-   }
-}

 static png_size_t /* PRIVATE */
 png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
-    const png_size_t row_bytes, const png_size_t lmins)
+      const png_size_t row_bytes, const png_size_t lmins)
 {
   png_bytep rp, dp, pp, lp;
   png_uint_32 i;
@@ -2365,15 +2315,11 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
   png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;

   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
-       pp = png_ptr->prev_row + 1; i < bpp; i++)
+        pp = png_ptr->prev_row + 1; i < bpp; i++)
   {
      v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);

-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif
   }

   for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
@@ -2381,11 +2327,7 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
      v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
          & 0xff);

-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif

      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@@ -2393,27 +2335,6 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,

   return (sum);
 }
-static void /* PRIVATE */
-png_setup_avg_row_only(png_structrp png_ptr, const png_uint_32 bpp,
-    const png_size_t row_bytes)
-{
-   png_bytep rp, dp, pp, lp;
-   png_uint_32 i;
-
-   png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
-
-   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
-       pp = png_ptr->prev_row + 1; i < bpp; i++)
-   {
-      *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
-   }
-
-   for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
-   {
-      *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
-          & 0xff);
-   }
-}

 static png_size_t /* PRIVATE */
 png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
@@ -2431,11 +2352,7 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
   {
      v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);

-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif
   }

   for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
@@ -2464,11 +2381,7 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,

      v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);

-#ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
-#else
      sum += (v < 128) ? v : 256 - v;
-#endif

      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@@ -2476,48 +2389,6 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,

   return (sum);
 }
-static void /* PRIVATE */
-png_setup_paeth_row_only(png_structrp png_ptr, const png_uint_32 bpp,
-    const png_size_t row_bytes)
-{
-   png_bytep rp, dp, pp, cp, lp;
-   png_size_t i;
-
-   png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
-
-   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
-       pp = png_ptr->prev_row + 1; i < bpp; i++)
-   {
-      *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
-   }
-
-   for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
-        i++)
-   {
-      int a, b, c, pa, pb, pc, p;
-
-      b = *pp++;
-      c = *cp++;
-      a = *lp++;
-
-      p = b - c;
-      pc = a - c;
-
-#ifdef PNG_USE_ABS
-      pa = abs(p);
-      pb = abs(pc);
-      pc = abs(p + pc);
-#else
-      pa = p < 0 ? -p : p;
-      pb = pc < 0 ? -pc : pc;
-      pc = (p + pc) < 0 ? -(p + pc) : p + pc;
-#endif
-
-      p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
-
-      *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
-   }
-}
 #endif /* WRITE_FILTER */

 void /* PRIVATE */
@@ -2526,7 +2397,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 #ifndef PNG_WRITE_FILTER_SUPPORTED
   png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
 #else
-   unsigned int filter_to_do = png_ptr->do_filter;
+   png_byte filter_to_do = png_ptr->do_filter;
   png_bytep row_buf;
   png_bytep best_row;
   png_uint_32 bpp;
@@ -2572,33 +2443,32 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
    */
   best_row = png_ptr->row_buf;

-   if (PNG_SIZE_MAX/128 <= row_bytes)
+
+   if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
   {
-      /* Overflow can occur in the calculation, just select the lowest set
-       * filter.
-       */
-      filter_to_do &= 0U-filter_to_do;
-   }
-   else if ((filter_to_do & PNG_FILTER_NONE) != 0 &&
-         filter_to_do != PNG_FILTER_NONE)
-   {
-      /* Overflow not possible and multiple filters in the list, including the
-       * 'none' filter.
-       */
      png_bytep rp;
      png_size_t sum = 0;
      png_size_t i;
      int v;

+      if (PNG_SIZE_MAX/128 <= row_bytes)
+      {
+         for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
+         {
+            /* Check for overflow */
+            if (sum > PNG_SIZE_MAX/128 - 256)
+               break;
+
+            v = *rp;
+            sum += (v < 128) ? v : 256 - v;
+         }
+      }
+      else /* Overflow is not possible */
      {
         for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
         {
            v = *rp;
-#ifdef PNG_USE_ABS
-            sum += 128 - abs(v - 128);
-#else
            sum += (v < 128) ? v : 256 - v;
-#endif
         }
      }

@@ -2609,7 +2479,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   if (filter_to_do == PNG_FILTER_SUB)
   /* It's the only filter so no testing is needed */
   {
-      png_setup_sub_row_only(png_ptr, bpp, row_bytes);
+      (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins);
      best_row = png_ptr->try_row;
   }

@@ -2635,7 +2505,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   /* Up filter */
   if (filter_to_do == PNG_FILTER_UP)
   {
-      png_setup_up_row_only(png_ptr, row_bytes);
+      (void) png_setup_up_row(png_ptr, row_bytes, mins);
      best_row = png_ptr->try_row;
   }

@@ -2661,7 +2531,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   /* Avg filter */
   if (filter_to_do == PNG_FILTER_AVG)
   {
-      png_setup_avg_row_only(png_ptr, bpp, row_bytes);
+      (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins);
      best_row = png_ptr->try_row;
   }

@@ -2685,9 +2555,9 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   }

   /* Paeth filter */
-   if (filter_to_do == PNG_FILTER_PAETH)
+   if ((filter_to_do == PNG_FILTER_PAETH) != 0)
   {
-      png_setup_paeth_row_only(png_ptr, bpp, row_bytes);
+      (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins);
      best_row = png_ptr->try_row;
   }

@@ -2719,7 +2589,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 /* Do the actual writing of a previously filtered row. */
 static void
 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
-    png_size_t full_row_length/*includes filter byte*/)
+   png_size_t full_row_length/*includes filter byte*/)
 {
   png_debug(1, "in png_write_filtered_row");

--- a/projects/vstudio/README.txt
+++ b/projects/vstudio/README.txt
@@ -1,7 +1,7 @@

 VisualStudio instructions

-libpng version 1.6.25 - September 1, 2016
+libpng version 1.6.21 - January 15, 2016

 Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson

@@ -93,5 +93,3 @@ as follows:
    DLL               /MD         /MDd
    Static Library    /MD         /MDd

-Also, be sure to build libpng, zlib, and your project all for the same
-platform (e.g., 32-bit or 64-bit).
--- a/projects/vstudio/libpng/libpng.vcxproj
+++ b/projects/vstudio/libpng/libpng.vcxproj
@@ -84,7 +84,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PrecompiledHeader>Use</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
@@ -97,9 +97,9 @@
      <BrowseInformation>true</BrowseInformation>
      <CompileAs>CompileAsC</CompileAs>
      <StringPooling>true</StringPooling>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <Optimization>Disabled</Optimization>
      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
    </ClCompile>
@@ -114,7 +114,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
    <ClCompile>
      <PrecompiledHeader>Use</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
@@ -128,9 +128,9 @@
      <BrowseInformation>true</BrowseInformation>
      <CompileAs>CompileAsC</CompileAs>
      <StringPooling>true</StringPooling>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
    </ClCompile>
    <Link>
@@ -140,7 +140,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>Use</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <FunctionLevelLinking>true</FunctionLevelLinking>
@@ -153,9 +153,9 @@
      <CompileAs>CompileAsC</CompileAs>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <Optimization>Full</Optimization>
    </ClCompile>
    <Link>
@@ -170,7 +170,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>Use</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
@@ -184,9 +184,9 @@
      <CompileAs>CompileAsC</CompileAs>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <Optimization>Full</Optimization>
      <WholeProgramOptimization>true</WholeProgramOptimization>
    </ClCompile>
--- a/projects/vstudio/pnglibconf/pnglibconf.vcxproj
+++ b/projects/vstudio/pnglibconf/pnglibconf.vcxproj
@@ -30,7 +30,7 @@
  </PropertyGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level3</WarningLevel>
      <Optimization>MaxSpeed</Optimization>
      <FunctionLevelLinking>true</FunctionLevelLinking>
      <IntrinsicFunctions>true</IntrinsicFunctions>
--- a/projects/vstudio/pngstest/pngstest.vcxproj
+++ b/projects/vstudio/pngstest/pngstest.vcxproj
@@ -76,16 +76,16 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -109,7 +109,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
@@ -117,9 +117,9 @@
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -141,7 +141,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -149,9 +149,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
@@ -176,7 +176,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -185,9 +185,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
--- a/projects/vstudio/pngtest/pngtest.vcxproj
+++ b/projects/vstudio/pngtest/pngtest.vcxproj
@@ -76,16 +76,16 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -109,7 +109,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
@@ -117,9 +117,9 @@
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -141,7 +141,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -149,9 +149,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
@@ -176,7 +176,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -185,9 +185,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
--- a/projects/vstudio/pngunknown/pngunknown.vcxproj
+++ b/projects/vstudio/pngunknown/pngunknown.vcxproj
@@ -76,16 +76,16 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -109,7 +109,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
@@ -117,9 +117,9 @@
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -141,7 +141,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -149,9 +149,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
@@ -176,7 +176,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -185,9 +185,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
--- a/projects/vstudio/pngvalid/pngvalid.vcxproj
+++ b/projects/vstudio/pngvalid/pngvalid.vcxproj
@@ -76,16 +76,16 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -109,7 +109,7 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
    <ClCompile>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <MinimalRebuild>false</MinimalRebuild>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
@@ -117,9 +117,9 @@
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <StringPooling>true</StringPooling>
      <FunctionLevelLinking>false</FunctionLevelLinking>
@@ -141,7 +141,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -149,9 +149,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
@@ -176,7 +176,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level4</WarningLevel>
      <PrecompiledHeader>NotUsing</PrecompiledHeader>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
@@ -185,9 +185,9 @@
      <IntrinsicFunctions>true</IntrinsicFunctions>
      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings)</DisableSpecificWarnings>
+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
      <CompileAsManaged>false</CompileAsManaged>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <StringPooling>true</StringPooling>
      <MinimalRebuild>false</MinimalRebuild>
      <BrowseInformation>true</BrowseInformation>
--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
 * zlib.props - location of zlib source
 *
- * libpng version 1.6.25 - September 1, 2016
+ * libpng version 1.6.21 - January 15, 2016
 *
 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
 *
@@ -41,18 +41,5 @@
         test it:
     -->
    <WindowsSDKDesktopARMSupport>true</WindowsSDKDesktopARMSupport>
-
-    <!-- The following lines provide a global (solution level) control of the
-         warnings issued by the compiler, these are used in the individual
-         project files (*/*.vcxproj) with, for zlib, some extra disables.
-
-         Different versions of Visual Studio may require different settings,
-         these settings work with Visual Studio 2013.  Just set
-         TreatWarningAsError to false to check the build without failing on
-         errors.
-     -->
-   <WarningLevel>EnableAllWarnings</WarningLevel>
-   <TreatWarningAsError>true</TreatWarningAsError>
-   <DisableSpecificWarnings>4255;4668;4710;4711;4746;4820;4996</DisableSpecificWarnings>
  </PropertyGroup>
 </Project>
--- a/projects/vstudio/zlib/zlib.vcxproj
+++ b/projects/vstudio/zlib/zlib.vcxproj
@@ -88,13 +88,11 @@
    <ClCompile>
      <PreprocessorDefinitions>WIN32;_DEBUG;_WINDOWS;Z_SOLO;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>TurnOffAllWarnings</WarningLevel>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BrowseInformation>true</BrowseInformation>
      <FunctionLevelLinking>true</FunctionLevelLinking>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings);4127;4131;4242;4244</DisableSpecificWarnings>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
    </ClCompile>
    <Link>
      <TargetMachine>MachineX86</TargetMachine>
@@ -105,13 +103,11 @@
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
    <ClCompile>
      <PreprocessorDefinitions>WIN32;_DEBUG;_WINDOWS;Z_SOLO;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>TurnOffAllWarnings</WarningLevel>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Disabled</Optimization>
      <BrowseInformation>true</BrowseInformation>
      <FunctionLevelLinking>true</FunctionLevelLinking>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings);4127;4131;4242;4244</DisableSpecificWarnings>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
    </ClCompile>
    <Link>
@@ -122,7 +118,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level3</WarningLevel>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
      <IntrinsicFunctions>true</IntrinsicFunctions>
@@ -130,8 +126,7 @@
      <BufferSecurityCheck>false</BufferSecurityCheck>
      <BrowseInformation>true</BrowseInformation>
      <FunctionLevelLinking>true</FunctionLevelLinking>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings);4127;4131;4242;4244</DisableSpecificWarnings>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
      <PreprocessorDefinitions>WIN32;NDEBUG;_WINDOWS;Z_SOLO;%(PreprocessorDefinitions)</PreprocessorDefinitions>
    </ClCompile>
@@ -146,7 +141,7 @@
  </ItemDefinitionGroup>
  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
    <ClCompile>
-      <WarningLevel>$(WarningLevel)</WarningLevel>
+      <WarningLevel>Level3</WarningLevel>
      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
      <Optimization>Full</Optimization>
      <IntrinsicFunctions>true</IntrinsicFunctions>
@@ -154,8 +149,7 @@
      <BufferSecurityCheck>false</BufferSecurityCheck>
      <BrowseInformation>true</BrowseInformation>
      <FunctionLevelLinking>true</FunctionLevelLinking>
-      <DisableSpecificWarnings>$(DisableSpecificWarnings);4127;4131;4242;4244</DisableSpecificWarnings>
-      <TreatWarningAsError>$(TreatWarningAsError)</TreatWarningAsError>
+      <TreatWarningAsError>true</TreatWarningAsError>
      <PreprocessorDefinitions>WIN32;NDEBUG;_WINDOWS;Z_SOLO;%(PreprocessorDefinitions)</PreprocessorDefinitions>
    </ClCompile>
    <Link>
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@

-Makefiles for  libpng version 1.6.25 - September 1, 2016
+Makefiles for  libpng version 1.6.21 - January 15, 2016

 pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.25)
+                       (gcc, creates libpng16.so.16.1.6.21)
 makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
 makefile.knr      =>  Archaic UNIX Makefile that converts files with
                       ansi2knr (Requires ansi2knr.c from
@@ -33,12 +33,12 @@ pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.os2      =>  OS/2 Makefile (gcc and emx, requires libpng.def)
 makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
 makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.21)
 makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
 makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.21)
 makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.21)
 makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
 makefile.sunos    =>  Sun makefile
 makefile.32sunu   =>  Sun Ultra 32-bit makefile
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@ PNG_DFN "OS2 DESCRIPTION "PNG image compression library""
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.25"
+PNG_DFN ";Version 1.6.21"

 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
        PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
--- a/scripts/genchk.cmake.in
+++ b/scripts/genchk.cmake.in
@@ -1,37 +0,0 @@
-# genchk.cmake.in
-# Generate .chk from .out with awk (generic), based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-
-set(AWK "@AWK@")
-
-get_filename_component(INPUTEXT "${INPUT}" EXT)
-get_filename_component(OUTPUTEXT "${OUTPUT}" EXT)
-get_filename_component(INPUTBASE "${INPUT}" NAME_WE)
-get_filename_component(OUTPUTBASE "${OUTPUT}" NAME_WE)
-get_filename_component(INPUTDIR "${INPUT}" PATH)
-get_filename_component(OUTPUTDIR "${OUTPUT}" PATH)
-
-if("${INPUTEXT}" STREQUAL ".out" AND "${OUTPUTEXT}" STREQUAL ".chk")
-  # Generate .chk from .out with awk (generic)
-  file(REMOVE "${OUTPUT}" "${OUTPUTDIR}/${OUTPUTBASE}.new")
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/checksym.awk"
-                          "${SRCDIR}/scripts/${INPUTBASE}.def"
-                          "of=${OUTPUTDIR}/${OUTPUTBASE}.new"
-                          "${INPUT}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUTDIR}/${OUTPUTBASE}.new")
-  endif()
-  file(RENAME "${OUTPUTDIR}/${OUTPUTBASE}.new" "${OUTPUT}")
-else()
-  message(FATAL_ERROR "Unsupported conversion: ${INPUTEXT} to ${OUTPUTEXT}")
-endif()
--- a/scripts/genout.cmake.in
+++ b/scripts/genout.cmake.in
@@ -1,93 +0,0 @@
-# genout.cmake.in
-# Generate .out from .c with awk (generic), based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-set(BINDIR "@CMAKE_CURRENT_BINARY_DIR@")
-
-set(AWK "@AWK@")
-set(CMAKE_C_COMPILER "@CMAKE_C_COMPILER@")
-set(CMAKE_C_FLAGS @CMAKE_C_FLAGS@)
-set(INCDIR "@CMAKE_CURRENT_BINARY_DIR@")
-set(PNG_PREFIX "@PNG_PREFIX@")
-set(PNGLIB_MAJOR "@PNGLIB_MAJOR@")
-set(PNGLIB_MINOR "@PNGLIB_MINOR@")
-set(PNGLIB_VERSION "@PNGLIB_VERSION@")
-set(ZLIBINCDIR "@ZLIB_INCLUDE_DIR@")
-
-set(PLATFORM_C_FLAGS)
-if(APPLE)
-  set(CMAKE_OSX_ARCHITECTURES "@CMAKE_OSX_ARCHITECTURES@")
-  set(CMAKE_OSX_SYSROOT "@CMAKE_OSX_SYSROOT@")
-  if(CMAKE_OSX_ARCHITECTURES)
-    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -arch ${CMAKE_OSX_ARCHITECTURES})
-  endif()
-  if(CMAKE_OSX_SYSROOT)
-    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -isysroot ${CMAKE_OSX_SYSROOT})
-  endif()
-endif()
-
-get_filename_component(INPUTEXT "${INPUT}" EXT)
-get_filename_component(OUTPUTEXT "${OUTPUT}" EXT)
-get_filename_component(INPUTBASE "${INPUT}" NAME_WE)
-get_filename_component(OUTPUTBASE "${OUTPUT}" NAME_WE)
-get_filename_component(INPUTDIR "${INPUT}" PATH)
-get_filename_component(OUTPUTDIR "${OUTPUT}" PATH)
-
-if ("${INPUTEXT}" STREQUAL ".c" AND "${OUTPUTEXT}" STREQUAL ".out")
-  get_filename_component(GENDIR "${OUTPUT}" PATH)
-  file(MAKE_DIRECTORY "${GENDIR}")
-
-  file(REMOVE "${OUTPUT}.tf1" "${OUTPUT}.tf2")
-
-  set(INCLUDES "-I${INCDIR}")
-  if(ZLIBINCDIR)
-    foreach(dir ${ZLIBINCDIR})
-      list(APPEND INCLUDES "-I${dir}")
-    endforeach()
-  endif()
-
-  if(PNG_PREFIX)
-    set(PNG_PREFIX_DEF "-DPNG_PREFIX=${PNG_PREFIX}")
-  endif()
-
-  execute_process(COMMAND "${CMAKE_C_COMPILER}" "-E"
-                          ${CMAKE_C_FLAGS}
-                          ${PLATFORM_C_FLAGS}
-                          "-I${SRCDIR}"
-                          "-I${BINDIR}"
-                          ${INCLUDES}
-                          "-DPNGLIB_LIBNAME=PNG${PNGLIB_MAJOR}${PNGLIB_MINOR}_0"
-                          "-DPNGLIB_VERSION=${PNGLIB_VERSION}"
-                          "-DSYMBOL_PREFIX=${SYMBOL_PREFIX}"
-                          "-DPNG_NO_USE_READ_MACROS"
-                          "-DPNG_BUILDING_SYMBOL_TABLE"
-                          ${PNG_PREFIX_DEF}
-                          "${INPUT}"
-                  OUTPUT_FILE "${OUTPUT}.tf1"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE CPP_FAIL)
-  if(CPP_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUT}.tf1")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/dfn.awk"
-                          "out=${OUTPUT}.tf2" "${OUTPUT}.tf1"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate ${OUTPUT}.tf2")
-  endif()
-
-  file(REMOVE "${OUTPUT}.tf1")
-  file(RENAME "${OUTPUT}.tf2" "${OUTPUT}")
-else()
-  message(FATAL_ERROR "Unsupported conversion: ${INPUTEXT} to ${OUTPUTEXT}")
-endif()
--- a/scripts/gensrc.cmake.in
+++ b/scripts/gensrc.cmake.in
@@ -1,138 +0,0 @@
-# gensrc.cmake.in
-# Generate source files with awk, based upon the automake logic.
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-# Variables substituted from CMakeLists.txt
-set(SRCDIR "@CMAKE_CURRENT_SOURCE_DIR@")
-set(BINDIR "@CMAKE_CURRENT_BINARY_DIR@")
-
-set(AWK "@AWK@")
-set(DFA_XTRA "@DFA_XTRA@")
-set(PNG_PREFIX "@PNG_PREFIX@")
-set(PNGLIB_VERSION "@PNGLIB_VERSION@")
-
-if("${OUTPUT}" STREQUAL "scripts/pnglibconf.c")
-  # Generate scripts/pnglibconf.c
-
-  file(REMOVE "${BINDIR}/pnglibconf.tf6" "${BINDIR}/pnglibconf.tf7")
-
-  execute_process(COMMAND "${CMAKE_COMMAND}" -E echo "com ${PNGLIB_VERSION} STANDARD API DEFINITION"
-                  COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                          "out=pnglibconf.tf6" "logunsupported=1" "version=search"
-                          "${SRCDIR}/pngconf.h" "-"
-                          "${SRCDIR}/scripts/pnglibconf.dfa"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf6")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  "out=pnglibconf.tf7" "pnglibconf.tf6"
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf7")
-  endif()
-
-  file(REMOVE "pnglibconf.tf6")
-  file(MAKE_DIRECTORY "${BINDIR}/scripts")
-  file(RENAME "pnglibconf.tf7" "${BINDIR}/scripts/pnglibconf.c")
-
-elseif ("${OUTPUT}" STREQUAL "pnglibconf.c")
-  # Generate pnglibconf.c
-
-  file(REMOVE "${BINDIR}/pnglibconf.tf4" "${BINDIR}/pnglibconf.tf5")
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  out=pnglibconf.tf4 version=search
-                  ${SRCDIR}/pngconf.h ${SRCDIR}/scripts/pnglibconf.dfa
-                  ${SRCDIR}/pngusr.dfa ${DFA_XTRA}
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf4")
-  endif()
-
-  execute_process(COMMAND "${AWK}" -f "${SRCDIR}/scripts/options.awk"
-                  out=pnglibconf.tf5 pnglibconf.tf4
-                  WORKING_DIRECTORY "${BINDIR}"
-                  RESULT_VARIABLE AWK_FAIL)
-  if(AWK_FAIL)
-    message(FATAL_ERROR "Failed to generate pnglibconf.tf5")
-  endif()
-
-  file(REMOVE "pnglibconf.tf4")
-  file(MAKE_DIRECTORY "${BINDIR}/scripts")
-  file(RENAME "pnglibconf.tf5" "${BINDIR}/pnglibconf.c")
-
-elseif ("${OUTPUT}" STREQUAL "pnglibconf.h")
-  # Generate pnglibconf.h
-
-  file(REMOVE "${BINDIR}/${OUTPUT}")
-  if(PNG_PREFIX)
-    file(REMOVE "pnglibconf.tf8")
-
-    execute_process(COMMAND "${AWK}" "s==0 && NR>1{print prev}
-                             s==0{prev=\$0}
-                             s==1{print \"#define\", \$1, \"${PNG_PREFIX}\" \$1}
-                             s==2{print \"#define ${PNG_PREFIX}png_\" \$1, \"PNG_\" \$1}
-                             END{print prev}" s=0 pnglibconf.out s=1 "${BINDIR}/scripts/prefix.out"
-                             s=2 "${SRCDIR}/scripts/macro.lst"
-                    OUTPUT_FILE pnglibconf.tf8
-                    RESULT_VARIABLE AWK_FAIL)
-    if(AWK_FAIL)
-      message(FATAL_ERROR "Failed to generate pnglibconf.tf8")
-    endif()
-
-    file(RENAME "pnglibconf.tf8" "${BINDIR}/${OUTPUT}")
-  else()
-    execute_process(COMMAND "${CMAKE_COMMAND}" -E copy "${BINDIR}/pnglibconf.out"
-                                                       "${BINDIR}/${OUTPUT}"
-                    RESULT_VARIABLE COPY_FAIL)
-    if(COPY_FAIL)
-      message(FATAL_ERROR "Failed to create pnglibconf.h")
-    endif()
-  endif()
-
-elseif ("${OUTPUT}" STREQUAL "pngprefix.h")
-  # Generate pngprefix.h
-
-  file(REMOVE "${BINDIR}/${OUTPUT}")
-
-  if(PNG_PREFIX)
-    file(REMOVE "pngprefix.tf1")
-
-    execute_process(COMMAND "${AWK}"
-                            "{print \"#define\", \$1, \"${PNG_PREFIX}\" \$1}"
-                            "${BINDIR}/scripts/intprefix.out"
-                    OUTPUT_FILE "pngprefix.tf1"
-                    RESULT_VARIABLE AWK_FAIL)
-    if(AWK_FAIL)
-      message(FATAL_ERROR "Failed to generate pngprefix.tf1")
-    endif()
-
-    file(RENAME "pngprefix.tf1" "${BINDIR}/${OUTPUT}")
-  else()
-    file(WRITE "${BINDIR}/${OUTPUT}" "/* No libpng symbol prefix configured. */")
-  endif()
-
-elseif("${OUTPUT}" STREQUAL "scripts/pnglibconf.h.prebuilt")
-  # Generate scripts/pnglibconf.h.prebuilt (fails build)
-
-  message(STATUS "Attempting to build scripts/pnglibconf.h.prebuilt")
-  message(STATUS "This is a machine generated file, but if you want to make")
-  message(STATUS "a new one simply build the 'genfiles' target, and copy")
-  message(STATUS "scripts/pnglibconf.out to scripts/pnglibconf.h.prebuilt")
-  message(STATUS "AND set PNG_ZLIB_VERNUM to 0 (you MUST do this)")
-  message(FATAL_ERROR "Stopping build")
-
-else()
-  message(FATAL_ERROR "Unsupported output: ${OUTPUT}")
-endif()
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@

 # Modeled after libxml-config.

-version=1.6.25
+version=1.6.21
 prefix=""
 libdir=""
 libs=""
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng16

 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.25
+Version: 1.6.21
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@

 VERMAJ = 1
 VERMIN = 6
-VERMIC = 25
+VERMIC = 21
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 25
+RELEASE = 21

 # Shared library names:
 LIBSO=$(LIBNAME).so
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@ exec_prefix=$(prefix)
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 25
+RELEASE = 21

 # Shared library names:
 LIBSO=$(LIBNAME).dll
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16

 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.21
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include

 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.21
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat

 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.21

 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
--- a/scripts/pnglibconf.dfa
+++ b/scripts/pnglibconf.dfa
@@ -552,7 +552,6 @@ option WRITE_ANCILLARY_CHUNKS requires WRITE

 # These options disable *all* the text chunks if turned off

-option TEXT disabled
 option READ_TEXT requires READ_ANCILLARY_CHUNKS enables TEXT
 option WRITE_TEXT requires WRITE_ANCILLARY_CHUNKS enables TEXT

@@ -874,12 +873,9 @@ option SIMPLIFIED_READ_BGR enables FORMAT_BGR,

 # Write:
 option SIMPLIFIED_WRITE,
-   requires WRITE, SETJMP, WRITE_SWAP, WRITE_PACK,
+   requires WRITE STDIO, SETJMP, WRITE_SWAP, WRITE_PACK,
      WRITE_tRNS, WRITE_gAMA, WRITE_sRGB, WRITE_cHRM

-# 1.6.22: allow simplified write without stdio support:
-option SIMPLIFIED_WRITE_STDIO requires SIMPLIFIED_WRITE STDIO
-
 option SIMPLIFIED_WRITE_AFIRST enables FORMAT_AFIRST,
   requires SIMPLIFIED_WRITE WRITE_SWAP_ALPHA

--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.25 STANDARD API DEFINITION */
+/* libpng 1.6.21 STANDARD API DEFINITION */

 /* pnglibconf.h - library build configuration */

-/* Libpng version 1.6.25 - September 1, 2016 */
+/* Libpng version 1.6.21 - January 15, 2016 */

 /* Copyright (c) 1998-2015 Glenn Randers-Pehrson */

@@ -109,7 +109,6 @@
 #define PNG_SIMPLIFIED_READ_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
-#define PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
 #define PNG_SIMPLIFIED_WRITE_SUPPORTED
 #define PNG_STDIO_SUPPORTED
 #define PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.25
+;Version 1.6.21
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng
@@ -249,4 +249,3 @@ EXPORTS
 png_set_check_for_invalid_index @242
 png_get_palette_max @243
 png_set_option @244
- png_image_write_to_memory @245
--- a/scripts/test.cmake.in
+++ b/scripts/test.cmake.in
@@ -1,31 +0,0 @@
-# test.cmake.in
-
-# Copyright (C) 2016 Glenn Randers-Pehrson
-# Written by Roger Leigh, 2016
-
-# This code is released under the libpng license.
-# For conditions of distribution and use, see the disclaimer
-# and license in png.h
-
-set(TEST_OPTIONS "@TEST_OPTIONS@")
-set(TEST_FILES "@TEST_FILES@")
-
-foreach(file ${TEST_FILES})
-  file(TO_NATIVE_PATH "${file}" native_file)
-  list(APPEND NATIVE_TEST_FILES "${native_file}")
-endforeach()
-
-# Add the directory containing libpng to the PATH (Windows only)
-if(WIN32)
-  get_filename_component(LIBPNG_DIR "${LIBPNG}" PATH)
-  file(TO_NATIVE_PATH "${LIBPNG_DIR}" LIBPNG_DIR)
-  set(ENV{PATH} "${LIBPNG_DIR};$ENV{PATH}")
-endif()
-
-execute_process(COMMAND "${CMAKE_COMMAND}" -E echo "Running ${TEST_COMMAND}" ${TEST_OPTIONS} ${NATIVE_TEST_FILES})
-
-execute_process(COMMAND "${TEST_COMMAND}" ${TEST_OPTIONS} ${NATIVE_TEST_FILES}
-                RESULT_VARIABLE TEST_STATUS)
-if(TEST_STATUS)
-  message(FATAL_ERROR "Returned failed status ${TEST_STATUS}!")
-endif()
--- a/tests/pngstest
+++ b/tests/pngstest
@@ -17,38 +17,36 @@ gamma="$1"
 shift
 alpha="$1"
 shift
-args=
-LC_ALL="C" # fix glob sort order to ASCII:
-for f in "${srcdir}/contrib/testpngs/"*.png
-do
-   g=
-   case "$f" in
-      *-linear[.-]*)
-         test "$gamma" = "linear" && g="$f";;
+exec ./pngstest --tmpfile "${gamma}-${alpha}-" --log ${1+"$@"} `
+   for f in "${srcdir}/contrib/testpngs/"*.png
+   do
+      g=
+      case "$f" in
+         *-linear[.-]*)
+            test "$gamma" = "linear" && g="$f";;

-      *-sRGB[.-]*)
-         test "$gamma" = "sRGB" && g="$f";;
+         *-sRGB[.-]*)
+            test "$gamma" = "sRGB" && g="$f";;

-      *-1.8[.-]*)
-         test "$gamma" = "1.8" && g="$f";;
+         *-1.8[.-]*)
+            test "$gamma" = "1.8" && g="$f";;

-      *)
-         test "$gamma" = "none" && g="$f";;
-   esac
+         *)
+            test "$gamma" = "none" && g="$f";;
+      esac

-   case "$g" in
-      "")
-         :;;
+      case "$g" in
+         "")
+            :;;

-      *-alpha[-.]*)
-         test "$alpha" = "alpha" && args="$args $g";;
+         *-alpha[-.]*)
+            test "$alpha" = "alpha" && echo "$g";;

-      *-tRNS[-.]*)
-         test "$alpha" = "tRNS" -o "$alpha" = "none" && args="$args $g";;
+         *-tRNS[-.]*)
+            test "$alpha" = "tRNS" -o "$alpha" = "none" && echo "$g";;

-      *)
-         test "$alpha" = "opaque" -o "$alpha" = "none" && args="$args $g";;
-   esac
-done
-# This only works if the arguments don't contain spaces; they don't.
-exec ./pngstest --tmpfile "${gamma}-${alpha}-" --log ${1+"$@"} $args
+         *)
+            test "$alpha" = "opaque" -o "$alpha" = "none" && echo "$g";;
+      esac
+   done
+`