[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
148 changed files with 2433 additions and 12600 deletions
--- a/47
+++ b/47
@@ -1,4 +1,4 @@
-Libpng 1.6.34 - September 29, 2017
+Libpng 1.6.21 - January 15, 2016

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

@@ -7,24 +7,49 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   libpng-1.6.34.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.34.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

-   lpng1634.7z  (LZMA-compressed, recommended)
-   lpng1634.zip
+   /scratch/glennrp/Libpng16/lpng1621.7z  (LZMA-compressed, recommended)
+   /scratch/glennrp/Libpng16/lpng1621.zip

 Other information:

-   libpng-1.6.34-README.txt
-   libpng-1.6.34-LICENSE.txt
-   libpng-1.6.34-*.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 (1.6.33):
-  Removed contrib/pngsuite/i*.png; some of these were incorrect and caused
-    test failures.
+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
--- a/563
+++ b/563
@@ -593,7 +593,7 @@ Version 1.0.5e [November 30, 1999]
    with trailing compressed parts easier in the future, and added new functions
    png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,
    png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).
-    NOTE: Applications that write text chunks MUST define png_text->lang
+  NOTE: Applications that write text chunks MUST define png_text->lang
    before calling png_set_text(). It must be set to NULL if you want to
    write tEXt or zTXt chunks.  If you want your application to be able to
    run with older versions of libpng, use
@@ -833,7 +833,7 @@ Version 1.0.7beta11 [May 7, 2000]
  Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
    which are no longer used.
  Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
-    defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXt_SUPPORTED
+    defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
    is defined.
  Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
    overrun when old applications fill the info_ptr->text structure directly.
@@ -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
@@ -5485,562 +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.
-
-Version 1.6.26beta01 [September 26, 2016]
-  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
-    bugfix by John Bowler).
-  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
-    has allocated memory that libpng needs to free.
-  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
-  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
-    while decoding compressed data chunks.
-  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
-    pngrutil.c.
-  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
-    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
-  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
-  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
-  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
-
-Version 1.6.26beta02 [October 1, 2016]
-  Updated the documentation about CRC and ADLER32 handling.
-  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
-     pngwrite.c, pngunknown.c, and pngvalid.c.
-  Quieted 58 (out of 144) -Wconversion compiler warnings by changing
-    flag definitions in pngpriv.h from 0xnnnn to 0xnnnnU and trivial changes
-    in png.c, pngread.c, and pngwutil.c.
-
-Version 1.6.26beta03 [October 2, 2016]
-  Removed contrib/libtests/*.orig and *.rej that slipped into the tarballs.
-  Quieted the 86 remaining -Wconversion compiler warnings by
-    revising the png_isaligned() macro and trivial changes in png.c,
-    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
-    pngwtran.c, pngwrite.c, and pngwutil.c.
-
-Version 1.6.26beta04 [October 3, 2016]
-  Quieted (bogus?) clang warnings about "absolute value has no effect"
-    when PNG_USE_ABS is defined.
-  Fixed offsets in contrib/intel/intel_sse.patch
-
-Version 1.6.26beta05 [October 6, 2016]
-  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
-    to avoid a signed/unsigned compare in the preprocessor.
-
-Version 1.6.26beta06 [October 7, 2016]
-  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
-    optionally avoid ADLER32 evaluation.
-
-Version 1.6.26rc01 [October 12, 2016]
-  No changes.
-
-Version 1.6.26 [October 20, 2016]
-  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
-  Despammed email addresses (replaced "@" with " at ").
-
-Version 1.6.27beta01 [November 2, 2016]
-  Restrict the new ADLER32-skipping to IDAT chunks.  It broke iCCP chunk
-    handling: an erroneous iCCP chunk would throw a png_error and reject the
-    entire PNG image instead of rejecting just the iCCP chunk with a warning,
-    if built with zlib-1.2.8.1.
-
-Version 1.6.27rc01 [December 27, 2016]
-  Control ADLER32 checking with new PNG_IGNORE_ADLER32 option. Fixes
-    an endless loop when handling erroneous ADLER32 checksums; bug
-    introduced in libpng-1.6.26.
-  Removed the use of a macro containing the pre-processor 'defined'
-    operator.  It is unclear whether this is valid; a macro that
-    "generates" 'defined' is not permitted, but the use of the word
-    "generates" within the C90 standard seems to imply more than simple
-    substitution of an expression itself containing a well-formed defined
-    operation.
-  Added ARM support to CMakeLists.txt (Andreas Franek).
-
-Version 1.6.27 [December 29, 2016]
-  Fixed a potential null pointer dereference in png_set_text_2() (bug report
-    and patch by Patrick Keshishian, CVE-2016-10087).
-
-Version 1.6.28rc01 [January 3, 2017]
-  Fixed arm/aarch64 detection in CMakeLists.txt (Gianfranco Costamagna).
-  Added option to Cmake build allowing a custom location of zlib to be
-    specified in a scenario where libpng is being built as a subproject
-    alongside zlib by another project (Sam Serrels).
-  Changed png_ptr->options from a png_byte to png_uint_32, to accomodate
-    up to 16 options.
-
-Version 1.6.28rc02 [January 4, 2017]
-  Added "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
-  Moved SSE2 optimization code into the main libpng source directory.
-    Configure libpng with "configure --enable-intel-sse" or compile
-    libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
-
-Version 1.6.28rc03 [January 4, 2017]
-  Backed out the SSE optimization and last CMakeLists.txt to allow time for QA.
-
-Version 1.6.28 [January 5, 2017]
-  No changes.
-
-Version 1.6.29beta01 [January 12, 2017]
-  Readded "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
-  Moved SSE2 optimization code into the main libpng source directory.
-    Configure libpng with "configure --enable-intel-sse" or compile
-    libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
-  Simplified conditional compilation in pngvalid.c, for AIX (Michael Felt).
-
-Version 1.6.29beta02 [February 22, 2017]
-  Avoid conditional directives that break statements in pngrutil.c (Romero
-    Malaquias)
-  The contrib/examples/pngtopng.c recovery code was in the wrong "if"
-    branches; the comments were correct.
-  Added code for PowerPC VSX optimisation (Vadim Barkov).
-
-Version 1.6.29beta03 [March 1, 2017]
-  Avoid potential overflow of shift operations in png_do_expand() (Aaron Boxer).
-  Change test ZLIB_VERNUM >= 0x1281 to ZLIB_VERNUM >= 0x1290 in pngrutil.c
-    because Solaris 11 distributes zlib-1.2.8.f that is older than 1.2.8.1,
-    as suggested in zlib FAQ, item 24.
-  Suppress clang warnings about implicit sign changes in png.c
-
-Version 1.6.29 [March 16, 2017]
-  No changes.
-
-Version 1.6.30beta01 [April 1, 2017]
-  Added missing "$(CPPFLAGS)" to the compile line for c.pic.o in
-    makefile.linux and makefile.solaris-x86 (Cosmin).
-  Revised documentation of png_get_error_ptr() in the libpng manual.
-  Silence clang -Wcomma and const drop warnings (Viktor Szakats).
-  Update Sourceforge URLs in documentation (https instead of http).
-
-Version 1.6.30beta02 [April 22, 2017]
-  Document need to check for integer overflow when allocating a pixel
-    buffer for multiple rows in contrib/gregbook, contrib/pngminus,
-    example.c, and in the manual (suggested by Jaeseung Choi). This
-    is similar to the bug reported against pngquant in CVE-2016-5735.
-  Removed reference to the obsolete PNG_SAFE_LIMITS macro in the documentation.
-
-Version 1.6.30beta03 [May 22, 2017]
-  Check for integer overflow in contrib/visupng and contrib/tools/genpng.
-  Do not double evaluate CMAKE_SYSTEM_PROCESSOR in CMakeLists.txt.
-  Test CMAKE_HOST_WIN32 instead of WIN32 in CMakeLists.txt.
-  Fix some URL in documentation.
-
-Version 1.6.30beta04 [June 7, 2017]
-  Avoid writing an empty IDAT when the last IDAT exactly fills the
-    compression buffer (bug report by Brian Baird). This bug was
-    introduced in libpng-1.6.0.
-
-Version 1.6.30rc01 [June 14, 2017]
-  No changes.
-
-Version 1.6.30rc02 [June 25, 2017]
-  Update copyright year in pnglibconf.h, make ltmain.sh executable.
-  Add a reference to the libpng.download site in README.
-
-Version 1.6.30 [June 28, 2017]
-  No changes.
-
-Version 1.6.31beta01 [July 5, 2017]
-  Guard the definition of _POSIX_SOURCE in pngpriv.h (AIX already defines it;
-    bug report by Michael Felt).
-  Revised pngpriv.h to work around failure to compile arm/filter_neon.S
-    ("typedef" directive is unrecognized by the assembler). The problem
-    was introduced in libpng-1.6.30beta01.
-  Added "Requires: zlib" to libpng.pc.in (Pieter Neerincx).
-  Added special case for FreeBSD in arm/filter_neon.S (Maya Rashish).
-
-Version 1.6.31beta02 [July 8, 2017]
-  Added instructions for disabling hardware optimizations in INSTALL.
-  Added "--enable-hardware-optimizations" configuration flag to enable
-    or disable all hardware optimizations with one flag.
-
-Version 1.6.31beta03 [July 9, 2017]
-  Updated CMakeLists.txt to add INTEL_SSE and MIPS_MSA platforms.
-  Changed "int" to "png_size_t" in intel/filter_sse2.c to prevent
-    possible integer overflow (Bug report by John Bowler).
-  Quieted "declaration after statement" warnings in intel/filter_sse2.c.
-  Added scripts/makefile-linux-opt, which has hardware optimizations enabled.
-
-Version 1.6.31beta04 [July 11, 2017]
-  Removed one of the GCC-7.1.0 'strict-overflow' warnings that result when
-    integers appear on both sides of a compare.  Worked around the others by
-    forcing the strict-overflow setting in the relevant functions to a level
-    where they are not reported (John Bowler).
-  Changed "FALL THROUGH" comments to "FALLTHROUGH" because GCC doesn't like
-    the space.
-  Worked around some C-style casts from (void*) because g++ 5.4.0 objects
-    to them.
-  Increased the buffer size for 'sprint' to pass the gcc 7.1.0 'sprint
-    overflow' check that is on by default with -Wall -Wextra.
-
-Version 1.6.31beta05 [July 13, 2017]
-  Added eXIf chunk support.
-
-Version 1.6.31beta06 [July 17, 2017]
-  Added a minimal eXIf chunk (with Orientation and FocalLengthIn35mmFilm
-    tags) to pngtest.png.
-
-Version 1.6.31beta07 [July 18, 2017]
-  Revised the eXIf chunk in pngtest.png to fix "Bad IFD1 Directory" warning.
-
-Version 1.6.31rc01 [July 19, 2017]
-  No changes.
-
-Version 1.6.31rc02 [July 25, 2017]
-  Fixed typo in example.c (png_free_image should be png_image_free) (Bug
-    report by John Smith)
-
-Version 1.6.31 [July 27, 2017]
-  No changes.
-
-Version 1.6.32beta01 [July 31, 2017]
-  Avoid possible NULL dereference in png_handle_eXIf when benign_errors
-    are allowed. Avoid leaking the input buffer "eXIf_buf".
-  Eliminated png_ptr->num_exif member from pngstruct.h and added num_exif
-    to arguments for png_get_eXIf() and png_set_eXIf().
-  Added calls to png_handle_eXIf(() in pngread.c and png_write_eXIf() in
-    pngwrite.c, and made various other fixes to png_write_eXIf().
-  Changed name of png_get_eXIF and png_set_eXIf() to png_get_eXIf_1() and
-    png_set_eXIf_1(), respectively, to avoid breaking API compatibility
-    with libpng-1.6.31.
-
-Version 1.6.32beta02 [August 1, 2017]
-  Updated contrib/libtests/pngunknown.c with eXIf chunk.
-
-Version 1.6.32beta03 [August 2, 2017]
-  Initialized btoa[] in pngstest.c
-  Stop memory leak when returning from png_handle_eXIf() with an error
-    (Bug report from the OSS-fuzz project).
-
-Version 1.6.32beta04 [August 2, 2017]
-  Replaced local eXIf_buf with info_ptr-eXIf_buf in png_handle_eXIf().
-  Update libpng.3 and libpng-manual.txt about eXIf functions.
-
-Version 1.6.32beta05 [August 2, 2017]
-  Restored png_get_eXIf() and png_set_eXIf() to maintain API compatability.
-
-Version 1.6.32beta06 [August 2, 2017]
-  Removed png_get_eXIf_1() and png_set_eXIf_1().
-
-Version 1.6.32beta07 [August 3, 2017]
-  Check length of all chunks except IDAT against user limit to fix an
-    OSS-fuzz issue (Fixes CVE-2017-12652).
-
-Version 1.6.32beta08 [August 3, 2017]
-  Check length of IDAT against maximum possible IDAT size, accounting
-    for height, rowbytes, interlacing and zlib/deflate overhead.
-  Restored png_get_eXIf_1() and png_set_eXIf_1(), because strlen(eXIf_buf)
-    does not work (the eXIf chunk data can contain zeroes).
-
-Version 1.6.32beta09 [August 3, 2017]
-  Require cmake-2.8.8 in CMakeLists.txt. Revised symlink creation,
-    no longer using deprecated cmake LOCATION feature (Clifford Yapp).
-  Fixed five-byte error in the calculation of IDAT maximum possible size.
-  
-Version 1.6.32beta10 [August 5, 2017]
-  Moved chunk-length check into a png_check_chunk_length() private
-    function (Suggested by Max Stepin).
-  Moved bad pngs from tests to contrib/libtests/crashers
-  Moved testing of bad pngs into a separate tests/pngtest-badpngs script
-  Added the --xfail (expected FAIL) option to pngtest.c. It writes XFAIL
-    in the output but PASS for the libpng test.
-  Require cmake-3.0.2 in CMakeLists.txt (Clifford Yapp).
-  Fix "const" declaration info_ptr argument to png_get_eXIf_1() and the
-    num_exif argument to png_get_eXIf_1() (Github Issue 171).
-
-Version 1.6.32beta11 [August 7, 2017]
-  Added "eXIf" to "chunks_to_ignore[]" in png_set_keep_unknown_chunks().
-  Added huge_IDAT.png and empty_ancillary_chunks.png to testpngs/crashers.
-  Make pngtest --strict, --relax, --xfail options imply -m (multiple).
-  Removed unused chunk_name parameter from png_check_chunk_length().
-  Relocated setting free_me for eXIf data, to stop an OSS-fuzz leak.
-  Initialize profile_header[] in png_handle_iCCP() to fix OSS-fuzz issue.
-  Initialize png_ptr->row_buf[0] to 255 in png_read_row() to fix OSS-fuzz UMR.
-  Attempt to fix a UMR in png_set_text_2() to fix OSS-fuzz issue.
-  Increase minimum zlib stream from 9 to 14 in png_handle_iCCP(), to account
-    for the minimum 'deflate' stream, and relocate the test to a point
-    after the keyword has been read.
-  Check that the eXIf chunk has at least 2 bytes and begins with "II" or "MM".
-
-Version 1.6.32rc01 [August 18, 2017]
-  Added a set of "huge_xxxx_chunk.png" files to contrib/testpngs/crashers,
-    one for each known chunk type, with length = 2GB-1.
-  Check for 0 return from png_get_rowbytes() and added some (size_t) typecasts
-    in contrib/pngminus/*.c to stop some Coverity issues (162705, 162706,
-    and 162707).
-  Renamed chunks in contrib/testpngs/crashers to avoid having files whose
-    names differ only in case; this causes problems with some platforms
-    (github issue #172).
-
-Version 1.6.32rc02 [August 22, 2017]
-  Added contrib/oss-fuzz directory which contains files used by the oss-fuzz
-    project (https://github.com/google/oss-fuzz/tree/master/projects/libpng).
-
-Version 1.6.32 [August 24, 2017]
-  No changes.
-
-Version 1.6.33beta01 [August 28, 2017]
-  Added PNGMINUS_UNUSED macro to contrib/pngminus/p*.c and added missing
-    parenthesis in contrib/pngminus/pnm2png.c (bug report by Christian Hesse).
-  Fixed off-by-one error in png_do_check_palette_indexes() (Bug report
-    by Mick P., Source Forge Issue #269).
-
-Version 1.6.33beta02 [September 3, 2017]
-  Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
-    to fix shortlived oss-fuzz issue 3234.
-  Compute a larger limit on IDAT because some applications write a deflate
-    buffer for each row (Bug report by Andrew Church).
-  Use current date (DATE) instead of release-date (RDATE) in last
-    changed date of contrib/oss-fuzz files.
-  Enabled ARM support in CMakeLists.txt (Bernd Kuhls).
-
-Version 1.6.33beta03 [September 14, 2017]
-  Fixed incorrect typecast of some arguments to png_malloc() and
-    png_calloc() that were png_uint_32 instead of png_alloc_size_t
-    (Bug report by "irwir" in Github libpng issue #175).
-  Use pnglibconf.h.prebuilt when building for ANDROID with cmake (Github
-    issue 162, by rcdailey).
-
-Version 1.6.33rc01 [September 20, 2017]
-  Initialize memory allocated by png_inflate to zero, using memset, to
-    stop an oss-fuzz "use of uninitialized value" detection in png_set_text_2()
-    due to truncated iTXt or zTXt chunk.
-  Initialize memory allocated by png_read_buffer to zero, using memset, to
-    stop an oss-fuzz "use of uninitialized value" detection in
-    png_icc_check_tag_table() due to truncated iCCP chunk.
-  Removed a redundant test (suggested by "irwir" in Github issue #180).
-
-Version 1.6.33rc02 [September 23, 2017]
-  Added an interlaced version of each file in contrib/pngsuite.
-  Relocate new memset() call in pngrutil.c.
-  Removed more redundant tests (suggested by "irwir" in Github issue #180).
-  Add support for loading images with associated alpha in the Simplified
-    API (Samuel Williams).
-
-Version 1.6.33 [September 28, 2017]
-  Revert contrib/oss-fuzz/libpng_read_fuzzer.cc to libpng-1.6.32 state.
-  Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
-  Add end_info structure and png_read_end() to the libpng fuzzer.
-
-Version 1.6.34 [September 29, 2017]
-  Removed contrib/pngsuite/i*.png; some of these were incorrect and caused
-    test failures.
-
 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
@@ -1,57 +1,28 @@
 # CMakeLists.txt

-# Copyright (C) 2007,2009-2017 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
-# Revised by Andreas Franek, 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 3.0.2)
-cmake_policy(VERSION 3.0.2)
-
-# 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")

-project(libpng ASM C)
+project(libpng C)
 enable_testing()

 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 34)
+set(PNGLIB_RELEASE 21)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})

-include(GNUInstallDirs)
-
 # needed packages
-
-#Allow users to specify location of Zlib,
-# Useful if zlib is being built alongside this as a sub-project
-option(PNG_BUILD_ZLIB "Custom zlib Location, else find_package is used" OFF)
-
-IF(NOT PNG_BUILD_ZLIB)
-  find_package(ZLIB REQUIRED)
-  include_directories(${ZLIB_INCLUDE_DIR})
-ENDIF(NOT PNG_BUILD_ZLIB)
+find_package(ZLIB REQUIRED)
+include_directories(${ZLIB_INCLUDE_DIR})

 if(NOT WIN32)
  find_library(M_LIBRARY
@@ -76,391 +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)

-option(PNG_HARDWARE_OPTIMIZATIONS "Enable Hardware Optimizations" ON)
-
-
-set(PNG_PREFIX "" CACHE STRING "Prefix to add to the API function names")
-set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
-
-if(PNG_HARDWARE_OPTIMIZATIONS)
-# set definitions and sources for arm
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
-  CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
-  set(PNG_ARM_NEON_POSSIBLE_VALUES check on off)
-  set(PNG_ARM_NEON "check" CACHE STRING "Enable ARM NEON optimizations:
-     check: (default) use internal checking code;
-     off: disable the optimizations;
-     on: turn on unconditionally.")
-  set_property(CACHE PNG_ARM_NEON PROPERTY STRINGS
-     ${PNG_ARM_NEON_POSSIBLE_VALUES})
-  list(FIND PNG_ARM_NEON_POSSIBLE_VALUES ${PNG_ARM_NEON} index)
-  if(index EQUAL -1)
-    message(FATAL_ERROR
-      " PNG_ARM_NEON must be one of [${PNG_ARM_NEON_POSSIBLE_VALUES}]")
-  elseif(NOT ${PNG_ARM_NEON} STREQUAL "no")
-    set(libpng_arm_sources
-      arm/arm_init.c
-      arm/filter_neon.S
-      arm/filter_neon_intrinsics.c)
-
-    if(${PNG_ARM_NEON} STREQUAL "on")
-      add_definitions(-DPNG_ARM_NEON_OPT=2)
-    elseif(${PNG_ARM_NEON} STREQUAL "check")
-      add_definitions(-DPNG_ARM_NEON_CHECK_SUPPORTED)
-    endif()
-  else()
-    add_definitions(-DPNG_ARM_NEON_OPT=0)
-  endif()
-endif()
-
-# set definitions and sources for powerpc
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "^powerpc*" OR
-	CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc64*" )
-  set(PNG_POWERPC_VSX_POSSIBLE_VALUES on off)
-  set(PNG_POWERPC_VSX "on" CACHE STRING "Enable POWERPC VSX optimizations:
-     off: disable the optimizations.")
-  set_property(CACHE PNG_POWERPC_VSX PROPERTY STRINGS
-     ${PNG_POWERPC_VSX_POSSIBLE_VALUES})
-  list(FIND PNG_POWERPC_VSX_POSSIBLE_VALUES ${PNG_POWERPC_VSX} index)
-  if(index EQUAL -1)
-    message(FATAL_ERROR
-      " PNG_POWERPC_VSX must be one of [${PNG_POWERPC_VSX_POSSIBLE_VALUES}]")
-  elseif(NOT ${PNG_POWERPC_VSX} STREQUAL "no")
-    set(libpng_powerpc_sources
-      powerpc/powerpc_init.c
-      powerpc/filter_vsx_intrinsics.c)
-    if(${PNG_POWERPC_VSX} STREQUAL "on")
-      add_definitions(-DPNG_POWERPC_VSX_OPT=2)
-    endif()
-  else()
-    add_definitions(-DPNG_POWERPC_VSX_OPT=0)
-  endif()
-endif()
-
-# set definitions and sources for intel
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?86" OR
-	CMAKE_SYSTEM_PROCESSOR MATCHES "^x86_64*" )
-  set(PNG_INTEL_SSE_POSSIBLE_VALUES on off)
-  set(PNG_INTEL_SSE "on" CACHE STRING "Enable INTEL_SSE optimizations:
-     off: disable the optimizations")
-  set_property(CACHE PNG_INTEL_SSE PROPERTY STRINGS
-     ${PNG_INTEL_SSE_POSSIBLE_VALUES})
-  list(FIND PNG_INTEL_SSE_POSSIBLE_VALUES ${PNG_INTEL_SSE} index)
-  if(index EQUAL -1)
-    message(FATAL_ERROR
-      " PNG_INTEL_SSE must be one of [${PNG_INTEL_SSE_POSSIBLE_VALUES}]")
-  elseif(NOT ${PNG_INTEL_SSE} STREQUAL "no")
-    set(libpng_intel_sources
-      intel/intel_init.c
-      intel/filter_sse2_intrinsics.c)
-    if(${PNG_INTEL_SSE} STREQUAL "on")
-      add_definitions(-DPNG_INTEL_SSE_OPT=1)
-    endif()
-  else()
-    add_definitions(-DPNG_INTEL_SSE_OPT=0)
-  endif()
-endif()
-
-# set definitions and sources for MIPS
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "mipsel*" OR
-	CMAKE_SYSTEM_PROCESSOR MATCHES "mips64el*" )
-  set(PNG_MIPS_MSA_POSSIBLE_VALUES on off)
-  set(PNG_MIPS_MSA "on" CACHE STRING "Enable MIPS_MSA optimizations:
-     off: disable the optimizations")
-  set_property(CACHE PNG_MIPS_MSA PROPERTY STRINGS
-     ${PNG_MIPS_MSA_POSSIBLE_VALUES})
-  list(FIND PNG_MIPS_MSA_POSSIBLE_VALUES ${PNG_MIPS_MSA} index)
-  if(index EQUAL -1)
-    message(FATAL_ERROR
-      " PNG_MIPS_MSA must be one of [${PNG_MIPS_MSA_POSSIBLE_VALUES}]")
-  elseif(NOT ${PNG_MIPS_MSA} STREQUAL "no")
-    set(libpng_mips_sources
-      mips/mips_init.c
-      mips/filter_msa_intrinsics.c)
-    if(${PNG_MIPS_MSA} STREQUAL "on")
-      add_definitions(-DPNG_MIPS_MSA_OPT=2)
-    endif()
-  else()
-    add_definitions(-DPNG_MIPS_MSA_OPT=0)
-  endif()
-endif()
-endif(PNG_HARDWARE_OPTIMIZATIONS)
-
 # 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 OR ANDROID)
-  # 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"
-    "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out")
-endif(NOT AWK OR ANDROID)
-
 # OUR SOURCES
 set(libpng_public_hdrs
  png.h
  pngconf.h
-  "${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h"
+  ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h
 )
-set(libpng_private_hdrs
-  pngpriv.h
-  pngdebug.h
-  pnginfo.h
-  pngstruct.h
-)
-if(AWK AND NOT ANDROID)
-  list(APPEND libpng_private_hdrs "${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
@@ -476,10 +88,6 @@ set(libpng_sources
  pngwrite.c
  pngwtran.c
  pngwutil.c
-  ${libpng_arm_sources}
-  ${libpng_intel_sources}
-  ${libpng_mips_sources}
-  ${libpng_powerpc_sources}
 )
 set(pngtest_sources
  pngtest.c
@@ -490,18 +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)
@@ -517,59 +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}
@@ -578,7 +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)
@@ -589,233 +160,79 @@ 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})
+  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()

-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)
-endif()
+# Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
+IF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+  SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY "lib")
+ENDIF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)

 # Set a variable with CMake code which:
 # Creates a symlink from src to dest (if possible) or alternatively
 # copies if different.
-include(CMakeParseArguments)
-
-function(CREATE_SYMLINK DEST_FILE)
-
-  cmake_parse_arguments(S "" "FILE;TARGET" "" ${ARGN})
-
-  if(NOT S_TARGET AND NOT S_FILE)
-    message(FATAL_ERROR "Specify either a TARGET or a FILE for CREATE_SYMLINK to link to.")
-  endif(NOT S_TARGET AND NOT S_FILE)
-
-  if(S_TARGET AND S_FILE)
-    message(FATAL_ERROR "CREATE_SYMLINK called with both source file ${S_FILE} and build target ${S_TARGET} arguments - can only handle 1 type per call.")
-  endif(S_TARGET AND S_FILE)
-
-  if(S_FILE)
-    # If we don't need to symlink something that's coming from a build target,
-    # we can go ahead and symlink/copy at configure time.
-
-    if(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-      execute_process(
-	COMMAND "${CMAKE_COMMAND}" -E copy_if_different ${S_FILE} ${DEST_FILE}
-	WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
-	)
-    else(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-      execute_process(
-	COMMAND ${CMAKE_COMMAND} -E create_symlink ${S_FILE} ${DEST_FILE}
-	WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
-	)
-    endif(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-  endif(S_FILE)
-
-  if(S_TARGET)
-    # We need to use generator expressions, which can be a bit tricky, so for
-    # simplicity make the symlink a POST_BUILD step and use the TARGET
-    # signature of add_custom_command.
-
-    if(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-      add_custom_command(TARGET ${S_TARGET} POST_BUILD
-	COMMAND "${CMAKE_COMMAND}" -E copy_if_different $<TARGET_LINKER_FILE_NAME:${S_TARGET}> $<TARGET_LINKER_FILE_DIR:${S_TARGET}>/${DEST_FILE}
-	)
-    else(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-      add_custom_command(TARGET ${S_TARGET} POST_BUILD
-	COMMAND "${CMAKE_COMMAND}" -E create_symlink $<TARGET_LINKER_FILE_NAME:${S_TARGET}> $<TARGET_LINKER_FILE_DIR:${S_TARGET}>/${DEST_FILE}
-	)
-    endif(CMAKE_HOST_WIN32 AND NOT CYGWIN AND NOT MSYS)
-
-  endif(S_TARGET)
-
-endfunction()
-
-# Create source generation scripts.
-configure_file(${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)
-
+macro(CREATE_SYMLINK SRC_FILE DEST_FILE)
+  FILE(REMOVE ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+  if(WIN32 AND NOT CYGWIN AND NOT MSYS)
+    ADD_CUSTOM_COMMAND(
+        OUTPUT ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE}   ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different  "${SRC_FILE}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE}
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different  "${SRC_FILE}" ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+        DEPENDS ${PNG_LIB_TARGETS}
+        )
+    ADD_CUSTOM_TARGET(${DEST_FILE}_COPY ALL DEPENDS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+  else(WIN32 AND NOT CYGWIN AND NOT MSYS)
+    get_filename_component(LINK_TARGET "${SRC_FILE}" NAME)
+    execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
+    execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+    execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+  endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
+endmacro()

 # libpng is a library so default to 'lib'
 if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
@@ -834,21 +251,31 @@ if(NOT WIN32 OR CYGWIN OR MINGW)
  set(LIBS        "-lz -lm")
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng.pc.in
    ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc @ONLY)
-  CREATE_SYMLINK(libpng.pc FILE ${PNGLIB_NAME}.pc)
+  CREATE_SYMLINK(${PNGLIB_NAME}.pc libpng.pc)

  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng-config.in
    ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config @ONLY)
-  CREATE_SYMLINK(libpng-config FILE ${PNGLIB_NAME}-config)
+  CREATE_SYMLINK(${PNGLIB_NAME}-config libpng-config)
 endif(NOT WIN32 OR CYGWIN OR MINGW)

 # SET UP LINKS
 if(PNG_SHARED)
-  set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.34
+  set_target_properties(${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.
@@ -871,20 +298,26 @@ 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)
-      CREATE_SYMLINK(libpng${CMAKE_IMPORT_LIBRARY_SUFFIX} TARGET png)
-      install(FILES $<TARGET_LINKER_FILE_DIR:png>/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX} DESTINATION ${CMAKE_INSTALL_LIBDIR})
+       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)
-      CREATE_SYMLINK(libpng${CMAKE_SHARED_LIBRARY_SUFFIX} TARGET png)
-      install(FILES $<TARGET_LINKER_FILE_DIR:png>/libpng${CMAKE_SHARED_LIBRARY_SUFFIX} DESTINATION ${CMAKE_INSTALL_LIBDIR})
+      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})
    endif(NOT WIN32)
  endif(PNG_SHARED)

  if(PNG_STATIC)
    if(NOT WIN32 OR CYGWIN OR MINGW)
-      CREATE_SYMLINK( libpng${CMAKE_STATIC_LIBRARY_SUFFIX} TARGET png_static)
-      install(FILES $<TARGET_LINKER_FILE_DIR:png_static>/libpng${CMAKE_STATIC_LIBRARY_SUFFIX} DESTINATION ${CMAKE_INSTALL_LIBDIR})
+      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})
    endif(NOT WIN32 OR CYGWIN OR MINGW)
 endif()
 endif()
@@ -901,11 +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)
@@ -914,7 +342,7 @@ if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
  install(FILES libpng.3 libpngpf.3      DESTINATION ${PNG_MAN_DIR}/man3)
  install(FILES png.5                    DESTINATION ${PNG_MAN_DIR}/man5)
  # Install pkg-config files
-  if(NOT CMAKE_HOST_WIN32 OR CYGWIN OR MINGW)
+  if(NOT WIN32 OR CYGWIN OR MINGW)
    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng.pc
            DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config
@@ -923,7 +351,7 @@ if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
            DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
            DESTINATION bin)
-  endif(NOT CMAKE_HOST_WIN32 OR CYGWIN OR MINGW)
+  endif(NOT WIN32 OR CYGWIN OR MINGW)
 endif()

 # On versions of CMake that support it, create an export file CMake
@@ -943,3 +371,4 @@ endif()
 # to create msvc import lib for mingw compiled shared lib
 # pexports libpng.dll > libpng.def
 # lib /def:libpng.def /machine:x86
+
--- a/178
+++ b/178
@@ -1,26 +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. Enabling or disabling hardware optimizations
-      XV. Changes to the build and configuration of libpng in libpng-1.5.x
-     XVI. Setjmp/longjmp issues
-    XVII. Common linking failures
-   XVIII. 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

@@ -49,9 +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
@@ -79,8 +75,8 @@ 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 https://zlib.net/.  You can
-place zlib in the same directory as libpng or in another directory.
+wherever you got libpng; otherwise go to http://zlib.net.  You can place
+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
@@ -91,24 +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",
@@ -122,8 +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
@@ -166,15 +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.
@@ -250,7 +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.

@@ -282,57 +271,7 @@ library to fail if they call functions not available in your library.
 The size of the library itself should not be an issue, because only
 those sections that are actually used will be loaded into memory.

-XIV. Enabling or disabling hardware optimizations
-
-Certain hardware capabilites, such as the Intel SSE instructions,
-are normally detected at run time. Enable them with configure options
-such as one of
-
-   --enable-arm-neon=yes
-   --enable-mips-msa=yes
-   --enable-intel-sse=yes
-   --enable-powerpc-vsx=yes
-
-or enable them all at once with
-
-   --enable-hardware-optimizations=yes
-
-or, if you are not using "configure", you can use one
-or more of
-
-   CPPFLAGS += "-DPNG_ARM_NEON"
-   CPPFLAGS += "-DPNG_MIPS_MSA"
-   CPPFLAGS += "-DPNG_INTEL_SSE"
-   CPPFLAGS += "-DPNG_POWERPC_VSX"
-
-See for example scripts/makefile.linux-opt
-
-If you wish to avoid using them,
-you can disable them via the configure option
-
-   --disable-hardware-optimizations
-
-to disable them all, or
-
-   --enable-intel-sse=no
-
-to disable a particular one,
-or via compiler-command options such as
-
-   CPPFLAGS += "-DPNG_ARM_NEON_OPT=0, -DPNG_MIPS_MSA_OPT=0,
-   -DPNG_INTEL_SSE_OPT=0, -DPNG_POWERPC_VSX_OPT=0"
-
-If you are using cmake, hardware optimizations are "on"
-by default. To disable them, use
-
-    cmake . -DPNG_ARM_NEON=no -DPNG_INTEL_SSE=no \
-            -DPNG_MIPS_MSA=no -DPNG_POWERPC_VSX=no
-
-or disable them all at once with
-
-    cmake . -DPNG_HARDWARE_OPTIMIZATIONS=no
-
-XV. Changes to the build and configuration of libpng in libpng-1.5.x
+XIV. Changes to the build and configuration of libpng in libpng-1.5.x

 Details of internal changes to the library code can be found in the CHANGES
 file and in the GIT repository logs.  These will be of no concern to the vast
@@ -368,7 +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
@@ -423,7 +362,7 @@ $PREFIX/include directory).  Do not edit pnglibconf.h after you have built
 libpng, because than the settings would not accurately reflect the settings
 that were used to build libpng.

-XVI. Setjmp/longjmp issues
+XV. Setjmp/longjmp issues

 Libpng uses setjmp()/longjmp() for error handling.  Unfortunately setjmp()
 is known to be not thread-safe on some platforms and we don't know of
@@ -432,7 +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.

@@ -441,25 +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.

-XVII. 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.
-
-XVIII. 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/37
+++ b/37
@@ -10,8 +10,8 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
-Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, 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
 added to the list of Contributing Authors:
@@ -22,9 +22,6 @@ added to the list of Contributing Authors:
   Cosmin Truta
   Gilles Vollant
   James Yu
-   Mandar Sahastrabuddhe
-   Google Inc.
-   Vadim Barkov

 and with the following additions to the disclaimer:

@@ -35,10 +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
@@ -62,9 +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.

@@ -105,29 +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 29, 2017
+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
@@ -45,22 +37,15 @@ 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 =\
   tests/pngtest\
-   tests/pngtest-badpngs\
   tests/pngvalid-gamma-16-to-8 tests/pngvalid-gamma-alpha-mode\
   tests/pngvalid-gamma-background tests/pngvalid-gamma-expand16-alpha-mode\
   tests/pngvalid-gamma-expand16-background\
@@ -98,21 +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
-
-if PNG_INTEL_SSE
-libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += intel/intel_init.c\
-	intel/filter_sse2_intrinsics.c
-endif
-
-if PNG_POWERPC_VSX
-libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += powerpc/powerpc_init.c\
-        powerpc/filter_vsx_intrinsics.c
-endif
-
 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h

 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
@@ -249,7 +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/19
+++ b/19
@@ -1,4 +1,4 @@
-README for libpng version 1.6.34 - September 29, 2017 (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.
@@ -23,7 +23,7 @@ earlier versions if you are using a shared library.  The type of the
 png_uint_32, which will affect shared-library applications that use
 this function.

-To avoid problems with changes to the internals of the png info_struct,
+To avoid problems with changes to the internals of png info_struct,
 new APIs have been made available in 0.95 to avoid direct application
 access to info_ptr.  These functions are the png_set_<chunk> and
 png_get_<chunk> functions.  These functions should be used when
@@ -88,11 +88,11 @@ zlib should be available at the same place that libpng is, or at zlib.net.

 You may also want a copy of the PNG specification.  It is available
 as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
-these at http://www.libpng.org/pub/png/pngdocs.html .
+these at http://www.libpng.org/pub/png/documents/

-This code is currently being archived at libpng.sourceforge.io in the
-[DOWNLOAD] area, and at http://libpng.download/src .  If you
-can't find it in any of those places, e-mail me, and I'll help you find it.
+This code is currently being archived at libpng.sf.net in the
+[DOWNLOAD] area, and at ftp://ftp.simplesystems.org.  If you can't find it
+in any of those places, e-mail me, and I'll help you find it.

 I am not a lawyer, but I believe that the Export Control Classification
 Number (ECCN) for libpng is EAR99, which means not subject to export
@@ -179,25 +179,18 @@ Files in this distribution:
      pngwtran.c    =>  Write data transformations
      pngwutil.c    =>  Write utility functions
      arm           =>  Contains optimized code for the ARM platform
-      powerpc       =>  Contains optimized code for the PowerPC platform
      contrib       =>  Contributions
-       arm-neon         =>  Optimized code for ARM-NEON platform
-       powerpc-vsx      =>  Optimized code for POWERPC-VSX platform
       examples         =>  Example programs
       gregbook         =>  source code for PNG reading and writing, from
                            Greg Roelofs' "PNG: The Definitive Guide",
                            O'Reilly, 1999
       libtests         =>  Test programs
-       mips-msa         =>  Optimized code for MIPS-MSA platform
       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
-      intel             =>  Optimized code for INTEL-SSE2 platform
-      mips              =>  Optimized code for MIPS platform
      projects      =>  Contains project files and workspaces for
                        building a DLL
       owatcom          =>  Contains a WATCOM project for building libpng
--- a/7
+++ b/7
@@ -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
@@ -24,7 +23,7 @@ Use greater precision when changing to linear gamma for compositing against
  background and doing rgb-to-gray transformation.
 Investigate pre-incremented loop counters and other loop constructions.
 Add interpolated method of handling interlacing.
+Switch to the simpler zlib (zlib/libpng) license if legally possible.
 Extend pngvalid.c to validate more of the libpng transformations.
-Refactor preprocessor conditionals to compile entire statements

 */
--- 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.S
+++ b/arm/filter_neon.S
@@ -1,9 +1,9 @@

 /* filter_neon.S - NEON optimised filter functions
 *
- * Copyright (c) 2014,2017 Glenn Randers-Pehrson
+ * Copyright (c) 2014 Glenn Randers-Pehrson
 * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * 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
@@ -16,7 +16,7 @@
 #define PNG_VERSION_INFO_ONLY
 #include "../pngpriv.h"

-#if (defined(__linux__) || defined(__FreeBSD__)) && defined(__ELF__)
+#if defined(__linux__) && defined(__ELF__)
 .section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
 #endif

--- 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],[1.6.34],[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=1.6.34
+PNGLIB_VERSION=1.6.21
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=34
+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 "$ac_cv_func_clock_gettime" = "yes"])
-
 AC_ARG_WITH(zlib-prefix,
   AS_HELP_STRING([[[--with-zlib-prefix]]],
      [prefix that may have been used in installed zlib]),
@@ -300,55 +268,6 @@ AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
 # HOST SPECIFIC OPTIONS
 # =====================
 #
-# DEFAULT
-# =======
-#
-AC_ARG_ENABLE([hardware-optimizations],
-   AS_HELP_STRING([[[--enable-hardware-optimizations]]],
-      [Enable hardware optimizations: =no/off, yes/on:]),
-   [case "$enableval" in
-      no|off)
-         # disable hardware optimization on all systems:
-         enable_arm_neon=no
-         AC_DEFINE([PNG_ARM_NEON_OPT], [0],
-           [Disable ARM_NEON optimizations])
-         enable_mips_msa=no
-         AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
-           [Disable MIPS_MSA optimizations])
-         enable_powerpc_vsx=no
-         AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
-           [Disable POWERPC VSX optimizations])
-         enable_intel_sse=no
-         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
-           [Disable INTEL_SSE optimizations])
-         ;;
-      *)
-         # allow enabling hardware optimization on any system:
-         case "$host_cpu" in
-            arm*|aarch64*)
-              enable_arm_neon=yes
-              AC_DEFINE([PNG_ARM_NEON_OPT], [0],
-                [Enable ARM_NEON optimizations])
-              ;;
-            mipsel*|mips64el*)
-              enable_mips_msa=yes
-              AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
-                [Enable MIPS_MSA optimizations])
-              ;;
-            i?86|x86_64)
-              enable_intel_sse=yes
-              AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
-                [Enable Intel SSE optimizations])
-              ;;
-            powerpc*|ppc64*)
-              enable_powerpc_vsx=yes
-              AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
-                [Enable POWERPC VSX optimizations])
-              ;;
-         esac
-         ;;
-   esac])
-
 # ARM
 # ===
 #
@@ -395,134 +314,6 @@ AM_CONDITIONAL([PNG_ARM_NEON],
      *)    test "$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])
-
-# 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 "$enable_intel_sse" != '';;
-    esac])
-
-# PowerPC
-# ===
-#
-# PowerPC VSX (SIMD) support.
-
-AC_ARG_ENABLE([powerpc-vsx],
-AS_HELP_STRING([[[--enable-powerpc-vsx]]],
-      [Enable POWERPC VSX optimizations: =no/off, check, api, yes/on:]
-      [no/off: disable the optimizations; check: use internal checking code]
-      [api: disable by default, enable by a call to png_set_option]
-      [yes/on: turn on unconditionally.]
-      [If not specified: determined by the compiler.]),
-   [case "$enableval" in
-      no|off)
-         # disable the default enabling on __ppc64__ systems:
-         AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
-                   [Disable POWERPC VSX optimizations])
-         # Prevent inclusion of the platform specific files below:
-         enable_powerpc_vsx=no;;
-      check)
-         AC_DEFINE([PNG_POWERPC_VSX_CHECK_SUPPORTED], [],
-                   [Check for POWERPC VSX support at run-time])
-         AC_MSG_WARN([--enable-powerpc-vsx Please check contrib/powerpc/README file]
-            [for the list of supported OSes.]);;
-      api)
-         AC_DEFINE([PNG_POWERPC_VSX_API_SUPPORTED], [],
-                   [Turn on POWERPC VSX optimizations at run-time]);;
-      yes|on)
-         AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
-                   [Enable POWERPC VSX optimizations])
-         AC_MSG_WARN([--enable-powerpc-vsx: please specify 'check' or 'api', if]
-            [you want the optimizations unconditionally pass '-maltivec -mvsx']
-            [or '-mcpu=power8'to the compiler.]);;
-      *)
-         AC_MSG_ERROR([--enable-powerpc-vsx=${enable_powerpc_vsx}: invalid value])
-   esac])
-
-# Add PowerPC specific files to all builds where the host_cpu is powerpc('powerpc*') or
-# where POWERPC optimizations were explicitly requested (this allows a fallback if a
-# future host CPU does not match 'powerpc*')
-
-AM_CONDITIONAL([PNG_POWERPC_VSX],
-   [test "$enable_powerpc_vsx" != 'no' &&
-    case "$host_cpu" in
-      powerpc*|ppc64*) :;;
-    esac])
-
-
 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])

 # Config files, substituting as above
--- a/contrib/arm-neon/android-ndk.c
+++ b/contrib/arm-neon/android-ndk.c
@@ -17,7 +17,7 @@
 *
 * Documentation:
 *    http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html
- *    https://code.google.com/p/android/issues/detail?id=49065
+ *    http://code.google.com/p/android/issues/detail?id=49065
 *
 * NOTE: this requires that libpng is built against the Android NDK and linked
 * with an implementation of the Android ARM 'cpu-features' library.  The code
--- a/contrib/arm-neon/linux.c
+++ b/contrib/arm-neon/linux.c
@@ -1,8 +1,8 @@
 /* contrib/arm-neon/linux.c
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- * Copyright (c) 2014, 2017 Glenn Randers-Pehrson
- * Written by John Bowler, 2014, 2017.
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by John Bowler, 2014.
+ * 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
@@ -62,7 +62,7 @@ png_have_neon(png_structp png_ptr)

               counter=0;
               state = Feature;
-               /* FALLTHROUGH */
+               /* FALL THROUGH */

            case Feature:
               /* Match 'FEATURE', ASCII case insensitive. */
@@ -75,7 +75,7 @@ png_have_neon(png_structp png_ptr)

               /* did not match 'feature' */
               state = SkipLine;
-               /* FALLTHROUGH */
+               /* FALL THROUGH */

            case SkipLine:
            skipLine:
@@ -110,7 +110,7 @@ png_have_neon(png_structp png_ptr)

               state = Neon;
               counter = 0;
-               /* FALLTHROUGH */
+               /* FALL THROUGH */

            case Neon:
               /* Look for 'neon' tag */
@@ -122,7 +122,7 @@ png_have_neon(png_structp png_ptr)
               }

               state = SkipTag;
-               /* FALLTHROUGH */
+               /* FALL THROUGH */

            case SkipTag:
               /* Skip non-space characters */
--- 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/examples/README.txt
+++ b/contrib/examples/README.txt
@@ -21,4 +21,4 @@ ORIGINAL AUTHORS
    of the people below claim any rights with regard to the contents of this
    directory.

-    John Bowler <jbowler at acm.org>
+    John Bowler <jbowler@acm.org>
--- a/contrib/examples/pngtopng.c
+++ b/contrib/examples/pngtopng.c
@@ -1,12 +1,10 @@
 /*- pngtopng
 *
- * COPYRIGHT: Written by John Cunningham Bowler, 2011, 2017.
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
 * 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.
 *
- * Last changed in libpng 1.6.29 [March 16, 2017]
- *
 * Read a PNG and write it out in a fixed format, using the 'simplified API'
 * that was introduced in libpng-1.6.0.
 *
@@ -61,27 +59,26 @@ int main(int argc, const char **argv)
               else
                  fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
                      image.message);
+
+               free(buffer);
            }

            else
+            {
               fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
                   image.message);

-            free(buffer);
+               /* This is the only place where a 'free' is required; libpng does
+                * the cleanup on error and success, but in this case we couldn't
+                * complete the read because of running out of memory.
+                */
+               png_image_free(&image);
+            }
         }

         else
-         {
            fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
               (unsigned long)PNG_IMAGE_SIZE(image));
-
-            /* This is the only place where a 'free' is required; libpng does
-             * the cleanup on error and success, but in this case we couldn't
-             * complete the read because of running out of memory and so libpng
-             * has not got to the point where it can do cleanup.
-             */
-            png_image_free(&image);
-         }
      }

      else
--- a/contrib/gregbook/README
+++ b/contrib/gregbook/README
@@ -15,7 +15,7 @@ of PBMPLUS/NetPBM) and converts them to PNG.

 The source code for all three demo programs currently compiles under
 Unix, OpenVMS, and 32-bit Windows.  (Special thanks to Martin Zinser,
-zinser at decus.de, for making the necessary changes for OpenVMS and for
+zinser@decus.de, for making the necessary changes for OpenVMS and for
 providing an appropriate build script.)  Build instructions can be found
 below.

@@ -55,7 +55,7 @@ mation and links to the latest version of the source code, and Chapters
 13-15 of the book for detailed discussion of the three programs.

 Greg Roelofs
-https://pobox.com/~newt/greg_contact.html
+http://pobox.com/~newt/greg_contact.html
 16 March 2008


@@ -63,7 +63,7 @@ BUILD INSTRUCTIONS

 - Prerequisites (in order of compilation):

-      - zlib            https://zlib.net/
+      - zlib            http://zlib.net/
      - libpng          http://www.libpng.org/pub/png/libpng.html
      - pngbook         http://www.libpng.org/pub/png/book/sources.html

--- a/contrib/gregbook/readpng.c
+++ b/contrib/gregbook/readpng.c
@@ -4,7 +4,7 @@

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2007,2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -264,12 +264,6 @@ uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
    *pRowbytes = rowbytes = png_get_rowbytes(png_ptr, info_ptr);
    *pChannels = (int)png_get_channels(png_ptr, info_ptr);

-    /* Guard against integer overflow */
-    if (height > ((size_t)(-1))/rowbytes) {
-        fprintf(stderr, "readpng:  image_data buffer would be too large\n",
-        return NULL;
-    }
-
    if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
        png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
        return NULL;
--- a/contrib/gregbook/readpng2.c
+++ b/contrib/gregbook/readpng2.c
@@ -54,8 +54,7 @@
  ---------------------------------------------------------------------------

   Changelog:
-     2015-11-12 - Check return value of png_get_bKGD() (Glenn R-P)
-     2017-04-22 - Guard against integer overflow (Glenn R-P)
+     %RDATE% - Check return value of png_get_bKGD() (Glenn R-P)

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

--- a/contrib/gregbook/readppm.c
+++ b/contrib/gregbook/readppm.c
@@ -9,7 +9,7 @@

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2007,2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -154,18 +154,13 @@ uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
    *pRowbytes = rowbytes = channels*width;
    *pChannels = channels;

-    Trace((stderr, "readpng_get_image:  rowbytes = %ld, height = %ld\n", rowbytes, height));
-
-    /* Guard against integer overflow */
-    if (height > ((size_t)(-1))/rowbytes) {
-        fprintf(stderr, PROGNAME ":  image_data buffer would be too large\n",
-        return NULL;
-    }
-
    if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
        return NULL;
    }

+    Trace((stderr, "readpng_get_image:  rowbytes = %ld, height = %ld\n", rowbytes, height));
+
+
    /* now we can go ahead and just read the whole image */

    if (fread(image_data, 1L, rowbytes*height, saved_infile) <
--- a/contrib/gregbook/rpng-win.c
+++ b/contrib/gregbook/rpng-win.c
@@ -24,11 +24,10 @@
    - 1.10:  enabled "message window"/console (thanks to David Geldreich)
    - 2.00:  dual-licensed (added GNU GPL)
    - 2.01:  fixed improper display of usage screen on PNG error(s)
-    - 2.02:  check for integer overflow (Glenn R-P)

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2008, 2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2008 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -183,7 +182,7 @@ int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, PSTR cmd, int showmode)
 #ifndef __CYGWIN__
    /* First reenable console output, which normally goes to the bit bucket
     * for windowed apps.  Closing the console window will terminate the
-     * app.  Thanks to David.Geldreich at realviz.com for supplying the magical
+     * app.  Thanks to David.Geldreich@realviz.com for supplying the magical
     * incantation. */

    AllocConsole();
@@ -497,12 +496,6 @@ static int rpng_win_create_window(HINSTANCE hInst, int showmode)

    wimage_rowbytes = ((3*image_width + 3L) >> 2) << 2;

-    /* Guard against integer overflow */
-    if (image_height > ((size_t)(-1))/wimage_rowbytes) {
-        fprintf(stderr, PROGNAME ":  image_data buffer would be too large\n");
-        return 4;   /* fail */
-    }
-
    if (!(dib = (uch *)malloc(sizeof(BITMAPINFOHEADER) +
                              wimage_rowbytes*image_height)))
    {
--- a/contrib/gregbook/rpng-x.c
+++ b/contrib/gregbook/rpng-x.c
@@ -28,11 +28,10 @@
    - 2.01:  fixed improper display of usage screen on PNG error(s)
    - 2.02:  Added "void(argc);" statement to quiet pedantic compiler warnings
             about unused variable (GR-P)
-    - 2.03:  check for integer overflow (Glenn R-P)

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2008, 2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2008 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
--- a/contrib/gregbook/rpng2-win.c
+++ b/contrib/gregbook/rpng2-win.c
@@ -33,11 +33,12 @@
    - 2.02:  fixed improper display of usage screen on PNG error(s); fixed
              unexpected-EOF and file-read-error cases
    - 2.03:  removed runtime MMX-enabling/disabling and obsolete -mmx* options
-    - 2.04:  check for integer overflow (Glenn R-P)
+    - 2.04:
+             (GR-P)

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2008, 2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2008 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -300,7 +301,7 @@ int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, PSTR cmd, int showmode)
 #ifndef __CYGWIN__
    /* Next reenable console output, which normally goes to the bit bucket
     * for windowed apps.  Closing the console window will terminate the
-     * app.  Thanks to David.Geldreich at realviz.com for supplying the magical
+     * app.  Thanks to David.Geldreich@realviz.com for supplying the magical
     * incantation. */

    AllocConsole();
@@ -649,13 +650,6 @@ static void rpng2_win_init()
    Trace((stderr, "  width  = %ld\n", rpng2_info.width))
    Trace((stderr, "  height = %ld\n", rpng2_info.height))

-    /* Guard against integer overflow */
-    if (rpng2_info.height > ((size_t)(-1))/rowbytes) {
-        fprintf(stderr, PROGNAME ":  image_data buffer would be too large\n",
-        readpng2_cleanup(&rpng2_info);
-        return;
-    }
-
    rpng2_info.image_data = (uch *)malloc(rowbytes * rpng2_info.height);
    if (!rpng2_info.image_data) {
        readpng2_cleanup(&rpng2_info);
--- a/contrib/gregbook/rpng2-x.c
+++ b/contrib/gregbook/rpng2-x.c
@@ -44,11 +44,9 @@
    - 2.04:  Added "void(foo);" statements to quiet pedantic compiler warnings
             about unused variables (GR-P)
    - 2.05:  Use nanosleep() instead of usleep(), which is deprecated (GR-P).
-    - 2.06:  check for integer overflow (Glenn R-P)
  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2010, 2014-2015, 2017 Greg Roelofs.  All rights
-      reserved.
+      Copyright (c) 1998-2010, 2014-2015 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -782,13 +780,6 @@ static void rpng2_x_init(void)
    Trace((stderr, "  width  = %ld\n", rpng2_info.width))
    Trace((stderr, "  height = %ld\n", rpng2_info.height))

-    /* Guard against integer overflow */
-    if (rpng2_info.height > ((size_t)(-1))/rpng2_info.rowbytes) {
-        fprintf(stderr, PROGNAME ":  image_data buffer would be too large\n");
-        readpng2_cleanup(&rpng2_info);
-        return;
-    }
-
    rpng2_info.image_data = (uch *)malloc(rowbytes * rpng2_info.height);
    if (!rpng2_info.image_data) {
        readpng2_cleanup(&rpng2_info);
--- a/contrib/gregbook/wpng.c
+++ b/contrib/gregbook/wpng.c
@@ -29,7 +29,6 @@
    - 1.04:  fixed DOS/OS2/Win32 detection, including partial Cygwin fix
              (see http://home.att.net/~perlspinr/diffs/GregBook_cygwin.diff)
    - 2.00:  dual-licensed (added GNU GPL)
-    - 2.01:  check for integer overflow (Glenn R-P)

        [REPORTED BUG (win32 only):  "contrib/gregbook/wpng.c - cmd line
         dose not work!  In order to do something useful I needed to redirect
@@ -39,7 +38,7 @@

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2007, 2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
@@ -703,18 +702,7 @@ int main(int argc, char **argv)
    if (wpng_info.interlaced) {
        long i;
        ulg bytes;
-        ulg image_bytes;
-
-        /* Guard against integer overflow */
-        if (wpng_info_height > ((size_t)(-1)/rowbytes ||
-            wpng_info_height > ((ulg)(-1)/rowbytes) {
-            fprintf(stderr, PROGNAME ":  image_data buffer too large\n");
-            writepng_cleanup(&wpng_info);
-            wpng_cleanup();
-            exit(5);
-        }
-
-        image_bytes = rowbytes * wpng_info.height;
+        ulg image_bytes = rowbytes * wpng_info.height;   /* overflow? */

        wpng_info.image_data = (uch *)malloc(image_bytes);
        wpng_info.row_pointers = (uch **)malloc(wpng_info.height*sizeof(uch *));
--- a/contrib/gregbook/writepng.c
+++ b/contrib/gregbook/writepng.c
@@ -4,7 +4,7 @@

  ---------------------------------------------------------------------------

-      Copyright (c) 1998-2007, 2017 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.

      This software is provided "as is," without warranty of any kind,
      express or implied.  In no event shall the author or contributors
--- 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
@@ -1,8 +1,9 @@
 /*-
 * pngstest.c
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- * Copyright (c) 2013-2017 John Cunningham Bowler
+ * Copyright (c) 2013-2015 John Cunningham Bowler
+ *
+ * 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
@@ -34,15 +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"

@@ -107,18 +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);
 }

@@ -323,7 +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
@@ -332,19 +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)
@@ -357,12 +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 */
@@ -766,15 +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;
@@ -2610,9 +2578,9 @@ compare_two_images(Image *a, Image *b, int via_linear,
   const unsigned int b_sample = PNG_IMAGE_SAMPLE_SIZE(formatb);
   int alpha_added, alpha_removed;
   int bchannels;
+   int btoa[4];
   png_uint_32 y;
   Transform tr;
-   int btoa[4]={0,0,0,0};

   /* This should never happen: */
   if (width != b->image.width || height != b->image.height)
@@ -2745,27 +2713,22 @@ compare_two_images(Image *a, Image *b, int via_linear,
       */
      else if ((a->opts & ACCUMULATE) == 0)
      {
-#        ifdef __GNUC__
-#           define BYTE_CHARS 20 /* 2^32: GCC sprintf warning */
-#        else
-#           define BYTE_CHARS 3 /* 2^8: real maximum value */
-#        endif
         /* Check the original image first,
          * TODO: deal with input images with bad pixel values?
          */
         if (amax >= a->image.colormap_entries)
         {
-            char pindex[3+2*BYTE_CHARS];
-            sprintf(pindex, "%d[%u]", amax,
-               (png_byte)/*SAFE*/a->image.colormap_entries);
+            char pindex[9];
+            sprintf(pindex, "%d[%lu]", amax,
+               (unsigned long)a->image.colormap_entries);
            return logerror(a, a->file_name, ": bad pixel index: ", pindex);
         }

         else if (bmax >= b->image.colormap_entries)
         {
-            char pindex[3+2*BYTE_CHARS];
-            sprintf(pindex, "%d[%u]", bmax,
-               (png_byte)/*SAFE*/b->image.colormap_entries);
+            char pindex[9];
+            sprintf(pindex, "%d[%lu]", bmax,
+               (unsigned long)b->image.colormap_entries);
            return logerror(b, b->file_name, ": bad pixel index: ", pindex);
         }
      }
@@ -2885,13 +2848,10 @@ compare_two_images(Image *a, Image *b, int via_linear,
               {
                  case 4:
                     if (pua[btoa[3]] != pub[3]) break;
-                     /* FALLTHROUGH */
                  case 3:
                     if (pua[btoa[2]] != pub[2]) break;
-                     /* FALLTHROUGH */
                  case 2:
                     if (pua[btoa[1]] != pub[1]) break;
-                     /* FALLTHROUGH */
                  case 1:
                     if (pua[btoa[0]] != pub[0]) break;
                     if (alpha_added != 4 && pub[alpha_added] != 65535) break;
@@ -2907,13 +2867,10 @@ compare_two_images(Image *a, Image *b, int via_linear,
               {
                  case 4:
                     if (psa[btoa[3]] != psb[3]) break;
-                     /* FALLTHROUGH */
                  case 3:
                     if (psa[btoa[2]] != psb[2]) break;
-                     /* FALLTHROUGH */
                  case 2:
                     if (psa[btoa[1]] != psb[1]) break;
-                     /* FALLTHROUGH */
                  case 1:
                     if (psa[btoa[0]] != psb[0]) break;
                     if (alpha_added != 4 && psb[alpha_added] != 255) break;
@@ -3051,14 +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 */
@@ -3139,8 +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
@@ -3202,14 +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];

@@ -3229,51 +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
@@ -3449,8 +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);
@@ -3488,7 +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;
@@ -3497,17 +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)
   {
@@ -3522,17 +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;
@@ -3558,16 +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)
@@ -3824,6 +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 1.6.32 [August 24, 2017]
- * Copyright (c) 2015,2017 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
@@ -114,7 +103,6 @@ typedef png_byte *png_const_bytep;
 #define png_PLTE PNG_U32( 80,  76,  84,  69)
 #define png_bKGD PNG_U32( 98,  75,  71,  68)
 #define png_cHRM PNG_U32( 99,  72,  82,  77)
-#define png_eXIf PNG_U32(101,  88,  73, 102) /* registered July 2017 */
 #define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
 #define png_gAMA PNG_U32(103,  65,  77,  65)
 #define png_gIFg PNG_U32(103,  73,  70, 103)
@@ -211,13 +199,6 @@ static struct
         1,
 #     endif
      1,  START, 0 },
-   { "eXIf", PNG_INFO_eXIf, png_eXIf,
-#     ifdef PNG_READ_eXIf_SUPPORTED
-         0,
-#     else
-         1,
-#     endif
-      1,  END, 0 },
   { "gAMA", PNG_INFO_gAMA, png_gAMA,
 #     ifdef PNG_READ_gAMA_SUPPORTED
         0,
@@ -486,7 +467,7 @@ get_valid(display *d, png_infop info_ptr)
      png_textp text;
      png_uint_32 ntext = png_get_text(d->png_ptr, info_ptr, &text, NULL);

-      while (ntext > 0) switch (text[--ntext].compression)
+      while (ntext-- > 0) switch (text[ntext].compression)
      {
         case -1:
            flags |= PNG_INFO_tEXt;
@@ -622,7 +603,7 @@ get_unknown(display *d, png_infop info_ptr, int after_IDAT)
                  ++(d->error_count);
                  break;
               }
-               /* FALLTHROUGH */ /* (safe) */
+               /* FALL THROUGH (safe) */
            case PNG_HANDLE_CHUNK_ALWAYS:
               break;
         }
@@ -634,7 +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 */
@@ -653,8 +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*/,
@@ -1020,20 +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
@@ -1098,7 +1065,7 @@ static const char *standard_tests[] =
 "sTER", "sTER=if-safe", 0,
 "IDAT", "default=discard", "IDAT=save", 0,
 "sAPI", "bKGD=save", "cHRM=save", "gAMA=save", "all=discard", "iCCP=save",
-   "sBIT=save", "sRGB=save", "eXIf=save", 0,
+   "sBIT=save", "sRGB=save", 0,
 0/*end*/
 };

@@ -1278,7 +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 */

@@ -1289,6 +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
@@ -1,8 +1,9 @@

 /* pngvalid.c - validate libpng by constructing then reading png files.
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- * Copyright (c) 2014-2017 John Cunningham Bowler
+ * Last changed in libpng 1.6.21 [January 15, 2016]
+ * Copyright (c) 2014-2016 Glenn Randers-Pehrson
+ * Written by John Cunningham Bowler
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -61,10 +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.
@@ -130,17 +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.
 */
@@ -307,33 +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 */
@@ -343,7 +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 */

@@ -352,7 +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 */

@@ -708,8 +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 */
@@ -765,13 +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;
@@ -781,9 +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;

@@ -870,11 +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;
@@ -897,11 +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);
@@ -915,6 +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)
@@ -945,52 +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;
@@ -1241,7 +1204,7 @@ store_image_check(const png_store* ps, png_const_structp pp, int iImage)

      image += 2; /* skip image first row markers */

-      for (; rows > 0; --rows)
+      while (rows-- > 0)
      {
         if (image[-2] != 190 || image[-1] != 239)
            png_error(pp, "row start overwritten");
@@ -1256,119 +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
@@ -1388,6 +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)
@@ -1412,6 +1289,7 @@ store_read_buffer_avail(png_store *ps)

   return 0;
 }
+#endif

 static int
 store_read_buffer_next(png_store *ps)
@@ -1463,240 +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)
 {
@@ -1706,33 +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 */

@@ -2103,11 +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
@@ -2122,11 +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;
      }
@@ -2964,6 +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)
@@ -3003,7 +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;

@@ -3013,7 +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;

@@ -3054,7 +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;
@@ -3071,7 +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;
@@ -3137,8 +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. */
@@ -3679,10 +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
   }
 }

@@ -3705,8 +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;
@@ -3715,7 +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);
      }
@@ -3723,7 +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;
   }

@@ -4010,11 +3648,8 @@ check_interlace_type(int const interlace_type)
 #  define do_own_interlace 1
 #endif /* WRITE_INTERLACING tests */

-#if PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
-#   define CAN_WRITE_INTERLACE 1
-#else
-#   define CAN_WRITE_INTERLACE 0
-#endif
+#define CAN_WRITE_INTERLACE\
+   PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED

 /* Do the same thing for read interlacing; this controls whether read tests do
 * their own de-interlace or use libpng.
@@ -6584,16 +6219,16 @@ transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
   {
   case PNG_COLOR_TYPE_PALETTE:
      if (dp->output_bit_depth > 8) goto error;
-      /* FALLTHROUGH */
+      /*FALL THROUGH*/
   case PNG_COLOR_TYPE_GRAY:
      if (dp->output_bit_depth == 1 || dp->output_bit_depth == 2 ||
         dp->output_bit_depth == 4)
         break;
-      /* FALLTHROUGH */
+      /*FALL THROUGH*/
   default:
      if (dp->output_bit_depth == 8 || dp->output_bit_depth == 16)
         break;
-      /* FALLTHROUGH */
+      /*FALL THROUGH*/
   error:
      {
         char message[128];
@@ -7678,7 +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.;
@@ -7742,11 +7377,13 @@ image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
          * NOTE: this number only affects the internal limit check in pngvalid,
          * it has no effect on the limits applied to the libpng values.
          */
-#if DIGITIZE
-          that->pm->limit += pow( 2.0/255, data.gamma);
-#else
-          that->pm->limit += pow( 1.0/255, data.gamma);
-#endif
+         that->pm->limit += pow(
+#        if DIGITIZE
+            2.0
+#        else
+            1.0
+#        endif
+            /255, data.gamma);
      }
   }

@@ -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);
@@ -9994,9 +9631,9 @@ gamma_component_validate(const char *name, const validate_info *vi,
               case PNG_BACKGROUND_GAMMA_FILE:
               case PNG_BACKGROUND_GAMMA_UNIQUE:
                  use_background = (alpha >= 0 && alpha < 1);
+                  /*FALL THROUGH*/
 #           endif
 #           ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-               /* FALLTHROUGH */
               case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
               case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
               case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
@@ -11427,36 +11064,23 @@ perform_interlace_macro_validation(void)
       */
      for (v=0;;)
      {
-         /* The first two tests overflow if the pass row or column is outside
-          * the possible range for a 32-bit result.  In fact the values should
-          * never be outside the range for a 31-bit result, but checking for 32
-          * bits here ensures that if an app uses a bogus pass row or column
-          * (just so long as it fits in a 32 bit integer) it won't get a
-          * possibly dangerous overflow.
-          */
         /* First the base 0 stuff: */
-         if (v < png_pass_rows(0xFFFFFFFFU, pass))
+         m = PNG_ROW_FROM_PASS_ROW(v, pass);
+         f = png_row_from_pass_row(v, pass);
+         if (m != f)
         {
-            m = PNG_ROW_FROM_PASS_ROW(v, pass);
-            f = png_row_from_pass_row(v, pass);
-            if (m != f)
-            {
-               fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
-                  v, pass, m, f);
-               exit(99);
-            }
+            fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
+               v, pass, m, f);
+            exit(99);
         }

-         if (v < png_pass_cols(0xFFFFFFFFU, pass))
+         m = PNG_COL_FROM_PASS_COL(v, pass);
+         f = png_col_from_pass_col(v, pass);
+         if (m != f)
         {
-            m = PNG_COL_FROM_PASS_COL(v, pass);
-            f = png_col_from_pass_col(v, pass);
-            if (m != f)
-            {
-               fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
-                  v, pass, m, f);
-               exit(99);
-            }
+            fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
+               v, pass, m, f);
+            exit(99);
         }

         m = PNG_ROW_IN_INTERLACE_PASS(v, pass);
--- 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/oss-fuzz/Dockerfile
+++ b/contrib/oss-fuzz/Dockerfile
@@ -1,24 +0,0 @@
-# Copyright 2016 Google Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-################################################################################
-
-FROM gcr.io/oss-fuzz-base/base-builder
-MAINTAINER glennrp@gmail.com
-RUN apt-get update && apt-get install -y make autoconf automake libtool zlib1g-dev
-
-RUN git clone --depth 1 https://github.com/glennrp/libpng.git
-RUN (cd libpng; git log | head -1)
-WORKDIR libpng
-COPY build.sh $SRC/
--- a/contrib/oss-fuzz/README.txt
+++ b/contrib/oss-fuzz/README.txt
@@ -1,37 +0,0 @@
-Last changed in libpng 1.6.33 [September 28, 2017]
-Copyright (c) 2017 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
-
-Files in this directory are used by the oss-fuzz project
-(https://github.com/google/oss-fuzz/tree/master/projects/libpng).
-for "fuzzing" libpng.
-
-They were licensed by Google Inc, using the BSD-like Chromium license,
-which may be found at https://cs.chromium.org/chromium/src/LICENSE, or, if
-noted in the source, under the Apache-2.0 license, which may
-be found at http://www.apache.org/licenses/LICENSE-2.0 .
-If they have been modified, the derivatives are copyright Glenn Randers-Pehrson
-and are released under the same licenses as the originals.  Several of
-the original files (libpng_read_fuzzer.options, png.dict, project.yaml)
-had no licensing information; we assumed that these were under the Chromium
-license. Any new files are released under the libpng license (see png.h).
-
-The files are
-                            Original
- Filename                   or derived   Copyright          License
- =========================  ==========   ================   ==========
- Dockerfile*                derived      2017, Glenn R-P    Apache 2.0
- build.sh*                  derived      2017, Glenn R-P    Apache 2.0
- libpng_read_fuzzer.cc      derived      2017, Glenn R-P    Chromium
- libpng_read_fuzzer.options original     2015, Chrome Devs  Chromium
- png.dict                   original     2015, Chrome Devs  Chromium
- README.txt (this file)     original     2017, Glenn R-P    libpng
-
- * Dockerfile and build.sh are copies of the files used by oss-fuzz.
-   png.dict and libpng_read_fuzzer.* are the actual files used by oss-fuzz,
-   which retrieves them from the libpng repository at Github.
-
-To do: exercise the progressive reader and the png encoder.
--- a/contrib/oss-fuzz/build.sh
+++ b/contrib/oss-fuzz/build.sh
@@ -1,50 +0,0 @@
-#!/bin/bash -eu
-# Copyright 2017 Glenn Randers-Pehrson
-# Copyright 2016 Google Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-# Last changed in libpng 1.6.33 [September 28, 2017]
-#
-# Revisions by Glenn Randers-Pehson, 2017:
-# 1. Build only the library, not the tools (changed "make -j$(nproc) all" to
-#     "make -j$(nproc) libpng16.la").
-# 2. Disabled WARNING and WRITE options in pnglibconf.dfa.
-################################################################################
-
-# Disable logging via library build configuration control.
-cat scripts/pnglibconf.dfa | \
-  sed -e "s/option STDIO/option STDIO disabled/" \
-      -e "s/option WARNING /option WARNING disabled/" \
-      -e "s/option WRITE enables WRITE_INT_FUNCTIONS/option WRITE disabled/" \
-> scripts/pnglibconf.dfa.temp
-mv scripts/pnglibconf.dfa.temp scripts/pnglibconf.dfa
-
-# build the library.
-autoreconf -f -i
-./configure
-make -j$(nproc) clean
-make -j$(nproc) libpng16.la
-
-# build libpng_read_fuzzer.
-$CXX $CXXFLAGS -std=c++11 -I. \
-     $SRC/libpng/contrib/oss-fuzz/libpng_read_fuzzer.cc \
-     -o $OUT/libpng_read_fuzzer \
-     -lFuzzingEngine .libs/libpng16.a -lz
-
-# add seed corpus.
-find $SRC/libpng -name "*.png" | grep -v crashers | \
-     xargs zip $OUT/libpng_read_fuzzer_seed_corpus.zip
-
-cp $SRC/libpng/contrib/oss-fuzz/*.dict \
-     $SRC/libpng/contrib/oss-fuzz/*.options $OUT/
--- a/contrib/oss-fuzz/libpng_read_fuzzer.cc
+++ b/contrib/oss-fuzz/libpng_read_fuzzer.cc
@@ -1,180 +0,0 @@
-
-// libpng_read_fuzzer.cc
-// Copyright 2017 Glenn Randers-Pehrson
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that may
-// be found in the LICENSE file https://cs.chromium.org/chromium/src/LICENSE
-
-// Last changed in libpng 1.6.32 [August 24, 2017]
-
-// The modifications in 2017 by Glenn Randers-Pehrson include
-// 1. addition of a PNG_CLEANUP macro,
-// 2. setting the option to ignore ADLER32 checksums,
-// 3. adding "#include <string.h>" which is needed on some platforms
-//    to provide memcpy().
-// 4. adding read_end_info() and creating an end_info structure.
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-#include <vector>
-
-#define PNG_INTERNAL
-#include "png.h"
-
-#define PNG_CLEANUP \
-  if(png_handler.png_ptr) \
-  { \
-    if (png_handler.row_ptr) \
-      png_free(png_handler.png_ptr, png_handler.row_ptr); \
-    if (png_handler.end_info_ptr) \
-      png_destroy_read_struct(&png_handler.png_ptr, &png_handler.info_ptr,\
-        &png_handler.end_info_ptr); \
-    else if (png_handler.info_ptr) \
-      png_destroy_read_struct(&png_handler.png_ptr, &png_handler.info_ptr,\
-        nullptr); \
-    else \
-      png_destroy_read_struct(&png_handler.png_ptr, nullptr, nullptr); \
-    png_handler.png_ptr = nullptr; \
-    png_handler.row_ptr = nullptr; \
-    png_handler.info_ptr = nullptr; \
-    png_handler.end_info_ptr = nullptr; \
-  }
-
-struct BufState {
-  const uint8_t* data;
-  size_t bytes_left;
-};
-
-struct PngObjectHandler {
-  png_infop info_ptr = nullptr;
-  png_structp png_ptr = nullptr;
-  png_infop end_info_ptr = nullptr;
-  png_voidp row_ptr = nullptr;
-  BufState* buf_state = nullptr;
-
-  ~PngObjectHandler() {
-    if (row_ptr)
-      png_free(png_ptr, row_ptr);
-    if (end_info_ptr)
-      png_destroy_read_struct(&png_ptr, &info_ptr, &end_info_ptr);
-    else if (info_ptr) 
-      png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
-    else
-      png_destroy_read_struct(&png_ptr, nullptr, nullptr);
-    delete buf_state;
-  }
-};
-
-void user_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
-  BufState* buf_state = static_cast<BufState*>(png_get_io_ptr(png_ptr));
-  if (length > buf_state->bytes_left) {
-    png_error(png_ptr, "read error");
-  }
-  memcpy(data, buf_state->data, length);
-  buf_state->bytes_left -= length;
-  buf_state->data += length;
-}
-
-static const int kPngHeaderSize = 8;
-
-// Entry point for LibFuzzer.
-// Roughly follows the libpng book example:
-// http://www.libpng.org/pub/png/book/chapter13.html
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  if (size < kPngHeaderSize) {
-    return 0;
-  }
-
-  std::vector<unsigned char> v(data, data + size);
-  if (png_sig_cmp(v.data(), 0, kPngHeaderSize)) {
-    // not a PNG.
-    return 0;
-  }
-
-  PngObjectHandler png_handler;
-  png_handler.png_ptr = nullptr;
-  png_handler.row_ptr = nullptr;
-  png_handler.info_ptr = nullptr;
-  png_handler.end_info_ptr = nullptr;
-
-  png_handler.png_ptr = png_create_read_struct
-    (PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
-  if (!png_handler.png_ptr) {
-    return 0;
-  }
-
-  png_handler.info_ptr = png_create_info_struct(png_handler.png_ptr);
-  if (!png_handler.info_ptr) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  png_handler.end_info_ptr = png_create_info_struct(png_handler.png_ptr);
-  if (!png_handler.end_info_ptr) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  png_set_crc_action(png_handler.png_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
-#ifdef PNG_IGNORE_ADLER32
-  png_set_option(png_handler.png_ptr, PNG_IGNORE_ADLER32, PNG_OPTION_ON);
-#endif
-
-  // Setting up reading from buffer.
-  png_handler.buf_state = new BufState();
-  png_handler.buf_state->data = data + kPngHeaderSize;
-  png_handler.buf_state->bytes_left = size - kPngHeaderSize;
-  png_set_read_fn(png_handler.png_ptr, png_handler.buf_state, user_read_data);
-  png_set_sig_bytes(png_handler.png_ptr, kPngHeaderSize);
-
-  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  // Reading.
-  png_read_info(png_handler.png_ptr, png_handler.info_ptr);
-  png_handler.row_ptr = png_malloc(
-      png_handler.png_ptr, png_get_rowbytes(png_handler.png_ptr,
-                                               png_handler.info_ptr));
-
-  // reset error handler to put png_deleter into scope.
-  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  png_uint_32 width, height;
-  int bit_depth, color_type, interlace_type, compression_type;
-  int filter_type;
-
-  if (!png_get_IHDR(png_handler.png_ptr, png_handler.info_ptr, &width,
-                    &height, &bit_depth, &color_type, &interlace_type,
-                    &compression_type, &filter_type)) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  // This is going to be too slow.
-  if (width && height > 100000000 / width) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  int passes = png_set_interlace_handling(png_handler.png_ptr);
-  png_start_read_image(png_handler.png_ptr);
-
-  for (int pass = 0; pass < passes; ++pass) {
-    for (png_uint_32 y = 0; y < height; ++y) {
-      png_read_row(png_handler.png_ptr,
-                   static_cast<png_bytep>(png_handler.row_ptr), nullptr);
-    }
-  }
-
-  png_read_end(png_handler.png_ptr, png_handler.end_info_ptr);
-
-  PNG_CLEANUP
-  return 0;
-}
--- a/contrib/oss-fuzz/libpng_read_fuzzer.options
+++ b/contrib/oss-fuzz/libpng_read_fuzzer.options
@@ -1,2 +0,0 @@
-[libfuzzer]
-dict = png.dict
--- a/contrib/oss-fuzz/newcc
+++ b/contrib/oss-fuzz/newcc
@@ -1,190 +0,0 @@
-
-// libpng_read_fuzzer.cc
-// Copyright 2017 Glenn Randers-Pehrson
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that may
-// be found in the LICENSE file https://cs.chromium.org/chromium/src/LICENSE
-
-// Last changed in libpng 1.6.33beta03 [September 27, 2017]
-
-// The modifications in 2017 by Glenn Randers-Pehrson include
-// 1. addition of a PNG_CLEANUP macro,
-// 2. setting the option to ignore ADLER32 checksums,
-// 3. adding "#include <string.h>" which is needed on some platforms
-//    to provide memcpy().
-// 4. adding read_end_info() and creating an end_info structure.
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-#include <vector>
-
-#define PNG_INTERNAL
-#include "png.h"
-
-struct BufState {
-  const uint8_t* data;
-  size_t bytes_left;
-};
-
-struct PngObjectHandler {
-  png_infop info_ptr = nullptr;
-  png_structp png_ptr = nullptr;
-  png_infop end_info_ptr = nullptr;
-  png_voidp row_ptr = nullptr;
-  BufState* buf_state = nullptr;
-
-  ~PngObjectHandler() {
-    if (row_ptr)
-      png_free(png_ptr, row_ptr);
-    if (end_info_ptr)
-      png_destroy_read_struct(&png_ptr, &info_ptr, &end_info_ptr);
-    else if (info_ptr) 
-      png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
-    else
-      png_destroy_read_struct(&png_ptr, nullptr, nullptr);
-    delete buf_state;
-  }
-};
-
-void user_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
-  BufState* buf_state = static_cast<BufState*>(png_get_io_ptr(png_ptr));
-  if (length > buf_state->bytes_left) {
-    png_error(png_ptr, "read error");
-  }
-  memcpy(data, buf_state->data, length);
-  buf_state->bytes_left -= length;
-  buf_state->data += length;
-}
-
-static const int kPngHeaderSize = 8;
-
-// Entry point for LibFuzzer.
-// Roughly follows the libpng book example:
-// http://www.libpng.org/pub/png/book/chapter13.html
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  if (size < kPngHeaderSize) {
-    return 0;
-  }
-
-  std::vector<unsigned char> v(data, data + size);
-  if (png_sig_cmp(v.data(), 0, kPngHeaderSize)) {
-    // not a PNG.
-    return 0;
-  }
-
-  PngObjectHandler png_handler;
-  png_handler.png_ptr = nullptr;
-  png_handler.row_ptr = nullptr;
-  png_handler.info_ptr = nullptr;
-  png_handler.end_info_ptr = nullptr;
-
-  png_handler.png_ptr = png_create_read_struct
-    (PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
-  if (!png_handler.png_ptr) {
-    return 0;
-  }
-
-#define PNG_CLEANUP \
-  if(png_handler.png_ptr) \
-  { \
-    if (png_handler.row_ptr) \
-      png_free(png_handler.png_ptr, png_handler.row_ptr); \
-    if (png_handler.end_info_ptr) \
-      png_destroy_read_struct(&png_handler.png_ptr, &png_handler.info_ptr,\
-        &png_handler.end_info_ptr); \
-    else if (png_handler.info_ptr) \
-      png_destroy_read_struct(&png_handler.png_ptr, &png_handler.info_ptr,\
-        nullptr); \
-    else \
-      png_destroy_read_struct(&png_handler.png_ptr, nullptr, nullptr); \
-    png_handler.png_ptr = nullptr; \
-    png_handler.row_ptr = nullptr; \
-    png_handler.info_ptr = nullptr; \
-    png_handler.end_info_ptr = nullptr; \
-  }
-
-  png_handler.info_ptr = png_create_info_struct(png_handler.png_ptr);
-  if (!png_handler.info_ptr) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  png_handler.end_info_ptr = png_create_info_struct(png_handler.png_ptr);
-  if (!png_handler.end_info_ptr) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  /* Treat benign errors as warnings */
-  png_set_benign_errors(png_handler.png_ptr, 1);
-
-  png_set_crc_action(png_handler.png_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
-
-#ifdef PNG_IGNORE_ADLER32
-  png_set_option(png_handler.png_ptr, PNG_IGNORE_ADLER32, PNG_OPTION_ON);
-#endif
-
-  // Setting up reading from buffer.
-  png_handler.buf_state = new BufState();
-  png_handler.buf_state->data = data + kPngHeaderSize;
-  png_handler.buf_state->bytes_left = size - kPngHeaderSize;
-  png_set_read_fn(png_handler.png_ptr, png_handler.buf_state, user_read_data);
-  png_set_sig_bytes(png_handler.png_ptr, kPngHeaderSize);
-
-  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  // Reading.
-  png_read_info(png_handler.png_ptr, png_handler.info_ptr);
-  png_read_update_info(png_handler.png_ptr, png_handler.info_ptr);
-  png_handler.row_ptr = png_malloc(
-      png_handler.png_ptr, png_get_rowbytes(png_handler.png_ptr,
-                                               png_handler.info_ptr));
-
-  // reset error handler to put png_deleter into scope.
-  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  png_uint_32 width, height;
-  int bit_depth, color_type, interlace_type, compression_type;
-  int filter_type;
-
-  if (!png_get_IHDR(png_handler.png_ptr, png_handler.info_ptr, &width,
-                    &height, &bit_depth, &color_type, &interlace_type,
-                    &compression_type, &filter_type)) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  // This is going to be too slow.
-  if (width && height > 100000000 / width) {
-    PNG_CLEANUP
-    return 0;
-  }
-
-  int passes = png_set_interlace_handling(png_handler.png_ptr);
-  png_start_read_image(png_handler.png_ptr);
-
-  /* To do: prevent the optimizer from removing this code entirely */
-  for (int pass = 0; pass < passes; ++pass) {
-    for (png_uint_32 y = 0; y < height; ++y) {
-      png_read_row(png_handler.png_ptr,
-                   static_cast<png_bytep>(png_handler.row_ptr), nullptr);
-    }
-  }
-
-  png_read_end(png_handler.png_ptr, png_handler.end_info_ptr);
-
-  PNG_CLEANUP
-
-  /* TO do: exercise the progressive reader here */
-
-  return 0;
-}
--- a/contrib/oss-fuzz/png.dict
+++ b/contrib/oss-fuzz/png.dict
@@ -1,39 +0,0 @@
-#
-# AFL dictionary for PNG images
-# -----------------------------
-#
-# Just the basic, standard-originating sections; does not include vendor
-# extensions.
-#
-# Created by Michal Zalewski <lcamtuf@google.com>
-#
-
-header_png="\x89PNG\x0d\x0a\x1a\x0a"
-
-section_IDAT="IDAT"
-section_IEND="IEND"
-section_IHDR="IHDR"
-section_PLTE="PLTE"
-section_bKGD="bKGD"
-section_cHRM="cHRM"
-section_eXIf="eXIf"
-section_fRAc="fRAc"
-section_gAMA="gAMA"
-section_gIFg="gIFg"
-section_gIFt="gIFt"
-section_gIFx="gIFx"
-section_hIST="hIST"
-section_iCCP="iCCP"
-section_iTXt="iTXt"
-section_oFFs="oFFs"
-section_pCAL="pCAL"
-section_pHYs="pHYs"
-section_sBIT="sBIT"
-section_sCAL="sCAL"
-section_sPLT="sPLT"
-section_sRGB="sRGB"
-section_sTER="sTER"
-section_tEXt="tEXt"
-section_tIME="tIME"
-section_tRNS="tRNS"
-section_zTXt="zTXt"
--- a/contrib/pngminus/README
+++ b/contrib/pngminus/README
@@ -146,7 +146,7 @@ The Turbo bug
 The end
 -------
 Willem van Schaik
-mailto:willem at schaik.com
+mailto:willem@schaik.com
 http://www.schaik.com/png/
 -------
 Oct 1999
--- a/contrib/pngminus/png2pnm.c
+++ b/contrib/pngminus/png2pnm.c
@@ -1,12 +1,8 @@
 /*
 *  png2pnm.c --- conversion from PNG-file to PGM/PPM-file
- *  copyright (C) 1999,2017 by Willem van Schaik <willem at schaik.com>
+ *  copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
 *
 *  version 1.0 - 1999.10.15 - First version.
- *          1.1 - 2017.04.22 - Add buffer-size check (Glenn Randers-Pehrson)
- *          1.2 - 2017.08.24 - Fix potential overflow in buffer-size check
- *                             (Glenn Randers-Pehrson)
- *          1.3 - 2017.08.28 - Add PNGMINUS_UNUSED (Christian Hesse)
 *
 *  Permission to use, copy, modify, and distribute this software and
 *  its documentation for any purpose and without fee is hereby granted,
@@ -45,7 +41,6 @@
 #define PNG_DEBUG 0
 #endif

-
 #include "png.h"

 /* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
@@ -53,14 +48,6 @@
 #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
 #endif

-#ifndef PNGMINUS_UNUSED
-/* Unused formal parameter warnings are silenced using the following macro
- * which is expected to have no bad effects on performance (optimizing
- * compilers will probably remove it entirely).
- */
-#  define PNGMINUS_UNUSED(param) (void)param
-#endif
-
 /* function prototypes */

 int  main (int argc, char *argv[]);
@@ -333,21 +320,14 @@ BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
  /* row_bytes is the width x number of channels x (bit-depth / 8) */
  row_bytes = png_get_rowbytes (png_ptr, info_ptr);

-  if ((row_bytes == 0 || (size_t)height > ((size_t)(-1))/(size_t)row_bytes))
-  {
-    /* too big */ 
-    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-    return FALSE;
-  }
  if ((png_pixels = (png_byte *)
-     malloc ((size_t)row_bytes * (size_t)height * sizeof (png_byte))) == NULL)
-  {
+     malloc (row_bytes * height * sizeof (png_byte))) == NULL) {
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
    return FALSE;
  }

  if ((row_pointers = (png_byte **)
-     malloc ((size_t)height * sizeof (png_bytep))) == NULL)
+     malloc (height * sizeof (png_bytep))) == NULL)
  {
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
    free (png_pixels);
@@ -428,8 +408,7 @@ BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
          if (raw)
            fputc ((int) *pix_ptr++ , alpha_file);
          else
-            if (bit_depth == 16)
-            {
+            if (bit_depth == 16){
              dep_16 = (long) *pix_ptr++;
              fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);
            }
@@ -453,7 +432,6 @@ BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
  if (png_pixels != (unsigned char*) NULL)
    free (png_pixels);

-  PNGMINUS_UNUSED(raw); /* to quiet a Coverity defect */
  return TRUE;

 } /* end of source */
--- a/contrib/pngminus/pnm2png.c
+++ b/contrib/pngminus/pnm2png.c
@@ -1,13 +1,9 @@
 /*
 *  pnm2png.c --- conversion from PBM/PGM/PPM-file to PNG-file
- *  copyright (C) 1999,2015,2017 by Willem van Schaik <willem at schaik.com>
+ *  copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
 *
 *  version 1.0 - 1999.10.15 - First version.
 *  version 1.1 - 2015.07.29 - Fixed leaks (Glenn Randers-Pehrson)
- *  version 1.2 - 2017.04.22 - Add buffer-size check
- *          1.3 - 2017.08.24 - Fix potential overflow in buffer-size check
- *                             (Glenn Randers-Pehrson)
- *          1.4 - 2017.08.28 - Add PNGMINUS_UNUSED (Christian Hesse)
 *
 *  Permission to use, copy, modify, and distribute this software and
 *  its documentation for any purpose and without fee is hereby granted,
@@ -51,15 +47,6 @@
 #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
 #endif

-#ifndef PNGMINUS_UNUSED
-/* Unused formal parameter warnings are silenced using the following macro
- * which is expected to have no bad effects on performance (optimizing
- * compilers will probably remove it entirely).
- */
-#  define PNGMINUS_UNUSED(param) (void)param
-#endif
-
-
 /* function prototypes */

 int  main (int argc, char *argv[]);
@@ -383,16 +370,11 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
    row_bytes = (width * channels * bit_depth + 7) / 8;
  else
 #endif
-  /* row_bytes is the width x number of channels x (bit-depth / 8) */
+    /* row_bytes is the width x number of channels x (bit-depth / 8) */
    row_bytes = width * channels * ((bit_depth <= 8) ? 1 : 2);

-  if ((row_bytes == 0 || (size_t)height > ((size_t)(-1))/(size_t)row_bytes))
-  {
-    /* too big */ 
-    return FALSE;
-  }
  if ((png_pixels = (png_byte *)
-     malloc ((size_t)row_bytes * (size_t)height * sizeof (png_byte))) == NULL)
+     malloc (row_bytes * height * sizeof (png_byte))) == NULL)
    return FALSE;

  /* read data from PNM file */
@@ -401,8 +383,7 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
  for (row = 0; row < (int) height; row++)
  {
 #if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
-    if (packed_bitmap)
-    {
+    if (packed_bitmap) {
      for (i = 0; i < (int) row_bytes; i++)
        /* png supports this format natively so no conversion is needed */
        *pix_ptr++ = get_data (pnm_file, 8);
@@ -523,8 +504,6 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
  if (png_pixels != (unsigned char*) NULL)
    free (png_pixels);

-  PNGMINUS_UNUSED(raw); /* Quiet a Coverity defect */
-
  return TRUE;
 } /* end of pnm2png */

@@ -541,8 +520,7 @@ void get_token(FILE *pnm_file, char *token)
  do
  {
    ret = fgetc(pnm_file);
-    if (ret == '#')
-    {
+    if (ret == '#') {
      /* the rest of this line is a comment */
      do
      {
--- a/contrib/pngsuite/README
+++ b/contrib/pngsuite/README
@@ -101,5 +101,5 @@ Testing basn6a16.png: PASS (1072 zero samples)
 libpng passes test

 Willem van Schaik
-<willem at schaik.com>
+<willem@schaik.com>
 October 1999
--- a/contrib/powerpc-vsx/README
+++ b/contrib/powerpc-vsx/README
@@ -1,81 +0,0 @@
-OPERATING SYSTEM SPECIFIC POWERPC DETECTION
--------------------------------------------
-
-Detection of the ability to execute POWERPC on processor requires
-operating system support.  (The information is not available in user mode.)
-
-Currently only this feature is supported only for linux platform.
-
-HOW TO USE THIS
---------------
-
-This directory contains C code fragments that can be included in powerpc/powerpc_init.c
-by setting the macro PNG_POWERPC_VSX_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 arm/arm_init.o with the required macro definition.
-
-For any of this code to be used the POWERPC code must be enabled and run time
-checks must be supported.  I.e.:
-
-#if PNG_POWERPC_VSX_OPT > 0
-#ifdef PNG_POWERPC_VSX_CHECK_SUPPORTED
-
-This is done in a 'configure' build by passing configure the argument:
-
-   --enable-powerpc-vsx=check
-
-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_vsx(png_structp png_ptr);
-
-That function must return 1 if ARM NEON 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/powerpc-vsx/linux.c
+++ b/contrib/powerpc-vsx/linux.c
@@ -1,57 +0,0 @@
-/* contrib/powerpc-vsx/linux.c
- *
- * Copyright (c) 2017 Glenn Randers-Pehrson
- * Written by Vadim Barkov, 2017.
- * Last changed in libpng 1.6.29 [March 16, 2017]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- *
- * STATUS: TESTED
- * BUG REPORTS: png-mng-implement@sourceforge.net
- *
- * png_have_vsx 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>
-#include "png.h"
-
-#ifndef MAXLINE
-#  define MAXLINE 1024
-#endif
-
-static int
-png_have_vsx(png_structp png_ptr)
-{
-   FILE *f;
-
-   const char *string = "altivec supported";
-   char input[MAXLINE];
-   char *token = NULL;
-
-   PNG_UNUSED(png_ptr)
-
-   f = fopen("/proc/cpuinfo", "r");
-   if (f != NULL)
-   {
-      memset(input,0,MAXLINE);
-      while(fgets(input,MAXLINE,f) != NULL)
-      {
-         token = strstr(input,string);
-         if(token != NULL)
-            return 1;
-      }
-   }
-#ifdef PNG_WARNINGS_SUPPORTED
-   else
-      png_warning(png_ptr, "/proc/cpuinfo open failed");
-#endif
-   return 0;
-}
--- a/contrib/powerpc-vsx/linux_aux.c
+++ b/contrib/powerpc-vsx/linux_aux.c
@@ -1,36 +0,0 @@
-/* contrib/powerpc-vsx/linux_aux.c
- *
- * Copyright (c) 2017 Glenn Randers-Pehrson
- * Written by Vadim Barkov, 2017.
- * Last changed in libpng 1.6.29 [March 16, 2017]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- *
- * STATUS: TESTED
- * BUG REPORTS: png-mng-implement@sourceforge.net
- *
- * png_have_vsx implemented for Linux by using the auxiliary vector mechanism.
- *
- * 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 "sys/auxv.h"
-#include "png.h"
-
-static int
-png_have_vsx(png_structp png_ptr)
-{
-
-   const unsigned long auxv = getauxval( AT_HWCAP );
-
-   PNG_UNUSED(png_ptr)
-
-   if(auxv & (PPC_FEATURE_HAS_ALTIVEC|PPC_FEATURE_HAS_VSX ))
-      return 1;
-   else
-      return 0;
-}
-
--- a/contrib/testpngs/crashers/bad_iCCP.png
+++ b/contrib/testpngs/crashers/bad_iCCP.png
--- a/contrib/testpngs/crashers/badadler.png
+++ b/contrib/testpngs/crashers/badadler.png
--- a/contrib/testpngs/crashers/badcrc.png
+++ b/contrib/testpngs/crashers/badcrc.png
--- a/contrib/testpngs/crashers/empty_ancillary_chunks.png
+++ b/contrib/testpngs/crashers/empty_ancillary_chunks.png
--- a/contrib/testpngs/crashers/huge_IDAT.png
+++ b/contrib/testpngs/crashers/huge_IDAT.png
--- a/contrib/testpngs/crashers/huge_bKGD_chunk.png
+++ b/contrib/testpngs/crashers/huge_bKGD_chunk.png
--- a/contrib/testpngs/crashers/huge_cHRM_chunk.png
+++ b/contrib/testpngs/crashers/huge_cHRM_chunk.png
--- a/contrib/testpngs/crashers/huge_eXIf_chunk.png
+++ b/contrib/testpngs/crashers/huge_eXIf_chunk.png
--- a/contrib/testpngs/crashers/huge_gAMA_chunk.png
+++ b/contrib/testpngs/crashers/huge_gAMA_chunk.png
--- a/contrib/testpngs/crashers/huge_hIST_chunk.png
+++ b/contrib/testpngs/crashers/huge_hIST_chunk.png
--- a/contrib/testpngs/crashers/huge_iCCP_chunk.png
+++ b/contrib/testpngs/crashers/huge_iCCP_chunk.png
--- a/contrib/testpngs/crashers/huge_iTXt_chunk.png
+++ b/contrib/testpngs/crashers/huge_iTXt_chunk.png
--- a/contrib/testpngs/crashers/huge_juNK_unsafe_to_copy.png
+++ b/contrib/testpngs/crashers/huge_juNK_unsafe_to_copy.png
--- a/contrib/testpngs/crashers/huge_juNk_safe_to_copy.png
+++ b/contrib/testpngs/crashers/huge_juNk_safe_to_copy.png
--- a/contrib/testpngs/crashers/huge_pCAL_chunk.png
+++ b/contrib/testpngs/crashers/huge_pCAL_chunk.png
--- a/contrib/testpngs/crashers/huge_pHYs_chunk.png
+++ b/contrib/testpngs/crashers/huge_pHYs_chunk.png
--- a/contrib/testpngs/crashers/huge_sCAL_chunk.png
+++ b/contrib/testpngs/crashers/huge_sCAL_chunk.png
--- a/contrib/testpngs/crashers/huge_sPLT_chunk.png
+++ b/contrib/testpngs/crashers/huge_sPLT_chunk.png
--- a/contrib/testpngs/crashers/huge_sRGB_chunk.png
+++ b/contrib/testpngs/crashers/huge_sRGB_chunk.png
--- a/contrib/testpngs/crashers/huge_sTER_chunk.png
+++ b/contrib/testpngs/crashers/huge_sTER_chunk.png
--- a/contrib/testpngs/crashers/huge_tEXt_chunk.png
+++ b/contrib/testpngs/crashers/huge_tEXt_chunk.png
--- a/contrib/testpngs/crashers/huge_tIME_chunk.png
+++ b/contrib/testpngs/crashers/huge_tIME_chunk.png
--- a/contrib/testpngs/crashers/huge_zTXt_chunk.png
+++ b/contrib/testpngs/crashers/huge_zTXt_chunk.png
--- a/contrib/testpngs/makepngs.sh
+++ b/contrib/testpngs/makepngs.sh
@@ -5,7 +5,7 @@

 # Copyright (c) 2015 John Cunningham Bowler

-# Last changed in libpng 1.6.20 [December 3, 2015]
+# Last changed in libpng 1.7.0 [(PENDING RELEASE)]

 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
--- a/contrib/tools/README.txt
+++ b/contrib/tools/README.txt
@@ -23,5 +23,4 @@ ORIGINAL AUTHORS
    of the people below claim any rights with regard to the contents of this
    directory.

-    John Bowler <jbowler at acm.org>
-    Glenn Randers-Pehrson <glennrp at users.sourceforge.net>
+    John Bowler <jbowler@acm.org>
--- 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/genpng.c
+++ b/contrib/tools/genpng.c
@@ -1,8 +1,7 @@
 /*- genpng
 *
 * COPYRIGHT: Written by John Cunningham Bowler, 2015.
- * Revised by Glenn Randers-Pehrson, 2017, to add buffer-size check.
- * To the extent possible under law, the authors have waived all copyright and
+ * 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.
 *
@@ -784,19 +783,6 @@ main(int argc, const char **argv)
         return 1;
      }

-#if 1
-     /* TO do: determine whether this guard against overflow is necessary.
-      * This comment in png.h indicates that it should be safe: "libpng will
-      * refuse to process an image where such an overflow would occur", but
-      * I don't see where the image gets rejected when the buffer is too
-      * large before the malloc is attempted.
-      */
-      if (image.height > ((size_t)(-1))/(8*image.width)) {
-         fprintf(stderr, "genpng: image buffer would be too big");
-         return 1;
-      }
-#endif
-
      /* Create the buffer: */
      buffer = malloc(PNG_IMAGE_SIZE(image));

--- a/contrib/tools/pngcp.c
+++ b/contrib/tools/pngcp.c
--- a/contrib/tools/pngfix.c
+++ b/contrib/tools/pngfix.c
@@ -1,7 +1,8 @@
 /* pngfix.c
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- * Copyright (c) 2014-2017 John Cunningham Bowler
+ * Copyright (c) 2014-2016 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.21 [January 15, 2016]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -1823,7 +1824,7 @@ IDAT_init(struct IDAT * const idat, struct file * const file)
 }

 static png_uint_32
-rechunk_length(struct IDAT *idat, int start)
+rechunk_length(struct IDAT *idat)
   /* Return the length for the next IDAT chunk, taking into account
    * rechunking.
    */
@@ -1835,7 +1836,7 @@ rechunk_length(struct IDAT *idat, int start)
      const struct IDAT_list *cur;
      unsigned int count;

-      if (start)
+      if (idat->idat_index == 0) /* at the new chunk (first time) */
         return idat->idat_length; /* use the cache */

      /* Otherwise rechunk_length is called at the end of a chunk for the length
@@ -1994,7 +1995,7 @@ process_IDAT(struct file *file)
      idat->idat_index = 0; /* Index into chunk data */

      /* Update the chunk length to the correct value for the IDAT chunk: */
-      file->chunk->chunk_length = rechunk_length(idat, 1/*start*/);
+      file->chunk->chunk_length = rechunk_length(idat);

      /* Change the state to writing IDAT chunks */
      file->state = STATE_IDAT;
@@ -2415,7 +2416,7 @@ zlib_advance(struct zlib *zlib, png_uint_32 nbytes)
                  endrc = ZLIB_TOO_FAR_BACK;
                  break;
               }
-               /* FALLTHROUGH */
+               /* FALL THROUGH */

            default:
               zlib_message(zlib, 0/*stream error*/);
@@ -2569,7 +2570,7 @@ zlib_run(struct zlib *zlib)
                  list->lengths[i] -= zlib->extra_bytes;
                  list->count = i+1;
                  zlib->idat->idat_list_tail = list;
-                  /* FALLTHROUGH */
+                  /* FALL THROUGH */

               default:
                  return rc;
@@ -2672,7 +2673,7 @@ zlib_check(struct file *file, png_uint_32 offset)
            /* Truncated stream; unrecoverable, gets converted to ZLIB_FATAL */
            zlib.z.msg = PNGZ_MSG_CAST("[truncated]");
            zlib_message(&zlib, 0/*expected*/);
-            /* FALLTHROUGH */
+            /* FALL THROUGH */

         default:
            /* Unrecoverable error; skip the chunk; a zlib_message has already
@@ -3340,7 +3341,7 @@ read_callback(png_structp png_ptr, png_bytep buffer, size_t count)
               if (file->state != STATE_IDAT && length > 0)
                  setpos(chunk);
            }
-            /* FALLTHROUGH */
+            /* FALL THROUGH */

         default:
            assert(chunk != NULL);
@@ -3472,8 +3473,7 @@ read_callback(png_structp png_ptr, png_bytep buffer, size_t count)
                     /* Write another IDAT chunk.  Call rechunk_length to
                      * calculate the length required.
                      */
-                     length = chunk->chunk_length =
-                         rechunk_length(file->idat, 0/*end*/);
+                     length = chunk->chunk_length = rechunk_length(file->idat);
                     assert(type == png_IDAT);
                     file->write_count = 0; /* for the new chunk */
                     --(file->write_count); /* fake out the increment below */
--- 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/contrib/tools/sRGB.h
+++ b/contrib/tools/sRGB.h
@@ -14,7 +14,7 @@
 * All routines take and return a floating point value in the range
 * 0 to 1.0, doing a calculation according to the sRGB specification
 * (in fact the source of the numbers is the wikipedia article at
- * https://en.wikipedia.org/wiki/SRGB).
+ * http://en.wikipedia.org/wiki/SRGB).
 */
 static double
 sRGB_from_linear(double l)
--- a/contrib/visupng/PngFile.c
+++ b/contrib/visupng/PngFile.c
@@ -2,7 +2,7 @@
 *  PNGFILE.C -- Image File Functions
 *-------------------------------------
 *
- * Copyright 2000,2017 Willem van Schaik.
+ * Copyright 2000, Willem van Schaik.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -236,10 +236,6 @@ BOOL PngLoadImage (PTSTR pstrFileName, png_byte **ppbImageData,
            free (pbImageData);
            pbImageData = NULL;
        }
-        if ((*piHeight) > ((size_t)(-1))/ulRowBytes) {
-        {
-            png_error(png_ptr, "Visual PNG: image is too big");
-        }
        if ((pbImageData = (png_byte *) malloc(ulRowBytes * (*piHeight)
                            * sizeof(png_byte))) == NULL)
        {
--- a/contrib/visupng/VisualPng.c
+++ b/contrib/visupng/VisualPng.c
@@ -2,7 +2,7 @@
 *  VisualPng.C -- Shows a PNG image
 *------------------------------------
 *
- * Copyright 2000,2017 Willem van Schaik.
+ * Copyright 2000, Willem van Schaik.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -726,10 +726,6 @@ BOOL DisplayImage (HWND hwnd, BYTE **ppDib,
        pDib = NULL;
    }

-    if (cyWinSize > ((size_t)(-1))/wDIRowBytes) {
-    {
-        MessageBox (hwnd, TEXT ("Visual PNG: image is too big");
-    }
    if (!(pDib = (BYTE *) malloc (sizeof(BITMAPINFOHEADER) +
        wDIRowBytes * cyWinSize)))
    {
@@ -851,10 +847,6 @@ BOOL FillBitmap (
            cxImgPos = (cxWinSize - cxNewSize) / 2;
        }

-        if (cyNewSize > ((size_t)(-1))/(cImgChannels * cxNewSize)) {
-        {
-            MessageBox (hwnd, TEXT ("Visual PNG: stretched image is too big");
-        }
        pStretchedImage = malloc (cImgChannels * cxNewSize * cyNewSize);
        pImg = pStretchedImage;

--- 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);
@@ -114,13 +114,13 @@ int main(int argc, const char **argv)

         else
         {
-            /* Calling png_image_free is optional unless the simplified API was
+            /* Calling png_free_image is optional unless the simplified API was
             * not run to completion.  In this case if there wasn't enough
             * memory for 'buffer' we didn't complete the read, so we must free
             * the image:
             */
            if (buffer == NULL)
-               png_image_free(&image);
+               png_free_image(&image);

            else
               free(buffer);
@@ -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
@@ -983,21 +983,16 @@ void write_png(char *file_name /* , ... other image information ... */)
   png_uint_32 k, height, width;

   /* In this example, "image" is a one-dimensional array of bytes */
-
-   /* Guard against integer overflow */
-   if (height > PNG_SIZE_MAX/(width*bytes_per_pixel)) {
-      png_error(png_ptr, "Image_data buffer would be too large");
-   }
   png_byte image[height*width*bytes_per_pixel];

   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/intel/filter_sse2_intrinsics.c
+++ b/intel/filter_sse2_intrinsics.c
@@ -1,406 +0,0 @@
-
-/* filter_sse2_intrinsics.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016-2017 Glenn Randers-Pehrson
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/filter_neon_intrinsics.c
- *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- *
- * 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 = (png_const_uint_16p)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;
-   png_uint_16* p01;
-   png_byte*    p2;
-
-   store4(&v012, v);
-
-   p01 = (png_uint_16p)p;
-   p2  = (png_byte*)(p01+1);
-   *p01 = (png_uint_16)v012;
-   *p2  = (png_byte)(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_size_t rb;
-
-   __m128i a, d = _mm_setzero_si128();
-
-   png_debug(1, "in png_read_filter_row_sub3_sse2");
-
-   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;
-   }
-   PNG_UNUSED(prev)
-}
-
-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_size_t rb;
-
-   __m128i a, d = _mm_setzero_si128();
-
-   png_debug(1, "in png_read_filter_row_sub4_sse2");
-
-   rb = row_info->rowbytes+4;
-   while (rb > 4) {
-      a = d; d = load4(row);
-      d = _mm_add_epi8(d, a);
-      store4(row, d);
-
-      row += 4;
-      rb  -= 4;
-   }
-   PNG_UNUSED(prev)
-}
-
-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_size_t rb;
-
-   const __m128i zero = _mm_setzero_si128();
-
-   __m128i    b;
-   __m128i a, d = zero;
-
-   png_debug(1, "in png_read_filter_row_avg3_sse2");
-   rb = row_info->rowbytes;
-   while (rb >= 4) {
-      __m128i avg;
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      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) {
-      __m128i avg;
-             b = load3(prev);
-      a = d; d = load3(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      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_size_t rb;
-   const __m128i zero = _mm_setzero_si128();
-   __m128i    b;
-   __m128i a, d = zero;
-
-   png_debug(1, "in png_read_filter_row_avg4_sse2");
-
-   rb = row_info->rowbytes+4;
-   while (rb > 4) {
-      __m128i avg;
-             b = load4(prev);
-      a = d; d = load4(row );
-
-      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      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_size_t rb;
-   const __m128i zero = _mm_setzero_si128();
-   __m128i c, b = zero,
-           a, d = zero;
-
-   png_debug(1, "in png_read_filter_row_paeth3_sse2");
-
-   rb = row_info->rowbytes;
-   while (rb >= 4) {
-      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
-       * intermediates.
-       */
-      __m128i pa,pb,pc,smallest,nearest;
-      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) */
-   
-      pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      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.
-       */
-      __m128i pa,pb,pc,smallest,nearest;
-      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) */
-      pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      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_size_t rb;
-   const __m128i zero = _mm_setzero_si128();
-   __m128i pa,pb,pc,smallest,nearest;
-   __m128i c, b = zero,
-           a, d = zero;
-
-   png_debug(1, "in png_read_filter_row_paeth4_sse2");
-
-   rb = row_info->rowbytes+4;
-   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) */
-      pa = _mm_sub_epi16(b,c);
-
-      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
-
-      /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
-      pc = _mm_add_epi16(pa,pb);
-
-      pa = abs_i16(pa);  /* |p-a| */
-      pb = abs_i16(pb);  /* |p-b| */
-      pc = abs_i16(pc);  /* |p-c| */
-
-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
-      /* Paeth breaks ties favoring a over b over c. */
-      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/intel/intel_init.c
+++ b/intel/intel_init.c
@@ -1,53 +0,0 @@
-
-/* intel_init.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016-2017 Glenn Randers-Pehrson
- * Written by Mike Klein and Matt Sarett, Google, Inc.
- * Derived from arm/arm_init.c
- *
- * Last changed in libpng 1.6.29 [March 16, 2017]
- *
- * 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/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,9 +1,9 @@
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.34 - September 29, 2017
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson

 This document is released under the libpng license.
 For conditions of distribution and use, see the disclaimer
@@ -11,9 +11,9 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.34 - September 29, 2017
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson

 libpng 1.0 beta 6 - version 0.96 - May 28, 1997
 Updated and distributed by Andreas Dilger
@@ -66,17 +66,17 @@ file format in application programs.

 The PNG specification (second edition), November 2003, is available as
 a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
-<https://www.w3.org/TR/2003/REC-PNG-20031110/
+<http://www.w3.org/TR/2003/REC-PNG-20031110/
 The W3C and ISO documents have identical technical content.

 The PNG-1.2 specification is available at
-<https://png-mng.sourceforge.io/pub/png/spec/1.2/>.
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
 It is technically equivalent
 to the PNG specification (second edition) but has some additional material.

-The PNG-1.0 specification is available as RFC 2083
-<https://png-mng.sourceforge.io/pub/png/spec/1.0/> and as a
-W3C Recommendation <https://www.w3.org/TR/REC-png-961001>.
+The PNG-1.0 specification is available as RFC 2083 
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.

 Some additional chunks are described in the special-purpose public chunks
 documents at <http://www.libpng.org/pub/png/spec/register/>
@@ -101,7 +101,7 @@ majority of the needs of its users.

 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <https://zlib.net/>.
+be found at the zlib home page, <http://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@@ -467,9 +467,8 @@ the default, use

 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
-is handled while reading the IDAT chunk. Note that it is impossible to
-"discard" data in a critical chunk.
+therein.  Note that it is impossible to "discard" data in a critical
+chunk.

 Choices for (int) crit_action are
   PNG_CRC_DEFAULT      0  error/quit
@@ -486,9 +485,6 @@ Choices for (int) ancil_action are
   PNG_CRC_QUIET_USE    4  quiet/use data
   PNG_CRC_NO_CHANGE    5  use the current value

-When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
-checksums are not only ignored, but they are not evaluated.
-
 Setting up callback code

 You can set up a callback function to handle any unknown chunks in the
@@ -563,7 +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.

@@ -688,9 +684,8 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
   chunk_cache_max = png_get_chunk_cache_max(png_ptr);

 Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that any chunk other than IDAT can occupy, originally or when
-decompressed (prior to libpng-1.6.32 the limit was only applied to compressed
-chunks after decompression). You can change this limit with
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with

   png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);

@@ -986,17 +981,8 @@ premultiplication.

    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);

-Choices for the alpha_mode are
-
-    PNG_ALPHA_PNG           0 /* according to the PNG standard */
-    PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
-    PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
-    PNG_ALPHA_PREMULTIPLIED 1 /* as above */
-    PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
-    PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
-
-PNG_ALPHA_PNG is the default libpng handling of the alpha channel. It is not
-pre-multiplied into the color components. In addition the call states
+This is the default libpng handling of the alpha channel - it is not
+pre-multiplied into the color components.  In addition the call states
 that the output is for a sRGB system and causes all PNG files without gAMA
 chunks to be assumed to be encoded using sRGB.

@@ -1011,7 +997,7 @@ early Mac systems behaved.
 This is the classic Jim Blinn approach and will work in academic
 environments where everything is done by the book.  It has the shortcoming
 of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files were generated locally.
+is unlikely to be correct unless the PNG files where generated locally.
 Most of the time the output precision will be so low as to show
 significant banding in dark areas of the image.

@@ -1200,20 +1186,7 @@ row_pointers prior to calling png_read_png() with
   png_set_rows(png_ptr, info_ptr, &row_pointers);

 Alternatively you could allocate your image in one big block and define
-row_pointers[i] to point into the proper places in your block, but first
-be sure that your platform is able to allocate such a large buffer:
-
-   /* Guard against integer overflow */
-   if (height > PNG_SIZE_MAX/(width*pixel_size)) {
-        png_error(png_ptr,"image_data buffer would be too large");
-   }
-
-   png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
-
-   for (int i=0; i<height, i++)
-      row_pointers[i]=buffer+i*width*pixel_size;
-
-   png_set_rows(png_ptr, info_ptr, &row_pointers);
+row_pointers[i] to point into the proper places in your block.

 If you use png_set_rows(), the application is responsible for freeing
 row_pointers (and row_pointers[i], if they were separately allocated).
@@ -1340,11 +1313,6 @@ in until png_read_end() has read the chunk data following the image.
    rowbytes = png_get_rowbytes(png_ptr, info_ptr);

    rowbytes       - number of bytes needed to hold a row
-                     This value, the bit_depth, color_type,
-                     and the number of channels can change
-                     if you use transforms such as
-                     png_set_expand(). See
-                     png_read_update_info(), below.

    signature = png_get_signature(png_ptr, info_ptr);

@@ -1463,11 +1431,6 @@ png_set_rgb_to_gray()).
                     the single transparent color for
                     non-paletted images (PNG_INFO_tRNS)

-    png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
-                     (PNG_INFO_eXIf)
-
-    exif           - Exif profile (array of png_byte)
-
    png_get_hIST(png_ptr, info_ptr, &hist);
                     (PNG_INFO_hIST)

@@ -2179,16 +2142,6 @@ are allocating one large chunk, you will need to build an
 array of pointers to each row, as it will be needed for some
 of the functions below.

-Be sure that your platform can allocate the buffer that you'll need.
-libpng internally checks for oversize width, but you'll need to
-do your own check for number_of_rows*width*pixel_size if you are using
-a multiple-row buffer:
-
-   /* Guard against integer overflow */
-   if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
-        png_error(png_ptr,"image_data buffer would be too large");
-   }
-
 Remember: Before you call png_read_update_info(), the png_get_*()
 functions return the values corresponding to the original PNG image.
 After you call png_read_update_info the values refer to the image
@@ -2277,8 +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
@@ -2287,8 +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
@@ -2296,8 +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.
@@ -2513,7 +2461,6 @@ your application instead of by libpng, you can use
             PNG_INFO_gAMA, PNG_INFO_sBIT,
             PNG_INFO_cHRM, PNG_INFO_PLTE,
             PNG_INFO_tRNS, PNG_INFO_bKGD,
-             PNG_INFO_eXIf,
             PNG_INFO_hIST, PNG_INFO_pHYs,
             PNG_INFO_oFFs, PNG_INFO_tIME,
             PNG_INFO_pCAL, PNG_INFO_sRGB,
@@ -2895,7 +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
@@ -3113,11 +3060,6 @@ width, height, bit_depth, and color_type must be the same in each call.
                     single transparent color for
                     non-paletted images (PNG_INFO_tRNS)

-    png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
-
-    exif           - Exif profile (array of
-                     png_byte) (PNG_INFO_eXIf)
-
    png_set_hIST(png_ptr, info_ptr, hist);

    hist           - histogram of palette (array of
@@ -3873,7 +3815,7 @@ PNG_FORMAT_FLAG_LINEAR flag below.

 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.

 When an alpha channel is present it is expected to denote pixel coverage
@@ -4137,7 +4079,7 @@ READ APIs

 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.

 WRITE APIS
@@ -4161,13 +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)
@@ -4295,6 +4230,8 @@ functions after png_create_*_struct() has been called by calling:
        png_voidp error_ptr, png_error_ptr error_fn,
        png_error_ptr warning_fn);

+    png_voidp error_ptr = png_get_error_ptr(png_ptr);
+
 If NULL is supplied for either error_fn or warning_fn, then the libpng
 default function will be used, calling fprintf() and/or longjmp() if a
 problem is encountered.  The replacement error functions should have
@@ -4306,11 +4243,6 @@ parameters as follows:
    void user_warning_fn(png_structp png_ptr,
        png_const_charp warning_msg);

-Then, within your user_error_fn or user_warning_fn, you can retrieve
-the error_ptr if you need it, by calling
-
-    png_voidp error_ptr = png_get_error_ptr(png_ptr);
-
 The motivation behind using setjmp() and longjmp() is the C++ throw and
 catch exception handling methods.  This makes the code much easier to write,
 as there is no need to check every return code of every function call.
@@ -4318,7 +4250,7 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see https://cexcept.sourceforge.io/),
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
 which is illustrated in pngvalid.c and in contrib/visupng.

 Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
@@ -4448,9 +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
@@ -4464,19 +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
@@ -4546,7 +4470,7 @@ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
 and the MHDR and MEND chunks.  Libpng does not provide support for these
 or any other MNG chunks; your application must provide its own support for
 them.  You may wish to consider using libmng (available at
-https://www.libmng.com/) instead.
+http://www.libmng.com) instead.

 VIII.  Changes to Libpng from version 0.88

@@ -4851,8 +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
@@ -4969,14 +4892,18 @@ PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
 that it could be used to override them.  Now this function will reduce or
 increase the limits.

-Starting in libpng-1.5.22, default user limits were established. These
-can be overridden by application calls to png_set_user_limits(),
-png_set_user_chunk_cache_max(), and/or png_set_user_malloc_max().
-The limits are now
-                             max possible  default
+Starting in libpng-1.5.10, the user limits can be set en masse with the
+configuration option PNG_SAFE_LIMITS_SUPPORTED.  If this option is enabled,
+a set of "safe" limits is applied in pngpriv.h.  These can be overridden by
+application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+and/or png_set_user_malloc_max() that increase or decrease the limits.  Also,
+in libpng-1.5.10 the default width and height limits were increased
+from 1,000,000 to 0x7fffffff (i.e., made unlimited).  Therefore, the
+limits are now
+                               default      safe
   png_user_width_max        0x7fffffff    1,000,000
   png_user_height_max       0x7fffffff    1,000,000
-   png_user_chunk_cache_max  0 (unlimited) 1000
+   png_user_chunk_cache_max  0 (unlimited)   128
   png_user_chunk_malloc_max 0 (unlimited) 8,000,000

 The png_set_option() function (and the "options" member of the png struct) was
@@ -5088,7 +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
@@ -5226,11 +5152,6 @@ is an error. Previously this requirement of the PNG specification was not
 enforced, and the palette was always limited to 256 entries. An over-length
 PLTE chunk found in an input PNG is silently truncated.

-Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
-attempt to decode the Exif profile; it simply returns a byte array
-containing the profile to the calling application which must do its own
-decoding.
-
 XIII.  Detecting libpng

 The png_get_io_ptr() function has been present since libpng-0.88, has never
@@ -5247,33 +5168,27 @@ control.  The git repository was built from old libpng-x.y.z.tar.gz files
 going back to version 0.70.  You can access the git repository (read only)
 at

-    https://github.com/glennrp/libpng or
-    https://git.code.sf.net/p/libpng/code.git
+    git://git.code.sf.net/p/libpng/code

-or you can browse it with a web browser at
+or you can browse it with a web browser by selecting the "code" button at

-    https://github.com/glennrp/libpng or
-    https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
+    https://sourceforge.net/projects/libpng

 Patches can be sent to glennrp at users.sourceforge.net or to
 png-mng-implement at lists.sourceforge.net or you can upload them to
 the libpng bug tracker at

-    https://libpng.sourceforge.io/
-
-or as a "pull request" to
-
-    https://github.com/glennrp/libpng/pulls
+    http://libpng.sourceforge.net

 We also accept patches built from the tar or zip distributions, and
 simple verbal discriptions of bug fixes, reported either to the
 SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list, as github issues, or directly to glennrp.
+mailing list, or directly to glennrp.

 XV. Coding style

 Our coding style is similar to the "Allman" style
-(See https://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
 braces on separate lines:

    if (condition)
@@ -5374,7 +5289,7 @@ Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
 though it were a function.

 Control keywords if, for, while, and switch are always followed by a space
-to distinguish them from function calls, which have no trailing space.
+to distinguish them from function calls, which have no trailing space. 

 We put a space after each comma and after each semicolon
 in "for" statements, and we put spaces before and after each
@@ -5398,9 +5313,8 @@ with an even number of lower-case hex digits, and to make them unsigned
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.

-We prefer "if (something != 0)" and "if (something == 0)" over
-"if (something)" and if "(!something)", respectively, and for pointers
-we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
+We prefer "if (something != 0)" and "if (something == 0)"
+over "if (something)" and if "(!something)", respectively.

 We do not use the TAB character for indentation in the C sources.

@@ -5414,7 +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 1.6.34 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 29, 2017"
+.TH LIBPNG 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.34
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -97,10 +97,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.34

 \fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP

-\fBpng_uint_32 png_get_eXIf (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fI*exif\fP\fB);\fP
-
-\fBpng_uint_32 png_get_eXIf_1 (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unit_32 \fP\fI*num_exif\fP\fB, png_bytep \fI*exif\fP\fB);\fP
-
 \fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP

 \fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
@@ -233,8 +229,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.34

 \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
@@ -351,10 +345,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.34

 \fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP

-\fBvoid png_set_eXIf (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fIexif\fP\fB);\fP
-
-\fBvoid png_set_eXIf_1 (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, const png_uint_32 \fP\fInum_exif\fP\fB, png_bytep \fIexif\fP\fB);\fP
-
 \fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP

 \fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
@@ -518,10 +508,10 @@ 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 1.6.34 - September 29, 2017
+ libpng version 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson

 This document is released under the libpng license.
 For conditions of distribution and use, see the disclaimer
@@ -529,9 +519,9 @@ libpng-manual.txt - A description on how to use and modify libpng

 Based on:

- libpng versions 0.97, January 1998, through 1.6.34 - September 29, 2017
+ libpng versions 0.97, January 1998, through 1.6.21 - January 15, 2016
 Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson

 libpng 1.0 beta 6 - version 0.96 - May 28, 1997
 Updated and distributed by Andreas Dilger
@@ -584,17 +574,17 @@ file format in application programs.

 The PNG specification (second edition), November 2003, is available as
 a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
-<https://www.w3.org/TR/2003/REC-PNG-20031110/
+<http://www.w3.org/TR/2003/REC-PNG-20031110/
 The W3C and ISO documents have identical technical content.

 The PNG-1.2 specification is available at
-<https://png-mng.sourceforge.io/pub/png/spec/1.2/>.
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
 It is technically equivalent
 to the PNG specification (second edition) but has some additional material.

-The PNG-1.0 specification is available as RFC 2083
-<https://png-mng.sourceforge.io/pub/png/spec/1.0/> and as a
-W3C Recommendation <https://www.w3.org/TR/REC-png-961001>.
+The PNG-1.0 specification is available as RFC 2083 
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.

 Some additional chunks are described in the special-purpose public chunks
 documents at <http://www.libpng.org/pub/png/spec/register/>
@@ -619,7 +609,7 @@ majority of the needs of its users.

 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <https://zlib.net/>.
+be found at the zlib home page, <http://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@@ -985,9 +975,8 @@ the default, use

 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
-is handled while reading the IDAT chunk. Note that it is impossible to
-"discard" data in a critical chunk.
+therein.  Note that it is impossible to "discard" data in a critical
+chunk.

 Choices for (int) crit_action are
   PNG_CRC_DEFAULT      0  error/quit
@@ -1004,9 +993,6 @@ Choices for (int) ancil_action are
   PNG_CRC_QUIET_USE    4  quiet/use data
   PNG_CRC_NO_CHANGE    5  use the current value

-When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
-checksums are not only ignored, but they are not evaluated.
-
 .SS Setting up callback code

 You can set up a callback function to handle any unknown chunks in the
@@ -1081,7 +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.

@@ -1206,9 +1192,8 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
   chunk_cache_max = png_get_chunk_cache_max(png_ptr);

 Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that any chunk other than IDAT can occupy, originally or when
-decompressed (prior to libpng-1.6.32 the limit was only applied to compressed
-chunks after decompression). You can change this limit with
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with

   png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);

@@ -1504,17 +1489,8 @@ premultiplication.

    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);

-Choices for the alpha_mode are
-
-    PNG_ALPHA_PNG           0 /* according to the PNG standard */
-    PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
-    PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
-    PNG_ALPHA_PREMULTIPLIED 1 /* as above */
-    PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
-    PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
-
-PNG_ALPHA_PNG is the default libpng handling of the alpha channel. It is not
-pre-multiplied into the color components. In addition the call states
+This is the default libpng handling of the alpha channel - it is not
+pre-multiplied into the color components.  In addition the call states
 that the output is for a sRGB system and causes all PNG files without gAMA
 chunks to be assumed to be encoded using sRGB.

@@ -1529,7 +1505,7 @@ early Mac systems behaved.
 This is the classic Jim Blinn approach and will work in academic
 environments where everything is done by the book.  It has the shortcoming
 of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files were generated locally.
+is unlikely to be correct unless the PNG files where generated locally.
 Most of the time the output precision will be so low as to show
 significant banding in dark areas of the image.

@@ -1718,20 +1694,7 @@ row_pointers prior to calling png_read_png() with
   png_set_rows(png_ptr, info_ptr, &row_pointers);

 Alternatively you could allocate your image in one big block and define
-row_pointers[i] to point into the proper places in your block, but first
-be sure that your platform is able to allocate such a large buffer:
-
-   /* Guard against integer overflow */
-   if (height > PNG_SIZE_MAX/(width*pixel_size)) {
-        png_error(png_ptr,"image_data buffer would be too large");
-   }
-
-   png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
-
-   for (int i=0; i<height, i++)
-      row_pointers[i]=buffer+i*width*pixel_size;
-
-   png_set_rows(png_ptr, info_ptr, &row_pointers);
+row_pointers[i] to point into the proper places in your block.

 If you use png_set_rows(), the application is responsible for freeing
 row_pointers (and row_pointers[i], if they were separately allocated).
@@ -1858,11 +1821,6 @@ in until png_read_end() has read the chunk data following the image.
    rowbytes = png_get_rowbytes(png_ptr, info_ptr);

    rowbytes       - number of bytes needed to hold a row
-                     This value, the bit_depth, color_type,
-                     and the number of channels can change
-                     if you use transforms such as
-                     png_set_expand(). See
-                     png_read_update_info(), below.

    signature = png_get_signature(png_ptr, info_ptr);

@@ -1981,11 +1939,6 @@ png_set_rgb_to_gray()).
                     the single transparent color for
                     non-paletted images (PNG_INFO_tRNS)

-    png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
-                     (PNG_INFO_eXIf)
-
-    exif           - Exif profile (array of png_byte)
-
    png_get_hIST(png_ptr, info_ptr, &hist);
                     (PNG_INFO_hIST)

@@ -2697,16 +2650,6 @@ are allocating one large chunk, you will need to build an
 array of pointers to each row, as it will be needed for some
 of the functions below.

-Be sure that your platform can allocate the buffer that you'll need.
-libpng internally checks for oversize width, but you'll need to
-do your own check for number_of_rows*width*pixel_size if you are using
-a multiple-row buffer:
-
-   /* Guard against integer overflow */
-   if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
-        png_error(png_ptr,"image_data buffer would be too large");
-   }
-
 Remember: Before you call png_read_update_info(), the png_get_*()
 functions return the values corresponding to the original PNG image.
 After you call png_read_update_info the values refer to the image
@@ -2795,8 +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
@@ -2805,8 +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
@@ -2814,8 +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.
@@ -3031,7 +2969,6 @@ your application instead of by libpng, you can use
             PNG_INFO_gAMA, PNG_INFO_sBIT,
             PNG_INFO_cHRM, PNG_INFO_PLTE,
             PNG_INFO_tRNS, PNG_INFO_bKGD,
-             PNG_INFO_eXIf,
             PNG_INFO_hIST, PNG_INFO_pHYs,
             PNG_INFO_oFFs, PNG_INFO_tIME,
             PNG_INFO_pCAL, PNG_INFO_sRGB,
@@ -3413,7 +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
@@ -3631,11 +3568,6 @@ width, height, bit_depth, and color_type must be the same in each call.
                     single transparent color for
                     non-paletted images (PNG_INFO_tRNS)

-    png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
-
-    exif           - Exif profile (array of
-                     png_byte) (PNG_INFO_eXIf)
-
    png_set_hIST(png_ptr, info_ptr, hist);

    hist           - histogram of palette (array of
@@ -4391,7 +4323,7 @@ PNG_FORMAT_FLAG_LINEAR flag below.

 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.

 When an alpha channel is present it is expected to denote pixel coverage
@@ -4655,7 +4587,7 @@ READ APIs

 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.

 WRITE APIS
@@ -4679,13 +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)
@@ -4813,6 +4738,8 @@ functions after png_create_*_struct() has been called by calling:
        png_voidp error_ptr, png_error_ptr error_fn,
        png_error_ptr warning_fn);

+    png_voidp error_ptr = png_get_error_ptr(png_ptr);
+
 If NULL is supplied for either error_fn or warning_fn, then the libpng
 default function will be used, calling fprintf() and/or longjmp() if a
 problem is encountered.  The replacement error functions should have
@@ -4824,11 +4751,6 @@ parameters as follows:
    void user_warning_fn(png_structp png_ptr,
        png_const_charp warning_msg);

-Then, within your user_error_fn or user_warning_fn, you can retrieve
-the error_ptr if you need it, by calling
-
-    png_voidp error_ptr = png_get_error_ptr(png_ptr);
-
 The motivation behind using setjmp() and longjmp() is the C++ throw and
 catch exception handling methods.  This makes the code much easier to write,
 as there is no need to check every return code of every function call.
@@ -4836,7 +4758,7 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see https://cexcept.sourceforge.io/),
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
 which is illustrated in pngvalid.c and in contrib/visupng.

 Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
@@ -4966,9 +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
@@ -4982,19 +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
@@ -5064,7 +4978,7 @@ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
 and the MHDR and MEND chunks.  Libpng does not provide support for these
 or any other MNG chunks; your application must provide its own support for
 them.  You may wish to consider using libmng (available at
-https://www.libmng.com/) instead.
+http://www.libmng.com) instead.

 .SH VIII.  Changes to Libpng from version 0.88

@@ -5369,8 +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
@@ -5487,14 +5400,18 @@ PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
 that it could be used to override them.  Now this function will reduce or
 increase the limits.

-Starting in libpng-1.5.22, default user limits were established. These
-can be overridden by application calls to png_set_user_limits(),
-png_set_user_chunk_cache_max(), and/or png_set_user_malloc_max().
-The limits are now
-                             max possible  default
+Starting in libpng-1.5.10, the user limits can be set en masse with the
+configuration option PNG_SAFE_LIMITS_SUPPORTED.  If this option is enabled,
+a set of "safe" limits is applied in pngpriv.h.  These can be overridden by
+application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+and/or png_set_user_malloc_max() that increase or decrease the limits.  Also,
+in libpng-1.5.10 the default width and height limits were increased
+from 1,000,000 to 0x7fffffff (i.e., made unlimited).  Therefore, the
+limits are now
+                               default      safe
   png_user_width_max        0x7fffffff    1,000,000
   png_user_height_max       0x7fffffff    1,000,000
-   png_user_chunk_cache_max  0 (unlimited) 1000
+   png_user_chunk_cache_max  0 (unlimited)   128
   png_user_chunk_malloc_max 0 (unlimited) 8,000,000

 The png_set_option() function (and the "options" member of the png struct) was
@@ -5606,7 +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
@@ -5744,11 +5660,6 @@ is an error. Previously this requirement of the PNG specification was not
 enforced, and the palette was always limited to 256 entries. An over-length
 PLTE chunk found in an input PNG is silently truncated.

-Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
-attempt to decode the Exif profile; it simply returns a byte array
-containing the profile to the calling application which must do its own
-decoding.
-
 .SH XIII.  Detecting libpng

 The png_get_io_ptr() function has been present since libpng-0.88, has never
@@ -5765,33 +5676,27 @@ control.  The git repository was built from old libpng-x.y.z.tar.gz files
 going back to version 0.70.  You can access the git repository (read only)
 at

-    https://github.com/glennrp/libpng or
-    https://git.code.sf.net/p/libpng/code.git
+    git://git.code.sf.net/p/libpng/code

-or you can browse it with a web browser at
+or you can browse it with a web browser by selecting the "code" button at

-    https://github.com/glennrp/libpng or
-    https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
+    https://sourceforge.net/projects/libpng

 Patches can be sent to glennrp at users.sourceforge.net or to
 png-mng-implement at lists.sourceforge.net or you can upload them to
 the libpng bug tracker at

-    https://libpng.sourceforge.io/
-
-or as a "pull request" to
-
-    https://github.com/glennrp/libpng/pulls
+    http://libpng.sourceforge.net

 We also accept patches built from the tar or zip distributions, and
 simple verbal discriptions of bug fixes, reported either to the
 SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list, as github issues, or directly to glennrp.
+mailing list, or directly to glennrp.

 .SH XV. Coding style

 Our coding style is similar to the "Allman" style
-(See https://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
 braces on separate lines:

    if (condition)
@@ -5892,7 +5797,7 @@ Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
 though it were a function.

 Control keywords if, for, while, and switch are always followed by a space
-to distinguish them from function calls, which have no trailing space.
+to distinguish them from function calls, which have no trailing space. 

 We put a space after each comma and after each semicolon
 in "for" statements, and we put spaces before and after each
@@ -5916,9 +5821,8 @@ with an even number of lower-case hex digits, and to make them unsigned
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.

-We prefer "if (something != 0)" and "if (something == 0)" over
-"if (something)" and if "(!something)", respectively, and for pointers
-we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
+We prefer "if (something != 0)" and "if (something == 0)"
+over "if (something)" and if "(!something)", respectively.

 We do not use the TAB character for indentation in the C sources.

@@ -5932,7 +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 1.6.34 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
@@ -6030,11 +5934,11 @@ the first widely used release:
 ...
 1.0.19                  10    10019  10.so.0.19[.0]
 ...
- 1.2.59                  13    10259  12.so.0.59[.0]
+ 1.2.53                  13    10253  12.so.0.53[.0]
 ...
- 1.5.30                  15    10530  15.so.15.30[.0]
+ 1.5.23                  15    10523  15.so.15.23[.0]
 ...
- 1.6.34                  16    10634  16.so.16.34[.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
@@ -6051,7 +5955,7 @@ release number plus "betaNN" or "rcNN".
 .LP
 .IR libpng :
 .IP
-https://libpng.sourceforge.io/ (follow the [DOWNLOAD] link)
+http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
 http://www.libpng.org/pub/png

 .LP
@@ -6061,7 +5965,7 @@ http://www.libpng.org/pub/png
 .I libpng
 or at
 .br
-https://zlib.net/
+ftp://ftp.info-zip.org/pub/infozip/zlib

 .LP
 .IR PNG specification: RFC 2083
@@ -6070,11 +5974,11 @@ https://zlib.net/
 .I libpng
 or at
 .br
-https://www.ietf.org/rfc/rfc2083.txt
+ftp://ftp.rfc-editor.org:/in-notes/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
-https://www.w3.org/TR/REC-png.html
+http://www.w3.org/TR/REC-png.html

 .LP
 In the case of any inconsistency between the PNG specification
@@ -6090,7 +5994,7 @@ possible without all of you.

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

-Libpng version 1.6.34 - September 29, 2017:
+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).

@@ -6115,8 +6019,8 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
-Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, 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
 added to the list of Contributing Authors:
@@ -6127,9 +6031,6 @@ added to the list of Contributing Authors:
   Cosmin Truta
   Gilles Vollant
   James Yu
-   Mandar Sahastrabuddhe
-   Google Inc.
-   Vadim Barkov

 and with the following additions to the disclaimer:

@@ -6140,10 +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
@@ -6167,9 +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.

@@ -6210,29 +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:

@@ -6241,9 +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 29, 2017
+January 15, 2016

 .\" end of man page

--- a/libpng.pc.in
+++ b/libpng.pc.in
@@ -6,7 +6,6 @@ includedir=@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
 Name: libpng
 Description: Loads and saves PNG files
 Version: @PNGLIB_VERSION@
-Requires: zlib
 Libs: -L${libdir} -lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
 Libs.private: @LIBS@
 Cflags: -I${includedir}
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,11 +1,11 @@
-.TH LIBPNGPF 3 "April 1, 2017"
+.TH LIBPNGPF 3 "January 15, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.34
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.21
 (private functions)
 .SH SYNOPSIS
-\fB\fB#include \fI\fI"pngpriv.h"
+\fB#include \fI"pngpriv.h"

-\fB\fBAs of libpng version \fP\fI\fP\fI1.5.1\fP\fB\fP\fB, this section is no longer \fP\fI\fP\fImaintained\fP\fB\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fI\fIfunction.
+\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fIfunction.

 .SH DESCRIPTION
 The functions previously listed here are used privately by libpng and are not
--- 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 "April 1, 2017"
+.TH PNG 5 "January 15, 2016"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
@@ -23,11 +23,11 @@ platforms.
 PNG specification (second edition), November 2003:
 .IP
 .br
-  <https://www.w3.org/TR/2003/REC-PNG-20031110/
+  <http://www.w3.org/TR/2003/REC-PNG-20031110/
 PNG 1.2 specification, July 1999:
 .IP
 .br
-https://png-mng.sourceforge.io/pub/png/spec/1.2/
+http://png-mng.sourceforge.net/pub/png/spec/1.2/
 .LP
 PNG 1.0 specification, October 1996:
 .IP
@@ -35,11 +35,11 @@ PNG 1.0 specification, October 1996:
 RFC 2083
 .IP
 .br
-https://www.ietf.org/rfc/rfc2083.txt
+ftp://ds.internic.net/rfc/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
-https://www.w3.org/TR/REC-png-961001
+http://www.w3.org/TR/REC-png-961001
 .SH AUTHORS
 This man page: Glenn Randers-Pehrson
 .LP
--- a/png.c
+++ b/png.c
--- a/png.h
+++ b/png.h
@@ -1,9 +1,9 @@

 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.34, September 29, 2017
+ * libpng version 1.6.21, January 15, 2016
 *
- * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2016 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.)
 *
@@ -12,7 +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 1.6.34, September 29, 2017:
+ *   libpng versions 0.97, January 1998, through 1.6.21, January 15, 2016:
 *     Glenn Randers-Pehrson.
 *   See also "Contributing Authors", below.
 */
@@ -25,8 +25,8 @@
 *
 * This code is released under the libpng license.
 *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
- * Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, 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
 * added to the list of Contributing Authors:
@@ -37,9 +37,6 @@
 *    Cosmin Truta
 *    Gilles Vollant
 *    James Yu
- *    Mandar Sahastrabuddhe
- *    Google Inc.
- *    Vadim Barkov
 *
 * and with the following additions to the disclaimer:
 *
@@ -50,10 +47,6 @@
 *    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
@@ -77,9 +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.
 *
@@ -119,29 +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).
 */

 /*
@@ -154,6 +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
@@ -209,11 +182,11 @@
 *    ...
 *    1.0.19                  10    10019  10.so.0.19[.0]
 *    ...
- *    1.2.59                  13    10257  12.so.0.59[.0]
+ *    1.2.53                  13    10253  12.so.0.53[.0]
 *    ...
- *    1.5.30                  15    10527  15.so.15.30[.0]
+ *    1.5.23                  15    10523  15.so.15.23[.0]
 *    ...
- *    1.6.34                  16    10633  16.so.16.34[.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
@@ -234,20 +207,20 @@
 *
 * See libpng.txt or libpng.3 for more information.  The PNG specification
 * is available as a W3C Recommendation and as an ISO Specification,
- * <https://www.w3.org/TR/2003/REC-PNG-20031110/
+ * <http://www.w3.org/TR/2003/REC-PNG-20031110/
 */

 /*
 * Y2K compliance in libpng:
 * =========================
 *
- *    September 29, 2017
+ *    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 1.6.34 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
@@ -309,8 +282,9 @@
 */

 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.34"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.34 - September 29, 2017\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
@@ -318,7 +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 34
+#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:
@@ -349,20 +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 10634 /* 1.6.34 */
+#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

@@ -459,7 +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_34;
+typedef char* png_libpng_version_1_6_21;

 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
@@ -652,17 +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;

@@ -760,23 +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_eXIf 0x10000U /* GR-P, 1.6.31 */
+#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
@@ -1347,7 +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
@@ -1498,8 +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.
@@ -1776,22 +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_EXIF 0x8000U /* Added at libpng-1.6.31 */
-#define PNG_FREE_ALL  0xffffU
-#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,
@@ -2009,18 +1983,6 @@ PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
    png_fixed_point int_blue_Z))
 #endif

-#ifdef PNG_eXIf_SUPPORTED
-PNG_EXPORT(246, png_uint_32, png_get_eXIf, (png_const_structrp png_ptr,
-    png_inforp info_ptr, png_bytep *exif));
-PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
-    png_inforp info_ptr, const png_bytep exif));
-
-PNG_EXPORT(248, png_uint_32, png_get_eXIf_1, (png_const_structrp png_ptr,
-    png_const_inforp info_ptr, png_uint_32 *num_exif, png_bytep *exif));
-PNG_EXPORT(249, void, png_set_eXIf_1, (png_const_structrp png_ptr,
-    png_inforp info_ptr, const png_uint_32 num_exif, const png_bytep exif));
-#endif
-
 #ifdef PNG_gAMA_SUPPORTED
 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
    png_const_inforp info_ptr, double *file_gamma))
@@ -2039,6 +2001,9 @@ PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
 #ifdef PNG_hIST_SUPPORTED
 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_uint_16p *hist));
+#endif
+
+#ifdef PNG_hIST_SUPPORTED
 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_const_uint_16p hist));
 #endif
@@ -2306,10 +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,
@@ -2317,7 +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,
@@ -2538,37 +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
@@ -2604,38 +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

@@ -2764,7 +2723,7 @@ typedef struct
 *
 * When the simplified API needs to convert between sRGB and linear colorspaces,
 * the actual sRGB transfer curve defined in the sRGB specification (see the
- * article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+ * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 * approximation used elsewhere in libpng.
 *
 * When an alpha channel is present it is expected to denote pixel coverage
@@ -2819,8 +2778,6 @@ typedef struct
 #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
 #endif

-#define PNG_FORMAT_FLAG_ASSOCIATED_ALPHA 0x40U /* alpha channel is associated */
-
 /* Commonly used formats have predefined macros.
 *
 * First the single byte (sRGB) formats:
@@ -2932,19 +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)\
@@ -3065,6 +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
@@ -3081,7 +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));
@@ -3091,9 +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.
@@ -3105,103 +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
@@ -3235,14 +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_IGNORE_ADLER32 8
-#ifdef PNG_POWERPC_VSX_API_SUPPORTED
-#  define PNG_POWERPC_VSX   10 /* HARDWARE: PowerPC VSX SIMD instructions supported */
-#endif
-#define PNG_OPTION_NEXT  12 /* 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 */
@@ -3266,7 +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(249);
+  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 1.6.34, September 29, 2017
+ * 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
@@ -507,9 +507,9 @@
 #  error "libpng requires a signed 32-bit (or more) type"
 #endif

-#if UINT_MAX > 4294967294U
+#if UINT_MAX > 4294967294
   typedef unsigned int png_uint_32;
-#elif ULONG_MAX > 4294967294U
+#elif ULONG_MAX > 4294967294
   typedef unsigned long int png_uint_32;
 #else
 #  error "libpng requires an unsigned 32-bit (or more) type"
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,8 +1,8 @@

 /* pngerror.c - stub functions for i/o and memory allocation
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 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 */
@@ -163,7 +163,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
         case PNG_NUMBER_FORMAT_02u:
            /* Expects at least 2 digits. */
            mincount = 2;
-            /* FALLTHROUGH */
+            /* FALL THROUGH */

         case PNG_NUMBER_FORMAT_u:
            *--end = digits[number % 10];
@@ -173,7 +173,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
         case PNG_NUMBER_FORMAT_02x:
            /* This format expects at least two digits */
            mincount = 2;
-            /* FALLTHROUGH */
+            /* FALL THROUGH */

         case PNG_NUMBER_FORMAT_x:
            *--end = digits[number & 0xf];
@@ -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)
@@ -573,7 +573,7 @@ png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
 {
 #  define fixed_message "fixed point overflow in "
 #  define fixed_message_ln ((sizeof fixed_message)-1)
-   unsigned int  iin;
+   int  iin;
   char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
   memcpy(msg, fixed_message, fixed_message_ln);
   iin = 0;
@@ -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 1.6.32 [August 24, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 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.)
 *
@@ -338,7 +338,7 @@ ppi_from_ppm(png_uint_32 ppm)
   png_fixed_point result;
   if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
       5000) != 0)
-      return (png_uint_32)result;
+      return result;

   /* Overflow. */
   return 0;
@@ -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);
   }

@@ -773,35 +773,6 @@ png_get_sPLT(png_const_structrp png_ptr, png_inforp info_ptr,
 }
 #endif

-#ifdef PNG_eXIf_SUPPORTED
-png_uint_32 PNGAPI
-png_get_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
-    png_bytep *exif)
-{
-  png_warning(png_ptr, "png_get_eXIf does not work; use png_get_eXIf_1");
-  PNG_UNUSED(info_ptr)
-  PNG_UNUSED(exif)
-  return 0;
-}
-
-png_uint_32 PNGAPI
-png_get_eXIf_1(png_const_structrp png_ptr, png_const_inforp info_ptr,
-    png_uint_32 *num_exif, png_bytep *exif)
-{
-   png_debug1(1, "in %s retrieval function", "eXIf");
-
-   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_eXIf) != 0 && exif != NULL)
-   {
-      *num_exif = info_ptr->num_exif;
-      *exif = info_ptr->exif;
-      return (PNG_INFO_eXIf);
-   }
-
-   return (0);
-}
-#endif
-
 #ifdef PNG_hIST_SUPPORTED
 png_uint_32 PNGAPI
 png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
@@ -930,7 +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);
   }

@@ -1171,19 +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/pnginfo.h
+++ b/pnginfo.h
@@ -185,14 +185,6 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
   png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 #endif

-#ifdef PNG_eXIf_SUPPORTED
-   int num_exif;  /* Added at libpng-1.6.31 */
-   png_bytep exif;
-# ifdef PNG_READ_eXIf_SUPPORTED
-   png_bytep eXIf_buf;  /* Added at libpng-1.6.32 */
-# endif
-#endif
-
 #ifdef PNG_hIST_SUPPORTED
   /* The hIST chunk contains the relative frequency or importance of the
    * various palette entries, so that a viewer can intelligently select a
--- a/pngmem.c
+++ b/pngmem.c
@@ -1,8 +1,8 @@

 /* pngmem.c - stub functions for memory allocation
 *
- * Last changed in libpng 1.6.26 [October 20, 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
@@ -107,9 +107,9 @@ 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 = (png_alloc_size_t)nelements; /* known to be > 0 */
+   png_alloc_size_t req = nelements; /* known to be > 0 */

   if (req <= PNG_SIZE_MAX/element_size)
      return png_malloc_base(png_ptr, req * element_size);
@@ -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 1.6.32 [August 24, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 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;
@@ -189,7 +189,6 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
      png_crc_read(png_ptr, chunk_tag, 4);
      png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
      png_check_chunk_name(png_ptr, png_ptr->chunk_name);
-      png_check_chunk_length(png_ptr, png_ptr->push_length);
      png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
   }

@@ -211,14 +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");
@@ -411,7 +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;
@@ -502,10 +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;
   }
@@ -522,7 +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;
@@ -625,7 +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)
@@ -685,12 +679,7 @@ png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
            png_warning(png_ptr, "Truncated compressed data in IDAT");

         else
-         {
-            if (ret == Z_DATA_ERROR)
-               png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
-            else
-               png_error(png_ptr, "Decompression error in IDAT");
-         }
+            png_error(png_ptr, "Decompression error in IDAT");

         /* Skip the check on unprocessed input */
         return;
@@ -788,7 +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)
      {
@@ -1050,7 +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 1.6.32 [August 24, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 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.)
 *
@@ -35,9 +35,7 @@
 * Windows/Visual Studio) there is no effect; the OS specific tests below are
 * still required (as of 2011-05-02.)
 */
-#ifndef _POSIX_SOURCE
-# define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
-#endif
+#define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */

 #ifndef PNG_VERSION_INFO_ONLY
 /* Standard library headers not required by png.h: */
@@ -184,84 +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
-
-#ifndef PNG_POWERPC_VSX_OPT
-#  if defined(__PPC64__) && defined(__ALTIVEC__) && defined(__VSX__)
-#     define PNG_POWERPC_VSX_OPT 2
-#  else
-#     define PNG_POWERPC_VSX_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
-#           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 */
-
-#if PNG_POWERPC_VSX_OPT > 0
-#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
-#  define PNG_POWERPC_VSX_IMPLEMENTATION 1
-#endif
-
-
 /* 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.
@@ -454,21 +374,6 @@
 #  define png_fixed_error(s1,s2) png_err(s1)
 #endif

-/* Some fixed point APIs are still required even if not exported because
- * they get used by the corresponding floating point APIs.  This magic
- * deals with this:
- */
-#ifdef PNG_FIXED_POINT_SUPPORTED
-#  define PNGFAPI PNGAPI
-#else
-#  define PNGFAPI /* PRIVATE */
-#endif
-
-#ifndef PNG_VERSION_INFO_ONLY
-/* Other defines specific to compilers can go here.  Try to keep
- * them inside an appropriate ifdef/endif pair for portability.
- */
-
 /* C allows up-casts from (void*) to any pointer and (const void*) to any
 * pointer to a const object.  C++ regards this as a type error and requires an
 * explicit, static, cast and provides the static_cast<> rune to ensure that
@@ -483,20 +388,25 @@
   static_cast<type>(static_cast<const void*>(value))
 #else
 #  define png_voidcast(type, value) (value)
-#  ifdef _WIN64
-#     ifdef __GNUC__
-         typedef unsigned long long png_ptruint;
-#     else
-         typedef unsigned __int64 png_ptruint;
-#     endif
-#  else
-      typedef unsigned long png_ptruint;
-#  endif
-#  define png_constcast(type, value) ((type)(png_ptruint)(const void*)(value))
+#  define png_constcast(type, value) ((type)(value))
 #  define png_aligncast(type, value) ((void*)(value))
 #  define png_aligncastconst(type, value) ((const void*)(value))
 #endif /* __cplusplus */

+/* Some fixed point APIs are still required even if not exported because
+ * they get used by the corresponding floating point APIs.  This magic
+ * deals with this:
+ */
+#ifdef PNG_FIXED_POINT_SUPPORTED
+#  define PNGFAPI PNGAPI
+#else
+#  define PNGFAPI /* PRIVATE */
+#endif
+
+#ifndef PNG_VERSION_INFO_ONLY
+/* Other defines specific to compilers can go here.  Try to keep
+ * them inside an appropriate ifdef/endif pair for portability.
+ */
 #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
   /* png.c requires the following ANSI-C constants if the conversion of
@@ -510,10 +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
@@ -521,9 +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
@@ -594,8 +504,7 @@
 /* This implicitly assumes alignment is always to a power of 2. */
 #ifdef png_alignof
 #  define png_isaligned(ptr, type)\
-   (((type)((const char*)ptr-(const char*)0) & \
-   (type)(png_alignof(type)-1)) == 0)
+   ((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
 #else
 #  define png_isaligned(ptr, type) 0
 #endif
@@ -612,92 +521,92 @@
 * are defined in png.h because they need to be visible to applications
 * that call png_set_unknown_chunk().
 */
-/* #define PNG_HAVE_IHDR            0x01U (defined in png.h) */
-/* #define PNG_HAVE_PLTE            0x02U (defined in png.h) */
-#define PNG_HAVE_IDAT               0x04U
-/* #define PNG_AFTER_IDAT           0x08U (defined in png.h) */
-#define PNG_HAVE_IEND               0x10U
-                   /*               0x20U (unused) */
-                   /*               0x40U (unused) */
-                   /*               0x80U (unused) */
-#define PNG_HAVE_CHUNK_HEADER      0x100U
-#define PNG_WROTE_tIME             0x200U
-#define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
-#define PNG_BACKGROUND_IS_GRAY     0x800U
-#define PNG_HAVE_PNG_SIGNATURE    0x1000U
-#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
-                   /*             0x4000U (unused) */
-#define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
+/* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
+/* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
+#define PNG_HAVE_IDAT               0x04
+/* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
+#define PNG_HAVE_IEND               0x10
+                   /*               0x20 (unused) */
+                   /*               0x40 (unused) */
+                   /*               0x80 (unused) */
+#define PNG_HAVE_CHUNK_HEADER      0x100
+#define PNG_WROTE_tIME             0x200
+#define PNG_WROTE_INFO_BEFORE_PLTE 0x400
+#define PNG_BACKGROUND_IS_GRAY     0x800
+#define PNG_HAVE_PNG_SIGNATURE    0x1000
+#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
+                   /*             0x4000 (unused) */
+#define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */

 /* Flags for the transformations the PNG library does on the image data */
-#define PNG_BGR                 0x0001U
-#define PNG_INTERLACE           0x0002U
-#define PNG_PACK                0x0004U
-#define PNG_SHIFT               0x0008U
-#define PNG_SWAP_BYTES          0x0010U
-#define PNG_INVERT_MONO         0x0020U
-#define PNG_QUANTIZE            0x0040U
-#define PNG_COMPOSE             0x0080U    /* Was PNG_BACKGROUND */
-#define PNG_BACKGROUND_EXPAND   0x0100U
-#define PNG_EXPAND_16           0x0200U    /* Added to libpng 1.5.2 */
-#define PNG_16_TO_8             0x0400U    /* Becomes 'chop' in 1.5.4 */
-#define PNG_RGBA                0x0800U
-#define PNG_EXPAND              0x1000U
-#define PNG_GAMMA               0x2000U
-#define PNG_GRAY_TO_RGB         0x4000U
-#define PNG_FILLER              0x8000U
-#define PNG_PACKSWAP           0x10000U
-#define PNG_SWAP_ALPHA         0x20000U
-#define PNG_STRIP_ALPHA        0x40000U
-#define PNG_INVERT_ALPHA       0x80000U
-#define PNG_USER_TRANSFORM    0x100000U
-#define PNG_RGB_TO_GRAY_ERR   0x200000U
-#define PNG_RGB_TO_GRAY_WARN  0x400000U
-#define PNG_RGB_TO_GRAY       0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
-#define PNG_ENCODE_ALPHA      0x800000U /* Added to libpng-1.5.4 */
-#define PNG_ADD_ALPHA        0x1000000U /* Added to libpng-1.2.7 */
-#define PNG_EXPAND_tRNS      0x2000000U /* Added to libpng-1.2.9 */
-#define PNG_SCALE_16_TO_8    0x4000000U /* Added to libpng-1.5.4 */
-                       /*    0x8000000U unused */
-                       /*   0x10000000U unused */
-                       /*   0x20000000U unused */
-                       /*   0x40000000U unused */
+#define PNG_BGR                 0x0001
+#define PNG_INTERLACE           0x0002
+#define PNG_PACK                0x0004
+#define PNG_SHIFT               0x0008
+#define PNG_SWAP_BYTES          0x0010
+#define PNG_INVERT_MONO         0x0020
+#define PNG_QUANTIZE            0x0040
+#define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
+#define PNG_BACKGROUND_EXPAND   0x0100
+#define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
+#define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
+#define PNG_RGBA                0x0800
+#define PNG_EXPAND              0x1000
+#define PNG_GAMMA               0x2000
+#define PNG_GRAY_TO_RGB         0x4000
+#define PNG_FILLER              0x8000
+#define PNG_PACKSWAP           0x10000
+#define PNG_SWAP_ALPHA         0x20000
+#define PNG_STRIP_ALPHA        0x40000
+#define PNG_INVERT_ALPHA       0x80000
+#define PNG_USER_TRANSFORM    0x100000
+#define PNG_RGB_TO_GRAY_ERR   0x200000
+#define PNG_RGB_TO_GRAY_WARN  0x400000
+#define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
+#define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
+#define PNG_ADD_ALPHA        0x1000000 /* Added to libpng-1.2.7 */
+#define PNG_EXPAND_tRNS      0x2000000 /* Added to libpng-1.2.9 */
+#define PNG_SCALE_16_TO_8    0x4000000 /* Added to libpng-1.5.4 */
+                       /*    0x8000000 unused */
+                       /*   0x10000000 unused */
+                       /*   0x20000000 unused */
+                       /*   0x40000000 unused */
 /* Flags for png_create_struct */
-#define PNG_STRUCT_PNG   0x0001U
-#define PNG_STRUCT_INFO  0x0002U
+#define PNG_STRUCT_PNG   0x0001
+#define PNG_STRUCT_INFO  0x0002

 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
-#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001U
-#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002U /* Added to libpng-1.6.0 */
-                                  /*      0x0004U    unused */
-#define PNG_FLAG_ZSTREAM_ENDED            0x0008U /* Added to libpng-1.6.0 */
-                                  /*      0x0010U    unused */
-                                  /*      0x0020U    unused */
-#define PNG_FLAG_ROW_INIT                 0x0040U
-#define PNG_FLAG_FILLER_AFTER             0x0080U
-#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100U
-#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200U
-#define PNG_FLAG_CRC_CRITICAL_USE         0x0400U
-#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800U
-#define PNG_FLAG_ASSUME_sRGB              0x1000U /* Added to libpng-1.5.4 */
-#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000U /* Added to libpng-1.5.4 */
-#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000U /* Added to libpng-1.5.4 */
-/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000U */
-/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000U */
-#define PNG_FLAG_LIBRARY_MISMATCH        0x20000U
-#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000U
-#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000U
-#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000U /* Added to libpng-1.4.0 */
-#define PNG_FLAG_APP_WARNINGS_WARN      0x200000U /* Added to libpng-1.6.0 */
-#define PNG_FLAG_APP_ERRORS_WARN        0x400000U /* Added to libpng-1.6.0 */
-                                  /*    0x800000U    unused */
-                                  /*   0x1000000U    unused */
-                                  /*   0x2000000U    unused */
-                                  /*   0x4000000U    unused */
-                                  /*   0x8000000U    unused */
-                                  /*  0x10000000U    unused */
-                                  /*  0x20000000U    unused */
-                                  /*  0x40000000U    unused */
+#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
+#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
+                                  /*      0x0004    unused */
+#define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
+                                  /*      0x0010    unused */
+                                  /*      0x0020    unused */
+#define PNG_FLAG_ROW_INIT                 0x0040
+#define PNG_FLAG_FILLER_AFTER             0x0080
+#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
+#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
+#define PNG_FLAG_CRC_CRITICAL_USE         0x0400
+#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
+#define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
+/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
+/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
+#define PNG_FLAG_LIBRARY_MISMATCH        0x20000
+#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
+#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
+#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
+#define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
+                                  /*    0x800000    unused */
+                                  /*   0x1000000    unused */
+                                  /*   0x2000000    unused */
+                                  /*   0x4000000    unused */
+                                  /*   0x8000000    unused */
+                                  /*  0x10000000    unused */
+                                  /*  0x20000000    unused */
+                                  /*  0x40000000    unused */

 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                     PNG_FLAG_CRC_ANCILLARY_NOWARN)
@@ -731,24 +640,6 @@
    ((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
    (( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )

-/* This returns the number of trailing bits in the last byte of a row, 0 if the
- * last byte is completely full of pixels.  It is, in principle, (pixel_bits x
- * width) % 8, but that would overflow for large 'width'.  The second macro is
- * the same except that it returns the number of unused bits in the last byte;
- * (8-TRAILBITS), but 0 when TRAILBITS is 0.
- *
- * NOTE: these macros are intended to be self-evidently correct and never
- * overflow on the assumption that pixel_bits is in the range 0..255.  The
- * arguments are evaluated only once and they can be signed (e.g. as a result of
- * the integral promotions).  The result of the expression always has type
- * (png_uint_32), however the compiler always knows it is in the range 0..7.
- */
-#define PNG_TRAILBITS(pixel_bits, width) \
-    (((pixel_bits) * ((width) % (png_uint_32)8)) % 8)
-
-#define PNG_PADBITS(pixel_bits, width) \
-    ((8 - PNG_TRAILBITS(pixel_bits, width)) % 8)
-
 /* PNG_OUT_OF_RANGE returns true if value is outside the range
 * ideal-delta..ideal+delta.  Each argument is evaluated twice.
 * "ideal" and "delta" should be constants, normally simple
@@ -842,7 +733,6 @@
 #define png_PLTE PNG_U32( 80,  76,  84,  69)
 #define png_bKGD PNG_U32( 98,  75,  71,  68)
 #define png_cHRM PNG_U32( 99,  72,  82,  77)
-#define png_eXIf PNG_U32(101,  88,  73, 102) /* registered July 2017 */
 #define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
 #define png_gAMA PNG_U32(103,  65,  77,  65)
 #define png_gIFg PNG_U32(103,  73,  70, 103)
@@ -1135,7 +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
@@ -1143,11 +1033,6 @@ PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
    int intent),PNG_EMPTY);
 #endif

-#ifdef PNG_WRITE_eXIf_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_write_eXIf,(png_structrp png_ptr,
-    png_bytep exif, int num_exif),PNG_EMPTY);
-#endif
-
 #ifdef PNG_WRITE_iCCP_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
   png_const_charp name, png_const_bytep profile), PNG_EMPTY);
@@ -1289,7 +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
@@ -1304,56 +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
-
-#if PNG_POWERPC_VSX_OPT > 0
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_vsx,(png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_vsx,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_vsx,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_vsx,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_vsx,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_vsx,(png_row_infop
-    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_vsx,(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,
@@ -1381,7 +1215,7 @@ PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
 /* Initialize the row buffers, etc. */
 PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);

-#if ZLIB_VERNUM >= 0x1240
+#if PNG_ZLIB_VERNUM >= 0x1240
 PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
      PNG_EMPTY);
 #  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
@@ -1447,11 +1281,6 @@ PNG_INTERNAL_FUNCTION(void,png_handle_cHRM,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif

-#ifdef PNG_READ_eXIf_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_handle_eXIf,(png_structrp png_ptr,
-    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
-#endif
-
 #ifdef PNG_READ_gAMA_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
@@ -1527,11 +1356,8 @@ PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif

-PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_const_structrp png_ptr,
-    const png_uint_32 chunk_name),PNG_EMPTY);
-
-PNG_INTERNAL_FUNCTION(void,png_check_chunk_length,(png_const_structrp png_ptr,
-    const png_uint_32 chunk_length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_structrp png_ptr,
+    png_uint_32 chunk_name),PNG_EMPTY);

 PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
@@ -1587,7 +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,
@@ -1626,13 +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 */
@@ -1666,11 +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,
@@ -2089,22 +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
-
-#  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);

--- a/Show More
+++ b/Show More