[master] Imported from libpng-1.6.28.tar

[master] Imported from libpng-1.6.27.tar
[master] Imported from libpng-1.6.26.tar
2025-07-10 18:04:09 +02:00 · 2017-01-05 11:50:11 -05:00 · 2016-12-29 08:10:06 -06:00 · 2016-10-19 19:11:48 -05:00 · 2016-08-31 22:30:55 -05:00 · 2016-08-03 21:42:00 -05:00
164 changed files with 1875 additions and 4715 deletions
--- a/39
+++ b/39
@@ -1,41 +1,34 @@
-Libpng 1.6.35beta01 - March 6, 2018
+Libpng 1.6.28 - January 5, 2017

-This is not intended to be a public release. It will be replaced
-within a few weeks by a public version or by another test version.
+This is a public release of libpng, intended for use in production codes.

 Files available for download:

 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   1.6.35beta01.tar.xz (LZMA-compressed, recommended)
-   1.6.35beta01.tar.gz
+   libpng-1.6.28.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.28.tar.gz

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

-   lp1635b01.7z  (LZMA-compressed, recommended)
-   lp1635b01.zip
+   lpng1628.7z  (LZMA-compressed, recommended)
+   lpng1628.zip

 Other information:

-   1.6.35beta01-README.txt
-   1.6.35beta01-LICENSE.txt
+   libpng-1.6.28-README.txt
+   libpng-1.6.28-LICENSE.txt
+   libpng-1.6.28-*.asc (armored detached GPG signatures)

-Changes since the last public release (1.6.34):
-
-Version 1.6.35beta01 [March 6, 2018]
-  Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
-    failures. Placed the remainder in contrib/pngsuite/interlaced/i*.png.
-  Added calls to png_set_*() transforms commonly used by browsers to
-    the fuzzer.
-  Removed some unnecessary brackets in pngrtran.c
-  Fixed miscellaneous typos (Patch by github user "luzpaz")
-  Change "ASM C" to "C ASM" in CMakeLists.txt
-  Fixed incorrect handling of bKGD chunk in sub-8-bit files (Cosmin)
-  Added hardware optimization directories to zip and 7z distributions.
-  Fixed incorrect bitmask for options.
-  Fixed many spelling typos.
+Changes since the last public release (1.6.27):
+  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.

 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
--- a/287
+++ b/287
@@ -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.
@@ -1454,7 +1454,7 @@ Version 1.2.6beta4 [July 28, 2004]
    sequential read support.
  Added some "#if PNG_WRITE_SUPPORTED" blocks.
  Added #ifdef to remove some redundancy in png_malloc_default().
-  Use png_malloc instead of png_zalloc to allocate the palette.
+  Use png_malloc instead of png_zalloc to allocate the pallete.

 Version 1.0.16rc1 and 1.2.6rc1 [August 4, 2004]
  Fixed buffer overflow vulnerability (CVE-2004-0597) in png_handle_tRNS().
@@ -3259,7 +3259,7 @@ Version 1.5.2beta01 [February 13, 2011]
  Revised PNG_EXPORTA macro to not use an empty parameter, to accommodate the
    old VisualC++ preprocessor.
  Turned on interlace handling in png_read_png().
-  Fixed gcc pedantic warnings.
+  Fixed gcc pendantic warnings.
  Handle longjmp in Cygwin.
  Fixed png_get_current_row_number() in the interlaced case.
  Cleaned up ALPHA flags and transformations.
@@ -3359,7 +3359,7 @@ Version 1.5.3beta05 [May 6, 2011]
  Pass "" instead of '\0' to png_default_error() in png_err().  This mistake
    was introduced in libpng-1.2.20beta01.  This fixes CVE-2011-2691.
  Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte
-    optimization configurable.
+    optimization configureable.
  IDAT compression failed if preceded by a compressed text chunk (bug
    introduced in libpng-1.5.3beta01-02).  This was because the attempt to
    reset the zlib stream in png_write_IDAT happened after the first IDAT
@@ -3643,7 +3643,7 @@ Version 1.5.6beta05 [October 12, 2011]
  Fixed bug in png_write_chunk_header() debug print, introduced in 1.5.6beta01.

 Version 1.5.6beta06 [October 17, 2011]
-  Removed two redundant tests for uninitialized row.
+  Removed two redundant tests for unitialized row.
  Fixed a relatively harmless memory overwrite in compressed text writing
    with a 1 byte zlib buffer.
  Add ability to call png_read_update_info multiple times to pngvalid.c.
@@ -3689,7 +3689,7 @@ Version 1.5.7beta01 [November 4, 2011]
    crash.  The pngmem.c implementation of png_malloc() included a cast
    to png_size_t which would fail on large allocations on 16-bit systems.
  Fix for the preprocessor of the Intel C compiler. The preprocessor
-    splits adjacent @ signs with a space; this changes the concatenation
+    splits adjacent @ signs with a space; this changes the concatentation
    token from @-@-@ to PNG_JOIN; that should work with all compiler
    preprocessors.
  Paeth filter speed improvements from work by Siarhei Siamashka. This
@@ -3735,7 +3735,7 @@ Version 1.5.7beta03 [November 17, 2011]
    gray (on palette) itself.
  Fixes for C++ compilation using g++ When libpng source is compiled
    using g++. The compiler imposes C++ rules on the C source; thus it
-    is desirable to make the source work with either C or C++ rules
+    is desireable to make the source work with either C or C++ rules
    without throwing away useful error information.  This change adds
    png_voidcast to allow C semantic (void*) cases or the corresponding
    C++ static_cast operation, as appropriate.
@@ -4061,7 +4061,7 @@ Version 1.6.0beta17 [March 10, 2012]
    possible to call png_inflate() incrementally.  A warning is no longer
    issued if the language tag or translated keyword in the iTXt chunk
    has zero length.
-  If benign errors are disabled use maximum window on ancillary inflate.
+  If benign errors are disabled use maximum window on ancilliary inflate.
    This works round a bug introduced in 1.5.4 where compressed ancillary
    chunks could end up with a too-small windowBits value in the deflate
    header.
@@ -4176,7 +4176,7 @@ Version 1.6.0beta27 [August 11, 2012]
    declared even though the functions are never actually defined.  This
    change provides a dummy definition so that the declarations work, yet any
    implementation will fail to compile because of an incomplete type.
-  Re-eliminated the use of strcpy() in pngtest.c.  An unnecessary use of
+  Re-eliminated the use of strcpy() in pngtest.c.  An unncessary use of
    strcpy() was accidentally re-introduced in libpng16; this change replaces
    it with strncpy().
  Eliminated use of png_sizeof(); use sizeof() instead.
@@ -4309,7 +4309,7 @@ Version 1.6.0beta31 [November 1, 2012]
    resulting in VS2010 having to update the files.
  Removed non-working ICC profile support code that was mostly added to
    libpng-1.6.0beta29 and beta30. There was too much code for too little
-    gain; implementing full ICC color correction may be desirable but is left
+    gain; implementing full ICC color correction may be desireable but is left
    up to applications.

 Version 1.6.0beta32 [November 25, 2012]
@@ -4592,7 +4592,7 @@ Version 1.6.3beta07 [June 8, 2013]
    the optimizations ('check' vs 'api') are exposed in the public header files
    except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
    decision about whether or not to use the optimizations.
-  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS usage.
+  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
    Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
    on __ARM_NEON__ from configure time to compile time.  This breaks symbol
    prefixing because the definition of the special png_init_filter_functions
@@ -5635,7 +5635,7 @@ Version 1.6.24beta02 [June 23, 2016]
    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 significant change (moving
+    structure padding is fixable, but it would be a signficant change (moving
    structure members around).

 Version 1.6.24beta03 [July 4, 2016]
@@ -5761,9 +5761,7 @@ Version 1.6.27beta01 [November 2, 2016]
    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.
+  Control ADLER32 checking with new PNG_IGNORE_ADLER32 option.
  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
@@ -5781,7 +5779,7 @@ Version 1.6.28rc01 [January 3, 2017]
  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 accommodate
+  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]
@@ -5796,263 +5794,6 @@ Version 1.6.28rc03 [January 4, 2017]
 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 compatibility.
-
-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 them caused test failures.
-
-Version 1.6.35beta01 [March 6, 2018]
-  Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
-    failures. Placed the remainder in contrib/pngsuite/interlaced/i*.png.
-  Added calls to png_set_*() transforms commonly used by browsers to
-    the fuzzer.
-  Removed some unnecessary brackets in pngrtran.c
-  Fixed miscellaneous typos (Patch by github user "luzpaz").
-  Change "ASM C" to "C ASM" in CMakeLists.txt
-  Fixed incorrect handling of bKGD chunk in sub-8-bit files (Cosmin)
-  Added hardware optimization directories to zip and 7z distributions.
-  Fixed incorrect bitmask for options.
-  Fixed many spelling typos.
-
 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
@@ -1,6 +1,6 @@
 # CMakeLists.txt

-# Copyright (C) 2007,2009-2017 Glenn Randers-Pehrson
+# Copyright (C) 2007,2009-2016 Glenn Randers-Pehrson
 # Written by Christian Ehrlicher, 2007
 # Revised by Roger Lowman, 2009-2010
 # Revised by Clifford Yapp, 2011-2012
@@ -11,8 +11,8 @@
 # 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)
+cmake_minimum_required(VERSION 2.8.3)
+cmake_policy(VERSION 2.8.3)

 # Set MacOSX @rpath usage globally.
 if (POLICY CMP0020)
@@ -31,20 +31,18 @@ endif(POLICY CMP0054)

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

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

 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 35)
+set(PNGLIB_RELEASE 28)
 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,
+#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)

@@ -76,16 +74,12 @@ 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")
+if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "^arm" OR
+  ${CMAKE_SYSTEM_PROCESSOR} MATCHES "^aarch64")
  set(PNG_ARM_NEON_POSSIBLE_VALUES check on off)
  set(PNG_ARM_NEON "check" CACHE STRING "Enable ARM NEON optimizations:
     check: (default) use internal checking code;
@@ -102,7 +96,7 @@ if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
      arm/arm_init.c
      arm/filter_neon.S
      arm/filter_neon_intrinsics.c)
-
+      
    if(${PNG_ARM_NEON} STREQUAL "on")
      add_definitions(-DPNG_ARM_NEON_OPT=2)
    elseif(${PNG_ARM_NEON} STREQUAL "check")
@@ -113,79 +107,6 @@ if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
  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})

@@ -262,7 +183,7 @@ find_program(AWK NAMES gawk awk)

 include_directories(${CMAKE_CURRENT_BINARY_DIR})

-if(NOT AWK OR ANDROID)
+if(NOT AWK)
  # No awk available to generate sources; use pre-built pnglibconf.h
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
                 ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
@@ -424,7 +345,7 @@ else()
                    WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")

  # A single target handles generation of all generated files.  If
-  # they are depended upon separately by multiple targets, this
+  # 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
@@ -441,7 +362,7 @@ else()
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out")
-endif(NOT AWK OR ANDROID)
+endif(NOT AWK)

 # OUR SOURCES
 set(libpng_public_hdrs
@@ -455,7 +376,7 @@ set(libpng_private_hdrs
  pnginfo.h
  pngstruct.h
 )
-if(AWK AND NOT ANDROID)
+if(AWK)
  list(APPEND libpng_private_hdrs "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h")
 endif()
 set(libpng_sources
@@ -477,9 +398,6 @@ set(libpng_sources
  pngwtran.c
  pngwutil.c
  ${libpng_arm_sources}
-  ${libpng_intel_sources}
-  ${libpng_mips_sources}
-  ${libpng_powerpc_sources}
 )
 set(pngtest_sources
  pngtest.c
@@ -755,58 +673,31 @@ if(PNG_SHARED)
  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()
+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()

 # Create source generation scripts.
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genchk.cmake.in
@@ -834,17 +725,17 @@ if(NOT WIN32 OR CYGWIN OR MINGW)
  set(LIBS        "-lz -lm")
  configure_file(${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.${PNGLIB_RELEASE}.1.6.35beta01
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.28
    VERSION 16.${PNGLIB_RELEASE}.0
    SOVERSION 16
    CLEAN_DIRECT_OUTPUT 1)
@@ -871,20 +762,26 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
  if(PNG_SHARED)
    # Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
    if(CYGWIN OR MINGW)
-      CREATE_SYMLINK(libpng${CMAKE_IMPORT_LIBRARY_SUFFIX} TARGET png)
-      install(FILES $<TARGET_LINKER_FILE_DIR:png>/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX} DESTINATION ${CMAKE_INSTALL_LIBDIR})
+       get_target_property(BUILD_TARGET_LOCATION png LOCATION_${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 ${CMAKE_INSTALL_LIBDIR})
+      get_target_property(BUILD_TARGET_LOCATION png LOCATION_${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 ${CMAKE_INSTALL_LIBDIR})
+      get_target_property(BUILD_TARGET_LOCATION png_static LOCATION_${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()
@@ -914,7 +811,7 @@ 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 +820,7 @@ 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 +840,4 @@ endif()
 # to create msvc import lib for mingw compiled shared lib
 # pexports libpng.dll > libpng.def
 # lib /def:libpng.def /machine:x86
+
--- a/71
+++ b/71
@@ -16,11 +16,10 @@ Contents
      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
+     XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+      XV. Setjmp/longjmp issues
+     XVI. Common linking failures
+    XVII. Other sources of information about libpng

 I. Simple installation

@@ -79,8 +78,8 @@ 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 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
@@ -282,57 +281,7 @@ 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 capabilities, 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
@@ -423,7 +372,7 @@ $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
@@ -441,7 +390,7 @@ 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
+XVI. Common linking failures

 If your application fails to find libpng or zlib entries while linking:

@@ -453,7 +402,7 @@ If your application fails to find libpng or zlib entries while linking:
  If you are using the vstudio project, observe the WARNING in
  project/vstudio/README.txt.

-XVIII. Other sources of information about libpng:
+XVII. 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
--- a/8
+++ b/8
@@ -10,8 +10,8 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.0.7, July 1, 2000 through 1.6.35beta01, March 6, 2018 are
-Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson, are
+libpng versions 1.0.7, July 1, 2000 through 1.6.28, January 5, 2017 are
+Copyright (c) 2000-2002, 2004, 2006-2017 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:
@@ -23,8 +23,6 @@ added to the list of Contributing Authors:
   Gilles Vollant
   James Yu
   Mandar Sahastrabuddhe
-   Google Inc.
-   Vadim Barkov

 and with the following additions to the disclaimer:

@@ -130,4 +128,4 @@ any encryption software.  See the EAR, paragraphs 734.3(b)(3) and

 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-March 6, 2018
+January 5, 2017
--- a/Makefile.am
+++ b/Makefile.am
@@ -60,7 +60,6 @@ pngcp_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 # 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\
@@ -103,16 +102,6 @@ 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 \
--- a/18
+++ b/18
@@ -1,4 +1,4 @@
-README for libpng version 1.6.35beta01 - March 6, 2018 (shared library 16.0)
+README for libpng version 1.6.28 - January 5, 2017 (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
@@ -179,16 +179,14 @@ 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
+       intel            =>  Optimized code for INTEL-SSE2 platform
       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
@@ -196,8 +194,6 @@ Files in this distribution:
       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/1
+++ b/1
@@ -25,6 +25,5 @@ Use greater precision when changing to linear gamma for compositing against
 Investigate pre-incremented loop counters and other loop constructions.
 Add interpolated method of handling interlacing.
 Extend pngvalid.c to validate more of the libpng transformations.
-Refactor preprocessor conditionals to compile entire statements

 */
--- 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/autogen.sh
+++ b/autogen.sh
@@ -194,7 +194,7 @@ case "$mode" in
      if test -d .git
      then
         exec >&2
-         echo "ERROR: running autoreconf on an initialized system"
+         echo "ERROR: running autoreconf on an initialized sytem"
         echo "  This is not necessary; it is only necessary to remake the"
         echo "  autotools generated files if Makefile.am or configure.ac"
         echo "  change and make does the right thing with:"
--- a/configure.ac
+++ b/configure.ac
@@ -25,7 +25,7 @@ AC_PREREQ([2.68])

 dnl Version number stuff here:

-AC_INIT([libpng],[1.6.35beta01],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.28],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])

 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -46,10 +46,10 @@ 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=1.6.35beta01
+PNGLIB_VERSION=1.6.28
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=35
+PNGLIB_RELEASE=28

 dnl End of version number stuff

@@ -300,55 +300,6 @@ 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
 # ===
 #
@@ -440,89 +391,6 @@ AM_CONDITIONAL([PNG_MIPS_MSA],
      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
@@ -33,7 +33,7 @@ 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 support
+# pngcp can work without explicit known chunk reading suppport
 option UNKNOWN_CHUNKS on
 option SET_UNKNOWN_CHUNKS on
 option HANDLE_AS_UNKNOWN on
--- a/contrib/examples/iccfrompng.c
+++ b/contrib/examples/iccfrompng.c
@@ -10,7 +10,7 @@
 * without processing the image.  Notice that some header information may occur
 * after the image data. Textual data and comments are an example; the approach
 * in this file won't work reliably for such data because it only looks for the
- * information in the section of the file that precedes the image data.
+ * information in the section of the file that preceeds the image data.
 *
 * Compile and link against libpng and zlib, plus anything else required on the
 * system you use.
--- 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
@@ -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
@@ -55,7 +55,6 @@

   Changelog:
     2015-11-12 - Check return value of png_get_bKGD() (Glenn R-P)
-     2017-04-22 - Guard against integer overflow (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
@@ -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
@@ -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/intel/INSTALL
+++ b/contrib/intel/INSTALL
@@ -0,0 +1,158 @@
+Enabling SSE support
+
+Copyright (c) 2016 Google, Inc.
+Written by Mike Klein, Matt Sarett
+
+This INSTALL file written by Glenn Randers-Pehrson, 2016.
+
+If you have moved intel_init.c and filter_sse2_intrinsics.c to a different
+directory, be sure to update the '#include "../../pngpriv.h"' line in both
+files if necessary to point to the correct relative location of pngpriv.h
+with respect to the new location of those files.
+
+To enable SSE support in libpng, follow the instructions in I, II, or III,
+below:
+
+I. Using patched "configure" scripts:
+
+First, apply intel_sse.patch in your build directory.
+
+   patch -i contrib/intel/intel_sse.patch -p1
+
+Then, if you are not building in a new GIT clone, e.g., in a tar
+distribution, remove any existing pre-built configure scripts:
+
+   ./configure --enable-maintainer-mode
+   make maintainer-clean
+   ./autogen.sh --maintainer --clean
+
+Finally, configure libpng with -DPNG_INTEL_SSE in CPPFLAGS:
+
+   ./autogen.sh --maintainer
+   CPPFLAGS="-DPNG_INTEL_SSE" ./configure [options]
+   make CPPFLAGS="-DPNG_INTEL_SSE" [options]
+   make
+
+II. Using a custom makefile:
+
+If you are using a custom makefile makefile, you will have to update it
+manually to include contrib/intel/*.o in the dependencies, and to define
+PNG_INTEL_SSE.
+
+III. Using manually updated "configure" scripts:
+
+If you prefer, manually edit pngpriv.h, configure.ac, and Makefile.am,
+following the instructions below, then follow the instructions in
+section II of INSTALL in the main libpng directory, then configure libpng
+with -DPNG_INTEL_SSE in CPPFLAGS.
+
+1. Add the following code to configure.ac under HOST SPECIFIC OPTIONS
+directly beneath the section for ARM:
+
+-----------------cut----------------
+# INTEL
+# =====
+#
+# INTEL SSE (SIMD) support.
+
+AC_ARG_ENABLE([intel-sse],
+   AS_HELP_STRING([[[--enable-intel-sse]]],
+      [Enable Intel SSE optimizations: =no/off, yes/on:]
+      [no/off: disable the optimizations;]
+      [yes/on: enable the optimizations.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling:
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
+                   [Disable Intel SSE optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_intel_sse=no;;
+      yes|on)
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
+                   [Enable Intel SSE optimizations]);;
+      *)
+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
+   esac])
+
+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
+# or where Intel optimizations were explicitly requested (this allows a
+# fallback if a future host CPU does not match 'x86*')
+AM_CONDITIONAL([PNG_INTEL_SSE],
+   [test "$enable_intel_sse" != 'no' &&
+    case "$host_cpu" in
+      i?86|x86_64) :;;
+      *)    test "$enable_intel_sse" != '';;
+    esac])
+-----------------cut----------------
+
+2. Add the following code to Makefile.am under HOST SPECIFIC OPTIONS
+directly beneath the "if PNG_ARM_NEON ... endif" statement:
+
+-----------------cut----------------
+if PNG_INTEL_SSE
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
+    contrib/intel/filter_sse2_intrinsics.c
+endif
+-----------------cut----------------
+
+3. Add the following lines to pngpriv.h, following the PNG_ARM_NEON_OPT
+code:
+
+-----------------cut----------------
+#ifndef PNG_INTEL_SSE_OPT
+#   ifdef PNG_INTEL_SSE
+      /* Only check for SSE if the build configuration has been modified to
+       * enable SSE optimizations.  This means that these optimizations will
+       * be off by default.  See contrib/intel for more details.
+       */
+#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
+       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
+#         define PNG_INTEL_SSE_OPT 1
+#      endif
+#   endif
+#endif
+
+#if PNG_INTEL_SSE_OPT > 0
+#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
+#      if defined(__SSE4_1__) || defined(__AVX__)
+          /* We are not actually using AVX, but checking for AVX is the best
+             way we can detect SSE4.1 and SSSE3 on MSVC.
+          */
+#         define PNG_INTEL_SSE_IMPLEMENTATION 3
+#      elif defined(__SSSE3__)
+#         define PNG_INTEL_SSE_IMPLEMENTATION 2
+#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
+#         define PNG_INTEL_SSE_IMPLEMENTATION 1
+#      else
+#         define PNG_INTEL_SSE_IMPLEMENTATION 0
+#      endif
+#   endif
+
+#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
+#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
+#   endif
+#endif
+
+-----------------cut----------------
+
+4. Add the following lines to pngpriv.h, following the prototype for
+png_read_filter_row_paeth4_neon:
+
+-----------------cut----------------
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+
+-----------------cut----------------
--- a/contrib/intel/filter_sse2_intrinsics.c
+++ b/contrib/intel/filter_sse2_intrinsics.c
@@ -1,18 +1,19 @@

 /* filter_sse2_intrinsics.c - SSE2 optimized filter functions
 *
- * Copyright (c) 2016-2017 Glenn Randers-Pehrson
+ * Copyright (c) 2016 Google, Inc.
 * Written by Mike Klein and Matt Sarett
- * Derived from arm/filter_neon_intrinsics.c
+ * Derived from arm/filter_neon_intrinsics.c, which was
+ * Copyright (c) 2014,2016 Glenn Randers-Pehrson
 *
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.24 [August 4, 2016]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

-#include "../pngpriv.h"
+#include "../../pngpriv.h"

 #ifdef PNG_READ_SUPPORTED

@@ -40,7 +41,7 @@ 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_uint_16* p01 = p;
   const png_byte*    p2  = (const png_byte*)(p01+1);

   png_uint_32 v012 = (png_uint_32)(*p01)
@@ -53,15 +54,12 @@ static void store3(void* p, __m128i v) {
    * 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);
+   png_uint_16* p01 = p;
+   png_byte*    p2  = (png_byte*)(p01+1);
+   *p01 = v012;
+   *p2  = v012 >> 16;
 }

 void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
@@ -71,13 +69,10 @@ void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
    * 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;
-
+   png_debug(1, "in png_read_filter_row_sub3_sse2");
   __m128i a, d = _mm_setzero_si128();

-   png_debug(1, "in png_read_filter_row_sub3_sse2");
-
-   rb = row_info->rowbytes;
+   int rb = row_info->rowbytes;
   while (rb >= 4) {
      a = d; d = load4(row);
      d = _mm_add_epi8(d, a);
@@ -94,7 +89,6 @@ void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
      row += 3;
      rb  -= 3;
   }
-   PNG_UNUSED(prev)
 }

 void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
@@ -104,14 +98,11 @@ void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
    * 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;
-
+   png_debug(1, "in png_read_filter_row_sub4_sse2");
   __m128i a, d = _mm_setzero_si128();

-   png_debug(1, "in png_read_filter_row_sub4_sse2");
-
-   rb = row_info->rowbytes+4;
-   while (rb > 4) {
+   int rb = row_info->rowbytes;
+   while (rb > 0) {
      a = d; d = load4(row);
      d = _mm_add_epi8(d, a);
      store4(row, d);
@@ -119,7 +110,6 @@ void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
      row += 4;
      rb  -= 4;
   }
-   PNG_UNUSED(prev)
 }

 void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
@@ -130,23 +120,18 @@ void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
    * 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;
-
+   png_debug(1, "in png_read_filter_row_avg3_sse2");
   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;
+   int 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);
+      __m128i avg = _mm_avg_epu8(a,b);
      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
                                            _mm_set1_epi8(1)));
@@ -158,12 +143,11 @@ void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
      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);
+      __m128i avg = _mm_avg_epu8(a,b);
      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
                                            _mm_set1_epi8(1)));
@@ -185,21 +169,18 @@ void png_read_filter_row_avg4_sse2(png_row_infop row_info, png_bytep row,
    * 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;
+   png_debug(1, "in png_read_filter_row_avg4_sse2");
   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;
+   int rb = row_info->rowbytes;
+   while (rb > 0) {
             b = load4(prev);
      a = d; d = load4(row );

      /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
-      avg = _mm_avg_epu8(a,b);
+      __m128i avg = _mm_avg_epu8(a,b);
      /* ...but we can fix it up by subtracting off 1 if it rounded up. */
      avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
                                            _mm_set1_epi8(1)));
@@ -257,42 +238,38 @@ void png_read_filter_row_paeth3_sse2(png_row_infop row_info, png_bytep row,
    * Here we zero b and d, which become c and a respectively at the start of
    * the loop.
    */
-   png_size_t rb;
+   png_debug(1, "in png_read_filter_row_paeth3_sse2");
   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;
+   int 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);
+      __m128i pa = _mm_sub_epi16(b,c);

      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
+      __m128i 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);
+      __m128i pc = _mm_add_epi16(pa,pb);

      pa = abs_i16(pa);  /* |p-a| */
      pb = abs_i16(pb);  /* |p-b| */
      pc = abs_i16(pc);  /* |p-c| */

-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
+      __m128i 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));
+      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
+                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
+                                                                     c));

      /* Note `_epi8`: we need addition to wrap modulo 255. */
      d = _mm_add_epi8(d, nearest);
@@ -306,27 +283,26 @@ void png_read_filter_row_paeth3_sse2(png_row_infop row_info, png_bytep row,
      /* 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);
+      __m128i pa = _mm_sub_epi16(b,c);

      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
+      __m128i 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);
+      __m128i pc = _mm_add_epi16(pa,pb);

      pa = abs_i16(pa);  /* |p-a| */
      pb = abs_i16(pb);  /* |p-b| */
      pc = abs_i16(pc);  /* |p-c| */

-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
+      __m128i 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,
+      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
                                                                     c));

@@ -356,16 +332,13 @@ void png_read_filter_row_paeth4_sse2(png_row_infop row_info, png_bytep row,
    * Here we zero b and d, which become c and a respectively at the start of
    * the loop.
    */
-   png_size_t rb;
+   png_debug(1, "in png_read_filter_row_paeth4_sse2");
   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) {
+   int rb = row_info->rowbytes;
+   while (rb > 0) {
      /* It's easiest to do this math (particularly, deal with pc) with 16-bit
       * intermediates.
       */
@@ -373,22 +346,22 @@ void png_read_filter_row_paeth4_sse2(png_row_infop row_info, png_bytep row,
      a = d; d = _mm_unpacklo_epi8(load4(row ), zero);

      /* (p-a) == (a+b-c - a) == (b-c) */
-      pa = _mm_sub_epi16(b,c);
+      __m128i pa = _mm_sub_epi16(b,c);

      /* (p-b) == (a+b-c - b) == (a-c) */
-      pb = _mm_sub_epi16(a,c);
+      __m128i 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);
+      __m128i pc = _mm_add_epi16(pa,pb);

      pa = abs_i16(pa);  /* |p-a| */
      pb = abs_i16(pb);  /* |p-b| */
      pc = abs_i16(pc);  /* |p-c| */

-      smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
+      __m128i 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,
+      __m128i nearest  = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
                         if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
                                                                     c));

--- a/contrib/intel/intel_init.c
+++ b/contrib/intel/intel_init.c
@@ -1,18 +1,19 @@

 /* 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
+ * Copyright (c) 2016 Google, Inc.
+ * Written by Mike Klein and Matt Sarett
+ * Derived from arm/arm_init.c, which was
+ * Copyright (c) 2014,2016 Glenn Randers-Pehrson
 *
- * Last changed in libpng 1.6.29 [March 16, 2017]
+ * Last changed in libpng 1.6.22 [May 26, 2016]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

-#include "../pngpriv.h"
+#include "../../pngpriv.h"

 #ifdef PNG_READ_SUPPORTED
 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
--- a/contrib/intel/intel_sse.patch
+++ b/contrib/intel/intel_sse.patch
@@ -0,0 +1,190 @@
+diff --git a/configure.ac b/configure.ac
+--- a/configure.ac	2016-08-29 11:46:27.000000000 -0400
+++ b/configure.ac	2016-08-29 16:57:03.866355018 -0400
+@@ -386,16 +386,51 @@ AC_ARG_ENABLE([mips-msa],
+ # future host CPU does not match 'mips*')
+ 
+ AM_CONDITIONAL([PNG_MIPS_MSA],
+    [test "$enable_mips_msa" != 'no' &&
+     case "$host_cpu" in
+       mipsel*|mips64el*) :;;
+     esac])
+ 
+# INTEL
+# =====
+#
+# INTEL SSE (SIMD) support.
+
+AC_ARG_ENABLE([intel-sse],
+   AS_HELP_STRING([[[--enable-intel-sse]]],
+      [Enable Intel SSE optimizations: =no/off, yes/on:]
+      [no/off: disable the optimizations;]
+      [yes/on: enable the optimizations.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling:
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
+                   [Disable Intel SSE optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_intel_sse=no;;
+      yes|on)
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
+                   [Enable Intel SSE optimizations]);;
+      *)
+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
+   esac])
+
+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
+# or where Intel optimizations were explicitly requested (this allows a
+# fallback if a future host CPU does not match 'x86*')
+AM_CONDITIONAL([PNG_INTEL_SSE],
+   [test "$enable_intel_sse" != 'no' &&
+    case "$host_cpu" in
+      i?86|x86_64) :;;
+      *)    test "$enable_intel_sse" != '';;
+    esac])
+
+ AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
+ 
+ # Config files, substituting as above
+ AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
+ AC_CONFIG_FILES([libpng-config:libpng-config.in],
+    [chmod +x libpng-config])
+ 
+ AC_OUTPUT
+diff --git a/Makefile.am b/Makefile.am
+--- a/Makefile.am	2016-08-29 11:46:27.000000000 -0400
+++ b/Makefile.am	2016-08-29 16:57:45.955528215 -0400
+@@ -97,16 +97,21 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SO
+ 	arm/filter_neon.S arm/filter_neon_intrinsics.c
+ endif
+ 
+ if PNG_MIPS_MSA
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
+ 	mips/filter_msa_intrinsics.c
+ endif
+ 
+if PNG_INTEL_SSE
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
+    contrib/intel/filter_sse2_intrinsics.c
+endif
+
+ nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
+ 
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
+ 	-version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
+ 
+ if HAVE_LD_VERSION_SCRIPT
+ #   Versioned symbols and restricted exports
+ if HAVE_SOLARIS_LD
+diff --git a/pngpriv.h b/pngpriv.h
+--- debug16/pngpriv.h	2016-08-30 10:46:36.000000000 -0400
+++ libpng16/pngpriv.h	2016-08-30 11:57:25.672280202 -0400
+@@ -185,16 +185,52 @@
+ #ifndef PNG_MIPS_MSA_OPT
+ #  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
+ #     define PNG_MIPS_MSA_OPT 2
+ #  else
+ #     define PNG_MIPS_MSA_OPT 0
+ #  endif
+ #endif
+ 
+#ifndef PNG_INTEL_SSE_OPT
+#   ifdef PNG_INTEL_SSE
+      /* Only check for SSE if the build configuration has been modified to
+       * enable SSE optimizations.  This means that these optimizations will
+       * be off by default.  See contrib/intel for more details.
+       */
+#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
+       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
+#         define PNG_INTEL_SSE_OPT 1
+#      endif
+#   endif
+#endif
+
+#if PNG_INTEL_SSE_OPT > 0
+#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
+#      if defined(__SSE4_1__) || defined(__AVX__)
+          /* We are not actually using AVX, but checking for AVX is the best
+             way we can detect SSE4.1 and SSSE3 on MSVC.
+          */
+#         define PNG_INTEL_SSE_IMPLEMENTATION 3
+#      elif defined(__SSSE3__)
+#         define PNG_INTEL_SSE_IMPLEMENTATION 2
+#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
+#         define PNG_INTEL_SSE_IMPLEMENTATION 1
+#      else
+#         define PNG_INTEL_SSE_IMPLEMENTATION 0
+#      endif
+#   endif
+
+#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
+#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
+#   endif
+#endif
+
+ #if PNG_MIPS_MSA_OPT > 0
+ #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
+ #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
+ #     if defined(__mips_msa)
+ #        if defined(__clang__)
+ #        elif defined(__GNUC__)
+ #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
+ #              define PNG_MIPS_MSA_IMPLEMENTATION 2
+@@ -1251,16 +1287,31 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
+ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
+     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
+     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
+     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+ #endif
+ 
+#if PNG_INTEL_SSE_IMPLEMENTATION > 0
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+#endif
+
+ /* Choose the best filter to use and filter the row data */
+ PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
+     png_row_infop row_info),PNG_EMPTY);
+ 
+ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+ PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
+    png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
+    /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
+@@ -1986,16 +2037,21 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_O
+ PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
+    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
+ #endif
+ 
+ #if PNG_MIPS_MSA_OPT > 0
+ PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
+    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
+ #endif
+
+#  if PNG_INTEL_SSE_IMPLEMENTATION > 0
+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
+   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
+#  endif
+ #endif
+ 
+ PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
+    png_const_charp key, png_bytep new_key), PNG_EMPTY);
+ 
+ /* Maintainer: Put new private prototypes here ^ */
+ 
+ #include "pngdebug.h"
--- a/contrib/libtests/pngimage.c
+++ b/contrib/libtests/pngimage.c
@@ -927,7 +927,7 @@ update_display(struct display *dp)
   png_structp pp;
   png_infop   ip;

-   /* Now perform the initial read with a 0 transform. */
+   /* Now perform the initial read with a 0 tranform. */
   read_png(dp, &dp->original_file, "original read", 0/*no transform*/);

   /* Move the result to the 'original' fields */
--- 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) 2013-2016 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.24 [August 4, 2016]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -1142,7 +1143,7 @@ get_pixel(png_uint_32 format))(Pixel *p, png_const_voidp pb)
   }
 }

-/* Conversion between pixel formats.  The code above effectively eliminates the
+/* Convertion between pixel formats.  The code above effectively eliminates the
 * component ordering changes leaving three basic changes:
 *
 * 1) Remove an alpha channel by pre-multiplication or compositing on a
@@ -2036,7 +2037,7 @@ typedef struct
   /* Precalculated values: */
   int          in_opaque;   /* Value of input alpha that is opaque */
   int          is_palette;  /* Sample values come from the palette */
-   int          accumulate;  /* Accumulate component errors (don't log) */
+   int          accumulate;  /* Accumlate component errors (don't log) */
   int          output_8bit; /* Output is 8-bit (else 16-bit) */

   void (*in_gp)(Pixel*, png_const_voidp);
@@ -2610,9 +2611,9 @@ 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 +2746,22 @@ 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 +2881,10 @@ 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 +2900,10 @@ 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;
--- 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 1.6.26 [October 20, 2016]
+ * Copyright (c) 2015,2016 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
 * This code is released under the libpng license.
@@ -85,7 +85,7 @@ typedef png_byte *png_const_bytep;
 #define PNG_WRITE_16BIT_SUPPORTED
 #define PNG_READ_16BIT_SUPPORTED

-/* This comes from pnglibconf.h after 1.5: */
+/* This comes from pnglibconf.h afer 1.5: */
 #define PNG_FP_1 100000
 #define PNG_GAMMA_THRESHOLD_FIXED\
   ((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
@@ -114,7 +114,6 @@ 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 +210,6 @@ 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,
@@ -622,7 +614,7 @@ 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;
         }
@@ -1098,7 +1090,7 @@ 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*/
 };

--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,8 +1,8 @@

 /* 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 1.6.27 [December 29, 2016]
+ * Copyright (c) 2014-2016 John Cunningham Bowler
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@@ -102,7 +102,7 @@ typedef png_byte *png_const_bytep;
 #define PNG_WRITE_16BIT_SUPPORTED
 #define PNG_READ_16BIT_SUPPORTED

-/* This comes from pnglibconf.h after 1.5: */
+/* This comes from pnglibconf.h afer 1.5: */
 #define PNG_FP_1 100000
 #define PNG_GAMMA_THRESHOLD_FIXED\
   ((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
@@ -5001,7 +5001,7 @@ standard_display_init(standard_display *dp, png_store* ps, png_uint_32 id,
   dp->npalette = 0;
   /* Preset the transparent color to black: */
   memset(&dp->transparent, 0, sizeof dp->transparent);
-   /* Preset the palette to full intensity/opaque throughout: */
+   /* Preset the palette to full intensity/opaque througout: */
   memset(dp->palette, 0xff, sizeof dp->palette);
 }

@@ -5270,7 +5270,7 @@ standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
    */
   standard_palette_validate(dp, pp, pi);

-   /* In any case always check for a transparent color (notice that the
+   /* In any case always check for a tranparent color (notice that the
    * colour type 3 case must not give a successful return on the get_tRNS call
    * with these arguments!)
    */
@@ -6584,16 +6584,16 @@ 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];
@@ -6780,7 +6780,7 @@ transform_image_validate(transform_display *dp, png_const_structp pp,
   store_image_check(dp->this.ps, pp, 0);

   /* Read the palette corresponding to the output if the output colour type
-    * indicates a palette, otherwise set out_palette to garbage.
+    * indicates a palette, othewise set out_palette to garbage.
    */
   if (out_ct == PNG_COLOR_TYPE_PALETTE)
   {
@@ -7742,11 +7742,13 @@ 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);
      }
   }

@@ -7991,7 +7993,7 @@ image_transform_png_set_rgb_to_gray_mod(const image_transform *this,
         /* Now calculate the actual gray values.  Although the error in the
          * coefficients depends on whether they were specified on the command
          * line (in which case truncation to 15 bits happened) or not (rounding
-          * was used) the maximum error in an individual coefficient is always
+          * was used) the maxium error in an individual coefficient is always
          * 2/32768, because even in the rounding case the requirement that
          * coefficients add up to 32768 can cause a larger rounding error.
          *
@@ -8207,7 +8209,7 @@ image_transform_png_set_rgb_to_gray_mod(const image_transform *this,
      that->bluef = that->greenf = that->redf = gray;
      that->bluee = that->greene = that->rede = err;

-      /* The sBIT is the minimum of the three colour channel sBITs. */
+      /* The sBIT is the minium of the three colour channel sBITs. */
      if (that->red_sBIT > that->green_sBIT)
         that->red_sBIT = that->green_sBIT;
      if (that->red_sBIT > that->blue_sBIT)
@@ -9746,7 +9748,7 @@ gamma_component_validate(const char *name, const validate_info *vi,
       *
       * pngvalid calculations:
       *  input_sample: linear result; i linearized and composed, range 0..1
-       *  encoded_sample: encoded result; input_sample scaled to output bit depth
+       *  encoded_sample: encoded result; input_sample scaled to ouput bit depth
       *
       * libpng calculations:
       *  output: linear result; od scaled to 0..1 and linearized
@@ -9994,9 +9996,9 @@ 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:
@@ -10183,10 +10185,10 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
    * Since the library must quantize the output to 8 or 16 bits there is
    * a fundamental limit on the accuracy of the output of +/-.5 - this
    * quantization limit is included in addition to the other limits
-    * specified by the parameters to the API.  (Effectively, add .5
+    * specified by the paramaters to the API.  (Effectively, add .5
    * everywhere.)
    *
-    * The behavior of the 'sbit' parameter is defined by section 12.5
+    * The behavior of the 'sbit' paramter is defined by section 12.5
    * (sample depth scaling) of the PNG spec.  That section forces the
    * decoder to assume that the PNG values have been scaled if sBIT is
    * present:
@@ -11729,7 +11731,7 @@ int main(int argc, char **argv)

   /* Some default values (set the behavior for 'make check' here).
    * These values simply control the maximum error permitted in the gamma
-    * transformations.  The practical limits for human perception are described
+    * transformations.  The practial limits for human perception are described
    * below (the setting for maxpc16), however for 8 bit encodings it isn't
    * possible to meet the accepted capabilities of human vision - i.e. 8 bit
    * images can never be good enough, regardless of encoding.
--- a/contrib/libtests/tarith.c
+++ b/contrib/libtests/tarith.c
@@ -176,7 +176,7 @@ int validation_ascii_to_fp(int count, int argc, char **argv)
      }
      else if (PNG_FP_IS_POSITIVE(state) && !(test > 0))
      {
-         fprintf(stderr, "%g[%d] -> '%s' but positive value not so reported\n",
+         fprintf(stderr, "%g[%d] -> '%s' but postive value not so reported\n",
            test, precision, buffer);
         failed = 1;
         assert(!PNG_FP_IS_NEGATIVE(state));
--- a/contrib/oss-fuzz/Dockerfile
+++ b/contrib/oss-fuzz/Dockerfile
@@ -1,25 +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
-
-RUN git clone --depth 1 https://github.com/madler/zlib.git
-RUN git clone --depth 1 https://github.com/glennrp/libpng.git
-RUN cp libpng/contrib/oss-fuzz/build.sh $SRC
-WORKDIR libpng
--- 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 is a copy of the file used by oss-fuzz. build.sh,
-   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
@@ -1,51 +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 1.6.35 [March 6, 2018]
-#
-# Revisions by Glenn Randers-Pehrson, 2017:
-# 1. Build only the library, not the tools (changed "make -j$(nproc) all" to
-#     "make -j$(nproc) libpng16.la").
-# 2. Disabled WARNING and WRITE options in pnglibconf.dfa.
-# 3. Build zlib alongside libpng
-################################################################################
-
-# Disable logging via library build configuration control.
-cat scripts/pnglibconf.dfa | \
-  sed -e "s/option STDIO/option STDIO disabled/" \
-      -e "s/option WARNING /option WARNING disabled/" \
-      -e "s/option WRITE enables WRITE_INT_FUNCTIONS/option WRITE disabled/" \
-> scripts/pnglibconf.dfa.temp
-mv scripts/pnglibconf.dfa.temp scripts/pnglibconf.dfa
-
-# build the libpng library.
-autoreconf -f -i
-./configure --with-libpng-prefix=OSS_FUZZ_
-make -j$(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
@@ -1,190 +0,0 @@
-
-// libpng_read_fuzzer.cc
-// Copyright 2017-2018 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 1.6.35 [March 6, 2018]
-
-// 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.
-// 5. adding calls to png_set_*() transforms commonly used by browsers.
-
-#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);
-
-  // 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;
-  }
-
-  // Set several transforms that browsers typically use:
-  png_set_gray_to_rgb(png_handler.png_ptr);
-  png_set_expand(png_handler.png_ptr);
-  png_set_packing(png_handler.png_ptr);
-  png_set_scale_16(png_handler.png_ptr);
-  png_set_tRNS_to_alpha(png_handler.png_ptr);
-
-  int passes = png_set_interlace_handling(png_handler.png_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));
-
-  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/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
@@ -17,7 +17,7 @@ express or implied warranty.
 Some history
 ------------
 Soon after the creation of PNG in 1995, the need was felt for a set of
-pnmtopng / pngtopnm utilities. Independently Alexander Lehmann and I
+pnmtopng / pngtopnm utilities. Independantly Alexander Lehmann and I
 (Willem van Schaik) started such a project. Luckily we discovered this
 and merged the two together into pnmtopng.tar.gz, which is available
 from a/o ftp://ftp.simplesystems.org/pub/libpng/png/.
--- a/contrib/pngminus/png2pnm.bat
+++ b/contrib/pngminus/png2pnm.bat
@@ -7,7 +7,7 @@ png2pnm.exe -noraw ..\pngsuite\basn0g16.png basn0g16.pgm
 REM -- full-color
 png2pnm.exe -noraw ..\pngsuite\basn2c08.png basn2c08.ppm
 png2pnm.exe -noraw ..\pngsuite\basn2c16.png basn2c16.ppm
-REM -- paletted
+REM -- palletted
 png2pnm.exe -noraw ..\pngsuite\basn3p01.png basn3p01.ppm
 png2pnm.exe -noraw ..\pngsuite\basn3p02.png basn3p02.ppm
 png2pnm.exe -noraw ..\pngsuite\basn3p04.png basn3p04.ppm
@@ -27,7 +27,7 @@ png2pnm.exe -raw ..\pngsuite\basn0g16.png rawn0g16.pgm
 REM -- full-color
 png2pnm.exe -raw ..\pngsuite\basn2c08.png rawn2c08.ppm
 png2pnm.exe -raw ..\pngsuite\basn2c16.png rawn2c16.ppm
-REM -- paletted
+REM -- palletted
 png2pnm.exe -raw ..\pngsuite\basn3p01.png rawn3p01.ppm
 png2pnm.exe -raw ..\pngsuite\basn3p02.png rawn3p02.ppm
 png2pnm.exe -raw ..\pngsuite\basn3p04.png rawn3p04.ppm
--- 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 at 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/png2pnm.sh
+++ b/contrib/pngminus/png2pnm.sh
@@ -8,7 +8,7 @@
 # -- full-color
 ./png2pnm -noraw ../pngsuite/basn2c08.png basn2c08.ppm
 ./png2pnm -noraw ../pngsuite/basn2c16.png basn2c16.ppm
-# -- paletted
+# -- palletted
 ./png2pnm -noraw ../pngsuite/basn3p01.png basn3p01.ppm
 ./png2pnm -noraw ../pngsuite/basn3p02.png basn3p02.ppm
 ./png2pnm -noraw ../pngsuite/basn3p04.png basn3p04.ppm
@@ -28,7 +28,7 @@
 # -- full-color
 ./png2pnm -raw ../pngsuite/basn2c08.png rawn2c08.ppm
 ./png2pnm -raw ../pngsuite/basn2c16.png rawn2c16.ppm
-# -- paletted
+# -- palletted
 ./png2pnm -raw ../pngsuite/basn3p01.png rawn3p01.ppm
 ./png2pnm -raw ../pngsuite/basn3p02.png rawn3p02.ppm
 ./png2pnm -raw ../pngsuite/basn3p04.png rawn3p04.ppm
--- a/contrib/pngminus/pnm2png.bat
+++ b/contrib/pngminus/pnm2png.bat
@@ -7,7 +7,7 @@ pnm2png.exe basn0g16.pgm basn0g16.png
 REM -- full-color
 pnm2png.exe basn2c08.ppm basn2c08.png
 pnm2png.exe basn2c16.ppm basn2c16.png
-REM -- paletted
+REM -- palletted
 pnm2png.exe basn3p01.ppm basn3p01.png
 pnm2png.exe basn3p02.ppm basn3p02.png
 pnm2png.exe basn3p04.ppm basn3p04.png
@@ -27,7 +27,7 @@ pnm2png.exe rawn0g16.pgm rawn0g16.png
 REM -- full-color
 pnm2png.exe rawn2c08.ppm rawn2c08.png
 pnm2png.exe rawn2c16.ppm rawn2c16.png
-REM -- paletted
+REM -- palletted
 pnm2png.exe rawn3p01.ppm rawn3p01.png
 pnm2png.exe rawn3p02.ppm rawn3p02.png
 pnm2png.exe rawn3p04.ppm rawn3p04.png
--- 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 at 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/pngminus/pnm2png.sh
+++ b/contrib/pngminus/pnm2png.sh
@@ -8,7 +8,7 @@
 # -- full-color
 ./pnm2png basn2c08.ppm basn2c08.png
 ./pnm2png basn2c16.ppm basn2c16.png
-# -- paletted
+# -- palletted
 ./pnm2png basn3p01.ppm basn3p01.png
 ./pnm2png basn3p02.ppm basn3p02.png
 ./pnm2png basn3p04.ppm basn3p04.png
@@ -28,7 +28,7 @@
 # -- full-color
 ./pnm2png rawn2c08.ppm rawn2c08.png
 ./pnm2png rawn2c16.ppm rawn2c16.png
-# -- paletted
+# -- palletted
 ./pnm2png rawn3p01.ppm rawn3p01.png
 ./pnm2png rawn3p02.ppm rawn3p02.png
 ./pnm2png rawn3p04.ppm rawn3p04.png
--- a/contrib/pngsuite/README
+++ b/contrib/pngsuite/README
@@ -16,8 +16,6 @@ chunks, etc.
 The "ft*.png" images are "free/libre" replacements for the transparent
 corresponding t*.png images in the PngSuite.

-The "i*.png" images are the same images, but interlaced.
-
 The images in this directory represent the basic PNG color-types:
 grayscale (1-16 bit deep), full color (8 or 16 bit), paletted
 (1-8 bit) and grayscale or color images with alpha channel. You
--- a/contrib/pngsuite/bad_interlace_conversions.txt
+++ b/contrib/pngsuite/bad_interlace_conversions.txt
@@ -1,9 +0,0 @@
-basn0g01.png
-basn0g02.png
-basn0g04.png
-basn3p01.png
-basn3p02.png
-basn3p04.png
-ftbbn0g01.png
-ftbbn0g02.png
-ftbbn0g04.png
--- a/contrib/pngsuite/ibasn0g08.png
+++ b/contrib/pngsuite/ibasn0g08.png
--- a/contrib/pngsuite/ibasn0g16.png
+++ b/contrib/pngsuite/ibasn0g16.png
--- a/contrib/pngsuite/ibasn2c08.png
+++ b/contrib/pngsuite/ibasn2c08.png
--- a/contrib/pngsuite/ibasn2c16.png
+++ b/contrib/pngsuite/ibasn2c16.png
--- a/contrib/pngsuite/ibasn3p08.png
+++ b/contrib/pngsuite/ibasn3p08.png
--- a/contrib/pngsuite/ibasn4a08.png
+++ b/contrib/pngsuite/ibasn4a08.png
--- a/contrib/pngsuite/ibasn4a16.png
+++ b/contrib/pngsuite/ibasn4a16.png
--- a/contrib/pngsuite/ibasn6a08.png
+++ b/contrib/pngsuite/ibasn6a08.png
--- a/contrib/pngsuite/ibasn6a16.png
+++ b/contrib/pngsuite/ibasn6a16.png
--- a/contrib/pngsuite/iftbbn2c16.png
+++ b/contrib/pngsuite/iftbbn2c16.png
--- a/contrib/pngsuite/iftbbn3p08.png
+++ b/contrib/pngsuite/iftbbn3p08.png
--- a/contrib/pngsuite/iftbgn2c16.png
+++ b/contrib/pngsuite/iftbgn2c16.png
--- a/contrib/pngsuite/iftbgn3p08.png
+++ b/contrib/pngsuite/iftbgn3p08.png
--- a/contrib/pngsuite/iftbrn2c08.png
+++ b/contrib/pngsuite/iftbrn2c08.png
--- a/contrib/pngsuite/iftbwn0g16.png
+++ b/contrib/pngsuite/iftbwn0g16.png
--- a/contrib/pngsuite/iftbwn3p08.png
+++ b/contrib/pngsuite/iftbwn3p08.png
--- a/contrib/pngsuite/iftbyn3p08.png
+++ b/contrib/pngsuite/iftbyn3p08.png
--- a/contrib/pngsuite/iftp0n0g08.png
+++ b/contrib/pngsuite/iftp0n0g08.png
--- a/contrib/pngsuite/iftp0n2c08.png
+++ b/contrib/pngsuite/iftp0n2c08.png
--- a/contrib/pngsuite/iftp0n3p08.png
+++ b/contrib/pngsuite/iftp0n3p08.png
--- a/contrib/pngsuite/iftp1n3p08.png
+++ b/contrib/pngsuite/iftp1n3p08.png
--- a/contrib/pngsuite/interlaced/README
+++ b/contrib/pngsuite/interlaced/README
@@ -1,2 +0,0 @@
-
-These images fail the "pngimage-quick" and "pngimage-full" tests.
--- a/contrib/pngsuite/interlaced/ibasn0g01.png
+++ b/contrib/pngsuite/interlaced/ibasn0g01.png
--- a/contrib/pngsuite/interlaced/ibasn0g02.png
+++ b/contrib/pngsuite/interlaced/ibasn0g02.png
--- a/contrib/pngsuite/interlaced/ibasn0g04.png
+++ b/contrib/pngsuite/interlaced/ibasn0g04.png
--- a/contrib/pngsuite/interlaced/ibasn3p01.png
+++ b/contrib/pngsuite/interlaced/ibasn3p01.png
--- a/contrib/pngsuite/interlaced/ibasn3p02.png
+++ b/contrib/pngsuite/interlaced/ibasn3p02.png
--- a/contrib/pngsuite/interlaced/ibasn3p04.png
+++ b/contrib/pngsuite/interlaced/ibasn3p04.png
--- a/contrib/pngsuite/interlaced/iftbbn0g01.png
+++ b/contrib/pngsuite/interlaced/iftbbn0g01.png
--- a/contrib/pngsuite/interlaced/iftbbn0g02.png
+++ b/contrib/pngsuite/interlaced/iftbbn0g02.png
--- a/contrib/pngsuite/interlaced/iftbbn0g04.png
+++ b/contrib/pngsuite/interlaced/iftbbn0g04.png
--- 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 POWERPC_VSX 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/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/Show More
+++ b/Show More
				`@@ -1,2 +0,0 @@`

				`These images fail the "pngimage-quick" and "pngimage-full" tests.`