Harden a vestigial check against overflow inside png_zalloc

Reported-by: Sergio Atienza Pastor, MTP Métodos y Tecnología

.appveyor.yml

@@ -0,0 +1,81 @@
+version: 1.6.x-{build}
+
+branches:
+  except:
+    - /libpng[0-1][0-8]/
+    - /v[0-1][.][0-8][.][0-9]+/
+
+image:
+  - Visual Studio 2022
+
+shallow_clone: true
+
+environment:
+  matrix:
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: x86
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: x64
+    - TOOLCHAIN: vstudio
+      AUTOMATION: cmake
+      ARCH: arm64
+    - TOOLCHAIN: llvm
+      AUTOMATION: cmake
+      ARCH: x64
+    - TOOLCHAIN: msys2
+      AUTOMATION: cmake
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: cmake
+      ARCH: x86_64
+    - TOOLCHAIN: msys2
+      AUTOMATION: configure
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: configure
+      ARCH: x86_64
+    - TOOLCHAIN: msys2
+      AUTOMATION: makefiles
+      ARCH: i686
+    - TOOLCHAIN: msys2
+      AUTOMATION: makefiles
+      ARCH: x86_64
+
+install:
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\tools\vcpkg\vcpkg.exe install zlib:%ARCH%-windows'
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\tools\vcpkg\vcpkg.exe integrate install'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\tools\vcpkg\vcpkg.exe install zlib:%ARCH%-windows'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\tools\vcpkg\vcpkg.exe integrate install'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="cmake" C:\msys64\usr\bin\pacman.exe -S --noconfirm mingw-w64-%ARCH%-cmake mingw-w64-%ARCH%-ninja'
+
+before_build:
+  - 'if "%TOOLCHAIN%"=="vstudio" set CI_CMAKE_GENERATOR=Visual Studio 17 2022'
+  - 'if "%TOOLCHAIN%"=="vstudio" set CI_CMAKE_TOOLCHAIN_FILE=C:\tools\vcpkg\scripts\buildsystems\vcpkg.cmake'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="x86" set CI_CMAKE_GENERATOR_PLATFORM=Win32'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="x64" set CI_CMAKE_GENERATOR_PLATFORM=x64'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="arm64" set CI_CMAKE_GENERATOR_PLATFORM=ARM64'
+  - 'if "%TOOLCHAIN%"=="vstudio" if "%ARCH%"=="arm64" set CI_CMAKE_VARS=-DPNG_TESTS=0'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CMAKE_GENERATOR=Ninja'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CMAKE_TOOLCHAIN_FILE=C:\tools\vcpkg\scripts\buildsystems\vcpkg.cmake'
+  - 'if "%TOOLCHAIN%"=="llvm" set CI_CC=clang'
+  - 'if "%TOOLCHAIN%"=="msys2" set CI_CMAKE_GENERATOR=Ninja'
+  - 'if "%TOOLCHAIN%"=="msys2" set CI_CC=gcc'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%ARCH%"=="i686" set MSYSTEM=MINGW32'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%ARCH%"=="x86_64" set MSYSTEM=MINGW64'
+  - 'set CI_CMAKE_BUILD_FLAGS=-j2'
+  - 'set CI_CTEST_FLAGS=-j2'
+  - 'set CI_MAKE_FLAGS=-j2'
+  - 'set CI_MAKEFILES=scripts/makefile.gcc scripts/makefile.msys scripts/makefile.std'
+
+build_script:
+  - 'if "%TOOLCHAIN%"=="vstudio" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="llvm" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="cmake" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_cmake.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="configure" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_configure.sh"'
+  - 'if "%TOOLCHAIN%"=="msys2" if "%AUTOMATION%"=="makefiles" C:\msys64\usr\bin\bash.exe -l "%APPVEYOR_BUILD_FOLDER%\ci\ci_verify_makefiles.sh"'
+
+cache:
+  - 'C:\tools\vcpkg\installed'
+  - 'C:\msys64\var\cache\pacman'

.cmake-format.yaml

@@ -0,0 +1,94 @@
+# https://pypi.org/project/cmakelang
+# https://github.com/cheshirekow/cmake_format
+
+# ----------------------
+# Options for formatting
+# ----------------------
+
+# How wide to allow formatted cmake files
+# TODO: Reflow the CMake files to allow setting the maximum line width to 100.
+line_width: 255
+
+# How many spaces to tab for indent
+tab_size: 2
+
+# If true, lines are indented using tab characters (utf-8 0x09) instead of
+# <tab_size> space characters (utf-8 0x20). In cases where the layout would
+# require a fractional tab character, the behavior of the fractional
+# indentation is governed by <fractional_tab_policy>
+use_tabchars: false
+
+# If <use_tabchars> is True, then the value of this variable indicates how
+# fractional indentions are handled during whitespace replacement. If set to
+# 'use-space', fractional indentation is left as spaces (utf-8 0x20). If set
+# to `round-up` fractional indentation is replaced with a single tab character
+# (utf-8 0x09) effectively shifting the column to the next tabstop
+fractional_tab_policy: "use-space"
+
+# Enable comment markup parsing and reflow
+enable_markup: false
+
+# -------------------
+# Options for linting
+# -------------------
+
+# Lint codes to disable
+disabled_codes: [
+  # TODO:
+  # Reconcile the CMake variable names with the patterns below, then
+  # re-enable the "invalid variable name XXX" messages.
+  "C0103",
+
+  # TODO:
+  # Add brief COMMENT arguments to the `add_custom_target` commands.
+  "C0113",
+]
+
+# Regular expression pattern describing valid function names
+function_pattern: "[0-9a-z_]+"
+
+# Regular expression pattern describing valid macro names
+macro_pattern: "[0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with global
+# (cache) scope
+global_var_pattern: "[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with global
+# scope (but internal semantic)
+internal_var_pattern: "_[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for variables with local
+# scope
+local_var_pattern: "[a-z][a-z0-9_]+"
+
+# Regular expression pattern describing valid names for privatedirectory
+# variables
+private_var_pattern: "_[0-9a-z_]+"
+
+# Regular expression pattern describing valid names for public directory
+# variables
+public_var_pattern: "[A-Z][0-9A-Z_]+"
+
+# Regular expression pattern describing valid names for function/macro
+# arguments and loop variables.
+argument_var_pattern: "[a-z][a-z0-9_]+"
+
+# Regular expression pattern describing valid names for keywords used in
+# functions or macros
+keyword_pattern: "[A-Z][0-9A-Z_]+"
+
+# In the heuristic for C0201, how many conditionals to match within a loop in
+# before considering the loop a parser
+max_conditionals_custom_parser: 2
+
+# Require at least this many newlines between statements;
+# require no more than this many newlines between statements;
+# etc.
+min_statement_spacing: 1
+max_statement_spacing: 2
+max_returns: 6
+max_branches: 12
+max_arguments: 5
+max_localvars: 15
+max_statements: 50

.editorconfig

@@ -0,0 +1,55 @@
+# https://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.txt]
+indent_size = unset
+indent_style = space
+
+[*.[chS]]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 80
+
+[*.dfa]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 80
+
+[*.awk]
+indent_size = 3
+indent_style = space
+max_doc_length = 80
+max_line_length = 100
+
+[*.cmake]
+indent_size = 2
+indent_style = space
+max_doc_length = 80
+max_line_length = 100
+
+[*.sh]
+indent_size = 4
+indent_style = space
+max_doc_length = 100
+max_line_length = 100
+
+[{Makefile.in,aclocal.m4,ltmain.sh}]
+indent_size = unset
+indent_style = unset
+insert_final_newline = unset
+max_doc_length = unset
+max_line_length = unset
+trim_trailing_whitespace = unset
+
+[COMMIT_EDITMSG]
+indent_style = space
+max_doc_length = unset
+max_line_length = 72

.editorconfig-checker.json

@@ -0,0 +1,9 @@
+{
+  "Disable": {
+    "IndentSize": true
+  },
+  "Exclude": [
+    ".git/",
+    "out/"
+  ]
+}

.github/workflows/lint.yml

@@ -0,0 +1,31 @@
+name: Linting libpng
+
+on:
+  push:
+    branches:
+      - libpng16
+      - libpng18
+  pull_request:
+    branches:
+      - libpng16
+      - libpng18
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Set up the cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pip
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/pip.txt') }}
+          restore-keys: ${{ runner.os }}-pip-
+      - name: Install yamllint
+        run: pip install yamllint
+      - name: Install editorconfig-checker
+        uses: editorconfig-checker/action-editorconfig-checker@main
+      - name: Check out the code
+        uses: actions/checkout@v4
+      - name: Run the linting script
+        run: bash ./ci/ci_lint.sh

.gitignore

@@ -0,0 +1,159 @@
+# Prerequisites
+*.d
+
+# Precompiled headers
+*.gch
+*.pch
+
+# Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Linker output files
+*.exp
+*.ilk
+*.map
+
+# Compiled dynamic libraries
+*.dll
+*.dylib
+*.so
+*.so.*
+
+# Compiled static libraries
+*.a
+*.la
+*.lai
+*.lib
+
+# Compiled executables
+*.app/
+*.exe
+a.out
+
+# Debug files
+*.dSYM/
+*.idb
+*.pdb
+*.su
+
+# Tag files
+TAGS
+.TAGS
+!TAGS/
+tags
+.tags
+!tags/
+gtags.files
+GTAGS
+GRTAGS
+GPATH
+GSYMS
+cscope.files
+cscope.out
+cscope.*.out
+
+# Text editing and text processing artifacts
+\#*\#
+.\#*
+[._]*.sw[a-p]
+[._]sw[a-p]
+*.bak
+*.orig
+*.rej
+*.tmp
+*~
+
+# IDE files and directories
+## Eclipse
+.cproject/
+.project/
+.settings/
+## Embarcadero RAD Studio
+*.cbproj.*
+__recovery/
+## JetBrains
+.idea/
+## NetBeans
+nbbuild/
+nbdist/
+nbproject/
+## Visual Studio
+.vs/
+### Visual Studio user files
+*.rsuser
+*.sln.docstates
+*.suo
+*.user
+*.userprefs
+### Visual Studio cache files (for older versions)
+*.aps
+*.ncb
+*.opensdf
+*.sdf
+*.VC.db
+*.VC.opendb
+ipch/
+## Visual Studio Code
+.vscode/*
+!.vscode/extensions.json
+!.vscode/launch.json
+!.vscode/settings.json
+!.vscode/tasks.json
+## (Various)
+*.*cache
+*.cache*
+[._]*_history
+.history/
+[Bb]ackup*/
+
+# Build, test and CI output directories
+*[Dd]ebug/
+[Dd]ebug*/
+*[Rr]elease/
+[Rr]elease*/
+[._]build*/
+/[Bb]uild*/
+/[Oo]ut/
+
+# Libpng configuration and auxiliary build artifacts
+*.out
+*out.png
+[._]deps/
+[._]libs/
+.dirstamp
+/Makefile
+/autom4te.cache/
+/config*~
+/config.h
+/config.log
+/config.status
+/install*~
+/libpng*-config
+/libpng*.pc
+/libpng.vers
+/libtool
+/stamp-h1
+CMake*.json
+!CMakePresets.json
+CMakeLists.txt.*
+pnglibconf.[ch]
+pnglibconf.dfn
+pnglibconf.pre
+pngprefix.h
+
+# Libpng test programs, scripts and artifacts
+/test-suite.log
+/tests/*.log
+/tests/*.trs
+/png-fix-itxt
+/pngcp
+/pngfix
+/pngimage
+/pngstest
+/pngtest
+/pngunknown
+/pngvalid
+/timepng

.yamllint.yml

@@ -0,0 +1,7 @@
+extends: default
+rules:
+  document-start: disable
+  document-end: disable
+  line-length: disable
+  truthy:
+    check-keys: false

ANNOUNCE

@@ -1,48 +1,53 @@
-Libpng 1.6.35 - July 15, 2018
+libpng 1.6.51.git
+=================
+
+This is a development version, not intended to be a public release.
+It will be replaced by a public release, or by another development
+version, at a later time.
+
+
+libpng 1.6.50 - July 1, 2025
+============================
 
 This is a public release of libpng, intended for use in production code.
 
-Files available for download:
+
+Files available for download
+----------------------------
 
 Source files with LF line endings (for Unix/Linux):
 
-   libpng-1.6.35.tar.xz (LZMA-compressed, recommended)
+ * libpng-1.6.50.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.35.tar.gz
+ * libpng-1.6.50.tar.gz (deflate-compressed)
 
 Source files with CRLF line endings (for Windows):
 
-   lp1635.7z  (LZMA-compressed, recommended)
+ * lpng1650.7z (LZMA-compressed, recommended)
-   lp1635.zip
+ * lpng1650.zip (deflate-compressed)
 
 Other information:
 
-   libpng-1.6.35-README.txt
+ * README.md
-   libpng-1.6.35-LICENSE.txt
+ * LICENSE.md
+ * AUTHORS.md
+ * TRADEMARK.md
 
-Changes since the last public release (1.6.34):
 
-  Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
+Changes from version 1.6.49 to version 1.6.50
-    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.
-  Make png_get_iCCP consistent with man page (allow compression-type argument
-    to be NULL, bug report by Lenard Szolnoki).
-  Replaced the remaining uses of png_size_t with size_t (Cosmin)
-  Fixed the calculation of row_factor in png_check_chunk_length
-    (reported by Thuan Pham in SourceForge issue #278)
-  Added missing parentheses to a macro definition
-    (suggested by "irwir" in GitHub issue #216)
 
-Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+ * Improved the detection of the RVV Extension on the RISC-V platform.
-(subscription required; visit
+   (Contributed by Filip Wasil)
+ * Replaced inline ASM with C intrinsics in the RVV code.
+   (Contributed by Filip Wasil)
+ * Fixed a decoder defect in which unknown chunks trailing IDAT, set
+   to go through the unknown chunk handler, incorrectly triggered
+   out-of-place IEND errors.
+   (Contributed by John Bowler)
+ * Fixed the CMake file for cross-platform builds that require `libm`.
+
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net.
+Subscription is required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe).
+to subscribe.
-
-Glenn R-P

AUTHORS

@@ -0,0 +1,66 @@
+PNG REFERENCE LIBRARY AUTHORS
+=============================
+
+This is the list of PNG Reference Library ("libpng") Contributing
+Authors, for copyright and licensing purposes.
+
+ * Adam Richter
+ * Andreas Dilger
+ * Chris Blume
+ * Cosmin Truta
+ * Dave Martindale
+ * Eric S. Raymond
+ * Gilles Vollant
+ * Glenn Randers-Pehrson
+ * Greg Roelofs
+ * Guy Eric Schalnat
+ * James Yu
+ * John Bowler
+ * Kevin Bracey
+ * Lucas Chollet
+ * Magnus Holmgren
+ * Mandar Sahastrabuddhe
+ * Manfred Schlaegl
+ * Mans Rullgard
+ * Matt Sarett
+ * Mike Klein
+ * Pascal Massimino
+ * Paul Schmidt
+ * Philippe Antoine
+ * Qiang Zhou
+ * Sam Bushell
+ * Samuel Williams
+ * Simon-Pierre Cadieux
+ * Tim Wegner
+ * Tom Lane
+ * Tom Tanner
+ * Vadim Barkov
+ * Willem van Schaik
+ * Zhijie Liang
+ * Apple Inc.
+    - Zixu Wang (王子旭)
+ * Arm Holdings
+    - Richard Townsend
+ * Google LLC
+    - Dan Field
+    - Dragoș Tiselice
+    - Leon Scroggins III
+    - Matt Sarett
+    - Mike Klein
+    - Sami Boukortt
+    - Wan-Teh Chang
+ * Loongson Technology Corporation Ltd.
+    - GuXiWei (顾希伟)
+    - JinBo (金波)
+    - ZhangLixia (张利霞)
+ * Samsung Group
+    - Filip Wasil
+
+The build projects, the build scripts, the test scripts, and other
+files in the "projects", "scripts" and "tests" directories, have
+other copyright owners, but are released under the libpng license.
+
+Some files in the "ci" and "contrib" directories, as well as some
+of the tools-generated files that are distributed with libpng, have
+other copyright owners, and are released under other open source
+licenses.

CHANGES

@@ -204,7 +204,7 @@ Version 0.97 [January, 1998]
   Added simple sRGB support (Glenn R-P)
   Easier conditional compiling, e.g.,
     define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
-    all configurable options can be selected from command-line instead
+    all configurable options can be selected from command line instead
     of having to edit pngconf.h (Glenn R-P)
   Fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
   Added more conditions for png_do_background, to avoid changing
@@ -942,7 +942,7 @@ Version 1.0.8 [July 24, 2000]
 Version 1.0.9beta1 [November 10, 2000]
   Fixed typo in scripts/makefile.hpux
   Updated makevms.com in scripts and contrib/* and contrib/* (Martin Zinser)
-  Fixed seqence-point bug in contrib/pngminus/png2pnm (Martin Zinser)
+  Fixed sequence-point bug in contrib/pngminus/png2pnm (Martin Zinser)
   Changed "cdrom.com" in documentation to "libpng.org"
   Revised pnggccrd.c to get it all working, and updated makefile.gcmmx (Greg).
   Changed type of "params" from voidp to png_voidp in png_read|write_png().
@@ -2295,7 +2295,7 @@ Version 1.4.0beta58 [May 14, 2009]
   Clarified usage of sig_bit versus sig_bit_p in example.c (Vincent Torri)
 
 Version 1.4.0beta59 [May 15, 2009]
-  Reformated sources in libpng style (3-space intentation, comment format)
+  Reformatted sources in libpng style (3-space indentation, comment format)
   Fixed typo in libpng docs (PNG_FILTER_AVE should be PNG_FILTER_AVG)
   Added sections about the git repository and our coding style to the
     documentation
@@ -2661,7 +2661,7 @@ Version 1.4.1beta06 [January 28, 2010]
 
 Version 1.4.1beta07 [February 6, 2010]
   Folded some long lines in the source files.
-  Added defineable PNG_USER_CHUNK_CACHE_MAX, PNG_USER_CHUNK_MALLOC_MAX,
+  Added definable PNG_USER_CHUNK_CACHE_MAX, PNG_USER_CHUNK_MALLOC_MAX,
     and a PNG_USER_LIMITS_SUPPORTED flag.
   Eliminated use of png_ptr->irowbytes and reused the slot in png_ptr as
     png_ptr->png_user_chunk_malloc_max.
@@ -3886,7 +3886,7 @@ Version 1.6.0beta06 [January 24, 2012]
 Version 1.6.0beta07 [January 28, 2012]
   Eliminated Intel icc/icl compiler warnings. The Intel (GCC derived)
     compiler issues slightly different warnings from those issued by the
-    current vesions of GCC. This eliminates those warnings by
+    current versions of GCC. This eliminates those warnings by
     adding/removing casts and small code rewrites.
   Updated configure.ac from autoupdate: added --enable-werror option.
     Also some layout regularization and removal of introduced tab characters
@@ -3919,7 +3919,7 @@ Version 1.6.0beta08 [February 1, 2012]
     version checking to configure.ac
   Improved pngstest speed by not doing redundant tests and add const to
     the background parameter of png_image_finish_read. The --background
-    option is now done automagically only when required, so that commandline
+    option is now done automagically only when required, so that command-line
     option no longer exists.
   Cleaned up pngpriv.h to consistently declare all functions and data.
     Also eliminated PNG_CONST_DATA, which is apparently not needed but we
@@ -4052,7 +4052,7 @@ Version 1.6.0beta16 [March 6, 2012]
     (in fact this is harmless, but the PNG data produced may be sub-optimal).
 
 Version 1.6.0beta17 [March 10, 2012]
-  Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition. 
+  Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition.
   Reject all iCCP chunks after the first, even if the first one is invalid.
   Deflate/inflate was reworked to move common zlib calls into single
     functions [rw]util.c.  A new shared keyword check routine was also added
@@ -4962,7 +4962,7 @@ Version 1.6.13beta01 [July 4, 2014]
   Changed "if defined(__ARM_NEON__)" to
     "if (defined(__ARM_NEON__) || defined(__ARM_NEON))" (James Wu).
   Fixed clang no-warning builds: png_digit was defined but never used.
-    
+
 Version 1.6.13beta02 [July 21, 2014]
   Fixed an incorrect separator ("/" should be "\") in scripts/makefile.vcwin32
     (bug report from Wolfgang S. Kechel).  Bug was introduced in libpng-1.6.11.
@@ -5453,7 +5453,7 @@ Version 1.6.21beta01 [December 11, 2015]
 Version 1.6.21beta02 [December 14, 2015]
   Moved png_check_keyword() from pngwutil.c to pngset.c
   Removed LE/BE dependencies in pngvalid, to 'fix' the current problem
-    in the BigEndian tests by not testing it, making the BE code the same 
+    in the BigEndian tests by not testing it, making the BE code the same
     as the LE version.
   Fixes to pngvalid for various reduced build configurations (eliminate unused
     statics) and a fix for the case in rgb_to_gray when the digitize option
@@ -5517,7 +5517,7 @@ Version 1.6.22beta03 [March 9, 2016]
   Added a common-law trademark notice and export control information
     to the LICENSE file, png.h, and the man page.
   Restored "& 0xff" in png_save_uint_16() and png_save_uint_32() that
-    were accidentally removed from libpng-1.6.17. 
+    were accidentally removed from libpng-1.6.17.
   Changed PNG_INFO_cHNK and PNG_FREE_cHNK from 0xnnnn to 0xnnnnU in png.h
     (Robert C. Seacord).
   Removed dubious "#if INT_MAX" test from png.h that was added to
@@ -5927,7 +5927,7 @@ Version 1.6.32beta03 [August 2, 2017]
     (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().
+  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]
@@ -5950,7 +5950,7 @@ 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).
@@ -6063,9 +6063,224 @@ Version 1.6.35 [July 15, 2018]
   Added missing parentheses to a macro definition
     (suggested by "irwir" in GitHub issue #216)
 
-Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+Version 1.6.36 [December 1, 2018]
-(subscription required; visit
+  Optimized png_do_expand_palette for ARM processors.
-https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+  Improved performance by around 10-22% on a recent ARM Chromebook.
-to subscribe).
+    (Contributed by Richard Townsend, ARM Holdings)
+  Fixed manipulation of machine-specific optimization options.
+    (Contributed by Vicki Pfau)
+  Used memcpy instead of manual pointer arithmetic on Intel SSE2.
+    (Contributed by Samuel Williams)
+  Fixed build errors with MSVC on ARM64.
+    (Contributed by Zhijie Liang)
+  Fixed detection of libm in CMakeLists.
+    (Contributed by Cameron Cawley)
+  Fixed incorrect creation of pkg-config file in CMakeLists.
+    (Contributed by Kyle Bentley)
+  Fixed the CMake build on Windows MSYS by avoiding symlinks.
+  Fixed a build warning on OpenBSD.
+    (Contributed by Theo Buehler)
+  Fixed various typos in comments.
+    (Contributed by "luz.paz")
+  Raised the minimum required CMake version from 3.0.2 to 3.1.
+  Removed yet more of the vestigial support for pre-ANSI C compilers.
+  Removed ancient makefiles for ancient systems that have been broken
+    across all previous libpng-1.6.x versions.
+  Removed the Y2K compliance statement and the export control
+    information.
+  Applied various code style and documentation fixes.
 
-Glenn R-P
+Version 1.6.37 [April 14, 2019]
+  Fixed a use-after-free vulnerability (CVE-2019-7317) in png_image_free.
+  Fixed a memory leak in the ARM NEON implementation of png_do_expand_palette.
+  Fixed a memory leak in pngtest.c.
+  Fixed two vulnerabilities (CVE-2018-14048, CVE-2018-14550) in
+    contrib/pngminus; refactor.
+  Changed the license of contrib/pngminus to MIT; refresh makefile and docs.
+    (Contributed by Willem van Schaik)
+  Fixed a typo in the libpng license v2.
+    (Contributed by Miguel Ojeda)
+  Added makefiles for AddressSanitizer-enabled builds.
+  Cleaned up various makefiles.
+
+Version 1.6.38 [September 14, 2022]
+  Added configurations and scripts for continuous integration.
+  Fixed various errors in the handling of tRNS, hIST and eXIf.
+  Implemented many stability improvements across all platforms.
+  Updated the internal documentation.
+
+Version 1.6.39 [November 20, 2022]
+  Changed the error handler of oversized chunks (i.e. larger than
+    PNG_USER_CHUNK_MALLOC_MAX) from png_chunk_error to png_benign_error.
+  Fixed a buffer overflow error in contrib/tools/pngfix.
+  Fixed a memory leak (CVE-2019-6129) in contrib/tools/pngcp.
+  Disabled the ARM Neon optimizations by default in the CMake file,
+    following the default behavior of the configure script.
+  Allowed configure.ac to work with the trunk version of autoconf.
+  Removed the support for "install" targets from the legacy makefiles;
+    removed the obsolete makefile.cegcc.
+  Cleaned up the code and updated the internal documentation.
+
+Version 1.6.40 [June 21, 2023]
+  Fixed the eXIf chunk multiplicity checks.
+  Fixed a memory leak in pCAL processing.
+  Corrected the validity report about tRNS inside png_get_valid().
+  Fixed various build issues on *BSD, Mac and Windows.
+  Updated the configurations and the scripts for continuous integration.
+  Cleaned up the code, the build scripts, and the documentation.
+
+Version 1.6.41 [January 24, 2024]
+  Added SIMD-optimized code for the LoongArch LSX hardware.
+    (Contributed by GuXiWei, JinBo and ZhangLixia)
+  Fixed the run-time discovery of MIPS MSA hardware.
+    (Contributed by Sui Jingfeng)
+  Fixed an off-by-one error in the function png_do_check_palette_indexes(),
+    which failed to recognize errors that might have existed in the first
+    column of a broken palette-encoded image. This was a benign regression
+    accidentally introduced in libpng-1.6.33. No pixel was harmed.
+    (Contributed by Adam Richter; reviewed by John Bowler)
+  Fixed, improved and modernized the contrib/pngminus programs, i.e.,
+    png2pnm.c and pnm2png.c
+  Removed old and peculiar portability hacks that were meant to silence
+    warnings issued by gcc version 7.1 alone.
+    (Contributed by John Bowler)
+  Fixed and modernized the CMake file, and raised the minimum required
+    CMake version from 3.1 to 3.6.
+    (Contributed by Clinton Ingram, Timothy Lyanguzov, Tyler Kropp, et al.)
+  Allowed the configure script to disable the building of auxiliary tools
+    and tests, thus catching up with the CMake file.
+    (Contributed by Carlo Bramini)
+  Fixed a build issue on Mac.
+    (Contributed by Zixu Wang)
+  Moved the Autoconf macro files to scripts/autoconf.
+  Moved the CMake files (except for the main CMakeLists.txt) to
+    scripts/cmake and moved the list of their contributing authors to
+    scripts/cmake/AUTHORS.md
+  Updated the CI configurations and scripts.
+  Relicensed the CI scripts to the MIT License.
+  Improved the test coverage.
+    (Contributed by John Bowler)
+
+Version 1.6.42 [January 29, 2024]
+  Fixed the implementation of the macro function png_check_sig().
+    This was an API regression, introduced in libpng-1.6.41.
+    (Reported by Matthieu Darbois)
+  Fixed and updated the libpng manual.
+
+Version 1.6.43 [February 23, 2024]
+  Fixed the row width check in png_check_IHDR().
+    This corrected a bug that was specific to the 16-bit platforms,
+    and removed a spurious compiler warning from the 64-bit builds.
+    (Reported by Jacek Caban; fixed by John Bowler)
+  Added eXIf chunk support to the push-mode reader in pngpread.c.
+    (Contributed by Chris Blume)
+  Added contrib/pngexif for the benefit of the users who would like
+    to inspect the content of eXIf chunks.
+  Added contrib/conftest/basic.dfa, a basic build-time configuration.
+    (Contributed by John Bowler)
+  Fixed a preprocessor condition in pngread.c that broke build-time
+    configurations like contrib/conftest/pngcp.dfa.
+    (Contributed by John Bowler)
+  Added CMake build support for LoongArch LSX.
+    (Contributed by GuXiWei)
+  Fixed a CMake build error that occurred under a peculiar state of the
+    dependency tree. This was a regression introduced in libpng-1.6.41.
+    (Contributed by Dan Rosser)
+  Marked the installed libpng headers as system headers in CMake.
+    (Contributed by Benjamin Buch)
+  Updated the build support for RISCOS.
+    (Contributed by Cameron Cawley)
+  Updated the makefiles to allow cross-platform builds to initialize
+    conventional make variables like AR and ARFLAGS.
+  Added various improvements to the CI scripts in areas like version
+    consistency verification and text linting.
+  Added version consistency verification to pngtest.c also.
+
+Version 1.6.44 [September 12, 2024]
+  Hardened calculations in chroma handling to prevent overflows, and
+    relaxed a constraint in cHRM validation to accomodate the standard
+    ACES AP1 set of color primaries.
+    (Contributed by John Bowler)
+  Removed the ASM implementation of ARM Neon optimizations and updated
+    the build accordingly. Only the remaining C implementation shall be
+    used from now on, thus ensuring the support of the PAC/BTI security
+    features on ARM64.
+    (Contributed by Ross Burton and John Bowler)
+  Fixed the pickup of the PNG_HARDWARE_OPTIMIZATIONS option in the
+    CMake build on FreeBSD/amd64. This is an important performance fix
+    on this platform.
+  Applied various fixes and improvements to the CMake build.
+    (Contributed by Eric Riff, Benjamin Buch and Erik Scholz)
+  Added fuzzing targets for the simplified read API.
+    (Contributed by Mikhail Khachayants)
+  Fixed a build error involving pngtest.c under a custom config.
+    This was a regression introduced in a code cleanup in libpng-1.6.43.
+    (Contributed by Ben Wagner)
+  Fixed and improved the config files for AppVeyor CI and Travis CI.
+
+Version 1.6.45 [January 7, 2025]
+  Added support for the cICP chunk.
+    (Contributed by Lucas Chollet and John Bowler)
+  Adjusted and improved various checks in colorspace calculations.
+    (Contributed by John Bowler)
+  Rearranged the write order of colorspace chunks for better conformance
+    with the PNG v3 draft specification.
+    (Contributed by John Bowler)
+  Raised the minimum required CMake version from 3.6 to 3.14.
+  Forked off a development branch for libpng version 1.8.
+
+Version 1.6.46 [January 23, 2025]
+  Added support for the mDCV and cLLI chunks.
+    (Contributed by John Bowler)
+  Fixed a build issue affecting C89 compilers.
+    This was a regression introduced in libpng-1.6.45.
+    (Contributed by John Bowler)
+  Added makefile.c89, specifically for testing C89 compilers.
+  Cleaned up contrib/pngminus: corrected an old typo, removed an old
+    workaround, and updated the CMake file.
+
+Version 1.6.47 [February 18, 2025]
+  Modified the behaviour of colorspace chunks in order to adhere
+    to the new precedence rules formulated in the latest draft of
+    the PNG Specification.
+    (Contributed by John Bowler)
+  Fixed a latent bug in `png_write_iCCP`.
+    This would have been a read-beyond-end-of-malloc vulnerability,
+    introduced early in the libpng-1.6.0 development, yet (fortunately!)
+    it was inaccessible before the above-mentioned modification of the
+    colorspace precedence rules, due to pre-existing colorspace checks.
+    (Reported by Bob Friesenhahn; fixed by John Bowler)
+
+Version 1.6.48 [April 30, 2025]
+  Fixed the floating-point version of the mDCv setter `png_set_mDCv`.
+    (Reported by Mohit Bakshi; fixed by John Bowler)
+  Added #error directives to discourage the inclusion of private
+    libpng implementation header files in PNG-supporting applications.
+  Added the CMake build option `PNG_LIBCONF_HEADER`, to be used as an
+    alternative to `DFA_XTRA`.
+  Removed the Travis CI configuration files, with heartfelt thanks for
+    their generous support of our project over the past five years!
+
+Version 1.6.49 [June 12, 2025]
+  Added SIMD-optimized code for the RISC-V Vector Extension (RVV).
+    (Contributed by Manfred Schlaegl, Dragos Tiselice and Filip Wasil)
+  Added various fixes and improvements to the build scripts and to
+    the sample code.
+
+Version 1.6.50 [July 1, 2025]
+  Improved the detection of the RVV Extension on the RISC-V platform.
+    (Contributed by Filip Wasil)
+  Replaced inline ASM with C intrinsics in the RVV code.
+    (Contributed by Filip Wasil)
+  Fixed a decoder defect in which unknown chunks trailing IDAT, set
+    to go through the unknown chunk handler, incorrectly triggered
+    out-of-place IEND errors.
+    (Contributed by John Bowler)
+  Fixed the CMake file for cross-platform builds that require `libm`.
+
+Version 1.6.51 [TODO]
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net.
+Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe.

INSTALL

@@ -1,4 +1,3 @@
-
     Installing libpng
 
 Contents
@@ -128,16 +127,18 @@ Your directory structure should look like this:
           README
           *.h, *.c  => libpng source files
           CMakeLists.txt    =>  "cmake" script
+          ci
+             ci_*.sh
           configuration files:
              configure.ac, configure, Makefile.am, Makefile.in,
              autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
              libpng-config.in, aclocal.m4, config.h.in, config.sub,
-             depcomp, install-sh, mkinstalldirs, test-pngtest.sh
+             depcomp, install-sh, mkinstalldirs, test-pngtest.sh, etc.
           contrib
              arm-neon, conftest, examples, gregbook, libtests, pngminim,
-             pngminus, pngsuite, tools, visupng
+             pngminus, pngsuite, tools, visupng, riscv-rvv
           projects
-             cbuilder5, owatcom, visualc71, vstudio, xcode
+             owatcom, visualc71, vstudio
           scripts
              makefile.*
              *.def (module definition files)
@@ -145,7 +146,7 @@ Your directory structure should look like this:
           pngtest.png
           etc.
       zlib
-          README, *.h, *.c contrib, etc.
+          README, *.h, *.c, contrib, etc.
 
 If the line endings in the files look funny, you may wish to get the other
 distribution of libpng.  It is available in both tar.gz (UNIX style line
@@ -153,28 +154,27 @@ endings) and zip (DOS style line endings) formats.
 
 VI. Building with project files
 
-If you are building libpng with MSVC, you can enter the
+If you are building libpng with Microsoft Visual Studio, you can enter
-libpng projects\visualc71 or vstudio directory and follow the instructions
+the directory projects\visualc71 or projects\vstudio and follow the
-in README.txt.
+instructions in README.txt.
 
-Otherwise enter the zlib directory and follow the instructions in zlib/README,
+Otherwise, enter the zlib directory and follow the instructions in
-then come back here and run "configure" or choose the appropriate
+zlib/README, then come back here and run "configure" or choose the
-makefile.sys in the scripts directory.
+appropriate makefile in the scripts directory.
 
 VII. Building with makefiles
 
 Copy the file (or files) that you need from the
 scripts directory into this directory, for example
 
-MSDOS example:
-
-    copy scripts\makefile.msc makefile
-    copy scripts\pnglibconf.h.prebuilt pnglibconf.h
-
 UNIX example:
 
-    cp scripts/makefile.std makefile
+    cp scripts/makefile.std Makefile
-    cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+    make
+
+Windows example:
+
+    nmake -f scripts\makefile.vcwin32
 
 Read the makefile to see if you need to change any source or
 target directories to match your preferences.
@@ -191,36 +191,33 @@ test.  For more confidence, you can run another test by typing
 Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
 your output with the result shown in contrib/pngsuite/README.
 
-Most of the makefiles will allow you to run "make install" to
+Most of the makefiles used to allow you to run "make install" to put
-put the library in its final resting place (if you want to
+the library in its final resting place, but that feature is no longer
-do that, run "make install" in the zlib directory first if necessary).
+supported.  The only tested and supported manners to install libpng are
-Some also allow you to run "make test-installed" after you have
+the conventional build and install procedures driven by the configure
-run "make install".
+script or by the CMake file.
 
-VIII. Configuring libpng for 16-bit platforms
+VIII. Configuring for DOS and other 16-bit platforms
 
-You will want to look into zconf.h to tell zlib (and thus libpng) that
+Officially, the support for 16-bit platforms has been removed.
-it cannot allocate more than 64K at a time.  Even if you can, the memory
-won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
-
-IX. Configuring for DOS
 
 For DOS users who only have access to the lower 640K, you will
 have to limit zlib's memory usage via a png_set_compression_mem_level()
 call.  See zlib.h or zconf.h in the zlib library for more information.
 
-X. Configuring for Medium Model
+You may be or may not be in luck if you target the "large" memory model,
+but all the smaller models ("small", "compact" and "medium") are known
+to be unworkable.  For DOS users who have access beyond the lower 640K,
+a "flat" 32-bit DOS model (such as DJGPP) is strongly recommended.
 
-Libpng's support for medium model has been tested on most of the popular
+For DOS users who only have access to the lower 640K, you will have to
-compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+limit zlib's memory usage via a png_set_compression_mem_level() call.
-defined, and FAR gets defined to far in pngconf.h, and you should be
+You will also have to look into zconf.h to tell zlib (and thus libpng)
-all set.  Everything in the library (except for zlib's structure) is
+that it cannot allocate more than 64K at a time.  Even if you can, the
-expecting far data.  You must use the typedefs with the p or pp on
+memory won't be accessible.  Therefore, you should limit zlib and libpng
-the end for pointers (or at least look at them and be careful).  Make
+to 64K by defining MAXSEG_64K.
-note that the rows of data are defined as png_bytepp, which is
-an "unsigned char far * far *".
 
-XI. Prepending a prefix to exported symbols
+IX. Prepending a prefix to exported symbols
 
 Starting with libpng-1.6.0, you can configure libpng (when using the
 "configure" script) to prefix all exported symbols by means of the
@@ -231,7 +228,7 @@ identifier).  This creates a set of macros in pnglibconf.h, so this is
 transparent to applications; their function calls get transformed by
 the macros to use the modified names.
 
-XII. Configuring for compiler xxx:
+X. Configuring for compiler xxx:
 
 All includes for libpng are in pngconf.h.  If you need to add, change
 or delete an include, this is the place to do it.
@@ -243,7 +240,7 @@ As of libpng-1.5.0, pngpriv.h also includes three other private header
 files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
 that previously appeared in the public headers.
 
-XIII. Removing unwanted object code
+XI. Removing unwanted object code
 
 There are a bunch of #define's in pngconf.h that control what parts of
 libpng are compiled.  All the defines end in _SUPPORTED.  If you are
@@ -282,7 +279,7 @@ 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
+XII. 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
@@ -292,6 +289,7 @@ such as one of
    --enable-mips-msa=yes
    --enable-intel-sse=yes
    --enable-powerpc-vsx=yes
+   --enable-riscv-rvv=yes
 
 or enable them all at once with
 
@@ -304,6 +302,7 @@ or more of
    CPPFLAGS += "-DPNG_MIPS_MSA"
    CPPFLAGS += "-DPNG_INTEL_SSE"
    CPPFLAGS += "-DPNG_POWERPC_VSX"
+   CPPFLAGS += "-DPNG_RISCV_RVV"
 
 See for example scripts/makefile.linux-opt
 
@@ -320,19 +319,21 @@ 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"
+   -DPNG_INTEL_SSE_OPT=0, -DPNG_POWERPC_VSX_OPT=0,
+   -DPNG_RISCV_RVV_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
+            -DPNG_MIPS_MSA=no -DPNG_POWERPC_VSX=no \
+            -DPNG_RISCV_RVV=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
+XIII. 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 +424,7 @@ $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
+XIV. 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 +442,7 @@ 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
+XV. Common linking failures
 
 If your application fails to find libpng or zlib entries while linking:
 
@@ -453,12 +454,13 @@ 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:
+XVI. Other sources of information about libpng:
 
 Further information can be found in the README and libpng-manual.txt
 files, in the individual makefiles, in png.h, and the manual pages
 libpng.3 and png.5.
 
+Copyright (c) 2022 Cosmin Truta
 Copyright (c) 1998-2002,2006-2016 Glenn Randers-Pehrson
 This document is released under the libpng license.
 For conditions of distribution and use, see the disclaimer

LICENSE

@@ -1,53 +1,82 @@
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
+=========================================
 
-This copy of the libpng notices is provided for your convenience.  In case of
+PNG Reference Library License version 2
-any discrepancy between this copy and the notices in the file png.h that is
+---------------------------------------
-included in the libpng distribution, the latter shall prevail.
 
-COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ * Copyright (c) 1995-2025 The PNG Reference Library Authors.
+ * Copyright (c) 2018-2025 Cosmin Truta.
+ * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson.
+ * Copyright (c) 1996-1997 Andreas Dilger.
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 
-If you modify libpng you may insert additional notices immediately following
+The software is supplied "as is", without warranty of any kind,
-this sentence.
+express or implied, including, without limitation, the warranties
+of merchantability, fitness for a particular purpose, title, and
+non-infringement.  In no event shall the Copyright owners, or
+anyone distributing the software, be liable for any damages or
+other liability, whether in contract, tort or otherwise, arising
+from, out of, or in connection with the software, or the use or
+other dealings in the software, even if advised of the possibility
+of such damage.
 
-This code is released under the libpng license.
+Permission is hereby granted to use, copy, modify, and distribute
+this software, or portions hereof, for any purpose, without fee,
+subject to the following restrictions:
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.35, July 15, 2018 are
+ 1. The origin of this software must not be misrepresented; you
+    must not claim that you wrote the original software.  If you
+    use this software in a product, an acknowledgment in the product
+    documentation would be appreciated, but is not required.
+
+ 2. Altered source versions must be plainly marked as such, and must
+    not be misrepresented as being the original software.
+
+ 3. This Copyright notice may not be removed or altered from any
+    source or altered source distribution.
+
+
+PNG Reference Library License version 1 (for libpng 0.5 through 1.6.35)
+-----------------------------------------------------------------------
+
+libpng versions 1.0.7, July 1, 2000, through 1.6.35, July 15, 2018 are
 Copyright (c) 2000-2002, 2004, 2006-2018 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:
 
-   Simon-Pierre Cadieux
+    Simon-Pierre Cadieux
-   Eric S. Raymond
+    Eric S. Raymond
-   Mans Rullgard
+    Mans Rullgard
-   Cosmin Truta
+    Cosmin Truta
-   Gilles Vollant
+    Gilles Vollant
-   James Yu
+    James Yu
-   Mandar Sahastrabuddhe
+    Mandar Sahastrabuddhe
-   Google Inc.
+    Google Inc.
-   Vadim Barkov
+    Vadim Barkov
 
 and with the following additions to the disclaimer:
 
-   There is no warranty against interference with your enjoyment of the
+    There is no warranty against interference with your enjoyment of
-   library or against infringement.  There is no warranty that our
+    the library or against infringement.  There is no warranty that our
-   efforts or the library will fulfill any of your particular purposes
+    efforts or the library will fulfill any of your particular purposes
-   or needs.  This library is provided with all faults, and the entire
+    or needs.  This library is provided with all faults, and the entire
-   risk of satisfactory quality, performance, accuracy, and effort is with
+    risk of satisfactory quality, performance, accuracy, and effort is
-   the user.
+    with the user.
 
 Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
+files that are distributed with libpng have other copyright owners, and
 are released under other open source licenses.
 
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
-license as libpng-0.96, with the following individuals added to the list
+license as libpng-0.96, with the following individuals added to the
-of Contributing Authors:
+list of Contributing Authors:
 
-   Tom Lane
+    Tom Lane
-   Glenn Randers-Pehrson
+    Glenn Randers-Pehrson
-   Willem van Schaik
+    Willem van Schaik
 
 libpng versions 0.89, June 1996, through 0.96, May 1997, are
 Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
@@ -55,14 +84,14 @@ and are distributed according to the same disclaimer and license as
 libpng-0.88, with the following individuals added to the list of
 Contributing Authors:
 
-   John Bowler
+    John Bowler
-   Kevin Bracey
+    Kevin Bracey
-   Sam Bushell
+    Sam Bushell
-   Magnus Holmgren
+    Magnus Holmgren
-   Greg Roelofs
+    Greg Roelofs
-   Tom Tanner
+    Tom Tanner
 
-Some files in the "scripts" directory have other copyright owners
+Some files in the "scripts" directory have other copyright owners,
 but are released under this license.
 
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
@@ -71,63 +100,35 @@ Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 For the purposes of this copyright and license, "Contributing Authors"
 is defined as the following set of individuals:
 
-   Andreas Dilger
+    Andreas Dilger
-   Dave Martindale
+    Dave Martindale
-   Guy Eric Schalnat
+    Guy Eric Schalnat
-   Paul Schmidt
+    Paul Schmidt
-   Tim Wegner
+    Tim Wegner
 
-The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+The PNG Reference Library is supplied "AS IS".  The Contributing
-and Group 42, Inc. disclaim all warranties, expressed or implied,
+Authors and Group 42, Inc. disclaim all warranties, expressed or
-including, without limitation, the warranties of merchantability and of
+implied, including, without limitation, the warranties of
-fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+merchantability and of fitness for any purpose.  The Contributing
-assume no liability for direct, indirect, incidental, special, exemplary,
+Authors and Group 42, Inc. assume no liability for direct, indirect,
-or consequential damages, which may result from the use of the PNG
+incidental, special, exemplary, or consequential damages, which may
-Reference Library, even if advised of the possibility of such damage.
+result from the use of the PNG Reference Library, even if advised of
+the possibility of such damage.
 
 Permission is hereby granted to use, copy, modify, and distribute this
 source code, or portions hereof, for any purpose, without fee, subject
 to the following restrictions:
 
-  1. The origin of this source code must not be misrepresented.
+ 1. The origin of this source code must not be misrepresented.
 
-  2. Altered versions must be plainly marked as such and must not
+ 2. Altered versions must be plainly marked as such and must not
-     be misrepresented as being the original source.
+    be misrepresented as being the original source.
 
-  3. This Copyright notice may not be removed or altered from any
+ 3. This Copyright notice may not be removed or altered from any
-     source or altered source distribution.
+    source or altered source distribution.
 
-The Contributing Authors and Group 42, Inc. specifically permit, without
+The Contributing Authors and Group 42, Inc. specifically permit,
-fee, and encourage the use of this source code as a component to
+without fee, and encourage the use of this source code as a component
-supporting the PNG file format in commercial products.  If you use this
+to supporting the PNG file format in commercial products.  If you use
-source code in a product, acknowledgment is not required but would be
+this source code in a product, acknowledgment is not required but would
-appreciated.
+be appreciated.
-
-END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
-
-TRADEMARK:
-
-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction.  However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
-
-OSI CERTIFICATION:
-
-Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
-a certification mark of the Open Source Initiative. OSI has not addressed
-the additional disclaimers inserted at version 1.0.7.
-
-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
-Glenn Randers-Pehrson
-glennrp at users.sourceforge.net
-July 15, 2018

Makefile.am

@@ -1,7 +1,7 @@
 # Makefile.am, the source file for Makefile.in (and hence Makefile), is
 #
+# Copyright (c) 2018-2025 Cosmin Truta
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
 #
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
@@ -9,16 +9,24 @@
 
 PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
 
-ACLOCAL_AMFLAGS = -I scripts
+ACLOCAL_AMFLAGS = -I scripts/autoconf
 
 # test programs - run on make check, make distcheck
+if ENABLE_TESTS
 check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage pngcp
 if HAVE_CLOCK_GETTIME
 check_PROGRAMS += timepng
 endif
+else
+check_PROGRAMS=
+endif
 
 # Utilities - installed
+if ENABLE_TOOLS
 bin_PROGRAMS= pngfix png-fix-itxt
+else
+bin_PROGRAMS=
+endif
 
 # This ensures that pnglibconf.h gets built at the start of 'make all' or
 # 'make check', but it does not add dependencies to the individual programs,
@@ -30,6 +38,7 @@ bin_PROGRAMS= pngfix png-fix-itxt
 # always wrong and always very confusing.
 BUILT_SOURCES = pnglibconf.h
 
+if ENABLE_TESTS
 pngtest_SOURCES = pngtest.c
 pngtest_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 
@@ -48,19 +57,22 @@ pngimage_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 timepng_SOURCES = contrib/libtests/timepng.c
 timepng_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 
+pngcp_SOURCES = contrib/tools/pngcp.c
+pngcp_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+endif
+
+if ENABLE_TOOLS
 pngfix_SOURCES = contrib/tools/pngfix.c
 pngfix_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 
 png_fix_itxt_SOURCES = contrib/tools/png-fix-itxt.c
-
+endif
-pngcp_SOURCES = contrib/tools/pngcp.c
-pngcp_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
 
 # Generally these are single line shell scripts to run a test with a particular
 # set of parameters:
+if ENABLE_TESTS
 TESTS =\
-   tests/pngtest\
+   tests/pngtest-all\
-   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\
@@ -76,6 +88,7 @@ TESTS =\
    tests/pngunknown-discard tests/pngunknown-if-safe tests/pngunknown-sAPI\
    tests/pngunknown-sTER tests/pngunknown-save tests/pngunknown-vpAg\
    tests/pngimage-quick tests/pngimage-full
+endif
 
 # man pages
 dist_man_MANS= libpng.3 libpngpf.3 png.5
@@ -95,7 +108,8 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
 
 if PNG_ARM_NEON
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
-	arm/filter_neon.S arm/filter_neon_intrinsics.c
+	arm/filter_neon_intrinsics.c \
+	arm/palette_neon_intrinsics.c
 endif
 
 if PNG_MIPS_MSA
@@ -103,6 +117,13 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
 	mips/filter_msa_intrinsics.c
 endif
 
+if PNG_MIPS_MMI
+if !PNG_MIPS_MSA
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c
+endif
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/filter_mmi_inline_assembly.c
+endif
+
 if PNG_INTEL_SSE
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += intel/intel_init.c\
 	intel/filter_sse2_intrinsics.c
@@ -113,6 +134,22 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += powerpc/powerpc_init.c\
         powerpc/filter_vsx_intrinsics.c
 endif
 
+if PNG_RISCV_RVV
+noinst_LTLIBRARIES= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv_la_SOURCES = riscv/riscv_init.c\
+        riscv/filter_rvv_intrinsics.c
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv_la_CFLAGS = -march=rv64gv
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LIBADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+endif
+
+if PNG_LOONGARCH_LSX
+noinst_LTLIBRARIES= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx_la_SOURCES = loongarch/loongarch_lsx_init.c\
+	loongarch/filter_lsx_intrinsics.c
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx_la_CFLAGS = -mlsx
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LIBADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+endif
+
 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
 
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
@@ -133,6 +170,14 @@ else
   libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES = libpng.sym
 endif
 
+if PNG_RISCV_RVV
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES += libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@rvv.la
+endif
+
+if PNG_LOONGARCH_LSX
+  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES += libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@lsx.la
+endif
+
 #distribute headers in /usr/include/libpng/*
 pkgincludedir= $(includedir)/$(PNGLIB_BASENAME)
 pkginclude_HEADERS= png.h pngconf.h
@@ -147,9 +192,9 @@ pkgconfig_DATA = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc
 # from those directories being included.  This only works if the configure is
 # not done in the source directory!
 EXTRA_DIST= \
-	ANNOUNCE CHANGES INSTALL LICENSE README TODO \
+	ANNOUNCE AUTHORS CHANGES INSTALL LICENSE README TODO TRADEMARK \
 	pngtest.png pngbar.png pngnow.png pngbar.jpg autogen.sh \
-	${srcdir}/contrib ${srcdir}/projects ${srcdir}/scripts \
+	${srcdir}/ci ${srcdir}/contrib ${srcdir}/projects ${srcdir}/scripts \
 	$(TESTS) $(XFAIL_TESTS) tests/pngstest \
 	CMakeLists.txt example.c libpng-manual.txt
 
@@ -165,7 +210,7 @@ MAINTAINERCLEANFILES = Makefile.in aclocal.m4 config.guess config.h.in \
 config.sub configure depcomp install-sh ltmain.sh missing
 
 # PNG_COPTS give extra options for the C compiler to be used on all compilation
-# steps (unless targe_CFLAGS is specified; that will take precedence over
+# steps (unless target_CFLAGS is specified; that will take precedence over
 # AM_CFLAGS)
 PNG_COPTS = @PNG_COPTS@
 AM_CFLAGS = ${PNG_COPTS}

README

@@ -1,56 +1,88 @@
-README for libpng version 1.6.35 - July 15, 2018 (shared library 16.0)
+README for libpng version 1.6.51.git
-See the note about version numbers near the top of png.h
+====================================
 
-See INSTALL for instructions on how to install libpng.
+See the note about version numbers near the top of `png.h`.
+See `INSTALL` for instructions on how to install libpng.
 
-Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
+Libpng comes in several distribution formats.  Get `libpng-*.tar.gz`
-libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
+or `libpng-*.tar.xz` if you want UNIX-style line endings in the text
-or lpng*.7z or lpng*.zip if you want DOS-style line endings.
+files, or `lpng*.7z` or `lpng*.zip` if you want DOS-style line endings.
 
-Version 0.89 was the first official release of libpng.  Don't let the
+For a detailed description on using libpng, read `libpng-manual.txt`.
-fact that it's the first release fool you.  The libpng library has been in
+For examples of libpng in a program, see `example.c` and `pngtest.c`.
-extensive use and testing since mid-1995.  By late 1997 it had
+For usage information and restrictions (what little they are) on libpng,
-finally gotten to the stage where there hadn't been significant
+see `png.h`.  For a description on using zlib (the compression library
-changes to the API in some time, and people have a bad feeling about
+used by libpng) and zlib's restrictions, see `zlib.h`.
-libraries with versions < 1.0.  Version 1.0.0 was released in
-March 1998.
 
-****
+You should use zlib 1.0.4 or later to run this, but it _may_ work with
-Note that some of the changes to the png_info structure render this
+versions as old as zlib 0.95.  Even so, there are bugs in older zlib
+versions which can cause the output of invalid compression streams for
+some images.
+
+You should also note that zlib is a compression library that is useful
+for more things than just PNG files.  You can use zlib as a drop-in
+replacement for `fread()` and `fwrite()`, if you are so inclined.
+
+zlib should be available at the same place that libpng is, or at
+https://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 .
+
+This code is currently being archived at https://libpng.sourceforge.io
+in the download area, and at http://libpng.download/src .
+
+This release, based in a large way on Glenn's, Guy's and Andreas'
+earlier work, was created and will be supported by myself and the PNG
+development group.
+
+Send comments, corrections and commendations to `png-mng-implement`
+at `lists.sourceforge.net`.  (Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe.)
+
+Send general questions about the PNG specification to `png-mng-misc`
+at `lists.sourceforge.net`.  (Subscription is required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-misc
+to subscribe.)
+
+Historical notes
+----------------
+
+The libpng library has been in extensive use and testing since mid-1995.
+Version 0.89, published a year later, was the first official release.
+By late 1997, it had finally gotten to the stage where there hadn't
+been significant changes to the API in some time, and people have a bad
+feeling about libraries with versions below 1.0.  Version 1.0.0 was
+released in March 1998.
+
+Note that some of the changes to the `png_info` structure render this
 version of the library binary incompatible with libpng-0.89 or
 earlier versions if you are using a shared library.  The type of the
-"filler" parameter for png_set_filler() has changed from png_byte to
+`filler` parameter for `png_set_filler()` has changed from `png_byte`
-png_uint_32, which will affect shared-library applications that use
+to `png_uint_32`, which will affect shared-library applications that
-this function.
+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 the `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
+access to `info_ptr`.  These functions are the `png_set_<chunk>` and
-png_get_<chunk> functions.  These functions should be used when
+`png_get_<chunk>` functions.  These functions should be used when
-accessing/storing the info_struct data, rather than manipulating it
+accessing/storing the `info_struct` data, rather than manipulating it
 directly, to avoid such problems in the future.
 
 It is important to note that the APIs did not make current programs
 that access the info struct directly incompatible with the new
 library, through libpng-1.2.x.  In libpng-1.4.x, which was meant to
-be a transitional release, members of the png_struct and the
+be a transitional release, members of the `png_struct` and the
-info_struct can still be accessed, but the compiler will issue a
+`info_struct` can still be accessed, but the compiler will issue a
 warning about deprecated usage.  Since libpng-1.5.0, direct access
 to these structs is not allowed, and the definitions of the structs
-reside in private pngstruct.h and pnginfo.h header files that are not
+reside in private `pngstruct.h` and `pnginfo.h` header files that are
-accessible to applications.  It is strongly suggested that new
+not accessible to applications.  It is strongly suggested that new
-programs use the new APIs (as shown in example.c and pngtest.c), and
+programs use the new APIs (as shown in `example.c` and `pngtest.c`),
-older programs be converted to the new format, to facilitate upgrades
+and older programs be converted to the new format, to facilitate
-in the future.
+upgrades in the future.
-****
-
-Additions since 0.90 include the ability to compile libpng as a
-Windows DLL, and new APIs for accessing data in the info struct.
-Experimental functions include the ability to set weighting and cost
-factors for row filter selection, direct reads of integers from buffers
-on big-endian processors that support misaligned data access, faster
-methods of doing alpha composition, and more accurate 16->8 bit color
-conversion.
 
 The additions since 0.89 include the ability to read from a PNG stream
 which has had some (or all) of the signature bytes read by the calling
@@ -60,163 +92,93 @@ the library action on the detection of chunk CRC errors.  It is possible
 to set different actions based on whether the CRC error occurred in a
 critical or an ancillary chunk.
 
-The changes made to the library, and bugs fixed are based on discussions
+The additions since 0.90 include the ability to compile libpng as a
-on the PNG-implement mailing list and not on material submitted
+Windows DLL, and new APIs for accessing data in the `info_struct`.
-privately to Guy, Andreas, or Glenn.  They will forward any good
+Experimental functions included the ability to set weighting and cost
-suggestions to the list.
+factors for row filter selection, direct reads of integers from buffers
+on big-endian processors that support misaligned data access, faster
+methods of doing alpha composition, and more accurate 16-to-8 bit color
+conversion.  Some of these experimental functions, such as the weighted
+filter heuristics, have since been removed.
 
-For a detailed description on using libpng, read libpng-manual.txt.  For
+Files included in this distribution
-examples of libpng in a program, see example.c and pngtest.c.  For usage
+-----------------------------------
-information and restrictions (what little they are) on libpng, see
-png.h.  For a description on using zlib (the compression library used by
-libpng) and zlib's restrictions, see zlib.h
 
-I have included a general makefile, as well as several machine and
+    ANNOUNCE      =>  Announcement of this version, with recent changes
-compiler specific ones, but you may have to modify one for your own needs.
+    AUTHORS       =>  List of contributing authors
+    CHANGES       =>  Description of changes between libpng versions
+    INSTALL       =>  Instructions to install libpng
+    LICENSE       =>  License to use and redistribute libpng
+    README        =>  This file
+    TODO          =>  Things not implemented in the current library
+    TRADEMARK     =>  Trademark information
+    example.c     =>  Example code for using libpng functions
+    libpng.3      =>  Manual page for libpng (includes libpng-manual.txt)
+    libpng-manual.txt  =>  Description of libpng and its functions
+    libpngpf.3    =>  Manual page for libpng's private functions (deprecated)
+    png.5         =>  Manual page for the PNG format
+    png.c         =>  Basic interface functions common to library
+    png.h         =>  Library function and interface declarations (public)
+    pngpriv.h     =>  Library function and interface declarations (private)
+    pngconf.h     =>  System specific library configuration (public)
+    pngstruct.h   =>  png_struct declaration (private)
+    pnginfo.h     =>  png_info struct declaration (private)
+    pngdebug.h    =>  debugging macros (private)
+    pngerror.c    =>  Error/warning message I/O functions
+    pngget.c      =>  Functions for retrieving info from struct
+    pngmem.c      =>  Memory handling functions
+    pngbar.png    =>  PNG logo, 88x31
+    pngnow.png    =>  PNG logo, 98x31
+    pngpread.c    =>  Progressive reading functions
+    pngread.c     =>  Read data/helper high-level functions
+    pngrio.c      =>  Lowest-level data read I/O functions
+    pngrtran.c    =>  Read data transformation functions
+    pngrutil.c    =>  Read data utility functions
+    pngset.c      =>  Functions for storing data into the info_struct
+    pngtest.c     =>  Library test program
+    pngtest.png   =>  Library test sample image
+    pngtrans.c    =>  Common data transformation functions
+    pngwio.c      =>  Lowest-level write I/O functions
+    pngwrite.c    =>  High-level write functions
+    pngwtran.c    =>  Write data transformations
+    pngwutil.c    =>  Write utility functions
+    arm/          =>  Optimized code for ARM Neon
+    intel/        =>  Optimized code for INTEL SSE2
+    loongarch/    =>  Optimized code for LoongArch LSX
+    mips/         =>  Optimized code for MIPS MSA and MIPS MMI
+    powerpc/      =>  Optimized code for PowerPC VSX
+    riscv/        =>  Optimized code for the RISC-V platform
+    ci/           =>  Scripts for continuous integration
+    contrib/      =>  External contributions
+        arm-neon/     =>  Optimized code for the ARM-NEON platform
+        mips-msa/     =>  Optimized code for the MIPS-MSA platform
+        powerpc-vsx/  =>  Optimized code for the POWERPC-VSX platform
+        examples/     =>  Examples of libpng usage
+        gregbook/     =>  Source code for PNG reading and writing, from
+                          "PNG: The Definitive Guide" by Greg Roelofs,
+                          O'Reilly, 1999
+        libtests/     =>  Test programs
+        pngexif/      =>  Program to inspect the EXIF information in PNG files
+        pngminim/     =>  Minimal decoder, encoder, and progressive decoder
+                          programs demonstrating the use of pngusr.dfa
+        pngminus/     =>  Simple pnm2png and png2pnm programs
+        pngsuite/     =>  Test images
+        riscv-rvv/    =>  Optimized code for the RISC-V Vector platform
+        testpngs/     =>  Test images
+        tools/        =>  Various tools
+        visupng/      =>  VisualPng, a Windows viewer for PNG images
+    projects/     =>  Project files and workspaces for various IDEs
+        owatcom/      =>  OpenWatcom project
+        visualc71/    =>  Microsoft Visual C++ 7.1 workspace
+        vstudio/      =>  Microsoft Visual Studio workspace
+    scripts/      =>  Scripts and makefiles for building libpng
+                      (see scripts/README.txt for the complete list)
+    tests/        =>  Test scripts
 
-You should use zlib 1.0.4 or later to run this, but it MAY work with
+Good luck, and happy coding!
-versions as old as zlib 0.95.  Even so, there are bugs in older zlib
-versions which can cause the output of invalid compression streams for
-some images.  You will definitely need zlib 1.0.4 or later if you are
-taking advantage of the MS-DOS "far" structure allocation for the small
-and medium memory models.  You should also note that zlib is a
-compression library that is useful for more things than just PNG files.
-You can use zlib as a drop-in replacement for fread() and fwrite() if
-you are so inclined.
 
-zlib should be available at the same place that libpng is, or at zlib.net.
+ * Cosmin Truta (current maintainer, since 2018)
-
+ * Glenn Randers-Pehrson (former maintainer, 1998-2018)
-You may also want a copy of the PNG specification.  It is available
+ * Andreas Eric Dilger (former maintainer, 1996-1997)
-as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
+ * Guy Eric Schalnat (original author and former maintainer, 1995-1996)
-these at http://www.libpng.org/pub/png/pngdocs.html .
+   (formerly of Group 42, Inc.)
-
-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.
-
-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
-controls or International Traffic in Arms Regulations (ITAR) because it
-is open source, publicly available software, that does not contain any
-encryption software.  See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
-
-If you have any code changes, requests, problems, etc., please e-mail
-them to me.  Also, I'd appreciate any make files or project files,
-and any modifications you needed to make to get libpng to compile,
-along with a #define variable to tell what compiler/system you are on.
-If you needed to add transformations to libpng, or wish libpng would
-provide the image in a different way, drop me a note (and code, if
-possible), so I can consider supporting the transformation.
-Finally, if you get any warning messages when compiling libpng
-(note: not zlib), and they are easy to fix, I'd appreciate the
-fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
-
-This release was created and will be supported by myself (of course
-based in a large way on Guy's and Andreas' earlier work), and the PNG
-development group.
-
-Send comments/corrections/commendations to png-mng-implement at
-lists.sourceforge.net (subscription required; visit
-https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe).
-
-You can't reach Guy, the original libpng author, at the addresses
-given in previous versions of this document.  He and Andreas will
-read mail addressed to the png-implement list, however.
-
-Please do not send general questions about PNG.  Send them to
-png-mng-misc at lists.sf.net (subscription required; visit
-https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
-subscribe).  If you have a question about something
-in the PNG specification that is related to using libpng, send it
-to me.  Send me any questions that start with "I was using libpng,
-and ...".  If in doubt, send questions to me.  I'll bounce them
-to others, if necessary.
-
-Please do not send suggestions on how to change PNG.  We have
-been discussing PNG for twenty years now, and it is official and
-finished.  If you have suggestions for libpng, however, I'll
-gladly listen.  Even if your suggestion is not used immediately,
-it may be used later.
-
-Files in this distribution:
-
-      ANNOUNCE      =>  Announcement of this version, with recent changes
-      CHANGES       =>  Description of changes between libpng versions
-      KNOWNBUG      =>  List of known bugs and deficiencies
-      LICENSE       =>  License to use and redistribute libpng
-      README        =>  This file
-      TODO          =>  Things not implemented in the current library
-      Y2KINFO       =>  Statement of Y2K compliance
-      example.c     =>  Example code for using libpng functions
-      libpng.3      =>  manual page for libpng (includes libpng-manual.txt)
-      libpng-manual.txt  =>  Description of libpng and its functions
-      libpngpf.3    =>  manual page for libpng's private functions
-      png.5         =>  manual page for the PNG format
-      png.c         =>  Basic interface functions common to library
-      png.h         =>  Library function and interface declarations (public)
-      pngpriv.h     =>  Library function and interface declarations (private)
-      pngconf.h     =>  System specific library configuration (public)
-      pngstruct.h   =>  png_struct declaration (private)
-      pnginfo.h     =>  png_info struct declaration (private)
-      pngdebug.h    =>  debugging macros (private)
-      pngerror.c    =>  Error/warning message I/O functions
-      pngget.c      =>  Functions for retrieving info from struct
-      pngmem.c      =>  Memory handling functions
-      pngbar.png    =>  PNG logo, 88x31
-      pngnow.png    =>  PNG logo, 98x31
-      pngpread.c    =>  Progressive reading functions
-      pngread.c     =>  Read data/helper high-level functions
-      pngrio.c      =>  Lowest-level data read I/O functions
-      pngrtran.c    =>  Read data transformation functions
-      pngrutil.c    =>  Read data utility functions
-      pngset.c      =>  Functions for storing data into the info_struct
-      pngtest.c     =>  Library test program
-      pngtest.png   =>  Library test sample image
-      pngtrans.c    =>  Common data transformation functions
-      pngwio.c      =>  Lowest-level write I/O functions
-      pngwrite.c    =>  High-level write functions
-      pngwtran.c    =>  Write data transformations
-      pngwutil.c    =>  Write utility functions
-      arm           =>  Contains optimized code for the ARM platform
-      powerpc       =>  Contains optimized code for the PowerPC platform
-      contrib       =>  Contributions
-       arm-neon         =>  Optimized code for ARM-NEON platform
-       powerpc-vsx      =>  Optimized code for POWERPC-VSX platform
-       examples         =>  Example programs
-       gregbook         =>  source code for PNG reading and writing, from
-                            Greg Roelofs' "PNG: The Definitive Guide",
-                            O'Reilly, 1999
-       libtests         =>  Test programs
-       mips-msa         =>  Optimized code for MIPS-MSA platform
-       pngminim         =>  Minimal decoder, encoder, and progressive decoder
-                            programs demonstrating use of pngusr.dfa
-       pngminus         =>  Simple pnm2png and png2pnm programs
-       pngsuite         =>  Test images
-       testpngs
-       tools            =>  Various tools
-       visupng          =>  Contains a MSVC workspace for VisualPng
-      intel             =>  Optimized code for INTEL-SSE2 platform
-      mips              =>  Optimized code for MIPS platform
-      projects      =>  Contains project files and workspaces for
-                        building a DLL
-       owatcom          =>  Contains a WATCOM project for building libpng
-       visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
-                            workspace for building libpng and zlib
-       vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
-                            workspace for building libpng and zlib
-      scripts       =>  Directory containing scripts for building libpng:
-                            (see scripts/README.txt for the list of scripts)
-
-Good luck, and happy coding.
-
--Glenn Randers-Pehrson (current maintainer, since 1998)
- Internet: glennrp at users.sourceforge.net
-
--Andreas Eric Dilger (former maintainer, 1996-1997)
- Internet: adilger at enel.ucalgary.ca
- Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
-
--Guy Eric Schalnat (original author and former maintainer, 1995-1996)
- (formerly of Group 42, Inc)
- Internet: gschal at infinet.com

TODO

@@ -1,30 +1,22 @@
-/*
+TODO list for libpng
-TODO - list of things to do for libpng:
+--------------------
 
-Final bug fixes.
+ * Fix all defects (duh!)
-Better C++ wrapper/full C++ implementation?
+ * cHRM transformation.
-Fix problem with C++ and EXTERN "C".
+ * Palette creation.
-cHRM transformation.
+ * "grayscale->palette" transformation and "palette->grayscale" detection.
-Remove setjmp/longjmp usage in favor of returning error codes. As a start on
+ * Improved dithering.
-  this, minimize the use of png_error(), replacing them with
+ * Multi-lingual error and warning message support.
-  png_warning(); return(0); or similar.
+ * Complete sRGB transformation.  (Currently it simply uses gamma=0.45455.)
-Palette creation.
+ * Man pages for function calls.
-Add "grayscale->palette" transformation and "palette->grayscale" detection.
+ * Better documentation.
-Improved dithering.
+ * Better filter selection
-Multi-lingual error and warning message support.
+   (e.g., counting huffman bits/precompression; filter inertia; filter costs).
-Complete sRGB transformation (presently it simply uses gamma=0.45455).
+ * Histogram creation.
-Man pages for function calls.
+ * Text conversion between different code pages (e.g., Latin-1 to Mac).
-Better documentation.
+ * Avoid building gamma tables whenever possible.
-Better filter selection
+ * Greater precision in changing to linear gamma for compositing against
-   (counting huffman bits/precompression?  filter inertia?  filter costs?).
+   background, and in doing rgb-to-gray transformations.
-Histogram creation.
+ * Investigate pre-incremented loop counters and other loop constructions.
-Text conversion between different code pages (Latin-1 -> Mac and DOS).
+ * Interpolated method of handling interlacing.
-Avoid building gamma tables whenever possible.
+ * More validations for libpng transformations.
-Use greater precision when changing to linear gamma for compositing against
-  background and doing rgb-to-gray transformation.
-Investigate pre-incremented loop counters and other loop constructions.
-Add interpolated method of handling interlacing.
-Extend pngvalid.c to validate more of the libpng transformations.
-Refactor preprocessor conditionals to compile entire statements
-
-*/

TRADEMARK

@@ -0,0 +1,8 @@
+TRADEMARK
+=========
+
+The name "libpng" has not been registered by the Copyright owners
+as a trademark in any jurisdiction.  However, because libpng has
+been distributed and maintained world-wide, continually since 1995,
+the Copyright owners claim "common-law trademark protection" in any
+jurisdiction where common-law trademark is recognized.

aclocal.m4

@@ -1,6 +1,6 @@
-# generated automatically by aclocal 1.16.1 -*- Autoconf -*-
+# generated automatically by aclocal 1.18.1 -*- Autoconf -*-
 
-# Copyright (C) 1996-2018 Free Software Foundation, Inc.
+# Copyright (C) 1996-2025 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -14,13 +14,13 @@
 m4_ifndef([AC_CONFIG_MACRO_DIRS], [m4_defun([_AM_CONFIG_MACRO_DIRS], [])m4_defun([AC_CONFIG_MACRO_DIRS], [_AM_CONFIG_MACRO_DIRS($@)])])
 m4_ifndef([AC_AUTOCONF_VERSION],
   [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
-m4_if(m4_defn([AC_AUTOCONF_VERSION]), [2.69],,
+m4_if(m4_defn([AC_AUTOCONF_VERSION]), [2.72],,
-[m4_warning([this file was generated for autoconf 2.69.
+[m4_warning([this file was generated for autoconf 2.72.
 You have another version of autoconf.  It may work, but is not guaranteed to.
 If you have problems, you may need to regenerate the build system entirely.
 To do so, use the procedure documented by the package, typically 'autoreconf'.])])
 
-# Copyright (C) 2002-2018 Free Software Foundation, Inc.
+# Copyright (C) 2002-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -32,10 +32,10 @@ To do so, use the procedure documented by the package, typically 'autoreconf'.])
 # generated from the m4 files accompanying Automake X.Y.
 # (This private macro should not be called outside this file.)
 AC_DEFUN([AM_AUTOMAKE_VERSION],
-[am__api_version='1.16'
+[am__api_version='1.18'
 dnl Some users find AM_AUTOMAKE_VERSION and mistake it for a way to
 dnl require some minimum version.  Point them to the right macro.
-m4_if([$1], [1.16.1], [],
+m4_if([$1], [1.18.1], [],
       [AC_FATAL([Do not call $0, use AM_INIT_AUTOMAKE([$1]).])])dnl
 ])
 
@@ -51,14 +51,14 @@ m4_define([_AM_AUTOCONF_VERSION], [])
 # Call AM_AUTOMAKE_VERSION and AM_AUTOMAKE_VERSION so they can be traced.
 # This function is AC_REQUIREd by AM_INIT_AUTOMAKE.
 AC_DEFUN([AM_SET_CURRENT_AUTOMAKE_VERSION],
-[AM_AUTOMAKE_VERSION([1.16.1])dnl
+[AM_AUTOMAKE_VERSION([1.18.1])dnl
 m4_ifndef([AC_AUTOCONF_VERSION],
   [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
 _AM_AUTOCONF_VERSION(m4_defn([AC_AUTOCONF_VERSION]))])
 
 # Figure out how to run the assembler.                      -*- Autoconf -*-
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -78,7 +78,7 @@ _AM_IF_OPTION([no-dependencies],, [_AM_DEPENDENCIES([CCAS])])dnl
 
 # AM_AUX_DIR_EXPAND                                         -*- Autoconf -*-
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -130,7 +130,7 @@ am_aux_dir=`cd "$ac_aux_dir" && pwd`
 
 # AM_CONDITIONAL                                            -*- Autoconf -*-
 
-# Copyright (C) 1997-2018 Free Software Foundation, Inc.
+# Copyright (C) 1997-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -161,7 +161,7 @@ AC_CONFIG_COMMANDS_PRE(
 Usually this means the macro was only invoked conditionally.]])
 fi])])
 
-# Copyright (C) 1999-2018 Free Software Foundation, Inc.
+# Copyright (C) 1999-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -293,7 +293,7 @@ AC_CACHE_CHECK([dependency style of $depcc],
       # icc doesn't choke on unknown options, it will just issue warnings
       # or remarks (even with -Werror).  So we grep stderr for any message
       # that says an option was ignored or not supported.
-      # When given -MP, icc 7.0 and 7.1 complain thusly:
+      # When given -MP, icc 7.0 and 7.1 complain thus:
       #   icc: Command line warning: ignoring option '-M'; no argument required
       # The diagnosis changed in icc 8.0:
       #   icc: Command line remark: option '-MP' not supported
@@ -352,7 +352,7 @@ _AM_SUBST_NOTMAKE([am__nodep])dnl
 
 # Generate code to set up dependency tracking.              -*- Autoconf -*-
 
-# Copyright (C) 1999-2018 Free Software Foundation, Inc.
+# Copyright (C) 1999-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -391,7 +391,9 @@ AC_DEFUN([_AM_OUTPUT_DEPENDENCY_COMMANDS],
   done
   if test $am_rc -ne 0; then
     AC_MSG_FAILURE([Something went wrong bootstrapping makefile fragments
-    for automatic dependency tracking.  Try re-running configure with the
+    for automatic dependency tracking.  If GNU make was not used, consider
+    re-running the configure script with MAKE="gmake" (or whatever is
+    necessary).  You can also try re-running configure with the
     '--disable-dependency-tracking' option to at least be able to build
     the package (albeit without support for automatic dependency tracking).])
   fi
@@ -418,7 +420,7 @@ AC_DEFUN([AM_OUTPUT_DEPENDENCY_COMMANDS],
 
 # Do all the work for Automake.                             -*- Autoconf -*-
 
-# Copyright (C) 1996-2018 Free Software Foundation, Inc.
+# Copyright (C) 1996-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -446,6 +448,10 @@ m4_defn([AC_PROG_CC])
 # release and drop the old call support.
 AC_DEFUN([AM_INIT_AUTOMAKE],
 [AC_PREREQ([2.65])dnl
+m4_ifdef([_$0_ALREADY_INIT],
+  [m4_fatal([$0 expanded multiple times
+]m4_defn([_$0_ALREADY_INIT]))],
+  [m4_define([_$0_ALREADY_INIT], m4_expansion_stack)])dnl
 dnl Autoconf wants to disallow AM_ names.  We explicitly allow
 dnl the ones we care about.
 m4_pattern_allow([^AM_[A-Z]+FLAGS$])dnl
@@ -482,7 +488,7 @@ m4_ifval([$3], [_AM_SET_OPTION([no-define])])dnl
 [_AM_SET_OPTIONS([$1])dnl
 dnl Diagnose old-style AC_INIT with new-style AM_AUTOMAKE_INIT.
 m4_if(
-  m4_ifdef([AC_PACKAGE_NAME], [ok]):m4_ifdef([AC_PACKAGE_VERSION], [ok]),
+  m4_ifset([AC_PACKAGE_NAME], [ok]):m4_ifset([AC_PACKAGE_VERSION], [ok]),
   [ok:ok],,
   [m4_fatal([AC_INIT should be called with package and version arguments])])dnl
  AC_SUBST([PACKAGE], ['AC_PACKAGE_TARNAME'])dnl
@@ -514,8 +520,9 @@ AC_REQUIRE([AC_PROG_AWK])dnl
 AC_REQUIRE([AC_PROG_MAKE_SET])dnl
 AC_REQUIRE([AM_SET_LEADING_DOT])dnl
 _AM_IF_OPTION([tar-ustar], [_AM_PROG_TAR([ustar])],
-	      [_AM_IF_OPTION([tar-pax], [_AM_PROG_TAR([pax])],
+  [_AM_IF_OPTION([tar-pax], [_AM_PROG_TAR([pax])],
-			     [_AM_PROG_TAR([v7])])])
+    [_AM_IF_OPTION([tar-v7], [_AM_PROG_TAR([v7])],
+      [_AM_PROG_TAR([ustar])])])])
 _AM_IF_OPTION([no-dependencies],,
 [AC_PROVIDE_IFELSE([AC_PROG_CC],
 		  [_AM_DEPENDENCIES([CC])],
@@ -534,7 +541,21 @@ AC_PROVIDE_IFELSE([AC_PROG_OBJCXX],
 		  [m4_define([AC_PROG_OBJCXX],
 			     m4_defn([AC_PROG_OBJCXX])[_AM_DEPENDENCIES([OBJCXX])])])dnl
 ])
-AC_REQUIRE([AM_SILENT_RULES])dnl
+# Variables for tags utilities; see am/tags.am
+if test -z "$CTAGS"; then
+  CTAGS=ctags
+fi
+AC_SUBST([CTAGS])
+if test -z "$ETAGS"; then
+  ETAGS=etags
+fi
+AC_SUBST([ETAGS])
+if test -z "$CSCOPE"; then
+  CSCOPE=cscope
+fi
+AC_SUBST([CSCOPE])
+
+AC_REQUIRE([_AM_SILENT_RULES])dnl
 dnl The testsuite driver may need to know about EXEEXT, so add the
 dnl 'am__EXEEXT' conditional if _AM_COMPILER_EXEEXT was seen.  This
 dnl macro is hooked onto _AC_COMPILER_EXEEXT early, see below.
@@ -542,47 +563,9 @@ AC_CONFIG_COMMANDS_PRE(dnl
 [m4_provide_if([_AM_COMPILER_EXEEXT],
   [AM_CONDITIONAL([am__EXEEXT], [test -n "$EXEEXT"])])])dnl
 
-# POSIX will say in a future version that running "rm -f" with no argument
+AC_REQUIRE([_AM_PROG_RM_F])
-# is OK; and we want to be able to make that assumption in our Makefile
+AC_REQUIRE([_AM_PROG_XARGS_N])
-# recipes.  So use an aggressive probe to check that the usage we want is
-# actually supported "in the wild" to an acceptable degree.
-# See automake bug#10828.
-# To make any issue more visible, cause the running configure to be aborted
-# by default if the 'rm' program in use doesn't match our expectations; the
-# user can still override this though.
-if rm -f && rm -fr && rm -rf; then : OK; else
-  cat >&2 <<'END'
-Oops!
 
-Your 'rm' program seems unable to run without file operands specified
-on the command line, even when the '-f' option is present.  This is contrary
-to the behaviour of most rm programs out there, and not conforming with
-the upcoming POSIX standard: <http://austingroupbugs.net/view.php?id=542>
-
-Please tell bug-automake@gnu.org about your system, including the value
-of your $PATH and any error possibly output before this message.  This
-can help us improve future automake versions.
-
-END
-  if test x"$ACCEPT_INFERIOR_RM_PROGRAM" = x"yes"; then
-    echo 'Configuration will proceed anyway, since you have set the' >&2
-    echo 'ACCEPT_INFERIOR_RM_PROGRAM variable to "yes"' >&2
-    echo >&2
-  else
-    cat >&2 <<'END'
-Aborting the configuration process, to ensure you take notice of the issue.
-
-You can download and install GNU coreutils to get an 'rm' implementation
-that behaves properly: <https://www.gnu.org/software/coreutils/>.
-
-If you want to complete the configuration process using your problematic
-'rm' anyway, export the environment variable ACCEPT_INFERIOR_RM_PROGRAM
-to "yes", and re-run configure.
-
-END
-    AC_MSG_ERROR([Your 'rm' program is bad, sorry.])
-  fi
-fi
 dnl The trailing newline in this macro's definition is deliberate, for
 dnl backward compatibility and to allow trailing 'dnl'-style comments
 dnl after the AM_INIT_AUTOMAKE invocation. See automake bug#16841.
@@ -615,7 +598,7 @@ for _am_header in $config_headers :; do
 done
 echo "timestamp for $_am_arg" >`AS_DIRNAME(["$_am_arg"])`/stamp-h[]$_am_stamp_count])
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -636,7 +619,7 @@ if test x"${install_sh+set}" != xset; then
 fi
 AC_SUBST([install_sh])])
 
-# Copyright (C) 2003-2018 Free Software Foundation, Inc.
+# Copyright (C) 2003-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -658,7 +641,7 @@ AC_SUBST([am__leading_dot])])
 # Add --enable-maintainer-mode option to configure.         -*- Autoconf -*-
 # From Jim Meyering
 
-# Copyright (C) 1996-2018 Free Software Foundation, Inc.
+# Copyright (C) 1996-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -693,7 +676,7 @@ AC_MSG_CHECKING([whether to enable maintainer-specific portions of Makefiles])
 
 # Check to see how 'make' treats includes.	            -*- Autoconf -*-
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -736,7 +719,7 @@ AC_SUBST([am__quote])])
 
 # Fake the existence of programs that GNU maintainers use.  -*- Autoconf -*-
 
-# Copyright (C) 1997-2018 Free Software Foundation, Inc.
+# Copyright (C) 1997-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -757,12 +740,7 @@ AC_DEFUN([AM_MISSING_HAS_RUN],
 [AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
 AC_REQUIRE_AUX_FILE([missing])dnl
 if test x"${MISSING+set}" != xset; then
-  case $am_aux_dir in
+  MISSING="\${SHELL} '$am_aux_dir/missing'"
-  *\ * | *\	*)
-    MISSING="\${SHELL} \"$am_aux_dir/missing\"" ;;
-  *)
-    MISSING="\${SHELL} $am_aux_dir/missing" ;;
-  esac
 fi
 # Use eval to expand $SHELL
 if eval "$MISSING --is-lightweight"; then
@@ -775,7 +753,7 @@ fi
 
 # Helper functions for option handling.                     -*- Autoconf -*-
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -804,7 +782,7 @@ AC_DEFUN([_AM_SET_OPTIONS],
 AC_DEFUN([_AM_IF_OPTION],
 [m4_ifset(_AM_MANGLE_OPTION([$1]), [$2], [$3])])
 
-# Copyright (C) 1999-2018 Free Software Foundation, Inc.
+# Copyright (C) 1999-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -836,7 +814,10 @@ AC_CACHE_CHECK(
       break
     fi
   done
-  rm -f core conftest*
+  # aligned with autoconf, so not including core; see bug#72225.
+  rm -f -r a.out a.exe b.out conftest.$ac_ext conftest.$ac_objext \
+    conftest.dSYM conftest1.$ac_ext conftest1.$ac_objext conftest1.dSYM \
+    conftest2.$ac_ext conftest2.$ac_objext conftest2.dSYM
   unset am_i])
 if test "$am_cv_prog_cc_c_o" != yes; then
    # Losing compiler, so override with the script.
@@ -851,7 +832,23 @@ AC_LANG_POP([C])])
 # For backward compatibility.
 AC_DEFUN_ONCE([AM_PROG_CC_C_O], [AC_REQUIRE([AC_PROG_CC])])
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# Copyright (C) 2022-2025 Free Software Foundation, Inc.
+#
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# _AM_PROG_RM_F
+# ---------------
+# Check whether 'rm -f' without any arguments works.
+# https://bugs.gnu.org/10828
+AC_DEFUN([_AM_PROG_RM_F],
+[am__rm_f_notfound=
+AS_IF([(rm -f && rm -fr && rm -rf) 2>/dev/null], [], [am__rm_f_notfound='""'])
+AC_SUBST(am__rm_f_notfound)
+])
+
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -870,26 +867,181 @@ AC_DEFUN([AM_RUN_LOG],
 
 # Check to make sure that the build environment is sane.    -*- Autoconf -*-
 
-# Copyright (C) 1996-2018 Free Software Foundation, Inc.
+# Copyright (C) 1996-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
+# _AM_SLEEP_FRACTIONAL_SECONDS
+# ----------------------------
+AC_DEFUN([_AM_SLEEP_FRACTIONAL_SECONDS], [dnl
+AC_CACHE_CHECK([whether sleep supports fractional seconds],
+               am_cv_sleep_fractional_seconds, [dnl
+AS_IF([sleep 0.001 2>/dev/null], [am_cv_sleep_fractional_seconds=yes],
+                                 [am_cv_sleep_fractional_seconds=no])
+])])
+
+# _AM_FILESYSTEM_TIMESTAMP_RESOLUTION
+# -----------------------------------
+# Determine the filesystem's resolution for file modification
+# timestamps.  The coarsest we know of is FAT, with a resolution
+# of only two seconds, even with the most recent "exFAT" extensions.
+# The finest (e.g. ext4 with large inodes, XFS, ZFS) is one
+# nanosecond, matching clock_gettime.  However, it is probably not
+# possible to delay execution of a shell script for less than one
+# millisecond, due to process creation overhead and scheduling
+# granularity, so we don't check for anything finer than that. (See below.)
+AC_DEFUN([_AM_FILESYSTEM_TIMESTAMP_RESOLUTION], [dnl
+AC_REQUIRE([_AM_SLEEP_FRACTIONAL_SECONDS])
+AC_CACHE_CHECK([filesystem timestamp resolution],
+               am_cv_filesystem_timestamp_resolution, [dnl
+# Default to the worst case.
+am_cv_filesystem_timestamp_resolution=2
+
+# Only try to go finer than 1 sec if sleep can do it.
+# Don't try 1 sec, because if 0.01 sec and 0.1 sec don't work,
+# - 1 sec is not much of a win compared to 2 sec, and
+# - it takes 2 seconds to perform the test whether 1 sec works.
+# 
+# Instead, just use the default 2s on platforms that have 1s resolution,
+# accept the extra 1s delay when using $sleep in the Automake tests, in
+# exchange for not incurring the 2s delay for running the test for all
+# packages.
+#
+am_try_resolutions=
+if test "$am_cv_sleep_fractional_seconds" = yes; then
+  # Even a millisecond often causes a bunch of false positives,
+  # so just try a hundredth of a second. The time saved between .001 and
+  # .01 is not terribly consequential.
+  am_try_resolutions="0.01 0.1 $am_try_resolutions"
+fi
+
+# In order to catch current-generation FAT out, we must *modify* files
+# that already exist; the *creation* timestamp is finer.  Use names
+# that make ls -t sort them differently when they have equal
+# timestamps than when they have distinct timestamps, keeping
+# in mind that ls -t prints the *newest* file first.
+rm -f conftest.ts?
+: > conftest.ts1
+: > conftest.ts2
+: > conftest.ts3
+
+# Make sure ls -t actually works.  Do 'set' in a subshell so we don't
+# clobber the current shell's arguments. (Outer-level square brackets
+# are removed by m4; they're present so that m4 does not expand
+# <dollar><star>; be careful, easy to get confused.)
+if (
+     set X `[ls -t conftest.ts[12]]` &&
+     {
+       test "$[]*" != "X conftest.ts1 conftest.ts2" ||
+       test "$[]*" != "X conftest.ts2 conftest.ts1";
+     }
+); then :; else
+  # If neither matched, then we have a broken ls.  This can happen
+  # if, for instance, CONFIG_SHELL is bash and it inherits a
+  # broken ls alias from the environment.  This has actually
+  # happened.  Such a system could not be considered "sane".
+  _AS_ECHO_UNQUOTED(
+    ["Bad output from ls -t: \"`[ls -t conftest.ts[12]]`\""],
+    [AS_MESSAGE_LOG_FD])
+  AC_MSG_FAILURE([ls -t produces unexpected output.
+Make sure there is not a broken ls alias in your environment.])
+fi
+
+for am_try_res in $am_try_resolutions; do
+  # Any one fine-grained sleep might happen to cross the boundary
+  # between two values of a coarser actual resolution, but if we do
+  # two fine-grained sleeps in a row, at least one of them will fall
+  # entirely within a coarse interval.
+  echo alpha > conftest.ts1
+  sleep $am_try_res
+  echo beta > conftest.ts2
+  sleep $am_try_res
+  echo gamma > conftest.ts3
+
+  # We assume that 'ls -t' will make use of high-resolution
+  # timestamps if the operating system supports them at all.
+  if (set X `ls -t conftest.ts?` &&
+      test "$[]2" = conftest.ts3 &&
+      test "$[]3" = conftest.ts2 &&
+      test "$[]4" = conftest.ts1); then
+    #
+    # Ok, ls -t worked. If we're at a resolution of 1 second, we're done,
+    # because we don't need to test make.
+    make_ok=true
+    if test $am_try_res != 1; then
+      # But if we've succeeded so far with a subsecond resolution, we
+      # have one more thing to check: make. It can happen that
+      # everything else supports the subsecond mtimes, but make doesn't;
+      # notably on macOS, which ships make 3.81 from 2006 (the last one
+      # released under GPLv2). https://bugs.gnu.org/68808
+      # 
+      # We test $MAKE if it is defined in the environment, else "make".
+      # It might get overridden later, but our hope is that in practice
+      # it does not matter: it is the system "make" which is (by far)
+      # the most likely to be broken, whereas if the user overrides it,
+      # probably they did so with a better, or at least not worse, make.
+      # https://lists.gnu.org/archive/html/automake/2024-06/msg00051.html
+      #
+      # Create a Makefile (real tab character here):
+      rm -f conftest.mk
+      echo 'conftest.ts1: conftest.ts2' >conftest.mk
+      echo '	touch conftest.ts2' >>conftest.mk
+      #
+      # Now, running
+      #   touch conftest.ts1; touch conftest.ts2; make
+      # should touch ts1 because ts2 is newer. This could happen by luck,
+      # but most often, it will fail if make's support is insufficient. So
+      # test for several consecutive successes.
+      #
+      # (We reuse conftest.ts[12] because we still want to modify existing
+      # files, not create new ones, per above.)
+      n=0
+      make=${MAKE-make}
+      until test $n -eq 3; do
+        echo one > conftest.ts1
+        sleep $am_try_res
+        echo two > conftest.ts2 # ts2 should now be newer than ts1
+        if $make -f conftest.mk | grep 'up to date' >/dev/null; then
+          make_ok=false
+          break # out of $n loop
+        fi
+        n=`expr $n + 1`
+      done
+    fi
+    #
+    if $make_ok; then
+      # Everything we know to check worked out, so call this resolution good.
+      am_cv_filesystem_timestamp_resolution=$am_try_res
+      break # out of $am_try_res loop
+    fi
+    # Otherwise, we'll go on to check the next resolution.
+  fi
+done
+rm -f conftest.ts?
+# (end _am_filesystem_timestamp_resolution)
+])])
+
 # AM_SANITY_CHECK
 # ---------------
 AC_DEFUN([AM_SANITY_CHECK],
-[AC_MSG_CHECKING([whether build environment is sane])
+[AC_REQUIRE([_AM_FILESYSTEM_TIMESTAMP_RESOLUTION])
+# This check should not be cached, as it may vary across builds of
+# different projects.
+AC_MSG_CHECKING([whether build environment is sane])
 # Reject unsafe characters in $srcdir or the absolute working directory
 # name.  Accept space and tab only in the latter.
 am_lf='
 '
 case `pwd` in
   *[[\\\"\#\$\&\'\`$am_lf]]*)
+    AC_MSG_RESULT([no])
     AC_MSG_ERROR([unsafe absolute working directory name]);;
 esac
 case $srcdir in
   *[[\\\"\#\$\&\'\`$am_lf\ \	]]*)
+    AC_MSG_RESULT([no])
     AC_MSG_ERROR([unsafe srcdir value: '$srcdir']);;
 esac
 
@@ -898,49 +1050,40 @@ esac
 # symlink; some systems play weird games with the mod time of symlinks
 # (eg FreeBSD returns the mod time of the symlink's containing
 # directory).
-if (
+am_build_env_is_sane=no
-   am_has_slept=no
+am_has_slept=no
-   for am_try in 1 2; do
+rm -f conftest.file
-     echo "timestamp, slept: $am_has_slept" > conftest.file
+for am_try in 1 2; do
-     set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
+  echo "timestamp, slept: $am_has_slept" > conftest.file
-     if test "$[*]" = "X"; then
+  if (
-	# -L didn't work.
+    set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
-	set X `ls -t "$srcdir/configure" conftest.file`
+    if test "$[]*" = "X"; then
-     fi
+      # -L didn't work.
-     if test "$[*]" != "X $srcdir/configure conftest.file" \
+      set X `ls -t "$srcdir/configure" conftest.file`
-	&& test "$[*]" != "X conftest.file $srcdir/configure"; then
+    fi
+    test "$[]2" = conftest.file
+  ); then
+    am_build_env_is_sane=yes
+    break
+  fi
+  # Just in case.
+  sleep "$am_cv_filesystem_timestamp_resolution"
+  am_has_slept=yes
+done
 
-	# If neither matched, then we have a broken ls.  This can happen
+AC_MSG_RESULT([$am_build_env_is_sane])
-	# if, for instance, CONFIG_SHELL is bash and it inherits a
+if test "$am_build_env_is_sane" = no; then
-	# broken ls alias from the environment.  This has actually
+  AC_MSG_ERROR([newly created file is older than distributed files!
-	# happened.  Such a system could not be considered "sane".
-	AC_MSG_ERROR([ls -t appears to fail.  Make sure there is not a broken
-  alias in your environment])
-     fi
-     if test "$[2]" = conftest.file || test $am_try -eq 2; then
-       break
-     fi
-     # Just in case.
-     sleep 1
-     am_has_slept=yes
-   done
-   test "$[2]" = conftest.file
-   )
-then
-   # Ok.
-   :
-else
-   AC_MSG_ERROR([newly created file is older than distributed files!
 Check your system clock])
 fi
-AC_MSG_RESULT([yes])
+
 # If we didn't sleep, we still need to ensure time stamps of config.status and
 # generated files are strictly newer.
 am_sleep_pid=
-if grep 'slept: no' conftest.file >/dev/null 2>&1; then
+AS_IF([test -e conftest.file || grep 'slept: no' conftest.file >/dev/null 2>&1],, [dnl
-  ( sleep 1 ) &
+  ( sleep "$am_cv_filesystem_timestamp_resolution" ) &
   am_sleep_pid=$!
-fi
+])
 AC_CONFIG_COMMANDS_PRE(
   [AC_MSG_CHECKING([that generated files are newer than configure])
    if test -n "$am_sleep_pid"; then
@@ -951,18 +1094,18 @@ AC_CONFIG_COMMANDS_PRE(
 rm -f conftest.file
 ])
 
-# Copyright (C) 2009-2018 Free Software Foundation, Inc.
+# Copyright (C) 2009-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# AM_SILENT_RULES([DEFAULT])
+# _AM_SILENT_RULES
-# --------------------------
+# ----------------
-# Enable less verbose build rules; with the default set to DEFAULT
+# Enable less verbose build rules support.
-# ("yes" being less verbose, "no" or empty being verbose).
+AC_DEFUN([_AM_SILENT_RULES],
-AC_DEFUN([AM_SILENT_RULES],
+[AM_DEFAULT_VERBOSITY=1
-[AC_ARG_ENABLE([silent-rules], [dnl
+AC_ARG_ENABLE([silent-rules], [dnl
 AS_HELP_STRING(
   [--enable-silent-rules],
   [less verbose build output (undo: "make V=1")])
@@ -970,11 +1113,6 @@ AS_HELP_STRING(
   [--disable-silent-rules],
   [verbose build output (undo: "make V=0")])dnl
 ])
-case $enable_silent_rules in @%:@ (((
-  yes) AM_DEFAULT_VERBOSITY=0;;
-   no) AM_DEFAULT_VERBOSITY=1;;
-    *) AM_DEFAULT_VERBOSITY=m4_if([$1], [yes], [0], [1]);;
-esac
 dnl
 dnl A few 'make' implementations (e.g., NonStop OS and NextStep)
 dnl do not support nested variable expansions.
@@ -993,14 +1131,6 @@ am__doit:
 else
   am_cv_make_support_nested_variables=no
 fi])
-if test $am_cv_make_support_nested_variables = yes; then
-  dnl Using '$V' instead of '$(V)' breaks IRIX make.
-  AM_V='$(V)'
-  AM_DEFAULT_V='$(AM_DEFAULT_VERBOSITY)'
-else
-  AM_V=$AM_DEFAULT_VERBOSITY
-  AM_DEFAULT_V=$AM_DEFAULT_VERBOSITY
-fi
 AC_SUBST([AM_V])dnl
 AM_SUBST_NOTMAKE([AM_V])dnl
 AC_SUBST([AM_DEFAULT_V])dnl
@@ -1009,9 +1139,37 @@ AC_SUBST([AM_DEFAULT_VERBOSITY])dnl
 AM_BACKSLASH='\'
 AC_SUBST([AM_BACKSLASH])dnl
 _AM_SUBST_NOTMAKE([AM_BACKSLASH])dnl
+dnl Delay evaluation of AM_DEFAULT_VERBOSITY to the end to allow multiple calls
+dnl to AM_SILENT_RULES to change the default value.
+AC_CONFIG_COMMANDS_PRE([dnl
+case $enable_silent_rules in @%:@ (((
+  yes) AM_DEFAULT_VERBOSITY=0;;
+   no) AM_DEFAULT_VERBOSITY=1;;
+esac
+if test $am_cv_make_support_nested_variables = yes; then
+  dnl Using '$V' instead of '$(V)' breaks IRIX make.
+  AM_V='$(V)'
+  AM_DEFAULT_V='$(AM_DEFAULT_VERBOSITY)'
+else
+  AM_V=$AM_DEFAULT_VERBOSITY
+  AM_DEFAULT_V=$AM_DEFAULT_VERBOSITY
+fi
+])dnl
 ])
 
-# Copyright (C) 2001-2018 Free Software Foundation, Inc.
+# AM_SILENT_RULES([DEFAULT])
+# --------------------------
+# Set the default verbosity level to DEFAULT ("yes" being less verbose, "no" or
+# empty being verbose).
+AC_DEFUN([AM_SILENT_RULES],
+[AC_REQUIRE([_AM_SILENT_RULES])
+AM_DEFAULT_VERBOSITY=m4_if([$1], [yes], [0], [1])m4_newline
+dnl We intentionally force a newline after the assignment, since a) nothing
+dnl good can come of more text following, and b) that was the behavior
+dnl before 1.17. See https://bugs.gnu.org/72267.
+])
+
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -1039,7 +1197,7 @@ fi
 INSTALL_STRIP_PROGRAM="\$(install_sh) -c -s"
 AC_SUBST([INSTALL_STRIP_PROGRAM])])
 
-# Copyright (C) 2006-2018 Free Software Foundation, Inc.
+# Copyright (C) 2006-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -1058,7 +1216,7 @@ AC_DEFUN([AM_SUBST_NOTMAKE], [_AM_SUBST_NOTMAKE($@)])
 
 # Check how to create a tarball.                            -*- Autoconf -*-
 
-# Copyright (C) 2004-2018 Free Software Foundation, Inc.
+# Copyright (C) 2004-2025 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -1104,15 +1262,19 @@ m4_if([$1], [v7],
       am_uid=`id -u || echo unknown`
       am_gid=`id -g || echo unknown`
       AC_MSG_CHECKING([whether UID '$am_uid' is supported by ustar format])
-      if test $am_uid -le $am_max_uid; then
+      if test x$am_uid = xunknown; then
-         AC_MSG_RESULT([yes])
+        AC_MSG_WARN([ancient id detected; assuming current UID is ok, but dist-ustar might not work])
+      elif test $am_uid -le $am_max_uid; then
+        AC_MSG_RESULT([yes])
       else
-         AC_MSG_RESULT([no])
+        AC_MSG_RESULT([no])
-         _am_tools=none
+        _am_tools=none
       fi
       AC_MSG_CHECKING([whether GID '$am_gid' is supported by ustar format])
-      if test $am_gid -le $am_max_gid; then
+      if test x$gm_gid = xunknown; then
-         AC_MSG_RESULT([yes])
+        AC_MSG_WARN([ancient id detected; assuming current GID is ok, but dist-ustar might not work])
+      elif test $am_gid -le $am_max_gid; then
+        AC_MSG_RESULT([yes])
       else
         AC_MSG_RESULT([no])
         _am_tools=none
@@ -1189,8 +1351,28 @@ AC_SUBST([am__tar])
 AC_SUBST([am__untar])
 ]) # _AM_PROG_TAR
 
-m4_include([scripts/libtool.m4])
+# Copyright (C) 2022-2025 Free Software Foundation, Inc.
-m4_include([scripts/ltoptions.m4])
+#
-m4_include([scripts/ltsugar.m4])
+# This file is free software; the Free Software Foundation
-m4_include([scripts/ltversion.m4])
+# gives unlimited permission to copy and/or distribute it,
-m4_include([scripts/lt~obsolete.m4])
+# with or without modifications, as long as this notice is preserved.
+
+# _AM_PROG_XARGS_N
+# ----------------
+# Check whether 'xargs -n' works.  It should work everywhere, so the fallback
+# is not optimized at all as we never expect to use it.
+AC_DEFUN([_AM_PROG_XARGS_N],
+[AC_CACHE_CHECK([xargs -n works], am_cv_xargs_n_works, [dnl
+AS_IF([test "`echo 1 2 3 | xargs -n2 echo`" = "1 2
+3"], [am_cv_xargs_n_works=yes], [am_cv_xargs_n_works=no])])
+AS_IF([test "$am_cv_xargs_n_works" = yes], [am__xargs_n='xargs -n'], [dnl
+  am__xargs_n='am__xargs_n () { shift; sed "s/ /\\n/g" | while read am__xargs_n_arg; do "$@" "$am__xargs_n_arg"; done; }'
+])dnl
+AC_SUBST(am__xargs_n)
+])
+
+m4_include([scripts/autoconf/libtool.m4])
+m4_include([scripts/autoconf/ltoptions.m4])
+m4_include([scripts/autoconf/ltsugar.m4])
+m4_include([scripts/autoconf/ltversion.m4])
+m4_include([scripts/autoconf/lt~obsolete.m4])

arm/arm_init.c

@@ -1,17 +1,15 @@
-
 /* arm_init.c - NEON optimised filter functions
  *
+ * Copyright (c) 2018-2022 Cosmin Truta
  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
  * Written by Mans Rullgard, 2011.
- * 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
  */
-/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
+
- * called.
+/* This module requires POSIX 1003.1 functions. */
- */
 #define _POSIX_SOURCE 1
 
 #include "../pngpriv.h"
@@ -32,25 +30,30 @@
  * has partial support is contrib/arm-neon/linux.c - a generic Linux
  * implementation which reads /proc/cpufino.
  */
+#include <signal.h> /* for sig_atomic_t */
+
 #ifndef PNG_ARM_NEON_FILE
-#  ifdef __linux__
+#  if defined(__aarch64__) || defined(_M_ARM64)
-#     define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+     /* ARM Neon is expected to be unconditionally available on ARM64. */
+#    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on ARM64
+#  elif defined(__ARM_NEON__) || defined(__ARM_NEON)
+     /* ARM Neon is expected to be available on the target CPU architecture. */
+#    error PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on this CPU arch
+#  elif defined(__linux__)
+#    define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+#  else
+#    error No support for run-time ARM Neon checking; use compile-time options
 #  endif
 #endif
 
-#ifdef PNG_ARM_NEON_FILE
-
-#include <signal.h> /* for sig_atomic_t */
 static int png_have_neon(png_structp png_ptr);
-#include PNG_ARM_NEON_FILE
+#ifdef PNG_ARM_NEON_FILE
-
+#  include PNG_ARM_NEON_FILE
-#else  /* PNG_ARM_NEON_FILE */
+#endif
-#  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
-#endif /* PNG_ARM_NEON_FILE */
 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
 
 #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
-#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
+#  error ALIGNED_MEMORY is required; please define PNG_ALIGNED_MEMORY_SUPPORTED
 #endif
 
 void

arm/filter_neon.S

@@ -1,253 +1,60 @@
-
+/* filter_neon.S - placeholder file
-/* filter_neon.S - NEON optimised filter functions
  *
- * Copyright (c) 2014,2017 Glenn Randers-Pehrson
+ * Copyright (c) 2024 Cosmin Truta
- * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.31 [July 27, 2017]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
 
+/* IMPORTANT NOTE:
+ *
+ * Historically, the hand-coded assembler implementation of Neon optimizations
+ * in this module had not been in sync with the intrinsics-based implementation
+ * in filter_neon_intrinsics.c and palette_neon_intrinsics.c, at least since
+ * the introduction of riffled palette optimizations. Moreover, the assembler
+ * code used to work on 32-bit ARM only, and it caused problems, even if empty,
+ * on 64-bit ARM.
+ *
+ * All references to this module from our internal build scripts and projects
+ * have been removed.
+ *
+ * For the external projects that might still expect this module to be present,
+ * we leave this stub in place, for the remaining lifetime of libpng-1.6.x.
+ * Everything should continue to function normally, as long as there are no
+ * deliberate attempts to use the old hand-made assembler code. A build error
+ * will be raised otherwise.
+ */
+
 /* This is required to get the symbol renames, which are #defines, and the
  * definitions (or not) of PNG_ARM_NEON_OPT and PNG_ARM_NEON_IMPLEMENTATION.
  */
 #define PNG_VERSION_INFO_ONLY
 #include "../pngpriv.h"
 
-#if (defined(__linux__) || defined(__FreeBSD__)) && defined(__ELF__)
-.section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
-#endif
-
 #ifdef PNG_READ_SUPPORTED
-
-/* Assembler NEON support - only works for 32-bit ARM (i.e. it does not work for
- * ARM64).  The code in arm/filter_neon_intrinsics.c supports ARM64, however it
- * only works if -mfpu=neon is specified on the GCC command line.  See pngpriv.h
- * for the logic which sets PNG_USE_ARM_NEON_ASM:
- */
 #if PNG_ARM_NEON_IMPLEMENTATION == 2 /* hand-coded assembler */
-
 #if PNG_ARM_NEON_OPT > 0
 
-#ifdef __ELF__
+#if defined(__clang__)
-#   define ELF
+#define GNUC_VERSION 0 /* not gcc, although it might pretend to be */
+#elif defined(__GNUC__)
+#define GNUC_MAJOR (__GNUC__ + 0)
+#define GNUC_MINOR (__GNUC_MINOR__ + 0)
+#define GNUC_PATCHLEVEL (__GNUC_PATCHLEVEL__ + 0)
+#define GNUC_VERSION (GNUC_MAJOR * 10000 + GNUC_MINOR * 100 + GNUC_PATCHLEVEL)
 #else
-#   define ELF @
+#define GNUC_VERSION 0 /* not gcc */
 #endif
 
-        .arch armv7-a
+#if (GNUC_VERSION > 0) && (GNUC_VERSION < 40300)
-        .fpu  neon
+#error "PNG_ARM_NEON is not supported with gcc versions earlier than 4.3.0"
+#elif GNUC_VERSION == 40504
+#error "PNG_ARM_NEON is not supported with gcc version 4.5.4"
+#else
+#error "Please use 'arm/*_neon_intrinsics.c' for PNG_ARM_NEON support"
+#endif
 
-.macro  func    name, export=0
-    .macro endfunc
-ELF     .size   \name, . - \name
-        .endfunc
-        .purgem endfunc
-    .endm
-        .text
-
-        /* Explicitly specifying alignment here because some versions of
-         * GAS don't align code correctly.  This is harmless in correctly
-         * written versions of GAS.
-         */
-        .align 2
-
-    .if \export
-        .global \name
-    .endif
-ELF     .type   \name, STT_FUNC
-        .func   \name
-\name:
-.endm
-
-func    png_read_filter_row_sub4_neon, export=1
-        ldr             r3,  [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-1:
-        vld4.32         {d4[],d5[],d6[],d7[]},    [r1,:128]
-        vadd.u8         d0,  d3,  d4
-        vadd.u8         d1,  d0,  d5
-        vadd.u8         d2,  d1,  d6
-        vadd.u8         d3,  d2,  d7
-        vst4.32         {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
-        subs            r3,  r3,  #16
-        bgt             1b
-
-        bx              lr
-endfunc
-
-func    png_read_filter_row_sub3_neon, export=1
-        ldr             r3,  [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-        mov             r0,  r1
-        mov             r2,  #3
-        mov             r12, #12
-        vld1.8          {q11},    [r0], r12
-1:
-        vext.8          d5,  d22, d23, #3
-        vadd.u8         d0,  d3,  d22
-        vext.8          d6,  d22, d23, #6
-        vadd.u8         d1,  d0,  d5
-        vext.8          d7,  d23, d23, #1
-        vld1.8          {q11},    [r0], r12
-        vst1.32         {d0[0]},  [r1,:32], r2
-        vadd.u8         d2,  d1,  d6
-        vst1.32         {d1[0]},  [r1], r2
-        vadd.u8         d3,  d2,  d7
-        vst1.32         {d2[0]},  [r1], r2
-        vst1.32         {d3[0]},  [r1], r2
-        subs            r3,  r3,  #12
-        bgt             1b
-
-        bx              lr
-endfunc
-
-func    png_read_filter_row_up_neon, export=1
-        ldr             r3,  [r0, #4]           @ rowbytes
-1:
-        vld1.8          {q0}, [r1,:128]
-        vld1.8          {q1}, [r2,:128]!
-        vadd.u8         q0,  q0,  q1
-        vst1.8          {q0}, [r1,:128]!
-        subs            r3,  r3,  #16
-        bgt             1b
-
-        bx              lr
-endfunc
-
-func    png_read_filter_row_avg4_neon, export=1
-        ldr             r12, [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-1:
-        vld4.32         {d4[],d5[],d6[],d7[]},    [r1,:128]
-        vld4.32         {d16[],d17[],d18[],d19[]},[r2,:128]!
-        vhadd.u8        d0,  d3,  d16
-        vadd.u8         d0,  d0,  d4
-        vhadd.u8        d1,  d0,  d17
-        vadd.u8         d1,  d1,  d5
-        vhadd.u8        d2,  d1,  d18
-        vadd.u8         d2,  d2,  d6
-        vhadd.u8        d3,  d2,  d19
-        vadd.u8         d3,  d3,  d7
-        vst4.32         {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
-        subs            r12, r12, #16
-        bgt             1b
-
-        bx              lr
-endfunc
-
-func    png_read_filter_row_avg3_neon, export=1
-        push            {r4,lr}
-        ldr             r12, [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-        mov             r0,  r1
-        mov             r4,  #3
-        mov             lr,  #12
-        vld1.8          {q11},    [r0], lr
-1:
-        vld1.8          {q10},    [r2], lr
-        vext.8          d5,  d22, d23, #3
-        vhadd.u8        d0,  d3,  d20
-        vext.8          d17, d20, d21, #3
-        vadd.u8         d0,  d0,  d22
-        vext.8          d6,  d22, d23, #6
-        vhadd.u8        d1,  d0,  d17
-        vext.8          d18, d20, d21, #6
-        vadd.u8         d1,  d1,  d5
-        vext.8          d7,  d23, d23, #1
-        vld1.8          {q11},    [r0], lr
-        vst1.32         {d0[0]},  [r1,:32], r4
-        vhadd.u8        d2,  d1,  d18
-        vst1.32         {d1[0]},  [r1], r4
-        vext.8          d19, d21, d21, #1
-        vadd.u8         d2,  d2,  d6
-        vhadd.u8        d3,  d2,  d19
-        vst1.32         {d2[0]},  [r1], r4
-        vadd.u8         d3,  d3,  d7
-        vst1.32         {d3[0]},  [r1], r4
-        subs            r12, r12, #12
-        bgt             1b
-
-        pop             {r4,pc}
-endfunc
-
-.macro  paeth           rx,  ra,  rb,  rc
-        vaddl.u8        q12, \ra, \rb           @ a + b
-        vaddl.u8        q15, \rc, \rc           @ 2*c
-        vabdl.u8        q13, \rb, \rc           @ pa
-        vabdl.u8        q14, \ra, \rc           @ pb
-        vabd.u16        q15, q12, q15           @ pc
-        vcle.u16        q12, q13, q14           @ pa <= pb
-        vcle.u16        q13, q13, q15           @ pa <= pc
-        vcle.u16        q14, q14, q15           @ pb <= pc
-        vand            q12, q12, q13           @ pa <= pb && pa <= pc
-        vmovn.u16       d28, q14
-        vmovn.u16       \rx, q12
-        vbsl            d28, \rb, \rc
-        vbsl            \rx, \ra, d28
-.endm
-
-func    png_read_filter_row_paeth4_neon, export=1
-        ldr             r12, [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-        vmov.i8         d20, #0
-1:
-        vld4.32         {d4[],d5[],d6[],d7[]},    [r1,:128]
-        vld4.32         {d16[],d17[],d18[],d19[]},[r2,:128]!
-        paeth           d0,  d3,  d16, d20
-        vadd.u8         d0,  d0,  d4
-        paeth           d1,  d0,  d17, d16
-        vadd.u8         d1,  d1,  d5
-        paeth           d2,  d1,  d18, d17
-        vadd.u8         d2,  d2,  d6
-        paeth           d3,  d2,  d19, d18
-        vmov            d20, d19
-        vadd.u8         d3,  d3,  d7
-        vst4.32         {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
-        subs            r12, r12, #16
-        bgt             1b
-
-        bx              lr
-endfunc
-
-func    png_read_filter_row_paeth3_neon, export=1
-        push            {r4,lr}
-        ldr             r12, [r0, #4]           @ rowbytes
-        vmov.i8         d3,  #0
-        vmov.i8         d4,  #0
-        mov             r0,  r1
-        mov             r4,  #3
-        mov             lr,  #12
-        vld1.8          {q11},    [r0], lr
-1:
-        vld1.8          {q10},    [r2], lr
-        paeth           d0,  d3,  d20, d4
-        vext.8          d5,  d22, d23, #3
-        vadd.u8         d0,  d0,  d22
-        vext.8          d17, d20, d21, #3
-        paeth           d1,  d0,  d17, d20
-        vst1.32         {d0[0]},  [r1,:32], r4
-        vext.8          d6,  d22, d23, #6
-        vadd.u8         d1,  d1,  d5
-        vext.8          d18, d20, d21, #6
-        paeth           d2,  d1,  d18, d17
-        vext.8          d7,  d23, d23, #1
-        vld1.8          {q11},    [r0], lr
-        vst1.32         {d1[0]},  [r1], r4
-        vadd.u8         d2,  d2,  d6
-        vext.8          d19, d21, d21, #1
-        paeth           d3,  d2,  d19, d18
-        vst1.32         {d2[0]},  [r1], r4
-        vmov            d4,  d19
-        vadd.u8         d3,  d3,  d7
-        vst1.32         {d3[0]},  [r1], r4
-        subs            r12, r12, #12
-        bgt             1b
-
-        pop             {r4,pc}
-endfunc
 #endif /* PNG_ARM_NEON_OPT > 0 */
-#endif /* PNG_ARM_NEON_IMPLEMENTATION == 2 (assembler) */
+#endif /* PNG_ARM_NEON_IMPLEMENTATION == 2 */
 #endif /* READ */

arm/filter_neon_intrinsics.c

@@ -1,12 +1,10 @@
-
 /* filter_neon_intrinsics.c - NEON optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
  * Written by James Yu <james.yu at linaro.org>, October 2013.
  * Based on filter_neon.S, written by Mans Rullgard, 2011.
  *
- * Last changed in libpng 1.6.22 [May 26, 2016]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
@@ -19,7 +17,11 @@
 /* This code requires -mfpu=neon on the command line: */
 #if PNG_ARM_NEON_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
 
-#include <arm_neon.h>
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
+#  include <arm64_neon.h>
+#else
+#  include <arm_neon.h>
+#endif
 
 /* libpng row pointers are not necessarily aligned to any particular boundary,
  * however this code will only work with appropriate alignment.  arm/arm_init.c
@@ -33,6 +35,11 @@
  * 'type'.  This is written this way just to hide the GCC strict aliasing
  * warning; note that the code is safe because there never is an alias between
  * the input and output pointers.
+ *
+ * When compiling with MSVC ARM64, the png_ldr macro can't be passed directly
+ * to vst4_lane_u32, because of an internal compiler error inside MSVC.
+ * To avoid this compiler bug, we use a temporary variable (vdest_val) to store
+ * the result of png_ldr.
  */
 #define png_ldr(type,pointer)\
    (temp_pointer = png_ptr(type,pointer), *temp_pointer)
@@ -125,12 +132,15 @@ png_read_filter_row_sub4_neon(png_row_infop row_info, png_bytep row,
       uint8x8x4_t *vrpt = png_ptr(uint8x8x4_t,&vtmp);
       uint8x8x4_t vrp = *vrpt;
       uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
 
       vdest.val[0] = vadd_u8(vdest.val[3], vrp.val[0]);
       vdest.val[1] = vadd_u8(vdest.val[0], vrp.val[1]);
       vdest.val[2] = vadd_u8(vdest.val[1], vrp.val[2]);
       vdest.val[3] = vadd_u8(vdest.val[2], vrp.val[3]);
-      vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
    }
 
    PNG_UNUSED(prev_row)
@@ -223,6 +233,7 @@ png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
       uint8x8x4_t *vrpt, *vppt;
       uint8x8x4_t vrp, vpp;
       uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
 
       vtmp = vld4_u32(png_ptr(uint32_t,rp));
       vrpt = png_ptr(uint8x8x4_t,&vtmp);
@@ -240,7 +251,8 @@ png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
       vdest.val[3] = vhadd_u8(vdest.val[2], vpp.val[3]);
       vdest.val[3] = vadd_u8(vdest.val[3], vrp.val[3]);
 
-      vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
    }
 }
 
@@ -359,6 +371,7 @@ png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
       uint8x8x4_t *vrpt, *vppt;
       uint8x8x4_t vrp, vpp;
       uint32x2x4_t *temp_pointer;
+      uint32x2x4_t vdest_val;
 
       vtmp = vld4_u32(png_ptr(uint32_t,rp));
       vrpt = png_ptr(uint8x8x4_t,&vtmp);
@@ -378,7 +391,8 @@ png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
 
       vlast = vpp.val[3];
 
-      vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+      vdest_val = png_ldr(uint32x2x4_t, &vdest);
+      vst4_lane_u32(png_ptr(uint32_t,rp), vdest_val, 0);
    }
 }
 

arm/palette_neon_intrinsics.c

@@ -0,0 +1,150 @@
+/* palette_neon_intrinsics.c - NEON optimised palette expansion functions
+ *
+ * Copyright (c) 2018-2019 Cosmin Truta
+ * Copyright (c) 2017-2018 Arm Holdings. All rights reserved.
+ * Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "../pngpriv.h"
+
+#if PNG_ARM_NEON_IMPLEMENTATION == 1
+
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
+#  include <arm64_neon.h>
+#else
+#  include <arm_neon.h>
+#endif
+
+/* Build an RGBA8 palette from the separate RGB and alpha palettes. */
+void
+png_riffle_palette_neon(png_structrp png_ptr)
+{
+   png_const_colorp palette = png_ptr->palette;
+   png_bytep riffled_palette = png_ptr->riffled_palette;
+   png_const_bytep trans_alpha = png_ptr->trans_alpha;
+   int num_trans = png_ptr->num_trans;
+   int i;
+
+   /* Initially black, opaque. */
+   uint8x16x4_t w = {{
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0xff),
+   }};
+
+   png_debug(1, "in png_riffle_palette_neon");
+
+   /* First, riffle the RGB colours into an RGBA8 palette.
+    * The alpha component is set to opaque for now.
+    */
+   for (i = 0; i < 256; i += 16)
+   {
+      uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
+      w.val[0] = v.val[0];
+      w.val[1] = v.val[1];
+      w.val[2] = v.val[2];
+      vst4q_u8(riffled_palette + (i << 2), w);
+   }
+
+   /* Fix up the missing transparency values. */
+   for (i = 0; i < num_trans; i++)
+      riffled_palette[(i << 2) + 3] = trans_alpha[i];
+}
+
+/* Expands a palettized row into RGBA8. */
+int
+png_do_expand_palette_rgba8_neon(png_structrp png_ptr, png_row_infop row_info,
+    png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
+{
+   png_uint_32 row_width = row_info->width;
+   const png_uint_32 *riffled_palette =
+      png_aligncastconst(png_const_uint_32p, png_ptr->riffled_palette);
+   const png_uint_32 pixels_per_chunk = 4;
+   png_uint_32 i;
+
+   png_debug(1, "in png_do_expand_palette_rgba8_neon");
+
+   PNG_UNUSED(row)
+   if (row_width < pixels_per_chunk)
+      return 0;
+
+   /* This function originally gets the last byte of the output row.
+    * The NEON part writes forward from a given position, so we have
+    * to seek this back by 4 pixels x 4 bytes.
+    */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
+
+   for (i = 0; i < row_width; i += pixels_per_chunk)
+   {
+      uint32x4_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
+      cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
+      vst1q_u32((void *)dp, cur);
+   }
+   if (i != row_width)
+   {
+      /* Remove the amount that wasn't processed. */
+      i -= pixels_per_chunk;
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - (i << 2);
+   return i;
+}
+
+/* Expands a palettized row into RGB8. */
+int
+png_do_expand_palette_rgb8_neon(png_structrp png_ptr, png_row_infop row_info,
+    png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
+{
+   png_uint_32 row_width = row_info->width;
+   png_const_bytep palette = (png_const_bytep)png_ptr->palette;
+   const png_uint_32 pixels_per_chunk = 8;
+   png_uint_32 i;
+
+   png_debug(1, "in png_do_expand_palette_rgb8_neon");
+
+   PNG_UNUSED(row)
+   if (row_width <= pixels_per_chunk)
+      return 0;
+
+   /* Seeking this back by 8 pixels x 3 bytes. */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
+
+   for (i = 0; i < row_width; i += pixels_per_chunk)
+   {
+      uint8x8x3_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
+      cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
+      vst3_u8((void *)dp, cur);
+   }
+
+   if (i != row_width)
+   {
+      /* Remove the amount that wasn't processed. */
+      i -= pixels_per_chunk;
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - ((i << 1) + i);
+   return i;
+}
+
+#endif /* PNG_ARM_NEON_IMPLEMENTATION */

autogen.sh

@@ -77,13 +77,14 @@ libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
    config.sub configure depcomp install-sh ltmain.sh missing\
    test-driver"
 #
-# Files generated by versions of configue >2.68 or automake >1.13 (i.e. later
+# Files generated by versions of autoconf >2.68 or automake >1.13 (i.e. later
 # versions than those required by configure.ac):
 libpng_autotools_extra="compile config.h.in~"
 #
 # These are separate because 'maintainer-clean' does not remove them.
-libpng_libtool_files="scripts/libtool.m4 scripts/ltoptions.m4\
+libpng_libtool_files="scripts/autoconf/libtool.m4 scripts/autoconf/ltoptions.m4\
-   scripts/ltsugar.m4 scripts/ltversion.m4 scripts/lt~obsolete.m4"
+   scripts/autoconf/ltsugar.m4 scripts/autoconf/ltversion.m4\
+   scripts/autoconf/lt~obsolete.m4"
 
 libpng_autotools_dirs="autom4te.cache" # not required
 #

ci/.shellcheckrc

@@ -0,0 +1,11 @@
+# Disable the "expressions don't expand in single quotes, use double quotes"
+# advice. We need the regular expressions to remain uninterpolated.
+disable=SC2016
+
+# Disable the "variable appears unused" warning caused by the use of getopts
+# with an obligatory (but unused) variable name in the main function.
+disable=SC2034
+
+# Disable all the "quote to prevent globbing or word splitting" advice.
+# We need word splitting for well-known variables like MAKEFLAGS and CFLAGS.
+disable=SC2086,SC2206

ci/LICENSE_MIT.txt

@@ -0,0 +1,19 @@
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

ci/README.md

@@ -0,0 +1,25 @@
+Scripts for the Continuous Integration of the PNG Reference Library
+===================================================================
+
+Copyright Notice
+----------------
+
+Copyright (c) 2019-2025 Cosmin Truta.
+
+Use, modification and distribution are subject to the MIT License.
+Please see the accompanying file `LICENSE_MIT.txt` or visit
+https://opensource.org/license/mit
+
+File List
+---------
+
+    LICENSE_MIT.txt         ==>  The License file
+    README.md               ==>  This file
+    ci_lint.sh              ==>  Lint the source code
+    ci_shellify.sh          ==>  Convert select definitions to shell syntax
+    ci_verify_cmake.sh      ==>  Verify the build driven by CMakeLists.txt
+    ci_verify_configure.sh  ==>  Verify the build driven by configure
+    ci_verify_makefiles.sh  ==>  Verify the build driven by scripts/makefile.*
+    ci_verify_version.sh    ==>  Verify the consistency of version definitions
+    lib/ci.lib.sh           ==>  Shell utilities for the main ci_*.sh scripts
+    targets/*/ci_env.*.sh   ==>  Shell environments for cross-platform testing

ci/ci_lint.sh

@@ -0,0 +1,142 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+# Initialize the global constants CI_{...}{CHECK,CHECKER,LINT}.
+CI_SHELLCHECK="${CI_SHELLCHECK:-shellcheck}"
+CI_EDITORCONFIG_CHECKER="${CI_EDITORCONFIG_CHECKER:-editorconfig-checker}"
+CI_YAMLLINT="${CI_YAMLLINT:-yamllint}"
+
+# Initialize the global lint status.
+CI_LINT_STATUS=0
+
+function ci_init_lint {
+    ci_info "## START OF LINTING ##"
+    local my_program
+    # Complete the initialization of CI_SHELLCHECK.
+    # Set it to the empty string if the shellcheck program is unavailable.
+    my_program="$(command -v "$CI_SHELLCHECK")" || {
+        ci_warn "program not found: '$CI_SHELLCHECK'"
+    }
+    CI_SHELLCHECK="$my_program"
+    # Complete the initialization of CI_EDITORCONFIG_CHECKER.
+    # Set it to the empty string if the editorconfig-checker program is unavailable.
+    my_program="$(command -v "$CI_EDITORCONFIG_CHECKER")" || {
+        ci_warn "program not found: '$CI_EDITORCONFIG_CHECKER'"
+    }
+    CI_EDITORCONFIG_CHECKER="$my_program"
+    # Complete the initialization of CI_YAMLLINT.
+    # Set it to the empty string if the yamllint program is unavailable.
+    my_program="$(command -v "$CI_YAMLLINT")" || {
+        ci_warn "program not found: '$CI_YAMLLINT'"
+    }
+    CI_YAMLLINT="$my_program"
+}
+
+function ci_finish_lint {
+    ci_info "## END OF LINTING ##"
+    if [[ $CI_LINT_STATUS -eq 0 ]]
+    then
+        ci_info "## SUCCESS ##"
+    else
+        ci_info "linting failed"
+    fi
+    return "$CI_LINT_STATUS"
+}
+
+function ci_lint_ci_scripts {
+    [[ -x $CI_SHELLCHECK ]] || {
+        ci_warn "## NOT LINTING: CI scripts ##"
+        return 0
+    }
+    ci_info "## LINTING: CI scripts ##"
+    ci_spawn "$CI_SHELLCHECK" --version
+    find ./ci -name "ci_*.sh" -not -name "ci_env.*.sh" | {
+        local my_file
+        while IFS="" read -r my_file
+        do
+            ci_spawn "$CI_SHELLCHECK" -x "$my_file" || {
+                # Linting failed.
+                return 1
+            }
+        done
+    }
+}
+
+function ci_lint_text_files {
+    [[ -x $CI_EDITORCONFIG_CHECKER ]] || {
+        ci_warn "## NOT LINTING: text files ##"
+        return 0
+    }
+    ci_info "## LINTING: text files ##"
+    ci_spawn "$CI_EDITORCONFIG_CHECKER" --version
+    ci_spawn "$CI_EDITORCONFIG_CHECKER" --config .editorconfig-checker.json || {
+        # Linting failed.
+        return 1
+    }
+}
+
+function ci_lint_yaml_files {
+    [[ -x $CI_YAMLLINT ]] || {
+        ci_warn "## NOT LINTING: YAML files ##"
+        return 0
+    }
+    ci_info "## LINTING: YAML files ##"
+    ci_spawn "$CI_YAMLLINT" --version
+    # Considering that the YAML format is an extension of the JSON format,
+    # we can lint both the YAML files and the plain JSON files here.
+    find . \( -iname "*.yml" -o -iname "*.yaml" -o -iname "*.json" \) -not -path "./out/*" | {
+        local my_file
+        while IFS="" read -r my_file
+        do
+            ci_spawn "$CI_YAMLLINT" --strict "$my_file" || {
+                # Linting failed.
+                return 1
+            }
+        done
+    }
+}
+
+function ci_lint {
+    ci_init_lint
+    ci_lint_ci_scripts || CI_LINT_STATUS=1
+    ci_lint_text_files || CI_LINT_STATUS=1
+    ci_lint_yaml_files || CI_LINT_STATUS=1
+    # TODO: ci_lint_png_files, etc.
+    ci_finish_lint
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        usage 2
+    }
+    # And... go!
+    ci_lint
+}
+
+main "$@"

ci/ci_verify_cmake.sh

@@ -0,0 +1,209 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+CI_OUT_DIR="$CI_TOPLEVEL_DIR/out"
+CI_BUILD_DIR="$CI_OUT_DIR/ci_verify_cmake.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.build"
+CI_INSTALL_DIR="$CI_OUT_DIR/ci_verify_cmake.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.install"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_CMAKE="${CI_CMAKE:-cmake}"
+    CI_CTEST="${CI_CTEST:-ctest}"
+    CI_CMAKE_BUILD_TYPE="${CI_CMAKE_BUILD_TYPE:-Release}"
+    if [[ $CI_CMAKE_GENERATOR == "Visual Studio"* ]]
+    then
+        # Clean up incidental mixtures of Windows and Bash-on-Windows
+        # environment variables, to avoid confusing MSBuild.
+        [[ $TEMP && ( $Temp || $temp ) ]] && unset TEMP
+        [[ $TMP && ( $Tmp || $tmp ) ]] && unset TMP
+        # Ensure that CI_CMAKE_GENERATOR_PLATFORM is initialized for this generator.
+        [[ $CI_CMAKE_GENERATOR_PLATFORM ]] || {
+            ci_err_internal "missing \$CI_CMAKE_GENERATOR_PLATFORM"
+        }
+    elif [[ -x $(command -v ninja) ]]
+    then
+        CI_CMAKE_GENERATOR="${CI_CMAKE_GENERATOR:-Ninja}"
+    fi
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "build directory: $CI_BUILD_DIR"
+    ci_info "install directory: $CI_INSTALL_DIR"
+    ci_info "environment option: \$CI_CMAKE: '$CI_CMAKE'"
+    ci_info "environment option: \$CI_CMAKE_GENERATOR: '$CI_CMAKE_GENERATOR'"
+    ci_info "environment option: \$CI_CMAKE_GENERATOR_PLATFORM: '$CI_CMAKE_GENERATOR_PLATFORM'"
+    ci_info "environment option: \$CI_CMAKE_BUILD_TYPE: '$CI_CMAKE_BUILD_TYPE'"
+    ci_info "environment option: \$CI_CMAKE_BUILD_FLAGS: '$CI_CMAKE_BUILD_FLAGS'"
+    ci_info "environment option: \$CI_CMAKE_TOOLCHAIN_FILE: '$CI_CMAKE_TOOLCHAIN_FILE'"
+    ci_info "environment option: \$CI_CMAKE_VARS: '$CI_CMAKE_VARS'"
+    ci_info "environment option: \$CI_CTEST: '$CI_CTEST'"
+    ci_info "environment option: \$CI_CTEST_FLAGS: '$CI_CTEST_FLAGS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_CMAKE: $(command -V "$CI_CMAKE")"
+    ci_info "executable: \$CI_CTEST: $(command -V "$CI_CTEST")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    [[ ! -e $CI_BUILD_DIR && ! -e $CI_INSTALL_DIR ]] || {
+        ci_spawn rm -fr "$CI_BUILD_DIR"
+        ci_spawn rm -fr "$CI_INSTALL_DIR"
+    }
+    ci_info "## END OF PRE-BUILD CLEANUP ##"
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Adjust the CI environment variables, as needed.
+    CI_CMAKE="$(command -v "$CI_CMAKE")" || ci_err "bad or missing \$CI_CMAKE"
+    ci_spawn "$CI_CMAKE" --version
+    CI_CTEST="$(command -v "$CI_CTEST")" || ci_err "bad or missing \$CI_CTEST"
+    ci_spawn "$CI_CTEST" --version
+    [[ $CI_CMAKE_GENERATOR == *"Ninja"* ]] && {
+        CI_NINJA="$(command -v ninja)" || ci_err "bad or missing ninja, no pun intended"
+        ci_spawn "$CI_NINJA" --version
+    }
+    [[ $CI_AR ]] && {
+        # Use the full path of CI_AR to work around a mysterious CMake error.
+        CI_AR="$(command -v "$CI_AR")" || ci_err "bad or missing \$CI_AR"
+    }
+    [[ $CI_RANLIB ]] && {
+        # Use the full path of CI_RANLIB to work around a mysterious CMake error.
+        CI_RANLIB="$(command -v "$CI_RANLIB")" || ci_err "bad or missing \$CI_RANLIB"
+    }
+    # Export the CMake environment variables.
+    [[ $CI_CMAKE_GENERATOR ]] && {
+        ci_spawn export CMAKE_GENERATOR="$CI_CMAKE_GENERATOR"
+    }
+    [[ $CI_CMAKE_GENERATOR_PLATFORM ]] && {
+        ci_spawn export CMAKE_GENERATOR_PLATFORM="$CI_CMAKE_GENERATOR_PLATFORM"
+    }
+    # Initialize and populate the local arrays.
+    local all_cmake_vars=()
+    local all_cmake_build_flags=()
+    local all_ctest_flags=()
+    [[ $CI_CMAKE_TOOLCHAIN_FILE ]] && {
+        all_cmake_vars+=("-DCMAKE_TOOLCHAIN_FILE=$CI_CMAKE_TOOLCHAIN_FILE")
+    }
+    [[ $CI_CC ]] && {
+        all_cmake_vars+=("-DCMAKE_C_COMPILER=$CI_CC")
+    }
+    [[ $CI_CC_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_CC_FLAGS+="${CI_CC_FLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+        all_cmake_vars+=("-DCMAKE_C_FLAGS=$CI_CC_FLAGS")
+    }
+    [[ $CI_AR ]] && {
+        all_cmake_vars+=("-DCMAKE_AR=$CI_AR")
+    }
+    [[ $CI_RANLIB ]] && {
+        all_cmake_vars+=("-DCMAKE_RANLIB=$CI_RANLIB")
+    }
+    all_cmake_vars+=("-DCMAKE_BUILD_TYPE=$CI_CMAKE_BUILD_TYPE")
+    all_cmake_vars+=("-DCMAKE_VERBOSE_MAKEFILE=ON")
+    all_cmake_vars+=($CI_CMAKE_VARS)
+    all_cmake_build_flags+=($CI_CMAKE_BUILD_FLAGS)
+    all_ctest_flags+=($CI_CTEST_FLAGS)
+    # And... build!
+    ci_spawn mkdir -p "$CI_BUILD_DIR"
+    # Spawn "cmake ...".
+    ci_spawn "$CI_CMAKE" -B "$CI_BUILD_DIR" \
+                         -S . \
+                         -DCMAKE_INSTALL_PREFIX="$CI_INSTALL_DIR" \
+                         "${all_cmake_vars[@]}"
+    ci_expr $((CI_NO_BUILD)) || {
+        # Spawn "cmake --build ...".
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_expr $((CI_NO_TEST)) || {
+        # Spawn "ctest" if testing is not disabled.
+        ci_spawn pushd "$CI_BUILD_DIR"
+        ci_spawn "$CI_CTEST" --build-config "$CI_CMAKE_BUILD_TYPE" \
+                             "${all_ctest_flags[@]}"
+        ci_spawn popd
+    }
+    ci_expr $((CI_NO_INSTALL)) || {
+        # Spawn "cmake --build ... --target install" if installation is not disabled.
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             --target install \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_expr $((CI_NO_CLEAN)) || {
+        # Spawn "make --build ... --target clean" if cleaning is not disabled.
+        ci_spawn "$CI_CMAKE" --build "$CI_BUILD_DIR" \
+                             --config "$CI_CMAKE_BUILD_TYPE" \
+                             --target clean \
+                             "${all_cmake_build_flags[@]}"
+    }
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_configure.sh

@@ -0,0 +1,182 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+CI_OUT_DIR="$CI_TOPLEVEL_DIR/out"
+CI_BUILD_DIR="$CI_OUT_DIR/ci_verify_configure.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.build"
+CI_INSTALL_DIR="$CI_OUT_DIR/ci_verify_configure.$CI_TARGET_SYSTEM.$CI_TARGET_ARCH.install"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_MAKE="${CI_MAKE:-make}"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] || {
+        # For native builds, set CI_CC to "cc" by default if the cc command is available.
+        # The configure script defaults CC to "gcc", which is not always a good idea.
+        [[ -x $(command -v cc) ]] && CI_CC="${CI_CC:-cc}"
+    }
+    # Ensure that the CI_ variables that cannot be customized reliably are not initialized.
+    [[ ! $CI_CONFIGURE_VARS ]] || {
+        ci_err "unsupported: \$CI_CONFIGURE_VARS='$CI_CONFIGURE_VARS'"
+    }
+    [[ ! $CI_MAKE_VARS ]] || {
+        ci_err "unsupported: \$CI_MAKE_VARS='$CI_MAKE_VARS'"
+    }
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "build directory: $CI_BUILD_DIR"
+    ci_info "install directory: $CI_INSTALL_DIR"
+    ci_info "environment option: \$CI_CONFIGURE_FLAGS: '$CI_CONFIGURE_FLAGS'"
+    ci_info "environment option: \$CI_MAKE: '$CI_MAKE'"
+    ci_info "environment option: \$CI_MAKE_FLAGS: '$CI_MAKE_FLAGS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_CPP: '$CI_CPP'"
+    ci_info "environment option: \$CI_CPP_FLAGS: '$CI_CPP_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_LD: '$CI_LD'"
+    ci_info "environment option: \$CI_LD_FLAGS: '$CI_LD_FLAGS'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_MAKE: $(command -V "$CI_MAKE")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_CPP ]] && {
+        ci_info "executable: \$CI_CPP: $(command -V "$CI_CPP")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    [[ $CI_LD ]] && {
+        ci_info "executable: \$CI_LD: $(command -V "$CI_LD")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    [[ ! -e $CI_BUILD_DIR && ! -e $CI_INSTALL_DIR ]] || {
+        ci_spawn rm -fr "$CI_BUILD_DIR"
+        ci_spawn rm -fr "$CI_INSTALL_DIR"
+    }
+    [[ ! -e "$CI_SRC_DIR/config.status" ]] || {
+        ci_warn "unexpected build configuration file: '$CI_SRC_DIR/config.status'"
+        if ci_expr $((CI_FORCE))
+        then
+            # Delete the old config and (possibly) the old build.
+            ci_info "note: forcing an in-tree build cleanup"
+            if [[ -f $CI_SRC_DIR/Makefile ]]
+            then
+                ci_spawn make -C "$CI_SRC_DIR" distclean
+            else
+                ci_spawn rm -fr "$CI_SRC_DIR"/config.{log,status}
+            fi
+        else
+            # Alert the user, but do not delete their files.
+            ci_warn "the configure script might fail"
+            ci_info "hint: consider using the option \$CI_FORCE=1"
+        fi
+    }
+    ci_info "## END OF PRE-BUILD CLEANUP ##"
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Export the configure build environment.
+    [[ $CI_CC ]] && ci_spawn export CC="$CI_CC"
+    [[ $CI_CC_FLAGS ]] && ci_spawn export CFLAGS="$CI_CC_FLAGS"
+    [[ $CI_CPP ]] && ci_spawn export CPP="$CI_CPP"
+    [[ $CI_CPP_FLAGS ]] && ci_spawn export CPPFLAGS="$CI_CPP_FLAGS"
+    [[ $CI_AR ]] && ci_spawn export AR="$CI_AR"
+    [[ $CI_RANLIB ]] && ci_spawn export RANLIB="$CI_RANLIB"
+    [[ $CI_LD ]] && ci_spawn export LD="$CI_LD"
+    [[ $CI_LD_FLAGS ]] && ci_spawn export LDFLAGS="$CI_LD_FLAGS"
+    [[ $CI_SANITIZERS ]] && {
+        ci_spawn export CFLAGS="${CFLAGS:-"-O2"} -fsanitize=$CI_SANITIZERS"
+        ci_spawn export LDFLAGS="${LDFLAGS}${LDFLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+    }
+    # Spawn "autogen.sh" if the configure script is not available.
+    [[ -x "$CI_SRC_DIR/configure" ]] || {
+        ci_spawn "$CI_SRC_DIR/autogen.sh" --maintainer
+    }
+    # And... build!
+    ci_spawn mkdir -p "$CI_BUILD_DIR"
+    ci_spawn cd "$CI_BUILD_DIR"
+    # Spawn "configure".
+    ci_spawn "$CI_SRC_DIR/configure" --prefix="$CI_INSTALL_DIR" $CI_CONFIGURE_FLAGS
+    ci_expr $((CI_NO_BUILD)) || {
+        # Spawn "make".
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS
+    }
+    ci_expr $((CI_NO_TEST)) || {
+        # Spawn "make test" if testing is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS test
+    }
+    ci_expr $((CI_NO_INSTALL)) || {
+        # Spawn "make install" if installation is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS install
+    }
+    ci_expr $((CI_NO_CLEAN)) || {
+        # Spawn "make clean" and "make distclean" if cleaning is not disabled.
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS clean
+        ci_spawn "$CI_MAKE" $CI_MAKE_FLAGS distclean
+    }
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_makefiles.sh

@@ -0,0 +1,200 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+CI_SRC_DIR="$CI_TOPLEVEL_DIR"
+
+function ci_init_build {
+    # Ensure that the mandatory variables are initialized.
+    CI_MAKE="${CI_MAKE:-make}"
+    case "$CI_CC" in
+    ( *clang* )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.clang"}" ;;
+    ( *gcc* )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.gcc"}" ;;
+    ( * )
+        CI_MAKEFILES="${CI_MAKEFILES:-"scripts/makefile.std"}" ;;
+    esac
+}
+
+function ci_trace_build {
+    ci_info "## START OF CONFIGURATION ##"
+    ci_info "build arch: $CI_BUILD_ARCH"
+    ci_info "build system: $CI_BUILD_SYSTEM"
+    [[ "$CI_TARGET_SYSTEM.$CI_TARGET_ARCH" != "$CI_BUILD_SYSTEM.$CI_BUILD_ARCH" ]] && {
+        ci_info "target arch: $CI_TARGET_ARCH"
+        ci_info "target system: $CI_TARGET_SYSTEM"
+    }
+    ci_info "source directory: $CI_SRC_DIR"
+    ci_info "environment option: \$CI_MAKEFILES: '$CI_MAKEFILES'"
+    ci_info "environment option: \$CI_MAKE: '$CI_MAKE'"
+    ci_info "environment option: \$CI_MAKE_FLAGS: '$CI_MAKE_FLAGS'"
+    ci_info "environment option: \$CI_MAKE_VARS: '$CI_MAKE_VARS'"
+    ci_info "environment option: \$CI_CC: '$CI_CC'"
+    ci_info "environment option: \$CI_CC_FLAGS: '$CI_CC_FLAGS'"
+    ci_info "environment option: \$CI_CPP: '$CI_CPP'"
+    ci_info "environment option: \$CI_CPP_FLAGS: '$CI_CPP_FLAGS'"
+    ci_info "environment option: \$CI_AR: '$CI_AR'"
+    ci_info "environment option: \$CI_RANLIB: '$CI_RANLIB'"
+    ci_info "environment option: \$CI_LD: '$CI_LD'"
+    ci_info "environment option: \$CI_LD_FLAGS: '$CI_LD_FLAGS'"
+    ci_info "environment option: \$CI_LIBS: '$CI_LIBS'"
+    ci_info "environment option: \$CI_SANITIZERS: '$CI_SANITIZERS'"
+    ci_info "environment option: \$CI_FORCE: '$CI_FORCE'"
+    ci_info "environment option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+    ci_info "environment option: \$CI_NO_TEST: '$CI_NO_TEST'"
+    ci_info "environment option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+    ci_info "executable: \$CI_MAKE: $(command -V "$CI_MAKE")"
+    [[ $CI_CC ]] && {
+        ci_info "executable: \$CI_CC: $(command -V "$CI_CC")"
+    }
+    [[ $CI_CPP ]] && {
+        ci_info "executable: \$CI_CPP: $(command -V "$CI_CPP")"
+    }
+    [[ $CI_AR ]] && {
+        ci_info "executable: \$CI_AR: $(command -V "$CI_AR")"
+    }
+    [[ $CI_RANLIB ]] && {
+        ci_info "executable: \$CI_RANLIB: $(command -V "$CI_RANLIB")"
+    }
+    [[ $CI_LD ]] && {
+        ci_info "executable: \$CI_LD: $(command -V "$CI_LD")"
+    }
+    ci_info "## END OF CONFIGURATION ##"
+}
+
+function ci_cleanup_old_build {
+    # Any old makefile-based build will most likely leave a mess
+    # of object files behind if interrupted, e.g., via Ctrl+C.
+    # There may be other files behind, depending on what makefile
+    # had been used. We cannot easily enumerate all of those.
+    # Fortunately, for a clean makefiles-based build, it should be
+    # sufficient to remove the old object files only.
+    ci_info "## START OF PRE-BUILD CLEANUP ##"
+    local find_args=(-maxdepth 1 \( -iname "*.o" -o -iname "*.obj" \))
+    [[ ! $(find "$CI_SRC_DIR" "${find_args[@]}" | head -n1) ]] || {
+        ci_warn "unexpected build found in '$CI_SRC_DIR'"
+        if ci_expr $((CI_FORCE))
+        then
+            # Delete the old build.
+            local my_file
+            find "$CI_SRC_DIR" "${find_args[@]}" |
+                while IFS="" read -r my_file
+                do
+                    ci_spawn rm -fr "$my_file"
+                done
+            ci_info "## END OF PRE-BUILD CLEANUP ##"
+        else
+            # Alert the user, but do not delete their existing files,
+            # and do not mess up their existing build.
+            ci_info "hint: consider using the option \$CI_FORCE=1"
+            ci_err "unable to continue"
+        fi
+    }
+}
+
+function ci_build {
+    ci_info "## START OF BUILD ##"
+    # Initialize and populate the local arrays.
+    local all_make_flags=()
+    local all_make_vars=()
+    [[ $CI_MAKE_FLAGS ]] && {
+        all_make_flags+=($CI_MAKE_FLAGS)
+    }
+    [[ $CI_CC ]] && {
+        all_make_vars+=("CC=$CI_CC")
+    }
+    [[ $CI_CC_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_CC_FLAGS="${CI_CC_FLAGS:-"-O2"} -fsanitize=$CI_SANITIZERS"
+        all_make_vars+=("CFLAGS=$CI_CC_FLAGS")
+    }
+    [[ $CI_CPP ]] && {
+        all_make_vars+=("CPP=$CI_CPP")
+    }
+    [[ $CI_CPP_FLAGS ]] && {
+        all_make_vars+=("CPPFLAGS=$CI_CPP_FLAGS")
+    }
+    [[ $CI_AR ]] && {
+        all_make_vars+=("AR=$CI_AR")
+    }
+    [[ $CI_RANLIB ]] && {
+        all_make_vars+=("RANLIB=$CI_RANLIB")
+    }
+    [[ $CI_LD ]] && {
+        all_make_vars+=("LD=$CI_LD")
+    }
+    [[ $CI_LD_FLAGS || $CI_SANITIZERS ]] && {
+        [[ $CI_SANITIZERS ]] && CI_LD_FLAGS+="${CI_LD_FLAGS:+" "}-fsanitize=$CI_SANITIZERS"
+        all_make_vars+=("LDFLAGS=$CI_LD_FLAGS")
+    }
+    [[ $CI_LIBS ]] && {
+        all_make_vars+=("LIBS=$CI_LIBS")
+    }
+    all_make_vars+=($CI_MAKE_VARS)
+    # And... build!
+    local my_makefile
+    for my_makefile in $CI_MAKEFILES
+    do
+        ci_info "using makefile: $my_makefile"
+        ci_expr $((CI_NO_BUILD)) || {
+            # Spawn "make".
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}"
+        }
+        ci_expr $((CI_NO_TEST)) || {
+            # Spawn "make test" if testing is not disabled.
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}" \
+                                test
+        }
+        ci_expr $((CI_NO_CLEAN)) || {
+            # Spawn "make clean" if cleaning is not disabled.
+            ci_spawn "$CI_MAKE" -f "$my_makefile" \
+                                "${all_make_flags[@]}" \
+                                "${all_make_vars[@]}" \
+                                clean
+        }
+    done
+    ci_info "## END OF BUILD ##"
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    ci_init_build
+    ci_trace_build
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        echo >&2 "note: this program accepts environment options only"
+        usage 2
+    }
+    ci_cleanup_old_build
+    ci_build
+}
+
+main "$@"

ci/ci_verify_version.sh

@@ -0,0 +1,191 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/lib/ci.lib.sh"
+cd "$CI_TOPLEVEL_DIR"
+
+# Declare the global environments collected from various sources.
+declare CI_ENV_LIBPNG_VER        # collected from png.h
+declare CI_ENV_AUTOCONF_VER      # collected from configure.ac
+declare CI_ENV_CMAKE_VER         # collected from CMakeLists.txt
+declare CI_ENV_LIBPNGCONFIG_VER  # collected from scripts/libpng-config-head.in
+
+function ci_run_shellify {
+    local my_script my_result
+    my_script="$CI_SCRIPT_DIR/libexec/ci_shellify_${1#--}.sh"
+    shift 1
+    [[ -f $my_script ]] || {
+        ci_err_internal "missing script: '$my_script'"
+    }
+    ci_info "shellifying:" "$@"
+    "$BASH" "$my_script" "$@"
+    echo "$my_result" | "$BASH" --posix || ci_err "bad shellify output"
+    echo "$my_result"
+}
+
+function ci_init_version_verification {
+    ci_info "## START OF VERIFICATION ##"
+    CI_ENV_LIBPNG_VER="$(ci_run_shellify --c png.h)"
+    echo "$CI_ENV_LIBPNG_VER"
+    CI_ENV_AUTOCONF_VER="$(ci_run_shellify --autoconf configure.ac)"
+    echo "$CI_ENV_AUTOCONF_VER"
+    CI_ENV_CMAKE_VER="$(ci_run_shellify --cmake CMakeLists.txt)"
+    echo "$CI_ENV_CMAKE_VER"
+    CI_ENV_LIBPNGCONFIG_VER="$(ci_run_shellify --shell scripts/libpng-config-head.in)"
+    echo "$CI_ENV_LIBPNGCONFIG_VER"
+}
+
+# shellcheck disable=SC2154
+function ci_do_version_verification {
+    local my_expect
+    ci_info "## VERIFYING: version definitions in 'png.h' ##"
+    eval "$CI_ENV_LIBPNG_VER"
+    my_expect="${PNG_LIBPNG_VER_MAJOR}.${PNG_LIBPNG_VER_MINOR}.${PNG_LIBPNG_VER_RELEASE}"
+    if [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect"* ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_STRING == $my_expect*"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_STRING != $my_expect*"
+    fi
+    my_expect=$((PNG_LIBPNG_VER_MAJOR*10000 + PNG_LIBPNG_VER_MINOR*100 + PNG_LIBPNG_VER_RELEASE))
+    if [[ "$PNG_LIBPNG_VER" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER != $my_expect"
+    fi
+    my_expect=$((PNG_LIBPNG_VER_MAJOR*10 + PNG_LIBPNG_VER_MINOR))
+    if [[ "$PNG_LIBPNG_VER_SHAREDLIB" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_SHAREDLIB == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_SHAREDLIB != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_SONUM" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_SONUM == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_SONUM != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_DLLNUM" == "$my_expect" ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_DLLNUM == $my_expect"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_DLLNUM != $my_expect"
+    fi
+    if [[ "$PNG_LIBPNG_VER_BUILD" == [01] ]]
+    then
+        ci_info "matched: \$PNG_LIBPNG_VER_BUILD == [01]"
+    else
+        ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD != [01]"
+    fi
+    ci_info "## VERIFYING: build definitions in 'png.h' ##"
+    my_expect="${PNG_LIBPNG_VER_MAJOR}.${PNG_LIBPNG_VER_MINOR}.${PNG_LIBPNG_VER_RELEASE}"
+    if [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect" ]]
+    then
+        if [[ $PNG_LIBPNG_VER_BUILD -eq 0 ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_VER_BUILD -eq 0"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD -ne 0"
+        fi
+        if [[ $PNG_LIBPNG_BUILD_BASE_TYPE -eq $PNG_LIBPNG_BUILD_STABLE ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_BUILD_BASE_TYPE -eq \$PNG_LIBPNG_BUILD_STABLE"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_BUILD_BASE_TYPE -ne \$PNG_LIBPNG_BUILD_STABLE"
+        fi
+    elif [[ "$PNG_LIBPNG_VER_STRING" == "$my_expect".git ]]
+    then
+        if [[ $PNG_LIBPNG_VER_BUILD -ne 0 ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_VER_BUILD -ne 0"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_VER_BUILD -eq 0"
+        fi
+        if [[ $PNG_LIBPNG_BUILD_BASE_TYPE -ne $PNG_LIBPNG_BUILD_STABLE ]]
+        then
+            ci_info "matched: \$PNG_LIBPNG_BUILD_BASE_TYPE -ne \$PNG_LIBPNG_BUILD_STABLE"
+        else
+            ci_err "mismatched: \$PNG_LIBPNG_BUILD_BASE_TYPE -eq \$PNG_LIBPNG_BUILD_STABLE"
+        fi
+    else
+        ci_err "unexpected: \$PNG_LIBPNG_VER_STRING == '$PNG_LIBPNG_VER_STRING'"
+    fi
+    ci_info "## VERIFYING: type definitions in 'png.h' ##"
+    my_expect="$(echo "png_libpng_version_${PNG_LIBPNG_VER_STRING}" | tr . _)"
+    ci_spawn grep -w -e "$my_expect" png.h
+    ci_info "## VERIFYING: version definitions in 'configure.ac' ##"
+    eval "$CI_ENV_AUTOCONF_VER"
+    if [[ "$PNGLIB_VERSION" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$PNGLIB_VERSION != \$PNG_LIBPNG_VER_STRING"
+    fi
+    ci_info "## VERIFYING: version definitions in 'CMakeLists.txt' ##"
+    eval "$CI_ENV_CMAKE_VER"
+    if [[ "$PNGLIB_VERSION" == "$PNG_LIBPNG_VER_STRING" && "$PNGLIB_SUBREVISION" == 0 ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION == \$PNG_LIBPNG_VER_STRING"
+        ci_info "matched: \$PNGLIB_SUBREVISION == 0"
+    elif [[ "$PNGLIB_VERSION.$PNGLIB_SUBREVISION" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$PNGLIB_VERSION.\$PNGLIB_SUBREVISION == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$PNGLIB_VERSION != \$PNG_LIBPNG_VER_STRING"
+    fi
+    ci_info "## VERIFYING: version definitions in 'scripts/libpng-config-head.in' ##"
+    eval "$CI_ENV_LIBPNGCONFIG_VER"
+    if [[ "$version" == "$PNG_LIBPNG_VER_STRING" ]]
+    then
+        ci_info "matched: \$version == \$PNG_LIBPNG_VER_STRING"
+    else
+        ci_err "mismatched: \$version != \$PNG_LIBPNG_VER_STRING"
+    fi
+}
+
+function ci_finish_version_verification {
+    ci_info "## END OF VERIFICATION ##"
+    # Relying on "set -o errexit" to not reach here in case of error.
+    ci_info "## SUCCESS ##"
+}
+
+function ci_verify_version {
+    ci_init_version_verification
+    ci_do_version_verification
+    ci_finish_version_verification
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>]"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] || {
+        echo >&2 "error: unexpected argument: '$1'"
+        usage 2
+    }
+    # And... go!
+    ci_verify_version
+}
+
+main "$@"

ci/lib/ci.lib.sh

@@ -0,0 +1,111 @@
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+test -f "$BASH_SOURCE" || {
+    echo >&2 "warning: this module requires Bash version 3 or newer"
+}
+test "${#BASH_SOURCE[@]}" -gt 1 || {
+    echo >&2 "warning: this module should be sourced from a Bash script"
+}
+
+# Reset the locale to avoid surprises from locale-dependent commands.
+export LC_ALL=C
+export LANG=C
+export LANGUAGE=C
+
+# Reset CDPATH to avoid surprises from the "cd" command.
+export CDPATH=""
+
+# Initialize the global constants CI_SCRIPT_{NAME,DIR} and CI_TOPLEVEL_DIR.
+CI_SCRIPT_NAME="$(basename -- "$0")"
+CI_SCRIPT_DIR="$(cd "$(dirname -- "$0")" && pwd)"
+CI_TOPLEVEL_DIR="$(cd "$(dirname -- "${BASH_SOURCE[0]}")/../.." && pwd)"
+
+# Initialize the global constants CI_BUILD_{...} for the host build platform.
+CI_BUILD_ARCH="${CI_BUILD_ARCH:-"$(uname -m | tr 'A-Z/\.-' 'a-z____')"}"
+CI_BUILD_SYSTEM="${CI_BUILD_SYSTEM:-"$(uname -s | tr 'A-Z/\.-' 'a-z____')"}"
+
+# Initialize the global constants CI_TARGET_{...} for the target platform.
+CI_TARGET_ARCH="${CI_TARGET_ARCH:-"$CI_BUILD_ARCH"}"
+CI_TARGET_SYSTEM="${CI_TARGET_SYSTEM:-"$CI_BUILD_SYSTEM"}"
+
+function ci_info {
+    printf >&2 "%s: %s\\n" "$CI_SCRIPT_NAME" "$*"
+}
+
+function ci_warn {
+    printf >&2 "%s: warning: %s\\n" "$CI_SCRIPT_NAME" "$*"
+}
+
+function ci_err {
+    printf >&2 "%s: error: %s\\n" "$CI_SCRIPT_NAME" "$*"
+    exit 2
+}
+
+function ci_err_internal {
+    printf >&2 "%s: internal error: %s\\n" "$CI_SCRIPT_NAME" "$*"
+    printf >&2 "ABORTED\\n"
+    # Exit with the conventional SIGABRT code.
+    exit 134
+}
+
+function ci_expr {
+    if [[ ${*:-0} == [0-9] ]]
+    then
+        # This is the same as in the else-branch below, albeit much faster
+        # for our intended use cases.
+        return $((!$1))
+    else
+        # The funny-looking compound command "... && return $? || return $?"
+        # allows the execution to continue uninterrupted under "set -e".
+        expr >/dev/null "$@" && return $? || return $?
+    fi
+}
+
+function ci_spawn {
+    printf >&2 "%s: executing:" "$CI_SCRIPT_NAME"
+    printf >&2 " %q" "$@"
+    printf >&2 "\\n"
+    "$@"
+}
+
+# Ensure that the internal initialization is correct.
+[[ $CI_TOPLEVEL_DIR/ci/lib/ci.lib.sh -ef ${BASH_SOURCE[0]} ]] || {
+    ci_err_internal "bad or missing \$CI_TOPLEVEL_DIR"
+}
+[[ $CI_SCRIPT_DIR/$CI_SCRIPT_NAME -ef $0 ]] || {
+    ci_err_internal "bad or missing \$CI_SCRIPT_DIR/\$CI_SCRIPT_NAME"
+}
+[[ $CI_BUILD_ARCH && $CI_BUILD_SYSTEM ]] || {
+    ci_err_internal "missing \$CI_BUILD_ARCH or \$CI_BUILD_SYSTEM"
+}
+[[ $CI_TARGET_ARCH && $CI_TARGET_SYSTEM ]] || {
+    ci_err_internal "missing \$CI_TARGET_ARCH or \$CI_TARGET_SYSTEM"
+}
+
+# Ensure that the user initialization is correct.
+[[ ${CI_FORCE:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_FORCE: '$CI_FORCE'"
+}
+[[ ${CI_NO_BUILD:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_BUILD: '$CI_NO_BUILD'"
+}
+[[ ${CI_NO_TEST:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_TEST: '$CI_NO_TEST'"
+}
+[[ ${CI_NO_INSTALL:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+}
+[[ ${CI_NO_CLEAN:-0} == [01] ]] || {
+    ci_err "bad boolean option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"
+}
+if ci_expr $((CI_NO_BUILD))
+then
+    ci_expr $((CI_NO_TEST && CI_NO_INSTALL)) || {
+        ci_err "\$CI_NO_BUILD requires \$CI_NO_TEST and \$CI_NO_INSTALL"
+    }
+fi

ci/libexec/ci_shellify_autoconf.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_autoconf {
+    # Convert autoconf (M4) text, specifically originating
+    # from configure.ac, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNGLIB_*.
+    sed -n -e '/^ *PNGLIB_[^ ]*=[$"0-9A-Za-z_]/ p' |
+        sed -e 's/^ *PNG\([0-9A-Za-z_]*\)=\([^# ]*\).*$/PNG\1=\2/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] configure.ac"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == configure.ac ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'configure.ac')"
+    }
+    ci_shellify_autoconf <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_c.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_c {
+    # Convert C preprocessor text, specifically originating
+    # from png.h, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNG_LIBPNG_*.
+    sed -n -e '/^\# *define * PNG_LIBPNG_[^ ]* * ["0-9A-Za-z_]/ p' |
+        sed -e 's/^\# *define * PNG\([^ ]*\) * \([^ ]*\)/PNG\1=\2/' \
+            -e 's/=PNG\([0-9A-Za-z_]*\)/=\${PNG\1}/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] png.h"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == png.h ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'png.h')"
+    }
+    ci_shellify_c <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_cmake.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_cmake {
+    # Convert CMake lists text, specifically originating
+    # from CMakeLists.txt, to shell scripting text.
+    # Select only the easy-to-parse definitions of PNGLIB_*.
+    sed -n -e '/^ *set *(PNGLIB_[^ ]* * [$"0-9A-Za-z_].*)/ p' |
+        sed -e 's/^ *set *(PNG\([^ ]*\) * \([^() ]*\)).*$/PNG\1=\2/' \
+            -e 's/^\([^ ]*=[^ ]*\).*$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] CMakeLists.txt"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    filename="$(basename -- "$1")"
+    [[ $filename == [Cc][Mm]ake[Ll]ists.txt ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'CMakeLists.txt')"
+    }
+    ci_shellify_cmake <"$1"
+}
+
+main "$@"

ci/libexec/ci_shellify_shell.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+set -o errexit -o pipefail -o posix
+
+# Copyright (c) 2019-2025 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+# shellcheck source=ci/lib/ci.lib.sh
+source "$(dirname "$0")/../lib/ci.lib.sh"
+
+function ci_shellify_shell {
+    # Convert shell scripting text to shell scripting text.
+    # Select only the easy-to-parse version definitions.
+    sed -n -e '/^ *[A-Za-z_][0-9A-Za-z_]*=[0-9][^ #]* *$/ p' |
+        sed -e 's/^ *\([^ ]*=[^ ]*\) *$/export \1;/'
+}
+
+function usage {
+    echo "usage: $CI_SCRIPT_NAME [<options>] libpng-config-head.in"
+    echo "options: -?|-h|--help"
+    exit "${@:-0}"
+}
+
+function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help || $1 == --help=* ]] && usage 0
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    [[ $# -eq 0 ]] && usage 2
+    [[ $# -eq 1 ]] || ci_err "too many operands"
+    # And... go!
+    test -e "$1" || ci_err "no such file: '$1'"
+    [[ $(basename -- "$1") == libpng-config-head.in ]] || {
+        ci_err "incorrect operand: '$1' (expecting: 'libpng-config-head.in')"
+    }
+    ci_shellify_shell <"$1"
+}
+
+main "$@"

ci/targets/android/ci_env.aarch64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_ARCHVER=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.armv7a-linux-androideabi.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_ARCHVER=armv7a
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=androideabi
+export CI_TARGET_ABIVER=androideabi29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.i686-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_ARCHVER=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.x86_64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_ARCHVER=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/cygwin/ci_env.i686-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/cygwin/ci_env.x86_64-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.arm64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.x86_64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.aarch64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.i686-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.riscv64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.x86_64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.aarch64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabi.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabi
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabihf.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabihf
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.i686-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsel-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsel
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6el-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64le-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64le
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.riscv64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.x86_64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i386-pc-msdoswatcom.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i386
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl386"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+"

ci/targets/msdos/ci_env.i586-pc-msdosdjgpp.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i586
+export CI_TARGET_SYSTEM=msdosdjgpp
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Generic
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i86-pc-msdoswatcom.sh

@@ -0,0 +1,19 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i86
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+    -DCMAKE_SYSTEM_PROCESSOR=I86
+"

ci/targets/windows/ci_env.aarch64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=mingw32
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=mingw64
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

compile

@@ -1,9 +1,9 @@
 #! /bin/sh
 # Wrapper for compilers which do not understand '-c -o'.
 
-scriptversion=2018-03-07.03; # UTC
+scriptversion=2025-06-18.21; # UTC
 
-# Copyright (C) 1999-2018 Free Software Foundation, Inc.
+# Copyright (C) 1999-2025 Free Software Foundation, Inc.
 # Written by Tom Tromey <tromey@cygnus.com>.
 #
 # This program is free software; you can redistribute it and/or modify
@@ -37,11 +37,11 @@ IFS=" ""	$nl"
 
 file_conv=
 
-# func_file_conv build_file lazy
+# func_file_conv build_file unneeded_conversions
 # Convert a $build file to $host form and store it in $file
 # Currently only supports Windows hosts. If the determined conversion
-# type is listed in (the comma separated) LAZY, no conversion will
+# type is listed in (the comma separated) UNNEEDED_CONVERSIONS, no
-# take place.
+# conversion will take place.
 func_file_conv ()
 {
   file=$1
@@ -51,9 +51,20 @@ func_file_conv ()
 	# lazily determine how to convert abs files
 	case `uname -s` in
 	  MINGW*)
-	    file_conv=mingw
+	    if test -n "$MSYSTEM" && (cygpath --version) >/dev/null 2>&1; then
+	      # MSYS2 environment.
+	      file_conv=cygwin
+	    else
+	      # Original MinGW environment.
+	      file_conv=mingw
+	    fi
+	    ;;
+	  MSYS*)
+	    # Old MSYS environment, or MSYS2 with 32-bit MSYS2 shell.
+	    file_conv=cygwin
 	    ;;
 	  CYGWIN*)
+	    # Cygwin environment.
 	    file_conv=cygwin
 	    ;;
 	  *)
@@ -63,12 +74,14 @@ func_file_conv ()
       fi
       case $file_conv/,$2, in
 	*,$file_conv,*)
+	  # This is the optimization mentioned above:
+	  # If UNNEEDED_CONVERSIONS contains $file_conv, don't convert.
 	  ;;
 	mingw/*)
 	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
 	  ;;
 	cygwin/*)
-	  file=`cygpath -m "$file" || echo "$file"`
+	  file=`cygpath -w "$file" || echo "$file"`
 	  ;;
 	wine/*)
 	  file=`winepath -w "$file" || echo "$file"`
@@ -143,7 +156,7 @@ func_cl_wrapper ()
 	  # configure might choose to run compile as 'compile cc -o foo foo.c'.
 	  eat=1
 	  case $2 in
-	    *.o | *.[oO][bB][jJ])
+	    *.o | *.lo | *.[oO][bB][jJ])
 	      func_file_conv "$2"
 	      set x "$@" -Fo"$file"
 	      shift
@@ -248,14 +261,17 @@ If you are trying to build a whole package this is not the
 right script to run: please start by reading the file 'INSTALL'.
 
 Report bugs to <bug-automake@gnu.org>.
+GNU Automake home page: <https://www.gnu.org/software/automake/>.
+General help using GNU software: <https://www.gnu.org/gethelp/>.
 EOF
     exit $?
     ;;
   -v | --v*)
-    echo "compile $scriptversion"
+    echo "compile (GNU Automake) $scriptversion"
     exit $?
     ;;
   cl | *[/\\]cl | cl.exe | *[/\\]cl.exe | \
+  clang-cl | *[/\\]clang-cl | clang-cl.exe | *[/\\]clang-cl.exe | \
   icl | *[/\\]icl | icl.exe | *[/\\]icl.exe )
     func_cl_wrapper "$@"      # Doesn't return...
     ;;
@@ -340,9 +356,9 @@ exit $ret
 # Local Variables:
 # mode: shell-script
 # sh-indentation: 2
-# eval: (add-hook 'before-save-hook 'time-stamp)
+# eval: (add-hook 'before-save-hook 'time-stamp nil t)
 # time-stamp-start: "scriptversion="
-# time-stamp-format: "%:y-%02m-%02d.%02H"
+# time-stamp-format: "%Y-%02m-%02d.%02H"
 # time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:

config.h.in

@@ -3,30 +3,27 @@
 /* Define to 1 if you have the <dlfcn.h> header file. */
 #undef HAVE_DLFCN_H
 
-/* Define to 1 if you have the `feenableexcept' function. */
+/* Define to 1 if you have the 'feenableexcept' function. */
 #undef HAVE_FEENABLEEXCEPT
 
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
-/* Define to 1 if you have the `m' library (-lm). */
+/* Define to 1 if you have the 'm' library (-lm). */
 #undef HAVE_LIBM
 
-/* Define to 1 if you have the `z' library (-lz). */
+/* Define to 1 if you have the 'z' library (-lz). */
 #undef HAVE_LIBZ
 
-/* Define to 1 if you have the <memory.h> header file. */
+/* Define to 1 if you have the 'pow' function. */
-#undef HAVE_MEMORY_H
-
-/* Define to 1 if you have the `memset' function. */
-#undef HAVE_MEMSET
-
-/* Define to 1 if you have the `pow' function. */
 #undef HAVE_POW
 
 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H
 
+/* Define to 1 if you have the <stdio.h> header file. */
+#undef HAVE_STDIO_H
+
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
@@ -81,6 +78,18 @@
 /* Enable Intel SSE optimizations */
 #undef PNG_INTEL_SSE_OPT
 
+/* Enable LOONGARCH LSX optimizations */
+#undef PNG_LOONGARCH_LSX_OPT
+
+/* Turn on MIPS MMI optimizations at run-time */
+#undef PNG_MIPS_MMI_API_SUPPORTED
+
+/* Check for MIPS MMI support at run-time */
+#undef PNG_MIPS_MMI_CHECK_SUPPORTED
+
+/* Enable MIPS MMI optimizations */
+#undef PNG_MIPS_MMI_OPT
+
 /* Turn on MIPS MSA optimizations at run-time */
 #undef PNG_MIPS_MSA_API_SUPPORTED
 
@@ -99,31 +108,31 @@
 /* Enable POWERPC VSX optimizations */
 #undef PNG_POWERPC_VSX_OPT
 
-/* Define to 1 if you have the ANSI C header files. */
+/* Enable RISCV RVV optimizations */
+#undef PNG_RISCV_RVV_OPT
+
+/* Define to 1 if all of the C89 standard headers exist (not just the ones
+   required in a freestanding environment). This macro is provided for
+   backward compatibility; new code need not use it. */
 #undef STDC_HEADERS
 
-/* Define to 1 if your <sys/time.h> declares `struct tm'. */
+/* Define to 1 if your <sys/time.h> declares 'struct tm'. */
 #undef TM_IN_SYS_TIME
 
 /* Version number of package */
 #undef VERSION
 
-/* Define to empty if `const' does not conform to ANSI C. */
-#undef const
-
 /* Define to the equivalent of the C99 'restrict' keyword, or to
    nothing if this is not supported.  Do not define if restrict is
-   supported directly.  */
+   supported only directly.  */
 #undef restrict
-/* Work around a bug in Sun C++: it does not support _Restrict or
+/* Work around a bug in older versions of Sun C++, which did not
-   __restrict__, even though the corresponding Sun C compiler ends up with
+   #define __restrict__ or support _Restrict or __restrict__
-   "#define restrict _Restrict" or "#define restrict __restrict__" in the
+   even though the corresponding Sun C compiler ended up with
-   previous line.  Perhaps some future version of Sun C++ will work with
+   "#define restrict _Restrict" or "#define restrict __restrict__"
-   restrict; if so, hopefully it defines __RESTRICT like Sun C does.  */
+   in the previous line.  This workaround can be removed once
-#if defined __SUNPRO_CC && !defined __RESTRICT
+   we assume Oracle Developer Studio 12.5 (2016) or later.  */
+#if defined __SUNPRO_CC && !defined __RESTRICT && !defined __restrict__
 # define _Restrict
 # define __restrict__
 #endif
-
-/* Define to `unsigned int' if <sys/types.h> does not define. */
-#undef size_t

configure.ac

@@ -1,7 +1,7 @@
 # configure.ac
 
+# Copyright (c) 2018-2024 Cosmin Truta
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
 
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
@@ -25,8 +25,8 @@ AC_PREREQ([2.68])
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.35],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.51.git],[png-mng-implement@lists.sourceforge.net])
-AC_CONFIG_MACRO_DIR([scripts])
+AC_CONFIG_MACRO_DIR([scripts/autoconf])
 
 # libpng does not follow GNU file name conventions (hence 'foreign')
 # color-tests requires automake 1.11 or later
@@ -46,17 +46,17 @@ 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=1.6.35
+PNGLIB_VERSION=1.6.51.git
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=35
+PNGLIB_RELEASE=51
 
 dnl End of version number stuff
 
 AC_CONFIG_SRCDIR([pngget.c])
 AC_CONFIG_HEADERS([config.h])
 
-# Checks for programs.
+# Check the basic programs.
 AC_LANG([C])
 AC_PROG_CC
 AM_PROG_AS
@@ -72,16 +72,19 @@ dnl compatible later version may be used
 LT_INIT([win32-dll])
 LT_PREREQ([2.4.2])
 
-# Some awks crash when confronted with pnglibconf.dfa, do a test run now
+dnl Declare the AWK variable.
-# to make sure this doesn't happen
+AC_ARG_VAR(AWK, [AWK language processor])
-AC_MSG_CHECKING([that AWK works])
+
+# Some awk implementations crash when confronted with pnglibconf.dfa.
+# Run a test now, to make sure this doesn't happen.
+AC_MSG_CHECKING([if awk ($AWK) works])
 if ${AWK} -f ${srcdir}/scripts/options.awk out="/dev/null" version=search\
    ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
    ${srcdir}/pngusr.dfa 1>&2
 then
-   AC_MSG_RESULT([ok])
+   AC_MSG_RESULT([yes])
 else
-   AC_MSG_FAILURE([failed], 1)
+   AC_MSG_FAILURE([no], 1)
 fi
 
 # This is a remnant of the old cc -E validation, where it may have been
@@ -89,11 +92,29 @@ fi
 DFNCPP="$CPP"
 AC_SUBST(DFNCPP)
 
-# -Werror cannot be passed to GCC in CFLAGS because configure will fail (it
+AC_ARG_ENABLE([tests],
-# checks the compiler with a program that generates a warning), add the
+   AS_HELP_STRING([--disable-tests],
-# following option to deal with this
+      [do not build the test programs (default is to build)]),
+      [enable_tests="$enableval"],
+      [enable_tests=yes])
+
+AM_CONDITIONAL([ENABLE_TESTS],
+   [test "$enable_tests" != "no"])
+
+AC_ARG_ENABLE([tools],
+   AS_HELP_STRING([--disable-tools],
+      [do not build the auxiliary tools (default is to build)]),
+      [enable_tools="$enableval"],
+      [enable_tools=yes])
+
+AM_CONDITIONAL([ENABLE_TOOLS],
+   [test "$enable_tools" != "no"])
+
+# -Werror cannot be passed to GCC in CFLAGS because configure will fail
+# (it checks the compiler with a program that generates a warning).
+# Add the following option to deal with this:
 AC_ARG_VAR(PNG_COPTS,
-   [additional flags for the C compiler, use this for options that would]
+   [additional flags for the C compiler, to be used for options that would]
    [cause configure itself to fail])
 AC_ARG_ENABLE(werror,
    AS_HELP_STRING([[[--enable-werror[=OPT]]]],
@@ -114,10 +135,10 @@ AC_ARG_ENABLE(werror,
       CFLAGS="$sav_CFLAGS"
     fi],)
 
-# For GCC 5 the default mode for C is -std=gnu11 instead of -std=gnu89
+# For GCC 5 the default mode for C is -std=gnu11 instead of -std=gnu89.
-# In pngpriv.h we request just the POSIX 1003.1 and C89 APIs by defining _POSIX_SOURCE to 1
+# In pngpriv.h we request just the POSIX 1003.1 and C89 APIs by defining
-# This is incompatible with the new default mode, so we test for that and force the 
+# _POSIX_SOURCE to 1. This is incompatible with the new default mode, so
-# "-std=c89" compiler option:
+# we test for that and force the "-std=c89" compiler option:
 AC_MSG_CHECKING([if we need to force back C standard to C89])
 AC_COMPILE_IFELSE(
    [AC_LANG_PROGRAM([
@@ -133,23 +154,17 @@ AC_COMPILE_IFELSE(
    CFLAGS="$CFLAGS -std=c89"
 ])
 
-# Checks for header files.
+# Checks for structures and compiler characteristics.
-AC_HEADER_STDC
-
-# Checks for typedefs, structures, and compiler characteristics.
-AC_C_CONST
-AC_TYPE_SIZE_T
 AC_STRUCT_TM
 AC_C_RESTRICT
 
 # Checks for library functions.
-AC_FUNC_STRTOD
+AC_CHECK_FUNCS([pow], ,
-AC_CHECK_FUNCS([memset], , AC_MSG_ERROR(memset not found in libc))
+  [AC_CHECK_LIB([m], [pow], , [AC_MSG_ERROR([cannot find pow])])])
-AC_CHECK_FUNCS([pow], , AC_CHECK_LIB(m, pow, , AC_MSG_ERROR(cannot find pow)) )
 
-# Some later POSIX 1003.1 functions are required for test programs, failure here
+# Some later POSIX 1003.1 functions are required for test programs, failure
-# is soft (the corresponding test program is not built).
+# here is soft (the corresponding test program is not built).
-AC_CHECK_FUNC([clock_gettime],,[AC_MSG_WARN([not building timepng])])
+AC_CHECK_FUNC([clock_gettime], , [AC_MSG_WARN([not building timepng])])
 AM_CONDITIONAL([HAVE_CLOCK_GETTIME], [test "$ac_cv_func_clock_gettime" = "yes"])
 
 AC_ARG_WITH(zlib-prefix,
@@ -157,8 +172,9 @@ AC_ARG_WITH(zlib-prefix,
       [prefix that may have been used in installed zlib]),
       [ZPREFIX=${withval}],
       [ZPREFIX='z_'])
-AC_CHECK_LIB(z, zlibVersion, ,
+AC_CHECK_LIB([z], [zlibVersion], ,
-    AC_CHECK_LIB(z, ${ZPREFIX}zlibVersion, , AC_MSG_ERROR(zlib not installed)))
+  [AC_CHECK_LIB([z], [${ZPREFIX}zlibVersion], ,
+     [AC_MSG_ERROR([zlib not installed])])])
 
 # The following is for pngvalid, to ensure it catches FP errors even on
 # platforms that don't enable FP exceptions, the function appears in the math
@@ -210,9 +226,9 @@ AM_CONDITIONAL(HAVE_LD_VERSION_SCRIPT, test "$have_ld_version_script" = "yes")
 if test "$have_ld_version_script" = "yes"; then
     AC_MSG_CHECKING([for symbol prefix])
     SYMBOL_PREFIX=`echo "PREFIX=__USER_LABEL_PREFIX__" \
-                  | ${CPP-${CC-gcc} -E} - 2>&1 \
+                  | ${CPP:-${CC:-gcc} -E} - 2>&1 \
-                  | ${EGREP-grep} "^PREFIX=" \
+                  | ${EGREP:-grep} "^PREFIX=" \
-                  | ${SED-sed} -e "s:^PREFIX=::" -e "s:__USER_LABEL_PREFIX__::"`
+                  | ${SED:-sed} -e "s:^PREFIX=::" -e "s:__USER_LABEL_PREFIX__::"`
     AC_SUBST(SYMBOL_PREFIX)
     AC_MSG_RESULT($SYMBOL_PREFIX)
 fi
@@ -297,7 +313,7 @@ AC_ARG_ENABLE([unversioned-libpng-config],
 AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
    [test "$enable_unversioned_libpng_config" != "no"])
 
-# HOST SPECIFIC OPTIONS
+# HOST-SPECIFIC OPTIONS
 # =====================
 #
 # DEFAULT
@@ -305,7 +321,7 @@ AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
 #
 AC_ARG_ENABLE([hardware-optimizations],
    AS_HELP_STRING([[[--enable-hardware-optimizations]]],
-      [Enable hardware optimizations: =no/off, yes/on:]),
+      [Enable hardware optimizations: =no/off, yes/on.]),
    [case "$enableval" in
       no|off)
          # disable hardware optimization on all systems:
@@ -315,24 +331,36 @@ AC_ARG_ENABLE([hardware-optimizations],
          enable_mips_msa=no
          AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
            [Disable MIPS_MSA optimizations])
+         enable_mips_mmi=no
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [0],
+           [Disable MIPS_MMI optimizations])
          enable_powerpc_vsx=no
          AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
            [Disable POWERPC VSX optimizations])
          enable_intel_sse=no
          AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
            [Disable INTEL_SSE optimizations])
+         enable_loongarch_lsx=no
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [0],
+           [Disable LOONGARCH_LSX optimizations])
+         enable_riscv_rvv=no
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [0],
+           [Disable RISC-V Vector optimizations])
          ;;
       *)
          # allow enabling hardware optimization on any system:
          case "$host_cpu" in
             arm*|aarch64*)
               enable_arm_neon=yes
-              AC_DEFINE([PNG_ARM_NEON_OPT], [0],
+              AC_DEFINE([PNG_ARM_NEON_OPT], [2],
                 [Enable ARM_NEON optimizations])
               ;;
             mipsel*|mips64el*)
+              enable_mips_mmi=yes
               enable_mips_msa=yes
-              AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
+              AC_DEFINE([PNG_MIPS_MMI_OPT], [1],
+                [Enable MIPS_MMI optimizations])
+              AC_DEFINE([PNG_MIPS_MSA_OPT], [2],
                 [Enable MIPS_MSA optimizations])
               ;;
             i?86|x86_64)
@@ -345,21 +373,30 @@ AC_ARG_ENABLE([hardware-optimizations],
               AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
                 [Enable POWERPC VSX optimizations])
               ;;
+            loongarch*)
+              enable_loongarch_lsx=yes
+              AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                [Enable LOONGARCH_LSX optimizations])
+              ;;
+            riscv64)
+              enable_riscv_rvv=yes
+              AC_DEFINE([PNG_RISCV_RVV_OPT], [2],
+                [Enable RISC-V Vector optimizations])
+              ;;
          esac
          ;;
    esac])
 
-# ARM
+# ARM NEON
-# ===
+# ========
-#
-# ARM NEON (SIMD) support.
 
 AC_ARG_ENABLE([arm-neon],
    AS_HELP_STRING([[[--enable-arm-neon]]],
-      [Enable ARM NEON optimizations: =no/off, check, api, yes/on:]
+      [Enable ARM NEON optimizations: =no/off, check, api, yes/on.]
-      [no/off: disable the optimizations; check: use internal checking code]
+      [no/off: disable the optimizations;]
-      [(deprecated and poorly supported); api: disable by default, enable by]
+      [check: use internal checking code (deprecated and poorly supported);]
-      [a call to png_set_option; yes/on: turn on unconditionally.]
+      [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 "$enableval" in
       no|off)
@@ -367,7 +404,7 @@ AC_ARG_ENABLE([arm-neon],
          AC_DEFINE([PNG_ARM_NEON_OPT], [0],
                    [Disable ARM Neon optimizations])
          # Prevent inclusion of the assembler files below:
-         enable_arm_neon=no;;
+         enable_arm_neon=no ;;
       check)
          AC_DEFINE([PNG_ARM_NEON_CHECK_SUPPORTED], [],
                    [Check for ARM Neon support at run-time]);;
@@ -377,35 +414,35 @@ AC_ARG_ENABLE([arm-neon],
       yes|on)
          AC_DEFINE([PNG_ARM_NEON_OPT], [2],
                    [Enable ARM Neon optimizations])
-         AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api', if]
+         AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api';]
-            [you want the optimizations unconditionally pass -mfpu=neon]
+            [if you want the optimizations unconditionally,]
-            [to the compiler.]);;
+            [pass '-mfpu=neon' to the compiler.]);;
       *)
-         AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}: invalid value])
+         AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}:]
+                      [invalid argument])
    esac])
 
-# Add ARM specific files to all builds where the host_cpu is arm ('arm*') or
+# Add ARM-specific files to all builds where $host_cpu is arm ('arm*') or
-# where ARM optimizations were explicitly requested (this allows a fallback if a
+# where ARM optimizations were explicitly requested. (This allows a fallback
-# future host CPU does not match 'arm*')
+# if a future host CPU does not match 'arm*'.)
 
 AM_CONDITIONAL([PNG_ARM_NEON],
    [test "$enable_arm_neon" != 'no' &&
     case "$host_cpu" in
-      arm*|aarch64*) :;;
+      arm*|aarch64*) : ;;
-      *)    test "$enable_arm_neon" != '';;
+      *)    test "$enable_arm_neon" != '' ;;
     esac])
 
-# MIPS
+# MIPS MSA
-# ===
+# ========
-#
-# MIPS MSA (SIMD) support.
 
 AC_ARG_ENABLE([mips-msa],
    AS_HELP_STRING([[[--enable-mips-msa]]],
-      [Enable MIPS MSA optimizations: =no/off, check, api, yes/on:]
+      [Enable MIPS MSA optimizations: =no/off, check, api, yes/on.]
-      [no/off: disable the optimizations; check: use internal checking code]
+      [no/off: disable the optimizations;]
-      [(deprecated and poorly supported); api: disable by default, enable by]
+      [check: use internal checking code (deprecated and poorly supported);]
-      [a call to png_set_option; yes/on: turn on unconditionally.]
+      [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 "$enableval" in
       no|off)
@@ -413,7 +450,7 @@ AC_ARG_ENABLE([mips-msa],
          AC_DEFINE([PNG_MIPS_MSA_OPT], [0],
                    [Disable MIPS MSA optimizations])
          # Prevent inclusion of the assembler files below:
-         enable_mips_msa=no;;
+         enable_mips_msa=no ;;
       check)
          AC_DEFINE([PNG_MIPS_MSA_CHECK_SUPPORTED], [],
                    [Check for MIPS MSA support at run-time]);;
@@ -423,31 +460,75 @@ AC_ARG_ENABLE([mips-msa],
       yes|on)
          AC_DEFINE([PNG_MIPS_MSA_OPT], [2],
                    [Enable MIPS MSA optimizations])
-         AC_MSG_WARN([--enable-mips-msa: please specify 'check' or 'api', if]
+         AC_MSG_WARN([--enable-mips-msa: please specify 'check' or 'api';]
-            [you want the optimizations unconditionally pass '-mmsa -mfp64']
+            [if you want the optimizations unconditionally,]
-            [to the compiler.]);;
+            [pass '-mmsa -mfp64' to the compiler.]);;
       *)
-         AC_MSG_ERROR([--enable-mips-msa=${enable_mips_msa}: invalid value])
+         AC_MSG_ERROR([--enable-mips-msa=${enable_mips_msa}:]
+                      [invalid argument])
    esac])
 
-# Add MIPS specific files to all builds where the host_cpu is mips ('mips*') or
+# Add MIPS-specific files to all builds where $host_cpu is mips ('mips*') or
-# where MIPS optimizations were explicitly requested (this allows a fallback if a
+# where MIPS optimizations were explicitly requested. (This allows a fallback
-# future host CPU does not match 'mips*')
+# if a future host CPU does not match 'mips*'.)
 
 AM_CONDITIONAL([PNG_MIPS_MSA],
    [test "$enable_mips_msa" != 'no' &&
     case "$host_cpu" in
-      mipsel*|mips64el*) :;;
+      mipsel*|mips64el*) : ;;
     esac])
 
-# INTEL
+# MIPS MMI
-# =====
+# ========
-#
+
-# INTEL SSE (SIMD) support.
+AC_ARG_ENABLE([mips-mmi],
+   AS_HELP_STRING([[[--enable-mips-mmi]]],
+      [Enable MIPS MMI optimizations: =no/off, check, api, yes/on.]
+      [no/off: disable the optimizations;]
+      [check: use internal checking code (deprecated and poorly supported);]
+      [api: disable by default, enable by a call to png_set_option;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __mips_mmi systems:
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [0],
+                   [Disable MIPS MMI optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_mips_mmi=no;;
+      check)
+         AC_DEFINE([PNG_MIPS_MMI_CHECK_SUPPORTED], [],
+                   [Check for MIPS MMI support at run-time]);;
+      api)
+         AC_DEFINE([PNG_MIPS_MMI_API_SUPPORTED], [],
+                   [Turn on MIPS MMI optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_MIPS_MMI_OPT], [1],
+                   [Enable MIPS MMI optimizations])
+         AC_MSG_WARN([--enable-mips-mmi: please specify 'check' or 'api';]
+            [if you want the optimizations unconditionally]
+            [pass '-mloongson-mmi -march=loongson3a' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-mips-mmi=${enable_mips_mmi}:]
+                      [invalid argument])
+   esac])
+
+# Add MIPS specific files to all builds where the host_cpu is mips ('mips*') or
+# where MIPS optimizations were explicitly requested. (This allows a fallback
+# if a future host CPU does not match 'mips*'.)
+
+AM_CONDITIONAL([PNG_MIPS_MMI],
+   [test "$enable_mips_mmi" != 'no' &&
+    case "$host_cpu" in
+      mipsel*|mips64el*) : ;;
+    esac])
+
+# INTEL SSE
+# =========
 
 AC_ARG_ENABLE([intel-sse],
    AS_HELP_STRING([[[--enable-intel-sse]]],
-      [Enable Intel SSE optimizations: =no/off, yes/on:]
+      [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.]),
@@ -457,34 +538,34 @@ AC_ARG_ENABLE([intel-sse],
          AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
                    [Disable Intel SSE optimizations])
          # Prevent inclusion of the assembler files below:
-         enable_intel_sse=no;;
+         enable_intel_sse=no ;;
       yes|on)
          AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
                    [Enable Intel SSE optimizations]);;
       *)
-         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}:]
+                      [invalid argument])
    esac])
 
-# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
+# Add Intel-specific files to all builds where $host_cpu is Intel ('x86*') or
-# or where Intel optimizations were explicitly requested (this allows a
+# where Intel optimizations were explicitly requested. (This allows a fallback
-# fallback if a future host CPU does not match 'x86*')
+# if a future host CPU does not match 'x86*'.)
 AM_CONDITIONAL([PNG_INTEL_SSE],
    [test "$enable_intel_sse" != 'no' &&
     case "$host_cpu" in
-      i?86|x86_64) :;;
+      i?86|x86_64) : ;;
-      *)    test "$enable_intel_sse" != '';;
+      *)    test "$enable_intel_sse" != '' ;;
     esac])
 
-# PowerPC
+# POWERPC VSX
-# ===
+# ===========
-#
-# 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:]
+      [Enable POWERPC VSX optimizations: =no/off, check, api, yes/on.]
-      [no/off: disable the optimizations; check: use internal checking code]
+      [no/off: disable the optimizations;]
-      [api: disable by default, enable by a call to png_set_option]
+      [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 "$enableval" in
@@ -492,36 +573,171 @@ AS_HELP_STRING([[[--enable-powerpc-vsx]]],
          # disable the default enabling on __ppc64__ systems:
          AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
                    [Disable POWERPC VSX optimizations])
-         # Prevent inclusion of the platform specific files below:
+         # Prevent inclusion of the platform-specific files below:
-         enable_powerpc_vsx=no;;
+         enable_powerpc_vsx=no ;;
       check)
          AC_DEFINE([PNG_POWERPC_VSX_CHECK_SUPPORTED], [],
                    [Check for POWERPC VSX support at run-time])
-         AC_MSG_WARN([--enable-powerpc-vsx Please check contrib/powerpc/README file]
+         AC_MSG_WARN([--enable-powerpc-vsx: please see contrib/powerpc/README]
-            [for the list of supported OSes.]);;
+                     [for the list of supported systems.]);;
       api)
          AC_DEFINE([PNG_POWERPC_VSX_API_SUPPORTED], [],
                    [Turn on POWERPC VSX optimizations at run-time]);;
       yes|on)
          AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
                    [Enable POWERPC VSX optimizations])
-         AC_MSG_WARN([--enable-powerpc-vsx: please specify 'check' or 'api', if]
+         AC_MSG_WARN([--enable-powerpc-vsx: please specify 'check' or 'api';]
-            [you want the optimizations unconditionally pass '-maltivec -mvsx']
+            [if you want the optimizations unconditionally,]
-            [or '-mcpu=power8'to the compiler.]);;
+            [pass '-maltivec -mvsx' or '-mcpu=power8' to the compiler.]);;
       *)
-         AC_MSG_ERROR([--enable-powerpc-vsx=${enable_powerpc_vsx}: invalid value])
+         AC_MSG_ERROR([--enable-powerpc-vsx=${enable_powerpc_vsx}:]
+                      [invalid argument])
    esac])
 
-# Add PowerPC specific files to all builds where the host_cpu is powerpc('powerpc*') or
+# Add PowerPC-specific files to all builds where $host_cpu is powerpc
-# where POWERPC optimizations were explicitly requested (this allows a fallback if a
+# ('powerpc*') or where PowerPC optimizations were explicitly requested.
-# future host CPU does not match 'powerpc*')
+# (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*) :;;
+      powerpc*|ppc64*) : ;;
     esac])
 
+# LOONGARCH LSX
+# =============
+
+AC_ARG_ENABLE([loongarch-lsx],
+   AS_HELP_STRING([[[--enable-loongarch-lsx]]],
+      [Enable LOONGARCH LSX optimizations: =no/off, yes/on:]
+      [no/off: disable the optimizations;]
+      [yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __loongarch_simd systems:
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [0],
+                   [Disable LOONGARCH LSX optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_loongarch_lsx=no;;
+      yes|on)
+         AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                   [Enable LOONGARCH LSX optimizations])
+         ;;
+      *)
+         AC_MSG_ERROR([--enable-loongarch-lsx=${enable_loongarch_lsx}:]
+                      [invalid argument])
+   esac])
+
+if test "$enable_loongarch_lsx" != "no" &&
+   case "$host_cpu" in
+      loongarch*) : ;;
+      *)    test "$enable_loongarch_lsx" != '' ;;
+   esac
+then
+   compiler_support_loongarch_lsx=no
+   AC_MSG_CHECKING(whether to use LoongArch LSX intrinsics)
+   save_CFLAGS="$CFLAGS"
+   LSX_CFLAGS="${LSX_CFLAGS:-"-mlsx"}"
+   CFLAGS="$CFLAGS $LSX_CFLAGS"
+   AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <lsxintrin.h>
+int main(){
+   __m128i a, b, c;
+   a = __lsx_vadd_w(b, c);
+   return 0;
+}]])],compiler_support_loongarch_lsx=yes)
+   CFLAGS="$save_CFLAGS"
+   AC_MSG_RESULT($compiler_support_loongarch_lsx)
+   if test "$compiler_support_loongarch_lsx" = "yes"; then
+      AC_DEFINE([PNG_LOONGARCH_LSX_OPT], [1],
+                [Enable LOONGARCH LSX optimizations])
+   else
+      AC_MSG_WARN([Compiler does not support loongarch LSX.])
+   fi
+fi
+
+# Add LoongArch specific files to all builds where the host_cpu is loongarch
+# ('loongarch*') or where LoongArch optimizations were explicitly requested.
+# (This allows a fallback if a future host CPU does not match 'loongarch*'.)
+
+AM_CONDITIONAL([PNG_LOONGARCH_LSX],
+   [test "$enable_loongarch_lsx" != "no" &&
+    test "$compiler_support_loongarch_lsx" = "yes" &&
+    case "$host_cpu" in
+      loongarch*) : ;;
+      *)    test "$enable_loongarch_lsx" != '' ;;
+    esac])
+
+# RISC-V
+# ======
+#
+# RISC-V Vector support.
+
+AC_ARG_ENABLE([riscv-rvv],
+AS_HELP_STRING([[[--enable-riscv-rvv]]],
+      [Enable RISC-V Vector 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. If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __riscv systems:
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [0],
+                   [Disable RISC-V Vector optimizations])
+         # Prevent inclusion of the platform-specific files below:
+         enable_riscv_rvv=no ;;
+      yes|on)
+         AC_DEFINE([PNG_RISCV_RVV_OPT], [2],
+                   [Enable RISC-V Vector optimizations])
+         AC_MSG_WARN([--enable-riscv-rvv:]
+            [if you want the optimizations pass e.g. '-march=rv64gv1p0' to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-riscv-rvv=${enable_riscv_rvv}: invalid value])
+   esac])
+
+if test "$enable_riscv_rvv" != "no" &&
+   case "$host_cpu" in
+      riscv64) : ;;
+      *)    test "$enable_riscv_rvv" != '' ;;
+   esac
+then
+   compiler_support_riscv_rvv=no
+   AC_MSG_CHECKING(whether to use RISC-V RVV intrinsics)
+
+   AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <riscv_vector.h>
+#include <asm/hwcap.h>
+#ifndef COMPAT_HWCAP_ISA_V /* added in linux-6.5 */
+#error "COMPAT_HWCAP_ISA_V is not available"
+#endif
+int main() {
+   const float src[] = { 0.0f, 0.0f, 0.0f, 0.0f };
+   uint64_t ptr[2] = {0x0908060504020100, 0xFFFFFFFF0E0D0C0A};
+   vuint8m1_t a = __riscv_vreinterpret_v_u64m1_u8m1(__riscv_vle64_v_u64m1(ptr, 2));
+   vfloat32m1_t val = __riscv_vle32_v_f32m1((const float*)(src), 4);
+   return (int)__riscv_vfmv_f_s_f32m1_f32(val);
+}]])],compiler_support_riscv_rvv=yes)
+   AC_MSG_RESULT($compiler_support_riscv_rvv)
+   if test "$compiler_support_riscv_rvv" = "yes"; then
+      AC_DEFINE([PNG_RISCV_RVV_OPT], [1],
+                [Enable RISCV RVV optimizations])
+   else
+      AC_MSG_WARN([Compiler does not support riscv rvv.])
+   fi
+fi
+
+# Add RISC-V-specific files to all builds where $host_cpu is riscv ('riscv64')
+# or where RISC-V optimizations were explicitly requested (this allows a fallback
+# if a future host CPU does not match 'riscv64')
+
+AM_CONDITIONAL([PNG_RISCV_RVV],
+   [test "$enable_riscv_rvv" != "no" &&
+    test "$compiler_support_riscv_rvv" = "yes" &&
+    case "$host_cpu" in
+      riscv64) : ;;
+      *)    test "$compiler_support_riscv_rvv" != '' ;;
+    esac])
 
 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
 

contrib/.editorconfig

@@ -0,0 +1,9 @@
+# https://editorconfig.org
+
+root = false
+
+[*.[ch]]
+indent_size = unset
+indent_style = unset
+max_doc_length = unset
+max_line_length = unset

contrib/README.txt

@@ -1,3 +1,5 @@
+External contributions to libpng
+--------------------------------
 
 This "contrib" directory contains contributions which are not necessarily under
 the libpng license, although all are open source.  They are not part of

contrib/arm-neon/android-ndk.c

@@ -2,7 +2,6 @@
  *
  * Copyright (c) 2014 Glenn Randers-Pehrson
  * Written by John Bowler, 2014.
- * Last changed in libpng 1.6.10 [March 6, 2014]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -24,6 +23,7 @@
  * has been compiled only, not linked: no version of the library has been found,
  * only the header files exist in the NDK.
  */
+
 #include <cpu-features.h>
 
 static int

contrib/arm-neon/linux-auxv.c

@@ -2,7 +2,6 @@
  *
  * Copyright (c) 2014 Glenn Randers-Pehrson
  * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.10 [March 6, 2014]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -22,6 +21,7 @@
  * This generic __linux__ implementation requires reading /proc/self/auxv and
  * looking at each element for one that records NEON capabilities.
  */
+
 #include <unistd.h> /* for POSIX 1003.1 */
 #include <errno.h>  /* for EINTR */
 

contrib/arm-neon/linux.c

@@ -1,6 +1,5 @@
 /* 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.
  *
@@ -19,6 +18,7 @@
  * 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>
 
 static int

contrib/conftest/basic.dfa

@@ -0,0 +1,133 @@
+# basic.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2024
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with basic read and write support.  This enables the lowest
+# level libpng read and write APIs - the "row-by-row" ones.
+#
+# Support is enabled only for those transformations that are observed to be
+# required by widely used apps or are in the v3 specification.
+#
+
+everything = off
+
+# The sequential read code is enabled here; the progressive code can be used
+# instead but there is no point enabling both.
+
+option READ on
+option SEQUENTIAL_READ on
+option EASY_ACCESS on
+option SET_USER_LIMITS on
+option INFO_IMAGE on
+option READ_16BIT on
+
+# Errors: these can be disabled but then there won't be any error messages
+# just failures and the error messages are really needed for apps:
+option WARNINGS on
+option ERROR_TEXT on
+option BENIGN_READ_ERRORS on
+
+# Required for many display programs such as web browsers:
+option PROGRESSIVE_READ on
+
+# Switch on the write code - this makes a minimalist encoder but with
+# interlace support turned on; otherwise png_read_png..png_write_png will
+# fail on an interlaced image.
+option WRITE on
+option WRITE_INTERLACING on
+option WRITE_16BIT on
+
+# Usages of the 'fixed' APIs are relatively rare but they do occur
+# one or the other for both the API and the internal math.
+
+#Fixed point:
+option FIXED_POINT on
+
+#Floating point:
+option FLOATING_POINT on
+option FLOATING_ARITHMETIC on
+
+# Basic error handling, IO and user memory support.  The latter allows the
+# application program to provide its own implementations of 'malloc' and 'free'.
+option SETJMP on
+option STDIO on
+option USER_MEM on
+
+# Gamma handling: this needs to be on for the gamma handling
+option READ_GAMMA on
+
+# The supported chunks
+chunk bKGD on
+chunk cHRM on
+chunk eXIf on
+chunk gAMA on
+chunk iCCP on
+chunk iTXt on
+chunk pHYs on
+chunk sBIT on
+chunk sRGB on
+chunk tEXt on
+chunk tIME on
+chunk tRNS on
+chunk zTXt on
+
+# These don't seem to be used anywhere:
+# chunk pCAL
+# chunk sCAL
+# chunk sPLT
+
+# The rest of this is app dependent: none of these options are required for
+# read/write of the full range of PNG files and the normal chunk handling on
+# read.
+option WRITE_CUSTOMIZE_ZTXT_COMPRESSION on
+option WRITE_CUSTOMIZE_COMPRESSION on
+
+option READ_EXPAND on
+option READ_FILLER on
+option READ_GRAY_TO_RGB on
+option READ_INVERT on
+option READ_PACK on
+option READ_RGB_TO_GRAY on
+option READ_SCALE_16_TO_8 on
+option READ_SHIFT on
+option READ_STRIP_16_TO_8 on
+option READ_STRIP_ALPHA on
+option READ_SWAP on
+
+option CONVERT_tIME on
+
+# optipng
+option IO_STATE on
+option STORE_UNKNOWN_CHUNKS on
+option HANDLE_AS_UNKNOWN on
+
+# pngcrush
+option READ_USER_TRANSFORM on
+option WRITE_FLUSH on
+
+# pnmtopng
+chunk hIST on
+
+# cairo
+option WRITE_PACKSWAP on
+option WRITE_USER_TRANSFORM on
+
+# graphicsmagick
+option READ_USER_CHUNKS on
+
+# Qt5.15 qtgui (gentoo package split) Qt6.6 qtbase
+option READ_BGR on
+option WRITE_BGR on
+option READ_SWAP_ALPHA on
+option WRITE_SWAP_ALPHA on
+chunk oFFs on
+
+# ghostscript-gpl
+option WRITE_INVERT_ALPHA on
+option WRITE_INVERT on

contrib/conftest/fixed.dfa

@@ -0,0 +1,15 @@
+# fixed.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Test the standard libpng configuration without floating point (the internal
+# fixed point implementations are used instead).
+#
+option FLOATING_ARITHMETIC off
+option FLOATING_POINT off

contrib/conftest/float-fixed.dfa

@@ -0,0 +1,14 @@
+# fixed-float.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Test the standard libpng configuration with the fixed point internal
+# implementation in place of the default floating point
+#
+option FLOATING_ARITHMETIC off

contrib/conftest/nocompile-limits.dfa

@@ -0,0 +1,21 @@
+# nolimits.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+#
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng without any limits and without run-time settable limits.  Turning
+# USER_LIMITS off reduces libpng code size by allowing compile-time elimination
+# of some checking code.
+#
+option USER_LIMITS off
+
+@# define PNG_USER_WIDTH_MAX PNG_UINT_31_MAX
+@# define PNG_USER_HEIGHT_MAX PNG_UINT_31_MAX
+@# define PNG_USER_CHUNK_CACHE_MAX 0
+@# define PNG_USER_CHUNK_MALLOC_MAX 0

contrib/conftest/nolimits.dfa

@@ -0,0 +1,19 @@
+# nolimits.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+#
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng without any limits.  With these settigs run-time limits are still
+# possible.
+#
+@# define PNG_USER_WIDTH_MAX PNG_UINT_31_MAX
+@# define PNG_USER_HEIGHT_MAX PNG_UINT_31_MAX
+@# define PNG_USER_CHUNK_CACHE_MAX 0
+@# define PNG_USER_CHUNK_MALLOC_MAX 0
+

contrib/conftest/pngcp.dfa

@@ -52,6 +52,6 @@ option TEXT on
 option USER_LIMITS on
 option SET_USER_LIMITS on
 
-# these are are just required for specific customizations
+# these are just required for specific customizations
 option WRITE_CUSTOMIZE_ZTXT_COMPRESSION on
 option WRITE_CUSTOMIZE_COMPRESSION on

contrib/conftest/read-full.dfa

@@ -0,0 +1,13 @@
+# read-full.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with no write support and full read support.
+#
+option WRITE off

contrib/conftest/write-full.dfa

@@ -0,0 +1,13 @@
+# write-full.dfa
+#  Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2025
+# Usage rights:
+#  To the extent possible under law, the author has waived all copyright and
+#  related or neighboring rights to this work.  This work is published from:
+#  United States.
+#
+# Build libpng with no read support and full write support.
+#
+option READ off

contrib/examples/.clang-format

@@ -0,0 +1,143 @@
+---
+Language: Cpp
+AccessModifierOffset: -3
+AlignAfterOpenBracket: Align
+AlignArrayOfStructures: None
+AlignConsecutiveAssignments:
+  Enabled: false
+AlignConsecutiveBitFields:
+  Enabled: false
+AlignConsecutiveDeclarations:
+  Enabled: false
+AlignConsecutiveMacros:
+  Enabled: false
+AlignConsecutiveShortCaseStatements:
+  Enabled: false
+AlignEscapedNewlines: DontAlign
+AlignOperands: false
+AlignTrailingComments:
+  Kind: Never
+  OverEmptyLines: 0
+AllowAllArgumentsOnNextLine: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowBreakBeforeNoexceptSpecifier: Never
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseExpressionOnASingleLine: true
+AllowShortCaseLabelsOnASingleLine: true
+AllowShortCompoundRequirementOnASingleLine: true
+AllowShortEnumsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLambdasOnASingleLine: All
+AllowShortLoopsOnASingleLine: false
+AllowShortNamespacesOnASingleLine: false
+AlwaysBreakBeforeMultilineStrings: false
+BinPackArguments: true
+BinPackParameters: BinPack
+BitFieldColonSpacing: Both
+BraceWrapping:
+  AfterCaseLabel: true
+  AfterClass: true
+  AfterControlStatement: Always
+  AfterEnum: true
+  AfterExternBlock: false
+  AfterFunction: true
+  AfterNamespace: false
+  AfterObjCDeclaration: true
+  AfterStruct: true
+  AfterUnion: true
+  BeforeCatch: true
+  BeforeElse: true
+  BeforeLambdaBody: false
+  BeforeWhile: false
+  IndentBraces: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakAdjacentStringLiterals: true
+BreakAfterAttributes: Leave
+BreakAfterJavaFieldAnnotations: false
+BreakAfterReturnType: TopLevel
+BreakArrays: true
+BreakBeforeBinaryOperators: None
+BreakBeforeConceptDeclarations: Always
+BreakBeforeBraces: Custom
+BreakBeforeTernaryOperators: false
+BreakStringLiterals: false
+BreakTemplateDeclarations: MultiLine
+ColumnLimit: 79
+ContinuationIndentWidth: 3
+DerivePointerAlignment: true
+EmptyLineAfterAccessModifier: Never
+EmptyLineBeforeAccessModifier: LogicalBlock
+FixNamespaceComments: true
+IncludeBlocks: Preserve
+IndentAccessModifiers: false
+IndentCaseBlocks: true
+IndentCaseLabels: true
+IndentExportBlock: true
+IndentExternBlock: AfterExternBlock
+IndentGotoLabels: false
+IndentPPDirectives: None
+IndentRequiresClause: true
+IndentWidth: 3
+IndentWrappedFunctionNames: false
+KeepEmptyLines:
+  AtEndOfFile: false
+  AtStartOfBlock: false
+  AtStartOfFile: false
+KeepFormFeed: false
+MaxEmptyLinesToKeep: 2
+NamespaceIndentation: None
+PackConstructorInitializers: Never
+PointerAlignment: Left
+QualifierAlignment: Custom
+QualifierOrder: [static, inline, constexpr, const, volatile, restrict, type]
+ReferenceAlignment: Pointer
+ReflowComments: Never
+RequiresClausePosition: OwnLine
+RequiresExpressionIndentation: OuterScope
+SortIncludes: false
+SortUsingDeclarations: LexicographicNumeric
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: true
+SpaceAroundPointerQualifiers: Default
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCaseColon: false
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeJsonColon: false
+SpaceBeforeParens: ControlStatements
+SpaceBeforeParensOptions:
+  AfterControlStatements: true
+  AfterFunctionDefinitionName: false
+  AfterFunctionDeclarationName: false
+  AfterOverloadedOperator: false
+  AfterPlacementOperator: true
+  AfterRequiresInClause: false
+  AfterRequiresInExpression: false
+  BeforeNonEmptyParentheses: false
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceBeforeSquareBrackets: false
+SpaceInEmptyBlock: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles: Never
+SpacesInContainerLiterals: true
+SpacesInLineCommentPrefix:
+  Minimum: 1
+  Maximum: -1
+SpacesInParens: Never
+SpacesInParensOptions:
+  ExceptDoubleParentheses: false
+  InCStyleCasts: false
+  InConditionalStatements: false
+  InEmptyParentheses: false
+  Other: false
+SpacesInSquareBrackets: false
+Standard: Latest
+TabWidth: 8
+UseTab: Never
+WrapNamespaceBodyWithEmptyLines: Leave
+...

contrib/examples/README.txt

@@ -1,4 +1,3 @@
-
 This directory (contrib/examples) contains examples of libpng usage.
 
 NO COPYRIGHT RIGHTS ARE CLAIMED TO ANY OF THE FILES IN THIS DIRECTORY.

contrib/examples/iccfrompng.c

@@ -26,8 +26,9 @@
 
 #include <png.h>
 
-#if defined(PNG_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) && \
+#if !defined(PNG_iCCP_SUPPORTED) || !defined(PNG_READ_SUPPORTED)
-    defined (PNG_iCCP_SUPPORTED)
+#error This program requires libpng supporting the iCCP chunk and the read API
+#endif
 
 
 static int verbose = 1;
@@ -36,7 +37,8 @@ static png_byte no_profile[] = "no profile";
 static png_bytep
 extract(FILE *fp, png_uint_32 *proflen)
 {
-   png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+   png_structp png_ptr =
+      png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    png_infop info_ptr = NULL;
    png_bytep result = NULL;
 
@@ -69,7 +71,7 @@ extract(FILE *fp, png_uint_32 *proflen)
       png_bytep profile;
 
       if (png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile,
-         proflen) & PNG_INFO_iCCP)
+                       proflen) & PNG_INFO_iCCP)
       {
          result = malloc(*proflen);
          if (result != NULL)
@@ -80,7 +82,7 @@ extract(FILE *fp, png_uint_32 *proflen)
       }
 
       else
-	result = no_profile;
+         result = no_profile;
    }
 
    png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
@@ -107,7 +109,7 @@ extract_one_file(const char *filename)
             const char *ep = strrchr(filename, '.');
 
             if (ep != NULL)
-               len = ep-filename;
+               len = ep - filename;
 
             else
                len = strlen(filename);
@@ -119,14 +121,14 @@ extract_one_file(const char *filename)
             FILE *of;
 
             memcpy(output, filename, len);
-            strcpy(output+len, ".icc");
+            strcpy(output + len, ".icc");
 
             of = fopen(output, "wb");
             if (of != NULL)
             {
                if (fwrite(profile, proflen, 1, of) == 1 &&
-                  fflush(of) == 0 &&
+                   fflush(of) == 0 &&
-                  fclose(of) == 0)
+                   fclose(of) == 0)
                {
                   if (verbose)
                      printf("%s -> %s\n", filename, output);
@@ -155,12 +157,15 @@ extract_one_file(const char *filename)
       }
 
       else if (verbose && profile == no_profile)
-	printf("%s has no profile\n", filename);
+         printf("%s has no profile\n", filename);
    }
 
    else
       fprintf(stderr, "%s: could not open file\n", filename);
 
+   if (fp != NULL)
+      fclose(fp);
+
    return result;
 }
 
@@ -170,7 +175,7 @@ main(int argc, char **argv)
    int i;
    int extracted = 0;
 
-   for (i=1; i<argc; ++i)
+   for (i = 1; i < argc; ++i)
    {
       if (strcmp(argv[i], "-q") == 0)
          verbose = 0;
@@ -182,4 +187,3 @@ main(int argc, char **argv)
    /* Exit code is true if any extract succeeds */
    return extracted == 0;
 }
-#endif /* READ && STDIO && iCCP */

contrib/examples/pngpixel.c

@@ -15,8 +15,8 @@
  * images.  Normally you would call png_set_interlace_handling() to have libpng
  * deal with the interlace for you, but that obliges you to buffer half of the
  * image to assemble the interlaced rows.  In this code
- * png_set_interlace_handling() is not called and, instead, the code handles the
+ * png_set_interlace_handling() is not called and, instead, the code handles
- * interlace passes directly looking for the required pixel.
+ * the interlace passes directly looking for the required pixel.
  */
 #include <stdlib.h>
 #include <stdio.h>
@@ -27,34 +27,37 @@
  */
 #include "../../png.h"
 
-#if defined(PNG_READ_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)
+#if !defined(PNG_READ_SUPPORTED) || !defined(PNG_SEQUENTIAL_READ_SUPPORTED)
+#error This program requires libpng supporting the read and sequential read API
+#endif
+
 
 /* Return component 'c' of pixel 'x' from the given row. */
 static unsigned int
 component(png_const_bytep row, png_uint_32 x, unsigned int c,
-   unsigned int bit_depth, unsigned int channels)
+          unsigned int bit_depth, unsigned int channels)
 {
-   /* PNG images can be up to 2^31 pixels wide, but this means they can be up to
+   /* PNG images can be up to 2^31 pixels wide, which means they can be up to
-    * 2^37 bits wide (for a 64-bit pixel - the largest possible) and hence 2^34
+    * 2^37 bits wide (for a 64-bit pixel - the largest possible) and hence
-    * bytes wide.  Since the row fitted into memory, however, the following must
+    * 2^34 bytes wide.  Since the row fitted into memory, the following must
     * work:
     */
    png_uint_32 bit_offset_hi = bit_depth * ((x >> 6) * channels);
    png_uint_32 bit_offset_lo = bit_depth * ((x & 0x3f) * channels + c);
 
-   row = (png_const_bytep)(((PNG_CONST png_byte (*)[8])row) + bit_offset_hi);
+   row = (png_const_bytep)(((const png_byte(*)[8])row) + bit_offset_hi);
    row += bit_offset_lo >> 3;
    bit_offset_lo &= 0x07;
 
    /* PNG pixels are packed into bytes to put the first pixel in the highest
-    * bits of the byte and into two bytes for 16-bit values with the high 8 bits
+    * bits of the byte, and into two bytes for 16-bit values with the high
-    * first, so:
+    * 8 bits first, so:
     */
    switch (bit_depth)
    {
-      case 1: return (row[0] >> (7-bit_offset_lo)) & 0x01;
+      case 1: return (row[0] >> (7 - bit_offset_lo)) & 0x01;
-      case 2: return (row[0] >> (6-bit_offset_lo)) & 0x03;
+      case 2: return (row[0] >> (6 - bit_offset_lo)) & 0x03;
-      case 4: return (row[0] >> (4-bit_offset_lo)) & 0x0f;
+      case 4: return (row[0] >> (4 - bit_offset_lo)) & 0x0f;
       case 8: return row[0];
       case 16: return (row[0] << 8) + row[1];
       default:
@@ -71,9 +74,9 @@ component(png_const_bytep row, png_uint_32 x, unsigned int c,
  */
 static void
 print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
-   png_uint_32 x)
+            png_uint_32 x)
 {
-   PNG_CONST unsigned int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
+   unsigned int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
 
    switch (png_get_color_type(png_ptr, info_ptr))
    {
@@ -87,27 +90,29 @@ print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
        */
       case PNG_COLOR_TYPE_PALETTE:
          {
-            PNG_CONST int index = component(row, x, 0, bit_depth, 1);
+            int index = component(row, x, 0, bit_depth, 1);
             png_colorp palette = NULL;
             int num_palette = 0;
 
             if ((png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) &
-               PNG_INFO_PLTE) && num_palette > 0 && palette != NULL)
+                 PNG_INFO_PLTE) &&
+                (num_palette > 0) &&
+                (palette != NULL))
             {
                png_bytep trans_alpha = NULL;
                int num_trans = 0;
                if ((png_get_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans,
-                  NULL) & PNG_INFO_tRNS) && num_trans > 0 &&
+                                 NULL) & PNG_INFO_tRNS) &&
-                  trans_alpha != NULL)
+                   (num_trans > 0) &&
+                   (trans_alpha != NULL))
                   printf("INDEXED %u = %d %d %d %d\n", index,
-                     palette[index].red, palette[index].green,
+                         palette[index].red, palette[index].green,
-                     palette[index].blue,
+                         palette[index].blue,
-                     index < num_trans ? trans_alpha[index] : 255);
+                         index < num_trans ? trans_alpha[index] : 255);
 
                else /* no transparency */
-                  printf("INDEXED %u = %d %d %d\n", index,
+                  printf("INDEXED %u = %d %d %d\n", index, palette[index].red,
-                     palette[index].red, palette[index].green,
+                         palette[index].green, palette[index].blue);
-                     palette[index].blue);
             }
 
             else
@@ -117,20 +122,20 @@ print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
 
       case PNG_COLOR_TYPE_RGB:
          printf("RGB %u %u %u\n", component(row, x, 0, bit_depth, 3),
-            component(row, x, 1, bit_depth, 3),
+                component(row, x, 1, bit_depth, 3),
-            component(row, x, 2, bit_depth, 3));
+                component(row, x, 2, bit_depth, 3));
          return;
 
       case PNG_COLOR_TYPE_GRAY_ALPHA:
          printf("GRAY+ALPHA %u %u\n", component(row, x, 0, bit_depth, 2),
-            component(row, x, 1, bit_depth, 2));
+                component(row, x, 1, bit_depth, 2));
          return;
 
       case PNG_COLOR_TYPE_RGB_ALPHA:
          printf("RGBA %u %u %u %u\n", component(row, x, 0, bit_depth, 4),
-            component(row, x, 1, bit_depth, 4),
+                component(row, x, 1, bit_depth, 4),
-            component(row, x, 2, bit_depth, 4),
+                component(row, x, 2, bit_depth, 4),
-            component(row, x, 3, bit_depth, 4));
+                component(row, x, 3, bit_depth, 4));
          return;
 
       default:
@@ -138,7 +143,8 @@ print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
    }
 }
 
-int main(int argc, const char **argv)
+int
+main(int argc, const char **argv)
 {
    /* This program uses the default, <setjmp.h> based, libpng error handling
     * mechanism, therefore any local variable that exists before the call to
@@ -146,7 +152,7 @@ int main(int argc, const char **argv)
     * be declared with 'volatile' to ensure that their values don't get
     * destroyed by longjmp:
     */
-   volatile int result = 1/*fail*/;
+   volatile int result = 1 /*fail*/;
 
    if (argc == 4)
    {
@@ -163,8 +169,8 @@ int main(int argc, const char **argv)
           * writes error messages to stderr.  Creating the png_struct is a
           * little tricky; just copy the following code.
           */
-         png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+         png_structp png_ptr =
-            NULL, NULL, NULL);
+            png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 
          if (png_ptr != NULL)
          {
@@ -184,11 +190,11 @@ int main(int argc, const char **argv)
                      compression_method, filter_method;
                   png_bytep row_tmp;
 
-                  /* Now associate the recently opened (FILE*) with the default
+                  /* Now associate the recently opened FILE object with the
-                   * libpng initialization functions.  Sometimes libpng is
+                   * default libpng initialization functions.  Sometimes libpng
-                   * compiled without stdio support (it can be difficult to do
+                   * is compiled without stdio support (it can be difficult to
-                   * in some environments); in that case you will have to write
+                   * do in some environments); in that case you will have to
-                   * your own read callback to read data from the (FILE*).
+                   * write your own read callback to read data from the stream.
                    */
                   png_init_io(png_ptr, f);
 
@@ -202,21 +208,21 @@ int main(int argc, const char **argv)
                    * space.  In this case png_malloc is used - it will not
                    * return if memory isn't available.
                    */
-                  row = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
+                  row =
-                     info_ptr));
+                     png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
 
-                  /* To avoid the overhead of using a volatile auto copy row_tmp
+                  /* Avoid the overhead of using a volatile auto copy row_tmp
                    * to a local here - just use row for the png_free below.
                    */
                   row_tmp = row;
 
-                  /* All the information we need is in the header is returned by
+                  /* All the information we need is in the header returned by
-                   * png_get_IHDR, if this fails we can now use 'png_error' to
+                   * png_get_IHDR.  If this fails, we can use 'png_error' to
                    * signal the error and return control to the setjmp above.
                    */
                   if (png_get_IHDR(png_ptr, info_ptr, &width, &height,
-                     &bit_depth, &color_type, &interlace_method,
+                                   &bit_depth, &color_type, &interlace_method,
-                     &compression_method, &filter_method))
+                                   &compression_method, &filter_method))
                   {
                      int passes, pass;
 
@@ -242,7 +248,7 @@ int main(int argc, const char **argv)
                      /* Now read the pixels, pass-by-pass, row-by-row: */
                      png_start_read_image(png_ptr);
 
-                     for (pass=0; pass<passes; ++pass)
+                     for (pass = 0; pass < passes; ++pass)
                      {
                         png_uint_32 ystart, xstart, ystep, xstep;
                         png_uint_32 py;
@@ -299,19 +305,27 @@ int main(int argc, const char **argv)
                             * are, of course, much better ways of doing this
                             * than using a for loop:
                             */
-                           if (y == py) for (px = xstart, ppx = 0;
+                           if (y == py)
-                              px < width; px += xstep, ++ppx) if (x == px)
                            {
-                              /* 'ppx' is the index of the pixel in the row
+                              for (px = xstart, ppx = 0;
-                               * buffer.
+                                   px < width;
-                               */
+                                   px += xstep, ++ppx)
-                              print_pixel(png_ptr, info_ptr, row_tmp, ppx);
+                              {
+                                 if (x == px)
+                                 {
+                                    /* 'ppx' is the index of the pixel in the
+                                     * row buffer.
+                                     */
+                                    print_pixel(png_ptr, info_ptr, row_tmp,
+                                                ppx);
 
-                              /* Now terminate the loops early - we have
+                                    /* Now terminate the loops early - we have
-                               * found and handled the required data.
+                                     * found and handled the required data.
-                               */
+                                     */
-                              goto pass_loop_end;
+                                    goto pass_loop_end;
-                           } /* x loop */
+                                 } /* x loop */
+                              }
+                           }
                         } /* y loop */
                      } /* pass loop */
 
@@ -323,7 +337,6 @@ int main(int argc, const char **argv)
 
                   else
                      png_error(png_ptr, "pngpixel: png_get_IHDR failed");
-
                }
 
                else
@@ -349,7 +362,8 @@ int main(int argc, const char **argv)
             }
 
             else
-               fprintf(stderr, "pngpixel: out of memory allocating png_info\n");
+               fprintf(stderr,
+                       "pngpixel: out of memory allocating png_info\n");
 
             png_destroy_read_struct(&png_ptr, NULL, NULL);
          }
@@ -368,4 +382,3 @@ int main(int argc, const char **argv)
 
    return result;
 }
-#endif /* READ && SEQUENTIAL_READ */

contrib/examples/pngtopng.c

@@ -5,13 +5,11 @@
  * 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.
  *
- * This sample code is just the code from the top of 'example.c' with some error
+ * This sample code is just the code from 'example.c' with some error handling
- * handling added.  See example.c for more comments.
+ * added.  See example.c in the top-level libpng directory for more comments.
  */
 #include <stddef.h>
 #include <stdlib.h>
@@ -22,10 +20,15 @@
  * ensure the code picks up the local libpng implementation:
  */
 #include "../../png.h"
-#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && \
-    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
 
-int main(int argc, const char **argv)
+#if !defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
+    !defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+#error This program requires libpng supporting the simplified read/write API
+#endif
+
+
+int
+main(int argc, const char **argv)
 {
    int result = 1;
 
@@ -50,22 +53,22 @@ int main(int argc, const char **argv)
 
          if (buffer != NULL)
          {
-            if (png_image_finish_read(&image, NULL/*background*/, buffer,
+            if (png_image_finish_read(&image, NULL /*background*/, buffer,
-               0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
+                                      0 /*row_stride*/, NULL /*colormap */))
             {
-               if (png_image_write_to_file(&image, argv[2],
+               if (png_image_write_to_file(
-                  0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+                      &image, argv[2], 0 /*convert_to_8bit*/, buffer,
-                  NULL/*colormap*/))
+                      0 /*row_stride*/, NULL /*colormap*/))
                   result = 0;
 
                else
                   fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
-                      image.message);
+                          image.message);
             }
 
             else
                fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
-                   image.message);
+                       image.message);
 
             free(buffer);
          }
@@ -73,7 +76,7 @@ int main(int argc, const char **argv)
          else
          {
             fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
-               (unsigned long)PNG_IMAGE_SIZE(image));
+                    (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
@@ -95,4 +98,3 @@ int main(int argc, const char **argv)
 
    return result;
 }
-#endif /* READ && WRITE */

contrib/examples/simpleover.c

@@ -6,9 +6,9 @@
  * United States.
  *
  * Read several PNG files, which should have an alpha channel or transparency
- * information, and composite them together to produce one or more 16-bit linear
+ * information, and composite them together to produce one or more 16-bit
- * RGBA intermediates.  This involves doing the correct 'over' composition to
+ * linear RGBA intermediates.  This involves doing the 'over' compositing
- * combine the alpha channels and corresponding data.
+ * operation to combine the alpha channels and corresponding data.
  *
  * Finally read an output (background) PNG using the 24-bit RGB format (the
  * PNG will be composited on green (#00ff00) by default if it has an alpha
@@ -28,8 +28,8 @@
  * correctly.  Apart from the libpng Simplified API the only work done in here
  * is to combine multiple input PNG images into a single sprite; this involves
  * a Porter-Duff 'over' operation and the input PNG images may, as a result,
- * be regarded as being layered one on top of the other with the first (leftmost
+ * be regarded as being layered one on top of the other with the first
- * on the command line) being at the bottom and the last on the top.
+ * (leftmost on the command line) being at the bottom and the last on the top.
  */
 #include <stddef.h>
 #include <stdlib.h>
@@ -44,54 +44,61 @@
  */
 #include "../../png.h"
 
-#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+#if !defined(PNG_SIMPLIFIED_READ_SUPPORTED)
+#error This program requires libpng supporting the simplified read API
+#endif
 
 #define sprite_name_chars 15
-struct sprite {
+struct sprite
-   FILE         *file;
+{
-   png_uint_16p  buffer;
+   FILE *file;
-   unsigned int  width;
+   png_uint_16p buffer;
-   unsigned int  height;
+   unsigned int width;
-   char          name[sprite_name_chars+1];
+   unsigned int height;
+   char name[sprite_name_chars + 1];
 };
 
 #if 0 /* div by 65535 test program */
 #include <math.h>
 #include <stdio.h>
 
-int main(void) {
+int
+main(void)
+{
    double err = 0;
    unsigned int xerr = 0;
    unsigned int r = 32769;
+   unsigned int x = 0;
+
+   do
    {
-      unsigned int x = 0;
+      unsigned int t = x + (x >> 16) /*+ (x >> 31)*/ + r;
+      double v = x, errtest;
 
-      do {
+      if (t < x)
-         unsigned int t = x + (x >> 16) /*+ (x >> 31)*/ + r;
+      {
-         double v = x, errtest;
+         fprintf(stderr, "overflow: %u+%u -> %u\n", x, r, t);
+         return 1;
+      }
 
-         if (t < x) {
+      v /= 65535;
-            fprintf(stderr, "overflow: %u+%u -> %u\n", x, r, t);
+      errtest = v;
-            return 1;
+      t >>= 16;
+      errtest -= t;
+
+      if (errtest > err)
+      {
+         err = errtest;
+         xerr = x;
+
+         if (errtest >= .5)
+         {
+            fprintf(stderr, "error: %u/65535 = %f, not %u, error %f\n",
+                    x, v, t, errtest);
+            return 0;
          }
-
+      }
-         v /= 65535;
+   } while (++x <= 65535U * 65535U);
-         errtest = v;
-         t >>= 16;
-         errtest -= t;
-
-         if (errtest > err) {
-            err = errtest;
-            xerr = x;
-
-            if (errtest >= .5) {
-               fprintf(stderr, "error: %u/65535 = %f, not %u, error %f\n",
-                     x, v, t, errtest);
-               return 0;
-            }
-         }
-      } while (++x <= 65535U*65535U);
-   }
 
    printf("error %f @ %u\n", err, xerr);
 
@@ -101,7 +108,7 @@ int main(void) {
 
 static void
 sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
-   png_imagep image, const png_uint_16 *buffer)
+          png_imagep image, const png_uint_16 *buffer)
 {
    /* This is where the Porter-Duff 'Over' operator is evaluated; change this
     * code to change the operator (this could be parameterized).  Any other
@@ -112,8 +119,8 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
    /* Check for an x or y offset that pushes any part of the image beyond the
     * right or bottom of the sprite:
     */
-   if ((y_offset < 0 || (unsigned)/*SAFE*/y_offset < sprite->height) &&
+   if ((y_offset < 0 || /*SAFE*/ (unsigned)y_offset < sprite->height) &&
-       (x_offset < 0 || (unsigned)/*SAFE*/x_offset < sprite->width))
+       (x_offset < 0 || /*SAFE*/ (unsigned)x_offset < sprite->width))
    {
       unsigned int y = 0;
 
@@ -130,7 +137,7 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
          do
          {
             /* In and out are RGBA values, so: */
-            const png_uint_16 *in_pixel = buffer + (y * image->width + x)*4;
+            const png_uint_16 *in_pixel = buffer + (y * image->width + x) * 4;
             png_uint_32 in_alpha = in_pixel[3];
 
             /* This is the optimized Porter-Duff 'Over' operation, when the
@@ -139,10 +146,10 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
             if (in_alpha > 0)
             {
                png_uint_16 *out_pixel = sprite->buffer +
-                  ((y+y_offset) * sprite->width + (x+x_offset))*4;
+                  ((y + y_offset) * sprite->width + (x + x_offset)) * 4;
 
                /* This is the weight to apply to the output: */
-               in_alpha = 65535-in_alpha;
+               in_alpha = 65535 - in_alpha;
 
                if (in_alpha > 0)
                {
@@ -159,9 +166,9 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
                    */
                   png_uint_32 tmp;
 
-#                 define compose(c)\
+#                 define compose(c) \
-                     tmp = out_pixel[c] * in_alpha;\
+                     tmp = out_pixel[c] * in_alpha; \
-                     tmp = (tmp + (tmp >> 16) + 32769) >> 16;\
+                     tmp = (tmp + (tmp >> 16) + 32769) >> 16; \
                      out_pixel[c] = tmp + in_pixel[c]
 
                   /* The following is very vectorizable... */
@@ -172,15 +179,15 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
                }
 
                else
-                  out_pixel[0] = in_pixel[0],
+               {
-                  out_pixel[1] = in_pixel[1],
+                  out_pixel[0] = in_pixel[0];
-                  out_pixel[2] = in_pixel[2],
+                  out_pixel[1] = in_pixel[1];
+                  out_pixel[2] = in_pixel[2];
                   out_pixel[3] = in_pixel[3];
+               }
             }
-         }
+         } while (++x < image->width);
-         while (++x < image->width);
+      } while (++y < image->height);
-      }
-      while (++y < image->height);
    }
 }
 
@@ -224,9 +231,8 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
 
             if (buffer != NULL)
             {
-               if (png_image_finish_read(&image, NULL/*background*/, buffer,
+               if (png_image_finish_read(&image, NULL /*background*/, buffer,
-                  0/*row_stride*/,
+                                         0 /*row_stride*/, NULL /*colormap*/))
-                  NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
                {
                   /* This is the place where the Porter-Duff 'Over' operator
                    * needs to be done by this code.  In fact, any image
@@ -245,14 +251,14 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
                {
                   free(buffer);
                   fprintf(stderr, "simpleover: read %s: %s\n", (*argv)[0],
-                      image.message);
+                          image.message);
                }
             }
 
             else
             {
                fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
-                  (unsigned long)PNG_IMAGE_SIZE(image));
+                       (unsigned long)PNG_IMAGE_SIZE(image));
 
                /* png_image_free must be called if we abort the Simplified API
                 * read because of a problem detected in this code.  If problems
@@ -290,8 +296,9 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
       save.flags = PNG_IMAGE_FLAG_FAST;
       save.colormap_entries = 0;
 
-      if (png_image_write_to_stdio(&save, sprite->file, 1/*convert_to_8_bit*/,
+      if (png_image_write_to_stdio(&save, sprite->file, 1 /*convert_to_8_bit*/,
-          sprite->buffer, 0/*row_stride*/, NULL/*colormap*/))
+                                   sprite->buffer, 0 /*row_stride*/,
+                                   NULL /*colormap*/))
       {
          /* Success; the buffer is no longer needed: */
          free(sprite->buffer);
@@ -301,19 +308,20 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
 
       else
          fprintf(stderr, "simpleover: write sprite %s: %s\n", sprite->name,
-            save.message);
+                 save.message);
    }
 
    else
-      fprintf(stderr, "simpleover: sprite %s: could not allocate tmpfile: %s\n",
+      fprintf(stderr,
-         sprite->name, strerror(errno));
+              "simpleover: sprite %s: could not allocate tmpfile: %s\n",
+              sprite->name, strerror(errno));
 
    return 0; /* fail */
 }
 
 static int
 add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
-   int *argc, const char ***argv)
+           int *argc, const char ***argv)
 {
    /* Given a --add argument naming this sprite, perform the operations listed
     * in the following arguments.  The arguments are expected to have the form
@@ -334,13 +342,13 @@ add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
           * will fit.
           */
          if (x < 0 || y < 0 ||
-             (unsigned)/*SAFE*/x >= output->width ||
+             /*SAFE*/ (unsigned)x >= output->width ||
-             (unsigned)/*SAFE*/y >= output->height ||
+             /*SAFE*/ (unsigned)y >= output->height ||
-             sprite->width > output->width-x ||
+             sprite->width > output->width - x ||
-             sprite->height > output->height-y)
+             sprite->height > output->height - y)
          {
             fprintf(stderr, "simpleover: sprite %s @ (%d,%d) outside image\n",
-               sprite->name, x, y);
+                    sprite->name, x, y);
             /* Could just skip this, but for the moment it is an error */
             return 0; /* error */
          }
@@ -359,10 +367,10 @@ add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
             {
                in.format = PNG_FORMAT_RGB; /* force compose */
 
-               if (png_image_finish_read(&in, NULL/*background*/,
+               if (png_image_finish_read(
-                  out_buf + (y*output->width + x)*3/*RGB*/,
+                      &in, NULL /*background*/,
-                  output->width*3/*row_stride*/,
+                      out_buf + (y * output->width + x) * 3 /*RGB*/,
-                  NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
+                      output->width * 3 /*row_stride*/, NULL /*colormap*/))
                {
                   ++*argv, --*argc;
                   continue;
@@ -371,7 +379,7 @@ add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
 
             /* The read failed: */
             fprintf(stderr, "simpleover: add sprite %s: %s\n", sprite->name,
-                in.message);
+                    in.message);
             return 0; /* error */
          }
       }
@@ -379,7 +387,7 @@ add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
       else
       {
          fprintf(stderr, "simpleover: --add='%s': invalid position %s\n",
-               sprite->name, (*argv)[0]);
+                 sprite->name, (*argv)[0]);
          return 0; /* error */
       }
    }
@@ -389,10 +397,10 @@ add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
 
 static int
 simpleover_process(png_imagep output, png_bytep out_buf, int argc,
-   const char **argv)
+                   const char **argv)
 {
    int result = 1; /* success */
-#  define csprites 10/*limit*/
+#  define csprites 10 /*limit*/
 #  define str(a) #a
    int nsprites = 0;
    struct sprite sprites[csprites];
@@ -412,23 +420,25 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
             sprites[nsprites].width = sprites[nsprites].height = 0;
             sprites[nsprites].name[0] = 0;
 
-            n = sscanf(argv[0], "--sprite=%u,%u,%" str(sprite_name_chars) "s%c",
+            n = sscanf(argv[0],
-                &sprites[nsprites].width, &sprites[nsprites].height,
+                       "--sprite=%u,%u,%" str(sprite_name_chars) "s%c",
-                sprites[nsprites].name, &tombstone);
+                       &sprites[nsprites].width, &sprites[nsprites].height,
+                       sprites[nsprites].name, &tombstone);
 
             if ((n == 2 || n == 3) &&
-                sprites[nsprites].width > 0 && sprites[nsprites].height > 0)
+                (sprites[nsprites].width > 0) &&
+                (sprites[nsprites].height > 0))
             {
                size_t buf_size, tmp;
 
                /* Default a name if not given. */
                if (sprites[nsprites].name[0] == 0)
-                  sprintf(sprites[nsprites].name, "sprite-%d", nsprites+1);
+                  sprintf(sprites[nsprites].name, "sprite-%d", nsprites + 1);
 
                /* Allocate a buffer for the sprite and calculate the buffer
                 * size:
                 */
-               buf_size = sizeof (png_uint_16 [4]);
+               buf_size = sizeof(png_uint_16[4]);
                buf_size *= sprites[nsprites].width;
                buf_size *= sprites[nsprites].height;
 
@@ -437,7 +447,7 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
                tmp /= sprites[nsprites].width;
                tmp /= sprites[nsprites].height;
 
-               if (tmp == sizeof (png_uint_16 [4]))
+               if (tmp == sizeof(png_uint_16[4]))
                {
                   sprites[nsprites].buffer = malloc(buf_size);
                   /* This buffer must be initialized to transparent: */
@@ -448,7 +458,7 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
                      sprites[nsprites].file = NULL;
                      ++argv, --argc;
 
-                     if (create_sprite(sprites+nsprites++, &argc, &argv))
+                     if (create_sprite(sprites + nsprites++, &argc, &argv))
                      {
                         result = 1; /* still ok */
                         continue;
@@ -466,7 +476,8 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
             else
             {
                fprintf(stderr, "simpleover: %s: invalid sprite (%u,%u)\n",
-                  argv[0], sprites[nsprites].width, sprites[nsprites].height);
+                       argv[0],
+                       sprites[nsprites].width, sprites[nsprites].height);
                break;
             }
          }
@@ -480,7 +491,7 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
 
       else if (strncmp(argv[0], "--add=", 6) == 0)
       {
-         const char *name = argv[0]+6;
+         const char *name = argv[0] + 6;
          int isprite = nsprites;
 
          ++argv, --argc;
@@ -489,7 +500,8 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
          {
             if (strcmp(sprites[isprite].name, name) == 0)
             {
-               if (!add_sprite(output, out_buf, sprites+isprite, &argc, &argv))
+               if (!add_sprite(output, out_buf, sprites + isprite,
+                               &argc, &argv))
                   goto out; /* error in add_sprite */
 
                break;
@@ -498,7 +510,8 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
 
          if (isprite < 0) /* sprite not found */
          {
-            fprintf(stderr, "simpleover: --add='%s': sprite not found\n", name);
+            fprintf(stderr, "simpleover: --add='%s': sprite not found\n",
+                    name);
             break;
          }
       }
@@ -526,7 +539,8 @@ out:
    return result;
 }
 
-int main(int argc, const char **argv)
+int
+main(int argc, const char **argv)
 {
    int result = 1; /* default to fail */
 
@@ -536,7 +550,7 @@ int main(int argc, const char **argv)
       const char *output = NULL;
       png_image image;
 
-      if (argc > 2 && argv[2][0] != '-'/*an operation*/)
+      if (argc > 2 && argv[2][0] != '-' /*an operation*/)
       {
          output = argv[2];
          argi = 3;
@@ -558,7 +572,7 @@ int main(int argc, const char **argv)
             png_color background = {0, 0xff, 0}; /* fully saturated green */
 
             if (png_image_finish_read(&image, &background, buffer,
-               0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
+                                      0 /*row_stride*/, NULL /*colormap*/))
             {
                /* At this point png_image_finish_read has cleaned up the
                 * allocated data in png_image, and only the buffer needs to be
@@ -566,22 +580,24 @@ int main(int argc, const char **argv)
                 *
                 * Perform the remaining operations:
                 */
-               if (simpleover_process(&image, buffer, argc-argi, argv+argi))
+               if (simpleover_process(&image, buffer,
+                                      argc - argi, argv + argi))
                {
                   /* Write the output: */
                   if ((output != NULL &&
-                       png_image_write_to_file(&image, output,
+                       png_image_write_to_file(
-                        0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+                          &image, output, 0 /*convert_to_8bit*/, buffer,
-                        NULL/*colormap*/)) ||
+                          0 /*row_stride*/, NULL /*colormap*/)) ||
                       (output == NULL &&
-                       png_image_write_to_stdio(&image, stdout,
+                       png_image_write_to_stdio(
-                        0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+                          &image, stdout, 0 /*convert_to_8bit*/, buffer,
-                        NULL/*colormap*/)))
+                          0 /*row_stride*/, NULL /*colormap*/)))
                      result = 0;
 
                   else
                      fprintf(stderr, "simpleover: write %s: %s\n",
-                        output == NULL ? "stdout" : output, image.message);
+                             output == NULL ? "stdout" : output,
+                             image.message);
                }
 
                /* else simpleover_process writes an error message */
@@ -589,7 +605,7 @@ int main(int argc, const char **argv)
 
             else
                fprintf(stderr, "simpleover: read %s: %s\n", argv[1],
-                   image.message);
+                       image.message);
 
             free(buffer);
          }
@@ -597,7 +613,7 @@ int main(int argc, const char **argv)
          else
          {
             fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
-               (unsigned long)PNG_IMAGE_SIZE(image));
+                    (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
@@ -617,7 +633,8 @@ int main(int argc, const char **argv)
    else
    {
       /* Usage message */
-      fprintf(stderr,
+      fprintf(
+         stderr,
          "simpleover: usage: simpleover background.png [output.png]\n"
          "  Output 'background.png' as a 24-bit RGB PNG file in 'output.png'\n"
          "   or, if not given, stdout.  'background.png' will be composited\n"
@@ -628,13 +645,13 @@ int main(int argc, const char **argv)
          "   --sprite=width,height,name {[--at=x,y] {sprite.png}}\n"
          "    Produce a transparent sprite of size (width,height) and with\n"
          "     name 'name'.\n"
-         "    For each sprite.png composite it using a Porter-Duff 'Over'\n"
+         "    For each sprite.png composite it is using a Porter-Duff 'Over'\n"
-         "     operation at offset (x,y) in the sprite (defaulting to (0,0)).\n"
+         "     operation at offset (x,y) in the sprite, defaulting to (0,0).\n"
          "     Input PNGs will be truncated to the area of the sprite.\n"
          "\n"
          "   --add='name' {x,y}\n"
          "    Optionally, before output, composite a sprite, 'name', which\n"
-         "     must have been previously produced using --sprite, at each\n"
+         "     must have been previously produced using --sprite at each\n"
          "     offset (x,y) in the output image.  Each sprite must fit\n"
          "     completely within the output image.\n"
          "\n"
@@ -645,4 +662,3 @@ int main(int argc, const char **argv)
 
    return result;
 }
-#endif /* SIMPLIFIED_READ */

contrib/gregbook/readpng2.c

@@ -146,7 +146,7 @@ int readpng2_init(mainprog_info *mainprog_ptr)
         /* These byte strings were copied from png.h.  If a future version
          * of readpng2.c recognizes more chunks, add them to this list.
          */
-        static PNG_CONST png_byte chunks_to_process[] = {
+        static const png_byte chunks_to_process[] = {
             98,  75,  71,  68, '\0',  /* bKGD */
            103,  65,  77,  65, '\0',  /* gAMA */
            115,  82,  71,  66, '\0',  /* sRGB */