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pngpriv.h (95471B)


      1 /* pngpriv.h - private declarations for use inside libpng
      2 *
      3 * Copyright (c) 2018-2025 Cosmin Truta
      4 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
      5 * Copyright (c) 1996-1997 Andreas Dilger
      6 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
      7 *
      8 * This code is released under the libpng license.
      9 * For conditions of distribution and use, see the disclaimer
     10 * and license in png.h
     11 */
     12 
     13 /* The symbols declared in this file (including the functions declared
     14 * as extern) are PRIVATE.  They are not part of the libpng public
     15 * interface, and are not recommended for use by regular applications.
     16 * Some of them may become public in the future; others may stay private,
     17 * change in an incompatible way, or even disappear.
     18 * Although the libpng users are not forbidden to include this header,
     19 * they should be well aware of the issues that may arise from doing so.
     20 */
     21 
     22 
     23 /* pngpriv.h must be included first in each translation unit inside libpng.
     24 * On the other hand, it must not be included at all, directly or indirectly,
     25 * by any application code that uses the libpng API.
     26 */
     27 #ifndef PNGPRIV_H
     28 #  define PNGPRIV_H
     29 #else
     30 #  error Duplicate inclusion of pngpriv.h; please check the libpng source files
     31 #endif
     32 
     33 #if defined(PNG_H) || defined(PNGCONF_H) || defined(PNGLCONF_H)
     34 #  error This file must not be included by applications; please include <png.h>
     35 #endif
     36 
     37 /* Feature Test Macros.  The following are defined here to ensure that correctly
     38 * implemented libraries reveal the APIs libpng needs to build and hide those
     39 * that are not needed and potentially damaging to the compilation.
     40 *
     41 * Feature Test Macros must be defined before any system header is included (see
     42 * POSIX 1003.1 2.8.2 "POSIX Symbols."
     43 *
     44 * These macros only have an effect if the operating system supports either
     45 * POSIX 1003.1 or C99, or both.  On other operating systems (particularly
     46 * Windows/Visual Studio) there is no effect; the OS specific tests below are
     47 * still required (as of 2011-05-02.)
     48 */
     49 #ifndef _POSIX_SOURCE
     50 #  define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
     51 #endif
     52 
     53 #ifndef PNG_VERSION_INFO_ONLY
     54 /* Standard library headers not required by png.h: */
     55 #  include <stdlib.h>
     56 #  include <string.h>
     57 #endif
     58 
     59 #define PNGLIB_BUILD /*libpng is being built, not used*/
     60 
     61 /* If HAVE_CONFIG_H is defined during the build then the build system must
     62 * provide an appropriate "config.h" file on the include path.  The header file
     63 * must provide definitions as required below (search for "HAVE_CONFIG_H");
     64 * see configure.ac for more details of the requirements.  The macro
     65 * "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
     66 * 'configure'; define this macro to prevent the configure build including the
     67 * configure generated config.h.  Libpng is expected to compile without *any*
     68 * special build system support on a reasonably ANSI-C compliant system.
     69 */
     70 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
     71 #  include <config.h>
     72   /* Pick up the definition of 'restrict' from config.h if it was read: */
     73 #  define PNG_RESTRICT restrict
     74 #endif
     75 
     76 /* To support symbol prefixing it is necessary to know *before* including png.h
     77 * whether the fixed point (and maybe other) APIs are exported, because if they
     78 * are not internal definitions may be required.  This is handled below just
     79 * before png.h is included, but load the configuration now if it is available.
     80 */
     81 #include "pnglibconf.h"
     82 
     83 /* Local renames may change non-exported API functions from png.h */
     84 #if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
     85 #  include "pngprefix.h"
     86 #endif
     87 
     88 #ifdef PNG_USER_CONFIG
     89 #  include "pngusr.h"
     90   /* These should have been defined in pngusr.h */
     91 #  ifndef PNG_USER_PRIVATEBUILD
     92 #    define PNG_USER_PRIVATEBUILD "Custom libpng build"
     93 #  endif
     94 #  ifndef PNG_USER_DLLFNAME_POSTFIX
     95 #    define PNG_USER_DLLFNAME_POSTFIX "Cb"
     96 #  endif
     97 #endif
     98 
     99 /* Compile time options.
    100 * =====================
    101 * In a multi-arch build the compiler may compile the code several times for the
    102 * same object module, producing different binaries for different architectures.
    103 * When this happens configure-time setting of the target host options cannot be
    104 * done and this interferes with the handling of the ARM NEON optimizations, and
    105 * possibly other similar optimizations.  Put additional tests here; in general
    106 * this is needed when the same option can be changed at both compile time and
    107 * run time depending on the target OS (i.e. iOS vs Android.)
    108 *
    109 * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
    110 * this is not possible with certain compilers (Oracle SUN OS CC), as a result
    111 * it is necessary to ensure that all extern functions that *might* be used
    112 * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
    113 * below is one example of this behavior because it is controlled by the
    114 * presence or not of -mfpu=neon on the GCC command line, it is possible to do
    115 * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
    116 * do this.
    117 */
    118 #ifndef PNG_ARM_NEON_OPT
    119   /* ARM NEON optimizations are being controlled by the compiler settings,
    120    * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon
    121    * with GCC) then the compiler will define __ARM_NEON__ and we can rely
    122    * unconditionally on NEON instructions not crashing, otherwise we must
    123    * disable use of NEON instructions.
    124    *
    125    * NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
    126    * can only be turned on automatically if that is supported too.  If
    127    * PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
    128    * to compile with an appropriate #error if ALIGNED_MEMORY has been turned
    129    * off.
    130    *
    131    * Note that gcc-4.9 defines __ARM_NEON instead of the deprecated
    132    * __ARM_NEON__, so we check both variants.
    133    *
    134    * To disable ARM_NEON optimizations entirely, and skip compiling the
    135    * associated assembler code, pass --enable-arm-neon=no to configure
    136    * or put -DPNG_ARM_NEON_OPT=0 in CPPFLAGS.
    137    */
    138 #  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
    139   defined(PNG_ALIGNED_MEMORY_SUPPORTED)
    140 #     define PNG_ARM_NEON_OPT 2
    141 #  else
    142 #     define PNG_ARM_NEON_OPT 0
    143 #  endif
    144 #endif
    145 
    146 #ifndef PNG_RISCV_RVV_OPT
    147   /* RISCV_RVV optimizations are being controlled by the compiler settings,
    148    * typically the target compiler will define __riscv but the rvv extension
    149    * availability has to be explicitly stated. This is why if no
    150    * PNG_RISCV_RVV_OPT was defined then a runtime check will be executed.
    151    *
    152    * To enable RISCV_RVV optimizations unconditionally, and compile the
    153    * associated code, pass --enable-riscv-rvv=yes or --enable-riscv-rvv=on
    154    * to configure or put -DPNG_RISCV_RVV_OPT=2 in CPPFLAGS.
    155    */
    156 
    157 #  define PNG_RISCV_RVV_OPT 0
    158 #endif
    159 
    160 #if PNG_ARM_NEON_OPT > 0
    161   /* NEON optimizations are to be at least considered by libpng, so enable the
    162    * callbacks to do this.
    163    */
    164 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
    165 #  ifndef PNG_ARM_NEON_IMPLEMENTATION
    166      /* Use the intrinsics code by default. */
    167 #     define PNG_ARM_NEON_IMPLEMENTATION 1
    168 #  endif
    169 #else /* PNG_ARM_NEON_OPT == 0 */
    170 #     define PNG_ARM_NEON_IMPLEMENTATION 0
    171 #endif /* PNG_ARM_NEON_OPT > 0 */
    172 
    173 #ifndef PNG_MIPS_MSA_OPT
    174 #  if defined(__mips_msa) && (__mips_isa_rev >= 5) && \
    175   defined(PNG_ALIGNED_MEMORY_SUPPORTED)
    176 #     define PNG_MIPS_MSA_OPT 2
    177 #  else
    178 #     define PNG_MIPS_MSA_OPT 0
    179 #  endif
    180 #endif
    181 
    182 #ifndef PNG_MIPS_MMI_OPT
    183 #  ifdef PNG_MIPS_MMI
    184 #    if defined(__mips_loongson_mmi) && (_MIPS_SIM == _ABI64) && \
    185     defined(PNG_ALIGNED_MEMORY_SUPPORTED)
    186 #       define PNG_MIPS_MMI_OPT 1
    187 #    else
    188 #       define PNG_MIPS_MMI_OPT 0
    189 #    endif
    190 #  else
    191 #    define PNG_MIPS_MMI_OPT 0
    192 #  endif
    193 #endif
    194 
    195 #ifndef PNG_POWERPC_VSX_OPT
    196 #  if defined(__PPC64__) && defined(__ALTIVEC__) && defined(__VSX__)
    197 #     define PNG_POWERPC_VSX_OPT 2
    198 #  else
    199 #     define PNG_POWERPC_VSX_OPT 0
    200 #  endif
    201 #endif
    202 
    203 #ifndef PNG_LOONGARCH_LSX_OPT
    204 #  if defined(__loongarch_sx)
    205 #     define PNG_LOONGARCH_LSX_OPT 1
    206 #  else
    207 #     define PNG_LOONGARCH_LSX_OPT 0
    208 #  endif
    209 #endif
    210 
    211 #ifndef PNG_INTEL_SSE_OPT
    212 #   ifdef PNG_INTEL_SSE
    213      /* Only check for SSE if the build configuration has been modified to
    214       * enable SSE optimizations.  This means that these optimizations will
    215       * be off by default.  See contrib/intel for more details.
    216       */
    217 #      if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
    218       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
    219       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
    220 #         define PNG_INTEL_SSE_OPT 1
    221 #      else
    222 #         define PNG_INTEL_SSE_OPT 0
    223 #      endif
    224 #   else
    225 #      define PNG_INTEL_SSE_OPT 0
    226 #   endif
    227 #endif
    228 
    229 #if PNG_INTEL_SSE_OPT > 0
    230 #   ifndef PNG_INTEL_SSE_IMPLEMENTATION
    231 #      if defined(__SSE4_1__) || defined(__AVX__)
    232          /* We are not actually using AVX, but checking for AVX is the best
    233             way we can detect SSE4.1 and SSSE3 on MSVC.
    234          */
    235 #         define PNG_INTEL_SSE_IMPLEMENTATION 3
    236 #      elif defined(__SSSE3__)
    237 #         define PNG_INTEL_SSE_IMPLEMENTATION 2
    238 #      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
    239       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
    240 #         define PNG_INTEL_SSE_IMPLEMENTATION 1
    241 #      else
    242 #         define PNG_INTEL_SSE_IMPLEMENTATION 0
    243 #      endif
    244 #   endif
    245 
    246 #   if PNG_INTEL_SSE_IMPLEMENTATION > 0
    247 #      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
    248 #   endif
    249 #else
    250 #   define PNG_INTEL_SSE_IMPLEMENTATION 0
    251 #endif
    252 
    253 #if PNG_MIPS_MSA_OPT > 0
    254 #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
    255 #     if defined(__mips_msa)
    256 #        if defined(__clang__)
    257 #        elif defined(__GNUC__)
    258 #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
    259 #              define PNG_MIPS_MSA_IMPLEMENTATION 2
    260 #           endif /* no GNUC support */
    261 #        endif /* __GNUC__ */
    262 #     else /* !defined __mips_msa */
    263 #        define PNG_MIPS_MSA_IMPLEMENTATION 2
    264 #     endif /* __mips_msa */
    265 #  endif /* !PNG_MIPS_MSA_IMPLEMENTATION */
    266 
    267 #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
    268 #     define PNG_MIPS_MSA_IMPLEMENTATION 1
    269 #     define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_mips
    270 #  endif
    271 #else
    272 #  define PNG_MIPS_MSA_IMPLEMENTATION 0
    273 #endif /* PNG_MIPS_MSA_OPT > 0 */
    274 
    275 #if PNG_MIPS_MMI_OPT > 0
    276 #  ifndef PNG_MIPS_MMI_IMPLEMENTATION
    277 #     if defined(__mips_loongson_mmi) && (_MIPS_SIM == _ABI64)
    278 #        define PNG_MIPS_MMI_IMPLEMENTATION 2
    279 #     else /* !defined __mips_loongson_mmi  || _MIPS_SIM != _ABI64 */
    280 #        define PNG_MIPS_MMI_IMPLEMENTATION 0
    281 #     endif /* __mips_loongson_mmi  && _MIPS_SIM == _ABI64 */
    282 #  endif /* !PNG_MIPS_MMI_IMPLEMENTATION */
    283 
    284 #   if PNG_MIPS_MMI_IMPLEMENTATION > 0
    285 #      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_mips
    286 #   endif
    287 #else
    288 #   define PNG_MIPS_MMI_IMPLEMENTATION 0
    289 #endif /* PNG_MIPS_MMI_OPT > 0 */
    290 
    291 #if PNG_POWERPC_VSX_OPT > 0
    292 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
    293 #  define PNG_POWERPC_VSX_IMPLEMENTATION 1
    294 #else
    295 #  define PNG_POWERPC_VSX_IMPLEMENTATION 0
    296 #endif
    297 
    298 #if PNG_LOONGARCH_LSX_OPT > 0
    299 #   define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_lsx
    300 #   define PNG_LOONGARCH_LSX_IMPLEMENTATION 1
    301 #else
    302 #   define PNG_LOONGARCH_LSX_IMPLEMENTATION 0
    303 #endif
    304 
    305 #if PNG_RISCV_RVV_OPT > 0 && __riscv_v >= 1000000
    306 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_rvv
    307 #  ifndef PNG_RISCV_RVV_IMPLEMENTATION
    308      /* Use the intrinsics code by default. */
    309 #     define PNG_RISCV_RVV_IMPLEMENTATION 1
    310 #  endif
    311 #else
    312 #  define PNG_RISCV_RVV_IMPLEMENTATION 0
    313 #endif /* PNG_RISCV_RVV_OPT > 0 && __riscv_v >= 1000000 */
    314 
    315 /* Is this a build of a DLL where compilation of the object modules requires
    316 * different preprocessor settings to those required for a simple library?  If
    317 * so PNG_BUILD_DLL must be set.
    318 *
    319 * If libpng is used inside a DLL but that DLL does not export the libpng APIs
    320 * PNG_BUILD_DLL must not be set.  To avoid the code below kicking in build a
    321 * static library of libpng then link the DLL against that.
    322 */
    323 #ifndef PNG_BUILD_DLL
    324 #  ifdef DLL_EXPORT
    325      /* This is set by libtool when files are compiled for a DLL; libtool
    326       * always compiles twice, even on systems where it isn't necessary.  Set
    327       * PNG_BUILD_DLL in case it is necessary:
    328       */
    329 #     define PNG_BUILD_DLL
    330 #  else
    331 #     ifdef _WINDLL
    332         /* This is set by the Microsoft Visual Studio IDE in projects that
    333          * build a DLL.  It can't easily be removed from those projects (it
    334          * isn't visible in the Visual Studio UI) so it is a fairly reliable
    335          * indication that PNG_IMPEXP needs to be set to the DLL export
    336          * attributes.
    337          */
    338 #        define PNG_BUILD_DLL
    339 #     else
    340 #        ifdef __DLL__
    341            /* This is set by the Borland C system when compiling for a DLL
    342             * (as above.)
    343             */
    344 #           define PNG_BUILD_DLL
    345 #        else
    346            /* Add additional compiler cases here. */
    347 #        endif
    348 #     endif
    349 #  endif
    350 #endif /* Setting PNG_BUILD_DLL if required */
    351 
    352 /* See pngconf.h for more details: the builder of the library may set this on
    353 * the command line to the right thing for the specific compilation system or it
    354 * may be automagically set above (at present we know of no system where it does
    355 * need to be set on the command line.)
    356 *
    357 * PNG_IMPEXP must be set here when building the library to prevent pngconf.h
    358 * setting it to the "import" setting for a DLL build.
    359 */
    360 #ifndef PNG_IMPEXP
    361 #  ifdef PNG_BUILD_DLL
    362 #     define PNG_IMPEXP PNG_DLL_EXPORT
    363 #  else
    364      /* Not building a DLL, or the DLL doesn't require specific export
    365       * definitions.
    366       */
    367 #     define PNG_IMPEXP
    368 #  endif
    369 #endif
    370 
    371 /* No warnings for private or deprecated functions in the build: */
    372 #ifndef PNG_DEPRECATED
    373 #  define PNG_DEPRECATED
    374 #endif
    375 #ifndef PNG_PRIVATE
    376 #  define PNG_PRIVATE
    377 #endif
    378 
    379 /* Symbol preprocessing support.
    380 *
    381 * To enable listing global, but internal, symbols the following macros should
    382 * always be used to declare an extern data or function object in this file.
    383 */
    384 #ifndef PNG_INTERNAL_DATA
    385 #  define PNG_INTERNAL_DATA(type, name, array) PNG_LINKAGE_DATA type name array
    386 #endif
    387 
    388 #ifndef PNG_INTERNAL_FUNCTION
    389 #  define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
    390      PNG_LINKAGE_FUNCTION PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
    391 #endif
    392 
    393 #ifndef PNG_INTERNAL_CALLBACK
    394 #  define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
    395      PNG_LINKAGE_CALLBACK PNG_FUNCTION(type, (PNGCBAPI name), args,\
    396         PNG_EMPTY attributes)
    397 #endif
    398 
    399 /* If floating or fixed point APIs are disabled they may still be compiled
    400 * internally.  To handle this make sure they are declared as the appropriate
    401 * internal extern function (otherwise the symbol prefixing stuff won't work and
    402 * the functions will be used without definitions.)
    403 *
    404 * NOTE: although all the API functions are declared here they are not all
    405 * actually built!  Because the declarations are still made it is necessary to
    406 * fake out types that they depend on.
    407 */
    408 #ifndef PNG_FP_EXPORT
    409 #  ifndef PNG_FLOATING_POINT_SUPPORTED
    410 #     define PNG_FP_EXPORT(ordinal, type, name, args)\
    411         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
    412 #     ifndef PNG_VERSION_INFO_ONLY
    413         typedef struct png_incomplete png_double;
    414         typedef png_double*           png_doublep;
    415         typedef const png_double*     png_const_doublep;
    416         typedef png_double**          png_doublepp;
    417 #     endif
    418 #  endif
    419 #endif
    420 #ifndef PNG_FIXED_EXPORT
    421 #  ifndef PNG_FIXED_POINT_SUPPORTED
    422 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
    423         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
    424 #  endif
    425 #endif
    426 
    427 #include "png.h"
    428 
    429 /* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
    430 #ifndef PNG_DLL_EXPORT
    431 #  define PNG_DLL_EXPORT
    432 #endif
    433 
    434 /* This is a global switch to set the compilation for an installed system
    435 * (a release build).  It can be set for testing debug builds to ensure that
    436 * they will compile when the build type is switched to RC or STABLE, the
    437 * default is just to use PNG_LIBPNG_BUILD_BASE_TYPE.  Set this in CPPFLAGS
    438 * with either:
    439 *
    440 *   -DPNG_RELEASE_BUILD Turns on the release compile path
    441 *   -DPNG_RELEASE_BUILD=0 Turns it off
    442 * or in your pngusr.h with
    443 *   #define PNG_RELEASE_BUILD=1 Turns on the release compile path
    444 *   #define PNG_RELEASE_BUILD=0 Turns it off
    445 */
    446 #ifndef PNG_RELEASE_BUILD
    447 #  define PNG_RELEASE_BUILD (PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC)
    448 #endif
    449 
    450 /* SECURITY and SAFETY:
    451 *
    452 * libpng is built with support for internal limits on image dimensions and
    453 * memory usage.  These are documented in scripts/pnglibconf.dfa of the
    454 * source and recorded in the machine generated header file pnglibconf.h.
    455 */
    456 
    457 /* If you are running on a machine where you cannot allocate more
    458 * than 64K of memory at once, uncomment this.  While libpng will not
    459 * normally need that much memory in a chunk (unless you load up a very
    460 * large file), zlib needs to know how big of a chunk it can use, and
    461 * libpng thus makes sure to check any memory allocation to verify it
    462 * will fit into memory.
    463 *
    464 * zlib provides 'MAXSEG_64K' which, if defined, indicates the
    465 * same limit and pngconf.h (already included) sets the limit
    466 * if certain operating systems are detected.
    467 */
    468 #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
    469 #  define PNG_MAX_MALLOC_64K
    470 #endif
    471 
    472 #ifndef PNG_UNUSED
    473 /* Unused formal parameter warnings are silenced using the following macro
    474 * which is expected to have no bad effects on performance (optimizing
    475 * compilers will probably remove it entirely).  Note that if you replace
    476 * it with something other than whitespace, you must include the terminating
    477 * semicolon.
    478 */
    479 #  define PNG_UNUSED(param) (void)param;
    480 #endif
    481 
    482 /* Just a little check that someone hasn't tried to define something
    483 * contradictory.
    484 */
    485 #if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
    486 #  undef PNG_ZBUF_SIZE
    487 #  define PNG_ZBUF_SIZE 65536L
    488 #endif
    489 
    490 /* If warnings or errors are turned off the code is disabled or redirected here.
    491 * From 1.5.4 functions have been added to allow very limited formatting of
    492 * error and warning messages - this code will also be disabled here.
    493 */
    494 #ifdef PNG_WARNINGS_SUPPORTED
    495 #  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
    496 #else
    497 #  define png_warning_parameter(p,number,string) ((void)0)
    498 #  define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
    499 #  define png_warning_parameter_signed(p,number,format,value) ((void)0)
    500 #  define png_formatted_warning(pp,p,message) ((void)(pp))
    501 #  define PNG_WARNING_PARAMETERS(p)
    502 #endif
    503 #ifndef PNG_ERROR_TEXT_SUPPORTED
    504 #  define png_fixed_error(s1,s2) png_err(s1)
    505 #endif
    506 
    507 /* Some fixed point APIs are still required even if not exported because
    508 * they get used by the corresponding floating point APIs.  This magic
    509 * deals with this:
    510 */
    511 #ifdef PNG_FIXED_POINT_SUPPORTED
    512 #  define PNGFAPI PNGAPI
    513 #else
    514 #  define PNGFAPI /* PRIVATE */
    515 #endif
    516 
    517 #ifndef PNG_VERSION_INFO_ONLY
    518 /* Other defines specific to compilers can go here.  Try to keep
    519 * them inside an appropriate ifdef/endif pair for portability.
    520 */
    521 
    522 /* C allows up-casts from (void*) to any pointer and (const void*) to any
    523 * pointer to a const object.  C++ regards this as a type error and requires an
    524 * explicit, static, cast and provides the static_cast<> rune to ensure that
    525 * const is not cast away.
    526 */
    527 #ifdef __cplusplus
    528 #  define png_voidcast(type, value) static_cast<type>(value)
    529 #  define png_constcast(type, value) const_cast<type>(value)
    530 #  define png_aligncast(type, value) \
    531   static_cast<type>(static_cast<void*>(value))
    532 #  define png_aligncastconst(type, value) \
    533   static_cast<type>(static_cast<const void*>(value))
    534 #else
    535 #  define png_voidcast(type, value) (value)
    536 #  define png_constcast(type, value) ((type)(void*)(const void*)(value))
    537 #  define png_aligncast(type, value) ((void*)(value))
    538 #  define png_aligncastconst(type, value) ((const void*)(value))
    539 #endif /* __cplusplus */
    540 
    541 #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
    542    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
    543   /* png.c requires the following ANSI-C constants if the conversion of
    544    * floating point to ASCII is implemented therein:
    545    *
    546    *  DBL_DIG  Maximum number of decimal digits (can be set to any constant)
    547    *  DBL_MIN  Smallest normalized fp number (can be set to an arbitrary value)
    548    *  DBL_MAX  Maximum floating point number (can be set to an arbitrary value)
    549    */
    550 #  include <float.h>
    551 
    552 #  include <math.h>
    553 
    554 #  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
    555   /* Amiga SAS/C: We must include builtin FPU functions when compiling using
    556    * MATH=68881
    557    */
    558 #    include <m68881.h>
    559 #  endif
    560 #endif
    561 
    562 /* This provides the non-ANSI (far) memory allocation routines. */
    563 #if defined(__TURBOC__) && defined(__MSDOS__)
    564 #  include <mem.h>
    565 #  include <alloc.h>
    566 #endif
    567 
    568 #if defined(_WIN32) || defined(__WIN32__) || defined(__NT__)
    569 #  include <windows.h>
    570 #endif
    571 #endif /* PNG_VERSION_INFO_ONLY */
    572 
    573 /* Moved here around 1.5.0beta36 from pngconf.h */
    574 /* Users may want to use these so they are not private.  Any library
    575 * functions that are passed far data must be model-independent.
    576 */
    577 
    578 /* Platform-independent functions */
    579 #ifndef PNG_ABORT
    580 #  define PNG_ABORT() abort()
    581 #endif
    582 
    583 /* These macros may need to be architecture dependent. */
    584 #define PNG_ALIGN_NONE      0 /* do not use data alignment */
    585 #define PNG_ALIGN_ALWAYS    1 /* assume unaligned accesses are OK */
    586 #ifdef offsetof
    587 #  define PNG_ALIGN_OFFSET  2 /* use offsetof to determine alignment */
    588 #else
    589 #  define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
    590 #endif
    591 #define PNG_ALIGN_SIZE      3 /* use sizeof to determine alignment */
    592 
    593 #ifndef PNG_ALIGN_TYPE
    594   /* Default to using aligned access optimizations and requiring alignment to a
    595    * multiple of the data type size.  Override in a compiler specific fashion
    596    * if necessary by inserting tests here:
    597    */
    598 #  define PNG_ALIGN_TYPE PNG_ALIGN_SIZE
    599 #endif
    600 
    601 #if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
    602   /* This is used because in some compiler implementations non-aligned
    603    * structure members are supported, so the offsetof approach below fails.
    604    * Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
    605    * is good for performance.  Do not do this unless you have tested the
    606    * result and understand it.
    607    */
    608 #  define png_alignof(type) (sizeof(type))
    609 #else
    610 #  if PNG_ALIGN_TYPE == PNG_ALIGN_OFFSET
    611 #    define png_alignof(type) offsetof(struct{char c; type t;}, t)
    612 #  else
    613 #    if PNG_ALIGN_TYPE == PNG_ALIGN_ALWAYS
    614 #      define png_alignof(type) 1
    615 #    endif
    616     /* Else leave png_alignof undefined to prevent use thereof */
    617 #  endif
    618 #endif
    619 
    620 /* This implicitly assumes alignment is always a multiple of 2. */
    621 #ifdef png_alignof
    622 #  define png_isaligned(ptr, type) \
    623   (((type)(size_t)((const void*)(ptr)) & (type)(png_alignof(type)-1)) == 0)
    624 #else
    625 #  define png_isaligned(ptr, type) 0
    626 #endif
    627 
    628 /* End of memory model/platform independent support */
    629 /* End of 1.5.0beta36 move from pngconf.h */
    630 
    631 /* CONSTANTS and UTILITY MACROS
    632 * These are used internally by libpng and not exposed in the API
    633 */
    634 
    635 /* Various modes of operation.  Note that after an init, mode is set to
    636 * zero automatically when the structure is created.  Three of these
    637 * are defined in png.h because they need to be visible to applications
    638 * that call png_set_unknown_chunk().
    639 */
    640 /* #define PNG_HAVE_IHDR            0x01U (defined in png.h) */
    641 /* #define PNG_HAVE_PLTE            0x02U (defined in png.h) */
    642 #define PNG_HAVE_IDAT               0x04U
    643 /* #define PNG_AFTER_IDAT           0x08U (defined in png.h) */
    644 #define PNG_HAVE_IEND               0x10U
    645                   /*               0x20U (unused) */
    646                   /*               0x40U (unused) */
    647                   /*               0x80U (unused) */
    648 #define PNG_HAVE_CHUNK_HEADER      0x100U
    649 #define PNG_WROTE_tIME             0x200U
    650 #define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
    651 #define PNG_BACKGROUND_IS_GRAY     0x800U
    652 #define PNG_HAVE_PNG_SIGNATURE    0x1000U
    653 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
    654 #define PNG_WROTE_eXIf            0x4000U
    655 #define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
    656 #ifdef PNG_APNG_SUPPORTED
    657 #define PNG_HAVE_acTL            0x10000U
    658 #define PNG_HAVE_fcTL            0x20000U
    659 #endif
    660 
    661 /* Flags for the transformations the PNG library does on the image data */
    662 #define PNG_BGR                 0x0001U
    663 #define PNG_INTERLACE           0x0002U
    664 #define PNG_PACK                0x0004U
    665 #define PNG_SHIFT               0x0008U
    666 #define PNG_SWAP_BYTES          0x0010U
    667 #define PNG_INVERT_MONO         0x0020U
    668 #define PNG_QUANTIZE            0x0040U
    669 #define PNG_COMPOSE             0x0080U    /* Was PNG_BACKGROUND */
    670 #define PNG_BACKGROUND_EXPAND   0x0100U
    671 #define PNG_EXPAND_16           0x0200U    /* Added to libpng 1.5.2 */
    672 #define PNG_16_TO_8             0x0400U    /* Becomes 'chop' in 1.5.4 */
    673 #define PNG_RGBA                0x0800U
    674 #define PNG_EXPAND              0x1000U
    675 #define PNG_GAMMA               0x2000U
    676 #define PNG_GRAY_TO_RGB         0x4000U
    677 #define PNG_FILLER              0x8000U
    678 #define PNG_PACKSWAP           0x10000U
    679 #define PNG_SWAP_ALPHA         0x20000U
    680 #define PNG_STRIP_ALPHA        0x40000U
    681 #define PNG_INVERT_ALPHA       0x80000U
    682 #define PNG_USER_TRANSFORM    0x100000U
    683 #define PNG_RGB_TO_GRAY_ERR   0x200000U
    684 #define PNG_RGB_TO_GRAY_WARN  0x400000U
    685 #define PNG_RGB_TO_GRAY       0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
    686 #define PNG_ENCODE_ALPHA      0x800000U /* Added to libpng-1.5.4 */
    687 #define PNG_ADD_ALPHA        0x1000000U /* Added to libpng-1.2.7 */
    688 #define PNG_EXPAND_tRNS      0x2000000U /* Added to libpng-1.2.9 */
    689 #define PNG_SCALE_16_TO_8    0x4000000U /* Added to libpng-1.5.4 */
    690                       /*    0x8000000U unused */
    691                       /*   0x10000000U unused */
    692                       /*   0x20000000U unused */
    693                       /*   0x40000000U unused */
    694 /* Flags for png_create_struct */
    695 #define PNG_STRUCT_PNG   0x0001U
    696 #define PNG_STRUCT_INFO  0x0002U
    697 
    698 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
    699 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001U
    700 #define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002U /* Added to libpng-1.6.0 */
    701                                  /*      0x0004U    unused */
    702 #define PNG_FLAG_ZSTREAM_ENDED            0x0008U /* Added to libpng-1.6.0 */
    703                                  /*      0x0010U    unused */
    704                                  /*      0x0020U    unused */
    705 #define PNG_FLAG_ROW_INIT                 0x0040U
    706 #define PNG_FLAG_FILLER_AFTER             0x0080U
    707 #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100U
    708 #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200U
    709 #define PNG_FLAG_CRC_CRITICAL_USE         0x0400U
    710 #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800U
    711 /*      PNG_FLAG_ASSUME_sRGB unused       0x1000U  * Added to libpng-1.5.4 */
    712 #define PNG_FLAG_OPTIMIZE_ALPHA           0x2000U /* Added to libpng-1.5.4 */
    713 #define PNG_FLAG_DETECT_UNINITIALIZED     0x4000U /* Added to libpng-1.5.4 */
    714 /* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000U */
    715 /* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000U */
    716 #define PNG_FLAG_LIBRARY_MISMATCH        0x20000U
    717                                  /*     0x40000U    unused */
    718 #define PNG_FLAG_STRIP_ERROR_TEXT        0x80000U
    719 #define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000U /* Added to libpng-1.4.0 */
    720 #define PNG_FLAG_APP_WARNINGS_WARN      0x200000U /* Added to libpng-1.6.0 */
    721 #define PNG_FLAG_APP_ERRORS_WARN        0x400000U /* Added to libpng-1.6.0 */
    722                                  /*    0x800000U    unused */
    723                                  /*   0x1000000U    unused */
    724                                  /*   0x2000000U    unused */
    725                                  /*   0x4000000U    unused */
    726                                  /*   0x8000000U    unused */
    727                                  /*  0x10000000U    unused */
    728                                  /*  0x20000000U    unused */
    729                                  /*  0x40000000U    unused */
    730 
    731 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
    732                                     PNG_FLAG_CRC_ANCILLARY_NOWARN)
    733 
    734 #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
    735                                     PNG_FLAG_CRC_CRITICAL_IGNORE)
    736 
    737 #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
    738                                     PNG_FLAG_CRC_CRITICAL_MASK)
    739 
    740 /* Save typing and make code easier to understand */
    741 
    742 #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
    743   abs((int)((c1).green) - (int)((c2).green)) + \
    744   abs((int)((c1).blue) - (int)((c2).blue)))
    745 
    746 /* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
    747 * by dividing by 257 *with rounding*.  This macro is exact for the given range.
    748 * See the discourse in pngrtran.c png_do_scale_16_to_8.  The values in the
    749 * macro were established by experiment (modifying the added value).  The macro
    750 * has a second variant that takes a value already scaled by 255 and divides by
    751 * 65535 - this has a maximum error of .502.  Over the range 0..65535*65535 it
    752 * only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
    753 */
    754 #define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
    755 #define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)
    756 
    757 /* Added to libpng-1.2.6 JB */
    758 #define PNG_ROWBYTES(pixel_bits, width) \
    759    ((pixel_bits) >= 8 ? \
    760    ((size_t)(width) * (((size_t)(pixel_bits)) >> 3)) : \
    761    (( ((size_t)(width) * ((size_t)(pixel_bits))) + 7) >> 3) )
    762 
    763 /* This returns the number of trailing bits in the last byte of a row, 0 if the
    764 * last byte is completely full of pixels.  It is, in principle, (pixel_bits x
    765 * width) % 8, but that would overflow for large 'width'.  The second macro is
    766 * the same except that it returns the number of unused bits in the last byte;
    767 * (8-TRAILBITS), but 0 when TRAILBITS is 0.
    768 *
    769 * NOTE: these macros are intended to be self-evidently correct and never
    770 * overflow on the assumption that pixel_bits is in the range 0..255.  The
    771 * arguments are evaluated only once and they can be signed (e.g. as a result of
    772 * the integral promotions).  The result of the expression always has type
    773 * (png_uint_32), however the compiler always knows it is in the range 0..7.
    774 */
    775 #define PNG_TRAILBITS(pixel_bits, width) \
    776    (((pixel_bits) * ((width) % (png_uint_32)8)) % 8)
    777 
    778 #define PNG_PADBITS(pixel_bits, width) \
    779    ((8 - PNG_TRAILBITS(pixel_bits, width)) % 8)
    780 
    781 /* PNG_OUT_OF_RANGE returns true if value is outside the range
    782 * ideal-delta..ideal+delta.  Each argument is evaluated twice.
    783 * "ideal" and "delta" should be constants, normally simple
    784 * integers, "value" a variable. Added to libpng-1.2.6 JB
    785 */
    786 #define PNG_OUT_OF_RANGE(value, ideal, delta) \
    787   ( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
    788 
    789 /* Conversions between fixed and floating point, only defined if
    790 * required (to make sure the code doesn't accidentally use float
    791 * when it is supposedly disabled.)
    792 */
    793 #ifdef PNG_FLOATING_POINT_SUPPORTED
    794 /* The floating point conversion can't overflow, though it can and
    795 * does lose accuracy relative to the original fixed point value.
    796 * In practice this doesn't matter because png_fixed_point only
    797 * stores numbers with very low precision.  The png_ptr and s
    798 * arguments are unused by default but are there in case error
    799 * checking becomes a requirement.
    800 */
    801 #define png_float(png_ptr, fixed, s) (.00001 * (fixed))
    802 
    803 /* The fixed point conversion performs range checking and evaluates
    804 * its argument multiple times, so must be used with care.  The
    805 * range checking uses the PNG specification values for a signed
    806 * 32-bit fixed point value except that the values are deliberately
    807 * rounded-to-zero to an integral value - 21474 (21474.83 is roughly
    808 * (2^31-1) * 100000). 's' is a string that describes the value being
    809 * converted.
    810 *
    811 * NOTE: this macro will raise a png_error if the range check fails,
    812 * therefore it is normally only appropriate to use this on values
    813 * that come from API calls or other sources where an out of range
    814 * error indicates a programming error, not a data error!
    815 *
    816 * NOTE: by default this is off - the macro is not used - because the
    817 * function call saves a lot of code.
    818 */
    819 #ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
    820 #define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
    821    ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
    822 #define png_fixed_ITU(png_ptr, fp, s) ((fp) <= 214748 && (fp) >= 0 ?\
    823    ((png_uint_32)(10000 * (fp))) : (png_fixed_error(png_ptr, s),0))
    824 #endif
    825 /* else the corresponding function is defined below, inside the scope of the
    826 * cplusplus test.
    827 */
    828 #endif
    829 
    830 /* Constants for known chunk types.  If you need to add a chunk, define the name
    831 * here.  For historical reasons these constants have the form png_<name>; i.e.
    832 * the prefix is lower case.  Please use decimal values as the parameters to
    833 * match the ISO PNG specification and to avoid relying on the C locale
    834 * interpretation of character values.
    835 *
    836 * Prior to 1.5.6 these constants were strings, as of 1.5.6 png_uint_32 values
    837 * are computed and a new macro (PNG_STRING_FROM_CHUNK) added to allow a string
    838 * to be generated if required.
    839 *
    840 * PNG_32b correctly produces a value shifted by up to 24 bits, even on
    841 * architectures where (int) is only 16 bits.
    842 *
    843 * 1.6.47: PNG_32b was made into a preprocessor evaluable macro by replacing the
    844 * static_cast with a promoting binary operation using a guaranteed 32-bit
    845 * (minimum) unsigned value.
    846 */
    847 #define PNG_32b(b,s) (((0xFFFFFFFFU)&(b)) << (s))
    848 #define PNG_U32(b1,b2,b3,b4) \
    849   (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
    850 
    851 /* Chunk name validation.  When using these macros all the arguments should be
    852 * constants, otherwise code bloat may well occur.  The macros are provided
    853 * primarily for use in #if checks.
    854 *
    855 * PNG_32to8 produces a byte value with the right shift; used to extract the
    856 * byte value from a chunk name.
    857 */
    858 #define PNG_32to8(cn,s) (((cn) >> (s)) & 0xffU)
    859 #define PNG_CN_VALID_UPPER(b) ((b) >= 65 && (b) <= 90) /* upper-case ASCII */
    860 #define PNG_CN_VALID_ASCII(b) PNG_CN_VALID_UPPER((b) & ~32U)
    861 #define PNG_CHUNK_NAME_VALID(cn) (\
    862   PNG_CN_VALID_ASCII(PNG_32to8(cn,24)) && /* critical, !ancillary */\
    863   PNG_CN_VALID_ASCII(PNG_32to8(cn,16)) && /* public, !privately defined */\
    864   PNG_CN_VALID_UPPER(PNG_32to8(cn, 8)) && /* VALID, !reserved */\
    865   PNG_CN_VALID_ASCII(PNG_32to8(cn, 0))   /* data-dependent, !copy ok */)
    866 
    867 /* Constants for known chunk types.
    868 *
    869 * MAINTAINERS: If you need to add a chunk, define the name here.
    870 * For historical reasons these constants have the form png_<name>; i.e.
    871 * the prefix is lower case.  Please use decimal values as the parameters to
    872 * match the ISO PNG specification and to avoid relying on the C locale
    873 * interpretation of character values.  Please keep the list sorted.
    874 *
    875 * Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
    876 * type.  In fact the specification does not express chunk types this way,
    877 * however using a 32-bit value means that the chunk type can be read from the
    878 * stream using exactly the same code as used for a 32-bit unsigned value and
    879 * can be examined far more efficiently (using one arithmetic compare).
    880 *
    881 * Prior to 1.5.6 the chunk type constants were expressed as C strings.  The
    882 * libpng API still uses strings for 'unknown' chunks and a macro,
    883 * PNG_STRING_FROM_CHUNK, allows a string to be generated if required.  Notice
    884 * that for portable code numeric values must still be used; the string "IHDR"
    885 * is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
    886 *
    887 * In 1.7.0 the definitions will be made public in png.h to avoid having to
    888 * duplicate the same definitions in application code.
    889 */
    890 #define png_IDAT PNG_U32( 73,  68,  65,  84)
    891 #define png_IEND PNG_U32( 73,  69,  78,  68)
    892 #define png_IHDR PNG_U32( 73,  72,  68,  82)
    893 #define png_PLTE PNG_U32( 80,  76,  84,  69)
    894 #define png_acTL PNG_U32( 97,  99,  84,  76) /* PNGv3: APNG */
    895 #define png_bKGD PNG_U32( 98,  75,  71,  68)
    896 #define png_cHRM PNG_U32( 99,  72,  82,  77)
    897 #define png_cICP PNG_U32( 99,  73,  67,  80) /* PNGv3 */
    898 #define png_cLLI PNG_U32( 99,  76,  76,  73) /* PNGv3 */
    899 #define png_eXIf PNG_U32(101,  88,  73, 102) /* registered July 2017 */
    900 #define png_fcTL PNG_U32(102,  99,  84,  76) /* PNGv3: APNG */
    901 #define png_fdAT PNG_U32(102, 100,  65,  84) /* PNGv3: APNG */
    902 #define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
    903 #define png_gAMA PNG_U32(103,  65,  77,  65)
    904 #define png_gIFg PNG_U32(103,  73,  70, 103)
    905 #define png_gIFt PNG_U32(103,  73,  70, 116) /* deprecated */
    906 #define png_gIFx PNG_U32(103,  73,  70, 120)
    907 #define png_hIST PNG_U32(104,  73,  83,  84)
    908 #define png_iCCP PNG_U32(105,  67,  67,  80)
    909 #define png_iTXt PNG_U32(105,  84,  88, 116)
    910 #define png_mDCV PNG_U32(109,  68,  67,  86) /* PNGv3 */
    911 #define png_oFFs PNG_U32(111,  70,  70, 115)
    912 #define png_pCAL PNG_U32(112,  67,  65,  76)
    913 #define png_pHYs PNG_U32(112,  72,  89, 115)
    914 #define png_sBIT PNG_U32(115,  66,  73,  84)
    915 #define png_sCAL PNG_U32(115,  67,  65,  76)
    916 #define png_sPLT PNG_U32(115,  80,  76,  84)
    917 #define png_sRGB PNG_U32(115,  82,  71,  66)
    918 #define png_sTER PNG_U32(115,  84,  69,  82)
    919 #define png_tEXt PNG_U32(116,  69,  88, 116)
    920 #define png_tIME PNG_U32(116,  73,  77,  69)
    921 #define png_tRNS PNG_U32(116,  82,  78,  83)
    922 #define png_zTXt PNG_U32(122,  84,  88, 116)
    923 
    924 #ifdef PNG_APNG_SUPPORTED
    925 #define png_acTL PNG_U32( 97,  99,  84,  76)
    926 #define png_fcTL PNG_U32(102,  99,  84,  76)
    927 #define png_fdAT PNG_U32(102, 100,  65,  84)
    928 
    929 /* For png_struct.apng_flags: */
    930 #define PNG_FIRST_FRAME_HIDDEN       0x0001U
    931 #define PNG_APNG_APP                 0x0002U
    932 #endif
    933 
    934 /* The following will work on (signed char*) strings, whereas the get_uint_32
    935 * macro will fail on top-bit-set values because of the sign extension.
    936 */
    937 #define PNG_CHUNK_FROM_STRING(s)\
    938   PNG_U32(0xff & (s)[0], 0xff & (s)[1], 0xff & (s)[2], 0xff & (s)[3])
    939 
    940 /* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
    941 * signed and the argument is a (char[])  This macro will fail miserably on
    942 * systems where (char) is more than 8 bits.
    943 */
    944 #define PNG_STRING_FROM_CHUNK(s,c)\
    945   (void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
    946   ((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
    947   ((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
    948   ((char*)(s))[3]=(char)((c & 0xff)))
    949 
    950 /* Do the same but terminate with a null character. */
    951 #define PNG_CSTRING_FROM_CHUNK(s,c)\
    952   (void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
    953 
    954 /* Test on flag values as defined in the spec (section 5.4): */
    955 #define PNG_CHUNK_ANCILLARY(c)   (1 & ((c) >> 29))
    956 #define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLARY(c))
    957 #define PNG_CHUNK_PRIVATE(c)      (1 & ((c) >> 21))
    958 #define PNG_CHUNK_RESERVED(c)     (1 & ((c) >> 13))
    959 #define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >>  5))
    960 
    961 /* Known chunks.  All supported chunks must be listed here.  The macro PNG_CHUNK
    962 * contains the four character ASCII name by which the chunk is identified.  The
    963 * macro is implemented as required to build tables or switch statements which
    964 * require entries for every known chunk.  The macro also contains an index
    965 * value which should be in order (this is checked in png.c).
    966 *
    967 * Notice that "known" does not require "SUPPORTED"; tables should be built in
    968 * such a way that chunks unsupported in a build require no more than the table
    969 * entry (which should be small.)  In particular function pointers for
    970 * unsupported chunks should be NULL.
    971 *
    972 * At present these index values are not exported (not part of the public API)
    973 * so can be changed at will.  For convenience the names are in lexical sort
    974 * order but with the critical chunks at the start in the order of occurence in
    975 * a PNG.
    976 *
    977 * PNG_INFO_ values do not exist for every one of these chunk handles; for
    978 * example PNG_INFO_{IDAT,IEND,tEXt,iTXt,zTXt} and possibly other chunks in the
    979 * future.
    980 */
    981 #define PNG_KNOWN_CHUNKS\
    982   PNG_CHUNK(IHDR,  0)\
    983   PNG_CHUNK(PLTE,  1)\
    984   PNG_CHUNK(IDAT,  2)\
    985   PNG_CHUNK(IEND,  3)\
    986   PNG_CHUNK(acTL,  4)\
    987   PNG_CHUNK(bKGD,  5)\
    988   PNG_CHUNK(cHRM,  6)\
    989   PNG_CHUNK(cICP,  7)\
    990   PNG_CHUNK(cLLI,  8)\
    991   PNG_CHUNK(eXIf,  9)\
    992   PNG_CHUNK(fcTL, 10)\
    993   PNG_CHUNK(fdAT, 11)\
    994   PNG_CHUNK(gAMA, 12)\
    995   PNG_CHUNK(hIST, 13)\
    996   PNG_CHUNK(iCCP, 14)\
    997   PNG_CHUNK(iTXt, 15)\
    998   PNG_CHUNK(mDCV, 16)\
    999   PNG_CHUNK(oFFs, 17)\
   1000   PNG_CHUNK(pCAL, 18)\
   1001   PNG_CHUNK(pHYs, 19)\
   1002   PNG_CHUNK(sBIT, 20)\
   1003   PNG_CHUNK(sCAL, 21)\
   1004   PNG_CHUNK(sPLT, 22)\
   1005   PNG_CHUNK(sRGB, 23)\
   1006   PNG_CHUNK(tEXt, 24)\
   1007   PNG_CHUNK(tIME, 25)\
   1008   PNG_CHUNK(tRNS, 26)\
   1009   PNG_CHUNK(zTXt, 27)
   1010 
   1011 /* Gamma values (new at libpng-1.5.4): */
   1012 #define PNG_GAMMA_MAC_OLD 151724  /* Assume '1.8' is really 2.2/1.45! */
   1013 #define PNG_GAMMA_MAC_INVERSE 65909
   1014 #define PNG_GAMMA_sRGB_INVERSE 45455
   1015 
   1016 /* gamma sanity check.  libpng cannot implement gamma transforms outside a
   1017 * certain limit because of its use of 16-bit fixed point intermediate values.
   1018 * Gamma values that are too large or too small will zap the 16-bit values all
   1019 * to 0 or 65535 resulting in an obvious 'bad' image.
   1020 *
   1021 * In libpng 1.6.0 the limits were changed from 0.07..3 to 0.01..100 to
   1022 * accommodate the optimal 16-bit gamma of 36 and its reciprocal.
   1023 *
   1024 * These are png_fixed_point integral values:
   1025 */
   1026 #define PNG_LIB_GAMMA_MIN 1000
   1027 #define PNG_LIB_GAMMA_MAX 10000000
   1028 
   1029 /* Almost everything below is C specific; the #defines above can be used in
   1030 * non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
   1031 */
   1032 #ifndef PNG_VERSION_INFO_ONLY
   1033 
   1034 #include "pngstruct.h"
   1035 #include "pnginfo.h"
   1036 
   1037 /* Validate the include paths - the include path used to generate pnglibconf.h
   1038 * must match that used in the build, or we must be using pnglibconf.h.prebuilt:
   1039 */
   1040 #if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
   1041 #  error The include path of <zlib.h> is incorrect
   1042   /* When pnglibconf.h was built, the copy of zlib.h that it used was not the
   1043    * same as the one being used here.  Considering how libpng makes decisions
   1044    * to use the zlib API based on the zlib version number, the -I options must
   1045    * match.
   1046    *
   1047    * A possible cause of this mismatch is that you passed an -I option in
   1048    * CFLAGS, which is unlikely to work.  All the preprocessor options, and all
   1049    * the -I options in particular, should be in CPPFLAGS.
   1050    */
   1051 #endif
   1052 
   1053 /* This is used for 16-bit gamma tables -- only the top level pointers are
   1054 * const; this could be changed:
   1055 */
   1056 typedef const png_uint_16p * png_const_uint_16pp;
   1057 
   1058 /* Added to libpng-1.5.7: sRGB conversion tables */
   1059 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   1060   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
   1061 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
   1062 PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
   1063   /* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
   1064    * 0..65535.  This table gives the closest 16-bit answers (no errors).
   1065    */
   1066 #endif
   1067 
   1068 PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
   1069 PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
   1070 
   1071 #define PNG_sRGB_FROM_LINEAR(linear) \
   1072  ((png_byte)(0xff & ((png_sRGB_base[(linear)>>15] \
   1073   + ((((linear) & 0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)))
   1074   /* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
   1075    * encoded value with maximum error 0.646365.  Note that the input is not a
   1076    * 16-bit value; it has been multiplied by 255! */
   1077 #endif /* SIMPLIFIED_READ/WRITE */
   1078 
   1079 
   1080 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
   1081 #ifdef __cplusplus
   1082 extern "C" {
   1083 #endif /* __cplusplus */
   1084 
   1085 /* Internal functions; these are not exported from a DLL however because they
   1086 * are used within several of the C source files they have to be C extern.
   1087 *
   1088 * All of these functions must be declared with PNG_INTERNAL_FUNCTION.
   1089 */
   1090 /* Zlib support */
   1091 #define PNG_UNEXPECTED_ZLIB_RETURN (-7)
   1092 PNG_INTERNAL_FUNCTION(void, png_zstream_error,(png_structrp png_ptr, int ret),
   1093   PNG_EMPTY);
   1094   /* Used by the zlib handling functions to ensure that z_stream::msg is always
   1095    * set before they return.
   1096    */
   1097 
   1098 #ifdef PNG_WRITE_SUPPORTED
   1099 PNG_INTERNAL_FUNCTION(void,png_free_buffer_list,(png_structrp png_ptr,
   1100   png_compression_bufferp *list),PNG_EMPTY);
   1101   /* Free the buffer list used by the compressed write code. */
   1102 #endif
   1103 
   1104 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
   1105   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
   1106   (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
   1107   defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   1108   defined(PNG_mDCV_SUPPORTED) || \
   1109   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
   1110   (defined(PNG_sCAL_SUPPORTED) && \
   1111   defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
   1112 PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
   1113   double fp, png_const_charp text),PNG_EMPTY);
   1114 #endif
   1115 
   1116 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
   1117   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
   1118   (defined(PNG_cLLI_SUPPORTED) || defined(PNG_mDCV_SUPPORTED))
   1119 PNG_INTERNAL_FUNCTION(png_uint_32,png_fixed_ITU,(png_const_structrp png_ptr,
   1120   double fp, png_const_charp text),PNG_EMPTY);
   1121 #endif
   1122 
   1123 /* Check the user version string for compatibility, returns false if the version
   1124 * numbers aren't compatible.
   1125 */
   1126 PNG_INTERNAL_FUNCTION(int,png_user_version_check,(png_structrp png_ptr,
   1127   png_const_charp user_png_ver),PNG_EMPTY);
   1128 
   1129 #ifdef PNG_READ_SUPPORTED /* should only be used on read */
   1130 /* Security: read limits on the largest allocations while reading a PNG.  This
   1131 * avoids very large allocations caused by PNG files with damaged or altered
   1132 * chunk 'length' fields.
   1133 */
   1134 #ifdef PNG_SET_USER_LIMITS_SUPPORTED /* run-time limit */
   1135 #  define png_chunk_max(png_ptr) ((png_ptr)->user_chunk_malloc_max)
   1136 
   1137 #elif PNG_USER_CHUNK_MALLOC_MAX > 0 /* compile-time limit */
   1138 #  define png_chunk_max(png_ptr) ((void)png_ptr, PNG_USER_CHUNK_MALLOC_MAX)
   1139 
   1140 #elif (defined PNG_MAX_MALLOC_64K)  /* legacy system limit */
   1141 #  define png_chunk_max(png_ptr) ((void)png_ptr, 65536U)
   1142 
   1143 #else                               /* modern system limit SIZE_MAX (C99) */
   1144 #  define png_chunk_max(png_ptr) ((void)png_ptr, PNG_SIZE_MAX)
   1145 #endif
   1146 #endif /* READ */
   1147 
   1148 /* Internal base allocator - no messages, NULL on failure to allocate.  This
   1149 * does, however, call the application provided allocator and that could call
   1150 * png_error (although that would be a bug in the application implementation.)
   1151 */
   1152 PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
   1153   png_alloc_size_t size),PNG_ALLOCATED);
   1154 
   1155 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
   1156   defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
   1157 /* Internal array allocator, outputs no error or warning messages on failure,
   1158 * just returns NULL.
   1159 */
   1160 PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
   1161   int nelements, size_t element_size),PNG_ALLOCATED);
   1162 
   1163 /* The same but an existing array is extended by add_elements.  This function
   1164 * also memsets the new elements to 0 and copies the old elements.  The old
   1165 * array is not freed or altered.
   1166 */
   1167 PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_const_structrp png_ptr,
   1168   png_const_voidp array, int old_elements, int add_elements,
   1169   size_t element_size),PNG_ALLOCATED);
   1170 #endif /* text, sPLT or unknown chunks */
   1171 
   1172 /* Magic to create a struct when there is no struct to call the user supplied
   1173 * memory allocators.  Because error handling has not been set up the memory
   1174 * handlers can't safely call png_error, but this is an obscure and undocumented
   1175 * restriction so libpng has to assume that the 'free' handler, at least, might
   1176 * call png_error.
   1177 */
   1178 PNG_INTERNAL_FUNCTION(png_structp,png_create_png_struct,
   1179   (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
   1180    png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
   1181    png_free_ptr free_fn),PNG_ALLOCATED);
   1182 
   1183 /* Free memory from internal libpng struct */
   1184 PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
   1185   PNG_EMPTY);
   1186 
   1187 /* Free an allocated jmp_buf (always succeeds) */
   1188 PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);
   1189 
   1190 /* Function to allocate memory for zlib.  PNGAPI is disallowed. */
   1191 PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
   1192   PNG_ALLOCATED);
   1193 
   1194 /* Function to free memory for zlib.  PNGAPI is disallowed. */
   1195 PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
   1196 
   1197 /* Next four functions are used internally as callbacks.  PNGCBAPI is required
   1198 * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3, changed to
   1199 * PNGCBAPI at 1.5.0
   1200 */
   1201 
   1202 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
   1203    png_bytep data, size_t length),PNG_EMPTY);
   1204 
   1205 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
   1206 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
   1207    png_bytep buffer, size_t length),PNG_EMPTY);
   1208 #endif
   1209 
   1210 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
   1211    png_bytep data, size_t length),PNG_EMPTY);
   1212 
   1213 #ifdef PNG_WRITE_FLUSH_SUPPORTED
   1214 #  ifdef PNG_STDIO_SUPPORTED
   1215 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
   1216   PNG_EMPTY);
   1217 #  endif
   1218 #endif
   1219 
   1220 /* Reset the CRC variable */
   1221 PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);
   1222 
   1223 /* Write the "data" buffer to whatever output you are using */
   1224 PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
   1225    png_const_bytep data, size_t length),PNG_EMPTY);
   1226 
   1227 /* Read and check the PNG file signature */
   1228 PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
   1229   png_inforp info_ptr),PNG_EMPTY);
   1230 
   1231 /* Read the chunk header (length + type name) */
   1232 PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
   1233   PNG_EMPTY);
   1234 
   1235 /* Read data from whatever input you are using into the "data" buffer */
   1236 PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
   1237    size_t length),PNG_EMPTY);
   1238 
   1239 /* Read bytes into buf, and update png_ptr->crc */
   1240 PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
   1241    png_uint_32 length),PNG_EMPTY);
   1242 
   1243 /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
   1244 PNG_INTERNAL_FUNCTION(int,png_crc_finish,(png_structrp png_ptr,
   1245   png_uint_32 skip),PNG_EMPTY);
   1246 
   1247 /* Calculate the CRC over a section of data.  Note that we are only
   1248 * passing a maximum of 64K on systems that have this as a memory limit,
   1249 * since this is the maximum buffer size we can specify.
   1250 */
   1251 PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
   1252   png_const_bytep ptr, size_t length),PNG_EMPTY);
   1253 
   1254 #ifdef PNG_WRITE_FLUSH_SUPPORTED
   1255 PNG_INTERNAL_FUNCTION(void,png_flush,(png_structrp png_ptr),PNG_EMPTY);
   1256 #endif
   1257 
   1258 /* Write various chunks */
   1259 
   1260 /* Write the IHDR chunk, and update the png_struct with the necessary
   1261 * information.
   1262 */
   1263 PNG_INTERNAL_FUNCTION(void,png_write_IHDR,(png_structrp png_ptr,
   1264   png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
   1265   int compression_method, int filter_method, int interlace_method),PNG_EMPTY);
   1266 
   1267 PNG_INTERNAL_FUNCTION(void,png_write_PLTE,(png_structrp png_ptr,
   1268   png_const_colorp palette, png_uint_32 num_pal),PNG_EMPTY);
   1269 
   1270 PNG_INTERNAL_FUNCTION(void,png_compress_IDAT,(png_structrp png_ptr,
   1271   png_const_bytep row_data, png_alloc_size_t row_data_length, int flush),
   1272   PNG_EMPTY);
   1273 
   1274 PNG_INTERNAL_FUNCTION(void,png_write_IEND,(png_structrp png_ptr),PNG_EMPTY);
   1275 
   1276 #ifdef PNG_WRITE_gAMA_SUPPORTED
   1277 PNG_INTERNAL_FUNCTION(void,png_write_gAMA_fixed,(png_structrp png_ptr,
   1278    png_fixed_point file_gamma),PNG_EMPTY);
   1279 #endif
   1280 
   1281 #ifdef PNG_WRITE_sBIT_SUPPORTED
   1282 PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
   1283    png_const_color_8p sbit, int color_type),PNG_EMPTY);
   1284 #endif
   1285 
   1286 #ifdef PNG_WRITE_cHRM_SUPPORTED
   1287 PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
   1288    const png_xy *xy), PNG_EMPTY);
   1289   /* The xy value must have been previously validated */
   1290 #endif
   1291 
   1292 #ifdef PNG_WRITE_cICP_SUPPORTED
   1293 PNG_INTERNAL_FUNCTION(void,png_write_cICP,(png_structrp png_ptr,
   1294    png_byte colour_primaries, png_byte transfer_function,
   1295    png_byte matrix_coefficients, png_byte video_full_range_flag), PNG_EMPTY);
   1296 #endif
   1297 
   1298 #ifdef PNG_WRITE_cLLI_SUPPORTED
   1299 PNG_INTERNAL_FUNCTION(void,png_write_cLLI_fixed,(png_structrp png_ptr,
   1300   png_uint_32 maxCLL, png_uint_32 maxFALL), PNG_EMPTY);
   1301 #endif
   1302 
   1303 #ifdef PNG_WRITE_mDCV_SUPPORTED
   1304 PNG_INTERNAL_FUNCTION(void,png_write_mDCV_fixed,(png_structrp png_ptr,
   1305   png_uint_16 red_x, png_uint_16 red_y,
   1306   png_uint_16 green_x, png_uint_16 green_y,
   1307   png_uint_16 blue_x, png_uint_16 blue_y,
   1308   png_uint_16 white_x, png_uint_16 white_y,
   1309   png_uint_32 maxDL, png_uint_32 minDL), PNG_EMPTY);
   1310 #endif
   1311 
   1312 #ifdef PNG_WRITE_sRGB_SUPPORTED
   1313 PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
   1314    int intent),PNG_EMPTY);
   1315 #endif
   1316 
   1317 #ifdef PNG_WRITE_eXIf_SUPPORTED
   1318 PNG_INTERNAL_FUNCTION(void,png_write_eXIf,(png_structrp png_ptr,
   1319    png_bytep exif, int num_exif),PNG_EMPTY);
   1320 #endif
   1321 
   1322 #ifdef PNG_WRITE_iCCP_SUPPORTED
   1323 PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
   1324   png_const_charp name, png_const_bytep profile, png_uint_32 proflen),
   1325   PNG_EMPTY);
   1326   /* Writes a previously 'set' profile.  The profile argument is **not**
   1327    * compressed.
   1328    */
   1329 #endif
   1330 
   1331 #ifdef PNG_WRITE_sPLT_SUPPORTED
   1332 PNG_INTERNAL_FUNCTION(void,png_write_sPLT,(png_structrp png_ptr,
   1333    png_const_sPLT_tp palette),PNG_EMPTY);
   1334 #endif
   1335 
   1336 #ifdef PNG_WRITE_tRNS_SUPPORTED
   1337 PNG_INTERNAL_FUNCTION(void,png_write_tRNS,(png_structrp png_ptr,
   1338    png_const_bytep trans, png_const_color_16p values, int number,
   1339    int color_type),PNG_EMPTY);
   1340 #endif
   1341 
   1342 #ifdef PNG_WRITE_bKGD_SUPPORTED
   1343 PNG_INTERNAL_FUNCTION(void,png_write_bKGD,(png_structrp png_ptr,
   1344    png_const_color_16p values, int color_type),PNG_EMPTY);
   1345 #endif
   1346 
   1347 #ifdef PNG_WRITE_hIST_SUPPORTED
   1348 PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
   1349    png_const_uint_16p hist, int num_hist),PNG_EMPTY);
   1350 #endif
   1351 
   1352 /* Chunks that have keywords */
   1353 #ifdef PNG_WRITE_tEXt_SUPPORTED
   1354 PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
   1355   png_const_charp key, png_const_charp text, size_t text_len),PNG_EMPTY);
   1356 #endif
   1357 
   1358 #ifdef PNG_WRITE_zTXt_SUPPORTED
   1359 PNG_INTERNAL_FUNCTION(void,png_write_zTXt,(png_structrp png_ptr, png_const_charp
   1360    key, png_const_charp text, int compression),PNG_EMPTY);
   1361 #endif
   1362 
   1363 #ifdef PNG_WRITE_iTXt_SUPPORTED
   1364 PNG_INTERNAL_FUNCTION(void,png_write_iTXt,(png_structrp png_ptr,
   1365    int compression, png_const_charp key, png_const_charp lang,
   1366    png_const_charp lang_key, png_const_charp text),PNG_EMPTY);
   1367 #endif
   1368 
   1369 #ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
   1370 PNG_INTERNAL_FUNCTION(int,png_set_text_2,(png_const_structrp png_ptr,
   1371    png_inforp info_ptr, png_const_textp text_ptr, int num_text),PNG_EMPTY);
   1372 #endif
   1373 
   1374 #ifdef PNG_WRITE_oFFs_SUPPORTED
   1375 PNG_INTERNAL_FUNCTION(void,png_write_oFFs,(png_structrp png_ptr,
   1376    png_int_32 x_offset, png_int_32 y_offset, int unit_type),PNG_EMPTY);
   1377 #endif
   1378 
   1379 #ifdef PNG_WRITE_pCAL_SUPPORTED
   1380 PNG_INTERNAL_FUNCTION(void,png_write_pCAL,(png_structrp png_ptr,
   1381    png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
   1382    png_const_charp units, png_charpp params),PNG_EMPTY);
   1383 #endif
   1384 
   1385 #ifdef PNG_WRITE_pHYs_SUPPORTED
   1386 PNG_INTERNAL_FUNCTION(void,png_write_pHYs,(png_structrp png_ptr,
   1387    png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
   1388    int unit_type),PNG_EMPTY);
   1389 #endif
   1390 
   1391 #ifdef PNG_WRITE_tIME_SUPPORTED
   1392 PNG_INTERNAL_FUNCTION(void,png_write_tIME,(png_structrp png_ptr,
   1393    png_const_timep mod_time),PNG_EMPTY);
   1394 #endif
   1395 
   1396 #ifdef PNG_WRITE_sCAL_SUPPORTED
   1397 PNG_INTERNAL_FUNCTION(void,png_write_sCAL_s,(png_structrp png_ptr,
   1398    int unit, png_const_charp width, png_const_charp height),PNG_EMPTY);
   1399 #endif
   1400 
   1401 /* Called when finished processing a row of data */
   1402 PNG_INTERNAL_FUNCTION(void,png_write_finish_row,(png_structrp png_ptr),
   1403    PNG_EMPTY);
   1404 
   1405 /* Internal use only.   Called before first row of data */
   1406 PNG_INTERNAL_FUNCTION(void,png_write_start_row,(png_structrp png_ptr),
   1407    PNG_EMPTY);
   1408 
   1409 /* Combine a row of data, dealing with alpha, etc. if requested.  'row' is an
   1410 * array of png_ptr->width pixels.  If the image is not interlaced or this
   1411 * is the final pass this just does a memcpy, otherwise the "display" flag
   1412 * is used to determine whether to copy pixels that are not in the current pass.
   1413 *
   1414 * Because 'png_do_read_interlace' (below) replicates pixels this allows this
   1415 * function to achieve the documented 'blocky' appearance during interlaced read
   1416 * if display is 1 and the 'sparkle' appearance, where existing pixels in 'row'
   1417 * are not changed if they are not in the current pass, when display is 0.
   1418 *
   1419 * 'display' must be 0 or 1, otherwise the memcpy will be done regardless.
   1420 *
   1421 * The API always reads from the png_struct row buffer and always assumes that
   1422 * it is full width (png_do_read_interlace has already been called.)
   1423 *
   1424 * This function is only ever used to write to row buffers provided by the
   1425 * caller of the relevant libpng API and the row must have already been
   1426 * transformed by the read transformations.
   1427 *
   1428 * The PNG_USE_COMPILE_TIME_MASKS option causes generation of pre-computed
   1429 * bitmasks for use within the code, otherwise runtime generated masks are used.
   1430 * The default is compile time masks.
   1431 */
   1432 #ifndef PNG_USE_COMPILE_TIME_MASKS
   1433 #  define PNG_USE_COMPILE_TIME_MASKS 1
   1434 #endif
   1435 PNG_INTERNAL_FUNCTION(void,png_combine_row,(png_const_structrp png_ptr,
   1436    png_bytep row, int display),PNG_EMPTY);
   1437 
   1438 #ifdef PNG_READ_INTERLACING_SUPPORTED
   1439 /* Expand an interlaced row: the 'row_info' describes the pass data that has
   1440 * been read in and must correspond to the pixels in 'row', the pixels are
   1441 * expanded (moved apart) in 'row' to match the final layout, when doing this
   1442 * the pixels are *replicated* to the intervening space.  This is essential for
   1443 * the correct operation of png_combine_row, above.
   1444 */
   1445 PNG_INTERNAL_FUNCTION(void,png_do_read_interlace,(png_row_infop row_info,
   1446    png_bytep row, int pass, png_uint_32 transformations),PNG_EMPTY);
   1447 #endif
   1448 
   1449 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
   1450 
   1451 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   1452 /* Grab pixels out of a row for an interlaced pass */
   1453 PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
   1454    png_bytep row, int pass),PNG_EMPTY);
   1455 #endif
   1456 
   1457 /* Unfilter a row: check the filter value before calling this, there is no point
   1458 * calling it for PNG_FILTER_VALUE_NONE.
   1459 */
   1460 PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
   1461    row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);
   1462 
   1463 #if PNG_ARM_NEON_OPT > 0
   1464 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
   1465    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1466 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
   1467    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1468 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_neon,(png_row_infop
   1469    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1470 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_neon,(png_row_infop
   1471    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1472 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_neon,(png_row_infop
   1473    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1474 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
   1475    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1476 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
   1477    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1478 #endif
   1479 
   1480 #if PNG_MIPS_MSA_IMPLEMENTATION == 1
   1481 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_msa,(png_row_infop row_info,
   1482    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1483 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_msa,(png_row_infop
   1484    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1485 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_msa,(png_row_infop
   1486    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1487 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_msa,(png_row_infop
   1488    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1489 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
   1490    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1491 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
   1492    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1493 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
   1494    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1495 #endif
   1496 
   1497 #if PNG_MIPS_MMI_IMPLEMENTATION > 0
   1498 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_mmi,(png_row_infop row_info,
   1499    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1500 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_mmi,(png_row_infop
   1501    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1502 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_mmi,(png_row_infop
   1503    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1504 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_mmi,(png_row_infop
   1505    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1506 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_mmi,(png_row_infop
   1507    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1508 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_mmi,(png_row_infop
   1509    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1510 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_mmi,(png_row_infop
   1511    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1512 #endif
   1513 
   1514 #if PNG_POWERPC_VSX_OPT > 0
   1515 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_vsx,(png_row_infop row_info,
   1516    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1517 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_vsx,(png_row_infop
   1518    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1519 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_vsx,(png_row_infop
   1520    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1521 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_vsx,(png_row_infop
   1522    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1523 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_vsx,(png_row_infop
   1524    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1525 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_vsx,(png_row_infop
   1526    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1527 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_vsx,(png_row_infop
   1528    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1529 #endif
   1530 
   1531 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
   1532 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
   1533    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1534 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
   1535    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1536 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
   1537    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1538 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
   1539    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1540 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
   1541    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1542 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
   1543    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1544 #endif
   1545 
   1546 #if PNG_LOONGARCH_LSX_IMPLEMENTATION == 1
   1547 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_lsx,(png_row_infop
   1548    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1549 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_lsx,(png_row_infop
   1550    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1551 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_lsx,(png_row_infop
   1552    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1553 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_lsx,(png_row_infop
   1554    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1555 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_lsx,(png_row_infop
   1556    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1557 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_lsx,(png_row_infop
   1558    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1559 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_lsx,(png_row_infop
   1560    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1561 #endif
   1562 
   1563 #if PNG_RISCV_RVV_IMPLEMENTATION == 1
   1564 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_rvv,(png_row_infop
   1565    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1566 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_rvv,(png_row_infop
   1567    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1568 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_rvv,(png_row_infop
   1569    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1570 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_rvv,(png_row_infop
   1571    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1572 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_rvv,(png_row_infop
   1573    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1574 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_rvv,(png_row_infop
   1575    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1576 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_rvv,(png_row_infop
   1577    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
   1578 #endif
   1579 
   1580 /* Choose the best filter to use and filter the row data */
   1581 PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
   1582    png_row_infop row_info),PNG_EMPTY);
   1583 
   1584 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
   1585 PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
   1586   png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
   1587   /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
   1588    * is NULL the function checks, instead, for the end of the stream.  In this
   1589    * case a benign error will be issued if the stream end is not found or if
   1590    * extra data has to be consumed.
   1591    */
   1592 PNG_INTERNAL_FUNCTION(void,png_read_finish_IDAT,(png_structrp png_ptr),
   1593   PNG_EMPTY);
   1594   /* This cleans up when the IDAT LZ stream does not end when the last image
   1595    * byte is read; there is still some pending input.
   1596    */
   1597 
   1598 PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
   1599   PNG_EMPTY);
   1600   /* Finish a row while reading, dealing with interlacing passes, etc. */
   1601 #endif /* SEQUENTIAL_READ */
   1602 
   1603 /* Initialize the row buffers, etc. */
   1604 PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);
   1605 
   1606 #if ZLIB_VERNUM >= 0x1240
   1607 PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
   1608      PNG_EMPTY);
   1609 #  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
   1610 #else /* Zlib < 1.2.4 */
   1611 #  define PNG_INFLATE(pp, flush) inflate(&(pp)->zstream, flush)
   1612 #endif /* Zlib < 1.2.4 */
   1613 
   1614 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1615 /* Optional call to update the users info structure */
   1616 PNG_INTERNAL_FUNCTION(void,png_read_transform_info,(png_structrp png_ptr,
   1617    png_inforp info_ptr),PNG_EMPTY);
   1618 #endif
   1619 
   1620 /* Shared transform functions, defined in pngtran.c */
   1621 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
   1622    defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
   1623 PNG_INTERNAL_FUNCTION(void,png_do_strip_channel,(png_row_infop row_info,
   1624    png_bytep row, int at_start),PNG_EMPTY);
   1625 #endif
   1626 
   1627 #ifdef PNG_16BIT_SUPPORTED
   1628 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
   1629 PNG_INTERNAL_FUNCTION(void,png_do_swap,(png_row_infop row_info,
   1630    png_bytep row),PNG_EMPTY);
   1631 #endif
   1632 #endif
   1633 
   1634 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
   1635    defined(PNG_WRITE_PACKSWAP_SUPPORTED)
   1636 PNG_INTERNAL_FUNCTION(void,png_do_packswap,(png_row_infop row_info,
   1637    png_bytep row),PNG_EMPTY);
   1638 #endif
   1639 
   1640 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
   1641 PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_row_infop row_info,
   1642    png_bytep row),PNG_EMPTY);
   1643 #endif
   1644 
   1645 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
   1646 PNG_INTERNAL_FUNCTION(void,png_do_bgr,(png_row_infop row_info,
   1647    png_bytep row),PNG_EMPTY);
   1648 #endif
   1649 
   1650 /* The following decodes the appropriate chunks, and does error correction,
   1651 * then calls the appropriate callback for the chunk if it is valid.
   1652 */
   1653 typedef enum
   1654 {
   1655   /* Result of a call to png_handle_chunk made to handle the current chunk
   1656    * png_struct::chunk_name on read.  Always informational, either the stream
   1657    * is read for the next chunk or the routine will call png_error.
   1658    *
   1659    * NOTE: order is important internally.  handled_saved and above are regarded
   1660    * as handling the chunk.
   1661    */
   1662   handled_error = 0,  /* bad crc or known and bad format or too long */
   1663   handled_discarded,  /* not saved in the unknown chunk list */
   1664   handled_saved,      /* saved in the unknown chunk list */
   1665   handled_ok          /* known, supported and handled without error */
   1666 } png_handle_result_code;
   1667 
   1668 PNG_INTERNAL_FUNCTION(png_handle_result_code,png_handle_unknown,
   1669    (png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length, int keep),
   1670    PNG_EMPTY);
   1671   /* This is the function that gets called for unknown chunks.  The 'keep'
   1672    * argument is either non-zero for a known chunk that has been set to be
   1673    * handled as unknown or zero for an unknown chunk.  By default the function
   1674    * just skips the chunk or errors out if it is critical.
   1675    */
   1676 
   1677 PNG_INTERNAL_FUNCTION(png_handle_result_code,png_handle_chunk,
   1678    (png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
   1679   /* This handles the current chunk png_ptr->chunk_name with unread
   1680    * data[length] and returns one of the above result codes.
   1681    */
   1682 
   1683 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
   1684    defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
   1685 PNG_INTERNAL_FUNCTION(int,png_chunk_unknown_handling,
   1686    (png_const_structrp png_ptr, png_uint_32 chunk_name),PNG_EMPTY);
   1687   /* Exactly as the API png_handle_as_unknown() except that the argument is a
   1688    * 32-bit chunk name, not a string.
   1689    */
   1690 #endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
   1691 
   1692 /* Handle the transformations for reading and writing */
   1693 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1694 PNG_INTERNAL_FUNCTION(void,png_do_read_transformations,(png_structrp png_ptr,
   1695   png_row_infop row_info),PNG_EMPTY);
   1696 #endif
   1697 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
   1698 PNG_INTERNAL_FUNCTION(void,png_do_write_transformations,(png_structrp png_ptr,
   1699   png_row_infop row_info),PNG_EMPTY);
   1700 #endif
   1701 
   1702 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   1703 PNG_INTERNAL_FUNCTION(void,png_init_read_transformations,(png_structrp png_ptr),
   1704    PNG_EMPTY);
   1705 #endif
   1706 
   1707 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
   1708 PNG_INTERNAL_FUNCTION(void,png_push_read_chunk,(png_structrp png_ptr,
   1709    png_inforp info_ptr),PNG_EMPTY);
   1710 PNG_INTERNAL_FUNCTION(void,png_push_read_sig,(png_structrp png_ptr,
   1711    png_inforp info_ptr),PNG_EMPTY);
   1712 PNG_INTERNAL_FUNCTION(void,png_push_check_crc,(png_structrp png_ptr),PNG_EMPTY);
   1713 PNG_INTERNAL_FUNCTION(void,png_push_save_buffer,(png_structrp png_ptr),
   1714    PNG_EMPTY);
   1715 PNG_INTERNAL_FUNCTION(void,png_push_restore_buffer,(png_structrp png_ptr,
   1716    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
   1717 PNG_INTERNAL_FUNCTION(void,png_push_read_IDAT,(png_structrp png_ptr),PNG_EMPTY);
   1718 PNG_INTERNAL_FUNCTION(void,png_process_IDAT_data,(png_structrp png_ptr,
   1719    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
   1720 PNG_INTERNAL_FUNCTION(void,png_push_process_row,(png_structrp png_ptr),
   1721    PNG_EMPTY);
   1722 PNG_INTERNAL_FUNCTION(void,png_push_have_info,(png_structrp png_ptr,
   1723   png_inforp info_ptr),PNG_EMPTY);
   1724 PNG_INTERNAL_FUNCTION(void,png_push_have_end,(png_structrp png_ptr,
   1725   png_inforp info_ptr),PNG_EMPTY);
   1726 PNG_INTERNAL_FUNCTION(void,png_push_have_row,(png_structrp png_ptr,
   1727    png_bytep row),PNG_EMPTY);
   1728 PNG_INTERNAL_FUNCTION(void,png_push_read_end,(png_structrp png_ptr,
   1729    png_inforp info_ptr),PNG_EMPTY);
   1730 PNG_INTERNAL_FUNCTION(void,png_process_some_data,(png_structrp png_ptr,
   1731    png_inforp info_ptr),PNG_EMPTY);
   1732 PNG_INTERNAL_FUNCTION(void,png_read_push_finish_row,(png_structrp png_ptr),
   1733    PNG_EMPTY);
   1734 #endif /* PROGRESSIVE_READ */
   1735 
   1736 #ifdef PNG_APNG_SUPPORTED
   1737 PNG_INTERNAL_FUNCTION(void,png_ensure_fcTL_is_valid,(png_structp png_ptr,
   1738   png_uint_32 width, png_uint_32 height,
   1739   png_uint_32 x_offset, png_uint_32 y_offset,
   1740   png_uint_16 delay_num, png_uint_16 delay_den,
   1741   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
   1742 
   1743 #ifdef PNG_READ_APNG_SUPPORTED
   1744 PNG_INTERNAL_FUNCTION(void,png_handle_acTL,(png_structp png_ptr,
   1745   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
   1746 PNG_INTERNAL_FUNCTION(void,png_handle_fcTL,(png_structp png_ptr,
   1747   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
   1748 PNG_INTERNAL_FUNCTION(void,png_handle_fdAT,(png_structp png_ptr,
   1749   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
   1750 PNG_INTERNAL_FUNCTION(void,png_have_info,(png_structp png_ptr,
   1751   png_infop info_ptr),PNG_EMPTY);
   1752 PNG_INTERNAL_FUNCTION(void,png_ensure_sequence_number,(png_structp png_ptr,
   1753   png_uint_32 length),PNG_EMPTY);
   1754 PNG_INTERNAL_FUNCTION(void,png_read_reset,(png_structp png_ptr),PNG_EMPTY);
   1755 PNG_INTERNAL_FUNCTION(void,png_read_reinit,(png_structp png_ptr,
   1756   png_infop info_ptr),PNG_EMPTY);
   1757 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
   1758 PNG_INTERNAL_FUNCTION(void,png_progressive_read_reset,(png_structp png_ptr),
   1759   PNG_EMPTY);
   1760 #endif /* PROGRESSIVE_READ */
   1761 #endif /* READ_APNG */
   1762 
   1763 #ifdef PNG_WRITE_APNG_SUPPORTED
   1764 PNG_INTERNAL_FUNCTION(void,png_write_acTL,(png_structp png_ptr,
   1765   png_uint_32 num_frames, png_uint_32 num_plays),PNG_EMPTY);
   1766 PNG_INTERNAL_FUNCTION(void,png_write_fcTL,(png_structp png_ptr,
   1767   png_uint_32 width, png_uint_32 height,
   1768   png_uint_32 x_offset, png_uint_32 y_offset,
   1769   png_uint_16 delay_num, png_uint_16 delay_den,
   1770   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
   1771 PNG_INTERNAL_FUNCTION(void,png_write_fdAT,(png_structp png_ptr,
   1772   png_const_bytep data, png_size_t length),PNG_EMPTY);
   1773 PNG_INTERNAL_FUNCTION(void,png_write_reset,(png_structp png_ptr),PNG_EMPTY);
   1774 PNG_INTERNAL_FUNCTION(void,png_write_reinit,(png_structp png_ptr,
   1775   png_infop info_ptr, png_uint_32 width, png_uint_32 height),PNG_EMPTY);
   1776 #endif /* WRITE_APNG */
   1777 #endif /* APNG */
   1778 
   1779 #ifdef PNG_iCCP_SUPPORTED
   1780 /* Routines for checking parts of an ICC profile. */
   1781 #ifdef PNG_READ_iCCP_SUPPORTED
   1782 PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
   1783   png_const_charp name, png_uint_32 profile_length), PNG_EMPTY);
   1784 #endif /* READ_iCCP */
   1785 PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
   1786   png_const_charp name, png_uint_32 profile_length,
   1787   png_const_bytep profile /* first 132 bytes only */, int color_type),
   1788   PNG_EMPTY);
   1789 PNG_INTERNAL_FUNCTION(int,png_icc_check_tag_table,(png_const_structrp png_ptr,
   1790   png_const_charp name, png_uint_32 profile_length,
   1791   png_const_bytep profile /* header plus whole tag table */), PNG_EMPTY);
   1792 #endif /* iCCP */
   1793 
   1794 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
   1795 PNG_INTERNAL_FUNCTION(void,png_set_rgb_coefficients, (png_structrp png_ptr),
   1796   PNG_EMPTY);
   1797   /* Set the rgb_to_gray coefficients from the cHRM Y values (if unset) */
   1798 #endif /* READ_RGB_TO_GRAY */
   1799 
   1800 /* Added at libpng version 1.4.0 */
   1801 PNG_INTERNAL_FUNCTION(void,png_check_IHDR,(png_const_structrp png_ptr,
   1802    png_uint_32 width, png_uint_32 height, int bit_depth,
   1803    int color_type, int interlace_type, int compression_type,
   1804    int filter_type),PNG_EMPTY);
   1805 
   1806 /* Added at libpng version 1.5.10 */
   1807 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
   1808    defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
   1809 PNG_INTERNAL_FUNCTION(void,png_do_check_palette_indexes,
   1810   (png_structrp png_ptr, png_row_infop row_info),PNG_EMPTY);
   1811 #endif
   1812 
   1813 #if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
   1814 PNG_INTERNAL_FUNCTION(void,png_fixed_error,(png_const_structrp png_ptr,
   1815   png_const_charp name),PNG_NORETURN);
   1816 #endif
   1817 
   1818 /* Puts 'string' into 'buffer' at buffer[pos], taking care never to overwrite
   1819 * the end.  Always leaves the buffer nul terminated.  Never errors out (and
   1820 * there is no error code.)
   1821 */
   1822 PNG_INTERNAL_FUNCTION(size_t,png_safecat,(png_charp buffer, size_t bufsize,
   1823   size_t pos, png_const_charp string),PNG_EMPTY);
   1824 
   1825 /* Various internal functions to handle formatted warning messages, currently
   1826 * only implemented for warnings.
   1827 */
   1828 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
   1829 /* Utility to dump an unsigned value into a buffer, given a start pointer and
   1830 * and end pointer (which should point just *beyond* the end of the buffer!)
   1831 * Returns the pointer to the start of the formatted string.  This utility only
   1832 * does unsigned values.
   1833 */
   1834 PNG_INTERNAL_FUNCTION(png_charp,png_format_number,(png_const_charp start,
   1835   png_charp end, int format, png_alloc_size_t number),PNG_EMPTY);
   1836 
   1837 /* Convenience macro that takes an array: */
   1838 #define PNG_FORMAT_NUMBER(buffer,format,number) \
   1839   png_format_number(buffer, buffer + (sizeof buffer), format, number)
   1840 
   1841 /* Suggested size for a number buffer (enough for 64 bits and a sign!) */
   1842 #define PNG_NUMBER_BUFFER_SIZE 24
   1843 
   1844 /* These are the integer formats currently supported, the name is formed from
   1845 * the standard printf(3) format string.
   1846 */
   1847 #define PNG_NUMBER_FORMAT_u     1 /* chose unsigned API! */
   1848 #define PNG_NUMBER_FORMAT_02u   2
   1849 #define PNG_NUMBER_FORMAT_d     1 /* chose signed API! */
   1850 #define PNG_NUMBER_FORMAT_02d   2
   1851 #define PNG_NUMBER_FORMAT_x     3
   1852 #define PNG_NUMBER_FORMAT_02x   4
   1853 #define PNG_NUMBER_FORMAT_fixed 5 /* choose the signed API */
   1854 #endif
   1855 
   1856 #ifdef PNG_WARNINGS_SUPPORTED
   1857 /* New defines and members adding in libpng-1.5.4 */
   1858 #  define PNG_WARNING_PARAMETER_SIZE 32
   1859 #  define PNG_WARNING_PARAMETER_COUNT 8 /* Maximum 9; see pngerror.c */
   1860 
   1861 /* An l-value of this type has to be passed to the APIs below to cache the
   1862 * values of the parameters to a formatted warning message.
   1863 */
   1864 typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
   1865   PNG_WARNING_PARAMETER_SIZE];
   1866 
   1867 PNG_INTERNAL_FUNCTION(void,png_warning_parameter,(png_warning_parameters p,
   1868   int number, png_const_charp string),PNG_EMPTY);
   1869   /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
   1870    * including the trailing '\0'.
   1871    */
   1872 PNG_INTERNAL_FUNCTION(void,png_warning_parameter_unsigned,
   1873   (png_warning_parameters p, int number, int format, png_alloc_size_t value),
   1874   PNG_EMPTY);
   1875   /* Use png_alloc_size_t because it is an unsigned type as big as any we
   1876    * need to output.  Use the following for a signed value.
   1877    */
   1878 PNG_INTERNAL_FUNCTION(void,png_warning_parameter_signed,
   1879   (png_warning_parameters p, int number, int format, png_int_32 value),
   1880   PNG_EMPTY);
   1881 
   1882 PNG_INTERNAL_FUNCTION(void,png_formatted_warning,(png_const_structrp png_ptr,
   1883   png_warning_parameters p, png_const_charp message),PNG_EMPTY);
   1884   /* 'message' follows the X/Open approach of using @1, @2 to insert
   1885    * parameters previously supplied using the above functions.  Errors in
   1886    * specifying the parameters will simply result in garbage substitutions.
   1887    */
   1888 #endif
   1889 
   1890 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
   1891 /* Application errors (new in 1.6); use these functions (declared below) for
   1892 * errors in the parameters or order of API function calls on read.  The
   1893 * 'warning' should be used for an error that can be handled completely; the
   1894 * 'error' for one which can be handled safely but which may lose application
   1895 * information or settings.
   1896 *
   1897 * By default these both result in a png_error call prior to release, while in a
   1898 * released version the 'warning' is just a warning.  However if the application
   1899 * explicitly disables benign errors (explicitly permitting the code to lose
   1900 * information) they both turn into warnings.
   1901 *
   1902 * If benign errors aren't supported they end up as the corresponding base call
   1903 * (png_warning or png_error.)
   1904 */
   1905 PNG_INTERNAL_FUNCTION(void,png_app_warning,(png_const_structrp png_ptr,
   1906   png_const_charp message),PNG_EMPTY);
   1907   /* The application provided invalid parameters to an API function or called
   1908    * an API function at the wrong time, libpng can completely recover.
   1909    */
   1910 
   1911 PNG_INTERNAL_FUNCTION(void,png_app_error,(png_const_structrp png_ptr,
   1912   png_const_charp message),PNG_EMPTY);
   1913   /* As above but libpng will ignore the call, or attempt some other partial
   1914    * recovery from the error.
   1915    */
   1916 #else
   1917 #  define png_app_warning(pp,s) png_warning(pp,s)
   1918 #  define png_app_error(pp,s) png_error(pp,s)
   1919 #endif
   1920 
   1921 PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
   1922   png_const_charp message, int error),PNG_EMPTY);
   1923   /* Report a recoverable issue in chunk data.  On read this is used to report
   1924    * a problem found while reading a particular chunk and the
   1925    * png_chunk_benign_error or png_chunk_warning function is used as
   1926    * appropriate.  On write this is used to report an error that comes from
   1927    * data set via an application call to a png_set_ API and png_app_error or
   1928    * png_app_warning is used as appropriate.
   1929    *
   1930    * The 'error' parameter must have one of the following values:
   1931    */
   1932 #define PNG_CHUNK_WARNING     0 /* never an error */
   1933 #define PNG_CHUNK_WRITE_ERROR 1 /* an error only on write */
   1934 #define PNG_CHUNK_ERROR       2 /* always an error */
   1935 
   1936 /* ASCII to FP interfaces, currently only implemented if sCAL
   1937 * support is required.
   1938 */
   1939 #if defined(PNG_sCAL_SUPPORTED)
   1940 /* MAX_DIGITS is actually the maximum number of characters in an sCAL
   1941 * width or height, derived from the precision (number of significant
   1942 * digits - a build time settable option) and assumptions about the
   1943 * maximum ridiculous exponent.
   1944 */
   1945 #define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
   1946 
   1947 #ifdef PNG_FLOATING_POINT_SUPPORTED
   1948 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
   1949   png_charp ascii, size_t size, double fp, unsigned int precision),
   1950   PNG_EMPTY);
   1951 #endif /* FLOATING_POINT */
   1952 
   1953 #ifdef PNG_FIXED_POINT_SUPPORTED
   1954 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
   1955   png_charp ascii, size_t size, png_fixed_point fp),PNG_EMPTY);
   1956 #endif /* FIXED_POINT */
   1957 #endif /* sCAL */
   1958 
   1959 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
   1960 /* An internal API to validate the format of a floating point number.
   1961 * The result is the index of the next character.  If the number is
   1962 * not valid it will be the index of a character in the supposed number.
   1963 *
   1964 * The format of a number is defined in the PNG extensions specification
   1965 * and this API is strictly conformant to that spec, not anyone elses!
   1966 *
   1967 * The format as a regular expression is:
   1968 *
   1969 * [+-]?[0-9]+.?([Ee][+-]?[0-9]+)?
   1970 *
   1971 * or:
   1972 *
   1973 * [+-]?.[0-9]+(.[0-9]+)?([Ee][+-]?[0-9]+)?
   1974 *
   1975 * The complexity is that either integer or fraction must be present and the
   1976 * fraction is permitted to have no digits only if the integer is present.
   1977 *
   1978 * NOTE: The dangling E problem.
   1979 *   There is a PNG valid floating point number in the following:
   1980 *
   1981 *       PNG floating point numbers are not greedy.
   1982 *
   1983 *   Working this out requires *TWO* character lookahead (because of the
   1984 *   sign), the parser does not do this - it will fail at the 'r' - this
   1985 *   doesn't matter for PNG sCAL chunk values, but it requires more care
   1986 *   if the value were ever to be embedded in something more complex.  Use
   1987 *   ANSI-C strtod if you need the lookahead.
   1988 */
   1989 /* State table for the parser. */
   1990 #define PNG_FP_INTEGER    0  /* before or in integer */
   1991 #define PNG_FP_FRACTION   1  /* before or in fraction */
   1992 #define PNG_FP_EXPONENT   2  /* before or in exponent */
   1993 #define PNG_FP_STATE      3  /* mask for the above */
   1994 #define PNG_FP_SAW_SIGN   4  /* Saw +/- in current state */
   1995 #define PNG_FP_SAW_DIGIT  8  /* Saw a digit in current state */
   1996 #define PNG_FP_SAW_DOT   16  /* Saw a dot in current state */
   1997 #define PNG_FP_SAW_E     32  /* Saw an E (or e) in current state */
   1998 #define PNG_FP_SAW_ANY   60  /* Saw any of the above 4 */
   1999 
   2000 /* These three values don't affect the parser.  They are set but not used.
   2001 */
   2002 #define PNG_FP_WAS_VALID 64  /* Preceding substring is a valid fp number */
   2003 #define PNG_FP_NEGATIVE 128  /* A negative number, including "-0" */
   2004 #define PNG_FP_NONZERO  256  /* A non-zero value */
   2005 #define PNG_FP_STICKY   448  /* The above three flags */
   2006 
   2007 /* This is available for the caller to store in 'state' if required.  Do not
   2008 * call the parser after setting it (the parser sometimes clears it.)
   2009 */
   2010 #define PNG_FP_INVALID  512  /* Available for callers as a distinct value */
   2011 
   2012 /* Result codes for the parser (boolean - true means ok, false means
   2013 * not ok yet.)
   2014 */
   2015 #define PNG_FP_MAYBE      0  /* The number may be valid in the future */
   2016 #define PNG_FP_OK         1  /* The number is valid */
   2017 
   2018 /* Tests on the sticky non-zero and negative flags.  To pass these checks
   2019 * the state must also indicate that the whole number is valid - this is
   2020 * achieved by testing PNG_FP_SAW_DIGIT (see the implementation for why this
   2021 * is equivalent to PNG_FP_OK above.)
   2022 */
   2023 #define PNG_FP_NZ_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NEGATIVE | PNG_FP_NONZERO)
   2024   /* NZ_MASK: the string is valid and a non-zero negative value */
   2025 #define PNG_FP_Z_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NONZERO)
   2026   /* Z MASK: the string is valid and a non-zero value. */
   2027   /* PNG_FP_SAW_DIGIT: the string is valid. */
   2028 #define PNG_FP_IS_ZERO(state) (((state) & PNG_FP_Z_MASK) == PNG_FP_SAW_DIGIT)
   2029 #define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
   2030 #define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)
   2031 
   2032 /* The actual parser.  This can be called repeatedly. It updates
   2033 * the index into the string and the state variable (which must
   2034 * be initialized to 0).  It returns a result code, as above.  There
   2035 * is no point calling the parser any more if it fails to advance to
   2036 * the end of the string - it is stuck on an invalid character (or
   2037 * terminated by '\0').
   2038 *
   2039 * Note that the pointer will consume an E or even an E+ and then leave
   2040 * a 'maybe' state even though a preceding integer.fraction is valid.
   2041 * The PNG_FP_WAS_VALID flag indicates that a preceding substring was
   2042 * a valid number.  It's possible to recover from this by calling
   2043 * the parser again (from the start, with state 0) but with a string
   2044 * that omits the last character (i.e. set the size to the index of
   2045 * the problem character.)  This has not been tested within libpng.
   2046 */
   2047 PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
   2048   size_t size, int *statep, size_t *whereami),PNG_EMPTY);
   2049 
   2050 /* This is the same but it checks a complete string and returns true
   2051 * only if it just contains a floating point number.  As of 1.5.4 this
   2052 * function also returns the state at the end of parsing the number if
   2053 * it was valid (otherwise it returns 0.)  This can be used for testing
   2054 * for negative or zero values using the sticky flag.
   2055 */
   2056 PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
   2057   size_t size),PNG_EMPTY);
   2058 #endif /* pCAL || sCAL */
   2059 
   2060 #if defined(PNG_READ_GAMMA_SUPPORTED) ||\
   2061    defined(PNG_COLORSPACE_SUPPORTED) ||\
   2062    defined(PNG_INCH_CONVERSIONS_SUPPORTED) ||\
   2063    defined(PNG_READ_pHYs_SUPPORTED)
   2064 /* Added at libpng version 1.5.0 */
   2065 /* This is a utility to provide a*times/div (rounded) and indicate
   2066 * if there is an overflow.  The result is a boolean - false (0)
   2067 * for overflow, true (1) if no overflow, in which case *res
   2068 * holds the result.
   2069 */
   2070 PNG_INTERNAL_FUNCTION(int,png_muldiv,(png_fixed_point_p res, png_fixed_point a,
   2071   png_int_32 multiplied_by, png_int_32 divided_by),PNG_EMPTY);
   2072 
   2073 /* Calculate a reciprocal - used for gamma values.  This returns
   2074 * 0 if the argument is 0 in order to maintain an undefined value;
   2075 * there are no warnings.
   2076 */
   2077 PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal,(png_fixed_point a),
   2078   PNG_EMPTY);
   2079 #endif
   2080 
   2081 #ifdef PNG_READ_GAMMA_SUPPORTED
   2082 /* The same but gives a reciprocal of the product of two fixed point
   2083 * values.  Accuracy is suitable for gamma calculations but this is
   2084 * not exact - use png_muldiv for that.  Only required at present on read.
   2085 */
   2086 PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal2,(png_fixed_point a,
   2087   png_fixed_point b),PNG_EMPTY);
   2088 
   2089 /* Return true if the gamma value is significantly different from 1.0 */
   2090 PNG_INTERNAL_FUNCTION(int,png_gamma_significant,(png_fixed_point gamma_value),
   2091   PNG_EMPTY);
   2092 
   2093 /* PNGv3: 'resolve' the file gamma according to the new PNGv3 rules for colour
   2094 * space information.
   2095 *
   2096 * NOTE: this uses precisely those chunks that libpng supports.  For example it
   2097 * doesn't use iCCP and it can only use cICP for known and manageable
   2098 * transforms.  For this reason a gamma specified by png_set_gamma always takes
   2099 * precedence.
   2100 */
   2101 PNG_INTERNAL_FUNCTION(png_fixed_point,png_resolve_file_gamma,
   2102   (png_const_structrp png_ptr),PNG_EMPTY);
   2103 
   2104 /* Internal fixed point gamma correction.  These APIs are called as
   2105 * required to convert single values - they don't need to be fast,
   2106 * they are not used when processing image pixel values.
   2107 *
   2108 * While the input is an 'unsigned' value it must actually be the
   2109 * correct bit value - 0..255 or 0..65535 as required.
   2110 */
   2111 PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_correct,(png_structrp png_ptr,
   2112   unsigned int value, png_fixed_point gamma_value),PNG_EMPTY);
   2113 PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_16bit_correct,(unsigned int value,
   2114   png_fixed_point gamma_value),PNG_EMPTY);
   2115 PNG_INTERNAL_FUNCTION(png_byte,png_gamma_8bit_correct,(unsigned int value,
   2116   png_fixed_point gamma_value),PNG_EMPTY);
   2117 PNG_INTERNAL_FUNCTION(void,png_destroy_gamma_table,(png_structrp png_ptr),
   2118   PNG_EMPTY);
   2119 PNG_INTERNAL_FUNCTION(void,png_build_gamma_table,(png_structrp png_ptr,
   2120   int bit_depth),PNG_EMPTY);
   2121 #endif /* READ_GAMMA */
   2122 
   2123 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
   2124 /* Set the RGB coefficients if not already set by png_set_rgb_to_gray */
   2125 PNG_INTERNAL_FUNCTION(void,png_set_rgb_coefficients,(png_structrp png_ptr),
   2126   PNG_EMPTY);
   2127 #endif
   2128 
   2129 #if defined(PNG_cHRM_SUPPORTED) || defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
   2130 PNG_INTERNAL_FUNCTION(int,png_XYZ_from_xy,(png_XYZ *XYZ, const png_xy *xy),
   2131   PNG_EMPTY);
   2132 #endif /* cHRM || READ_RGB_TO_GRAY */
   2133 
   2134 #ifdef PNG_COLORSPACE_SUPPORTED
   2135 PNG_INTERNAL_FUNCTION(int,png_xy_from_XYZ,(png_xy *xy, const png_XYZ *XYZ),
   2136   PNG_EMPTY);
   2137 #endif
   2138 
   2139 /* SIMPLIFIED READ/WRITE SUPPORT */
   2140 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   2141   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
   2142 /* The internal structure that png_image::opaque points to. */
   2143 typedef struct png_control
   2144 {
   2145   png_structp png_ptr;
   2146   png_infop   info_ptr;
   2147   png_voidp   error_buf;           /* Always a jmp_buf at present. */
   2148 
   2149   png_const_bytep memory;          /* Memory buffer. */
   2150   size_t          size;            /* Size of the memory buffer. */
   2151 
   2152   unsigned int for_write       :1; /* Otherwise it is a read structure */
   2153   unsigned int owned_file      :1; /* We own the file in io_ptr */
   2154 } png_control;
   2155 
   2156 /* Return the pointer to the jmp_buf from a png_control: necessary because C
   2157 * does not reveal the type of the elements of jmp_buf.
   2158 */
   2159 #ifdef __cplusplus
   2160 #  define png_control_jmp_buf(pc) (((jmp_buf*)((pc)->error_buf))[0])
   2161 #else
   2162 #  define png_control_jmp_buf(pc) ((pc)->error_buf)
   2163 #endif
   2164 
   2165 /* Utility to safely execute a piece of libpng code catching and logging any
   2166 * errors that might occur.  Returns true on success, false on failure (either
   2167 * of the function or as a result of a png_error.)
   2168 */
   2169 PNG_INTERNAL_CALLBACK(void,png_safe_error,(png_structp png_ptr,
   2170   png_const_charp error_message),PNG_NORETURN);
   2171 
   2172 #ifdef PNG_WARNINGS_SUPPORTED
   2173 PNG_INTERNAL_CALLBACK(void,png_safe_warning,(png_structp png_ptr,
   2174   png_const_charp warning_message),PNG_EMPTY);
   2175 #else
   2176 #  define png_safe_warning 0/*dummy argument*/
   2177 #endif
   2178 
   2179 PNG_INTERNAL_FUNCTION(int,png_safe_execute,(png_imagep image,
   2180   int (*function)(png_voidp), png_voidp arg),PNG_EMPTY);
   2181 
   2182 /* Utility to log an error; this also cleans up the png_image; the function
   2183 * always returns 0 (false).
   2184 */
   2185 PNG_INTERNAL_FUNCTION(int,png_image_error,(png_imagep image,
   2186   png_const_charp error_message),PNG_EMPTY);
   2187 
   2188 #ifndef PNG_SIMPLIFIED_READ_SUPPORTED
   2189 /* png_image_free is used by the write code but not exported */
   2190 PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
   2191 #endif /* !SIMPLIFIED_READ */
   2192 
   2193 #endif /* SIMPLIFIED READ/WRITE */
   2194 
   2195 /* These are initialization functions for hardware specific PNG filter
   2196 * optimizations; list these here then select the appropriate one at compile
   2197 * time using the macro PNG_FILTER_OPTIMIZATIONS.  If the macro is not defined
   2198 * the generic code is used.
   2199 */
   2200 #ifdef PNG_FILTER_OPTIMIZATIONS
   2201 PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
   2202   unsigned int bpp), PNG_EMPTY);
   2203   /* Just declare the optimization that will be used */
   2204 #else
   2205   /* List *all* the possible optimizations here - this branch is required if
   2206    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
   2207    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
   2208    */
   2209 #  if PNG_ARM_NEON_OPT > 0
   2210 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   2211   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2212 #endif
   2213 
   2214 #if PNG_MIPS_MSA_IMPLEMENTATION == 1
   2215 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_mips,
   2216   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2217 #endif
   2218 
   2219 #  if PNG_MIPS_MMI_IMPLEMENTATION > 0
   2220 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_mips,
   2221   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2222 #  endif
   2223 
   2224 #  if PNG_INTEL_SSE_IMPLEMENTATION > 0
   2225 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
   2226   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2227 #  endif
   2228 #endif
   2229 
   2230 #if PNG_LOONGARCH_LSX_OPT > 0
   2231 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_lsx,
   2232    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2233 #endif
   2234 
   2235 #  if PNG_RISCV_RVV_IMPLEMENTATION == 1
   2236 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_rvv,
   2237   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
   2238 #endif
   2239 
   2240 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
   2241   png_const_charp key, png_bytep new_key), PNG_EMPTY);
   2242 
   2243 #if PNG_ARM_NEON_IMPLEMENTATION == 1
   2244 PNG_INTERNAL_FUNCTION(void,
   2245                      png_riffle_palette_neon,
   2246                      (png_structrp),
   2247                      PNG_EMPTY);
   2248 PNG_INTERNAL_FUNCTION(int,
   2249                      png_do_expand_palette_rgba8_neon,
   2250                      (png_structrp,
   2251                       png_row_infop,
   2252                       png_const_bytep,
   2253                       const png_bytepp,
   2254                       const png_bytepp),
   2255                      PNG_EMPTY);
   2256 PNG_INTERNAL_FUNCTION(int,
   2257                      png_do_expand_palette_rgb8_neon,
   2258                      (png_structrp,
   2259                       png_row_infop,
   2260                       png_const_bytep,
   2261                       const png_bytepp,
   2262                       const png_bytepp),
   2263                      PNG_EMPTY);
   2264 #endif
   2265 
   2266 /* Maintainer: Put new private prototypes here ^ */
   2267 
   2268 #include "pngdebug.h"
   2269 
   2270 #ifdef __cplusplus
   2271 }
   2272 #endif
   2273 
   2274 #endif /* PNG_VERSION_INFO_ONLY */