1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.  Oracle designates this
   7  * particular file as subject to the "Classpath" exception as provided
   8  * by Oracle in the LICENSE file that accompanied this code.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  */
  24 
  25 /* pngconf.h - machine configurable file for libpng
  26  *
  27  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file and, per its terms, should not be removed:
  31  *
  32  * libpng version 1.6.35, July 15, 2018
  33  *
  34  * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
  35  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  36  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  37  *
  38  * This code is released under the libpng license.
  39  * For conditions of distribution and use, see the disclaimer
  40  * and license in png.h
  41  *
  42  * Any machine specific code is near the front of this file, so if you
  43  * are configuring libpng for a machine, you may want to read the section
  44  * starting here down to where it starts to typedef png_color, png_text,
  45  * and png_info.
  46  */
  47 
  48 #ifndef PNGCONF_H
  49 #define PNGCONF_H
  50 
  51 #ifndef PNG_BUILDING_SYMBOL_TABLE /* else includes may cause problems */
  52 
  53 /* From libpng 1.6.0 libpng requires an ANSI X3.159-1989 ("ISOC90") compliant C
  54  * compiler for correct compilation.  The following header files are required by
  55  * the standard.  If your compiler doesn't provide these header files, or they
  56  * do not match the standard, you will need to provide/improve them.
  57  */
  58 #include <limits.h>
  59 #include <stddef.h>
  60 
  61 /* Library header files.  These header files are all defined by ISOC90; libpng
  62  * expects conformant implementations, however, an ISOC90 conformant system need
  63  * not provide these header files if the functionality cannot be implemented.
  64  * In this case it will be necessary to disable the relevant parts of libpng in
  65  * the build of pnglibconf.h.
  66  *
  67  * Prior to 1.6.0 string.h was included here; the API changes in 1.6.0 to not
  68  * include this unnecessary header file.
  69  */
  70 
  71 #ifdef PNG_STDIO_SUPPORTED
  72    /* Required for the definition of FILE: */
  73 #  include <stdio.h>
  74 #endif
  75 
  76 #ifdef PNG_SETJMP_SUPPORTED
  77    /* Required for the definition of jmp_buf and the declaration of longjmp: */
  78 #  include <setjmp.h>
  79 #endif
  80 
  81 #ifdef PNG_CONVERT_tIME_SUPPORTED
  82    /* Required for struct tm: */
  83 #  include <time.h>
  84 #endif
  85 
  86 #endif /* PNG_BUILDING_SYMBOL_TABLE */
  87 
  88 /* Prior to 1.6.0 it was possible to turn off 'const' in declarations using
  89  * PNG_NO_CONST; this is no longer supported except for data declarations which
  90  * apparently still cause problems in 2011 on some compilers.
  91  */
  92 #define PNG_CONST const /* backward compatibility only */
  93 
  94 /* This controls optimization of the reading of 16-bit and 32-bit values
  95  * from PNG files.  It can be set on a per-app-file basis - it
  96  * just changes whether a macro is used when the function is called.
  97  * The library builder sets the default; if read functions are not
  98  * built into the library the macro implementation is forced on.
  99  */
 100 #ifndef PNG_READ_INT_FUNCTIONS_SUPPORTED
 101 #  define PNG_USE_READ_MACROS
 102 #endif
 103 #if !defined(PNG_NO_USE_READ_MACROS) && !defined(PNG_USE_READ_MACROS)
 104 #  if PNG_DEFAULT_READ_MACROS
 105 #    define PNG_USE_READ_MACROS
 106 #  endif
 107 #endif
 108 
 109 /* COMPILER SPECIFIC OPTIONS.
 110  *
 111  * These options are provided so that a variety of difficult compilers
 112  * can be used.  Some are fixed at build time (e.g. PNG_API_RULE
 113  * below) but still have compiler specific implementations, others
 114  * may be changed on a per-file basis when compiling against libpng.
 115  */
 116 
 117 /* The PNGARG macro was used in versions of libpng prior to 1.6.0 to protect
 118  * against legacy (pre ISOC90) compilers that did not understand function
 119  * prototypes.  It is not required for modern C compilers.
 120  */
 121 #ifndef PNGARG
 122 #  define PNGARG(arglist) arglist
 123 #endif
 124 
 125 /* Function calling conventions.
 126  * =============================
 127  * Normally it is not necessary to specify to the compiler how to call
 128  * a function - it just does it - however on x86 systems derived from
 129  * Microsoft and Borland C compilers ('IBM PC', 'DOS', 'Windows' systems
 130  * and some others) there are multiple ways to call a function and the
 131  * default can be changed on the compiler command line.  For this reason
 132  * libpng specifies the calling convention of every exported function and
 133  * every function called via a user supplied function pointer.  This is
 134  * done in this file by defining the following macros:
 135  *
 136  * PNGAPI    Calling convention for exported functions.
 137  * PNGCBAPI  Calling convention for user provided (callback) functions.
 138  * PNGCAPI   Calling convention used by the ANSI-C library (required
 139  *           for longjmp callbacks and sometimes used internally to
 140  *           specify the calling convention for zlib).
 141  *
 142  * These macros should never be overridden.  If it is necessary to
 143  * change calling convention in a private build this can be done
 144  * by setting PNG_API_RULE (which defaults to 0) to one of the values
 145  * below to select the correct 'API' variants.
 146  *
 147  * PNG_API_RULE=0 Use PNGCAPI - the 'C' calling convention - throughout.
 148  *                This is correct in every known environment.
 149  * PNG_API_RULE=1 Use the operating system convention for PNGAPI and
 150  *                the 'C' calling convention (from PNGCAPI) for
 151  *                callbacks (PNGCBAPI).  This is no longer required
 152  *                in any known environment - if it has to be used
 153  *                please post an explanation of the problem to the
 154  *                libpng mailing list.
 155  *
 156  * These cases only differ if the operating system does not use the C
 157  * calling convention, at present this just means the above cases
 158  * (x86 DOS/Windows systems) and, even then, this does not apply to
 159  * Cygwin running on those systems.
 160  *
 161  * Note that the value must be defined in pnglibconf.h so that what
 162  * the application uses to call the library matches the conventions
 163  * set when building the library.
 164  */
 165 
 166 /* Symbol export
 167  * =============
 168  * When building a shared library it is almost always necessary to tell
 169  * the compiler which symbols to export.  The png.h macro 'PNG_EXPORT'
 170  * is used to mark the symbols.  On some systems these symbols can be
 171  * extracted at link time and need no special processing by the compiler,
 172  * on other systems the symbols are flagged by the compiler and just
 173  * the declaration requires a special tag applied (unfortunately) in a
 174  * compiler dependent way.  Some systems can do either.
 175  *
 176  * A small number of older systems also require a symbol from a DLL to
 177  * be flagged to the program that calls it.  This is a problem because
 178  * we do not know in the header file included by application code that
 179  * the symbol will come from a shared library, as opposed to a statically
 180  * linked one.  For this reason the application must tell us by setting
 181  * the magic flag PNG_USE_DLL to turn on the special processing before
 182  * it includes png.h.
 183  *
 184  * Four additional macros are used to make this happen:
 185  *
 186  * PNG_IMPEXP The magic (if any) to cause a symbol to be exported from
 187  *            the build or imported if PNG_USE_DLL is set - compiler
 188  *            and system specific.
 189  *
 190  * PNG_EXPORT_TYPE(type) A macro that pre or appends PNG_IMPEXP to
 191  *                       'type', compiler specific.
 192  *
 193  * PNG_DLL_EXPORT Set to the magic to use during a libpng build to
 194  *                make a symbol exported from the DLL.  Not used in the
 195  *                public header files; see pngpriv.h for how it is used
 196  *                in the libpng build.
 197  *
 198  * PNG_DLL_IMPORT Set to the magic to force the libpng symbols to come
 199  *                from a DLL - used to define PNG_IMPEXP when
 200  *                PNG_USE_DLL is set.
 201  */
 202 
 203 /* System specific discovery.
 204  * ==========================
 205  * This code is used at build time to find PNG_IMPEXP, the API settings
 206  * and PNG_EXPORT_TYPE(), it may also set a macro to indicate the DLL
 207  * import processing is possible.  On Windows systems it also sets
 208  * compiler-specific macros to the values required to change the calling
 209  * conventions of the various functions.
 210  */
 211 #if defined(_Windows) || defined(_WINDOWS) || defined(WIN32) ||\
 212     defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__)
 213   /* Windows system (DOS doesn't support DLLs).  Includes builds under Cygwin or
 214    * MinGW on any architecture currently supported by Windows.  Also includes
 215    * Watcom builds but these need special treatment because they are not
 216    * compatible with GCC or Visual C because of different calling conventions.
 217    */
 218 #  if PNG_API_RULE == 2
 219    /* If this line results in an error, either because __watcall is not
 220     * understood or because of a redefine just below you cannot use *this*
 221     * build of the library with the compiler you are using.  *This* build was
 222     * build using Watcom and applications must also be built using Watcom!
 223     */
 224 #    define PNGCAPI __watcall
 225 #  endif
 226 
 227 #  if defined(__GNUC__) || (defined(_MSC_VER) && (_MSC_VER >= 800))
 228 #    define PNGCAPI __cdecl
 229 #    if PNG_API_RULE == 1
 230    /* If this line results in an error __stdcall is not understood and
 231     * PNG_API_RULE should not have been set to '1'.
 232     */
 233 #      define PNGAPI __stdcall
 234 #    endif
 235 #  else
 236    /* An older compiler, or one not detected (erroneously) above,
 237     * if necessary override on the command line to get the correct
 238     * variants for the compiler.
 239     */
 240 #    ifndef PNGCAPI
 241 #      define PNGCAPI _cdecl
 242 #    endif
 243 #    if PNG_API_RULE == 1 && !defined(PNGAPI)
 244 #      define PNGAPI _stdcall
 245 #    endif
 246 #  endif /* compiler/api */
 247 
 248   /* NOTE: PNGCBAPI always defaults to PNGCAPI. */
 249 
 250 #  if defined(PNGAPI) && !defined(PNG_USER_PRIVATEBUILD)
 251 #     error "PNG_USER_PRIVATEBUILD must be defined if PNGAPI is changed"
 252 #  endif
 253 
 254 #  if (defined(_MSC_VER) && _MSC_VER < 800) ||\
 255       (defined(__BORLANDC__) && __BORLANDC__ < 0x500)
 256    /* older Borland and MSC
 257     * compilers used '__export' and required this to be after
 258     * the type.
 259     */
 260 #    ifndef PNG_EXPORT_TYPE
 261 #      define PNG_EXPORT_TYPE(type) type PNG_IMPEXP
 262 #    endif
 263 #    define PNG_DLL_EXPORT __export
 264 #  else /* newer compiler */
 265 #    define PNG_DLL_EXPORT __declspec(dllexport)
 266 #    ifndef PNG_DLL_IMPORT
 267 #      define PNG_DLL_IMPORT __declspec(dllimport)
 268 #    endif
 269 #  endif /* compiler */
 270 
 271 #else /* !Windows */
 272 #  if (defined(__IBMC__) || defined(__IBMCPP__)) && defined(__OS2__)
 273 #    define PNGAPI _System
 274 #  else /* !Windows/x86 && !OS/2 */
 275    /* Use the defaults, or define PNG*API on the command line (but
 276     * this will have to be done for every compile!)
 277     */
 278 #  endif /* other system, !OS/2 */
 279 #endif /* !Windows/x86 */
 280 
 281 /* Now do all the defaulting . */
 282 #ifndef PNGCAPI
 283 #  define PNGCAPI
 284 #endif
 285 #ifndef PNGCBAPI
 286 #  define PNGCBAPI PNGCAPI
 287 #endif
 288 #ifndef PNGAPI
 289 #  define PNGAPI PNGCAPI
 290 #endif
 291 
 292 /* PNG_IMPEXP may be set on the compilation system command line or (if not set)
 293  * then in an internal header file when building the library, otherwise (when
 294  * using the library) it is set here.
 295  */
 296 #ifndef PNG_IMPEXP
 297 #  if defined(PNG_USE_DLL) && defined(PNG_DLL_IMPORT)
 298    /* This forces use of a DLL, disallowing static linking */
 299 #    define PNG_IMPEXP PNG_DLL_IMPORT
 300 #  endif
 301 
 302 #  ifndef PNG_IMPEXP
 303 #    define PNG_IMPEXP
 304 #  endif
 305 #endif
 306 
 307 /* In 1.5.2 the definition of PNG_FUNCTION has been changed to always treat
 308  * 'attributes' as a storage class - the attributes go at the start of the
 309  * function definition, and attributes are always appended regardless of the
 310  * compiler.  This considerably simplifies these macros but may cause problems
 311  * if any compilers both need function attributes and fail to handle them as
 312  * a storage class (this is unlikely.)
 313  */
 314 #ifndef PNG_FUNCTION
 315 #  define PNG_FUNCTION(type, name, args, attributes) attributes type name args
 316 #endif
 317 
 318 #ifndef PNG_EXPORT_TYPE
 319 #  define PNG_EXPORT_TYPE(type) PNG_IMPEXP type
 320 #endif
 321 
 322    /* The ordinal value is only relevant when preprocessing png.h for symbol
 323     * table entries, so we discard it here.  See the .dfn files in the
 324     * scripts directory.
 325     */
 326 
 327 #ifndef PNG_EXPORTA
 328 #  define PNG_EXPORTA(ordinal, type, name, args, attributes) \
 329       PNG_FUNCTION(PNG_EXPORT_TYPE(type), (PNGAPI name), PNGARG(args), \
 330       PNG_LINKAGE_API attributes)
 331 #endif
 332 
 333 /* ANSI-C (C90) does not permit a macro to be invoked with an empty argument,
 334  * so make something non-empty to satisfy the requirement:
 335  */
 336 #define PNG_EMPTY /*empty list*/
 337 
 338 #define PNG_EXPORT(ordinal, type, name, args) \
 339    PNG_EXPORTA(ordinal, type, name, args, PNG_EMPTY)
 340 
 341 /* Use PNG_REMOVED to comment out a removed interface. */
 342 #ifndef PNG_REMOVED
 343 #  define PNG_REMOVED(ordinal, type, name, args, attributes)
 344 #endif
 345 
 346 #ifndef PNG_CALLBACK
 347 #  define PNG_CALLBACK(type, name, args) type (PNGCBAPI name) PNGARG(args)
 348 #endif
 349 
 350 /* Support for compiler specific function attributes.  These are used
 351  * so that where compiler support is available incorrect use of API
 352  * functions in png.h will generate compiler warnings.
 353  *
 354  * Added at libpng-1.2.41.
 355  */
 356 
 357 #ifndef PNG_NO_PEDANTIC_WARNINGS
 358 #  ifndef PNG_PEDANTIC_WARNINGS_SUPPORTED
 359 #    define PNG_PEDANTIC_WARNINGS_SUPPORTED
 360 #  endif
 361 #endif
 362 
 363 #ifdef PNG_PEDANTIC_WARNINGS_SUPPORTED
 364   /* Support for compiler specific function attributes.  These are used
 365    * so that where compiler support is available, incorrect use of API
 366    * functions in png.h will generate compiler warnings.  Added at libpng
 367    * version 1.2.41.  Disabling these removes the warnings but may also produce
 368    * less efficient code.
 369    */
 370 #  if defined(__clang__) && defined(__has_attribute)
 371    /* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
 372 #    if !defined(PNG_USE_RESULT) && __has_attribute(__warn_unused_result__)
 373 #      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
 374 #    endif
 375 #    if !defined(PNG_NORETURN) && __has_attribute(__noreturn__)
 376 #      define PNG_NORETURN __attribute__((__noreturn__))
 377 #    endif
 378 #    if !defined(PNG_ALLOCATED) && __has_attribute(__malloc__)
 379 #      define PNG_ALLOCATED __attribute__((__malloc__))
 380 #    endif
 381 #    if !defined(PNG_DEPRECATED) && __has_attribute(__deprecated__)
 382 #      define PNG_DEPRECATED __attribute__((__deprecated__))
 383 #    endif
 384 #    if !defined(PNG_PRIVATE)
 385 #      ifdef __has_extension
 386 #        if __has_extension(attribute_unavailable_with_message)
 387 #          define PNG_PRIVATE __attribute__((__unavailable__(\
 388              "This function is not exported by libpng.")))
 389 #        endif
 390 #      endif
 391 #    endif
 392 #    ifndef PNG_RESTRICT
 393 #      define PNG_RESTRICT __restrict
 394 #    endif
 395 
 396 #  elif defined(__GNUC__)
 397 #    ifndef PNG_USE_RESULT
 398 #      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
 399 #    endif
 400 #    ifndef PNG_NORETURN
 401 #      define PNG_NORETURN   __attribute__((__noreturn__))
 402 #    endif
 403 #    if __GNUC__ >= 3
 404 #      ifndef PNG_ALLOCATED
 405 #        define PNG_ALLOCATED  __attribute__((__malloc__))
 406 #      endif
 407 #      ifndef PNG_DEPRECATED
 408 #        define PNG_DEPRECATED __attribute__((__deprecated__))
 409 #      endif
 410 #      ifndef PNG_PRIVATE
 411 #        if 0 /* Doesn't work so we use deprecated instead*/
 412 #          define PNG_PRIVATE \
 413             __attribute__((warning("This function is not exported by libpng.")))
 414 #        else
 415 #          define PNG_PRIVATE \
 416             __attribute__((__deprecated__))
 417 #        endif
 418 #      endif
 419 #      if ((__GNUC__ > 3) || !defined(__GNUC_MINOR__) || (__GNUC_MINOR__ >= 1))
 420 #        ifndef PNG_RESTRICT
 421 #          define PNG_RESTRICT __restrict
 422 #        endif
 423 #      endif /* __GNUC__.__GNUC_MINOR__ > 3.0 */
 424 #    endif /* __GNUC__ >= 3 */
 425 
 426 #  elif defined(_MSC_VER)  && (_MSC_VER >= 1300)
 427 #    ifndef PNG_USE_RESULT
 428 #      define PNG_USE_RESULT /* not supported */
 429 #    endif
 430 #    ifndef PNG_NORETURN
 431 #      define PNG_NORETURN   __declspec(noreturn)
 432 #    endif
 433 #    ifndef PNG_ALLOCATED
 434 #      if (_MSC_VER >= 1400)
 435 #        define PNG_ALLOCATED __declspec(restrict)
 436 #      endif
 437 #    endif
 438 #    ifndef PNG_DEPRECATED
 439 #      define PNG_DEPRECATED __declspec(deprecated)
 440 #    endif
 441 #    ifndef PNG_PRIVATE
 442 #      define PNG_PRIVATE __declspec(deprecated)
 443 #    endif
 444 #    ifndef PNG_RESTRICT
 445 #      if (_MSC_VER >= 1400)
 446 #        define PNG_RESTRICT __restrict
 447 #      endif
 448 #    endif
 449 
 450 #  elif defined(__WATCOMC__)
 451 #    ifndef PNG_RESTRICT
 452 #      define PNG_RESTRICT __restrict
 453 #    endif
 454 #  endif
 455 #endif /* PNG_PEDANTIC_WARNINGS */
 456 
 457 #ifndef PNG_DEPRECATED
 458 #  define PNG_DEPRECATED  /* Use of this function is deprecated */
 459 #endif
 460 #ifndef PNG_USE_RESULT
 461 #  define PNG_USE_RESULT  /* The result of this function must be checked */
 462 #endif
 463 #ifndef PNG_NORETURN
 464 #  define PNG_NORETURN    /* This function does not return */
 465 #endif
 466 #ifndef PNG_ALLOCATED
 467 #  define PNG_ALLOCATED   /* The result of the function is new memory */
 468 #endif
 469 #ifndef PNG_PRIVATE
 470 #  define PNG_PRIVATE     /* This is a private libpng function */
 471 #endif
 472 #ifndef PNG_RESTRICT
 473 #  define PNG_RESTRICT    /* The C99 "restrict" feature */
 474 #endif
 475 
 476 #ifndef PNG_FP_EXPORT     /* A floating point API. */
 477 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 478 #     define PNG_FP_EXPORT(ordinal, type, name, args)\
 479          PNG_EXPORT(ordinal, type, name, args);
 480 #  else                   /* No floating point APIs */
 481 #     define PNG_FP_EXPORT(ordinal, type, name, args)
 482 #  endif
 483 #endif
 484 #ifndef PNG_FIXED_EXPORT  /* A fixed point API. */
 485 #  ifdef PNG_FIXED_POINT_SUPPORTED
 486 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
 487          PNG_EXPORT(ordinal, type, name, args);
 488 #  else                   /* No fixed point APIs */
 489 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)
 490 #  endif
 491 #endif
 492 
 493 #ifndef PNG_BUILDING_SYMBOL_TABLE
 494 /* Some typedefs to get us started.  These should be safe on most of the common
 495  * platforms.
 496  *
 497  * png_uint_32 and png_int_32 may, currently, be larger than required to hold a
 498  * 32-bit value however this is not normally advisable.
 499  *
 500  * png_uint_16 and png_int_16 should always be two bytes in size - this is
 501  * verified at library build time.
 502  *
 503  * png_byte must always be one byte in size.
 504  *
 505  * The checks below use constants from limits.h, as defined by the ISOC90
 506  * standard.
 507  */
 508 #if CHAR_BIT == 8 && UCHAR_MAX == 255
 509    typedef unsigned char png_byte;
 510 #else
 511 #  error "libpng requires 8-bit bytes"
 512 #endif
 513 
 514 #if INT_MIN == -32768 && INT_MAX == 32767
 515    typedef int png_int_16;
 516 #elif SHRT_MIN == -32768 && SHRT_MAX == 32767
 517    typedef short png_int_16;
 518 #else
 519 #  error "libpng requires a signed 16-bit type"
 520 #endif
 521 
 522 #if UINT_MAX == 65535
 523    typedef unsigned int png_uint_16;
 524 #elif USHRT_MAX == 65535
 525    typedef unsigned short png_uint_16;
 526 #else
 527 #  error "libpng requires an unsigned 16-bit type"
 528 #endif
 529 
 530 #if INT_MIN < -2147483646 && INT_MAX > 2147483646
 531    typedef int png_int_32;
 532 #elif LONG_MIN < -2147483646 && LONG_MAX > 2147483646
 533    typedef long int png_int_32;
 534 #else
 535 #  error "libpng requires a signed 32-bit (or more) type"
 536 #endif
 537 
 538 #if UINT_MAX > 4294967294U
 539    typedef unsigned int png_uint_32;
 540 #elif ULONG_MAX > 4294967294U
 541    typedef unsigned long int png_uint_32;
 542 #else
 543 #  error "libpng requires an unsigned 32-bit (or more) type"
 544 #endif
 545 
 546 /* Prior to 1.6.0, it was possible to disable the use of size_t and ptrdiff_t.
 547  * From 1.6.0 onwards, an ISO C90 compiler, as well as a standard-compliant
 548  * behavior of sizeof and ptrdiff_t are required.
 549  * The legacy typedefs are provided here for backwards compatibility.
 550  */
 551 typedef size_t png_size_t;
 552 typedef ptrdiff_t png_ptrdiff_t;
 553 
 554 /* libpng needs to know the maximum value of 'size_t' and this controls the
 555  * definition of png_alloc_size_t, below.  This maximum value of size_t limits
 556  * but does not control the maximum allocations the library makes - there is
 557  * direct application control of this through png_set_user_limits().
 558  */
 559 #ifndef PNG_SMALL_SIZE_T
 560    /* Compiler specific tests for systems where size_t is known to be less than
 561     * 32 bits (some of these systems may no longer work because of the lack of
 562     * 'far' support; see above.)
 563     */
 564 #  if (defined(__TURBOC__) && !defined(__FLAT__)) ||\
 565    (defined(_MSC_VER) && defined(MAXSEG_64K))
 566 #     define PNG_SMALL_SIZE_T
 567 #  endif
 568 #endif
 569 
 570 /* png_alloc_size_t is guaranteed to be no smaller than size_t, and no smaller
 571  * than png_uint_32.  Casts from size_t or png_uint_32 to png_alloc_size_t are
 572  * not necessary; in fact, it is recommended not to use them at all, so that
 573  * the compiler can complain when something turns out to be problematic.
 574  *
 575  * Casts in the other direction (from png_alloc_size_t to size_t or
 576  * png_uint_32) should be explicitly applied; however, we do not expect to
 577  * encounter practical situations that require such conversions.
 578  *
 579  * PNG_SMALL_SIZE_T must be defined if the maximum value of size_t is less than
 580  * 4294967295 - i.e. less than the maximum value of png_uint_32.
 581  */
 582 #ifdef PNG_SMALL_SIZE_T
 583    typedef png_uint_32 png_alloc_size_t;
 584 #else
 585    typedef size_t png_alloc_size_t;
 586 #endif
 587 
 588 /* Prior to 1.6.0 libpng offered limited support for Microsoft C compiler
 589  * implementations of Intel CPU specific support of user-mode segmented address
 590  * spaces, where 16-bit pointers address more than 65536 bytes of memory using
 591  * separate 'segment' registers.  The implementation requires two different
 592  * types of pointer (only one of which includes the segment value.)
 593  *
 594  * If required this support is available in version 1.2 of libpng and may be
 595  * available in versions through 1.5, although the correctness of the code has
 596  * not been verified recently.
 597  */
 598 
 599 /* Typedef for floating-point numbers that are converted to fixed-point with a
 600  * multiple of 100,000, e.g., gamma
 601  */
 602 typedef png_int_32 png_fixed_point;
 603 
 604 /* Add typedefs for pointers */
 605 typedef void                  * png_voidp;
 606 typedef const void            * png_const_voidp;
 607 typedef png_byte              * png_bytep;
 608 typedef const png_byte        * png_const_bytep;
 609 typedef png_uint_32           * png_uint_32p;
 610 typedef const png_uint_32     * png_const_uint_32p;
 611 typedef png_int_32            * png_int_32p;
 612 typedef const png_int_32      * png_const_int_32p;
 613 typedef png_uint_16           * png_uint_16p;
 614 typedef const png_uint_16     * png_const_uint_16p;
 615 typedef png_int_16            * png_int_16p;
 616 typedef const png_int_16      * png_const_int_16p;
 617 typedef char                  * png_charp;
 618 typedef const char            * png_const_charp;
 619 typedef png_fixed_point       * png_fixed_point_p;
 620 typedef const png_fixed_point * png_const_fixed_point_p;
 621 typedef size_t                * png_size_tp;
 622 typedef const size_t          * png_const_size_tp;
 623 
 624 #ifdef PNG_STDIO_SUPPORTED
 625 typedef FILE            * png_FILE_p;
 626 #endif
 627 
 628 #ifdef PNG_FLOATING_POINT_SUPPORTED
 629 typedef double       * png_doublep;
 630 typedef const double * png_const_doublep;
 631 #endif
 632 
 633 /* Pointers to pointers; i.e. arrays */
 634 typedef png_byte        * * png_bytepp;
 635 typedef png_uint_32     * * png_uint_32pp;
 636 typedef png_int_32      * * png_int_32pp;
 637 typedef png_uint_16     * * png_uint_16pp;
 638 typedef png_int_16      * * png_int_16pp;
 639 typedef const char      * * png_const_charpp;
 640 typedef char            * * png_charpp;
 641 typedef png_fixed_point * * png_fixed_point_pp;
 642 #ifdef PNG_FLOATING_POINT_SUPPORTED
 643 typedef double          * * png_doublepp;
 644 #endif
 645 
 646 /* Pointers to pointers to pointers; i.e., pointer to array */
 647 typedef char            * * * png_charppp;
 648 
 649 #endif /* PNG_BUILDING_SYMBOL_TABLE */
 650 
 651 #endif /* PNGCONF_H */