src/png/png.c

   1
   2 /* png.c - location for general purpose libpng functions
   3  *
   4  * libpng version 1.2.6 - August 15, 2004
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1998-2004 Glenn Randers-Pehrson
   7  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   8  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   9  */
  10
  11 #define PNG_INTERNAL
  12 #define PNG_NO_EXTERN
  13 #include "png.h"
  14
  15 /* Generate a compiler error if there is an old png.h in the search path. */
  16 typedef version_1_2_6 Your_png_h_is_not_version_1_2_6;
  17
  18 /* Version information for C files.  This had better match the version
  19  * string defined in png.h.  */
  20
  21 #ifdef PNG_USE_GLOBAL_ARRAYS
  22 /* png_libpng_ver was changed to a function in version 1.0.5c */
  23 const char png_libpng_ver[18] = PNG_LIBPNG_VER_STRING;
  24
  25 /* png_sig was changed to a function in version 1.0.5c */
  26 /* Place to hold the signature string for a PNG file. */
  27 const png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
  28
  29 /* Invoke global declarations for constant strings for known chunk types */
  30 PNG_IHDR;
  31 PNG_IDAT;
  32 PNG_IEND;
  33 PNG_PLTE;
  34 PNG_bKGD;
  35 PNG_cHRM;
  36 PNG_gAMA;
  37 PNG_hIST;
  38 PNG_iCCP;
  39 PNG_iTXt;
  40 PNG_oFFs;
  41 PNG_pCAL;
  42 PNG_sCAL;
  43 PNG_pHYs;
  44 PNG_sBIT;
  45 PNG_sPLT;
  46 PNG_sRGB;
  47 PNG_tEXt;
  48 PNG_tIME;
  49 PNG_tRNS;
  50 PNG_zTXt;
  51
  52 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
  53
  54 /* start of interlace block */
  55 const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
  56
  57 /* offset to next interlace block */
  58 const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
  59
  60 /* start of interlace block in the y direction */
  61 const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
  62
  63 /* offset to next interlace block in the y direction */
  64 const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
  65
  66 /* width of interlace block (used in assembler routines only) */
  67 #ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
  68 const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
  69 #endif
  70
  71 /* Height of interlace block.  This is not currently used - if you need
  72  * it, uncomment it here and in png.h
  73 const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
  74 */
  75
  76 /* Mask to determine which pixels are valid in a pass */
  77 const int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
  78
  79 /* Mask to determine which pixels to overwrite while displaying */
  80 const int FARDATA png_pass_dsp_mask[]
  81    = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
  82
  83 #endif
  84
  85 /* Tells libpng that we have already handled the first "num_bytes" bytes
  86  * of the PNG file signature.  If the PNG data is embedded into another
  87  * stream we can set num_bytes = 8 so that libpng will not attempt to read
  88  * or write any of the magic bytes before it starts on the IHDR.
  89  */
  90
  91 void PNGAPI
  92 png_set_sig_bytes(png_structp png_ptr, int num_bytes)
  93 {
  94    png_debug(1, "in png_set_sig_bytes\n");
  95    if (num_bytes > 8)
  96       png_error(png_ptr, "Too many bytes for PNG signature.");
  97
  98    png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
  99 }
 100
 101 /* Checks whether the supplied bytes match the PNG signature.  We allow
 102  * checking less than the full 8-byte signature so that those apps that
 103  * already read the first few bytes of a file to determine the file type
 104  * can simply check the remaining bytes for extra assurance.  Returns
 105  * an integer less than, equal to, or greater than zero if sig is found,
 106  * respectively, to be less than, to match, or be greater than the correct
 107  * PNG signature (this is the same behaviour as strcmp, memcmp, etc).
 108  */
 109 int PNGAPI
 110 png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
 111 {
 112    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 113    if (num_to_check > 8)
 114       num_to_check = 8;
 115    else if (num_to_check < 1)
 116       return (0);
 117
 118    if (start > 7)
 119       return (0);
 120
 121    if (start + num_to_check > 8)
 122       num_to_check = 8 - start;
 123
 124    return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
 125 }
 126
 127 /* (Obsolete) function to check signature bytes.  It does not allow one
 128  * to check a partial signature.  This function might be removed in the
 129  * future - use png_sig_cmp().  Returns true (nonzero) if the file is a PNG.
 130  */
 131 int PNGAPI
 132 png_check_sig(png_bytep sig, int num)
 133 {
 134   return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
 135 }
 136
 137 /* Function to allocate memory for zlib and clear it to 0. */
 138 #ifdef PNG_1_0_X
 139 voidpf PNGAPI
 140 #else
 141 voidpf /* private */
 142 #endif
 143 png_zalloc(voidpf png_ptr, uInt items, uInt size)
 144 {
 145    png_voidp ptr;
 146    png_structp p=(png_struct*)png_ptr;
 147    png_uint_32 save_flags=p->flags;
 148    png_uint_32 num_bytes;
 149
 150    if (items > PNG_UINT_32_MAX/size)
 151    {
 152      png_warning (png_ptr, "Potential overflow in png_zalloc()");
 153      return (NULL);
 154    }
 155    num_bytes = (png_uint_32)items * size;
 156
 157    p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
 158    ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
 159    p->flags=save_flags;
 160
 161 #if defined(PNG_1_0_X) && !defined(PNG_NO_ZALLOC_ZERO)
 162    if (ptr == NULL)
 163        return ((voidpf)ptr);
 164
 165    if (num_bytes > (png_uint_32)0x8000L)
 166    {
 167       png_memset(ptr, 0, (png_size_t)0x8000L);
 168       png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,
 169          (png_size_t)(num_bytes - (png_uint_32)0x8000L));
 170    }
 171    else
 172    {
 173       png_memset(ptr, 0, (png_size_t)num_bytes);
 174    }
 175 #endif
 176    return ((voidpf)ptr);
 177 }
 178
 179 /* function to free memory for zlib */
 180 #ifdef PNG_1_0_X
 181 void PNGAPI
 182 #else
 183 void /* private */
 184 #endif
 185 png_zfree(voidpf png_ptr, voidpf ptr)
 186 {
 187    png_free((png_structp)png_ptr, (png_voidp)ptr);
 188 }
 189
 190 /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
 191  * in case CRC is > 32 bits to leave the top bits 0.
 192  */
 193 void /* PRIVATE */
 194 png_reset_crc(png_structp png_ptr)
 195 {
 196    png_ptr->crc = crc32(0, Z_NULL, 0);
 197 }
 198
 199 /* Calculate the CRC over a section of data.  We can only pass as
 200  * much data to this routine as the largest single buffer size.  We
 201  * also check that this data will actually be used before going to the
 202  * trouble of calculating it.
 203  */
 204 void /* PRIVATE */
 205 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
 206 {
 207    int need_crc = 1;
 208
 209    if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
 210    {
 211       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
 212           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
 213          need_crc = 0;
 214    }
 215    else                                                    /* critical */
 216    {
 217       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
 218          need_crc = 0;
 219    }
 220
 221    if (need_crc)
 222       png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
 223 }
 224
 225 /* Allocate the memory for an info_struct for the application.  We don't
 226  * really need the png_ptr, but it could potentially be useful in the
 227  * future.  This should be used in favour of malloc(png_sizeof(png_info))
 228  * and png_info_init() so that applications that want to use a shared
 229  * libpng don't have to be recompiled if png_info changes size.
 230  */
 231 png_infop PNGAPI
 232 png_create_info_struct(png_structp png_ptr)
 233 {
 234    png_infop info_ptr;
 235
 236    png_debug(1, "in png_create_info_struct\n");
 237    if(png_ptr == NULL) return (NULL);
 238 #ifdef PNG_USER_MEM_SUPPORTED
 239    info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
 240       png_ptr->malloc_fn, png_ptr->mem_ptr);
 241 #else
 242    info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 243 #endif
 244    if (info_ptr != NULL)
 245       png_info_init_3(&info_ptr, png_sizeof(png_info));
 246
 247    return (info_ptr);
 248 }
 249
 250 /* This function frees the memory associated with a single info struct.
 251  * Normally, one would use either png_destroy_read_struct() or
 252  * png_destroy_write_struct() to free an info struct, but this may be
 253  * useful for some applications.
 254  */
 255 void PNGAPI
 256 png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 257 {
 258    png_infop info_ptr = NULL;
 259
 260    png_debug(1, "in png_destroy_info_struct\n");
 261    if (info_ptr_ptr != NULL)
 262       info_ptr = *info_ptr_ptr;
 263
 264    if (info_ptr != NULL)
 265    {
 266       png_info_destroy(png_ptr, info_ptr);
 267
 268 #ifdef PNG_USER_MEM_SUPPORTED
 269       png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
 270           png_ptr->mem_ptr);
 271 #else
 272       png_destroy_struct((png_voidp)info_ptr);
 273 #endif
 274       *info_ptr_ptr = NULL;
 275    }
 276 }
 277
 278 /* Initialize the info structure.  This is now an internal function (0.89)
 279  * and applications using it are urged to use png_create_info_struct()
 280  * instead.
 281  */
 282 #undef png_info_init
 283 void PNGAPI
 284 png_info_init(png_infop info_ptr)
 285 {
 286    /* We only come here via pre-1.0.12-compiled applications */
 287    png_info_init_3(&info_ptr, 0);
 288 }
 289
 290 void PNGAPI
 291 png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
 292 {
 293    png_infop info_ptr = *ptr_ptr;
 294
 295    png_debug(1, "in png_info_init_3\n");
 296
 297    if(png_sizeof(png_info) > png_info_struct_size)
 298      {
 299        png_destroy_struct(info_ptr);
 300        info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 301        *ptr_ptr = info_ptr;
 302      }
 303
 304    /* set everything to 0 */
 305    png_memset(info_ptr, 0, png_sizeof (png_info));
 306 }
 307
 308 #ifdef PNG_FREE_ME_SUPPORTED
 309 void PNGAPI
 310 png_data_freer(png_structp png_ptr, png_infop info_ptr,
 311    int freer, png_uint_32 mask)
 312 {
 313    png_debug(1, "in png_data_freer\n");
 314    if (png_ptr == NULL || info_ptr == NULL)
 315       return;
 316    if(freer == PNG_DESTROY_WILL_FREE_DATA)
 317       info_ptr->free_me |= mask;
 318    else if(freer == PNG_USER_WILL_FREE_DATA)
 319       info_ptr->free_me &= ~mask;
 320    else
 321       png_warning(png_ptr,
 322          "Unknown freer parameter in png_data_freer.");
 323 }
 324 #endif
 325
 326 void PNGAPI
 327 png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 328    int num)
 329 {
 330    png_debug(1, "in png_free_data\n");
 331    if (png_ptr == NULL || info_ptr == NULL)
 332       return;
 333
 334 #if defined(PNG_TEXT_SUPPORTED)
 335 /* free text item num or (if num == -1) all text items */
 336 #ifdef PNG_FREE_ME_SUPPORTED
 337 if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
 338 #else
 339 if (mask & PNG_FREE_TEXT)
 340 #endif
 341 {
 342    if (num != -1)
 343    {
 344      if (info_ptr->text && info_ptr->text[num].key)
 345      {
 346          png_free(png_ptr, info_ptr->text[num].key);
 347          info_ptr->text[num].key = NULL;
 348      }
 349    }
 350    else
 351    {
 352        int i;
 353        for (i = 0; i < info_ptr->num_text; i++)
 354            png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
 355        png_free(png_ptr, info_ptr->text);
 356        info_ptr->text = NULL;
 357        info_ptr->num_text=0;
 358    }
 359 }
 360 #endif
 361
 362 #if defined(PNG_tRNS_SUPPORTED)
 363 /* free any tRNS entry */
 364 #ifdef PNG_FREE_ME_SUPPORTED
 365 if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
 366 #else
 367 if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))
 368 #endif
 369 {
 370     png_free(png_ptr, info_ptr->trans);
 371     info_ptr->valid &= ~PNG_INFO_tRNS;
 372 #ifndef PNG_FREE_ME_SUPPORTED
 373     png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
 374 #endif
 375     info_ptr->trans = NULL;
 376 }
 377 #endif
 378
 379 #if defined(PNG_sCAL_SUPPORTED)
 380 /* free any sCAL entry */
 381 #ifdef PNG_FREE_ME_SUPPORTED
 382 if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
 383 #else
 384 if (mask & PNG_FREE_SCAL)
 385 #endif
 386 {
 387 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
 388     png_free(png_ptr, info_ptr->scal_s_width);
 389     png_free(png_ptr, info_ptr->scal_s_height);
 390     info_ptr->scal_s_width = NULL;
 391     info_ptr->scal_s_height = NULL;
 392 #endif
 393     info_ptr->valid &= ~PNG_INFO_sCAL;
 394 }
 395 #endif
 396
 397 #if defined(PNG_pCAL_SUPPORTED)
 398 /* free any pCAL entry */
 399 #ifdef PNG_FREE_ME_SUPPORTED
 400 if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
 401 #else
 402 if (mask & PNG_FREE_PCAL)
 403 #endif
 404 {
 405     png_free(png_ptr, info_ptr->pcal_purpose);
 406     png_free(png_ptr, info_ptr->pcal_units);
 407     info_ptr->pcal_purpose = NULL;
 408     info_ptr->pcal_units = NULL;
 409     if (info_ptr->pcal_params != NULL)
 410     {
 411         int i;
 412         for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
 413         {
 414           png_free(png_ptr, info_ptr->pcal_params[i]);
 415           info_ptr->pcal_params[i]=NULL;
 416         }
 417         png_free(png_ptr, info_ptr->pcal_params);
 418         info_ptr->pcal_params = NULL;
 419     }
 420     info_ptr->valid &= ~PNG_INFO_pCAL;
 421 }
 422 #endif
 423
 424 #if defined(PNG_iCCP_SUPPORTED)
 425 /* free any iCCP entry */
 426 #ifdef PNG_FREE_ME_SUPPORTED
 427 if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
 428 #else
 429 if (mask & PNG_FREE_ICCP)
 430 #endif
 431 {
 432     png_free(png_ptr, info_ptr->iccp_name);
 433     png_free(png_ptr, info_ptr->iccp_profile);
 434     info_ptr->iccp_name = NULL;
 435     info_ptr->iccp_profile = NULL;
 436     info_ptr->valid &= ~PNG_INFO_iCCP;
 437 }
 438 #endif
 439
 440 #if defined(PNG_sPLT_SUPPORTED)
 441 /* free a given sPLT entry, or (if num == -1) all sPLT entries */
 442 #ifdef PNG_FREE_ME_SUPPORTED
 443 if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
 444 #else
 445 if (mask & PNG_FREE_SPLT)
 446 #endif
 447 {
 448    if (num != -1)
 449    {
 450       if(info_ptr->splt_palettes)
 451       {
 452           png_free(png_ptr, info_ptr->splt_palettes[num].name);
 453           png_free(png_ptr, info_ptr->splt_palettes[num].entries);
 454           info_ptr->splt_palettes[num].name = NULL;
 455           info_ptr->splt_palettes[num].entries = NULL;
 456       }
 457    }
 458    else
 459    {
 460        if(info_ptr->splt_palettes_num)
 461        {
 462          int i;
 463          for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
 464             png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
 465
 466          png_free(png_ptr, info_ptr->splt_palettes);
 467          info_ptr->splt_palettes = NULL;
 468          info_ptr->splt_palettes_num = 0;
 469        }
 470        info_ptr->valid &= ~PNG_INFO_sPLT;
 471    }
 472 }
 473 #endif
 474
 475 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 476 #ifdef PNG_FREE_ME_SUPPORTED
 477 if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
 478 #else
 479 if (mask & PNG_FREE_UNKN)
 480 #endif
 481 {
 482    if (num != -1)
 483    {
 484        if(info_ptr->unknown_chunks)
 485        {
 486           png_free(png_ptr, info_ptr->unknown_chunks[num].data);
 487           info_ptr->unknown_chunks[num].data = NULL;
 488        }
 489    }
 490    else
 491    {
 492        int i;
 493
 494        if(info_ptr->unknown_chunks_num)
 495        {
 496          for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
 497             png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
 498
 499          png_free(png_ptr, info_ptr->unknown_chunks);
 500          info_ptr->unknown_chunks = NULL;
 501          info_ptr->unknown_chunks_num = 0;
 502        }
 503    }
 504 }
 505 #endif
 506
 507 #if defined(PNG_hIST_SUPPORTED)
 508 /* free any hIST entry */
 509 #ifdef PNG_FREE_ME_SUPPORTED
 510 if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
 511 #else
 512 if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
 513 #endif
 514 {
 515     png_free(png_ptr, info_ptr->hist);
 516     info_ptr->hist = NULL;
 517     info_ptr->valid &= ~PNG_INFO_hIST;
 518 #ifndef PNG_FREE_ME_SUPPORTED
 519     png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
 520 #endif
 521 }
 522 #endif
 523
 524 /* free any PLTE entry that was internally allocated */
 525 #ifdef PNG_FREE_ME_SUPPORTED
 526 if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
 527 #else
 528 if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
 529 #endif
 530 {
 531     png_zfree(png_ptr, info_ptr->palette);
 532     info_ptr->palette = NULL;
 533     info_ptr->valid &= ~PNG_INFO_PLTE;
 534 #ifndef PNG_FREE_ME_SUPPORTED
 535     png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
 536 #endif
 537     info_ptr->num_palette = 0;
 538 }
 539
 540 #if defined(PNG_INFO_IMAGE_SUPPORTED)
 541 /* free any image bits attached to the info structure */
 542 #ifdef PNG_FREE_ME_SUPPORTED
 543 if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
 544 #else
 545 if (mask & PNG_FREE_ROWS)
 546 #endif
 547 {
 548     if(info_ptr->row_pointers)
 549     {
 550        int row;
 551        for (row = 0; row < (int)info_ptr->height; row++)
 552        {
 553           png_free(png_ptr, info_ptr->row_pointers[row]);
 554           info_ptr->row_pointers[row]=NULL;
 555        }
 556        png_free(png_ptr, info_ptr->row_pointers);
 557        info_ptr->row_pointers=NULL;
 558     }
 559     info_ptr->valid &= ~PNG_INFO_IDAT;
 560 }
 561 #endif
 562
 563 #ifdef PNG_FREE_ME_SUPPORTED
 564    if(num == -1)
 565      info_ptr->free_me &= ~mask;
 566    else
 567      info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
 568 #endif
 569 }
 570
 571 /* This is an internal routine to free any memory that the info struct is
 572  * pointing to before re-using it or freeing the struct itself.  Recall
 573  * that png_free() checks for NULL pointers for us.
 574  */
 575 void /* PRIVATE */
 576 png_info_destroy(png_structp png_ptr, png_infop info_ptr)
 577 {
 578    png_debug(1, "in png_info_destroy\n");
 579
 580    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 581
 582 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 583    if (png_ptr->num_chunk_list)
 584    {
 585        png_free(png_ptr, png_ptr->chunk_list);
 586        png_ptr->chunk_list=NULL;
 587        png_ptr->num_chunk_list=0;
 588    }
 589 #endif
 590
 591    png_info_init_3(&info_ptr, png_sizeof(png_info));
 592 }
 593
 594 /* This function returns a pointer to the io_ptr associated with the user
 595  * functions.  The application should free any memory associated with this
 596  * pointer before png_write_destroy() or png_read_destroy() are called.
 597  */
 598 png_voidp PNGAPI
 599 png_get_io_ptr(png_structp png_ptr)
 600 {
 601    return (png_ptr->io_ptr);
 602 }
 603
 604 #if !defined(PNG_NO_STDIO)
 605 /* Initialize the default input/output functions for the PNG file.  If you
 606  * use your own read or write routines, you can call either png_set_read_fn()
 607  * or png_set_write_fn() instead of png_init_io().  If you have defined
 608  * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
 609  * necessarily available.
 610  */
 611 void PNGAPI
 612 png_init_io(png_structp png_ptr, png_FILE_p fp)
 613 {
 614    png_debug(1, "in png_init_io\n");
 615    png_ptr->io_ptr = (png_voidp)fp;
 616 }
 617 #endif
 618
 619 #if defined(PNG_TIME_RFC1123_SUPPORTED)
 620 /* Convert the supplied time into an RFC 1123 string suitable for use in
 621  * a "Creation Time" or other text-based time string.
 622  */
 623 png_charp PNGAPI
 624 png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 625 {
 626    static PNG_CONST char short_months[12][4] =
 627         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 628          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 629
 630    if (png_ptr->time_buffer == NULL)
 631    {
 632       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
 633          png_sizeof(char)));
 634    }
 635
 636 #if defined(_WIN32_WCE)
 637    {
 638       wchar_t time_buf[29];
 639       wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
 640           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 641         ptime->year, ptime->hour % 24, ptime->minute % 60,
 642           ptime->second % 61);
 643       WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,
 644           NULL, NULL);
 645    }
 646 #else
 647 #ifdef USE_FAR_KEYWORD
 648    {
 649       char near_time_buf[29];
 650       sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
 651           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 652           ptime->year, ptime->hour % 24, ptime->minute % 60,
 653           ptime->second % 61);
 654       png_memcpy(png_ptr->time_buffer, near_time_buf,
 655           29*png_sizeof(char));
 656    }
 657 #else
 658    sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
 659        ptime->day % 32, short_months[(ptime->month - 1) % 12],
 660        ptime->year, ptime->hour % 24, ptime->minute % 60,
 661        ptime->second % 61);
 662 #endif
 663 #endif /* _WIN32_WCE */
 664    return ((png_charp)png_ptr->time_buffer);
 665 }
 666 #endif /* PNG_TIME_RFC1123_SUPPORTED */
 667
 668 #if 0
 669 /* Signature string for a PNG file. */
 670 png_bytep PNGAPI
 671 png_sig_bytes(void)
 672 {
 673    return ((png_bytep)"\211\120\116\107\015\012\032\012");
 674 }
 675 #endif
 676
 677 png_charp PNGAPI
 678 png_get_copyright(png_structp png_ptr)
 679 {
 680    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 681    return ((png_charp) "\n libpng version 1.2.6 - August 15, 2004\n\
 682    Copyright (c) 1998-2004 Glenn Randers-Pehrson\n\
 683    Copyright (c) 1996-1997 Andreas Dilger\n\
 684    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
 685    return ((png_charp) "");
 686 }
 687
 688 /* The following return the library version as a short string in the
 689  * format 1.0.0 through 99.99.99zz.  To get the version of *.h files
 690  * used with your application, print out PNG_LIBPNG_VER_STRING, which
 691  * is defined in png.h.
 692  * Note: now there is no difference between png_get_libpng_ver() and
 693  * png_get_header_ver().  Due to the version_nn_nn_nn typedef guard,
 694  * it is guaranteed that png.c uses the correct version of png.h.
 695  */
 696 png_charp PNGAPI
 697 png_get_libpng_ver(png_structp png_ptr)
 698 {
 699    /* Version of *.c files used when building libpng */
 700    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 701       return ((png_charp) PNG_LIBPNG_VER_STRING);
 702    return ((png_charp) "");
 703 }
 704
 705 png_charp PNGAPI
 706 png_get_header_ver(png_structp png_ptr)
 707 {
 708    /* Version of *.h files used when building libpng */
 709    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 710       return ((png_charp) PNG_LIBPNG_VER_STRING);
 711    return ((png_charp) "");
 712 }
 713
 714 png_charp PNGAPI
 715 png_get_header_version(png_structp png_ptr)
 716 {
 717    /* Returns longer string containing both version and date */
 718    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 719       return ((png_charp) PNG_HEADER_VERSION_STRING);
 720    return ((png_charp) "");
 721 }
 722
 723 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 724 int PNGAPI
 725 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 726 {
 727    /* check chunk_name and return "keep" value if it's on the list, else 0 */
 728    int i;
 729    png_bytep p;
 730    if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0)
 731       return 0;
 732    p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5;
 733    for (i = png_ptr->num_chunk_list; i; i--, p-=5)
 734       if (!png_memcmp(chunk_name, p, 4))
 735         return ((int)*(p+4));
 736    return 0;
 737 }
 738 #endif
 739
 740 /* This function, added to libpng-1.0.6g, is untested. */
 741 int PNGAPI
 742 png_reset_zstream(png_structp png_ptr)
 743 {
 744    return (inflateReset(&png_ptr->zstream));
 745 }
 746
 747 /* This function was added to libpng-1.0.7 */
 748 png_uint_32 PNGAPI
 749 png_access_version_number(void)
 750 {
 751    /* Version of *.c files used when building libpng */
 752    return((png_uint_32) PNG_LIBPNG_VER);
 753 }
 754
 755
 756 #if !defined(PNG_1_0_X)
 757 #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
 758     /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
 759 /* this INTERNAL function was added to libpng 1.2.0 */
 760 void /* PRIVATE */
 761 png_init_mmx_flags (png_structp png_ptr)
 762 {
 763     png_ptr->mmx_rowbytes_threshold = 0;
 764     png_ptr->mmx_bitdepth_threshold = 0;
 765
 766 #  if (defined(PNG_USE_PNGVCRD) || defined(PNG_USE_PNGGCCRD))
 767
 768     png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_COMPILED;
 769
 770     if (png_mmx_support() > 0) {
 771         png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
 772 #    ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
 773                               | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
 774 #    endif
 775 #    ifdef PNG_HAVE_ASSEMBLER_READ_INTERLACE
 776                               | PNG_ASM_FLAG_MMX_READ_INTERLACE
 777 #    endif
 778 #    ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
 779                               ;
 780 #    else
 781                               | PNG_ASM_FLAG_MMX_READ_FILTER_SUB
 782                               | PNG_ASM_FLAG_MMX_READ_FILTER_UP
 783                               | PNG_ASM_FLAG_MMX_READ_FILTER_AVG
 784                               | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
 785
 786         png_ptr->mmx_rowbytes_threshold = PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT;
 787         png_ptr->mmx_bitdepth_threshold = PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT;
 788 #    endif
 789     } else {
 790         png_ptr->asm_flags &= ~( PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
 791                                | PNG_MMX_READ_FLAGS
 792                                | PNG_MMX_WRITE_FLAGS );
 793     }
 794
 795 #  else /* !((PNGVCRD || PNGGCCRD) && PNG_ASSEMBLER_CODE_SUPPORTED)) */
 796
 797     /* clear all MMX flags; no support is compiled in */
 798     png_ptr->asm_flags &= ~( PNG_MMX_FLAGS );
 799
 800 #  endif /* ?(PNGVCRD || PNGGCCRD) */
 801 }
 802
 803 #endif /* !(PNG_ASSEMBLER_CODE_SUPPORTED) */
 804
 805 /* this function was added to libpng 1.2.0 */
 806 #if !defined(PNG_USE_PNGGCCRD) && \
 807     !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD))
 808 int PNGAPI
 809 png_mmx_support(void)
 810 {
 811     return -1;
 812 }
 813 #endif
 814 #endif /* PNG_1_0_X */
 815
 816 #ifdef PNG_SIZE_T
 817 /* Added at libpng version 1.2.6 */
 818    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
 819 png_size_t PNGAPI
 820 png_convert_size(size_t size)
 821 {
 822   if (size > (png_size_t)-1)
 823      PNG_ABORT();  /* We haven't got access to png_ptr, so no png_error() */
 824   return ((png_size_t)size);
 825 }
 826 #endif /* PNG_SIZE_T */