com32/lib/libpng/png.c

   1
   2 /* png.c - location for general purpose libpng functions
   3  *
   4  * libpng version 1.2.8 - December 3, 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_8 Your_png_h_is_not_version_1_2_8;
  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 /* PNG_USE_GLOBAL_ARRAYS */
  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_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 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 283 #undef png_info_init
 284 void PNGAPI
 285 png_info_init(png_infop info_ptr)
 286 {
 287    /* We only come here via pre-1.0.12-compiled applications */
 288    png_info_init_3(&info_ptr, 0);
 289 }
 290 #endif
 291
 292 void PNGAPI
 293 png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
 294 {
 295    png_infop info_ptr = *ptr_ptr;
 296
 297    png_debug(1, "in png_info_init_3\n");
 298
 299    if(png_sizeof(png_info) > png_info_struct_size)
 300      {
 301        png_destroy_struct(info_ptr);
 302        info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 303        *ptr_ptr = info_ptr;
 304      }
 305
 306    /* set everything to 0 */
 307    png_memset(info_ptr, 0, png_sizeof (png_info));
 308 }
 309
 310 #ifdef PNG_FREE_ME_SUPPORTED
 311 void PNGAPI
 312 png_data_freer(png_structp png_ptr, png_infop info_ptr,
 313    int freer, png_uint_32 mask)
 314 {
 315    png_debug(1, "in png_data_freer\n");
 316    if (png_ptr == NULL || info_ptr == NULL)
 317       return;
 318    if(freer == PNG_DESTROY_WILL_FREE_DATA)
 319       info_ptr->free_me |= mask;
 320    else if(freer == PNG_USER_WILL_FREE_DATA)
 321       info_ptr->free_me &= ~mask;
 322    else
 323       png_warning(png_ptr,
 324          "Unknown freer parameter in png_data_freer.");
 325 }
 326 #endif
 327
 328 void PNGAPI
 329 png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 330    int num)
 331 {
 332    png_debug(1, "in png_free_data\n");
 333    if (png_ptr == NULL || info_ptr == NULL)
 334       return;
 335
 336 #if defined(PNG_TEXT_SUPPORTED)
 337 /* free text item num or (if num == -1) all text items */
 338 #ifdef PNG_FREE_ME_SUPPORTED
 339 if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
 340 #else
 341 if (mask & PNG_FREE_TEXT)
 342 #endif
 343 {
 344    if (num != -1)
 345    {
 346      if (info_ptr->text && info_ptr->text[num].key)
 347      {
 348          png_free(png_ptr, info_ptr->text[num].key);
 349          info_ptr->text[num].key = NULL;
 350      }
 351    }
 352    else
 353    {
 354        int i;
 355        for (i = 0; i < info_ptr->num_text; i++)
 356            png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
 357        png_free(png_ptr, info_ptr->text);
 358        info_ptr->text = NULL;
 359        info_ptr->num_text=0;
 360    }
 361 }
 362 #endif
 363
 364 #if defined(PNG_tRNS_SUPPORTED)
 365 /* free any tRNS entry */
 366 #ifdef PNG_FREE_ME_SUPPORTED
 367 if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
 368 #else
 369 if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))
 370 #endif
 371 {
 372     png_free(png_ptr, info_ptr->trans);
 373     info_ptr->valid &= ~PNG_INFO_tRNS;
 374 #ifndef PNG_FREE_ME_SUPPORTED
 375     png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
 376 #endif
 377     info_ptr->trans = NULL;
 378 }
 379 #endif
 380
 381 #if defined(PNG_sCAL_SUPPORTED)
 382 /* free any sCAL entry */
 383 #ifdef PNG_FREE_ME_SUPPORTED
 384 if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
 385 #else
 386 if (mask & PNG_FREE_SCAL)
 387 #endif
 388 {
 389 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
 390     png_free(png_ptr, info_ptr->scal_s_width);
 391     png_free(png_ptr, info_ptr->scal_s_height);
 392     info_ptr->scal_s_width = NULL;
 393     info_ptr->scal_s_height = NULL;
 394 #endif
 395     info_ptr->valid &= ~PNG_INFO_sCAL;
 396 }
 397 #endif
 398
 399 #if defined(PNG_pCAL_SUPPORTED)
 400 /* free any pCAL entry */
 401 #ifdef PNG_FREE_ME_SUPPORTED
 402 if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
 403 #else
 404 if (mask & PNG_FREE_PCAL)
 405 #endif
 406 {
 407     png_free(png_ptr, info_ptr->pcal_purpose);
 408     png_free(png_ptr, info_ptr->pcal_units);
 409     info_ptr->pcal_purpose = NULL;
 410     info_ptr->pcal_units = NULL;
 411     if (info_ptr->pcal_params != NULL)
 412     {
 413         int i;
 414         for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
 415         {
 416           png_free(png_ptr, info_ptr->pcal_params[i]);
 417           info_ptr->pcal_params[i]=NULL;
 418         }
 419         png_free(png_ptr, info_ptr->pcal_params);
 420         info_ptr->pcal_params = NULL;
 421     }
 422     info_ptr->valid &= ~PNG_INFO_pCAL;
 423 }
 424 #endif
 425
 426 #if defined(PNG_iCCP_SUPPORTED)
 427 /* free any iCCP entry */
 428 #ifdef PNG_FREE_ME_SUPPORTED
 429 if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
 430 #else
 431 if (mask & PNG_FREE_ICCP)
 432 #endif
 433 {
 434     png_free(png_ptr, info_ptr->iccp_name);
 435     png_free(png_ptr, info_ptr->iccp_profile);
 436     info_ptr->iccp_name = NULL;
 437     info_ptr->iccp_profile = NULL;
 438     info_ptr->valid &= ~PNG_INFO_iCCP;
 439 }
 440 #endif
 441
 442 #if defined(PNG_sPLT_SUPPORTED)
 443 /* free a given sPLT entry, or (if num == -1) all sPLT entries */
 444 #ifdef PNG_FREE_ME_SUPPORTED
 445 if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
 446 #else
 447 if (mask & PNG_FREE_SPLT)
 448 #endif
 449 {
 450    if (num != -1)
 451    {
 452       if(info_ptr->splt_palettes)
 453       {
 454           png_free(png_ptr, info_ptr->splt_palettes[num].name);
 455           png_free(png_ptr, info_ptr->splt_palettes[num].entries);
 456           info_ptr->splt_palettes[num].name = NULL;
 457           info_ptr->splt_palettes[num].entries = NULL;
 458       }
 459    }
 460    else
 461    {
 462        if(info_ptr->splt_palettes_num)
 463        {
 464          int i;
 465          for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
 466             png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
 467
 468          png_free(png_ptr, info_ptr->splt_palettes);
 469          info_ptr->splt_palettes = NULL;
 470          info_ptr->splt_palettes_num = 0;
 471        }
 472        info_ptr->valid &= ~PNG_INFO_sPLT;
 473    }
 474 }
 475 #endif
 476
 477 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 478 #ifdef PNG_FREE_ME_SUPPORTED
 479 if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
 480 #else
 481 if (mask & PNG_FREE_UNKN)
 482 #endif
 483 {
 484    if (num != -1)
 485    {
 486        if(info_ptr->unknown_chunks)
 487        {
 488           png_free(png_ptr, info_ptr->unknown_chunks[num].data);
 489           info_ptr->unknown_chunks[num].data = NULL;
 490        }
 491    }
 492    else
 493    {
 494        int i;
 495
 496        if(info_ptr->unknown_chunks_num)
 497        {
 498          for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
 499             png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
 500
 501          png_free(png_ptr, info_ptr->unknown_chunks);
 502          info_ptr->unknown_chunks = NULL;
 503          info_ptr->unknown_chunks_num = 0;
 504        }
 505    }
 506 }
 507 #endif
 508
 509 #if defined(PNG_hIST_SUPPORTED)
 510 /* free any hIST entry */
 511 #ifdef PNG_FREE_ME_SUPPORTED
 512 if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
 513 #else
 514 if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
 515 #endif
 516 {
 517     png_free(png_ptr, info_ptr->hist);
 518     info_ptr->hist = NULL;
 519     info_ptr->valid &= ~PNG_INFO_hIST;
 520 #ifndef PNG_FREE_ME_SUPPORTED
 521     png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
 522 #endif
 523 }
 524 #endif
 525
 526 /* free any PLTE entry that was internally allocated */
 527 #ifdef PNG_FREE_ME_SUPPORTED
 528 if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
 529 #else
 530 if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
 531 #endif
 532 {
 533     png_zfree(png_ptr, info_ptr->palette);
 534     info_ptr->palette = NULL;
 535     info_ptr->valid &= ~PNG_INFO_PLTE;
 536 #ifndef PNG_FREE_ME_SUPPORTED
 537     png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
 538 #endif
 539     info_ptr->num_palette = 0;
 540 }
 541
 542 #if defined(PNG_INFO_IMAGE_SUPPORTED)
 543 /* free any image bits attached to the info structure */
 544 #ifdef PNG_FREE_ME_SUPPORTED
 545 if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
 546 #else
 547 if (mask & PNG_FREE_ROWS)
 548 #endif
 549 {
 550     if(info_ptr->row_pointers)
 551     {
 552        int row;
 553        for (row = 0; row < (int)info_ptr->height; row++)
 554        {
 555           png_free(png_ptr, info_ptr->row_pointers[row]);
 556           info_ptr->row_pointers[row]=NULL;
 557        }
 558        png_free(png_ptr, info_ptr->row_pointers);
 559        info_ptr->row_pointers=NULL;
 560     }
 561     info_ptr->valid &= ~PNG_INFO_IDAT;
 562 }
 563 #endif
 564
 565 #ifdef PNG_FREE_ME_SUPPORTED
 566    if(num == -1)
 567      info_ptr->free_me &= ~mask;
 568    else
 569      info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
 570 #endif
 571 }
 572
 573 /* This is an internal routine to free any memory that the info struct is
 574  * pointing to before re-using it or freeing the struct itself.  Recall
 575  * that png_free() checks for NULL pointers for us.
 576  */
 577 void /* PRIVATE */
 578 png_info_destroy(png_structp png_ptr, png_infop info_ptr)
 579 {
 580    png_debug(1, "in png_info_destroy\n");
 581
 582    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 583
 584 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 585    if (png_ptr->num_chunk_list)
 586    {
 587        png_free(png_ptr, png_ptr->chunk_list);
 588        png_ptr->chunk_list=NULL;
 589        png_ptr->num_chunk_list=0;
 590    }
 591 #endif
 592
 593    png_info_init_3(&info_ptr, png_sizeof(png_info));
 594 }
 595
 596 /* This function returns a pointer to the io_ptr associated with the user
 597  * functions.  The application should free any memory associated with this
 598  * pointer before png_write_destroy() or png_read_destroy() are called.
 599  */
 600 png_voidp PNGAPI
 601 png_get_io_ptr(png_structp png_ptr)
 602 {
 603    return (png_ptr->io_ptr);
 604 }
 605
 606 #if !defined(PNG_NO_STDIO)
 607 /* Initialize the default input/output functions for the PNG file.  If you
 608  * use your own read or write routines, you can call either png_set_read_fn()
 609  * or png_set_write_fn() instead of png_init_io().  If you have defined
 610  * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
 611  * necessarily available.
 612  */
 613 void PNGAPI
 614 png_init_io(png_structp png_ptr, png_FILE_p fp)
 615 {
 616    png_debug(1, "in png_init_io\n");
 617    png_ptr->io_ptr = (png_voidp)fp;
 618 }
 619 #endif
 620
 621 #if defined(PNG_TIME_RFC1123_SUPPORTED)
 622 /* Convert the supplied time into an RFC 1123 string suitable for use in
 623  * a "Creation Time" or other text-based time string.
 624  */
 625 png_charp PNGAPI
 626 png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 627 {
 628    static PNG_CONST char short_months[12][4] =
 629         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 630          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 631
 632    if (png_ptr->time_buffer == NULL)
 633    {
 634       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
 635          png_sizeof(char)));
 636    }
 637
 638 #if defined(_WIN32_WCE)
 639    {
 640       wchar_t time_buf[29];
 641       wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
 642           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 643         ptime->year, ptime->hour % 24, ptime->minute % 60,
 644           ptime->second % 61);
 645       WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,
 646           NULL, NULL);
 647    }
 648 #else
 649 #ifdef USE_FAR_KEYWORD
 650    {
 651       char near_time_buf[29];
 652       sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
 653           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 654           ptime->year, ptime->hour % 24, ptime->minute % 60,
 655           ptime->second % 61);
 656       png_memcpy(png_ptr->time_buffer, near_time_buf,
 657           29*png_sizeof(char));
 658    }
 659 #else
 660    sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
 661        ptime->day % 32, short_months[(ptime->month - 1) % 12],
 662        ptime->year, ptime->hour % 24, ptime->minute % 60,
 663        ptime->second % 61);
 664 #endif
 665 #endif /* _WIN32_WCE */
 666    return ((png_charp)png_ptr->time_buffer);
 667 }
 668 #endif /* PNG_TIME_RFC1123_SUPPORTED */
 669
 670 #if 0
 671 /* Signature string for a PNG file. */
 672 png_bytep PNGAPI
 673 png_sig_bytes(void)
 674 {
 675    return ((png_bytep)"\211\120\116\107\015\012\032\012");
 676 }
 677 #endif
 678
 679 png_charp PNGAPI
 680 png_get_copyright(png_structp png_ptr)
 681 {
 682    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 683    return ((png_charp) "\n libpng version 1.2.8 - December 3, 2004\n\
 684    Copyright (c) 1998-2004 Glenn Randers-Pehrson\n\
 685    Copyright (c) 1996-1997 Andreas Dilger\n\
 686    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
 687    return ((png_charp) "");
 688 }
 689
 690 /* The following return the library version as a short string in the
 691  * format 1.0.0 through 99.99.99zz.  To get the version of *.h files
 692  * used with your application, print out PNG_LIBPNG_VER_STRING, which
 693  * is defined in png.h.
 694  * Note: now there is no difference between png_get_libpng_ver() and
 695  * png_get_header_ver().  Due to the version_nn_nn_nn typedef guard,
 696  * it is guaranteed that png.c uses the correct version of png.h.
 697  */
 698 png_charp PNGAPI
 699 png_get_libpng_ver(png_structp png_ptr)
 700 {
 701    /* Version of *.c files used when building libpng */
 702    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 703       return ((png_charp) PNG_LIBPNG_VER_STRING);
 704    return ((png_charp) "");
 705 }
 706
 707 png_charp PNGAPI
 708 png_get_header_ver(png_structp png_ptr)
 709 {
 710    /* Version of *.h files used when building libpng */
 711    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 712       return ((png_charp) PNG_LIBPNG_VER_STRING);
 713    return ((png_charp) "");
 714 }
 715
 716 png_charp PNGAPI
 717 png_get_header_version(png_structp png_ptr)
 718 {
 719    /* Returns longer string containing both version and date */
 720    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
 721       return ((png_charp) PNG_HEADER_VERSION_STRING);
 722    return ((png_charp) "");
 723 }
 724
 725 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 726 int PNGAPI
 727 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 728 {
 729    /* check chunk_name and return "keep" value if it's on the list, else 0 */
 730    int i;
 731    png_bytep p;
 732    if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0)
 733       return 0;
 734    p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5;
 735    for (i = png_ptr->num_chunk_list; i; i--, p-=5)
 736       if (!png_memcmp(chunk_name, p, 4))
 737         return ((int)*(p+4));
 738    return 0;
 739 }
 740 #endif
 741
 742 /* This function, added to libpng-1.0.6g, is untested. */
 743 int PNGAPI
 744 png_reset_zstream(png_structp png_ptr)
 745 {
 746    return (inflateReset(&png_ptr->zstream));
 747 }
 748
 749 /* This function was added to libpng-1.0.7 */
 750 png_uint_32 PNGAPI
 751 png_access_version_number(void)
 752 {
 753    /* Version of *.c files used when building libpng */
 754    return((png_uint_32) PNG_LIBPNG_VER);
 755 }
 756
 757
 758 #if !defined(PNG_1_0_X)
 759 #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
 760     /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
 761 /* this INTERNAL function was added to libpng 1.2.0 */
 762 void /* PRIVATE */
 763 png_init_mmx_flags (png_structp png_ptr)
 764 {
 765     png_ptr->mmx_rowbytes_threshold = 0;
 766     png_ptr->mmx_bitdepth_threshold = 0;
 767
 768 #  if (defined(PNG_USE_PNGVCRD) || defined(PNG_USE_PNGGCCRD))
 769
 770     png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_COMPILED;
 771
 772     if (png_mmx_support() > 0) {
 773         png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
 774 #    ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
 775                               | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
 776 #    endif
 777 #    ifdef PNG_HAVE_ASSEMBLER_READ_INTERLACE
 778                               | PNG_ASM_FLAG_MMX_READ_INTERLACE
 779 #    endif
 780 #    ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
 781                               ;
 782 #    else
 783                               | PNG_ASM_FLAG_MMX_READ_FILTER_SUB
 784                               | PNG_ASM_FLAG_MMX_READ_FILTER_UP
 785                               | PNG_ASM_FLAG_MMX_READ_FILTER_AVG
 786                               | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
 787
 788         png_ptr->mmx_rowbytes_threshold = PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT;
 789         png_ptr->mmx_bitdepth_threshold = PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT;
 790 #    endif
 791     } else {
 792         png_ptr->asm_flags &= ~( PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
 793                                | PNG_MMX_READ_FLAGS
 794                                | PNG_MMX_WRITE_FLAGS );
 795     }
 796
 797 #  else /* !((PNGVCRD || PNGGCCRD) && PNG_ASSEMBLER_CODE_SUPPORTED)) */
 798
 799     /* clear all MMX flags; no support is compiled in */
 800     png_ptr->asm_flags &= ~( PNG_MMX_FLAGS );
 801
 802 #  endif /* ?(PNGVCRD || PNGGCCRD) */
 803 }
 804
 805 #endif /* !(PNG_ASSEMBLER_CODE_SUPPORTED) */
 806
 807 /* this function was added to libpng 1.2.0 */
 808 #if !defined(PNG_USE_PNGGCCRD) && \
 809     !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD))
 810 int PNGAPI
 811 png_mmx_support(void)
 812 {
 813     return -1;
 814 }
 815 #endif
 816 #endif /* PNG_1_0_X */
 817
 818 #ifdef PNG_SIZE_T
 819 /* Added at libpng version 1.2.6 */
 820    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
 821 png_size_t PNGAPI
 822 png_convert_size(size_t size)
 823 {
 824   if (size > (png_size_t)-1)
 825      PNG_ABORT();  /* We haven't got access to png_ptr, so no png_error() */
 826   return ((png_size_t)size);
 827 }
 828 #endif /* PNG_SIZE_T */