src/png/png.c

   1
   2 /* png.c - location for general purpose libpng functions
   3  *
   4  * Last changed in libpng 1.2.34 [December 18, 2008]
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1998-2008 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_34 Your_png_h_is_not_version_1_2_34;
  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 PNG_CONST char png_libpng_ver[18] = PNG_LIBPNG_VER_STRING;
  24
  25 #ifdef PNG_READ_SUPPORTED
  26
  27 /* png_sig was changed to a function in version 1.0.5c */
  28 /* Place to hold the signature string for a PNG file. */
  29 PNG_CONST png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
  30 #endif /* PNG_READ_SUPPORTED */
  31
  32 /* Invoke global declarations for constant strings for known chunk types */
  33 PNG_IHDR;
  34 PNG_IDAT;
  35 PNG_IEND;
  36 PNG_PLTE;
  37 PNG_bKGD;
  38 PNG_cHRM;
  39 PNG_gAMA;
  40 PNG_hIST;
  41 PNG_iCCP;
  42 PNG_iTXt;
  43 PNG_oFFs;
  44 PNG_pCAL;
  45 PNG_sCAL;
  46 PNG_pHYs;
  47 PNG_sBIT;
  48 PNG_sPLT;
  49 PNG_sRGB;
  50 PNG_tEXt;
  51 PNG_tIME;
  52 PNG_tRNS;
  53 PNG_zTXt;
  54
  55 #ifdef PNG_READ_SUPPORTED
  56 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
  57
  58 /* start of interlace block */
  59 PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
  60
  61 /* offset to next interlace block */
  62 PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
  63
  64 /* start of interlace block in the y direction */
  65 PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
  66
  67 /* offset to next interlace block in the y direction */
  68 PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
  69
  70 /* Height of interlace block.  This is not currently used - if you need
  71  * it, uncomment it here and in png.h
  72 PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
  73 */
  74
  75 /* Mask to determine which pixels are valid in a pass */
  76 PNG_CONST int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
  77
  78 /* Mask to determine which pixels to overwrite while displaying */
  79 PNG_CONST int FARDATA png_pass_dsp_mask[]
  80    = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
  81
  82 #endif /* PNG_READ_SUPPORTED */
  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 #ifdef PNG_READ_SUPPORTED
  92 void PNGAPI
  93 png_set_sig_bytes(png_structp png_ptr, int num_bytes)
  94 {
  95    if (png_ptr == NULL) return;
  96    png_debug(1, "in png_set_sig_bytes");
  97    if (num_bytes > 8)
  98       png_error(png_ptr, "Too many bytes for PNG signature.");
  99
 100    png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
 101 }
 102
 103 /* Checks whether the supplied bytes match the PNG signature.  We allow
 104  * checking less than the full 8-byte signature so that those apps that
 105  * already read the first few bytes of a file to determine the file type
 106  * can simply check the remaining bytes for extra assurance.  Returns
 107  * an integer less than, equal to, or greater than zero if sig is found,
 108  * respectively, to be less than, to match, or be greater than the correct
 109  * PNG signature (this is the same behaviour as strcmp, memcmp, etc).
 110  */
 111 int PNGAPI
 112 png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
 113 {
 114    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 115    if (num_to_check > 8)
 116       num_to_check = 8;
 117    else if (num_to_check < 1)
 118       return (-1);
 119
 120    if (start > 7)
 121       return (-1);
 122
 123    if (start + num_to_check > 8)
 124       num_to_check = 8 - start;
 125
 126    return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
 127 }
 128
 129 #if defined(PNG_1_0_X) || defined(PNG_1_2_X)
 130 /* (Obsolete) function to check signature bytes.  It does not allow one
 131  * to check a partial signature.  This function might be removed in the
 132  * future - use png_sig_cmp().  Returns true (nonzero) if the file is PNG.
 133  */
 134 int PNGAPI
 135 png_check_sig(png_bytep sig, int num)
 136 {
 137   return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
 138 }
 139 #endif
 140 #endif /* PNG_READ_SUPPORTED */
 141
 142 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 143 /* Function to allocate memory for zlib and clear it to 0. */
 144 #ifdef PNG_1_0_X
 145 voidpf PNGAPI
 146 #else
 147 voidpf /* private */
 148 #endif
 149 png_zalloc(voidpf png_ptr, uInt items, uInt size)
 150 {
 151    png_voidp ptr;
 152    png_structp p=(png_structp)png_ptr;
 153    png_uint_32 save_flags=p->flags;
 154    png_uint_32 num_bytes;
 155
 156    if (png_ptr == NULL) return (NULL);
 157    if (items > PNG_UINT_32_MAX/size)
 158    {
 159      png_warning (p, "Potential overflow in png_zalloc()");
 160      return (NULL);
 161    }
 162    num_bytes = (png_uint_32)items * size;
 163
 164    p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
 165    ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
 166    p->flags=save_flags;
 167
 168 #if defined(PNG_1_0_X) && !defined(PNG_NO_ZALLOC_ZERO)
 169    if (ptr == NULL)
 170        return ((voidpf)ptr);
 171
 172    if (num_bytes > (png_uint_32)0x8000L)
 173    {
 174       png_memset(ptr, 0, (png_size_t)0x8000L);
 175       png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,
 176          (png_size_t)(num_bytes - (png_uint_32)0x8000L));
 177    }
 178    else
 179    {
 180       png_memset(ptr, 0, (png_size_t)num_bytes);
 181    }
 182 #endif
 183    return ((voidpf)ptr);
 184 }
 185
 186 /* function to free memory for zlib */
 187 #ifdef PNG_1_0_X
 188 void PNGAPI
 189 #else
 190 void /* private */
 191 #endif
 192 png_zfree(voidpf png_ptr, voidpf ptr)
 193 {
 194    png_free((png_structp)png_ptr, (png_voidp)ptr);
 195 }
 196
 197 /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
 198  * in case CRC is > 32 bits to leave the top bits 0.
 199  */
 200 void /* PRIVATE */
 201 png_reset_crc(png_structp png_ptr)
 202 {
 203    png_ptr->crc = crc32(0, Z_NULL, 0);
 204 }
 205
 206 /* Calculate the CRC over a section of data.  We can only pass as
 207  * much data to this routine as the largest single buffer size.  We
 208  * also check that this data will actually be used before going to the
 209  * trouble of calculating it.
 210  */
 211 void /* PRIVATE */
 212 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
 213 {
 214    int need_crc = 1;
 215
 216    if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
 217    {
 218       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
 219           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
 220          need_crc = 0;
 221    }
 222    else                                                    /* critical */
 223    {
 224       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
 225          need_crc = 0;
 226    }
 227
 228    if (need_crc)
 229       png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
 230 }
 231
 232 /* Allocate the memory for an info_struct for the application.  We don't
 233  * really need the png_ptr, but it could potentially be useful in the
 234  * future.  This should be used in favour of malloc(png_sizeof(png_info))
 235  * and png_info_init() so that applications that want to use a shared
 236  * libpng don't have to be recompiled if png_info changes size.
 237  */
 238 png_infop PNGAPI
 239 png_create_info_struct(png_structp png_ptr)
 240 {
 241    png_infop info_ptr;
 242
 243    png_debug(1, "in png_create_info_struct");
 244    if (png_ptr == NULL) return (NULL);
 245 #ifdef PNG_USER_MEM_SUPPORTED
 246    info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
 247       png_ptr->malloc_fn, png_ptr->mem_ptr);
 248 #else
 249    info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 250 #endif
 251    if (info_ptr != NULL)
 252       png_info_init_3(&info_ptr, png_sizeof(png_info));
 253
 254    return (info_ptr);
 255 }
 256
 257 /* This function frees the memory associated with a single info struct.
 258  * Normally, one would use either png_destroy_read_struct() or
 259  * png_destroy_write_struct() to free an info struct, but this may be
 260  * useful for some applications.
 261  */
 262 void PNGAPI
 263 png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 264 {
 265    png_infop info_ptr = NULL;
 266    if (png_ptr == NULL) return;
 267
 268    png_debug(1, "in png_destroy_info_struct");
 269    if (info_ptr_ptr != NULL)
 270       info_ptr = *info_ptr_ptr;
 271
 272    if (info_ptr != NULL)
 273    {
 274       png_info_destroy(png_ptr, info_ptr);
 275
 276 #ifdef PNG_USER_MEM_SUPPORTED
 277       png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
 278           png_ptr->mem_ptr);
 279 #else
 280       png_destroy_struct((png_voidp)info_ptr);
 281 #endif
 282       *info_ptr_ptr = NULL;
 283    }
 284 }
 285
 286 /* Initialize the info structure.  This is now an internal function (0.89)
 287  * and applications using it are urged to use png_create_info_struct()
 288  * instead.
 289  */
 290 #if defined(PNG_1_0_X) || defined(PNG_1_2_X)
 291 #undef png_info_init
 292 void PNGAPI
 293 png_info_init(png_infop info_ptr)
 294 {
 295    /* We only come here via pre-1.0.12-compiled applications */
 296    png_info_init_3(&info_ptr, 0);
 297 }
 298 #endif
 299
 300 void PNGAPI
 301 png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
 302 {
 303    png_infop info_ptr = *ptr_ptr;
 304
 305    if (info_ptr == NULL) return;
 306
 307    png_debug(1, "in png_info_init_3");
 308
 309    if (png_sizeof(png_info) > png_info_struct_size)
 310      {
 311        png_destroy_struct(info_ptr);
 312        info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 313        *ptr_ptr = info_ptr;
 314      }
 315
 316    /* set everything to 0 */
 317    png_memset(info_ptr, 0, png_sizeof(png_info));
 318 }
 319
 320 #ifdef PNG_FREE_ME_SUPPORTED
 321 void PNGAPI
 322 png_data_freer(png_structp png_ptr, png_infop info_ptr,
 323    int freer, png_uint_32 mask)
 324 {
 325    png_debug(1, "in png_data_freer");
 326    if (png_ptr == NULL || info_ptr == NULL)
 327       return;
 328    if (freer == PNG_DESTROY_WILL_FREE_DATA)
 329       info_ptr->free_me |= mask;
 330    else if (freer == PNG_USER_WILL_FREE_DATA)
 331       info_ptr->free_me &= ~mask;
 332    else
 333       png_warning(png_ptr,
 334          "Unknown freer parameter in png_data_freer.");
 335 }
 336 #endif
 337
 338 void PNGAPI
 339 png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 340    int num)
 341 {
 342    png_debug(1, "in png_free_data");
 343    if (png_ptr == NULL || info_ptr == NULL)
 344       return;
 345
 346 #if defined(PNG_TEXT_SUPPORTED)
 347 /* free text item num or (if num == -1) all text items */
 348 #ifdef PNG_FREE_ME_SUPPORTED
 349 if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
 350 #else
 351 if (mask & PNG_FREE_TEXT)
 352 #endif
 353 {
 354    if (num != -1)
 355    {
 356      if (info_ptr->text && info_ptr->text[num].key)
 357      {
 358          png_free(png_ptr, info_ptr->text[num].key);
 359          info_ptr->text[num].key = NULL;
 360      }
 361    }
 362    else
 363    {
 364        int i;
 365        for (i = 0; i < info_ptr->num_text; i++)
 366            png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
 367        png_free(png_ptr, info_ptr->text);
 368        info_ptr->text = NULL;
 369        info_ptr->num_text=0;
 370    }
 371 }
 372 #endif
 373
 374 #if defined(PNG_tRNS_SUPPORTED)
 375 /* free any tRNS entry */
 376 #ifdef PNG_FREE_ME_SUPPORTED
 377 if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
 378 #else
 379 if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))
 380 #endif
 381 {
 382     png_free(png_ptr, info_ptr->trans);
 383     info_ptr->trans = NULL;
 384     info_ptr->valid &= ~PNG_INFO_tRNS;
 385 #ifndef PNG_FREE_ME_SUPPORTED
 386     png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
 387 #endif
 388 }
 389 #endif
 390
 391 #if defined(PNG_sCAL_SUPPORTED)
 392 /* free any sCAL entry */
 393 #ifdef PNG_FREE_ME_SUPPORTED
 394 if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
 395 #else
 396 if (mask & PNG_FREE_SCAL)
 397 #endif
 398 {
 399 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
 400     png_free(png_ptr, info_ptr->scal_s_width);
 401     png_free(png_ptr, info_ptr->scal_s_height);
 402     info_ptr->scal_s_width = NULL;
 403     info_ptr->scal_s_height = NULL;
 404 #endif
 405     info_ptr->valid &= ~PNG_INFO_sCAL;
 406 }
 407 #endif
 408
 409 #if defined(PNG_pCAL_SUPPORTED)
 410 /* free any pCAL entry */
 411 #ifdef PNG_FREE_ME_SUPPORTED
 412 if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
 413 #else
 414 if (mask & PNG_FREE_PCAL)
 415 #endif
 416 {
 417     png_free(png_ptr, info_ptr->pcal_purpose);
 418     png_free(png_ptr, info_ptr->pcal_units);
 419     info_ptr->pcal_purpose = NULL;
 420     info_ptr->pcal_units = NULL;
 421     if (info_ptr->pcal_params != NULL)
 422     {
 423         int i;
 424         for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
 425         {
 426           png_free(png_ptr, info_ptr->pcal_params[i]);
 427           info_ptr->pcal_params[i]=NULL;
 428         }
 429         png_free(png_ptr, info_ptr->pcal_params);
 430         info_ptr->pcal_params = NULL;
 431     }
 432     info_ptr->valid &= ~PNG_INFO_pCAL;
 433 }
 434 #endif
 435
 436 #if defined(PNG_iCCP_SUPPORTED)
 437 /* free any iCCP entry */
 438 #ifdef PNG_FREE_ME_SUPPORTED
 439 if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
 440 #else
 441 if (mask & PNG_FREE_ICCP)
 442 #endif
 443 {
 444     png_free(png_ptr, info_ptr->iccp_name);
 445     png_free(png_ptr, info_ptr->iccp_profile);
 446     info_ptr->iccp_name = NULL;
 447     info_ptr->iccp_profile = NULL;
 448     info_ptr->valid &= ~PNG_INFO_iCCP;
 449 }
 450 #endif
 451
 452 #if defined(PNG_sPLT_SUPPORTED)
 453 /* free a given sPLT entry, or (if num == -1) all sPLT entries */
 454 #ifdef PNG_FREE_ME_SUPPORTED
 455 if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
 456 #else
 457 if (mask & PNG_FREE_SPLT)
 458 #endif
 459 {
 460    if (num != -1)
 461    {
 462       if (info_ptr->splt_palettes)
 463       {
 464           png_free(png_ptr, info_ptr->splt_palettes[num].name);
 465           png_free(png_ptr, info_ptr->splt_palettes[num].entries);
 466           info_ptr->splt_palettes[num].name = NULL;
 467           info_ptr->splt_palettes[num].entries = NULL;
 468       }
 469    }
 470    else
 471    {
 472        if (info_ptr->splt_palettes_num)
 473        {
 474          int i;
 475          for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
 476             png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
 477
 478          png_free(png_ptr, info_ptr->splt_palettes);
 479          info_ptr->splt_palettes = NULL;
 480          info_ptr->splt_palettes_num = 0;
 481        }
 482        info_ptr->valid &= ~PNG_INFO_sPLT;
 483    }
 484 }
 485 #endif
 486
 487 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 488   if (png_ptr->unknown_chunk.data)
 489   {
 490     png_free(png_ptr, png_ptr->unknown_chunk.data);
 491     png_ptr->unknown_chunk.data = NULL;
 492   }
 493
 494 #ifdef PNG_FREE_ME_SUPPORTED
 495 if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
 496 #else
 497 if (mask & PNG_FREE_UNKN)
 498 #endif
 499 {
 500    if (num != -1)
 501    {
 502        if (info_ptr->unknown_chunks)
 503        {
 504           png_free(png_ptr, info_ptr->unknown_chunks[num].data);
 505           info_ptr->unknown_chunks[num].data = NULL;
 506        }
 507    }
 508    else
 509    {
 510        int i;
 511
 512        if (info_ptr->unknown_chunks_num)
 513        {
 514          for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
 515             png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
 516
 517          png_free(png_ptr, info_ptr->unknown_chunks);
 518          info_ptr->unknown_chunks = NULL;
 519          info_ptr->unknown_chunks_num = 0;
 520        }
 521    }
 522 }
 523 #endif
 524
 525 #if defined(PNG_hIST_SUPPORTED)
 526 /* free any hIST entry */
 527 #ifdef PNG_FREE_ME_SUPPORTED
 528 if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
 529 #else
 530 if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
 531 #endif
 532 {
 533     png_free(png_ptr, info_ptr->hist);
 534     info_ptr->hist = NULL;
 535     info_ptr->valid &= ~PNG_INFO_hIST;
 536 #ifndef PNG_FREE_ME_SUPPORTED
 537     png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
 538 #endif
 539 }
 540 #endif
 541
 542 /* free any PLTE entry that was internally allocated */
 543 #ifdef PNG_FREE_ME_SUPPORTED
 544 if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
 545 #else
 546 if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
 547 #endif
 548 {
 549     png_zfree(png_ptr, info_ptr->palette);
 550     info_ptr->palette = NULL;
 551     info_ptr->valid &= ~PNG_INFO_PLTE;
 552 #ifndef PNG_FREE_ME_SUPPORTED
 553     png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
 554 #endif
 555     info_ptr->num_palette = 0;
 556 }
 557
 558 #if defined(PNG_INFO_IMAGE_SUPPORTED)
 559 /* free any image bits attached to the info structure */
 560 #ifdef PNG_FREE_ME_SUPPORTED
 561 if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
 562 #else
 563 if (mask & PNG_FREE_ROWS)
 564 #endif
 565 {
 566     if (info_ptr->row_pointers)
 567     {
 568        int row;
 569        for (row = 0; row < (int)info_ptr->height; row++)
 570        {
 571           png_free(png_ptr, info_ptr->row_pointers[row]);
 572           info_ptr->row_pointers[row]=NULL;
 573        }
 574        png_free(png_ptr, info_ptr->row_pointers);
 575        info_ptr->row_pointers=NULL;
 576     }
 577     info_ptr->valid &= ~PNG_INFO_IDAT;
 578 }
 579 #endif
 580
 581 #ifdef PNG_FREE_ME_SUPPORTED
 582    if (num == -1)
 583      info_ptr->free_me &= ~mask;
 584    else
 585      info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
 586 #endif
 587 }
 588
 589 /* This is an internal routine to free any memory that the info struct is
 590  * pointing to before re-using it or freeing the struct itself.  Recall
 591  * that png_free() checks for NULL pointers for us.
 592  */
 593 void /* PRIVATE */
 594 png_info_destroy(png_structp png_ptr, png_infop info_ptr)
 595 {
 596    png_debug(1, "in png_info_destroy");
 597
 598    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 599
 600 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
 601    if (png_ptr->num_chunk_list)
 602    {
 603        png_free(png_ptr, png_ptr->chunk_list);
 604        png_ptr->chunk_list=NULL;
 605        png_ptr->num_chunk_list = 0;
 606    }
 607 #endif
 608
 609    png_info_init_3(&info_ptr, png_sizeof(png_info));
 610 }
 611 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 612
 613 /* This function returns a pointer to the io_ptr associated with the user
 614  * functions.  The application should free any memory associated with this
 615  * pointer before png_write_destroy() or png_read_destroy() are called.
 616  */
 617 png_voidp PNGAPI
 618 png_get_io_ptr(png_structp png_ptr)
 619 {
 620    if (png_ptr == NULL) return (NULL);
 621    return (png_ptr->io_ptr);
 622 }
 623
 624 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 625 #if !defined(PNG_NO_STDIO)
 626 /* Initialize the default input/output functions for the PNG file.  If you
 627  * use your own read or write routines, you can call either png_set_read_fn()
 628  * or png_set_write_fn() instead of png_init_io().  If you have defined
 629  * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
 630  * necessarily available.
 631  */
 632 void PNGAPI
 633 png_init_io(png_structp png_ptr, png_FILE_p fp)
 634 {
 635    png_debug(1, "in png_init_io");
 636    if (png_ptr == NULL) return;
 637    png_ptr->io_ptr = (png_voidp)fp;
 638 }
 639 #endif
 640
 641 #if defined(PNG_TIME_RFC1123_SUPPORTED)
 642 /* Convert the supplied time into an RFC 1123 string suitable for use in
 643  * a "Creation Time" or other text-based time string.
 644  */
 645 png_charp PNGAPI
 646 png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 647 {
 648    static PNG_CONST char short_months[12][4] =
 649         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 650          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 651
 652    if (png_ptr == NULL) return (NULL);
 653    if (png_ptr->time_buffer == NULL)
 654    {
 655       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
 656          png_sizeof(char)));
 657    }
 658
 659 #if defined(_WIN32_WCE)
 660    {
 661       wchar_t time_buf[29];
 662       wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
 663           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 664         ptime->year, ptime->hour % 24, ptime->minute % 60,
 665           ptime->second % 61);
 666       WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,
 667           NULL, NULL);
 668    }
 669 #else
 670 #ifdef USE_FAR_KEYWORD
 671    {
 672       char near_time_buf[29];
 673       png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000",
 674           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 675           ptime->year, ptime->hour % 24, ptime->minute % 60,
 676           ptime->second % 61);
 677       png_memcpy(png_ptr->time_buffer, near_time_buf,
 678           29*png_sizeof(char));
 679    }
 680 #else
 681    png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000",
 682        ptime->day % 32, short_months[(ptime->month - 1) % 12],
 683        ptime->year, ptime->hour % 24, ptime->minute % 60,
 684        ptime->second % 61);
 685 #endif
 686 #endif /* _WIN32_WCE */
 687    return ((png_charp)png_ptr->time_buffer);
 688 }
 689 #endif /* PNG_TIME_RFC1123_SUPPORTED */
 690
 691 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 692
 693 png_charp PNGAPI
 694 png_get_copyright(png_structp png_ptr)
 695 {
 696    png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
 697    return ((png_charp) "\n libpng version 1.2.34 - December 18, 2008\n\
 698    Copyright (c) 1998-2008 Glenn Randers-Pehrson\n\
 699    Copyright (c) 1996-1997 Andreas Dilger\n\
 700    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
 701 }
 702
 703 /* The following return the library version as a short string in the
 704  * format 1.0.0 through 99.99.99zz.  To get the version of *.h files
 705  * used with your application, print out PNG_LIBPNG_VER_STRING, which
 706  * is defined in png.h.
 707  * Note: now there is no difference between png_get_libpng_ver() and
 708  * png_get_header_ver().  Due to the version_nn_nn_nn typedef guard,
 709  * it is guaranteed that png.c uses the correct version of png.h.
 710  */
 711 png_charp PNGAPI
 712 png_get_libpng_ver(png_structp png_ptr)
 713 {
 714    /* Version of *.c files used when building libpng */
 715    png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
 716    return ((png_charp) PNG_LIBPNG_VER_STRING);
 717 }
 718
 719 png_charp PNGAPI
 720 png_get_header_ver(png_structp png_ptr)
 721 {
 722    /* Version of *.h files used when building libpng */
 723    png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
 724    return ((png_charp) PNG_LIBPNG_VER_STRING);
 725 }
 726
 727 png_charp PNGAPI
 728 png_get_header_version(png_structp png_ptr)
 729 {
 730    /* Returns longer string containing both version and date */
 731    png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
 732    return ((png_charp) PNG_HEADER_VERSION_STRING
 733 #ifndef PNG_READ_SUPPORTED
 734    "     (NO READ SUPPORT)"
 735 #endif
 736    "\n");
 737 }
 738
 739 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 740 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 741 int PNGAPI
 742 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 743 {
 744    /* check chunk_name and return "keep" value if it's on the list, else 0 */
 745    int i;
 746    png_bytep p;
 747    if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list<=0)
 748       return 0;
 749    p = png_ptr->chunk_list + png_ptr->num_chunk_list*5 - 5;
 750    for (i = png_ptr->num_chunk_list; i; i--, p -= 5)
 751       if (!png_memcmp(chunk_name, p, 4))
 752         return ((int)*(p + 4));
 753    return 0;
 754 }
 755 #endif
 756
 757 /* This function, added to libpng-1.0.6g, is untested. */
 758 int PNGAPI
 759 png_reset_zstream(png_structp png_ptr)
 760 {
 761    if (png_ptr == NULL) return Z_STREAM_ERROR;
 762    return (inflateReset(&png_ptr->zstream));
 763 }
 764 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 765
 766 /* This function was added to libpng-1.0.7 */
 767 png_uint_32 PNGAPI
 768 png_access_version_number(void)
 769 {
 770    /* Version of *.c files used when building libpng */
 771    return((png_uint_32) PNG_LIBPNG_VER);
 772 }
 773
 774
 775 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ASSEMBLER_CODE_SUPPORTED)
 776 #if !defined(PNG_1_0_X)
 777 /* this function was added to libpng 1.2.0 */
 778 int PNGAPI
 779 png_mmx_support(void)
 780 {
 781    /* obsolete, to be removed from libpng-1.4.0 */
 782     return -1;
 783 }
 784 #endif /* PNG_1_0_X */
 785 #endif /* PNG_READ_SUPPORTED && PNG_ASSEMBLER_CODE_SUPPORTED */
 786
 787 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 788 #ifdef PNG_SIZE_T
 789 /* Added at libpng version 1.2.6 */
 790    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
 791 png_size_t PNGAPI
 792 png_convert_size(size_t size)
 793 {
 794   if (size > (png_size_t)-1)
 795      PNG_ABORT();  /* We haven't got access to png_ptr, so no png_error() */
 796   return ((png_size_t)size);
 797 }
 798 #endif /* PNG_SIZE_T */
 799
 800 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
 801 #if defined(PNG_cHRM_SUPPORTED)
 802 #if !defined(PNG_NO_CHECK_cHRM)
 803 /*
 804  Multiply two 32-bit numbers, V1 and V2, using 32-bit
 805  arithmetic, to produce a 64 bit result in the HI/LO words.
 806
 807           A B
 808         x C D
 809        ------
 810       AD || BD
 811 AC || CB || 0
 812
 813  where A and B are the high and low 16-bit words of V1,
 814  C and D are the 16-bit words of V2, AD is the product of
 815  A and D, and X || Y is (X << 16) + Y.
 816 */
 817
 818 void png_64bit_product (long v1, long v2, unsigned long *hi_product,
 819    unsigned long *lo_product)
 820 {
 821  int a, b, c, d;
 822  long lo, hi, x, y;
 823
 824  a = (v1 >> 16) & 0xffff;
 825  b = v1 & 0xffff;
 826  c = (v2 >> 16) & 0xffff;
 827  d = v2 & 0xffff;
 828
 829  lo = b * d;                   /* BD */
 830  x = a * d + c * b;            /* AD + CB */
 831  y = ((lo >> 16) & 0xffff) + x;
 832
 833  lo = (lo & 0xffff) | ((y & 0xffff) << 16);
 834  hi = (y >> 16) & 0xffff;
 835
 836  hi += a * c;                  /* AC */
 837
 838  *hi_product = (unsigned long)hi;
 839  *lo_product = (unsigned long)lo;
 840 }
 841 int /* private */
 842 png_check_cHRM_fixed(png_structp png_ptr,
 843    png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
 844    png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
 845    png_fixed_point blue_x, png_fixed_point blue_y)
 846 {
 847    int ret = 1;
 848    unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
 849
 850    png_debug(1, "in function png_check_cHRM_fixed");
 851    if (png_ptr == NULL)
 852       return 0;
 853
 854    if (white_x < 0 || white_y <= 0 ||
 855          red_x < 0 ||   red_y <  0 ||
 856        green_x < 0 || green_y <  0 ||
 857         blue_x < 0 ||  blue_y <  0)
 858    {
 859       png_warning(png_ptr,
 860         "Ignoring attempt to set negative chromaticity value");
 861       ret = 0;
 862    }
 863    if (white_x > (png_fixed_point) PNG_UINT_31_MAX ||
 864        white_y > (png_fixed_point) PNG_UINT_31_MAX ||
 865          red_x > (png_fixed_point) PNG_UINT_31_MAX ||
 866          red_y > (png_fixed_point) PNG_UINT_31_MAX ||
 867        green_x > (png_fixed_point) PNG_UINT_31_MAX ||
 868        green_y > (png_fixed_point) PNG_UINT_31_MAX ||
 869         blue_x > (png_fixed_point) PNG_UINT_31_MAX ||
 870         blue_y > (png_fixed_point) PNG_UINT_31_MAX )
 871    {
 872       png_warning(png_ptr,
 873         "Ignoring attempt to set chromaticity value exceeding 21474.83");
 874       ret = 0;
 875    }
 876    if (white_x > 100000L - white_y)
 877    {
 878       png_warning(png_ptr, "Invalid cHRM white point");
 879       ret = 0;
 880    }
 881    if (red_x > 100000L - red_y)
 882    {
 883       png_warning(png_ptr, "Invalid cHRM red point");
 884       ret = 0;
 885    }
 886    if (green_x > 100000L - green_y)
 887    {
 888       png_warning(png_ptr, "Invalid cHRM green point");
 889       ret = 0;
 890    }
 891    if (blue_x > 100000L - blue_y)
 892    {
 893       png_warning(png_ptr, "Invalid cHRM blue point");
 894       ret = 0;
 895    }
 896
 897    png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
 898    png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
 899
 900    if (xy_hi == yx_hi && xy_lo == yx_lo)
 901    {
 902       png_warning(png_ptr,
 903          "Ignoring attempt to set cHRM RGB triangle with zero area");
 904       ret = 0;
 905    }
 906
 907    return ret;
 908 }
 909 #endif /* NO_PNG_CHECK_cHRM */
 910 #endif /* PNG_cHRM_SUPPORTED */
 911 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */