src/png/png.c

   1
   2 /* png.c - location for general purpose libpng functions
   3  *
   4  * Last changed in libpng 1.4.2 [May 6, 2010]
   5  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  */
  13
  14 #define PNG_NO_EXTERN
  15 #define PNG_NO_PEDANTIC_WARNINGS
  16 #include "png.h"
  17 #include "pngpriv.h"
  18
  19 /* Generate a compiler error if there is an old png.h in the search path. */
  20 typedef version_1_4_4 Your_png_h_is_not_version_1_4_4;
  21
  22 /* Version information for C files.  This had better match the version
  23  * string defined in png.h.
  24  */
  25
  26 /* Tells libpng that we have already handled the first "num_bytes" bytes
  27  * of the PNG file signature.  If the PNG data is embedded into another
  28  * stream we can set num_bytes = 8 so that libpng will not attempt to read
  29  * or write any of the magic bytes before it starts on the IHDR.
  30  */
  31
  32 #ifdef PNG_READ_SUPPORTED
  33 void PNGAPI
  34 png_set_sig_bytes(png_structp png_ptr, int num_bytes)
  35 {
  36    png_debug(1, "in png_set_sig_bytes");
  37
  38    if (png_ptr == NULL)
  39       return;
  40
  41    if (num_bytes > 8)
  42       png_error(png_ptr, "Too many bytes for PNG signature");
  43
  44    png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
  45 }
  46
  47 /* Checks whether the supplied bytes match the PNG signature.  We allow
  48  * checking less than the full 8-byte signature so that those apps that
  49  * already read the first few bytes of a file to determine the file type
  50  * can simply check the remaining bytes for extra assurance.  Returns
  51  * an integer less than, equal to, or greater than zero if sig is found,
  52  * respectively, to be less than, to match, or be greater than the correct
  53  * PNG signature (this is the same behaviour as strcmp, memcmp, etc).
  54  */
  55 int PNGAPI
  56 png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
  57 {
  58    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
  59    if (num_to_check > 8)
  60       num_to_check = 8;
  61    else if (num_to_check < 1)
  62       return (-1);
  63
  64    if (start > 7)
  65       return (-1);
  66
  67    if (start + num_to_check > 8)
  68       num_to_check = 8 - start;
  69
  70    return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
  71 }
  72
  73 #endif /* PNG_READ_SUPPORTED */
  74
  75 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
  76 /* Function to allocate memory for zlib and clear it to 0. */
  77 voidpf /* PRIVATE */
  78 png_zalloc(voidpf png_ptr, uInt items, uInt size)
  79 {
  80    png_voidp ptr;
  81    png_structp p=(png_structp)png_ptr;
  82    png_uint_32 save_flags=p->flags;
  83    png_alloc_size_t num_bytes;
  84
  85    if (png_ptr == NULL)
  86       return (NULL);
  87    if (items > PNG_UINT_32_MAX/size)
  88    {
  89      png_warning (p, "Potential overflow in png_zalloc()");
  90      return (NULL);
  91    }
  92    num_bytes = (png_alloc_size_t)items * size;
  93
  94    p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
  95    ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
  96    p->flags=save_flags;
  97
  98    return ((voidpf)ptr);
  99 }
 100
 101 /* Function to free memory for zlib */
 102 void /* PRIVATE */
 103 png_zfree(voidpf png_ptr, voidpf ptr)
 104 {
 105    png_free((png_structp)png_ptr, (png_voidp)ptr);
 106 }
 107
 108 /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
 109  * in case CRC is > 32 bits to leave the top bits 0.
 110  */
 111 void /* PRIVATE */
 112 png_reset_crc(png_structp png_ptr)
 113 {
 114    png_ptr->crc = crc32(0, Z_NULL, 0);
 115 }
 116
 117 /* Calculate the CRC over a section of data.  We can only pass as
 118  * much data to this routine as the largest single buffer size.  We
 119  * also check that this data will actually be used before going to the
 120  * trouble of calculating it.
 121  */
 122 void /* PRIVATE */
 123 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
 124 {
 125    int need_crc = 1;
 126
 127    if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
 128    {
 129       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
 130           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
 131          need_crc = 0;
 132    }
 133    else                                                    /* critical */
 134    {
 135       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
 136          need_crc = 0;
 137    }
 138
 139    if (need_crc)
 140       png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
 141 }
 142
 143 /* Allocate the memory for an info_struct for the application.  We don't
 144  * really need the png_ptr, but it could potentially be useful in the
 145  * future.  This should be used in favour of malloc(png_sizeof(png_info))
 146  * and png_info_init() so that applications that want to use a shared
 147  * libpng don't have to be recompiled if png_info changes size.
 148  */
 149 png_infop PNGAPI
 150 png_create_info_struct(png_structp png_ptr)
 151 {
 152    png_infop info_ptr;
 153
 154    png_debug(1, "in png_create_info_struct");
 155
 156    if (png_ptr == NULL)
 157       return (NULL);
 158
 159 #ifdef PNG_USER_MEM_SUPPORTED
 160    info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
 161       png_ptr->malloc_fn, png_ptr->mem_ptr);
 162 #else
 163    info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 164 #endif
 165    if (info_ptr != NULL)
 166       png_info_init_3(&info_ptr, png_sizeof(png_info));
 167
 168    return (info_ptr);
 169 }
 170
 171 /* This function frees the memory associated with a single info struct.
 172  * Normally, one would use either png_destroy_read_struct() or
 173  * png_destroy_write_struct() to free an info struct, but this may be
 174  * useful for some applications.
 175  */
 176 void PNGAPI
 177 png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 178 {
 179    png_infop info_ptr = NULL;
 180
 181    png_debug(1, "in png_destroy_info_struct");
 182
 183    if (png_ptr == NULL)
 184       return;
 185
 186    if (info_ptr_ptr != NULL)
 187       info_ptr = *info_ptr_ptr;
 188
 189    if (info_ptr != NULL)
 190    {
 191       png_info_destroy(png_ptr, info_ptr);
 192
 193 #ifdef PNG_USER_MEM_SUPPORTED
 194       png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
 195           png_ptr->mem_ptr);
 196 #else
 197       png_destroy_struct((png_voidp)info_ptr);
 198 #endif
 199       *info_ptr_ptr = NULL;
 200    }
 201 }
 202
 203 /* Initialize the info structure.  This is now an internal function (0.89)
 204  * and applications using it are urged to use png_create_info_struct()
 205  * instead.
 206  */
 207
 208 void PNGAPI
 209 png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
 210 {
 211    png_infop info_ptr = *ptr_ptr;
 212
 213    png_debug(1, "in png_info_init_3");
 214
 215    if (info_ptr == NULL)
 216       return;
 217
 218    if (png_sizeof(png_info) > png_info_struct_size)
 219    {
 220       png_destroy_struct(info_ptr);
 221       info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
 222       *ptr_ptr = info_ptr;
 223    }
 224
 225    /* Set everything to 0 */
 226    png_memset(info_ptr, 0, png_sizeof(png_info));
 227 }
 228
 229 void PNGAPI
 230 png_data_freer(png_structp png_ptr, png_infop info_ptr,
 231    int freer, png_uint_32 mask)
 232 {
 233    png_debug(1, "in png_data_freer");
 234
 235    if (png_ptr == NULL || info_ptr == NULL)
 236       return;
 237
 238    if (freer == PNG_DESTROY_WILL_FREE_DATA)
 239       info_ptr->free_me |= mask;
 240    else if (freer == PNG_USER_WILL_FREE_DATA)
 241       info_ptr->free_me &= ~mask;
 242    else
 243       png_warning(png_ptr,
 244          "Unknown freer parameter in png_data_freer");
 245 }
 246
 247 void PNGAPI
 248 png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 249    int num)
 250 {
 251    png_debug(1, "in png_free_data");
 252
 253    if (png_ptr == NULL || info_ptr == NULL)
 254       return;
 255
 256 #ifdef PNG_TEXT_SUPPORTED
 257    /* Free text item num or (if num == -1) all text items */
 258    if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
 259    {
 260       if (num != -1)
 261       {
 262          if (info_ptr->text && info_ptr->text[num].key)
 263          {
 264             png_free(png_ptr, info_ptr->text[num].key);
 265             info_ptr->text[num].key = NULL;
 266          }
 267       }
 268       else
 269       {
 270          int i;
 271          for (i = 0; i < info_ptr->num_text; i++)
 272              png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
 273          png_free(png_ptr, info_ptr->text);
 274          info_ptr->text = NULL;
 275          info_ptr->num_text=0;
 276       }
 277    }
 278 #endif
 279
 280 #ifdef PNG_tRNS_SUPPORTED
 281    /* Free any tRNS entry */
 282    if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
 283    {
 284       png_free(png_ptr, info_ptr->trans_alpha);
 285       info_ptr->trans_alpha = NULL;
 286       info_ptr->valid &= ~PNG_INFO_tRNS;
 287    }
 288 #endif
 289
 290 #ifdef PNG_sCAL_SUPPORTED
 291    /* Free any sCAL entry */
 292    if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
 293    {
 294 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
 295       png_free(png_ptr, info_ptr->scal_s_width);
 296       png_free(png_ptr, info_ptr->scal_s_height);
 297       info_ptr->scal_s_width = NULL;
 298       info_ptr->scal_s_height = NULL;
 299 #endif
 300       info_ptr->valid &= ~PNG_INFO_sCAL;
 301    }
 302 #endif
 303
 304 #ifdef PNG_pCAL_SUPPORTED
 305    /* Free any pCAL entry */
 306    if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
 307    {
 308       png_free(png_ptr, info_ptr->pcal_purpose);
 309       png_free(png_ptr, info_ptr->pcal_units);
 310       info_ptr->pcal_purpose = NULL;
 311       info_ptr->pcal_units = NULL;
 312       if (info_ptr->pcal_params != NULL)
 313          {
 314             int i;
 315             for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
 316             {
 317                png_free(png_ptr, info_ptr->pcal_params[i]);
 318                info_ptr->pcal_params[i] = NULL;
 319             }
 320             png_free(png_ptr, info_ptr->pcal_params);
 321             info_ptr->pcal_params = NULL;
 322          }
 323       info_ptr->valid &= ~PNG_INFO_pCAL;
 324    }
 325 #endif
 326
 327 #ifdef PNG_iCCP_SUPPORTED
 328    /* Free any iCCP entry */
 329    if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
 330    {
 331       png_free(png_ptr, info_ptr->iccp_name);
 332       png_free(png_ptr, info_ptr->iccp_profile);
 333       info_ptr->iccp_name = NULL;
 334       info_ptr->iccp_profile = NULL;
 335       info_ptr->valid &= ~PNG_INFO_iCCP;
 336    }
 337 #endif
 338
 339 #ifdef PNG_sPLT_SUPPORTED
 340    /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
 341    if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
 342    {
 343       if (num != -1)
 344       {
 345          if (info_ptr->splt_palettes)
 346          {
 347             png_free(png_ptr, info_ptr->splt_palettes[num].name);
 348             png_free(png_ptr, info_ptr->splt_palettes[num].entries);
 349             info_ptr->splt_palettes[num].name = NULL;
 350             info_ptr->splt_palettes[num].entries = NULL;
 351          }
 352       }
 353       else
 354       {
 355          if (info_ptr->splt_palettes_num)
 356          {
 357             int i;
 358             for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
 359                png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
 360
 361             png_free(png_ptr, info_ptr->splt_palettes);
 362             info_ptr->splt_palettes = NULL;
 363             info_ptr->splt_palettes_num = 0;
 364          }
 365          info_ptr->valid &= ~PNG_INFO_sPLT;
 366       }
 367    }
 368 #endif
 369
 370 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 371    if (png_ptr->unknown_chunk.data)
 372    {
 373       png_free(png_ptr, png_ptr->unknown_chunk.data);
 374       png_ptr->unknown_chunk.data = NULL;
 375    }
 376
 377    if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
 378    {
 379       if (num != -1)
 380       {
 381           if (info_ptr->unknown_chunks)
 382           {
 383              png_free(png_ptr, info_ptr->unknown_chunks[num].data);
 384              info_ptr->unknown_chunks[num].data = NULL;
 385           }
 386       }
 387       else
 388       {
 389          int i;
 390
 391          if (info_ptr->unknown_chunks_num)
 392          {
 393             for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
 394                png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
 395
 396             png_free(png_ptr, info_ptr->unknown_chunks);
 397             info_ptr->unknown_chunks = NULL;
 398             info_ptr->unknown_chunks_num = 0;
 399          }
 400       }
 401    }
 402 #endif
 403
 404 #ifdef PNG_hIST_SUPPORTED
 405    /* Free any hIST entry */
 406    if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
 407    {
 408       png_free(png_ptr, info_ptr->hist);
 409       info_ptr->hist = NULL;
 410       info_ptr->valid &= ~PNG_INFO_hIST;
 411    }
 412 #endif
 413
 414    /* Free any PLTE entry that was internally allocated */
 415    if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
 416    {
 417       png_zfree(png_ptr, info_ptr->palette);
 418       info_ptr->palette = NULL;
 419       info_ptr->valid &= ~PNG_INFO_PLTE;
 420       info_ptr->num_palette = 0;
 421    }
 422
 423 #ifdef PNG_INFO_IMAGE_SUPPORTED
 424    /* Free any image bits attached to the info structure */
 425    if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
 426    {
 427       if (info_ptr->row_pointers)
 428       {
 429          int row;
 430          for (row = 0; row < (int)info_ptr->height; row++)
 431          {
 432             png_free(png_ptr, info_ptr->row_pointers[row]);
 433             info_ptr->row_pointers[row] = NULL;
 434          }
 435          png_free(png_ptr, info_ptr->row_pointers);
 436          info_ptr->row_pointers = NULL;
 437       }
 438       info_ptr->valid &= ~PNG_INFO_IDAT;
 439    }
 440 #endif
 441
 442    if (num == -1)
 443       info_ptr->free_me &= ~mask;
 444    else
 445       info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
 446 }
 447
 448 /* This is an internal routine to free any memory that the info struct is
 449  * pointing to before re-using it or freeing the struct itself.  Recall
 450  * that png_free() checks for NULL pointers for us.
 451  */
 452 void /* PRIVATE */
 453 png_info_destroy(png_structp png_ptr, png_infop info_ptr)
 454 {
 455    png_debug(1, "in png_info_destroy");
 456
 457    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 458
 459 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 460    if (png_ptr->num_chunk_list)
 461    {
 462       png_free(png_ptr, png_ptr->chunk_list);
 463       png_ptr->chunk_list = NULL;
 464       png_ptr->num_chunk_list = 0;
 465    }
 466 #endif
 467
 468    png_info_init_3(&info_ptr, png_sizeof(png_info));
 469 }
 470 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 471
 472 /* This function returns a pointer to the io_ptr associated with the user
 473  * functions.  The application should free any memory associated with this
 474  * pointer before png_write_destroy() or png_read_destroy() are called.
 475  */
 476 png_voidp PNGAPI
 477 png_get_io_ptr(png_structp png_ptr)
 478 {
 479    if (png_ptr == NULL)
 480       return (NULL);
 481    return (png_ptr->io_ptr);
 482 }
 483
 484 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 485 #ifdef PNG_STDIO_SUPPORTED
 486 /* Initialize the default input/output functions for the PNG file.  If you
 487  * use your own read or write routines, you can call either png_set_read_fn()
 488  * or png_set_write_fn() instead of png_init_io().  If you have defined
 489  * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
 490  * necessarily available.
 491  */
 492 void PNGAPI
 493 png_init_io(png_structp png_ptr, png_FILE_p fp)
 494 {
 495    png_debug(1, "in png_init_io");
 496
 497    if (png_ptr == NULL)
 498       return;
 499
 500    png_ptr->io_ptr = (png_voidp)fp;
 501 }
 502 #endif
 503
 504 #ifdef PNG_TIME_RFC1123_SUPPORTED
 505 /* Convert the supplied time into an RFC 1123 string suitable for use in
 506  * a "Creation Time" or other text-based time string.
 507  */
 508 png_charp PNGAPI
 509 png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 510 {
 511    static PNG_CONST char short_months[12][4] =
 512         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 513          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 514
 515    if (png_ptr == NULL)
 516       return (NULL);
 517    if (png_ptr->time_buffer == NULL)
 518    {
 519       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
 520          png_sizeof(char)));
 521    }
 522
 523 #ifdef USE_FAR_KEYWORD
 524    {
 525       char near_time_buf[29];
 526       png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000",
 527           ptime->day % 32, short_months[(ptime->month - 1) % 12],
 528           ptime->year, ptime->hour % 24, ptime->minute % 60,
 529           ptime->second % 61);
 530       png_memcpy(png_ptr->time_buffer, near_time_buf,
 531           29*png_sizeof(char));
 532    }
 533 #else
 534    png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000",
 535        ptime->day % 32, short_months[(ptime->month - 1) % 12],
 536        ptime->year, ptime->hour % 24, ptime->minute % 60,
 537        ptime->second % 61);
 538 #endif
 539    return ((png_charp)png_ptr->time_buffer);
 540 }
 541 #endif /* PNG_TIME_RFC1123_SUPPORTED */
 542
 543 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 544
 545 png_charp PNGAPI
 546 png_get_copyright(png_structp png_ptr)
 547 {
 548    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 549 #ifdef PNG_STRING_COPYRIGHT
 550       return PNG_STRING_COPYRIGHT
 551 #else
 552 #ifdef __STDC__
 553    return ((png_charp) PNG_STRING_NEWLINE \
 554      "libpng version 1.4.4 - September 23, 2010" PNG_STRING_NEWLINE \
 555      "Copyright (c) 1998-2010 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
 556      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
 557      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
 558      PNG_STRING_NEWLINE);
 559 #else
 560       return ((png_charp) "libpng version 1.4.4 - September 23, 2010\
 561       Copyright (c) 1998-2010 Glenn Randers-Pehrson\
 562       Copyright (c) 1996-1997 Andreas Dilger\
 563       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
 564 #endif
 565 #endif
 566 }
 567
 568 /* The following return the library version as a short string in the
 569  * format 1.0.0 through 99.99.99zz.  To get the version of *.h files
 570  * used with your application, print out PNG_LIBPNG_VER_STRING, which
 571  * is defined in png.h.
 572  * Note: now there is no difference between png_get_libpng_ver() and
 573  * png_get_header_ver().  Due to the version_nn_nn_nn typedef guard,
 574  * it is guaranteed that png.c uses the correct version of png.h.
 575  */
 576 png_charp PNGAPI
 577 png_get_libpng_ver(png_structp png_ptr)
 578 {
 579    /* Version of *.c files used when building libpng */
 580    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 581    return ((png_charp) PNG_LIBPNG_VER_STRING);
 582 }
 583
 584 png_charp PNGAPI
 585 png_get_header_ver(png_structp png_ptr)
 586 {
 587    /* Version of *.h files used when building libpng */
 588    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 589    return ((png_charp) PNG_LIBPNG_VER_STRING);
 590 }
 591
 592 png_charp PNGAPI
 593 png_get_header_version(png_structp png_ptr)
 594 {
 595    /* Returns longer string containing both version and date */
 596    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 597 #ifdef __STDC__
 598    return ((png_charp) PNG_HEADER_VERSION_STRING
 599 #ifndef PNG_READ_SUPPORTED
 600    "     (NO READ SUPPORT)"
 601 #endif
 602    PNG_STRING_NEWLINE);
 603 #else
 604    return ((png_charp) PNG_HEADER_VERSION_STRING);
 605 #endif
 606 }
 607
 608 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 609 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 610 int PNGAPI
 611 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 612 {
 613    /* Check chunk_name and return "keep" value if it's on the list, else 0 */
 614    int i;
 615    png_bytep p;
 616    if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list<=0)
 617       return 0;
 618    p = png_ptr->chunk_list + png_ptr->num_chunk_list*5 - 5;
 619    for (i = png_ptr->num_chunk_list; i; i--, p -= 5)
 620       if (!png_memcmp(chunk_name, p, 4))
 621         return ((int)*(p + 4));
 622    return 0;
 623 }
 624 #endif
 625 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 626
 627 #ifdef PNG_READ_SUPPORTED
 628 /* This function, added to libpng-1.0.6g, is untested. */
 629 int PNGAPI
 630 png_reset_zstream(png_structp png_ptr)
 631 {
 632    if (png_ptr == NULL)
 633       return Z_STREAM_ERROR;
 634    return (inflateReset(&png_ptr->zstream));
 635 }
 636 #endif /* PNG_READ_SUPPORTED */
 637
 638 /* This function was added to libpng-1.0.7 */
 639 png_uint_32 PNGAPI
 640 png_access_version_number(void)
 641 {
 642    /* Version of *.c files used when building libpng */
 643    return((png_uint_32) PNG_LIBPNG_VER);
 644 }
 645
 646
 647
 648 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 649 #ifdef PNG_SIZE_T
 650 /* Added at libpng version 1.2.6 */
 651    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
 652 png_size_t PNGAPI
 653 png_convert_size(size_t size)
 654 {
 655    if (size > (png_size_t)-1)
 656       PNG_ABORT();  /* We haven't got access to png_ptr, so no png_error() */
 657    return ((png_size_t)size);
 658 }
 659 #endif /* PNG_SIZE_T */
 660
 661 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
 662 #ifdef PNG_cHRM_SUPPORTED
 663 #ifdef PNG_CHECK_cHRM_SUPPORTED
 664
 665 /*
 666  *    Multiply two 32-bit numbers, V1 and V2, using 32-bit
 667  *    arithmetic, to produce a 64 bit result in the HI/LO words.
 668  *
 669  *                  A B
 670  *                x C D
 671  *               ------
 672  *              AD || BD
 673  *        AC || CB || 0
 674  *
 675  *    where A and B are the high and low 16-bit words of V1,
 676  *    C and D are the 16-bit words of V2, AD is the product of
 677  *    A and D, and X || Y is (X << 16) + Y.
 678 */
 679
 680 void /* PRIVATE */
 681 png_64bit_product (long v1, long v2, unsigned long *hi_product,
 682    unsigned long *lo_product)
 683 {
 684    int a, b, c, d;
 685    long lo, hi, x, y;
 686
 687    a = (v1 >> 16) & 0xffff;
 688    b = v1 & 0xffff;
 689    c = (v2 >> 16) & 0xffff;
 690    d = v2 & 0xffff;
 691
 692    lo = b * d;                   /* BD */
 693    x = a * d + c * b;            /* AD + CB */
 694    y = ((lo >> 16) & 0xffff) + x;
 695
 696    lo = (lo & 0xffff) | ((y & 0xffff) << 16);
 697    hi = (y >> 16) & 0xffff;
 698
 699    hi += a * c;                  /* AC */
 700
 701    *hi_product = (unsigned long)hi;
 702    *lo_product = (unsigned long)lo;
 703 }
 704
 705 int /* PRIVATE */
 706 png_check_cHRM_fixed(png_structp png_ptr,
 707    png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
 708    png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
 709    png_fixed_point blue_x, png_fixed_point blue_y)
 710 {
 711    int ret = 1;
 712    unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
 713
 714    png_debug(1, "in function png_check_cHRM_fixed");
 715
 716    if (png_ptr == NULL)
 717       return 0;
 718
 719    if (white_x < 0 || white_y <= 0 ||
 720          red_x < 0 ||   red_y <  0 ||
 721        green_x < 0 || green_y <  0 ||
 722         blue_x < 0 ||  blue_y <  0)
 723    {
 724       png_warning(png_ptr,
 725         "Ignoring attempt to set negative chromaticity value");
 726       ret = 0;
 727    }
 728    if (white_x > (png_fixed_point) PNG_UINT_31_MAX ||
 729        white_y > (png_fixed_point) PNG_UINT_31_MAX ||
 730          red_x > (png_fixed_point) PNG_UINT_31_MAX ||
 731          red_y > (png_fixed_point) PNG_UINT_31_MAX ||
 732        green_x > (png_fixed_point) PNG_UINT_31_MAX ||
 733        green_y > (png_fixed_point) PNG_UINT_31_MAX ||
 734         blue_x > (png_fixed_point) PNG_UINT_31_MAX ||
 735         blue_y > (png_fixed_point) PNG_UINT_31_MAX )
 736    {
 737       png_warning(png_ptr,
 738         "Ignoring attempt to set chromaticity value exceeding 21474.83");
 739       ret = 0;
 740    }
 741    if (white_x > 100000L - white_y)
 742    {
 743       png_warning(png_ptr, "Invalid cHRM white point");
 744       ret = 0;
 745    }
 746    if (red_x > 100000L - red_y)
 747    {
 748       png_warning(png_ptr, "Invalid cHRM red point");
 749       ret = 0;
 750    }
 751    if (green_x > 100000L - green_y)
 752    {
 753       png_warning(png_ptr, "Invalid cHRM green point");
 754       ret = 0;
 755    }
 756    if (blue_x > 100000L - blue_y)
 757    {
 758       png_warning(png_ptr, "Invalid cHRM blue point");
 759       ret = 0;
 760    }
 761
 762    png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
 763    png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
 764
 765    if (xy_hi == yx_hi && xy_lo == yx_lo)
 766    {
 767       png_warning(png_ptr,
 768          "Ignoring attempt to set cHRM RGB triangle with zero area");
 769       ret = 0;
 770    }
 771
 772    return ret;
 773 }
 774 #endif /* PNG_CHECK_cHRM_SUPPORTED */
 775 #endif /* PNG_cHRM_SUPPORTED */
 776
 777 void /* PRIVATE */
 778 png_check_IHDR(png_structp png_ptr,
 779    png_uint_32 width, png_uint_32 height, int bit_depth,
 780    int color_type, int interlace_type, int compression_type,
 781    int filter_type)
 782 {
 783    int error = 0;
 784
 785    /* Check for width and height valid values */
 786    if (width == 0)
 787    {
 788       png_warning(png_ptr, "Image width is zero in IHDR");
 789       error = 1;
 790    }
 791
 792    if (height == 0)
 793    {
 794       png_warning(png_ptr, "Image height is zero in IHDR");
 795       error = 1;
 796    }
 797
 798 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
 799    if (width > png_ptr->user_width_max || width > PNG_USER_WIDTH_MAX)
 800 #else
 801    if (width > PNG_USER_WIDTH_MAX)
 802 #endif
 803    {
 804       png_warning(png_ptr, "Image width exceeds user limit in IHDR");
 805       error = 1;
 806    }
 807
 808 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
 809    if (height > png_ptr->user_height_max || height > PNG_USER_HEIGHT_MAX)
 810 #else
 811    if (height > PNG_USER_HEIGHT_MAX)
 812 #endif
 813    {
 814       png_warning(png_ptr, "Image height exceeds user limit in IHDR");
 815       error = 1;
 816    }
 817
 818    if (width > PNG_UINT_31_MAX)
 819    {
 820       png_warning(png_ptr, "Invalid image width in IHDR");
 821       error = 1;
 822    }
 823
 824    if ( height > PNG_UINT_31_MAX)
 825    {
 826       png_warning(png_ptr, "Invalid image height in IHDR");
 827       error = 1;
 828    }
 829
 830    if ( width > (PNG_UINT_32_MAX
 831                  >> 3)      /* 8-byte RGBA pixels */
 832                  - 64       /* bigrowbuf hack */
 833                  - 1        /* filter byte */
 834                  - 7*8      /* rounding of width to multiple of 8 pixels */
 835                  - 8)       /* extra max_pixel_depth pad */
 836       png_warning(png_ptr, "Width is too large for libpng to process pixels");
 837
 838    /* Check other values */
 839    if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
 840        bit_depth != 8 && bit_depth != 16)
 841    {
 842       png_warning(png_ptr, "Invalid bit depth in IHDR");
 843       error = 1;
 844    }
 845
 846    if (color_type < 0 || color_type == 1 ||
 847        color_type == 5 || color_type > 6)
 848    {
 849       png_warning(png_ptr, "Invalid color type in IHDR");
 850       error = 1;
 851    }
 852
 853    if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
 854        ((color_type == PNG_COLOR_TYPE_RGB ||
 855          color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
 856          color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
 857    {
 858       png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
 859       error = 1;
 860    }
 861
 862    if (interlace_type >= PNG_INTERLACE_LAST)
 863    {
 864       png_warning(png_ptr, "Unknown interlace method in IHDR");
 865       error = 1;
 866    }
 867
 868    if (compression_type != PNG_COMPRESSION_TYPE_BASE)
 869    {
 870       png_warning(png_ptr, "Unknown compression method in IHDR");
 871       error = 1;
 872    }
 873
 874 #ifdef PNG_MNG_FEATURES_SUPPORTED
 875    /* Accept filter_method 64 (intrapixel differencing) only if
 876     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
 877     * 2. Libpng did not read a PNG signature (this filter_method is only
 878     *    used in PNG datastreams that are embedded in MNG datastreams) and
 879     * 3. The application called png_permit_mng_features with a mask that
 880     *    included PNG_FLAG_MNG_FILTER_64 and
 881     * 4. The filter_method is 64 and
 882     * 5. The color_type is RGB or RGBA
 883     */
 884    if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
 885        png_ptr->mng_features_permitted)
 886       png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
 887
 888    if (filter_type != PNG_FILTER_TYPE_BASE)
 889    {
 890       if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
 891          (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
 892          ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
 893          (color_type == PNG_COLOR_TYPE_RGB ||
 894          color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
 895       {
 896          png_warning(png_ptr, "Unknown filter method in IHDR");
 897          error = 1;
 898       }
 899
 900       if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
 901       {
 902          png_warning(png_ptr, "Invalid filter method in IHDR");
 903          error = 1;
 904       }
 905    }
 906
 907 #else
 908    if (filter_type != PNG_FILTER_TYPE_BASE)
 909    {
 910       png_warning(png_ptr, "Unknown filter method in IHDR");
 911       error = 1;
 912    }
 913 #endif
 914
 915    if (error == 1)
 916       png_error(png_ptr, "Invalid IHDR data");
 917 }
 918 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */