src/png/pngread.c

   1
   2 /* pngread.c - read a PNG file
   3  *
   4  * libpng 1.0.1
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
   7  * Copyright (c) 1996, 1997 Andreas Dilger
   8  * Copyright (c) 1998, Glenn Randers-Pehrson
   9  * March 15, 1998
  10  *
  11  * This file contains routines that an application calls directly to
  12  * read a PNG file or stream.
  13  */
  14
  15 #define PNG_INTERNAL
  16 #include "../png/png.h"
  17
  18 /* Create a PNG structure for reading, and allocate any memory needed. */
  19 png_structp
  20 png_create_read_struct(png_const_charp user_png_ver, voidp error_ptr,
  21    png_error_ptr error_fn, png_error_ptr warn_fn)
  22 {
  23    png_structp png_ptr;
  24 #ifdef USE_FAR_KEYWORD
  25    jmp_buf jmpbuf;
  26 #endif
  27    png_debug(1, "in png_create_read_struct\n");
  28    if ((png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG)) == NULL)
  29    {
  30       return (png_structp)NULL;
  31    }
  32 #ifdef USE_FAR_KEYWORD
  33    if (setjmp(jmpbuf))
  34 #else
  35    if (setjmp(png_ptr->jmpbuf))
  36 #endif
  37    {
  38       png_free(png_ptr, png_ptr->zbuf);
  39       png_destroy_struct(png_ptr);
  40       return (png_structp)NULL;
  41    }
  42 #ifdef USE_FAR_KEYWORD
  43    png_memcpy(png_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf));
  44 #endif
  45    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
  46
  47    /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
  48     * we must recompile any applications that use any older library version.
  49     * For versions after libpng 1.0, we will be compatible, so we need
  50     * only check the first digit.
  51     */
  52    if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
  53        (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
  54    {
  55       png_error(png_ptr,
  56          "Incompatible libpng version in application and library");
  57    }
  58
  59    /* initialize zbuf - compression buffer */
  60    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
  61    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
  62      (png_uint_32)png_ptr->zbuf_size);
  63    png_ptr->zstream.zalloc = png_zalloc;
  64    png_ptr->zstream.zfree = png_zfree;
  65    png_ptr->zstream.opaque = (voidpf)png_ptr;
  66
  67    switch (inflateInit(&png_ptr->zstream))
  68    {
  69      case Z_OK: /* Do nothing */ break;
  70      case Z_MEM_ERROR:
  71      case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break;
  72      case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error"); break;
  73      default: png_error(png_ptr, "Unknown zlib error");
  74    }
  75
  76    png_ptr->zstream.next_out = png_ptr->zbuf;
  77    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
  78
  79    png_set_read_fn(png_ptr, NULL, NULL);
  80
  81    return (png_ptr);
  82 }
  83
  84 /* Initialize PNG structure for reading, and allocate any memory needed.
  85    This interface is depreciated in favour of the png_create_read_struct(),
  86    and it will eventually disappear. */
  87 void
  88 png_read_init(png_structp png_ptr)
  89 {
  90    jmp_buf tmp_jmp;  /* to save current jump buffer */
  91
  92    png_debug(1, "in png_read_init\n");
  93    /* save jump buffer and error functions */
  94    png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
  95
  96    /* reset all variables to 0 */
  97    png_memset(png_ptr, 0, sizeof (png_struct));
  98
  99    /* restore jump buffer */
 100    png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
 101
 102    /* initialize zbuf - compression buffer */
 103    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
 104    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
 105      (png_uint_32)png_ptr->zbuf_size);
 106    png_ptr->zstream.zalloc = png_zalloc;
 107    png_ptr->zstream.zfree = png_zfree;
 108    png_ptr->zstream.opaque = (voidpf)png_ptr;
 109
 110    switch (inflateInit(&png_ptr->zstream))
 111    {
 112      case Z_OK: /* Do nothing */ break;
 113      case Z_MEM_ERROR:
 114      case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory"); break;
 115      case Z_VERSION_ERROR: png_error(png_ptr, "zlib version"); break;
 116      default: png_error(png_ptr, "Unknown zlib error");
 117    }
 118
 119    png_ptr->zstream.next_out = png_ptr->zbuf;
 120    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 121
 122    png_set_read_fn(png_ptr, NULL, NULL);
 123 }
 124
 125 /* Read the information before the actual image data.  This has been
 126  * changed in v0.90 to allow reading a file that already has the magic
 127  * bytes read from the stream.  You can tell libpng how many bytes have
 128  * been read from the beginning of the stream (up to the maxumum of 8)
 129  * via png_set_sig_bytes(), and we will only check the remaining bytes
 130  * here.  The application can then have access to the signature bytes we
 131  * read if it is determined that this isn't a valid PNG file.
 132  */
 133 void
 134 png_read_info(png_structp png_ptr, png_infop info_ptr)
 135 {
 136    png_debug(1, "in png_read_info\n");
 137    /* save jump buffer and error functions */
 138    /* If we haven't checked all of the PNG signature bytes, do so now. */
 139    if (png_ptr->sig_bytes < 8)
 140    {
 141       png_size_t num_checked = png_ptr->sig_bytes,
 142                  num_to_check = 8 - num_checked;
 143
 144       png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
 145       png_ptr->sig_bytes = 8;
 146
 147       if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 148       {
 149          if (num_checked < 4 &&
 150              png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 151             png_error(png_ptr, "Not a PNG file");
 152          else
 153             png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 154       }
 155    }
 156
 157    for(;;)
 158    {
 159       png_byte chunk_length[4];
 160       png_uint_32 length;
 161
 162       png_read_data(png_ptr, chunk_length, 4);
 163       length = png_get_uint_32(chunk_length);
 164
 165       png_reset_crc(png_ptr);
 166       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 167
 168       png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name);
 169
 170       /* This should be a binary subdivision search or a hash for
 171        * matching the chunk name rather than a linear search.
 172        */
 173       if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 174          png_handle_IHDR(png_ptr, info_ptr, length);
 175       else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 176          png_handle_PLTE(png_ptr, info_ptr, length);
 177       else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 178          png_handle_IEND(png_ptr, info_ptr, length);
 179       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 180       {
 181          if (!(png_ptr->mode & PNG_HAVE_IHDR))
 182             png_error(png_ptr, "Missing IHDR before IDAT");
 183          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 184                   !(png_ptr->mode & PNG_HAVE_PLTE))
 185             png_error(png_ptr, "Missing PLTE before IDAT");
 186
 187          png_ptr->idat_size = length;
 188          png_ptr->mode |= PNG_HAVE_IDAT;
 189          break;
 190       }
 191 #if defined(PNG_READ_bKGD_SUPPORTED)
 192       else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 193          png_handle_bKGD(png_ptr, info_ptr, length);
 194 #endif
 195 #if defined(PNG_READ_cHRM_SUPPORTED)
 196       else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 197          png_handle_cHRM(png_ptr, info_ptr, length);
 198 #endif
 199 #if defined(PNG_READ_gAMA_SUPPORTED)
 200       else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 201          png_handle_gAMA(png_ptr, info_ptr, length);
 202 #endif
 203 #if defined(PNG_READ_hIST_SUPPORTED)
 204       else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 205          png_handle_hIST(png_ptr, info_ptr, length);
 206 #endif
 207 #if defined(PNG_READ_oFFs_SUPPORTED)
 208       else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
 209          png_handle_oFFs(png_ptr, info_ptr, length);
 210 #endif
 211 #if defined(PNG_READ_pCAL_SUPPORTED)
 212       else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
 213          png_handle_pCAL(png_ptr, info_ptr, length);
 214 #endif
 215 #if defined(PNG_READ_pHYs_SUPPORTED)
 216       else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 217          png_handle_pHYs(png_ptr, info_ptr, length);
 218 #endif
 219 #if defined(PNG_READ_sBIT_SUPPORTED)
 220       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 221          png_handle_sBIT(png_ptr, info_ptr, length);
 222 #endif
 223 #if defined(PNG_READ_sRGB_SUPPORTED)
 224       else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
 225          png_handle_sRGB(png_ptr, info_ptr, length);
 226 #endif
 227 #if defined(PNG_READ_tEXt_SUPPORTED)
 228       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 229          png_handle_tEXt(png_ptr, info_ptr, length);
 230 #endif
 231 #if defined(PNG_READ_tIME_SUPPORTED)
 232       else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 233          png_handle_tIME(png_ptr, info_ptr, length);
 234 #endif
 235 #if defined(PNG_READ_tRNS_SUPPORTED)
 236       else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 237          png_handle_tRNS(png_ptr, info_ptr, length);
 238 #endif
 239 #if defined(PNG_READ_zTXt_SUPPORTED)
 240       else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 241          png_handle_zTXt(png_ptr, info_ptr, length);
 242 #endif
 243       else
 244          png_handle_unknown(png_ptr, info_ptr, length);
 245    }
 246 }
 247
 248 /* optional call to update the users info_ptr structure */
 249 void
 250 png_read_update_info(png_structp png_ptr, png_infop info_ptr)
 251 {
 252    png_debug(1, "in png_read_update_info\n");
 253    /* save jump buffer and error functions */
 254    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
 255       png_read_start_row(png_ptr);
 256    png_read_transform_info(png_ptr, info_ptr);
 257 }
 258
 259 /* Initialize palette, background, etc, after transformations
 260  * are set, but before any reading takes place.  This allows
 261  * the user to obtail a gamma corrected palette, for example.
 262  * If the user doesn't call this, we will do it ourselves.
 263  */
 264 void
 265 png_start_read_image(png_structp png_ptr)
 266 {
 267    png_debug(1, "in png_start_read_image\n");
 268    /* save jump buffer and error functions */
 269    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
 270       png_read_start_row(png_ptr);
 271 }
 272
 273 void
 274 png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 275 {
 276    int ret;
 277    png_debug2(1, "in png_read_row (row %d, pass %d)\n",
 278       png_ptr->row_number, png_ptr->pass);
 279    /* save jump buffer and error functions */
 280    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
 281       png_read_start_row(png_ptr);
 282
 283 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 284    /* if interlaced and we do not need a new row, combine row and return */
 285    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 286    {
 287       switch (png_ptr->pass)
 288       {
 289          case 0:
 290             if (png_ptr->row_number & 7)
 291             {
 292                if (dsp_row != NULL)
 293                   png_combine_row(png_ptr, dsp_row,
 294                      png_pass_dsp_mask[png_ptr->pass]);
 295                png_read_finish_row(png_ptr);
 296                return;
 297             }
 298             break;
 299          case 1:
 300             if ((png_ptr->row_number & 7) || png_ptr->width < 5)
 301             {
 302                if (dsp_row != NULL)
 303                   png_combine_row(png_ptr, dsp_row,
 304                      png_pass_dsp_mask[png_ptr->pass]);
 305                png_read_finish_row(png_ptr);
 306                return;
 307             }
 308             break;
 309          case 2:
 310             if ((png_ptr->row_number & 7) != 4)
 311             {
 312                if (dsp_row != NULL && (png_ptr->row_number & 4))
 313                   png_combine_row(png_ptr, dsp_row,
 314                      png_pass_dsp_mask[png_ptr->pass]);
 315                png_read_finish_row(png_ptr);
 316                return;
 317             }
 318             break;
 319          case 3:
 320             if ((png_ptr->row_number & 3) || png_ptr->width < 3)
 321             {
 322                if (dsp_row != NULL)
 323                   png_combine_row(png_ptr, dsp_row,
 324                      png_pass_dsp_mask[png_ptr->pass]);
 325                png_read_finish_row(png_ptr);
 326                return;
 327             }
 328             break;
 329          case 4:
 330             if ((png_ptr->row_number & 3) != 2)
 331             {
 332                if (dsp_row != NULL && (png_ptr->row_number & 2))
 333                   png_combine_row(png_ptr, dsp_row,
 334                      png_pass_dsp_mask[png_ptr->pass]);
 335                png_read_finish_row(png_ptr);
 336                return;
 337             }
 338             break;
 339          case 5:
 340             if ((png_ptr->row_number & 1) || png_ptr->width < 2)
 341             {
 342                if (dsp_row != NULL)
 343                   png_combine_row(png_ptr, dsp_row,
 344                      png_pass_dsp_mask[png_ptr->pass]);
 345                png_read_finish_row(png_ptr);
 346                return;
 347             }
 348             break;
 349          case 6:
 350             if (!(png_ptr->row_number & 1))
 351             {
 352                png_read_finish_row(png_ptr);
 353                return;
 354             }
 355             break;
 356       }
 357    }
 358 #endif
 359
 360    if (!(png_ptr->mode & PNG_HAVE_IDAT))
 361       png_error(png_ptr, "Invalid attempt to read row data");
 362
 363    png_ptr->zstream.next_out = png_ptr->row_buf;
 364    png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 365    do
 366    {
 367       if (!(png_ptr->zstream.avail_in))
 368       {
 369          while (!png_ptr->idat_size)
 370          {
 371             png_byte chunk_length[4];
 372
 373             png_crc_finish(png_ptr, 0);
 374
 375             png_read_data(png_ptr, chunk_length, 4);
 376             png_ptr->idat_size = png_get_uint_32(chunk_length);
 377
 378             png_reset_crc(png_ptr);
 379             png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 380             if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 381                png_error(png_ptr, "Not enough image data");
 382          }
 383          png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
 384          png_ptr->zstream.next_in = png_ptr->zbuf;
 385          if (png_ptr->zbuf_size > png_ptr->idat_size)
 386             png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
 387          png_crc_read(png_ptr, png_ptr->zbuf,
 388             (png_size_t)png_ptr->zstream.avail_in);
 389          png_ptr->idat_size -= png_ptr->zstream.avail_in;
 390       }
 391       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 392       if (ret == Z_STREAM_END)
 393       {
 394          if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
 395             png_ptr->idat_size)
 396             png_error(png_ptr, "Extra compressed data");
 397          png_ptr->mode |= PNG_AFTER_IDAT;
 398          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 399          break;
 400       }
 401       if (ret != Z_OK)
 402          png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
 403                    "Decompression error");
 404
 405    } while (png_ptr->zstream.avail_out);
 406
 407    png_ptr->row_info.color_type = png_ptr->color_type;
 408    png_ptr->row_info.width = png_ptr->iwidth;
 409    png_ptr->row_info.channels = png_ptr->channels;
 410    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
 411    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
 412    {
 413       png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
 414          (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
 415    }
 416
 417    png_read_filter_row(png_ptr, &(png_ptr->row_info),
 418       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
 419       (int)(png_ptr->row_buf[0]));
 420
 421    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
 422       png_ptr->rowbytes + 1);
 423
 424    if (png_ptr->transformations)
 425       png_do_read_transformations(png_ptr);
 426
 427 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 428    /* blow up interlaced rows to full size */
 429    if (png_ptr->interlaced &&
 430       (png_ptr->transformations & PNG_INTERLACE))
 431    {
 432       if (png_ptr->pass < 6)
 433          png_do_read_interlace(&(png_ptr->row_info),
 434             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 435
 436       if (dsp_row != NULL)
 437          png_combine_row(png_ptr, dsp_row,
 438             png_pass_dsp_mask[png_ptr->pass]);
 439       if (row != NULL)
 440          png_combine_row(png_ptr, row,
 441             png_pass_mask[png_ptr->pass]);
 442    }
 443    else
 444 #endif
 445    {
 446       if (row != NULL)
 447          png_combine_row(png_ptr, row, 0xff);
 448       if (dsp_row != NULL)
 449          png_combine_row(png_ptr, dsp_row, 0xff);
 450    }
 451    png_read_finish_row(png_ptr);
 452
 453    if (png_ptr->read_row_fn != NULL)
 454       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
 455 }
 456
 457 /* Read one or more rows of image data.  If the image is interlaced,
 458  * and png_set_interlace_handling() has been called, the rows need to
 459  * contain the contents of the rows from the previous pass.  If the
 460  * image has alpha or transparency, and png_handle_alpha() has been
 461  * called, the rows contents must be initialized to the contents of the
 462  * screen.
 463  *
 464  * "row" holds the actual image, and pixels are placed in it
 465  * as they arrive.  If the image is displayed after each pass, it will
 466  * appear to "sparkle" in.  "display_row" can be used to display a
 467  * "chunky" progressive image, with finer detail added as it becomes
 468  * available.  If you do not want this "chunky" display, you may pass
 469  * NULL for display_row.  If you do not want the sparkle display, and
 470  * you have not called png_handle_alpha(), you may pass NULL for rows.
 471  * If you have called png_handle_alpha(), and the image has either an
 472  * alpha channel or a transparency chunk, you must provide a buffer for
 473  * rows.  In this case, you do not have to provide a display_row buffer
 474  * also, but you may.  If the image is not interlaced, or if you have
 475  * not called png_set_interlace_handling(), the display_row buffer will
 476  * be ignored, so pass NULL to it.
 477  */
 478
 479 void
 480 png_read_rows(png_structp png_ptr, png_bytepp row,
 481    png_bytepp display_row, png_uint_32 num_rows)
 482 {
 483    png_uint_32 i;
 484    png_bytepp rp;
 485    png_bytepp dp;
 486
 487    png_debug(1, "in png_read_rows\n");
 488    /* save jump buffer and error functions */
 489    rp = row;
 490    dp = display_row;
 491    for (i = 0; i < num_rows; i++)
 492    {
 493       png_bytep rptr;
 494       png_bytep dptr;
 495
 496       if (rp != NULL)
 497          rptr = *rp;
 498       else
 499          rptr = NULL;
 500       if (dp != NULL)
 501          dptr = *dp;
 502       else
 503          dptr = NULL;
 504       png_read_row(png_ptr, rptr, dptr);
 505       if (row != NULL)
 506          rp++;
 507       if (display_row != NULL)
 508          dp++;
 509    }
 510 }
 511
 512 /* Read the entire image.  If the image has an alpha channel or a tRNS
 513  * chunk, and you have called png_handle_alpha(), you will need to
 514  * initialize the image to the current image that PNG will be overlaying.
 515  * We set the num_rows again here, in case it was incorrectly set in
 516  * png_read_start_row() by a call to png_read_update_info() or
 517  * png_start_read_image() if png_set_interlace_handling() wasn't called
 518  * prior to either of these functions like it should have been.  You can
 519  * only call this function once.  If you desire to have an image for
 520  * each pass of a interlaced image, use png_read_rows() instead.
 521  */
 522 void
 523 png_read_image(png_structp png_ptr, png_bytepp image)
 524 {
 525    png_uint_32 i;
 526    int pass, j;
 527    png_bytepp rp;
 528
 529    png_debug(1, "in png_read_image\n");
 530    /* save jump buffer and error functions */
 531    pass = png_set_interlace_handling(png_ptr);
 532
 533    png_ptr->num_rows = png_ptr->height; /* Make sure this is set correctly */
 534
 535    for (j = 0; j < pass; j++)
 536    {
 537       rp = image;
 538       for (i = 0; i < png_ptr->height; i++)
 539       {
 540          png_read_row(png_ptr, *rp, NULL);
 541          rp++;
 542       }
 543    }
 544 }
 545
 546 /* Read the end of the PNG file.  Will not read past the end of the
 547  * file, will verify the end is accurate, and will read any comments
 548  * or time information at the end of the file, if info is not NULL.
 549  */
 550 void
 551 png_read_end(png_structp png_ptr, png_infop info_ptr)
 552 {
 553    png_byte chunk_length[4];
 554    png_uint_32 length;
 555
 556    png_debug(1, "in png_read_end\n");
 557    /* save jump buffer and error functions */
 558    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
 559
 560    do
 561    {
 562       png_read_data(png_ptr, chunk_length, 4);
 563       length = png_get_uint_32(chunk_length);
 564
 565       png_reset_crc(png_ptr);
 566       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 567
 568       png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name);
 569
 570       if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 571          png_handle_IHDR(png_ptr, info_ptr, length);
 572       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 573       {
 574          /* Zero length IDATs are legal after the last IDAT has been
 575           * read, but not after other chunks have been read.
 576           */
 577          if (length > 0 || png_ptr->mode & PNG_AFTER_IDAT)
 578             png_error(png_ptr, "Too many IDAT's found");
 579          else
 580             png_crc_finish(png_ptr, 0);
 581       }
 582       else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 583          png_handle_PLTE(png_ptr, info_ptr, length);
 584       else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 585          png_handle_IEND(png_ptr, info_ptr, length);
 586 #if defined(PNG_READ_bKGD_SUPPORTED)
 587       else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 588          png_handle_bKGD(png_ptr, info_ptr, length);
 589 #endif
 590 #if defined(PNG_READ_cHRM_SUPPORTED)
 591       else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 592          png_handle_cHRM(png_ptr, info_ptr, length);
 593 #endif
 594 #if defined(PNG_READ_gAMA_SUPPORTED)
 595       else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 596          png_handle_gAMA(png_ptr, info_ptr, length);
 597 #endif
 598 #if defined(PNG_READ_hIST_SUPPORTED)
 599       else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 600          png_handle_hIST(png_ptr, info_ptr, length);
 601 #endif
 602 #if defined(PNG_READ_oFFs_SUPPORTED)
 603       else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
 604          png_handle_oFFs(png_ptr, info_ptr, length);
 605 #endif
 606 #if defined(PNG_READ_pCAL_SUPPORTED)
 607       else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
 608          png_handle_pCAL(png_ptr, info_ptr, length);
 609 #endif
 610 #if defined(PNG_READ_pHYs_SUPPORTED)
 611       else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 612          png_handle_pHYs(png_ptr, info_ptr, length);
 613 #endif
 614 #if defined(PNG_READ_sBIT_SUPPORTED)
 615       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 616          png_handle_sBIT(png_ptr, info_ptr, length);
 617 #endif
 618 #if defined(PNG_READ_sRGB_SUPPORTED)
 619       else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
 620          png_handle_sRGB(png_ptr, info_ptr, length);
 621 #endif
 622 #if defined(PNG_READ_tEXt_SUPPORTED)
 623       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 624          png_handle_tEXt(png_ptr, info_ptr, length);
 625 #endif
 626 #if defined(PNG_READ_tIME_SUPPORTED)
 627       else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 628          png_handle_tIME(png_ptr, info_ptr, length);
 629 #endif
 630 #if defined(PNG_READ_tRNS_SUPPORTED)
 631       else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 632          png_handle_tRNS(png_ptr, info_ptr, length);
 633 #endif
 634 #if defined(PNG_READ_zTXt_SUPPORTED)
 635       else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 636          png_handle_zTXt(png_ptr, info_ptr, length);
 637 #endif
 638       else
 639          png_handle_unknown(png_ptr, info_ptr, length);
 640    } while (!(png_ptr->mode & PNG_HAVE_IEND));
 641 }
 642
 643 /* free all memory used by the read */
 644 void
 645 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 646    png_infopp end_info_ptr_ptr)
 647 {
 648    png_structp png_ptr = NULL;
 649    png_infop info_ptr = NULL, end_info_ptr = NULL;
 650
 651    png_debug(1, "in png_destroy_read_struct\n");
 652    /* save jump buffer and error functions */
 653    if (png_ptr_ptr != NULL)
 654       png_ptr = *png_ptr_ptr;
 655
 656    if (info_ptr_ptr != NULL)
 657       info_ptr = *info_ptr_ptr;
 658
 659    if (end_info_ptr_ptr != NULL)
 660       end_info_ptr = *end_info_ptr_ptr;
 661
 662    png_read_destroy(png_ptr, info_ptr, end_info_ptr);
 663
 664    if (info_ptr != NULL)
 665    {
 666 #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
 667       png_free(png_ptr, info_ptr->text);
 668 #endif
 669       png_destroy_struct((png_voidp)info_ptr);
 670       *info_ptr_ptr = (png_infop)NULL;
 671    }
 672
 673    if (end_info_ptr != NULL)
 674    {
 675 #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
 676       png_free(png_ptr, end_info_ptr->text);
 677 #endif
 678       png_destroy_struct((png_voidp)end_info_ptr);
 679       *end_info_ptr_ptr = (png_infop)NULL;
 680    }
 681
 682    if (png_ptr != NULL)
 683    {
 684       png_destroy_struct((png_voidp)png_ptr);
 685       *png_ptr_ptr = (png_structp)NULL;
 686    }
 687 }
 688
 689 /* free all memory used by the read (old method) */
 690 void
 691 png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr)
 692 {
 693    jmp_buf tmp_jmp;
 694    png_error_ptr error_fn;
 695    png_error_ptr warning_fn;
 696    png_voidp error_ptr;
 697
 698    png_debug(1, "in png_read_destroy\n");
 699    /* save jump buffer and error functions */
 700    if (info_ptr != NULL)
 701       png_info_destroy(png_ptr, info_ptr);
 702
 703    if (end_info_ptr != NULL)
 704       png_info_destroy(png_ptr, end_info_ptr);
 705
 706    png_free(png_ptr, png_ptr->zbuf);
 707    png_free(png_ptr, png_ptr->row_buf);
 708    png_free(png_ptr, png_ptr->prev_row);
 709 #if defined(PNG_READ_DITHER_SUPPORTED)
 710    png_free(png_ptr, png_ptr->palette_lookup);
 711    png_free(png_ptr, png_ptr->dither_index);
 712 #endif
 713 #if defined(PNG_READ_GAMMA_SUPPORTED)
 714    png_free(png_ptr, png_ptr->gamma_table);
 715 #endif
 716 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
 717    png_free(png_ptr, png_ptr->gamma_from_1);
 718    png_free(png_ptr, png_ptr->gamma_to_1);
 719 #endif
 720    if (png_ptr->flags & PNG_FLAG_FREE_PALETTE)
 721       png_zfree(png_ptr, png_ptr->palette);
 722    if (png_ptr->flags & PNG_FLAG_FREE_TRANS)
 723       png_free(png_ptr, png_ptr->trans);
 724 #if defined(PNG_READ_hIST_SUPPORTED)
 725    if (png_ptr->flags & PNG_FLAG_FREE_HIST)
 726       png_free(png_ptr, png_ptr->hist);
 727 #endif
 728 #if defined(PNG_READ_GAMMA_SUPPORTED)
 729    if (png_ptr->gamma_16_table != NULL)
 730    {
 731       int i;
 732       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
 733       {
 734          png_free(png_ptr, png_ptr->gamma_16_table[i]);
 735       }
 736    }
 737 #endif
 738 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
 739    png_free(png_ptr, png_ptr->gamma_16_table);
 740    if (png_ptr->gamma_16_from_1 != NULL)
 741    {
 742       int i;
 743       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
 744       {
 745          png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
 746       }
 747    }
 748    png_free(png_ptr, png_ptr->gamma_16_from_1);
 749    if (png_ptr->gamma_16_to_1 != NULL)
 750    {
 751       int i;
 752       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
 753       {
 754          png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
 755       }
 756    }
 757    png_free(png_ptr, png_ptr->gamma_16_to_1);
 758 #endif
 759
 760    inflateEnd(&png_ptr->zstream);
 761 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 762    png_free(png_ptr, png_ptr->save_buffer);
 763 #endif
 764
 765    /* Save the important info out of the png_struct, in case it is
 766     * being used again.
 767     */
 768    png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
 769
 770    error_fn = png_ptr->error_fn;
 771    warning_fn = png_ptr->warning_fn;
 772    error_ptr = png_ptr->error_ptr;
 773
 774    png_memset(png_ptr, 0, sizeof (png_struct));
 775
 776    png_ptr->error_fn = error_fn;
 777    png_ptr->warning_fn = warning_fn;
 778    png_ptr->error_ptr = error_ptr;
 779
 780    png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
 781 }
 782
 783 void
 784 png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
 785 {
 786    png_ptr->read_row_fn = read_row_fn;
 787 }