src/png/pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   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
  12 #define PNG_INTERNAL
  13 #include "png.h"
  14
  15 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  16
  17 void
  18 png_process_data(png_structp png_ptr, png_infop info_ptr,
  19    png_bytep buffer, png_size_t buffer_size)
  20 {
  21    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  22
  23    while (png_ptr->buffer_size)
  24    {
  25       png_process_some_data(png_ptr, info_ptr);
  26    }
  27 }
  28
  29 /* What we do with the incoming data depends on what we were previously
  30  * doing before we ran out of data...
  31  */
  32 void
  33 png_process_some_data(png_structp png_ptr, png_infop info_ptr)
  34 {
  35    switch (png_ptr->process_mode)
  36    {
  37       case PNG_READ_SIG_MODE:
  38       {
  39          png_push_read_sig(png_ptr, info_ptr);
  40          break;
  41       }
  42       case PNG_READ_CHUNK_MODE:
  43       {
  44          png_push_read_chunk(png_ptr, info_ptr);
  45          break;
  46       }
  47       case PNG_READ_IDAT_MODE:
  48       {
  49          png_push_read_IDAT(png_ptr);
  50          break;
  51       }
  52 #if defined(PNG_READ_tEXt_SUPPORTED)
  53       case PNG_READ_tEXt_MODE:
  54       {
  55          png_push_read_tEXt(png_ptr, info_ptr);
  56          break;
  57       }
  58 #endif
  59 #if defined(PNG_READ_zTXt_SUPPORTED)
  60       case PNG_READ_zTXt_MODE:
  61       {
  62          png_push_read_zTXt(png_ptr, info_ptr);
  63          break;
  64       }
  65 #endif
  66       case PNG_SKIP_MODE:
  67       {
  68          png_push_crc_finish(png_ptr);
  69          break;
  70       }
  71       default:
  72       {
  73          png_ptr->buffer_size = 0;
  74          break;
  75       }
  76    }
  77 }
  78
  79 /* Read any remaining signature bytes from the stream and compare them with
  80  * the correct PNG signature.  It is possible that this routine is called
  81  * with bytes already read from the signature, whether because they have been
  82  * checked by the calling application, or from multiple calls to this routine.
  83  */
  84 void
  85 png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
  86 {
  87    png_size_t num_checked = png_ptr->sig_bytes,
  88              num_to_check = 8 - num_checked;
  89
  90    if (png_ptr->buffer_size < num_to_check)
  91    {
  92       num_to_check = png_ptr->buffer_size;
  93    }
  94
  95    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
  96       num_to_check);
  97    png_ptr->sig_bytes += num_to_check;
  98
  99    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 100    {
 101       if (num_checked < 4 &&
 102           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 103          png_error(png_ptr, "Not a PNG file");
 104       else
 105          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 106    }
 107    else
 108    {
 109       if (png_ptr->sig_bytes >= 8)
 110       {
 111          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 112       }
 113    }
 114 }
 115
 116 void
 117 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 118 {
 119    /* First we make sure we have enough data for the 4 byte chunk name
 120     * and the 4 byte chunk length before proceeding with decoding the
 121     * chunk data.  To fully decode each of these chunks, we also make
 122     * sure we have enough data in the buffer for the 4 byte CRC at the
 123     * end of every chunk (except IDAT, which is handled separately).
 124     */
 125    if (!(png_ptr->flags & PNG_FLAG_HAVE_CHUNK_HEADER))
 126    {
 127       png_byte chunk_length[4];
 128
 129       if (png_ptr->buffer_size < 8)
 130       {
 131          png_push_save_buffer(png_ptr);
 132          return;
 133       }
 134
 135       png_push_fill_buffer(png_ptr, chunk_length, 4);
 136       png_ptr->push_length = png_get_uint_32(chunk_length);
 137       png_reset_crc(png_ptr);
 138       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 139       png_ptr->flags |= PNG_FLAG_HAVE_CHUNK_HEADER;
 140    }
 141
 142    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 143    {
 144       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 145       {
 146          png_push_save_buffer(png_ptr);
 147          return;
 148       }
 149
 150       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 151    }
 152    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 153    {
 154       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 155       {
 156          png_push_save_buffer(png_ptr);
 157          return;
 158       }
 159
 160       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 161    }
 162    else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 163    {
 164       /* If we reach an IDAT chunk, this means we have read all of the
 165        * header chunks, and we can start reading the image (or if this
 166        * is called after the image has been read - we have an error).
 167        */
 168       if (png_ptr->mode & PNG_HAVE_IDAT)
 169       {
 170          if (png_ptr->push_length == 0)
 171             return;
 172
 173          if (png_ptr->mode & PNG_AFTER_IDAT)
 174             png_error(png_ptr, "Too many IDAT's found");
 175       }
 176
 177       png_ptr->idat_size = png_ptr->push_length;
 178       png_ptr->mode |= PNG_HAVE_IDAT;
 179       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 180       png_push_have_info(png_ptr, info_ptr);
 181       png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 182       png_ptr->zstream.next_out = png_ptr->row_buf;
 183       return;
 184    }
 185    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 186    {
 187       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 188       {
 189          png_push_save_buffer(png_ptr);
 190          return;
 191       }
 192
 193       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 194       png_ptr->process_mode = PNG_READ_DONE_MODE;
 195       png_push_have_end(png_ptr, info_ptr);
 196    }
 197 #if defined(PNG_READ_gAMA_SUPPORTED)
 198    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 199    {
 200       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 201       {
 202          png_push_save_buffer(png_ptr);
 203          return;
 204       }
 205
 206       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 207    }
 208 #endif
 209 #if defined(PNG_READ_sBIT_SUPPORTED)
 210    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 211    {
 212       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 213       {
 214          png_push_save_buffer(png_ptr);
 215          return;
 216       }
 217
 218       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 219    }
 220 #endif
 221 #if defined(PNG_READ_cHRM_SUPPORTED)
 222    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 223    {
 224       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 225       {
 226          png_push_save_buffer(png_ptr);
 227          return;
 228       }
 229
 230       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 231    }
 232 #endif
 233 #if defined(PNG_READ_sRGB_SUPPORTED)
 234    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
 235    {
 236       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 237       {
 238          png_push_save_buffer(png_ptr);
 239          return;
 240       }
 241
 242       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 243    }
 244 #endif
 245 #if defined(PNG_READ_tRNS_SUPPORTED)
 246    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 247    {
 248       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 249       {
 250          png_push_save_buffer(png_ptr);
 251          return;
 252       }
 253
 254       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 255    }
 256 #endif
 257 #if defined(PNG_READ_bKGD_SUPPORTED)
 258    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 259    {
 260       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 261       {
 262          png_push_save_buffer(png_ptr);
 263          return;
 264       }
 265
 266       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 267    }
 268 #endif
 269 #if defined(PNG_READ_hIST_SUPPORTED)
 270    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 271    {
 272       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 273       {
 274          png_push_save_buffer(png_ptr);
 275          return;
 276       }
 277
 278       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 279    }
 280 #endif
 281 #if defined(PNG_READ_pHYs_SUPPORTED)
 282    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 283    {
 284       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 285       {
 286          png_push_save_buffer(png_ptr);
 287          return;
 288       }
 289
 290       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 291    }
 292 #endif
 293 #if defined(PNG_READ_oFFs_SUPPORTED)
 294    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
 295    {
 296       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 297       {
 298          png_push_save_buffer(png_ptr);
 299          return;
 300       }
 301
 302       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 303    }
 304 #endif
 305 #if defined(PNG_READ_pCAL_SUPPORTED)
 306    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
 307    {
 308       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 309       {
 310          png_push_save_buffer(png_ptr);
 311          return;
 312       }
 313
 314       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 315    }
 316 #endif
 317 #if defined(PNG_READ_tIME_SUPPORTED)
 318    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 319    {
 320       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 321       {
 322          png_push_save_buffer(png_ptr);
 323          return;
 324       }
 325
 326       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 327    }
 328 #endif
 329 #if defined(PNG_READ_tEXt_SUPPORTED)
 330    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 331    {
 332       png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 333    }
 334 #endif
 335 #if defined(PNG_READ_zTXt_SUPPORTED)
 336    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 337    {
 338       png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 339    }
 340 #endif
 341    else
 342    {
 343       png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 344    }
 345
 346    png_ptr->flags &= ~PNG_FLAG_HAVE_CHUNK_HEADER;
 347 }
 348
 349 void
 350 png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
 351 {
 352    png_ptr->process_mode = PNG_SKIP_MODE;
 353    png_ptr->skip_length = skip;
 354 }
 355
 356 void
 357 png_push_crc_finish(png_structp png_ptr)
 358 {
 359    if (png_ptr->skip_length && png_ptr->save_buffer_size)
 360    {
 361       png_size_t save_size;
 362
 363       if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
 364          save_size = (png_size_t)png_ptr->skip_length;
 365       else
 366          save_size = png_ptr->save_buffer_size;
 367
 368       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 369
 370       png_ptr->skip_length -= save_size;
 371       png_ptr->buffer_size -= save_size;
 372       png_ptr->save_buffer_size -= save_size;
 373       png_ptr->save_buffer_ptr += save_size;
 374    }
 375    if (png_ptr->skip_length && png_ptr->current_buffer_size)
 376    {
 377       png_size_t save_size;
 378
 379       if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
 380          save_size = (png_size_t)png_ptr->skip_length;
 381       else
 382          save_size = png_ptr->current_buffer_size;
 383
 384       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 385
 386       png_ptr->skip_length -= save_size;
 387       png_ptr->buffer_size -= save_size;
 388       png_ptr->current_buffer_size -= save_size;
 389       png_ptr->current_buffer_ptr += save_size;
 390    }
 391    if (!png_ptr->skip_length)
 392    {
 393       if (png_ptr->buffer_size < 4)
 394       {
 395          png_push_save_buffer(png_ptr);
 396          return;
 397       }
 398
 399       png_crc_finish(png_ptr, 0);
 400       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 401    }
 402 }
 403
 404 void
 405 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 406 {
 407    png_bytep ptr;
 408
 409    ptr = buffer;
 410    if (png_ptr->save_buffer_size)
 411    {
 412       png_size_t save_size;
 413
 414       if (length < png_ptr->save_buffer_size)
 415          save_size = length;
 416       else
 417          save_size = png_ptr->save_buffer_size;
 418
 419       png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 420       length -= save_size;
 421       ptr += save_size;
 422       png_ptr->buffer_size -= save_size;
 423       png_ptr->save_buffer_size -= save_size;
 424       png_ptr->save_buffer_ptr += save_size;
 425    }
 426    if (length && png_ptr->current_buffer_size)
 427    {
 428       png_size_t save_size;
 429
 430       if (length < png_ptr->current_buffer_size)
 431          save_size = length;
 432       else
 433          save_size = png_ptr->current_buffer_size;
 434
 435       png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 436       png_ptr->buffer_size -= save_size;
 437       png_ptr->current_buffer_size -= save_size;
 438       png_ptr->current_buffer_ptr += save_size;
 439    }
 440 }
 441
 442 void
 443 png_push_save_buffer(png_structp png_ptr)
 444 {
 445    if (png_ptr->save_buffer_size)
 446    {
 447       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 448       {
 449          png_size_t i;
 450          png_bytep sp;
 451          png_bytep dp;
 452
 453          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 454             i < png_ptr->save_buffer_size;
 455             i++, sp++, dp++)
 456          {
 457             *dp = *sp;
 458          }
 459       }
 460    }
 461    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 462       png_ptr->save_buffer_max)
 463    {
 464       png_size_t new_max;
 465       png_bytep old_buffer;
 466
 467       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 468       old_buffer = png_ptr->save_buffer;
 469       png_ptr->save_buffer = (png_bytep)png_malloc(png_ptr,
 470          (png_uint_32)new_max);
 471       png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 472       png_free(png_ptr, old_buffer);
 473       png_ptr->save_buffer_max = new_max;
 474    }
 475    if (png_ptr->current_buffer_size)
 476    {
 477       png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 478          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 479       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 480       png_ptr->current_buffer_size = 0;
 481    }
 482    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 483    png_ptr->buffer_size = 0;
 484 }
 485
 486 void
 487 png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 488    png_size_t buffer_length)
 489 {
 490    png_ptr->current_buffer = buffer;
 491    png_ptr->current_buffer_size = buffer_length;
 492    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 493    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 494 }
 495
 496 void
 497 png_push_read_IDAT(png_structp png_ptr)
 498 {
 499    if (!(png_ptr->flags & PNG_FLAG_HAVE_CHUNK_HEADER))
 500    {
 501       png_byte chunk_length[4];
 502
 503       if (png_ptr->buffer_size < 8)
 504       {
 505          png_push_save_buffer(png_ptr);
 506          return;
 507       }
 508
 509       png_push_fill_buffer(png_ptr, chunk_length, 4);
 510       png_ptr->push_length = png_get_uint_32(chunk_length);
 511
 512       png_reset_crc(png_ptr);
 513       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 514       png_ptr->flags |= PNG_FLAG_HAVE_CHUNK_HEADER;
 515
 516       if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 517       {
 518          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 519          if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 520             png_error(png_ptr, "Not enough compressed data");
 521          return;
 522       }
 523
 524       png_ptr->idat_size = png_ptr->push_length;
 525    }
 526    if (png_ptr->idat_size && png_ptr->save_buffer_size)
 527    {
 528       png_size_t save_size;
 529
 530       if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
 531       {
 532          save_size = (png_size_t)png_ptr->idat_size;
 533          /* check for overflow */
 534          if((png_uint_32)save_size != png_ptr->idat_size)
 535             png_error(png_ptr, "save_size overflowed in pngpread");
 536       }
 537       else
 538          save_size = png_ptr->save_buffer_size;
 539
 540       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 541       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 542
 543       png_ptr->idat_size -= save_size;
 544       png_ptr->buffer_size -= save_size;
 545       png_ptr->save_buffer_size -= save_size;
 546       png_ptr->save_buffer_ptr += save_size;
 547    }
 548    if (png_ptr->idat_size && png_ptr->current_buffer_size)
 549    {
 550       png_size_t save_size;
 551
 552       if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
 553       {
 554          save_size = (png_size_t)png_ptr->idat_size;
 555          /* check for overflow */
 556          if((png_uint_32)save_size != png_ptr->idat_size)
 557             png_error(png_ptr, "save_size overflowed in pngpread");
 558       }
 559       else
 560          save_size = png_ptr->current_buffer_size;
 561
 562       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 563       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 564
 565       png_ptr->idat_size -= save_size;
 566       png_ptr->buffer_size -= save_size;
 567       png_ptr->current_buffer_size -= save_size;
 568       png_ptr->current_buffer_ptr += save_size;
 569    }
 570    if (!png_ptr->idat_size)
 571    {
 572       if (png_ptr->buffer_size < 4)
 573       {
 574          png_push_save_buffer(png_ptr);
 575          return;
 576       }
 577
 578       png_crc_finish(png_ptr, 0);
 579       png_ptr->flags &= ~PNG_FLAG_HAVE_CHUNK_HEADER;
 580    }
 581 }
 582
 583 void
 584 png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 585    png_size_t buffer_length)
 586 {
 587    int ret;
 588
 589    if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
 590       png_error(png_ptr, "Extra compression data");
 591
 592    png_ptr->zstream.next_in = buffer;
 593    png_ptr->zstream.avail_in = (uInt)buffer_length;
 594    for(;;)
 595    {
 596       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 597       if (ret == Z_STREAM_END)
 598       {
 599          if (png_ptr->zstream.avail_in)
 600             png_error(png_ptr, "Extra compressed data");
 601          if (!(png_ptr->zstream.avail_out))
 602          {
 603             png_push_process_row(png_ptr);
 604          }
 605
 606          png_ptr->mode |= PNG_AFTER_IDAT;
 607          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 608          break;
 609       }
 610       else if (ret == Z_BUF_ERROR)
 611          break;
 612       else if (ret != Z_OK)
 613          png_error(png_ptr, "Decompression Error");
 614       if (!(png_ptr->zstream.avail_out))
 615       {
 616          png_push_process_row(png_ptr);
 617          png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 618          png_ptr->zstream.next_out = png_ptr->row_buf;
 619       }
 620       else
 621          break;
 622    }
 623 }
 624
 625 void
 626 png_push_process_row(png_structp png_ptr)
 627 {
 628    png_ptr->row_info.color_type = png_ptr->color_type;
 629    png_ptr->row_info.width = png_ptr->iwidth;
 630    png_ptr->row_info.channels = png_ptr->channels;
 631    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
 632    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
 633
 634    png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
 635       (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
 636
 637    png_read_filter_row(png_ptr, &(png_ptr->row_info),
 638       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
 639       (int)(png_ptr->row_buf[0]));
 640
 641    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
 642       png_ptr->rowbytes + 1);
 643
 644    if (png_ptr->transformations)
 645       png_do_read_transformations(png_ptr);
 646
 647 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 648    /* blow up interlaced rows to full size */
 649    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 650    {
 651       if (png_ptr->pass < 6)
 652          png_do_read_interlace(&(png_ptr->row_info),
 653             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 654
 655       switch (png_ptr->pass)
 656       {
 657          case 0:
 658          {
 659             int i;
 660             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 661             {
 662                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 663                png_read_push_finish_row(png_ptr);
 664             }
 665             break;
 666          }
 667          case 1:
 668          {
 669             int i;
 670             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
 671             {
 672                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 673                png_read_push_finish_row(png_ptr);
 674             }
 675             if (png_ptr->pass == 2)
 676             {
 677                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 678                {
 679                   png_push_have_row(png_ptr, NULL);
 680                   png_read_push_finish_row(png_ptr);
 681                }
 682             }
 683             break;
 684          }
 685          case 2:
 686          {
 687             int i;
 688             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 689             {
 690                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 691                png_read_push_finish_row(png_ptr);
 692             }
 693             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 694             {
 695                png_push_have_row(png_ptr, NULL);
 696                png_read_push_finish_row(png_ptr);
 697             }
 698             break;
 699          }
 700          case 3:
 701          {
 702             int i;
 703             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
 704             {
 705                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 706                png_read_push_finish_row(png_ptr);
 707             }
 708             if (png_ptr->pass == 4)
 709             {
 710                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 711                {
 712                   png_push_have_row(png_ptr, NULL);
 713                   png_read_push_finish_row(png_ptr);
 714                }
 715             }
 716             break;
 717          }
 718          case 4:
 719          {
 720             int i;
 721             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 722             {
 723                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 724                png_read_push_finish_row(png_ptr);
 725             }
 726             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 727             {
 728                png_push_have_row(png_ptr, NULL);
 729                png_read_push_finish_row(png_ptr);
 730             }
 731             break;
 732          }
 733          case 5:
 734          {
 735             int i;
 736             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
 737             {
 738                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 739                png_read_push_finish_row(png_ptr);
 740             }
 741             if (png_ptr->pass == 6)
 742             {
 743                png_push_have_row(png_ptr, NULL);
 744                png_read_push_finish_row(png_ptr);
 745             }
 746             break;
 747          }
 748          case 6:
 749          {
 750             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 751             png_read_push_finish_row(png_ptr);
 752             if (png_ptr->pass != 6)
 753                break;
 754             png_push_have_row(png_ptr, NULL);
 755             png_read_push_finish_row(png_ptr);
 756          }
 757       }
 758    }
 759    else
 760 #endif
 761    {
 762       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 763       png_read_push_finish_row(png_ptr);
 764    }
 765 }
 766
 767 void
 768 png_read_push_finish_row(png_structp png_ptr)
 769 {
 770    png_ptr->row_number++;
 771    if (png_ptr->row_number < png_ptr->num_rows)
 772       return;
 773
 774    if (png_ptr->interlaced)
 775    {
 776       png_ptr->row_number = 0;
 777       png_memset_check(png_ptr, png_ptr->prev_row, 0,
 778          png_ptr->rowbytes + 1);
 779       do
 780       {
 781          png_ptr->pass++;
 782          if (png_ptr->pass >= 7)
 783             break;
 784          png_ptr->iwidth = (png_ptr->width +
 785             png_pass_inc[png_ptr->pass] - 1 -
 786             png_pass_start[png_ptr->pass]) /
 787             png_pass_inc[png_ptr->pass];
 788
 789          png_ptr->irowbytes = ((png_ptr->iwidth *
 790             png_ptr->pixel_depth + 7) >> 3) + 1;
 791
 792          if (!(png_ptr->transformations & PNG_INTERLACE))
 793          {
 794             png_ptr->num_rows = (png_ptr->height +
 795                png_pass_yinc[png_ptr->pass] - 1 -
 796                png_pass_ystart[png_ptr->pass]) /
 797                png_pass_yinc[png_ptr->pass];
 798             if (!(png_ptr->num_rows))
 799                continue;
 800          }
 801          if (png_ptr->transformations & PNG_INTERLACE)
 802             break;
 803       } while (png_ptr->iwidth == 0);
 804    }
 805 }
 806
 807 #if defined(PNG_READ_tEXt_SUPPORTED)
 808 void
 809 png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 810 {
 811    if (png_ptr->mode == PNG_BEFORE_IHDR || png_ptr->mode & PNG_HAVE_IEND)
 812       {
 813          png_error(png_ptr, "Out of place tEXt");
 814          /* to quiet some compiler warnings */
 815          if(info_ptr == NULL) return;
 816       }
 817
 818 #ifdef PNG_MAX_MALLOC_64K
 819    png_ptr->skip_length = 0;  /* This may not be necessary */
 820
 821    if (length > (png_uint_32)65535L) /* Can't hold the entire string in memory */
 822    {
 823       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
 824       png_ptr->skip_length = length - (png_uint_32)65535L;
 825       length = (png_uint_32)65535L;
 826    }
 827 #endif
 828
 829    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
 830          (png_uint_32)(length+1));
 831    png_ptr->current_text[length] = '\0';
 832    png_ptr->current_text_ptr = png_ptr->current_text;
 833    png_ptr->current_text_size = (png_size_t)length;
 834    png_ptr->current_text_left = (png_size_t)length;
 835    png_ptr->process_mode = PNG_READ_tEXt_MODE;
 836 }
 837
 838 void
 839 png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
 840 {
 841    if (png_ptr->buffer_size && png_ptr->current_text_left)
 842    {
 843       png_size_t text_size;
 844
 845       if (png_ptr->buffer_size < png_ptr->current_text_left)
 846          text_size = png_ptr->buffer_size;
 847       else
 848          text_size = png_ptr->current_text_left;
 849       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
 850       png_ptr->current_text_left -= text_size;
 851       png_ptr->current_text_ptr += text_size;
 852    }
 853    if (!(png_ptr->current_text_left))
 854    {
 855       png_textp text_ptr;
 856       png_charp text;
 857       png_charp key;
 858
 859       if (png_ptr->buffer_size < 4)
 860       {
 861          png_push_save_buffer(png_ptr);
 862          return;
 863       }
 864
 865       png_push_crc_finish(png_ptr);
 866
 867 #if defined(PNG_MAX_MALLOC_64K)
 868       if (png_ptr->skip_length)
 869          return;
 870 #endif
 871
 872       key = png_ptr->current_text;
 873       png_ptr->current_text = 0;
 874
 875       for (text = key; *text; text++)
 876          /* empty loop */ ;
 877
 878       if (text != key + png_ptr->current_text_size)
 879          text++;
 880
 881       text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
 882       text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
 883       text_ptr->key = key;
 884       text_ptr->text = text;
 885
 886       png_set_text(png_ptr, info_ptr, text_ptr, 1);
 887
 888       png_free(png_ptr, text_ptr);
 889    }
 890 }
 891 #endif
 892
 893 #if defined(PNG_READ_zTXt_SUPPORTED)
 894 void
 895 png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 896 {
 897    if (png_ptr->mode == PNG_BEFORE_IHDR || png_ptr->mode & PNG_HAVE_IEND)
 898       {
 899          png_error(png_ptr, "Out of place zTXt");
 900          /* to quiet some compiler warnings */
 901          if(info_ptr == NULL) return;
 902       }
 903
 904 #ifdef PNG_MAX_MALLOC_64K
 905    /* We can't handle zTXt chunks > 64K, since we don't have enough space
 906     * to be able to store the uncompressed data.  Actually, the threshold
 907     * is probably around 32K, but it isn't as definite as 64K is.
 908     */
 909    if (length > (png_uint_32)65535L)
 910    {
 911       png_warning(png_ptr, "zTXt chunk too large to fit in memory");
 912       png_push_crc_skip(png_ptr, length);
 913       return;
 914    }
 915 #endif
 916
 917    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
 918        (png_uint_32)(length+1));
 919    png_ptr->current_text[length] = '\0';
 920    png_ptr->current_text_ptr = png_ptr->current_text;
 921    png_ptr->current_text_size = (png_size_t)length;
 922    png_ptr->current_text_left = (png_size_t)length;
 923    png_ptr->process_mode = PNG_READ_zTXt_MODE;
 924 }
 925
 926 void
 927 png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
 928 {
 929    if (png_ptr->buffer_size && png_ptr->current_text_left)
 930    {
 931       png_size_t text_size;
 932
 933       if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left)
 934          text_size = png_ptr->buffer_size;
 935       else
 936          text_size = png_ptr->current_text_left;
 937       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
 938       png_ptr->current_text_left -= text_size;
 939       png_ptr->current_text_ptr += text_size;
 940    }
 941    if (!(png_ptr->current_text_left))
 942    {
 943       png_textp text_ptr;
 944       png_charp text;
 945       png_charp key;
 946       int ret;
 947       png_size_t text_size, key_size;
 948
 949       if (png_ptr->buffer_size < 4)
 950       {
 951          png_push_save_buffer(png_ptr);
 952          return;
 953       }
 954
 955       png_push_crc_finish(png_ptr);
 956
 957       key = png_ptr->current_text;
 958       png_ptr->current_text = 0;
 959
 960       for (text = key; *text; text++)
 961          /* empty loop */ ;
 962
 963       /* zTXt can't have zero text */
 964       if (text == key + png_ptr->current_text_size)
 965       {
 966          png_free(png_ptr, key);
 967          return;
 968       }
 969
 970       text++;
 971
 972       if (*text != PNG_TEXT_COMPRESSION_zTXt) /* check compression byte */
 973       {
 974          png_free(png_ptr, key);
 975          return;
 976       }
 977
 978       text++;
 979
 980       png_ptr->zstream.next_in = (png_bytep )text;
 981       png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size -
 982          (text - key));
 983       png_ptr->zstream.next_out = png_ptr->zbuf;
 984       png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 985
 986       key_size = text - key;
 987       text_size = 0;
 988       text = NULL;
 989       ret = Z_STREAM_END;
 990
 991       while (png_ptr->zstream.avail_in)
 992       {
 993          ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 994          if (ret != Z_OK && ret != Z_STREAM_END)
 995          {
 996             inflateReset(&png_ptr->zstream);
 997             png_ptr->zstream.avail_in = 0;
 998             png_free(png_ptr, key);
 999             png_free(png_ptr, text);
1000             return;
1001          }
1002          if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END)
1003          {
1004             if (text == NULL)
1005             {
1006                text = (png_charp)png_malloc(png_ptr,
1007                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out +
1008                      key_size + 1));
1009                png_memcpy(text + key_size, png_ptr->zbuf,
1010                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1011                png_memcpy(text, key, key_size);
1012                text_size = key_size + png_ptr->zbuf_size -
1013                   png_ptr->zstream.avail_out;
1014                *(text + text_size) = '\0';
1015             }
1016             else
1017             {
1018                png_charp tmp;
1019
1020                tmp = text;
1021                text = (png_charp)png_malloc(png_ptr, text_size +
1022                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out
1023                    + 1));
1024                png_memcpy(text, tmp, text_size);
1025                png_free(png_ptr, tmp);
1026                png_memcpy(text + text_size, png_ptr->zbuf,
1027                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1028                text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
1029                *(text + text_size) = '\0';
1030             }
1031             if (ret != Z_STREAM_END)
1032             {
1033                png_ptr->zstream.next_out = png_ptr->zbuf;
1034                png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1035             }
1036          }
1037          else
1038          {
1039             break;
1040          }
1041
1042          if (ret == Z_STREAM_END)
1043             break;
1044       }
1045
1046       inflateReset(&png_ptr->zstream);
1047       png_ptr->zstream.avail_in = 0;
1048
1049       if (ret != Z_STREAM_END)
1050       {
1051          png_free(png_ptr, key);
1052          png_free(png_ptr, text);
1053          return;
1054       }
1055
1056       png_free(png_ptr, key);
1057       key = text;
1058       text += key_size;
1059
1060       text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
1061       text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt;
1062       text_ptr->key = key;
1063       text_ptr->text = text;
1064
1065       png_set_text(png_ptr, info_ptr, text_ptr, 1);
1066
1067       png_free(png_ptr, text_ptr);
1068    }
1069 }
1070 #endif
1071
1072 /* This function is called when we haven't found a handler for this
1073  * chunk.  In the future we will have code here which can handle
1074  * user-defined callback functions for unknown chunks before they are
1075  * ignored or cause an error.  If there isn't a problem with the
1076  * chunk itself (ie a bad chunk name or a critical chunk), the chunk
1077  * is (currently) silently ignored.
1078  */
1079 void
1080 png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
1081 {
1082    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
1083
1084    if (!(png_ptr->chunk_name[0] & 0x20))
1085    {
1086       png_chunk_error(png_ptr, "unknown critical chunk");
1087       /* to quiet some compiler warnings */
1088       if(info_ptr == NULL) return;
1089    }
1090
1091    png_push_crc_skip(png_ptr, length);
1092 }
1093
1094 void
1095 png_push_have_info(png_structp png_ptr, png_infop info_ptr)
1096 {
1097    if (png_ptr->info_fn != NULL)
1098       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1099 }
1100
1101 void
1102 png_push_have_end(png_structp png_ptr, png_infop info_ptr)
1103 {
1104    if (png_ptr->end_fn != NULL)
1105       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1106 }
1107
1108 void
1109 png_push_have_row(png_structp png_ptr, png_bytep row)
1110 {
1111    if (png_ptr->row_fn != NULL)
1112       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1113          (int)png_ptr->pass);
1114 }
1115
1116 void
1117 png_progressive_combine_row (png_structp png_ptr,
1118    png_bytep old_row, png_bytep new_row)
1119 {
1120    if (new_row != NULL)
1121       png_combine_row(png_ptr, old_row, png_pass_dsp_mask[png_ptr->pass]);
1122 }
1123
1124 void
1125 png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
1126    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1127    png_progressive_end_ptr end_fn)
1128 {
1129    png_ptr->info_fn = info_fn;
1130    png_ptr->row_fn = row_fn;
1131    png_ptr->end_fn = end_fn;
1132
1133    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1134 }
1135
1136 png_voidp
1137 png_get_progressive_ptr(png_structp png_ptr)
1138 {
1139    return png_ptr->io_ptr;
1140 }
1141
1142 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1143