reactos/dll/3rdparty/libpng/pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   3  *
   4  * Last changed in libpng 1.6.17 [March 26, 2015]
   5  * Copyright (c) 1998-2015 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 #include "pngpriv.h"
  15
  16 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  17
  18 /* Push model modes */
  19 #define PNG_READ_SIG_MODE   0
  20 #define PNG_READ_CHUNK_MODE 1
  21 #define PNG_READ_IDAT_MODE  2
  22 #define PNG_SKIP_MODE       3
  23 #define PNG_READ_tEXt_MODE  4
  24 #define PNG_READ_zTXt_MODE  5
  25 #define PNG_READ_DONE_MODE  6
  26 #define PNG_READ_iTXt_MODE  7
  27 #define PNG_ERROR_MODE      8
  28
  29 #define PNG_PUSH_SAVE_BUFFER_IF_FULL \
  30 if (png_ptr->push_length + 4 > png_ptr->buffer_size) \
  31    { png_push_save_buffer(png_ptr); return; }
  32 #define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \
  33 if (png_ptr->buffer_size < N) \
  34    { png_push_save_buffer(png_ptr); return; }
  35
  36 void PNGAPI
  37 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
  38     png_bytep buffer, png_size_t buffer_size)
  39 {
  40    if (png_ptr == NULL || info_ptr == NULL)
  41       return;
  42
  43    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  44
  45    while (png_ptr->buffer_size)
  46    {
  47       png_process_some_data(png_ptr, info_ptr);
  48    }
  49 }
  50
  51 png_size_t PNGAPI
  52 png_process_data_pause(png_structrp png_ptr, int save)
  53 {
  54    if (png_ptr != NULL)
  55    {
  56       /* It's easiest for the caller if we do the save; then the caller doesn't
  57        * have to supply the same data again:
  58        */
  59       if (save != 0)
  60          png_push_save_buffer(png_ptr);
  61       else
  62       {
  63          /* This includes any pending saved bytes: */
  64          png_size_t remaining = png_ptr->buffer_size;
  65          png_ptr->buffer_size = 0;
  66
  67          /* So subtract the saved buffer size, unless all the data
  68           * is actually 'saved', in which case we just return 0
  69           */
  70          if (png_ptr->save_buffer_size < remaining)
  71             return remaining - png_ptr->save_buffer_size;
  72       }
  73    }
  74
  75    return 0;
  76 }
  77
  78 png_uint_32 PNGAPI
  79 png_process_data_skip(png_structrp png_ptr)
  80 {
  81    png_uint_32 remaining = 0;
  82
  83    if (png_ptr != NULL && png_ptr->process_mode == PNG_SKIP_MODE &&
  84       png_ptr->skip_length > 0)
  85    {
  86       /* At the end of png_process_data the buffer size must be 0 (see the loop
  87        * above) so we can detect a broken call here:
  88        */
  89       if (png_ptr->buffer_size != 0)
  90          png_error(png_ptr,
  91             "png_process_data_skip called inside png_process_data");
  92
  93       /* If is impossible for there to be a saved buffer at this point -
  94        * otherwise we could not be in SKIP mode.  This will also happen if
  95        * png_process_skip is called inside png_process_data (but only very
  96        * rarely.)
  97        */
  98       if (png_ptr->save_buffer_size != 0)
  99          png_error(png_ptr, "png_process_data_skip called with saved data");
 100
 101       remaining = png_ptr->skip_length;
 102       png_ptr->skip_length = 0;
 103       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 104    }
 105
 106    return remaining;
 107 }
 108
 109 /* What we do with the incoming data depends on what we were previously
 110  * doing before we ran out of data...
 111  */
 112 void /* PRIVATE */
 113 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
 114 {
 115    if (png_ptr == NULL)
 116       return;
 117
 118    switch (png_ptr->process_mode)
 119    {
 120       case PNG_READ_SIG_MODE:
 121       {
 122          png_push_read_sig(png_ptr, info_ptr);
 123          break;
 124       }
 125
 126       case PNG_READ_CHUNK_MODE:
 127       {
 128          png_push_read_chunk(png_ptr, info_ptr);
 129          break;
 130       }
 131
 132       case PNG_READ_IDAT_MODE:
 133       {
 134          png_push_read_IDAT(png_ptr);
 135          break;
 136       }
 137
 138       case PNG_SKIP_MODE:
 139       {
 140          png_push_crc_finish(png_ptr);
 141          break;
 142       }
 143
 144       default:
 145       {
 146          png_ptr->buffer_size = 0;
 147          break;
 148       }
 149    }
 150 }
 151
 152 /* Read any remaining signature bytes from the stream and compare them with
 153  * the correct PNG signature.  It is possible that this routine is called
 154  * with bytes already read from the signature, either because they have been
 155  * checked by the calling application, or because of multiple calls to this
 156  * routine.
 157  */
 158 void /* PRIVATE */
 159 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 160 {
 161    png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
 162              num_to_check = 8 - num_checked;
 163
 164    if (png_ptr->buffer_size < num_to_check)
 165    {
 166       num_to_check = png_ptr->buffer_size;
 167    }
 168
 169    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
 170        num_to_check);
 171    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
 172
 173    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 174    {
 175       if (num_checked < 4 &&
 176           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 177          png_error(png_ptr, "Not a PNG file");
 178
 179       else
 180          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 181    }
 182    else
 183    {
 184       if (png_ptr->sig_bytes >= 8)
 185       {
 186          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 187       }
 188    }
 189 }
 190
 191 void /* PRIVATE */
 192 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
 193 {
 194    png_uint_32 chunk_name;
 195 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 196    int keep; /* unknown handling method */
 197 #endif
 198
 199    /* First we make sure we have enough data for the 4-byte chunk name
 200     * and the 4-byte chunk length before proceeding with decoding the
 201     * chunk data.  To fully decode each of these chunks, we also make
 202     * sure we have enough data in the buffer for the 4-byte CRC at the
 203     * end of every chunk (except IDAT, which is handled separately).
 204     */
 205    if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
 206    {
 207       png_byte chunk_length[4];
 208       png_byte chunk_tag[4];
 209
 210       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
 211       png_push_fill_buffer(png_ptr, chunk_length, 4);
 212       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 213       png_reset_crc(png_ptr);
 214       png_crc_read(png_ptr, chunk_tag, 4);
 215       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
 216       png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 217       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 218    }
 219
 220    chunk_name = png_ptr->chunk_name;
 221
 222    if (chunk_name == png_IDAT)
 223    {
 224       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
 225          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 226
 227       /* If we reach an IDAT chunk, this means we have read all of the
 228        * header chunks, and we can start reading the image (or if this
 229        * is called after the image has been read - we have an error).
 230        */
 231       if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
 232          png_error(png_ptr, "Missing IHDR before IDAT");
 233
 234       else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 235           (png_ptr->mode & PNG_HAVE_PLTE) == 0)
 236          png_error(png_ptr, "Missing PLTE before IDAT");
 237
 238       png_ptr->mode |= PNG_HAVE_IDAT;
 239       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 240
 241       if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
 242          if (png_ptr->push_length == 0)
 243             return;
 244
 245       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
 246          png_benign_error(png_ptr, "Too many IDATs found");
 247    }
 248
 249    if (chunk_name == png_IHDR)
 250    {
 251       if (png_ptr->push_length != 13)
 252          png_error(png_ptr, "Invalid IHDR length");
 253
 254       PNG_PUSH_SAVE_BUFFER_IF_FULL
 255       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 256    }
 257
 258    else if (chunk_name == png_IEND)
 259    {
 260       PNG_PUSH_SAVE_BUFFER_IF_FULL
 261       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 262
 263       png_ptr->process_mode = PNG_READ_DONE_MODE;
 264       png_push_have_end(png_ptr, info_ptr);
 265    }
 266
 267 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 268    else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
 269    {
 270       PNG_PUSH_SAVE_BUFFER_IF_FULL
 271       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
 272
 273       if (chunk_name == png_PLTE)
 274          png_ptr->mode |= PNG_HAVE_PLTE;
 275    }
 276 #endif
 277
 278    else if (chunk_name == png_PLTE)
 279    {
 280       PNG_PUSH_SAVE_BUFFER_IF_FULL
 281       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 282    }
 283
 284    else if (chunk_name == png_IDAT)
 285    {
 286       png_ptr->idat_size = png_ptr->push_length;
 287       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 288       png_push_have_info(png_ptr, info_ptr);
 289       png_ptr->zstream.avail_out =
 290           (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
 291           png_ptr->iwidth) + 1;
 292       png_ptr->zstream.next_out = png_ptr->row_buf;
 293       return;
 294    }
 295
 296 #ifdef PNG_READ_gAMA_SUPPORTED
 297    else if (png_ptr->chunk_name == png_gAMA)
 298    {
 299       PNG_PUSH_SAVE_BUFFER_IF_FULL
 300       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 301    }
 302
 303 #endif
 304 #ifdef PNG_READ_sBIT_SUPPORTED
 305    else if (png_ptr->chunk_name == png_sBIT)
 306    {
 307       PNG_PUSH_SAVE_BUFFER_IF_FULL
 308       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 309    }
 310
 311 #endif
 312 #ifdef PNG_READ_cHRM_SUPPORTED
 313    else if (png_ptr->chunk_name == png_cHRM)
 314    {
 315       PNG_PUSH_SAVE_BUFFER_IF_FULL
 316       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 317    }
 318
 319 #endif
 320 #ifdef PNG_READ_sRGB_SUPPORTED
 321    else if (chunk_name == png_sRGB)
 322    {
 323       PNG_PUSH_SAVE_BUFFER_IF_FULL
 324       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 325    }
 326
 327 #endif
 328 #ifdef PNG_READ_iCCP_SUPPORTED
 329    else if (png_ptr->chunk_name == png_iCCP)
 330    {
 331       PNG_PUSH_SAVE_BUFFER_IF_FULL
 332       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
 333    }
 334
 335 #endif
 336 #ifdef PNG_READ_sPLT_SUPPORTED
 337    else if (chunk_name == png_sPLT)
 338    {
 339       PNG_PUSH_SAVE_BUFFER_IF_FULL
 340       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
 341    }
 342
 343 #endif
 344 #ifdef PNG_READ_tRNS_SUPPORTED
 345    else if (chunk_name == png_tRNS)
 346    {
 347       PNG_PUSH_SAVE_BUFFER_IF_FULL
 348       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 349    }
 350
 351 #endif
 352 #ifdef PNG_READ_bKGD_SUPPORTED
 353    else if (chunk_name == png_bKGD)
 354    {
 355       PNG_PUSH_SAVE_BUFFER_IF_FULL
 356       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 357    }
 358
 359 #endif
 360 #ifdef PNG_READ_hIST_SUPPORTED
 361    else if (chunk_name == png_hIST)
 362    {
 363       PNG_PUSH_SAVE_BUFFER_IF_FULL
 364       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 365    }
 366
 367 #endif
 368 #ifdef PNG_READ_pHYs_SUPPORTED
 369    else if (chunk_name == png_pHYs)
 370    {
 371       PNG_PUSH_SAVE_BUFFER_IF_FULL
 372       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 373    }
 374
 375 #endif
 376 #ifdef PNG_READ_oFFs_SUPPORTED
 377    else if (chunk_name == png_oFFs)
 378    {
 379       PNG_PUSH_SAVE_BUFFER_IF_FULL
 380       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 381    }
 382 #endif
 383
 384 #ifdef PNG_READ_pCAL_SUPPORTED
 385    else if (chunk_name == png_pCAL)
 386    {
 387       PNG_PUSH_SAVE_BUFFER_IF_FULL
 388       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 389    }
 390
 391 #endif
 392 #ifdef PNG_READ_sCAL_SUPPORTED
 393    else if (chunk_name == png_sCAL)
 394    {
 395       PNG_PUSH_SAVE_BUFFER_IF_FULL
 396       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
 397    }
 398
 399 #endif
 400 #ifdef PNG_READ_tIME_SUPPORTED
 401    else if (chunk_name == png_tIME)
 402    {
 403       PNG_PUSH_SAVE_BUFFER_IF_FULL
 404       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 405    }
 406
 407 #endif
 408 #ifdef PNG_READ_tEXt_SUPPORTED
 409    else if (chunk_name == png_tEXt)
 410    {
 411       PNG_PUSH_SAVE_BUFFER_IF_FULL
 412       png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 413    }
 414
 415 #endif
 416 #ifdef PNG_READ_zTXt_SUPPORTED
 417    else if (chunk_name == png_zTXt)
 418    {
 419       PNG_PUSH_SAVE_BUFFER_IF_FULL
 420       png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 421    }
 422
 423 #endif
 424 #ifdef PNG_READ_iTXt_SUPPORTED
 425    else if (chunk_name == png_iTXt)
 426    {
 427       PNG_PUSH_SAVE_BUFFER_IF_FULL
 428       png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
 429    }
 430 #endif
 431
 432    else
 433    {
 434       PNG_PUSH_SAVE_BUFFER_IF_FULL
 435       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
 436          PNG_HANDLE_CHUNK_AS_DEFAULT);
 437    }
 438
 439    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 440 }
 441
 442 void /* PRIVATE */
 443 png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
 444 {
 445    png_ptr->process_mode = PNG_SKIP_MODE;
 446    png_ptr->skip_length = skip;
 447 }
 448
 449 void /* PRIVATE */
 450 png_push_crc_finish(png_structrp png_ptr)
 451 {
 452    if (png_ptr->skip_length != 0 && png_ptr->save_buffer_size != 0)
 453    {
 454       png_size_t save_size = png_ptr->save_buffer_size;
 455       png_uint_32 skip_length = png_ptr->skip_length;
 456
 457       /* We want the smaller of 'skip_length' and 'save_buffer_size', but
 458        * they are of different types and we don't know which variable has the
 459        * fewest bits.  Carefully select the smaller and cast it to the type of
 460        * the larger - this cannot overflow.  Do not cast in the following test
 461        * - it will break on either 16 or 64 bit platforms.
 462        */
 463       if (skip_length < save_size)
 464          save_size = (png_size_t)skip_length;
 465
 466       else
 467          skip_length = (png_uint_32)save_size;
 468
 469       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 470
 471       png_ptr->skip_length -= skip_length;
 472       png_ptr->buffer_size -= save_size;
 473       png_ptr->save_buffer_size -= save_size;
 474       png_ptr->save_buffer_ptr += save_size;
 475    }
 476    if (png_ptr->skip_length != 0 && png_ptr->current_buffer_size != 0)
 477    {
 478       png_size_t save_size = png_ptr->current_buffer_size;
 479       png_uint_32 skip_length = png_ptr->skip_length;
 480
 481       /* We want the smaller of 'skip_length' and 'current_buffer_size', here,
 482        * the same problem exists as above and the same solution.
 483        */
 484       if (skip_length < save_size)
 485          save_size = (png_size_t)skip_length;
 486
 487       else
 488          skip_length = (png_uint_32)save_size;
 489
 490       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 491
 492       png_ptr->skip_length -= skip_length;
 493       png_ptr->buffer_size -= save_size;
 494       png_ptr->current_buffer_size -= save_size;
 495       png_ptr->current_buffer_ptr += save_size;
 496    }
 497    if (png_ptr->skip_length == 0)
 498    {
 499       PNG_PUSH_SAVE_BUFFER_IF_LT(4)
 500       png_crc_finish(png_ptr, 0);
 501       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 502    }
 503 }
 504
 505 void PNGCBAPI
 506 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 507 {
 508    png_bytep ptr;
 509
 510    if (png_ptr == NULL)
 511       return;
 512
 513    ptr = buffer;
 514    if (png_ptr->save_buffer_size != 0)
 515    {
 516       png_size_t save_size;
 517
 518       if (length < png_ptr->save_buffer_size)
 519          save_size = length;
 520
 521       else
 522          save_size = png_ptr->save_buffer_size;
 523
 524       memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 525       length -= save_size;
 526       ptr += save_size;
 527       png_ptr->buffer_size -= save_size;
 528       png_ptr->save_buffer_size -= save_size;
 529       png_ptr->save_buffer_ptr += save_size;
 530    }
 531    if (length != 0 && png_ptr->current_buffer_size != 0)
 532    {
 533       png_size_t save_size;
 534
 535       if (length < png_ptr->current_buffer_size)
 536          save_size = length;
 537
 538       else
 539          save_size = png_ptr->current_buffer_size;
 540
 541       memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 542       png_ptr->buffer_size -= save_size;
 543       png_ptr->current_buffer_size -= save_size;
 544       png_ptr->current_buffer_ptr += save_size;
 545    }
 546 }
 547
 548 void /* PRIVATE */
 549 png_push_save_buffer(png_structrp png_ptr)
 550 {
 551    if (png_ptr->save_buffer_size != 0)
 552    {
 553       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 554       {
 555          png_size_t i, istop;
 556          png_bytep sp;
 557          png_bytep dp;
 558
 559          istop = png_ptr->save_buffer_size;
 560          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 561              i < istop; i++, sp++, dp++)
 562          {
 563             *dp = *sp;
 564          }
 565       }
 566    }
 567    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 568        png_ptr->save_buffer_max)
 569    {
 570       png_size_t new_max;
 571       png_bytep old_buffer;
 572
 573       if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
 574           (png_ptr->current_buffer_size + 256))
 575       {
 576          png_error(png_ptr, "Potential overflow of save_buffer");
 577       }
 578
 579       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 580       old_buffer = png_ptr->save_buffer;
 581       png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
 582           (png_size_t)new_max);
 583
 584       if (png_ptr->save_buffer == NULL)
 585       {
 586          png_free(png_ptr, old_buffer);
 587          old_buffer = NULL;
 588          png_error(png_ptr, "Insufficient memory for save_buffer");
 589       }
 590
 591       memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 592       png_free(png_ptr, old_buffer);
 593       old_buffer = NULL;
 594       png_ptr->save_buffer_max = new_max;
 595    }
 596    if (png_ptr->current_buffer_size)
 597    {
 598       memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 599          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 600       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 601       png_ptr->current_buffer_size = 0;
 602    }
 603    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 604    png_ptr->buffer_size = 0;
 605 }
 606
 607 void /* PRIVATE */
 608 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
 609    png_size_t buffer_length)
 610 {
 611    png_ptr->current_buffer = buffer;
 612    png_ptr->current_buffer_size = buffer_length;
 613    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 614    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 615 }
 616
 617 void /* PRIVATE */
 618 png_push_read_IDAT(png_structrp png_ptr)
 619 {
 620    if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
 621    {
 622       png_byte chunk_length[4];
 623       png_byte chunk_tag[4];
 624
 625       /* TODO: this code can be commoned up with the same code in push_read */
 626       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
 627       png_push_fill_buffer(png_ptr, chunk_length, 4);
 628       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 629       png_reset_crc(png_ptr);
 630       png_crc_read(png_ptr, chunk_tag, 4);
 631       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
 632       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 633
 634       if (png_ptr->chunk_name != png_IDAT)
 635       {
 636          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 637
 638          if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
 639             png_error(png_ptr, "Not enough compressed data");
 640
 641          return;
 642       }
 643
 644       png_ptr->idat_size = png_ptr->push_length;
 645    }
 646
 647    if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
 648    {
 649       png_size_t save_size = png_ptr->save_buffer_size;
 650       png_uint_32 idat_size = png_ptr->idat_size;
 651
 652       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
 653        * are of different types and we don't know which variable has the fewest
 654        * bits.  Carefully select the smaller and cast it to the type of the
 655        * larger - this cannot overflow.  Do not cast in the following test - it
 656        * will break on either 16 or 64 bit platforms.
 657        */
 658       if (idat_size < save_size)
 659          save_size = (png_size_t)idat_size;
 660
 661       else
 662          idat_size = (png_uint_32)save_size;
 663
 664       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 665
 666       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 667
 668       png_ptr->idat_size -= idat_size;
 669       png_ptr->buffer_size -= save_size;
 670       png_ptr->save_buffer_size -= save_size;
 671       png_ptr->save_buffer_ptr += save_size;
 672    }
 673
 674    if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
 675    {
 676       png_size_t save_size = png_ptr->current_buffer_size;
 677       png_uint_32 idat_size = png_ptr->idat_size;
 678
 679       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
 680        * are of different types and we don't know which variable has the fewest
 681        * bits.  Carefully select the smaller and cast it to the type of the
 682        * larger - this cannot overflow.
 683        */
 684       if (idat_size < save_size)
 685          save_size = (png_size_t)idat_size;
 686
 687       else
 688          idat_size = (png_uint_32)save_size;
 689
 690       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 691
 692       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 693
 694       png_ptr->idat_size -= idat_size;
 695       png_ptr->buffer_size -= save_size;
 696       png_ptr->current_buffer_size -= save_size;
 697       png_ptr->current_buffer_ptr += save_size;
 698    }
 699    if (png_ptr->idat_size == 0)
 700    {
 701       PNG_PUSH_SAVE_BUFFER_IF_LT(4)
 702       png_crc_finish(png_ptr, 0);
 703       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 704       png_ptr->mode |= PNG_AFTER_IDAT;
 705       png_ptr->zowner = 0;
 706    }
 707 }
 708
 709 void /* PRIVATE */
 710 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
 711    png_size_t buffer_length)
 712 {
 713    /* The caller checks for a non-zero buffer length. */
 714    if (!(buffer_length > 0) || buffer == NULL)
 715       png_error(png_ptr, "No IDAT data (internal error)");
 716
 717    /* This routine must process all the data it has been given
 718     * before returning, calling the row callback as required to
 719     * handle the uncompressed results.
 720     */
 721    png_ptr->zstream.next_in = buffer;
 722    /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
 723    png_ptr->zstream.avail_in = (uInt)buffer_length;
 724
 725    /* Keep going until the decompressed data is all processed
 726     * or the stream marked as finished.
 727     */
 728    while (png_ptr->zstream.avail_in > 0 &&
 729       (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
 730    {
 731       int ret;
 732
 733       /* We have data for zlib, but we must check that zlib
 734        * has someplace to put the results.  It doesn't matter
 735        * if we don't expect any results -- it may be the input
 736        * data is just the LZ end code.
 737        */
 738       if (!(png_ptr->zstream.avail_out > 0))
 739       {
 740          /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
 741          png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
 742              png_ptr->iwidth) + 1);
 743
 744          png_ptr->zstream.next_out = png_ptr->row_buf;
 745       }
 746
 747       /* Using Z_SYNC_FLUSH here means that an unterminated
 748        * LZ stream (a stream with a missing end code) can still
 749        * be handled, otherwise (Z_NO_FLUSH) a future zlib
 750        * implementation might defer output and therefore
 751        * change the current behavior (see comments in inflate.c
 752        * for why this doesn't happen at present with zlib 1.2.5).
 753        */
 754       ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
 755
 756       /* Check for any failure before proceeding. */
 757       if (ret != Z_OK && ret != Z_STREAM_END)
 758       {
 759          /* Terminate the decompression. */
 760          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 761          png_ptr->zowner = 0;
 762
 763          /* This may be a truncated stream (missing or
 764           * damaged end code).  Treat that as a warning.
 765           */
 766          if (png_ptr->row_number >= png_ptr->num_rows ||
 767              png_ptr->pass > 6)
 768             png_warning(png_ptr, "Truncated compressed data in IDAT");
 769
 770          else
 771             png_error(png_ptr, "Decompression error in IDAT");
 772
 773          /* Skip the check on unprocessed input */
 774          return;
 775       }
 776
 777       /* Did inflate output any data? */
 778       if (png_ptr->zstream.next_out != png_ptr->row_buf)
 779       {
 780          /* Is this unexpected data after the last row?
 781           * If it is, artificially terminate the LZ output
 782           * here.
 783           */
 784          if (png_ptr->row_number >= png_ptr->num_rows ||
 785              png_ptr->pass > 6)
 786          {
 787             /* Extra data. */
 788             png_warning(png_ptr, "Extra compressed data in IDAT");
 789             png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 790             png_ptr->zowner = 0;
 791
 792             /* Do no more processing; skip the unprocessed
 793              * input check below.
 794              */
 795             return;
 796          }
 797
 798          /* Do we have a complete row? */
 799          if (png_ptr->zstream.avail_out == 0)
 800             png_push_process_row(png_ptr);
 801       }
 802
 803       /* And check for the end of the stream. */
 804       if (ret == Z_STREAM_END)
 805          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 806    }
 807
 808    /* All the data should have been processed, if anything
 809     * is left at this point we have bytes of IDAT data
 810     * after the zlib end code.
 811     */
 812    if (png_ptr->zstream.avail_in > 0)
 813       png_warning(png_ptr, "Extra compression data in IDAT");
 814 }
 815
 816 void /* PRIVATE */
 817 png_push_process_row(png_structrp png_ptr)
 818 {
 819    /* 1.5.6: row_info moved out of png_struct to a local here. */
 820    png_row_info row_info;
 821
 822    row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
 823    row_info.color_type = png_ptr->color_type;
 824    row_info.bit_depth = png_ptr->bit_depth;
 825    row_info.channels = png_ptr->channels;
 826    row_info.pixel_depth = png_ptr->pixel_depth;
 827    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 828
 829    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
 830    {
 831       if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
 832          png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
 833             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
 834       else
 835          png_error(png_ptr, "bad adaptive filter value");
 836    }
 837
 838    /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
 839     * 1.5.6, while the buffer really is this big in current versions of libpng
 840     * it may not be in the future, so this was changed just to copy the
 841     * interlaced row count:
 842     */
 843    memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 844
 845 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 846    if (png_ptr->transformations != 0)
 847       png_do_read_transformations(png_ptr, &row_info);
 848 #endif
 849
 850    /* The transformed pixel depth should match the depth now in row_info. */
 851    if (png_ptr->transformed_pixel_depth == 0)
 852    {
 853       png_ptr->transformed_pixel_depth = row_info.pixel_depth;
 854       if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
 855          png_error(png_ptr, "progressive row overflow");
 856    }
 857
 858    else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
 859       png_error(png_ptr, "internal progressive row size calculation error");
 860
 861
 862 #ifdef PNG_READ_INTERLACING_SUPPORTED
 863    /* Expand interlaced rows to full size */
 864    if (png_ptr->interlaced != 0 &&
 865        (png_ptr->transformations & PNG_INTERLACE) != 0)
 866    {
 867       if (png_ptr->pass < 6)
 868          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
 869             png_ptr->transformations);
 870
 871       switch (png_ptr->pass)
 872       {
 873          case 0:
 874          {
 875             int i;
 876             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 877             {
 878                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 879                png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
 880             }
 881
 882             if (png_ptr->pass == 2) /* Pass 1 might be empty */
 883             {
 884                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 885                {
 886                   png_push_have_row(png_ptr, NULL);
 887                   png_read_push_finish_row(png_ptr);
 888                }
 889             }
 890
 891             if (png_ptr->pass == 4 && png_ptr->height <= 4)
 892             {
 893                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 894                {
 895                   png_push_have_row(png_ptr, NULL);
 896                   png_read_push_finish_row(png_ptr);
 897                }
 898             }
 899
 900             if (png_ptr->pass == 6 && png_ptr->height <= 4)
 901             {
 902                 png_push_have_row(png_ptr, NULL);
 903                 png_read_push_finish_row(png_ptr);
 904             }
 905
 906             break;
 907          }
 908
 909          case 1:
 910          {
 911             int i;
 912             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
 913             {
 914                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 915                png_read_push_finish_row(png_ptr);
 916             }
 917
 918             if (png_ptr->pass == 2) /* Skip top 4 generated rows */
 919             {
 920                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 921                {
 922                   png_push_have_row(png_ptr, NULL);
 923                   png_read_push_finish_row(png_ptr);
 924                }
 925             }
 926
 927             break;
 928          }
 929
 930          case 2:
 931          {
 932             int i;
 933
 934             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 935             {
 936                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 937                png_read_push_finish_row(png_ptr);
 938             }
 939
 940             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 941             {
 942                png_push_have_row(png_ptr, NULL);
 943                png_read_push_finish_row(png_ptr);
 944             }
 945
 946             if (png_ptr->pass == 4) /* Pass 3 might be empty */
 947             {
 948                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 949                {
 950                   png_push_have_row(png_ptr, NULL);
 951                   png_read_push_finish_row(png_ptr);
 952                }
 953             }
 954
 955             break;
 956          }
 957
 958          case 3:
 959          {
 960             int i;
 961
 962             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
 963             {
 964                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 965                png_read_push_finish_row(png_ptr);
 966             }
 967
 968             if (png_ptr->pass == 4) /* Skip top two generated rows */
 969             {
 970                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 971                {
 972                   png_push_have_row(png_ptr, NULL);
 973                   png_read_push_finish_row(png_ptr);
 974                }
 975             }
 976
 977             break;
 978          }
 979
 980          case 4:
 981          {
 982             int i;
 983
 984             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 985             {
 986                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 987                png_read_push_finish_row(png_ptr);
 988             }
 989
 990             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 991             {
 992                png_push_have_row(png_ptr, NULL);
 993                png_read_push_finish_row(png_ptr);
 994             }
 995
 996             if (png_ptr->pass == 6) /* Pass 5 might be empty */
 997             {
 998                png_push_have_row(png_ptr, NULL);
 999                png_read_push_finish_row(png_ptr);
1000             }
1001
1002             break;
1003          }
1004
1005          case 5:
1006          {
1007             int i;
1008
1009             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
1010             {
1011                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1012                png_read_push_finish_row(png_ptr);
1013             }
1014
1015             if (png_ptr->pass == 6) /* Skip top generated row */
1016             {
1017                png_push_have_row(png_ptr, NULL);
1018                png_read_push_finish_row(png_ptr);
1019             }
1020
1021             break;
1022          }
1023
1024          default:
1025          case 6:
1026          {
1027             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1028             png_read_push_finish_row(png_ptr);
1029
1030             if (png_ptr->pass != 6)
1031                break;
1032
1033             png_push_have_row(png_ptr, NULL);
1034             png_read_push_finish_row(png_ptr);
1035          }
1036       }
1037    }
1038    else
1039 #endif
1040    {
1041       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1042       png_read_push_finish_row(png_ptr);
1043    }
1044 }
1045
1046 void /* PRIVATE */
1047 png_read_push_finish_row(png_structrp png_ptr)
1048 {
1049 #ifdef PNG_READ_INTERLACING_SUPPORTED
1050    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1051
1052    /* Start of interlace block */
1053    static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
1054
1055    /* Offset to next interlace block */
1056    static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
1057
1058    /* Start of interlace block in the y direction */
1059    static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
1060
1061    /* Offset to next interlace block in the y direction */
1062    static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
1063
1064    /* Height of interlace block.  This is not currently used - if you need
1065     * it, uncomment it here and in png.h
1066    static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
1067    */
1068 #endif
1069
1070    png_ptr->row_number++;
1071    if (png_ptr->row_number < png_ptr->num_rows)
1072       return;
1073
1074 #ifdef PNG_READ_INTERLACING_SUPPORTED
1075    if (png_ptr->interlaced != 0)
1076    {
1077       png_ptr->row_number = 0;
1078       memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
1079
1080       do
1081       {
1082          png_ptr->pass++;
1083          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1084              (png_ptr->pass == 3 && png_ptr->width < 3) ||
1085              (png_ptr->pass == 5 && png_ptr->width < 2))
1086             png_ptr->pass++;
1087
1088          if (png_ptr->pass > 7)
1089             png_ptr->pass--;
1090
1091          if (png_ptr->pass >= 7)
1092             break;
1093
1094          png_ptr->iwidth = (png_ptr->width +
1095              png_pass_inc[png_ptr->pass] - 1 -
1096              png_pass_start[png_ptr->pass]) /
1097              png_pass_inc[png_ptr->pass];
1098
1099          if ((png_ptr->transformations & PNG_INTERLACE) != 0)
1100             break;
1101
1102          png_ptr->num_rows = (png_ptr->height +
1103              png_pass_yinc[png_ptr->pass] - 1 -
1104              png_pass_ystart[png_ptr->pass]) /
1105              png_pass_yinc[png_ptr->pass];
1106
1107       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1108    }
1109 #endif /* READ_INTERLACING */
1110 }
1111
1112 void /* PRIVATE */
1113 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1114 {
1115    if (png_ptr->info_fn != NULL)
1116       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1117 }
1118
1119 void /* PRIVATE */
1120 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1121 {
1122    if (png_ptr->end_fn != NULL)
1123       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1124 }
1125
1126 void /* PRIVATE */
1127 png_push_have_row(png_structrp png_ptr, png_bytep row)
1128 {
1129    if (png_ptr->row_fn != NULL)
1130       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1131          (int)png_ptr->pass);
1132 }
1133
1134 #ifdef PNG_READ_INTERLACING_SUPPORTED
1135 void PNGAPI
1136 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1137     png_const_bytep new_row)
1138 {
1139    if (png_ptr == NULL)
1140       return;
1141
1142    /* new_row is a flag here - if it is NULL then the app callback was called
1143     * from an empty row (see the calls to png_struct::row_fn below), otherwise
1144     * it must be png_ptr->row_buf+1
1145     */
1146    if (new_row != NULL)
1147       png_combine_row(png_ptr, old_row, 1/*blocky display*/);
1148 }
1149 #endif /* READ_INTERLACING */
1150
1151 void PNGAPI
1152 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1153     png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1154     png_progressive_end_ptr end_fn)
1155 {
1156    if (png_ptr == NULL)
1157       return;
1158
1159    png_ptr->info_fn = info_fn;
1160    png_ptr->row_fn = row_fn;
1161    png_ptr->end_fn = end_fn;
1162
1163    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1164 }
1165
1166 png_voidp PNGAPI
1167 png_get_progressive_ptr(png_const_structrp png_ptr)
1168 {
1169    if (png_ptr == NULL)
1170       return (NULL);
1171
1172    return png_ptr->io_ptr;
1173 }
1174 #endif /* PROGRESSIVE_READ */