dll/3rdparty/libpng/pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   3  *
   4  * Copyright (c) 2018 Cosmin Truta
   5  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
   6  * Copyright (c) 1996-1997 Andreas Dilger
   7  * 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_READ_tEXt_MODE  4
  23 #define PNG_READ_zTXt_MODE  5
  24 #define PNG_READ_DONE_MODE  6
  25 #define PNG_READ_iTXt_MODE  7
  26 #define PNG_ERROR_MODE      8
  27
  28 #define PNG_PUSH_SAVE_BUFFER_IF_FULL \
  29 if (png_ptr->push_length + 4 > png_ptr->buffer_size) \
  30    { png_push_save_buffer(png_ptr); return; }
  31 #define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \
  32 if (png_ptr->buffer_size < N) \
  33    { png_push_save_buffer(png_ptr); return; }
  34
  35 void PNGAPI
  36 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
  37     png_bytep buffer, size_t buffer_size)
  38 {
  39    if (png_ptr == NULL || info_ptr == NULL)
  40       return;
  41
  42    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  43
  44    while (png_ptr->buffer_size)
  45    {
  46       png_process_some_data(png_ptr, info_ptr);
  47    }
  48 }
  49
  50 size_t PNGAPI
  51 png_process_data_pause(png_structrp png_ptr, int save)
  52 {
  53    if (png_ptr != NULL)
  54    {
  55       /* It's easiest for the caller if we do the save; then the caller doesn't
  56        * have to supply the same data again:
  57        */
  58       if (save != 0)
  59          png_push_save_buffer(png_ptr);
  60       else
  61       {
  62          /* This includes any pending saved bytes: */
  63          size_t remaining = png_ptr->buffer_size;
  64          png_ptr->buffer_size = 0;
  65
  66          /* So subtract the saved buffer size, unless all the data
  67           * is actually 'saved', in which case we just return 0
  68           */
  69          if (png_ptr->save_buffer_size < remaining)
  70             return remaining - png_ptr->save_buffer_size;
  71       }
  72    }
  73
  74    return 0;
  75 }
  76
  77 png_uint_32 PNGAPI
  78 png_process_data_skip(png_structrp png_ptr)
  79 {
  80 /* TODO: Deprecate and remove this API.
  81  * Somewhere the implementation of this seems to have been lost,
  82  * or abandoned.  It was only to support some internal back-door access
  83  * to png_struct) in libpng-1.4.x.
  84  */
  85    png_app_warning(png_ptr,
  86 "png_process_data_skip is not implemented in any current version of libpng");
  87    return 0;
  88 }
  89
  90 /* What we do with the incoming data depends on what we were previously
  91  * doing before we ran out of data...
  92  */
  93 void /* PRIVATE */
  94 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
  95 {
  96    if (png_ptr == NULL)
  97       return;
  98
  99    switch (png_ptr->process_mode)
 100    {
 101       case PNG_READ_SIG_MODE:
 102       {
 103          png_push_read_sig(png_ptr, info_ptr);
 104          break;
 105       }
 106
 107       case PNG_READ_CHUNK_MODE:
 108       {
 109          png_push_read_chunk(png_ptr, info_ptr);
 110          break;
 111       }
 112
 113       case PNG_READ_IDAT_MODE:
 114       {
 115          png_push_read_IDAT(png_ptr);
 116          break;
 117       }
 118
 119       default:
 120       {
 121          png_ptr->buffer_size = 0;
 122          break;
 123       }
 124    }
 125 }
 126
 127 /* Read any remaining signature bytes from the stream and compare them with
 128  * the correct PNG signature.  It is possible that this routine is called
 129  * with bytes already read from the signature, either because they have been
 130  * checked by the calling application, or because of multiple calls to this
 131  * routine.
 132  */
 133 void /* PRIVATE */
 134 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 135 {
 136    size_t num_checked = png_ptr->sig_bytes; /* SAFE, does not exceed 8 */
 137    size_t num_to_check = 8 - num_checked;
 138
 139    if (png_ptr->buffer_size < num_to_check)
 140    {
 141       num_to_check = png_ptr->buffer_size;
 142    }
 143
 144    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
 145        num_to_check);
 146    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
 147
 148    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 149    {
 150       if (num_checked < 4 &&
 151           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 152          png_error(png_ptr, "Not a PNG file");
 153
 154       else
 155          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 156    }
 157    else
 158    {
 159       if (png_ptr->sig_bytes >= 8)
 160       {
 161          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 162       }
 163    }
 164 }
 165
 166 void /* PRIVATE */
 167 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
 168 {
 169    png_uint_32 chunk_name;
 170 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 171    int keep; /* unknown handling method */
 172 #endif
 173
 174    /* First we make sure we have enough data for the 4-byte chunk name
 175     * and the 4-byte chunk length before proceeding with decoding the
 176     * chunk data.  To fully decode each of these chunks, we also make
 177     * sure we have enough data in the buffer for the 4-byte CRC at the
 178     * end of every chunk (except IDAT, which is handled separately).
 179     */
 180    if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
 181    {
 182       png_byte chunk_length[4];
 183       png_byte chunk_tag[4];
 184
 185       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
 186       png_push_fill_buffer(png_ptr, chunk_length, 4);
 187       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 188       png_reset_crc(png_ptr);
 189       png_crc_read(png_ptr, chunk_tag, 4);
 190       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
 191       png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 192       png_check_chunk_length(png_ptr, png_ptr->push_length);
 193       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 194    }
 195
 196    chunk_name = png_ptr->chunk_name;
 197
 198    if (chunk_name == png_IDAT)
 199    {
 200       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
 201          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 202
 203       /* If we reach an IDAT chunk, this means we have read all of the
 204        * header chunks, and we can start reading the image (or if this
 205        * is called after the image has been read - we have an error).
 206        */
 207       if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
 208          png_error(png_ptr, "Missing IHDR before IDAT");
 209
 210       else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 211           (png_ptr->mode & PNG_HAVE_PLTE) == 0)
 212          png_error(png_ptr, "Missing PLTE before IDAT");
 213
 214       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 215
 216       if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
 217          if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
 218             if (png_ptr->push_length == 0)
 219                return;
 220
 221       png_ptr->mode |= PNG_HAVE_IDAT;
 222
 223       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
 224          png_benign_error(png_ptr, "Too many IDATs found");
 225    }
 226
 227    if (chunk_name == png_IHDR)
 228    {
 229       if (png_ptr->push_length != 13)
 230          png_error(png_ptr, "Invalid IHDR length");
 231
 232       PNG_PUSH_SAVE_BUFFER_IF_FULL
 233       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 234    }
 235
 236    else if (chunk_name == png_IEND)
 237    {
 238       PNG_PUSH_SAVE_BUFFER_IF_FULL
 239       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 240
 241       png_ptr->process_mode = PNG_READ_DONE_MODE;
 242       png_push_have_end(png_ptr, info_ptr);
 243    }
 244
 245 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 246    else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
 247    {
 248       PNG_PUSH_SAVE_BUFFER_IF_FULL
 249       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
 250
 251       if (chunk_name == png_PLTE)
 252          png_ptr->mode |= PNG_HAVE_PLTE;
 253    }
 254 #endif
 255
 256    else if (chunk_name == png_PLTE)
 257    {
 258       PNG_PUSH_SAVE_BUFFER_IF_FULL
 259       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 260    }
 261
 262    else if (chunk_name == png_IDAT)
 263    {
 264       png_ptr->idat_size = png_ptr->push_length;
 265       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 266       png_push_have_info(png_ptr, info_ptr);
 267       png_ptr->zstream.avail_out =
 268           (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
 269           png_ptr->iwidth) + 1;
 270       png_ptr->zstream.next_out = png_ptr->row_buf;
 271       return;
 272    }
 273
 274 #ifdef PNG_READ_gAMA_SUPPORTED
 275    else if (png_ptr->chunk_name == png_gAMA)
 276    {
 277       PNG_PUSH_SAVE_BUFFER_IF_FULL
 278       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 279    }
 280
 281 #endif
 282 #ifdef PNG_READ_sBIT_SUPPORTED
 283    else if (png_ptr->chunk_name == png_sBIT)
 284    {
 285       PNG_PUSH_SAVE_BUFFER_IF_FULL
 286       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 287    }
 288
 289 #endif
 290 #ifdef PNG_READ_cHRM_SUPPORTED
 291    else if (png_ptr->chunk_name == png_cHRM)
 292    {
 293       PNG_PUSH_SAVE_BUFFER_IF_FULL
 294       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 295    }
 296
 297 #endif
 298 #ifdef PNG_READ_sRGB_SUPPORTED
 299    else if (chunk_name == png_sRGB)
 300    {
 301       PNG_PUSH_SAVE_BUFFER_IF_FULL
 302       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 303    }
 304
 305 #endif
 306 #ifdef PNG_READ_iCCP_SUPPORTED
 307    else if (png_ptr->chunk_name == png_iCCP)
 308    {
 309       PNG_PUSH_SAVE_BUFFER_IF_FULL
 310       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
 311    }
 312
 313 #endif
 314 #ifdef PNG_READ_sPLT_SUPPORTED
 315    else if (chunk_name == png_sPLT)
 316    {
 317       PNG_PUSH_SAVE_BUFFER_IF_FULL
 318       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
 319    }
 320
 321 #endif
 322 #ifdef PNG_READ_tRNS_SUPPORTED
 323    else if (chunk_name == png_tRNS)
 324    {
 325       PNG_PUSH_SAVE_BUFFER_IF_FULL
 326       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 327    }
 328
 329 #endif
 330 #ifdef PNG_READ_bKGD_SUPPORTED
 331    else if (chunk_name == png_bKGD)
 332    {
 333       PNG_PUSH_SAVE_BUFFER_IF_FULL
 334       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 335    }
 336
 337 #endif
 338 #ifdef PNG_READ_hIST_SUPPORTED
 339    else if (chunk_name == png_hIST)
 340    {
 341       PNG_PUSH_SAVE_BUFFER_IF_FULL
 342       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 343    }
 344
 345 #endif
 346 #ifdef PNG_READ_pHYs_SUPPORTED
 347    else if (chunk_name == png_pHYs)
 348    {
 349       PNG_PUSH_SAVE_BUFFER_IF_FULL
 350       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 351    }
 352
 353 #endif
 354 #ifdef PNG_READ_oFFs_SUPPORTED
 355    else if (chunk_name == png_oFFs)
 356    {
 357       PNG_PUSH_SAVE_BUFFER_IF_FULL
 358       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 359    }
 360 #endif
 361
 362 #ifdef PNG_READ_pCAL_SUPPORTED
 363    else if (chunk_name == png_pCAL)
 364    {
 365       PNG_PUSH_SAVE_BUFFER_IF_FULL
 366       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 367    }
 368
 369 #endif
 370 #ifdef PNG_READ_sCAL_SUPPORTED
 371    else if (chunk_name == png_sCAL)
 372    {
 373       PNG_PUSH_SAVE_BUFFER_IF_FULL
 374       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
 375    }
 376
 377 #endif
 378 #ifdef PNG_READ_tIME_SUPPORTED
 379    else if (chunk_name == png_tIME)
 380    {
 381       PNG_PUSH_SAVE_BUFFER_IF_FULL
 382       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 383    }
 384
 385 #endif
 386 #ifdef PNG_READ_tEXt_SUPPORTED
 387    else if (chunk_name == png_tEXt)
 388    {
 389       PNG_PUSH_SAVE_BUFFER_IF_FULL
 390       png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 391    }
 392
 393 #endif
 394 #ifdef PNG_READ_zTXt_SUPPORTED
 395    else if (chunk_name == png_zTXt)
 396    {
 397       PNG_PUSH_SAVE_BUFFER_IF_FULL
 398       png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 399    }
 400
 401 #endif
 402 #ifdef PNG_READ_iTXt_SUPPORTED
 403    else if (chunk_name == png_iTXt)
 404    {
 405       PNG_PUSH_SAVE_BUFFER_IF_FULL
 406       png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
 407    }
 408 #endif
 409
 410    else
 411    {
 412       PNG_PUSH_SAVE_BUFFER_IF_FULL
 413       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
 414           PNG_HANDLE_CHUNK_AS_DEFAULT);
 415    }
 416
 417    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 418 }
 419
 420 void PNGCBAPI
 421 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, size_t length)
 422 {
 423    png_bytep ptr;
 424
 425    if (png_ptr == NULL)
 426       return;
 427
 428    ptr = buffer;
 429    if (png_ptr->save_buffer_size != 0)
 430    {
 431       size_t save_size;
 432
 433       if (length < png_ptr->save_buffer_size)
 434          save_size = length;
 435
 436       else
 437          save_size = png_ptr->save_buffer_size;
 438
 439       memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 440       length -= save_size;
 441       ptr += save_size;
 442       png_ptr->buffer_size -= save_size;
 443       png_ptr->save_buffer_size -= save_size;
 444       png_ptr->save_buffer_ptr += save_size;
 445    }
 446    if (length != 0 && png_ptr->current_buffer_size != 0)
 447    {
 448       size_t save_size;
 449
 450       if (length < png_ptr->current_buffer_size)
 451          save_size = length;
 452
 453       else
 454          save_size = png_ptr->current_buffer_size;
 455
 456       memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 457       png_ptr->buffer_size -= save_size;
 458       png_ptr->current_buffer_size -= save_size;
 459       png_ptr->current_buffer_ptr += save_size;
 460    }
 461 }
 462
 463 void /* PRIVATE */
 464 png_push_save_buffer(png_structrp png_ptr)
 465 {
 466    if (png_ptr->save_buffer_size != 0)
 467    {
 468       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 469       {
 470          size_t i, istop;
 471          png_bytep sp;
 472          png_bytep dp;
 473
 474          istop = png_ptr->save_buffer_size;
 475          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 476              i < istop; i++, sp++, dp++)
 477          {
 478             *dp = *sp;
 479          }
 480       }
 481    }
 482    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 483        png_ptr->save_buffer_max)
 484    {
 485       size_t new_max;
 486       png_bytep old_buffer;
 487
 488       if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
 489           (png_ptr->current_buffer_size + 256))
 490       {
 491          png_error(png_ptr, "Potential overflow of save_buffer");
 492       }
 493
 494       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 495       old_buffer = png_ptr->save_buffer;
 496       png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
 497           (size_t)new_max);
 498
 499       if (png_ptr->save_buffer == NULL)
 500       {
 501          png_free(png_ptr, old_buffer);
 502          png_error(png_ptr, "Insufficient memory for save_buffer");
 503       }
 504
 505       if (old_buffer)
 506          memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 507       else if (png_ptr->save_buffer_size)
 508          png_error(png_ptr, "save_buffer error");
 509       png_free(png_ptr, old_buffer);
 510       png_ptr->save_buffer_max = new_max;
 511    }
 512    if (png_ptr->current_buffer_size)
 513    {
 514       memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 515          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 516       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 517       png_ptr->current_buffer_size = 0;
 518    }
 519    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 520    png_ptr->buffer_size = 0;
 521 }
 522
 523 void /* PRIVATE */
 524 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
 525     size_t buffer_length)
 526 {
 527    png_ptr->current_buffer = buffer;
 528    png_ptr->current_buffer_size = buffer_length;
 529    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 530    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 531 }
 532
 533 void /* PRIVATE */
 534 png_push_read_IDAT(png_structrp png_ptr)
 535 {
 536    if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
 537    {
 538       png_byte chunk_length[4];
 539       png_byte chunk_tag[4];
 540
 541       /* TODO: this code can be commoned up with the same code in push_read */
 542       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
 543       png_push_fill_buffer(png_ptr, chunk_length, 4);
 544       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 545       png_reset_crc(png_ptr);
 546       png_crc_read(png_ptr, chunk_tag, 4);
 547       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
 548       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 549
 550       if (png_ptr->chunk_name != png_IDAT)
 551       {
 552          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 553
 554          if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
 555             png_error(png_ptr, "Not enough compressed data");
 556
 557          return;
 558       }
 559
 560       png_ptr->idat_size = png_ptr->push_length;
 561    }
 562
 563    if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
 564    {
 565       size_t save_size = png_ptr->save_buffer_size;
 566       png_uint_32 idat_size = png_ptr->idat_size;
 567
 568       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
 569        * are of different types and we don't know which variable has the fewest
 570        * bits.  Carefully select the smaller and cast it to the type of the
 571        * larger - this cannot overflow.  Do not cast in the following test - it
 572        * will break on either 16-bit or 64-bit platforms.
 573        */
 574       if (idat_size < save_size)
 575          save_size = (size_t)idat_size;
 576
 577       else
 578          idat_size = (png_uint_32)save_size;
 579
 580       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 581
 582       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 583
 584       png_ptr->idat_size -= idat_size;
 585       png_ptr->buffer_size -= save_size;
 586       png_ptr->save_buffer_size -= save_size;
 587       png_ptr->save_buffer_ptr += save_size;
 588    }
 589
 590    if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
 591    {
 592       size_t save_size = png_ptr->current_buffer_size;
 593       png_uint_32 idat_size = png_ptr->idat_size;
 594
 595       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
 596        * are of different types and we don't know which variable has the fewest
 597        * bits.  Carefully select the smaller and cast it to the type of the
 598        * larger - this cannot overflow.
 599        */
 600       if (idat_size < save_size)
 601          save_size = (size_t)idat_size;
 602
 603       else
 604          idat_size = (png_uint_32)save_size;
 605
 606       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 607
 608       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 609
 610       png_ptr->idat_size -= idat_size;
 611       png_ptr->buffer_size -= save_size;
 612       png_ptr->current_buffer_size -= save_size;
 613       png_ptr->current_buffer_ptr += save_size;
 614    }
 615
 616    if (png_ptr->idat_size == 0)
 617    {
 618       PNG_PUSH_SAVE_BUFFER_IF_LT(4)
 619       png_crc_finish(png_ptr, 0);
 620       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 621       png_ptr->mode |= PNG_AFTER_IDAT;
 622       png_ptr->zowner = 0;
 623    }
 624 }
 625
 626 void /* PRIVATE */
 627 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
 628     size_t buffer_length)
 629 {
 630    /* The caller checks for a non-zero buffer length. */
 631    if (!(buffer_length > 0) || buffer == NULL)
 632       png_error(png_ptr, "No IDAT data (internal error)");
 633
 634    /* This routine must process all the data it has been given
 635     * before returning, calling the row callback as required to
 636     * handle the uncompressed results.
 637     */
 638    png_ptr->zstream.next_in = buffer;
 639    /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
 640    png_ptr->zstream.avail_in = (uInt)buffer_length;
 641
 642    /* Keep going until the decompressed data is all processed
 643     * or the stream marked as finished.
 644     */
 645    while (png_ptr->zstream.avail_in > 0 &&
 646       (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
 647    {
 648       int ret;
 649
 650       /* We have data for zlib, but we must check that zlib
 651        * has someplace to put the results.  It doesn't matter
 652        * if we don't expect any results -- it may be the input
 653        * data is just the LZ end code.
 654        */
 655       if (!(png_ptr->zstream.avail_out > 0))
 656       {
 657          /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
 658          png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
 659              png_ptr->iwidth) + 1);
 660
 661          png_ptr->zstream.next_out = png_ptr->row_buf;
 662       }
 663
 664       /* Using Z_SYNC_FLUSH here means that an unterminated
 665        * LZ stream (a stream with a missing end code) can still
 666        * be handled, otherwise (Z_NO_FLUSH) a future zlib
 667        * implementation might defer output and therefore
 668        * change the current behavior (see comments in inflate.c
 669        * for why this doesn't happen at present with zlib 1.2.5).
 670        */
 671       ret = PNG_INFLATE(png_ptr, Z_SYNC_FLUSH);
 672
 673       /* Check for any failure before proceeding. */
 674       if (ret != Z_OK && ret != Z_STREAM_END)
 675       {
 676          /* Terminate the decompression. */
 677          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 678          png_ptr->zowner = 0;
 679
 680          /* This may be a truncated stream (missing or
 681           * damaged end code).  Treat that as a warning.
 682           */
 683          if (png_ptr->row_number >= png_ptr->num_rows ||
 684              png_ptr->pass > 6)
 685             png_warning(png_ptr, "Truncated compressed data in IDAT");
 686
 687          else
 688          {
 689             if (ret == Z_DATA_ERROR)
 690                png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
 691             else
 692                png_error(png_ptr, "Decompression error in IDAT");
 693          }
 694
 695          /* Skip the check on unprocessed input */
 696          return;
 697       }
 698
 699       /* Did inflate output any data? */
 700       if (png_ptr->zstream.next_out != png_ptr->row_buf)
 701       {
 702          /* Is this unexpected data after the last row?
 703           * If it is, artificially terminate the LZ output
 704           * here.
 705           */
 706          if (png_ptr->row_number >= png_ptr->num_rows ||
 707              png_ptr->pass > 6)
 708          {
 709             /* Extra data. */
 710             png_warning(png_ptr, "Extra compressed data in IDAT");
 711             png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 712             png_ptr->zowner = 0;
 713
 714             /* Do no more processing; skip the unprocessed
 715              * input check below.
 716              */
 717             return;
 718          }
 719
 720          /* Do we have a complete row? */
 721          if (png_ptr->zstream.avail_out == 0)
 722             png_push_process_row(png_ptr);
 723       }
 724
 725       /* And check for the end of the stream. */
 726       if (ret == Z_STREAM_END)
 727          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
 728    }
 729
 730    /* All the data should have been processed, if anything
 731     * is left at this point we have bytes of IDAT data
 732     * after the zlib end code.
 733     */
 734    if (png_ptr->zstream.avail_in > 0)
 735       png_warning(png_ptr, "Extra compression data in IDAT");
 736 }
 737
 738 void /* PRIVATE */
 739 png_push_process_row(png_structrp png_ptr)
 740 {
 741    /* 1.5.6: row_info moved out of png_struct to a local here. */
 742    png_row_info row_info;
 743
 744    row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
 745    row_info.color_type = png_ptr->color_type;
 746    row_info.bit_depth = png_ptr->bit_depth;
 747    row_info.channels = png_ptr->channels;
 748    row_info.pixel_depth = png_ptr->pixel_depth;
 749    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 750
 751    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
 752    {
 753       if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
 754          png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
 755             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
 756       else
 757          png_error(png_ptr, "bad adaptive filter value");
 758    }
 759
 760    /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
 761     * 1.5.6, while the buffer really is this big in current versions of libpng
 762     * it may not be in the future, so this was changed just to copy the
 763     * interlaced row count:
 764     */
 765    memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 766
 767 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 768    if (png_ptr->transformations != 0)
 769       png_do_read_transformations(png_ptr, &row_info);
 770 #endif
 771
 772    /* The transformed pixel depth should match the depth now in row_info. */
 773    if (png_ptr->transformed_pixel_depth == 0)
 774    {
 775       png_ptr->transformed_pixel_depth = row_info.pixel_depth;
 776       if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
 777          png_error(png_ptr, "progressive row overflow");
 778    }
 779
 780    else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
 781       png_error(png_ptr, "internal progressive row size calculation error");
 782
 783
 784 #ifdef PNG_READ_INTERLACING_SUPPORTED
 785    /* Expand interlaced rows to full size */
 786    if (png_ptr->interlaced != 0 &&
 787        (png_ptr->transformations & PNG_INTERLACE) != 0)
 788    {
 789       if (png_ptr->pass < 6)
 790          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
 791              png_ptr->transformations);
 792
 793       switch (png_ptr->pass)
 794       {
 795          case 0:
 796          {
 797             int i;
 798             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 799             {
 800                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 801                png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
 802             }
 803
 804             if (png_ptr->pass == 2) /* Pass 1 might be empty */
 805             {
 806                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 807                {
 808                   png_push_have_row(png_ptr, NULL);
 809                   png_read_push_finish_row(png_ptr);
 810                }
 811             }
 812
 813             if (png_ptr->pass == 4 && png_ptr->height <= 4)
 814             {
 815                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 816                {
 817                   png_push_have_row(png_ptr, NULL);
 818                   png_read_push_finish_row(png_ptr);
 819                }
 820             }
 821
 822             if (png_ptr->pass == 6 && png_ptr->height <= 4)
 823             {
 824                 png_push_have_row(png_ptr, NULL);
 825                 png_read_push_finish_row(png_ptr);
 826             }
 827
 828             break;
 829          }
 830
 831          case 1:
 832          {
 833             int i;
 834             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
 835             {
 836                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 837                png_read_push_finish_row(png_ptr);
 838             }
 839
 840             if (png_ptr->pass == 2) /* Skip top 4 generated rows */
 841             {
 842                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 843                {
 844                   png_push_have_row(png_ptr, NULL);
 845                   png_read_push_finish_row(png_ptr);
 846                }
 847             }
 848
 849             break;
 850          }
 851
 852          case 2:
 853          {
 854             int i;
 855
 856             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 857             {
 858                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 859                png_read_push_finish_row(png_ptr);
 860             }
 861
 862             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 863             {
 864                png_push_have_row(png_ptr, NULL);
 865                png_read_push_finish_row(png_ptr);
 866             }
 867
 868             if (png_ptr->pass == 4) /* Pass 3 might be empty */
 869             {
 870                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 871                {
 872                   png_push_have_row(png_ptr, NULL);
 873                   png_read_push_finish_row(png_ptr);
 874                }
 875             }
 876
 877             break;
 878          }
 879
 880          case 3:
 881          {
 882             int i;
 883
 884             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
 885             {
 886                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 887                png_read_push_finish_row(png_ptr);
 888             }
 889
 890             if (png_ptr->pass == 4) /* Skip top two generated rows */
 891             {
 892                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 893                {
 894                   png_push_have_row(png_ptr, NULL);
 895                   png_read_push_finish_row(png_ptr);
 896                }
 897             }
 898
 899             break;
 900          }
 901
 902          case 4:
 903          {
 904             int i;
 905
 906             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 907             {
 908                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 909                png_read_push_finish_row(png_ptr);
 910             }
 911
 912             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 913             {
 914                png_push_have_row(png_ptr, NULL);
 915                png_read_push_finish_row(png_ptr);
 916             }
 917
 918             if (png_ptr->pass == 6) /* Pass 5 might be empty */
 919             {
 920                png_push_have_row(png_ptr, NULL);
 921                png_read_push_finish_row(png_ptr);
 922             }
 923
 924             break;
 925          }
 926
 927          case 5:
 928          {
 929             int i;
 930
 931             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
 932             {
 933                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 934                png_read_push_finish_row(png_ptr);
 935             }
 936
 937             if (png_ptr->pass == 6) /* Skip top generated row */
 938             {
 939                png_push_have_row(png_ptr, NULL);
 940                png_read_push_finish_row(png_ptr);
 941             }
 942
 943             break;
 944          }
 945
 946          default:
 947          case 6:
 948          {
 949             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 950             png_read_push_finish_row(png_ptr);
 951
 952             if (png_ptr->pass != 6)
 953                break;
 954
 955             png_push_have_row(png_ptr, NULL);
 956             png_read_push_finish_row(png_ptr);
 957          }
 958       }
 959    }
 960    else
 961 #endif
 962    {
 963       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 964       png_read_push_finish_row(png_ptr);
 965    }
 966 }
 967
 968 void /* PRIVATE */
 969 png_read_push_finish_row(png_structrp png_ptr)
 970 {
 971 #ifdef PNG_READ_INTERLACING_SUPPORTED
 972    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 973
 974    /* Start of interlace block */
 975    static const png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 976
 977    /* Offset to next interlace block */
 978    static const png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 979
 980    /* Start of interlace block in the y direction */
 981    static const png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 982
 983    /* Offset to next interlace block in the y direction */
 984    static const png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 985
 986    /* Height of interlace block.  This is not currently used - if you need
 987     * it, uncomment it here and in png.h
 988    static const png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
 989    */
 990 #endif
 991
 992    png_ptr->row_number++;
 993    if (png_ptr->row_number < png_ptr->num_rows)
 994       return;
 995
 996 #ifdef PNG_READ_INTERLACING_SUPPORTED
 997    if (png_ptr->interlaced != 0)
 998    {
 999       png_ptr->row_number = 0;
1000       memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
1001
1002       do
1003       {
1004          png_ptr->pass++;
1005          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1006              (png_ptr->pass == 3 && png_ptr->width < 3) ||
1007              (png_ptr->pass == 5 && png_ptr->width < 2))
1008             png_ptr->pass++;
1009
1010          if (png_ptr->pass > 7)
1011             png_ptr->pass--;
1012
1013          if (png_ptr->pass >= 7)
1014             break;
1015
1016          png_ptr->iwidth = (png_ptr->width +
1017              png_pass_inc[png_ptr->pass] - 1 -
1018              png_pass_start[png_ptr->pass]) /
1019              png_pass_inc[png_ptr->pass];
1020
1021          if ((png_ptr->transformations & PNG_INTERLACE) != 0)
1022             break;
1023
1024          png_ptr->num_rows = (png_ptr->height +
1025              png_pass_yinc[png_ptr->pass] - 1 -
1026              png_pass_ystart[png_ptr->pass]) /
1027              png_pass_yinc[png_ptr->pass];
1028
1029       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1030    }
1031 #endif /* READ_INTERLACING */
1032 }
1033
1034 void /* PRIVATE */
1035 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1036 {
1037    if (png_ptr->info_fn != NULL)
1038       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1039 }
1040
1041 void /* PRIVATE */
1042 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1043 {
1044    if (png_ptr->end_fn != NULL)
1045       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1046 }
1047
1048 void /* PRIVATE */
1049 png_push_have_row(png_structrp png_ptr, png_bytep row)
1050 {
1051    if (png_ptr->row_fn != NULL)
1052       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1053           (int)png_ptr->pass);
1054 }
1055
1056 #ifdef PNG_READ_INTERLACING_SUPPORTED
1057 void PNGAPI
1058 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1059     png_const_bytep new_row)
1060 {
1061    if (png_ptr == NULL)
1062       return;
1063
1064    /* new_row is a flag here - if it is NULL then the app callback was called
1065     * from an empty row (see the calls to png_struct::row_fn below), otherwise
1066     * it must be png_ptr->row_buf+1
1067     */
1068    if (new_row != NULL)
1069       png_combine_row(png_ptr, old_row, 1/*blocky display*/);
1070 }
1071 #endif /* READ_INTERLACING */
1072
1073 void PNGAPI
1074 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1075     png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1076     png_progressive_end_ptr end_fn)
1077 {
1078    if (png_ptr == NULL)
1079       return;
1080
1081    png_ptr->info_fn = info_fn;
1082    png_ptr->row_fn = row_fn;
1083    png_ptr->end_fn = end_fn;
1084
1085    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1086 }
1087
1088 png_voidp PNGAPI
1089 png_get_progressive_ptr(png_const_structrp png_ptr)
1090 {
1091    if (png_ptr == NULL)
1092       return (NULL);
1093
1094    return png_ptr->io_ptr;
1095 }
1096 #endif /* PROGRESSIVE_READ */