pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   3  *
   4  * Last changed in libpng 1.4.3 [June 26, 2010]
   5  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  */
  13
  14 #define PNG_NO_PEDANTIC_WARNINGS
  15 #include "png.h"
  16 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  17 #include "pngpriv.h"
  18
  19 /* Push model modes */
  20 #define PNG_READ_SIG_MODE   0
  21 #define PNG_READ_CHUNK_MODE 1
  22 #define PNG_READ_IDAT_MODE  2
  23 #define PNG_SKIP_MODE       3
  24 #define PNG_READ_tEXt_MODE  4
  25 #define PNG_READ_zTXt_MODE  5
  26 #define PNG_READ_DONE_MODE  6
  27 #define PNG_READ_iTXt_MODE  7
  28 #define PNG_ERROR_MODE      8
  29
  30 void PNGAPI
  31 png_process_data(png_structp png_ptr, png_infop info_ptr,
  32    png_bytep buffer, png_size_t buffer_size)
  33 {
  34    if (png_ptr == NULL || info_ptr == NULL)
  35       return;
  36
  37    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  38
  39    while (png_ptr->buffer_size)
  40    {
  41       png_process_some_data(png_ptr, info_ptr);
  42    }
  43 }
  44
  45 /* What we do with the incoming data depends on what we were previously
  46  * doing before we ran out of data...
  47  */
  48 void /* PRIVATE */
  49 png_process_some_data(png_structp png_ptr, png_infop info_ptr)
  50 {
  51    if (png_ptr == NULL)
  52       return;
  53
  54    switch (png_ptr->process_mode)
  55    {
  56       case PNG_READ_SIG_MODE:
  57       {
  58          png_push_read_sig(png_ptr, info_ptr);
  59          break;
  60       }
  61
  62       case PNG_READ_CHUNK_MODE:
  63       {
  64          png_push_read_chunk(png_ptr, info_ptr);
  65          break;
  66       }
  67
  68       case PNG_READ_IDAT_MODE:
  69       {
  70          png_push_read_IDAT(png_ptr);
  71          break;
  72       }
  73
  74 #ifdef PNG_READ_tEXt_SUPPORTED
  75       case PNG_READ_tEXt_MODE:
  76       {
  77          png_push_read_tEXt(png_ptr, info_ptr);
  78          break;
  79       }
  80
  81 #endif
  82 #ifdef PNG_READ_zTXt_SUPPORTED
  83       case PNG_READ_zTXt_MODE:
  84       {
  85          png_push_read_zTXt(png_ptr, info_ptr);
  86          break;
  87       }
  88
  89 #endif
  90 #ifdef PNG_READ_iTXt_SUPPORTED
  91       case PNG_READ_iTXt_MODE:
  92       {
  93          png_push_read_iTXt(png_ptr, info_ptr);
  94          break;
  95       }
  96
  97 #endif
  98       case PNG_SKIP_MODE:
  99       {
 100          png_push_crc_finish(png_ptr);
 101          break;
 102       }
 103
 104       default:
 105       {
 106          png_ptr->buffer_size = 0;
 107          break;
 108       }
 109    }
 110 }
 111
 112 /* Read any remaining signature bytes from the stream and compare them with
 113  * the correct PNG signature.  It is possible that this routine is called
 114  * with bytes already read from the signature, either because they have been
 115  * checked by the calling application, or because of multiple calls to this
 116  * routine.
 117  */
 118 void /* PRIVATE */
 119 png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
 120 {
 121    png_size_t num_checked = png_ptr->sig_bytes,
 122              num_to_check = 8 - num_checked;
 123
 124    if (png_ptr->buffer_size < num_to_check)
 125    {
 126       num_to_check = png_ptr->buffer_size;
 127    }
 128
 129    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
 130       num_to_check);
 131    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
 132
 133    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 134    {
 135       if (num_checked < 4 &&
 136           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 137          png_error(png_ptr, "Not a PNG file");
 138       else
 139          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 140    }
 141    else
 142    {
 143       if (png_ptr->sig_bytes >= 8)
 144       {
 145          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 146       }
 147    }
 148 }
 149
 150 void /* PRIVATE */
 151 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 152 {
 153       PNG_IHDR;
 154       PNG_IDAT;
 155       PNG_IEND;
 156       PNG_PLTE;
 157 #ifdef PNG_READ_bKGD_SUPPORTED
 158       PNG_bKGD;
 159 #endif
 160 #ifdef PNG_READ_cHRM_SUPPORTED
 161       PNG_cHRM;
 162 #endif
 163 #ifdef PNG_READ_gAMA_SUPPORTED
 164       PNG_gAMA;
 165 #endif
 166 #ifdef PNG_READ_hIST_SUPPORTED
 167       PNG_hIST;
 168 #endif
 169 #ifdef PNG_READ_iCCP_SUPPORTED
 170       PNG_iCCP;
 171 #endif
 172 #ifdef PNG_READ_iTXt_SUPPORTED
 173       PNG_iTXt;
 174 #endif
 175 #ifdef PNG_READ_oFFs_SUPPORTED
 176       PNG_oFFs;
 177 #endif
 178 #ifdef PNG_READ_pCAL_SUPPORTED
 179       PNG_pCAL;
 180 #endif
 181 #ifdef PNG_READ_pHYs_SUPPORTED
 182       PNG_pHYs;
 183 #endif
 184 #ifdef PNG_READ_sBIT_SUPPORTED
 185       PNG_sBIT;
 186 #endif
 187 #ifdef PNG_READ_sCAL_SUPPORTED
 188       PNG_sCAL;
 189 #endif
 190 #ifdef PNG_READ_sRGB_SUPPORTED
 191       PNG_sRGB;
 192 #endif
 193 #ifdef PNG_READ_sPLT_SUPPORTED
 194       PNG_sPLT;
 195 #endif
 196 #ifdef PNG_READ_tEXt_SUPPORTED
 197       PNG_tEXt;
 198 #endif
 199 #ifdef PNG_READ_tIME_SUPPORTED
 200       PNG_tIME;
 201 #endif
 202 #ifdef PNG_READ_tRNS_SUPPORTED
 203       PNG_tRNS;
 204 #endif
 205 #ifdef PNG_READ_zTXt_SUPPORTED
 206       PNG_zTXt;
 207 #endif
 208
 209    /* First we make sure we have enough data for the 4 byte chunk name
 210     * and the 4 byte chunk length before proceeding with decoding the
 211     * chunk data.  To fully decode each of these chunks, we also make
 212     * sure we have enough data in the buffer for the 4 byte CRC at the
 213     * end of every chunk (except IDAT, which is handled separately).
 214     */
 215    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 216    {
 217       png_byte chunk_length[4];
 218
 219       if (png_ptr->buffer_size < 8)
 220       {
 221          png_push_save_buffer(png_ptr);
 222          return;
 223       }
 224
 225       png_push_fill_buffer(png_ptr, chunk_length, 4);
 226       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 227       png_reset_crc(png_ptr);
 228       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 229       png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 230       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 231    }
 232
 233    if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 234      if (png_ptr->mode & PNG_AFTER_IDAT)
 235         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 236
 237    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 238    {
 239       if (png_ptr->push_length != 13)
 240          png_error(png_ptr, "Invalid IHDR length");
 241
 242       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 243       {
 244          png_push_save_buffer(png_ptr);
 245          return;
 246       }
 247
 248       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 249    }
 250
 251    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 252    {
 253       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 254       {
 255          png_push_save_buffer(png_ptr);
 256          return;
 257       }
 258
 259       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 260
 261       png_ptr->process_mode = PNG_READ_DONE_MODE;
 262       png_push_have_end(png_ptr, info_ptr);
 263    }
 264
 265 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 266    else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
 267    {
 268       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 269       {
 270          png_push_save_buffer(png_ptr);
 271          return;
 272       }
 273
 274       if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 275          png_ptr->mode |= PNG_HAVE_IDAT;
 276
 277       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 278
 279       if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 280          png_ptr->mode |= PNG_HAVE_PLTE;
 281
 282       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 283       {
 284          if (!(png_ptr->mode & PNG_HAVE_IHDR))
 285             png_error(png_ptr, "Missing IHDR before IDAT");
 286
 287          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 288                   !(png_ptr->mode & PNG_HAVE_PLTE))
 289             png_error(png_ptr, "Missing PLTE before IDAT");
 290       }
 291    }
 292
 293 #endif
 294    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 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       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 302    }
 303
 304    else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 305    {
 306       /* If we reach an IDAT chunk, this means we have read all of the
 307        * header chunks, and we can start reading the image (or if this
 308        * is called after the image has been read - we have an error).
 309        */
 310
 311       if (!(png_ptr->mode & PNG_HAVE_IHDR))
 312          png_error(png_ptr, "Missing IHDR before IDAT");
 313
 314       else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 315           !(png_ptr->mode & PNG_HAVE_PLTE))
 316          png_error(png_ptr, "Missing PLTE before IDAT");
 317
 318       if (png_ptr->mode & PNG_HAVE_IDAT)
 319       {
 320          if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
 321             if (png_ptr->push_length == 0)
 322                return;
 323
 324          if (png_ptr->mode & PNG_AFTER_IDAT)
 325             png_benign_error(png_ptr, "Too many IDATs found");
 326       }
 327
 328       png_ptr->idat_size = png_ptr->push_length;
 329       png_ptr->mode |= PNG_HAVE_IDAT;
 330       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 331       png_push_have_info(png_ptr, info_ptr);
 332       png_ptr->zstream.avail_out =
 333           (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
 334           png_ptr->iwidth) + 1;
 335       png_ptr->zstream.next_out = png_ptr->row_buf;
 336       return;
 337    }
 338
 339 #ifdef PNG_READ_gAMA_SUPPORTED
 340    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 341    {
 342       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 343       {
 344          png_push_save_buffer(png_ptr);
 345          return;
 346       }
 347
 348       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 349    }
 350
 351 #endif
 352 #ifdef PNG_READ_sBIT_SUPPORTED
 353    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 354    {
 355       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 356       {
 357          png_push_save_buffer(png_ptr);
 358          return;
 359       }
 360
 361       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 362    }
 363
 364 #endif
 365 #ifdef PNG_READ_cHRM_SUPPORTED
 366    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 367    {
 368       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 369       {
 370          png_push_save_buffer(png_ptr);
 371          return;
 372       }
 373
 374       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 375    }
 376
 377 #endif
 378 #ifdef PNG_READ_sRGB_SUPPORTED
 379    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
 380    {
 381       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 382       {
 383          png_push_save_buffer(png_ptr);
 384          return;
 385       }
 386
 387       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 388    }
 389
 390 #endif
 391 #ifdef PNG_READ_iCCP_SUPPORTED
 392    else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
 393    {
 394       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 395       {
 396          png_push_save_buffer(png_ptr);
 397          return;
 398       }
 399
 400       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
 401    }
 402
 403 #endif
 404 #ifdef PNG_READ_sPLT_SUPPORTED
 405    else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
 406    {
 407       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 408       {
 409          png_push_save_buffer(png_ptr);
 410          return;
 411       }
 412
 413       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
 414    }
 415
 416 #endif
 417 #ifdef PNG_READ_tRNS_SUPPORTED
 418    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 419    {
 420       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 421       {
 422          png_push_save_buffer(png_ptr);
 423          return;
 424       }
 425
 426       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 427    }
 428
 429 #endif
 430 #ifdef PNG_READ_bKGD_SUPPORTED
 431    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 432    {
 433       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 434       {
 435          png_push_save_buffer(png_ptr);
 436          return;
 437       }
 438
 439       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 440    }
 441
 442 #endif
 443 #ifdef PNG_READ_hIST_SUPPORTED
 444    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 445    {
 446       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 447       {
 448          png_push_save_buffer(png_ptr);
 449          return;
 450       }
 451
 452       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 453    }
 454
 455 #endif
 456 #ifdef PNG_READ_pHYs_SUPPORTED
 457    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 458    {
 459       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 460       {
 461          png_push_save_buffer(png_ptr);
 462          return;
 463       }
 464
 465       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 466    }
 467
 468 #endif
 469 #ifdef PNG_READ_oFFs_SUPPORTED
 470    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
 471    {
 472       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 473       {
 474          png_push_save_buffer(png_ptr);
 475          return;
 476       }
 477
 478       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 479    }
 480 #endif
 481
 482 #ifdef PNG_READ_pCAL_SUPPORTED
 483    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
 484    {
 485       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 486       {
 487          png_push_save_buffer(png_ptr);
 488          return;
 489       }
 490
 491       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 492    }
 493
 494 #endif
 495 #ifdef PNG_READ_sCAL_SUPPORTED
 496    else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
 497    {
 498       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 499       {
 500          png_push_save_buffer(png_ptr);
 501          return;
 502       }
 503
 504       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
 505    }
 506
 507 #endif
 508 #ifdef PNG_READ_tIME_SUPPORTED
 509    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 510    {
 511       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 512       {
 513          png_push_save_buffer(png_ptr);
 514          return;
 515       }
 516
 517       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 518    }
 519
 520 #endif
 521 #ifdef PNG_READ_tEXt_SUPPORTED
 522    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 523    {
 524       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 525       {
 526          png_push_save_buffer(png_ptr);
 527          return;
 528       }
 529
 530       png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 531    }
 532
 533 #endif
 534 #ifdef PNG_READ_zTXt_SUPPORTED
 535    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 536    {
 537       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 538       {
 539          png_push_save_buffer(png_ptr);
 540          return;
 541       }
 542
 543       png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 544    }
 545
 546 #endif
 547 #ifdef PNG_READ_iTXt_SUPPORTED
 548    else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
 549    {
 550       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 551       {
 552          png_push_save_buffer(png_ptr);
 553          return;
 554       }
 555
 556       png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
 557    }
 558
 559 #endif
 560    else
 561    {
 562       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 563       {
 564          png_push_save_buffer(png_ptr);
 565          return;
 566       }
 567       png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 568    }
 569
 570    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 571 }
 572
 573 void /* PRIVATE */
 574 png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
 575 {
 576    png_ptr->process_mode = PNG_SKIP_MODE;
 577    png_ptr->skip_length = skip;
 578 }
 579
 580 void /* PRIVATE */
 581 png_push_crc_finish(png_structp png_ptr)
 582 {
 583    if (png_ptr->skip_length && png_ptr->save_buffer_size)
 584    {
 585       png_size_t save_size;
 586
 587       if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
 588          save_size = (png_size_t)png_ptr->skip_length;
 589       else
 590          save_size = png_ptr->save_buffer_size;
 591
 592       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 593
 594       png_ptr->skip_length -= save_size;
 595       png_ptr->buffer_size -= save_size;
 596       png_ptr->save_buffer_size -= save_size;
 597       png_ptr->save_buffer_ptr += save_size;
 598    }
 599    if (png_ptr->skip_length && png_ptr->current_buffer_size)
 600    {
 601       png_size_t save_size;
 602
 603       if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
 604          save_size = (png_size_t)png_ptr->skip_length;
 605       else
 606          save_size = png_ptr->current_buffer_size;
 607
 608       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 609
 610       png_ptr->skip_length -= save_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    if (!png_ptr->skip_length)
 616    {
 617       if (png_ptr->buffer_size < 4)
 618       {
 619          png_push_save_buffer(png_ptr);
 620          return;
 621       }
 622
 623       png_crc_finish(png_ptr, 0);
 624       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 625    }
 626 }
 627
 628 void PNGAPI
 629 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 630 {
 631    png_bytep ptr;
 632
 633    if (png_ptr == NULL)
 634       return;
 635
 636    ptr = buffer;
 637    if (png_ptr->save_buffer_size)
 638    {
 639       png_size_t save_size;
 640
 641       if (length < png_ptr->save_buffer_size)
 642          save_size = length;
 643       else
 644          save_size = png_ptr->save_buffer_size;
 645
 646       png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 647       length -= save_size;
 648       ptr += save_size;
 649       png_ptr->buffer_size -= save_size;
 650       png_ptr->save_buffer_size -= save_size;
 651       png_ptr->save_buffer_ptr += save_size;
 652    }
 653    if (length && png_ptr->current_buffer_size)
 654    {
 655       png_size_t save_size;
 656
 657       if (length < png_ptr->current_buffer_size)
 658          save_size = length;
 659
 660       else
 661          save_size = png_ptr->current_buffer_size;
 662
 663       png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 664       png_ptr->buffer_size -= save_size;
 665       png_ptr->current_buffer_size -= save_size;
 666       png_ptr->current_buffer_ptr += save_size;
 667    }
 668 }
 669
 670 void /* PRIVATE */
 671 png_push_save_buffer(png_structp png_ptr)
 672 {
 673    if (png_ptr->save_buffer_size)
 674    {
 675       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 676       {
 677          png_size_t i, istop;
 678          png_bytep sp;
 679          png_bytep dp;
 680
 681          istop = png_ptr->save_buffer_size;
 682          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 683             i < istop; i++, sp++, dp++)
 684          {
 685             *dp = *sp;
 686          }
 687       }
 688    }
 689    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 690       png_ptr->save_buffer_max)
 691    {
 692       png_size_t new_max;
 693       png_bytep old_buffer;
 694
 695       if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
 696          (png_ptr->current_buffer_size + 256))
 697       {
 698         png_error(png_ptr, "Potential overflow of save_buffer");
 699       }
 700
 701       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 702       old_buffer = png_ptr->save_buffer;
 703       png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
 704          (png_size_t)new_max);
 705       if (png_ptr->save_buffer == NULL)
 706       {
 707         png_free(png_ptr, old_buffer);
 708         png_error(png_ptr, "Insufficient memory for save_buffer");
 709       }
 710       png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 711       png_free(png_ptr, old_buffer);
 712       png_ptr->save_buffer_max = new_max;
 713    }
 714    if (png_ptr->current_buffer_size)
 715    {
 716       png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 717          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 718       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 719       png_ptr->current_buffer_size = 0;
 720    }
 721    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 722    png_ptr->buffer_size = 0;
 723 }
 724
 725 void /* PRIVATE */
 726 png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 727    png_size_t buffer_length)
 728 {
 729    png_ptr->current_buffer = buffer;
 730    png_ptr->current_buffer_size = buffer_length;
 731    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 732    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 733 }
 734
 735 void /* PRIVATE */
 736 png_push_read_IDAT(png_structp png_ptr)
 737 {
 738    PNG_IDAT;
 739    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 740    {
 741       png_byte chunk_length[4];
 742
 743       if (png_ptr->buffer_size < 8)
 744       {
 745          png_push_save_buffer(png_ptr);
 746          return;
 747       }
 748
 749       png_push_fill_buffer(png_ptr, chunk_length, 4);
 750       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
 751       png_reset_crc(png_ptr);
 752       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 753       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 754
 755       if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 756       {
 757          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 758          if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 759             png_error(png_ptr, "Not enough compressed data");
 760          return;
 761       }
 762
 763       png_ptr->idat_size = png_ptr->push_length;
 764    }
 765    if (png_ptr->idat_size && png_ptr->save_buffer_size)
 766    {
 767       png_size_t save_size;
 768
 769       if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
 770       {
 771          save_size = (png_size_t)png_ptr->idat_size;
 772
 773          /* Check for overflow */
 774          if ((png_uint_32)save_size != png_ptr->idat_size)
 775             png_error(png_ptr, "save_size overflowed in pngpread");
 776       }
 777       else
 778          save_size = png_ptr->save_buffer_size;
 779
 780       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 781
 782       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 783
 784       png_ptr->idat_size -= save_size;
 785       png_ptr->buffer_size -= save_size;
 786       png_ptr->save_buffer_size -= save_size;
 787       png_ptr->save_buffer_ptr += save_size;
 788    }
 789    if (png_ptr->idat_size && png_ptr->current_buffer_size)
 790    {
 791       png_size_t save_size;
 792
 793       if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
 794       {
 795          save_size = (png_size_t)png_ptr->idat_size;
 796
 797          /* Check for overflow */
 798          if ((png_uint_32)save_size != png_ptr->idat_size)
 799             png_error(png_ptr, "save_size overflowed in pngpread");
 800       }
 801       else
 802          save_size = png_ptr->current_buffer_size;
 803
 804       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 805
 806       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 807
 808       png_ptr->idat_size -= save_size;
 809       png_ptr->buffer_size -= save_size;
 810       png_ptr->current_buffer_size -= save_size;
 811       png_ptr->current_buffer_ptr += save_size;
 812    }
 813    if (!png_ptr->idat_size)
 814    {
 815       if (png_ptr->buffer_size < 4)
 816       {
 817          png_push_save_buffer(png_ptr);
 818          return;
 819       }
 820
 821       png_crc_finish(png_ptr, 0);
 822       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 823       png_ptr->mode |= PNG_AFTER_IDAT;
 824    }
 825 }
 826
 827 void /* PRIVATE */
 828 png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 829    png_size_t buffer_length)
 830 {
 831    /* The caller checks for a non-zero buffer length. */
 832    if (!(buffer_length > 0) || buffer == NULL)
 833       png_error(png_ptr, "No IDAT data (internal error)");
 834
 835    /* This routine must process all the data it has been given
 836     * before returning, calling the row callback as required to
 837     * handle the uncompressed results.
 838     */
 839    png_ptr->zstream.next_in = buffer;
 840    png_ptr->zstream.avail_in = (uInt)buffer_length;
 841
 842    /* Keep going until the decompressed data is all processed
 843     * or the stream marked as finished.
 844     */
 845    while (png_ptr->zstream.avail_in > 0 &&
 846           !(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 847    {
 848       int ret;
 849
 850       /* We have data for zlib, but we must check that zlib
 851        * has somewhere to put the results.  It doesn't matter
 852        * if we don't expect any results -- it may be the input
 853        * data is just the LZ end code.
 854        */
 855       if (!(png_ptr->zstream.avail_out > 0))
 856       {
 857          png_ptr->zstream.avail_out =
 858              (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
 859              png_ptr->iwidth) + 1;
 860          png_ptr->zstream.next_out = png_ptr->row_buf;
 861       }
 862
 863       /* Using Z_SYNC_FLUSH here means that an unterminated
 864        * LZ stream can still be handled (a stream with a missing
 865        * end code), otherwise (Z_NO_FLUSH) a future zlib
 866        * implementation might defer output and, therefore,
 867        * change the current behavior.  (See comments in inflate.c
 868        * for why this doesn't happen at present with zlib 1.2.5.)
 869        */
 870       ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
 871
 872       /* Check for any failure before proceeding. */
 873       if (ret != Z_OK && ret != Z_STREAM_END)
 874       {
 875          /* Terminate the decompression. */
 876          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 877
 878          /* This may be a truncated stream (missing or
 879           * damaged end code).  Treat that as a warning.
 880           */
 881          if (png_ptr->row_number >= png_ptr->num_rows ||
 882              png_ptr->pass > 6)
 883             png_warning(png_ptr, "Truncated compressed data in IDAT");
 884          else
 885             png_error(png_ptr, "Decompression error in IDAT");
 886
 887          /* Skip the check on unprocessed input */
 888          return;
 889       }
 890
 891       /* Did inflate output any data? */
 892       if (png_ptr->zstream.next_out != png_ptr->row_buf)
 893       {
 894          /* Is this unexpected data after the last row?
 895           * If it is, artificially terminate the LZ output
 896           * here.
 897           */
 898          if (png_ptr->row_number >= png_ptr->num_rows ||
 899              png_ptr->pass > 6)
 900          {
 901             /* Extra data. */
 902             png_warning(png_ptr, "Extra compressed data in IDAT");
 903             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 904             /* Do no more processing; skip the unprocessed
 905              * input check below.
 906              */
 907             return;
 908          }
 909
 910          /* Do we have a complete row? */
 911          if (png_ptr->zstream.avail_out == 0)
 912             png_push_process_row(png_ptr);
 913       }
 914
 915       /* And check for the end of the stream. */
 916       if (ret == Z_STREAM_END)
 917          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 918    }
 919
 920    /* All the data should have been processed, if anything
 921     * is left at this point we have bytes of IDAT data
 922     * after the zlib end code.
 923     */
 924    if (png_ptr->zstream.avail_in > 0)
 925       png_warning(png_ptr, "Extra compression data");
 926 }
 927
 928 void /* PRIVATE */
 929 png_push_process_row(png_structp png_ptr)
 930 {
 931    png_ptr->row_info.color_type = png_ptr->color_type;
 932    png_ptr->row_info.width = png_ptr->iwidth;
 933    png_ptr->row_info.channels = png_ptr->channels;
 934    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
 935    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
 936
 937    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
 938        png_ptr->row_info.width);
 939
 940    png_read_filter_row(png_ptr, &(png_ptr->row_info),
 941        png_ptr->row_buf + 1, png_ptr->prev_row + 1,
 942        (int)(png_ptr->row_buf[0]));
 943
 944    png_memcpy(png_ptr->prev_row, png_ptr->row_buf, png_ptr->rowbytes + 1);
 945
 946    if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
 947       png_do_read_transformations(png_ptr);
 948
 949 #ifdef PNG_READ_INTERLACING_SUPPORTED
 950    /* Blow up interlaced rows to full size */
 951    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 952    {
 953       if (png_ptr->pass < 6)
 954 /*       old interface (pre-1.0.9):
 955          png_do_read_interlace(&(png_ptr->row_info),
 956              png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 957  */
 958          png_do_read_interlace(png_ptr);
 959
 960     switch (png_ptr->pass)
 961     {
 962          case 0:
 963          {
 964             int i;
 965             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 966             {
 967                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 968                png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
 969             }
 970
 971             if (png_ptr->pass == 2) /* Pass 1 might be empty */
 972             {
 973                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 974                {
 975                   png_push_have_row(png_ptr, NULL);
 976                   png_read_push_finish_row(png_ptr);
 977                }
 978             }
 979
 980             if (png_ptr->pass == 4 && png_ptr->height <= 4)
 981             {
 982                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 983                {
 984                   png_push_have_row(png_ptr, NULL);
 985                   png_read_push_finish_row(png_ptr);
 986                }
 987             }
 988
 989             if (png_ptr->pass == 6 && png_ptr->height <= 4)
 990             {
 991                   png_push_have_row(png_ptr, NULL);
 992                 png_read_push_finish_row(png_ptr);
 993             }
 994
 995             break;
 996          }
 997
 998          case 1:
 999          {
1000             int i;
1001             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
1002             {
1003                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1004                png_read_push_finish_row(png_ptr);
1005             }
1006
1007             if (png_ptr->pass == 2) /* Skip top 4 generated rows */
1008             {
1009                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1010                {
1011                   png_push_have_row(png_ptr, NULL);
1012                   png_read_push_finish_row(png_ptr);
1013                }
1014             }
1015
1016             break;
1017          }
1018
1019          case 2:
1020          {
1021             int i;
1022
1023             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1024             {
1025                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1026                png_read_push_finish_row(png_ptr);
1027             }
1028
1029             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1030             {
1031                   png_push_have_row(png_ptr, NULL);
1032                png_read_push_finish_row(png_ptr);
1033             }
1034
1035             if (png_ptr->pass == 4) /* Pass 3 might be empty */
1036             {
1037                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1038                {
1039                   png_push_have_row(png_ptr, NULL);
1040                   png_read_push_finish_row(png_ptr);
1041                }
1042             }
1043
1044             break;
1045          }
1046
1047          case 3:
1048          {
1049             int i;
1050
1051             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
1052             {
1053                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1054                png_read_push_finish_row(png_ptr);
1055             }
1056
1057             if (png_ptr->pass == 4) /* Skip top two generated rows */
1058             {
1059                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1060                {
1061                   png_push_have_row(png_ptr, NULL);
1062                   png_read_push_finish_row(png_ptr);
1063                }
1064             }
1065
1066             break;
1067          }
1068
1069          case 4:
1070          {
1071             int i;
1072
1073             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1074             {
1075                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1076                png_read_push_finish_row(png_ptr);
1077             }
1078
1079             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1080             {
1081                   png_push_have_row(png_ptr, NULL);
1082                png_read_push_finish_row(png_ptr);
1083             }
1084
1085             if (png_ptr->pass == 6) /* Pass 5 might be empty */
1086             {
1087                   png_push_have_row(png_ptr, NULL);
1088                png_read_push_finish_row(png_ptr);
1089             }
1090
1091             break;
1092          }
1093
1094          case 5:
1095          {
1096             int i;
1097
1098             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
1099             {
1100                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1101                png_read_push_finish_row(png_ptr);
1102             }
1103
1104             if (png_ptr->pass == 6) /* Skip top generated row */
1105             {
1106                   png_push_have_row(png_ptr, NULL);
1107                png_read_push_finish_row(png_ptr);
1108             }
1109
1110             break;
1111          }
1112          case 6:
1113          {
1114             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1115             png_read_push_finish_row(png_ptr);
1116
1117             if (png_ptr->pass != 6)
1118                break;
1119
1120                   png_push_have_row(png_ptr, NULL);
1121             png_read_push_finish_row(png_ptr);
1122          }
1123       }
1124    }
1125    else
1126 #endif
1127    {
1128       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1129       png_read_push_finish_row(png_ptr);
1130    }
1131 }
1132
1133 void /* PRIVATE */
1134 png_read_push_finish_row(png_structp png_ptr)
1135 {
1136    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1137
1138    /* Start of interlace block */
1139    PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
1140
1141    /* Offset to next interlace block */
1142    PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
1143
1144    /* Start of interlace block in the y direction */
1145    PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
1146
1147    /* Offset to next interlace block in the y direction */
1148    PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
1149
1150    /* Height of interlace block.  This is not currently used - if you need
1151     * it, uncomment it here and in png.h
1152    PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
1153    */
1154
1155    png_ptr->row_number++;
1156    if (png_ptr->row_number < png_ptr->num_rows)
1157       return;
1158
1159 #ifdef PNG_READ_INTERLACING_SUPPORTED
1160    if (png_ptr->interlaced)
1161    {
1162       png_ptr->row_number = 0;
1163       png_memset(png_ptr->prev_row, 0,
1164          png_ptr->rowbytes + 1);
1165       do
1166       {
1167          png_ptr->pass++;
1168          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1169              (png_ptr->pass == 3 && png_ptr->width < 3) ||
1170              (png_ptr->pass == 5 && png_ptr->width < 2))
1171            png_ptr->pass++;
1172
1173          if (png_ptr->pass > 7)
1174             png_ptr->pass--;
1175
1176          if (png_ptr->pass >= 7)
1177             break;
1178
1179          png_ptr->iwidth = (png_ptr->width +
1180             png_pass_inc[png_ptr->pass] - 1 -
1181             png_pass_start[png_ptr->pass]) /
1182             png_pass_inc[png_ptr->pass];
1183
1184          if (png_ptr->transformations & PNG_INTERLACE)
1185             break;
1186
1187          png_ptr->num_rows = (png_ptr->height +
1188             png_pass_yinc[png_ptr->pass] - 1 -
1189             png_pass_ystart[png_ptr->pass]) /
1190             png_pass_yinc[png_ptr->pass];
1191
1192       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1193    }
1194 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1195 }
1196
1197 #ifdef PNG_READ_tEXt_SUPPORTED
1198 void /* PRIVATE */
1199 png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1200    length)
1201 {
1202    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1203       {
1204          png_error(png_ptr, "Out of place tEXt");
1205          info_ptr = info_ptr; /* To quiet some compiler warnings */
1206       }
1207
1208 #ifdef PNG_MAX_MALLOC_64K
1209    png_ptr->skip_length = 0;  /* This may not be necessary */
1210
1211    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
1212    {
1213       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
1214       png_ptr->skip_length = length - (png_uint_32)65535L;
1215       length = (png_uint_32)65535L;
1216    }
1217 #endif
1218
1219    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1220       (png_size_t)(length + 1));
1221    png_ptr->current_text[length] = '\0';
1222    png_ptr->current_text_ptr = png_ptr->current_text;
1223    png_ptr->current_text_size = (png_size_t)length;
1224    png_ptr->current_text_left = (png_size_t)length;
1225    png_ptr->process_mode = PNG_READ_tEXt_MODE;
1226 }
1227
1228 void /* PRIVATE */
1229 png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
1230 {
1231    if (png_ptr->buffer_size && png_ptr->current_text_left)
1232    {
1233       png_size_t text_size;
1234
1235       if (png_ptr->buffer_size < png_ptr->current_text_left)
1236          text_size = png_ptr->buffer_size;
1237
1238       else
1239          text_size = png_ptr->current_text_left;
1240
1241       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1242       png_ptr->current_text_left -= text_size;
1243       png_ptr->current_text_ptr += text_size;
1244    }
1245    if (!(png_ptr->current_text_left))
1246    {
1247       png_textp text_ptr;
1248       png_charp text;
1249       png_charp key;
1250       int ret;
1251
1252       if (png_ptr->buffer_size < 4)
1253       {
1254          png_push_save_buffer(png_ptr);
1255          return;
1256       }
1257
1258       png_push_crc_finish(png_ptr);
1259
1260 #ifdef PNG_MAX_MALLOC_64K
1261       if (png_ptr->skip_length)
1262          return;
1263 #endif
1264
1265       key = png_ptr->current_text;
1266
1267       for (text = key; *text; text++)
1268          /* Empty loop */ ;
1269
1270       if (text < key + png_ptr->current_text_size)
1271          text++;
1272
1273       text_ptr = (png_textp)png_malloc(png_ptr,
1274          png_sizeof(png_text));
1275       text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
1276       text_ptr->key = key;
1277 #ifdef PNG_iTXt_SUPPORTED
1278       text_ptr->lang = NULL;
1279       text_ptr->lang_key = NULL;
1280 #endif
1281       text_ptr->text = text;
1282
1283       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1284
1285       png_free(png_ptr, key);
1286       png_free(png_ptr, text_ptr);
1287       png_ptr->current_text = NULL;
1288
1289       if (ret)
1290         png_warning(png_ptr, "Insufficient memory to store text chunk");
1291    }
1292 }
1293 #endif
1294
1295 #ifdef PNG_READ_zTXt_SUPPORTED
1296 void /* PRIVATE */
1297 png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1298    length)
1299 {
1300    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1301       {
1302          png_error(png_ptr, "Out of place zTXt");
1303          info_ptr = info_ptr; /* To quiet some compiler warnings */
1304       }
1305
1306 #ifdef PNG_MAX_MALLOC_64K
1307    /* We can't handle zTXt chunks > 64K, since we don't have enough space
1308     * to be able to store the uncompressed data.  Actually, the threshold
1309     * is probably around 32K, but it isn't as definite as 64K is.
1310     */
1311    if (length > (png_uint_32)65535L)
1312    {
1313       png_warning(png_ptr, "zTXt chunk too large to fit in memory");
1314       png_push_crc_skip(png_ptr, length);
1315       return;
1316    }
1317 #endif
1318
1319    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1320       (png_size_t)(length + 1));
1321    png_ptr->current_text[length] = '\0';
1322    png_ptr->current_text_ptr = png_ptr->current_text;
1323    png_ptr->current_text_size = (png_size_t)length;
1324    png_ptr->current_text_left = (png_size_t)length;
1325    png_ptr->process_mode = PNG_READ_zTXt_MODE;
1326 }
1327
1328 void /* PRIVATE */
1329 png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
1330 {
1331    if (png_ptr->buffer_size && png_ptr->current_text_left)
1332    {
1333       png_size_t text_size;
1334
1335       if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left)
1336          text_size = png_ptr->buffer_size;
1337
1338       else
1339          text_size = png_ptr->current_text_left;
1340
1341       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1342       png_ptr->current_text_left -= text_size;
1343       png_ptr->current_text_ptr += text_size;
1344    }
1345    if (!(png_ptr->current_text_left))
1346    {
1347       png_textp text_ptr;
1348       png_charp text;
1349       png_charp key;
1350       int ret;
1351       png_size_t text_size, key_size;
1352
1353       if (png_ptr->buffer_size < 4)
1354       {
1355          png_push_save_buffer(png_ptr);
1356          return;
1357       }
1358
1359       png_push_crc_finish(png_ptr);
1360
1361       key = png_ptr->current_text;
1362
1363       for (text = key; *text; text++)
1364          /* Empty loop */ ;
1365
1366       /* zTXt can't have zero text */
1367       if (text >= key + png_ptr->current_text_size)
1368       {
1369          png_ptr->current_text = NULL;
1370          png_free(png_ptr, key);
1371          return;
1372       }
1373
1374       text++;
1375
1376       if (*text != PNG_TEXT_COMPRESSION_zTXt) /* Check compression byte */
1377       {
1378          png_ptr->current_text = NULL;
1379          png_free(png_ptr, key);
1380          return;
1381       }
1382
1383       text++;
1384
1385       png_ptr->zstream.next_in = (png_bytep )text;
1386       png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size -
1387          (text - key));
1388       png_ptr->zstream.next_out = png_ptr->zbuf;
1389       png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1390
1391       key_size = text - key;
1392       text_size = 0;
1393       text = NULL;
1394       ret = Z_STREAM_END;
1395
1396       while (png_ptr->zstream.avail_in)
1397       {
1398          ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
1399          if (ret != Z_OK && ret != Z_STREAM_END)
1400          {
1401             inflateReset(&png_ptr->zstream);
1402             png_ptr->zstream.avail_in = 0;
1403             png_ptr->current_text = NULL;
1404             png_free(png_ptr, key);
1405             png_free(png_ptr, text);
1406             return;
1407          }
1408          if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END)
1409          {
1410             if (text == NULL)
1411             {
1412                text = (png_charp)png_malloc(png_ptr,
1413                      (png_ptr->zbuf_size
1414                      - png_ptr->zstream.avail_out + key_size + 1));
1415
1416                png_memcpy(text + key_size, png_ptr->zbuf,
1417                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1418
1419                png_memcpy(text, key, key_size);
1420
1421                text_size = key_size + png_ptr->zbuf_size -
1422                   png_ptr->zstream.avail_out;
1423
1424                *(text + text_size) = '\0';
1425             }
1426             else
1427             {
1428                png_charp tmp;
1429
1430                tmp = text;
1431                text = (png_charp)png_malloc(png_ptr, text_size +
1432                   (png_ptr->zbuf_size
1433                   - png_ptr->zstream.avail_out + 1));
1434
1435                png_memcpy(text, tmp, text_size);
1436                png_free(png_ptr, tmp);
1437
1438                png_memcpy(text + text_size, png_ptr->zbuf,
1439                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1440
1441                text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
1442                *(text + text_size) = '\0';
1443             }
1444             if (ret != Z_STREAM_END)
1445             {
1446                png_ptr->zstream.next_out = png_ptr->zbuf;
1447                png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1448             }
1449          }
1450          else
1451          {
1452             break;
1453          }
1454
1455          if (ret == Z_STREAM_END)
1456             break;
1457       }
1458
1459       inflateReset(&png_ptr->zstream);
1460       png_ptr->zstream.avail_in = 0;
1461
1462       if (ret != Z_STREAM_END)
1463       {
1464          png_ptr->current_text = NULL;
1465          png_free(png_ptr, key);
1466          png_free(png_ptr, text);
1467          return;
1468       }
1469
1470       png_ptr->current_text = NULL;
1471       png_free(png_ptr, key);
1472       key = text;
1473       text += key_size;
1474
1475       text_ptr = (png_textp)png_malloc(png_ptr,
1476           png_sizeof(png_text));
1477       text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt;
1478       text_ptr->key = key;
1479 #ifdef PNG_iTXt_SUPPORTED
1480       text_ptr->lang = NULL;
1481       text_ptr->lang_key = NULL;
1482 #endif
1483       text_ptr->text = text;
1484
1485       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1486
1487       png_free(png_ptr, key);
1488       png_free(png_ptr, text_ptr);
1489
1490       if (ret)
1491         png_warning(png_ptr, "Insufficient memory to store text chunk");
1492    }
1493 }
1494 #endif
1495
1496 #ifdef PNG_READ_iTXt_SUPPORTED
1497 void /* PRIVATE */
1498 png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1499    length)
1500 {
1501    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1502       {
1503          png_error(png_ptr, "Out of place iTXt");
1504          info_ptr = info_ptr; /* To quiet some compiler warnings */
1505       }
1506
1507 #ifdef PNG_MAX_MALLOC_64K
1508    png_ptr->skip_length = 0;  /* This may not be necessary */
1509
1510    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
1511    {
1512       png_warning(png_ptr, "iTXt chunk too large to fit in memory");
1513       png_ptr->skip_length = length - (png_uint_32)65535L;
1514       length = (png_uint_32)65535L;
1515    }
1516 #endif
1517
1518    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1519       (png_size_t)(length + 1));
1520    png_ptr->current_text[length] = '\0';
1521    png_ptr->current_text_ptr = png_ptr->current_text;
1522    png_ptr->current_text_size = (png_size_t)length;
1523    png_ptr->current_text_left = (png_size_t)length;
1524    png_ptr->process_mode = PNG_READ_iTXt_MODE;
1525 }
1526
1527 void /* PRIVATE */
1528 png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr)
1529 {
1530
1531    if (png_ptr->buffer_size && png_ptr->current_text_left)
1532    {
1533       png_size_t text_size;
1534
1535       if (png_ptr->buffer_size < png_ptr->current_text_left)
1536          text_size = png_ptr->buffer_size;
1537
1538       else
1539          text_size = png_ptr->current_text_left;
1540
1541       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1542       png_ptr->current_text_left -= text_size;
1543       png_ptr->current_text_ptr += text_size;
1544    }
1545    if (!(png_ptr->current_text_left))
1546    {
1547       png_textp text_ptr;
1548       png_charp key;
1549       int comp_flag;
1550       png_charp lang;
1551       png_charp lang_key;
1552       png_charp text;
1553       int ret;
1554
1555       if (png_ptr->buffer_size < 4)
1556       {
1557          png_push_save_buffer(png_ptr);
1558          return;
1559       }
1560
1561       png_push_crc_finish(png_ptr);
1562
1563 #ifdef PNG_MAX_MALLOC_64K
1564       if (png_ptr->skip_length)
1565          return;
1566 #endif
1567
1568       key = png_ptr->current_text;
1569
1570       for (lang = key; *lang; lang++)
1571          /* Empty loop */ ;
1572
1573       if (lang < key + png_ptr->current_text_size - 3)
1574          lang++;
1575
1576       comp_flag = *lang++;
1577       lang++;     /* Skip comp_type, always zero */
1578
1579       for (lang_key = lang; *lang_key; lang_key++)
1580          /* Empty loop */ ;
1581
1582       lang_key++;        /* Skip NUL separator */
1583
1584       text=lang_key;
1585
1586       if (lang_key < key + png_ptr->current_text_size - 1)
1587       {
1588         for (; *text; text++)
1589            /* Empty loop */ ;
1590       }
1591
1592       if (text < key + png_ptr->current_text_size)
1593          text++;
1594
1595       text_ptr = (png_textp)png_malloc(png_ptr,
1596          png_sizeof(png_text));
1597
1598       text_ptr->compression = comp_flag + 2;
1599       text_ptr->key = key;
1600       text_ptr->lang = lang;
1601       text_ptr->lang_key = lang_key;
1602       text_ptr->text = text;
1603       text_ptr->text_length = 0;
1604       text_ptr->itxt_length = png_strlen(text);
1605
1606       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1607
1608       png_ptr->current_text = NULL;
1609
1610       png_free(png_ptr, text_ptr);
1611       if (ret)
1612          png_warning(png_ptr, "Insufficient memory to store iTXt chunk");
1613    }
1614 }
1615 #endif
1616
1617 /* This function is called when we haven't found a handler for this
1618  * chunk.  If there isn't a problem with the chunk itself (ie a bad chunk
1619  * name or a critical chunk), the chunk is (currently) silently ignored.
1620  */
1621 void /* PRIVATE */
1622 png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
1623    length)
1624 {
1625    png_uint_32 skip = 0;
1626
1627    if (!(png_ptr->chunk_name[0] & 0x20))
1628    {
1629 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
1630       if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1631          PNG_HANDLE_CHUNK_ALWAYS
1632 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1633          && png_ptr->read_user_chunk_fn == NULL
1634 #endif
1635          )
1636 #endif
1637          png_chunk_error(png_ptr, "unknown critical chunk");
1638
1639       info_ptr = info_ptr; /* To quiet some compiler warnings */
1640    }
1641
1642 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
1643    if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
1644    {
1645 #ifdef PNG_MAX_MALLOC_64K
1646       if (length > (png_uint_32)65535L)
1647       {
1648           png_warning(png_ptr, "unknown chunk too large to fit in memory");
1649           skip = length - (png_uint_32)65535L;
1650           length = (png_uint_32)65535L;
1651       }
1652 #endif
1653       png_memcpy((png_charp)png_ptr->unknown_chunk.name,
1654                  (png_charp)png_ptr->chunk_name,
1655                  png_sizeof(png_ptr->unknown_chunk.name));
1656       png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name) - 1]
1657         = '\0';
1658
1659       png_ptr->unknown_chunk.size = (png_size_t)length;
1660
1661       if (length == 0)
1662          png_ptr->unknown_chunk.data = NULL;
1663
1664       else
1665       {
1666          png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr,
1667             (png_size_t)length);
1668          png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
1669       }
1670
1671 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1672       if (png_ptr->read_user_chunk_fn != NULL)
1673       {
1674          /* Callback to user unknown chunk handler */
1675          int ret;
1676          ret = (*(png_ptr->read_user_chunk_fn))
1677            (png_ptr, &png_ptr->unknown_chunk);
1678
1679          if (ret < 0)
1680             png_chunk_error(png_ptr, "error in user chunk");
1681
1682          if (ret == 0)
1683          {
1684             if (!(png_ptr->chunk_name[0] & 0x20))
1685                if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1686                     PNG_HANDLE_CHUNK_ALWAYS)
1687                   png_chunk_error(png_ptr, "unknown critical chunk");
1688             png_set_unknown_chunks(png_ptr, info_ptr,
1689                &png_ptr->unknown_chunk, 1);
1690          }
1691       }
1692
1693       else
1694 #endif
1695         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
1696       png_free(png_ptr, png_ptr->unknown_chunk.data);
1697       png_ptr->unknown_chunk.data = NULL;
1698    }
1699
1700    else
1701 #endif
1702       skip=length;
1703    png_push_crc_skip(png_ptr, skip);
1704 }
1705
1706 void /* PRIVATE */
1707 png_push_have_info(png_structp png_ptr, png_infop info_ptr)
1708 {
1709    if (png_ptr->info_fn != NULL)
1710       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1711 }
1712
1713 void /* PRIVATE */
1714 png_push_have_end(png_structp png_ptr, png_infop info_ptr)
1715 {
1716    if (png_ptr->end_fn != NULL)
1717       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1718 }
1719
1720 void /* PRIVATE */
1721 png_push_have_row(png_structp png_ptr, png_bytep row)
1722 {
1723    if (png_ptr->row_fn != NULL)
1724       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1725          (int)png_ptr->pass);
1726 }
1727
1728 void PNGAPI
1729 png_progressive_combine_row (png_structp png_ptr,
1730    png_bytep old_row, png_bytep new_row)
1731 {
1732    PNG_CONST int FARDATA png_pass_dsp_mask[7] =
1733       {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
1734
1735    if (png_ptr == NULL)
1736       return;
1737
1738    if (new_row != NULL)    /* new_row must == png_ptr->row_buf here. */
1739       png_combine_row(png_ptr, old_row, png_pass_dsp_mask[png_ptr->pass]);
1740 }
1741
1742 void PNGAPI
1743 png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
1744    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1745    png_progressive_end_ptr end_fn)
1746 {
1747    if (png_ptr == NULL)
1748       return;
1749
1750    png_ptr->info_fn = info_fn;
1751    png_ptr->row_fn = row_fn;
1752    png_ptr->end_fn = end_fn;
1753
1754    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1755 }
1756
1757 png_voidp PNGAPI
1758 png_get_progressive_ptr(png_structp png_ptr)
1759 {
1760    if (png_ptr == NULL)
1761       return (NULL);
1762
1763    return png_ptr->io_ptr;
1764 }
1765 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */