compiler/libpng/pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   3  *
   4  * libpng 1.0.10 - March 30, 2001
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1998-2001 Glenn Randers-Pehrson
   7  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   8  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   9  */
  10
  11 #define PNG_INTERNAL
  12 #include "png.h"
  13
  14 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  15
  16 /* push model modes */
  17 #define PNG_READ_SIG_MODE   0
  18 #define PNG_READ_CHUNK_MODE 1
  19 #define PNG_READ_IDAT_MODE  2
  20 #define PNG_SKIP_MODE       3
  21 #define PNG_READ_tEXt_MODE  4
  22 #define PNG_READ_zTXt_MODE  5
  23 #define PNG_READ_DONE_MODE  6
  24 #define PNG_READ_iTXt_MODE  7
  25 #define PNG_ERROR_MODE      8
  26
  27 void PNGAPI
  28 png_process_data(png_structp png_ptr, png_infop info_ptr,
  29    png_bytep buffer, png_size_t buffer_size)
  30 {
  31    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  32
  33    while (png_ptr->buffer_size)
  34    {
  35       png_process_some_data(png_ptr, info_ptr);
  36    }
  37 }
  38
  39 /* What we do with the incoming data depends on what we were previously
  40  * doing before we ran out of data...
  41  */
  42 void /* PRIVATE */
  43 png_process_some_data(png_structp png_ptr, png_infop info_ptr)
  44 {
  45    switch (png_ptr->process_mode)
  46    {
  47       case PNG_READ_SIG_MODE:
  48       {
  49          png_push_read_sig(png_ptr, info_ptr);
  50          break;
  51       }
  52       case PNG_READ_CHUNK_MODE:
  53       {
  54          png_push_read_chunk(png_ptr, info_ptr);
  55          break;
  56       }
  57       case PNG_READ_IDAT_MODE:
  58       {
  59          png_push_read_IDAT(png_ptr);
  60          break;
  61       }
  62 #if defined(PNG_READ_tEXt_SUPPORTED)
  63       case PNG_READ_tEXt_MODE:
  64       {
  65          png_push_read_tEXt(png_ptr, info_ptr);
  66          break;
  67       }
  68 #endif
  69 #if defined(PNG_READ_zTXt_SUPPORTED)
  70       case PNG_READ_zTXt_MODE:
  71       {
  72          png_push_read_zTXt(png_ptr, info_ptr);
  73          break;
  74       }
  75 #endif
  76 #if defined(PNG_READ_iTXt_SUPPORTED)
  77       case PNG_READ_iTXt_MODE:
  78       {
  79          png_push_read_iTXt(png_ptr, info_ptr);
  80          break;
  81       }
  82 #endif
  83       case PNG_SKIP_MODE:
  84       {
  85          png_push_crc_finish(png_ptr);
  86          break;
  87       }
  88       default:
  89       {
  90          png_ptr->buffer_size = 0;
  91          break;
  92       }
  93    }
  94 }
  95
  96 /* Read any remaining signature bytes from the stream and compare them with
  97  * the correct PNG signature.  It is possible that this routine is called
  98  * with bytes already read from the signature, either because they have been
  99  * checked by the calling application, or because of multiple calls to this
 100  * routine.
 101  */
 102 void /* PRIVATE */
 103 png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
 104 {
 105    png_size_t num_checked = png_ptr->sig_bytes,
 106              num_to_check = 8 - num_checked;
 107
 108    if (png_ptr->buffer_size < num_to_check)
 109    {
 110       num_to_check = png_ptr->buffer_size;
 111    }
 112
 113    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
 114       num_to_check);
 115    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes+num_to_check);
 116
 117    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 118    {
 119       if (num_checked < 4 &&
 120           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 121          png_error(png_ptr, "Not a PNG file");
 122       else
 123          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 124    }
 125    else
 126    {
 127       if (png_ptr->sig_bytes >= 8)
 128       {
 129          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 130       }
 131    }
 132 }
 133
 134 void /* PRIVATE */
 135 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 136 {
 137 #ifdef PNG_USE_LOCAL_ARRAYS
 138       PNG_IHDR;
 139       PNG_IDAT;
 140       PNG_IEND;
 141       PNG_PLTE;
 142 #if defined(PNG_READ_bKGD_SUPPORTED)
 143       PNG_bKGD;
 144 #endif
 145 #if defined(PNG_READ_cHRM_SUPPORTED)
 146       PNG_cHRM;
 147 #endif
 148 #if defined(PNG_READ_gAMA_SUPPORTED)
 149       PNG_gAMA;
 150 #endif
 151 #if defined(PNG_READ_hIST_SUPPORTED)
 152       PNG_hIST;
 153 #endif
 154 #if defined(PNG_READ_iCCP_SUPPORTED)
 155       PNG_iCCP;
 156 #endif
 157 #if defined(PNG_READ_iTXt_SUPPORTED)
 158       PNG_iTXt;
 159 #endif
 160 #if defined(PNG_READ_oFFs_SUPPORTED)
 161       PNG_oFFs;
 162 #endif
 163 #if defined(PNG_READ_pCAL_SUPPORTED)
 164       PNG_pCAL;
 165 #endif
 166 #if defined(PNG_READ_pHYs_SUPPORTED)
 167       PNG_pHYs;
 168 #endif
 169 #if defined(PNG_READ_sBIT_SUPPORTED)
 170       PNG_sBIT;
 171 #endif
 172 #if defined(PNG_READ_sCAL_SUPPORTED)
 173       PNG_sCAL;
 174 #endif
 175 #if defined(PNG_READ_sRGB_SUPPORTED)
 176       PNG_sRGB;
 177 #endif
 178 #if defined(PNG_READ_sPLT_SUPPORTED)
 179       PNG_sPLT;
 180 #endif
 181 #if defined(PNG_READ_tEXt_SUPPORTED)
 182       PNG_tEXt;
 183 #endif
 184 #if defined(PNG_READ_tIME_SUPPORTED)
 185       PNG_tIME;
 186 #endif
 187 #if defined(PNG_READ_tRNS_SUPPORTED)
 188       PNG_tRNS;
 189 #endif
 190 #if defined(PNG_READ_zTXt_SUPPORTED)
 191       PNG_zTXt;
 192 #endif
 193 #endif /* PNG_USE_LOCAL_ARRAYS */
 194    /* First we make sure we have enough data for the 4 byte chunk name
 195     * and the 4 byte chunk length before proceeding with decoding the
 196     * chunk data.  To fully decode each of these chunks, we also make
 197     * sure we have enough data in the buffer for the 4 byte CRC at the
 198     * end of every chunk (except IDAT, which is handled separately).
 199     */
 200    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 201    {
 202       png_byte chunk_length[4];
 203
 204       if (png_ptr->buffer_size < 8)
 205       {
 206          png_push_save_buffer(png_ptr);
 207          return;
 208       }
 209
 210       png_push_fill_buffer(png_ptr, chunk_length, 4);
 211       png_ptr->push_length = png_get_uint_32(chunk_length);
 212       png_reset_crc(png_ptr);
 213       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 214       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 215    }
 216
 217    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 218    {
 219       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 220       {
 221          png_push_save_buffer(png_ptr);
 222          return;
 223       }
 224
 225       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 226    }
 227    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 228    {
 229       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 230       {
 231          png_push_save_buffer(png_ptr);
 232          return;
 233       }
 234
 235       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 236    }
 237    else if (!png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
 238    {
 239       /* If we reach an IDAT chunk, this means we have read all of the
 240        * header chunks, and we can start reading the image (or if this
 241        * is called after the image has been read - we have an error).
 242        */
 243       if (png_ptr->mode & PNG_HAVE_IDAT)
 244       {
 245          if (png_ptr->push_length == 0)
 246             return;
 247
 248          if (png_ptr->mode & PNG_AFTER_IDAT)
 249             png_error(png_ptr, "Too many IDAT's found");
 250       }
 251
 252       png_ptr->idat_size = png_ptr->push_length;
 253       png_ptr->mode |= PNG_HAVE_IDAT;
 254       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 255       png_push_have_info(png_ptr, info_ptr);
 256       png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 257       png_ptr->zstream.next_out = png_ptr->row_buf;
 258       return;
 259    }
 260    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 261    {
 262       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 263       {
 264          png_push_save_buffer(png_ptr);
 265          return;
 266       }
 267
 268       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 269       png_ptr->process_mode = PNG_READ_DONE_MODE;
 270       png_push_have_end(png_ptr, info_ptr);
 271    }
 272 #if defined(PNG_READ_gAMA_SUPPORTED)
 273    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 274    {
 275       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 276       {
 277          png_push_save_buffer(png_ptr);
 278          return;
 279       }
 280
 281       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 282    }
 283 #endif
 284 #if defined(PNG_READ_sBIT_SUPPORTED)
 285    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 286    {
 287       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 288       {
 289          png_push_save_buffer(png_ptr);
 290          return;
 291       }
 292
 293       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 294    }
 295 #endif
 296 #if defined(PNG_READ_cHRM_SUPPORTED)
 297    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 298    {
 299       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 300       {
 301          png_push_save_buffer(png_ptr);
 302          return;
 303       }
 304
 305       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 306    }
 307 #endif
 308 #if defined(PNG_READ_sRGB_SUPPORTED)
 309    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
 310    {
 311       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 312       {
 313          png_push_save_buffer(png_ptr);
 314          return;
 315       }
 316
 317       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 318    }
 319 #endif
 320 #if defined(PNG_READ_iCCP_SUPPORTED)
 321    else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
 322    {
 323       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 324       {
 325          png_push_save_buffer(png_ptr);
 326          return;
 327       }
 328
 329       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
 330    }
 331 #endif
 332 #if defined(PNG_READ_sPLT_SUPPORTED)
 333    else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
 334    {
 335       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 336       {
 337          png_push_save_buffer(png_ptr);
 338          return;
 339       }
 340
 341       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
 342    }
 343 #endif
 344 #if defined(PNG_READ_tRNS_SUPPORTED)
 345    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 346    {
 347       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 348       {
 349          png_push_save_buffer(png_ptr);
 350          return;
 351       }
 352
 353       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 354    }
 355 #endif
 356 #if defined(PNG_READ_bKGD_SUPPORTED)
 357    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 358    {
 359       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 360       {
 361          png_push_save_buffer(png_ptr);
 362          return;
 363       }
 364
 365       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 366    }
 367 #endif
 368 #if defined(PNG_READ_hIST_SUPPORTED)
 369    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 370    {
 371       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 372       {
 373          png_push_save_buffer(png_ptr);
 374          return;
 375       }
 376
 377       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 378    }
 379 #endif
 380 #if defined(PNG_READ_pHYs_SUPPORTED)
 381    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 382    {
 383       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 384       {
 385          png_push_save_buffer(png_ptr);
 386          return;
 387       }
 388
 389       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 390    }
 391 #endif
 392 #if defined(PNG_READ_oFFs_SUPPORTED)
 393    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
 394    {
 395       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 396       {
 397          png_push_save_buffer(png_ptr);
 398          return;
 399       }
 400
 401       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 402    }
 403 #endif
 404 #if defined(PNG_READ_pCAL_SUPPORTED)
 405    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 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_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 414    }
 415 #endif
 416 #if defined(PNG_READ_sCAL_SUPPORTED)
 417    else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
 418    {
 419       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 420       {
 421          png_push_save_buffer(png_ptr);
 422          return;
 423       }
 424
 425       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
 426    }
 427 #endif
 428 #if defined(PNG_READ_tIME_SUPPORTED)
 429    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 430    {
 431       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 432       {
 433          png_push_save_buffer(png_ptr);
 434          return;
 435       }
 436
 437       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 438    }
 439 #endif
 440 #if defined(PNG_READ_tEXt_SUPPORTED)
 441    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 442    {
 443       png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 444    }
 445 #endif
 446 #if defined(PNG_READ_zTXt_SUPPORTED)
 447    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 448    {
 449       png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 450    }
 451 #endif
 452 #if defined(PNG_READ_iTXt_SUPPORTED)
 453    else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
 454    {
 455       png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
 456    }
 457 #endif
 458    else
 459    {
 460       png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 461    }
 462
 463    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 464 }
 465
 466 void /* PRIVATE */
 467 png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
 468 {
 469    png_ptr->process_mode = PNG_SKIP_MODE;
 470    png_ptr->skip_length = skip;
 471 }
 472
 473 void /* PRIVATE */
 474 png_push_crc_finish(png_structp png_ptr)
 475 {
 476    if (png_ptr->skip_length && png_ptr->save_buffer_size)
 477    {
 478       png_size_t save_size;
 479
 480       if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
 481          save_size = (png_size_t)png_ptr->skip_length;
 482       else
 483          save_size = png_ptr->save_buffer_size;
 484
 485       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 486
 487       png_ptr->skip_length -= save_size;
 488       png_ptr->buffer_size -= save_size;
 489       png_ptr->save_buffer_size -= save_size;
 490       png_ptr->save_buffer_ptr += save_size;
 491    }
 492    if (png_ptr->skip_length && png_ptr->current_buffer_size)
 493    {
 494       png_size_t save_size;
 495
 496       if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
 497          save_size = (png_size_t)png_ptr->skip_length;
 498       else
 499          save_size = png_ptr->current_buffer_size;
 500
 501       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 502
 503       png_ptr->skip_length -= save_size;
 504       png_ptr->buffer_size -= save_size;
 505       png_ptr->current_buffer_size -= save_size;
 506       png_ptr->current_buffer_ptr += save_size;
 507    }
 508    if (!png_ptr->skip_length)
 509    {
 510       if (png_ptr->buffer_size < 4)
 511       {
 512          png_push_save_buffer(png_ptr);
 513          return;
 514       }
 515
 516       png_crc_finish(png_ptr, 0);
 517       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 518    }
 519 }
 520
 521 void /* PRIVATE */
 522 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 523 {
 524    png_bytep ptr;
 525
 526    ptr = buffer;
 527    if (png_ptr->save_buffer_size)
 528    {
 529       png_size_t save_size;
 530
 531       if (length < png_ptr->save_buffer_size)
 532          save_size = length;
 533       else
 534          save_size = png_ptr->save_buffer_size;
 535
 536       png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 537       length -= save_size;
 538       ptr += save_size;
 539       png_ptr->buffer_size -= save_size;
 540       png_ptr->save_buffer_size -= save_size;
 541       png_ptr->save_buffer_ptr += save_size;
 542    }
 543    if (length && png_ptr->current_buffer_size)
 544    {
 545       png_size_t save_size;
 546
 547       if (length < png_ptr->current_buffer_size)
 548          save_size = length;
 549       else
 550          save_size = png_ptr->current_buffer_size;
 551
 552       png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 553       png_ptr->buffer_size -= save_size;
 554       png_ptr->current_buffer_size -= save_size;
 555       png_ptr->current_buffer_ptr += save_size;
 556    }
 557 }
 558
 559 void /* PRIVATE */
 560 png_push_save_buffer(png_structp png_ptr)
 561 {
 562    if (png_ptr->save_buffer_size)
 563    {
 564       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 565       {
 566          png_size_t i,istop;
 567          png_bytep sp;
 568          png_bytep dp;
 569
 570          istop = png_ptr->save_buffer_size;
 571          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 572             i < istop; i++, sp++, dp++)
 573          {
 574             *dp = *sp;
 575          }
 576       }
 577    }
 578    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 579       png_ptr->save_buffer_max)
 580    {
 581       png_size_t new_max;
 582       png_bytep old_buffer;
 583
 584       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 585       old_buffer = png_ptr->save_buffer;
 586       png_ptr->save_buffer = (png_bytep)png_malloc(png_ptr,
 587          (png_uint_32)new_max);
 588       png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 589       png_free(png_ptr, old_buffer);
 590       png_ptr->save_buffer_max = new_max;
 591    }
 592    if (png_ptr->current_buffer_size)
 593    {
 594       png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 595          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 596       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 597       png_ptr->current_buffer_size = 0;
 598    }
 599    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 600    png_ptr->buffer_size = 0;
 601 }
 602
 603 void /* PRIVATE */
 604 png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 605    png_size_t buffer_length)
 606 {
 607    png_ptr->current_buffer = buffer;
 608    png_ptr->current_buffer_size = buffer_length;
 609    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 610    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 611 }
 612
 613 void /* PRIVATE */
 614 png_push_read_IDAT(png_structp png_ptr)
 615 {
 616 #ifdef PNG_USE_LOCAL_ARRAYS
 617    PNG_IDAT;
 618 #endif
 619    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 620    {
 621       png_byte chunk_length[4];
 622
 623       if (png_ptr->buffer_size < 8)
 624       {
 625          png_push_save_buffer(png_ptr);
 626          return;
 627       }
 628
 629       png_push_fill_buffer(png_ptr, chunk_length, 4);
 630       png_ptr->push_length = png_get_uint_32(chunk_length);
 631
 632       png_reset_crc(png_ptr);
 633       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 634       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 635
 636       if (png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
 637       {
 638          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 639          if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 640             png_error(png_ptr, "Not enough compressed data");
 641          return;
 642       }
 643
 644       png_ptr->idat_size = png_ptr->push_length;
 645    }
 646    if (png_ptr->idat_size && png_ptr->save_buffer_size)
 647    {
 648       png_size_t save_size;
 649
 650       if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
 651       {
 652          save_size = (png_size_t)png_ptr->idat_size;
 653          /* check for overflow */
 654          if((png_uint_32)save_size != png_ptr->idat_size)
 655             png_error(png_ptr, "save_size overflowed in pngpread");
 656       }
 657       else
 658          save_size = png_ptr->save_buffer_size;
 659
 660       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 661       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 662
 663       png_ptr->idat_size -= save_size;
 664       png_ptr->buffer_size -= save_size;
 665       png_ptr->save_buffer_size -= save_size;
 666       png_ptr->save_buffer_ptr += save_size;
 667    }
 668    if (png_ptr->idat_size && png_ptr->current_buffer_size)
 669    {
 670       png_size_t save_size;
 671
 672       if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
 673       {
 674          save_size = (png_size_t)png_ptr->idat_size;
 675          /* check for overflow */
 676          if((png_uint_32)save_size != png_ptr->idat_size)
 677             png_error(png_ptr, "save_size overflowed in pngpread");
 678       }
 679       else
 680          save_size = png_ptr->current_buffer_size;
 681
 682       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 683       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 684
 685       png_ptr->idat_size -= save_size;
 686       png_ptr->buffer_size -= save_size;
 687       png_ptr->current_buffer_size -= save_size;
 688       png_ptr->current_buffer_ptr += save_size;
 689    }
 690    if (!png_ptr->idat_size)
 691    {
 692       if (png_ptr->buffer_size < 4)
 693       {
 694          png_push_save_buffer(png_ptr);
 695          return;
 696       }
 697
 698       png_crc_finish(png_ptr, 0);
 699       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 700    }
 701 }
 702
 703 void /* PRIVATE */
 704 png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 705    png_size_t buffer_length)
 706 {
 707    int ret;
 708
 709    if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
 710       png_error(png_ptr, "Extra compression data");
 711
 712    png_ptr->zstream.next_in = buffer;
 713    png_ptr->zstream.avail_in = (uInt)buffer_length;
 714    for(;;)
 715    {
 716       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 717       if (ret != Z_OK)
 718       {
 719          if (ret == Z_STREAM_END)
 720          {
 721             if (png_ptr->zstream.avail_in)
 722                png_error(png_ptr, "Extra compressed data");
 723             if (!(png_ptr->zstream.avail_out))
 724             {
 725                png_push_process_row(png_ptr);
 726             }
 727
 728             png_ptr->mode |= PNG_AFTER_IDAT;
 729             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 730             break;
 731          }
 732          else if (ret == Z_BUF_ERROR)
 733             break;
 734          else
 735             png_error(png_ptr, "Decompression Error");
 736       }
 737       if (!(png_ptr->zstream.avail_out))
 738       {
 739          png_push_process_row(png_ptr);
 740          png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 741          png_ptr->zstream.next_out = png_ptr->row_buf;
 742       }
 743       else
 744          break;
 745    }
 746 }
 747
 748 void /* PRIVATE */
 749 png_push_process_row(png_structp png_ptr)
 750 {
 751    png_ptr->row_info.color_type = png_ptr->color_type;
 752    png_ptr->row_info.width = png_ptr->iwidth;
 753    png_ptr->row_info.channels = png_ptr->channels;
 754    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
 755    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
 756
 757    png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
 758       (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
 759
 760    png_read_filter_row(png_ptr, &(png_ptr->row_info),
 761       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
 762       (int)(png_ptr->row_buf[0]));
 763
 764    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
 765       png_ptr->rowbytes + 1);
 766
 767    if (png_ptr->transformations)
 768       png_do_read_transformations(png_ptr);
 769
 770 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 771    /* blow up interlaced rows to full size */
 772    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 773    {
 774       if (png_ptr->pass < 6)
 775 /*       old interface (pre-1.0.9):
 776          png_do_read_interlace(&(png_ptr->row_info),
 777             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 778  */
 779          png_do_read_interlace(png_ptr);
 780
 781     switch (png_ptr->pass)
 782     {
 783          case 0:
 784          {
 785             int i;
 786             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 787             {
 788                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 789                png_read_push_finish_row(png_ptr); /* updates png_ptr->pass */
 790             }
 791             if (png_ptr->pass == 2) /* pass 1 might be empty */
 792             {
 793                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 794                {
 795                   png_push_have_row(png_ptr, NULL);
 796                   png_read_push_finish_row(png_ptr);
 797                }
 798             }
 799             if (png_ptr->pass == 4 && png_ptr->height <= 4)
 800             {
 801                 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 802                 {
 803                    png_push_have_row(png_ptr, NULL);
 804                    png_read_push_finish_row(png_ptr);
 805                 }
 806             }
 807             if (png_ptr->pass == 6 && png_ptr->height <= 4)
 808             {
 809                 png_push_have_row(png_ptr, NULL);
 810                 png_read_push_finish_row(png_ptr);
 811             }
 812             break;
 813          }
 814          case 1:
 815          {
 816             int i;
 817             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
 818             {
 819                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 820                png_read_push_finish_row(png_ptr);
 821             }
 822             if (png_ptr->pass == 2) /* skip top 4 generated rows */
 823             {
 824                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 825                {
 826                   png_push_have_row(png_ptr, NULL);
 827                   png_read_push_finish_row(png_ptr);
 828                }
 829             }
 830             break;
 831          }
 832          case 2:
 833          {
 834             int i;
 835             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 836             {
 837                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 838                png_read_push_finish_row(png_ptr);
 839             }
 840             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 841             {
 842                png_push_have_row(png_ptr, NULL);
 843                png_read_push_finish_row(png_ptr);
 844             }
 845             if (png_ptr->pass == 4) /* pass 3 might be empty */
 846             {
 847                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 848                {
 849                   png_push_have_row(png_ptr, NULL);
 850                   png_read_push_finish_row(png_ptr);
 851                }
 852             }
 853             break;
 854          }
 855          case 3:
 856          {
 857             int i;
 858             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
 859             {
 860                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 861                png_read_push_finish_row(png_ptr);
 862             }
 863             if (png_ptr->pass == 4) /* skip top two generated rows */
 864             {
 865                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 866                {
 867                   png_push_have_row(png_ptr, NULL);
 868                   png_read_push_finish_row(png_ptr);
 869                }
 870             }
 871             break;
 872          }
 873          case 4:
 874          {
 875             int i;
 876             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 877             {
 878                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 879                png_read_push_finish_row(png_ptr);
 880             }
 881             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 882             {
 883                png_push_have_row(png_ptr, NULL);
 884                png_read_push_finish_row(png_ptr);
 885             }
 886             if (png_ptr->pass == 6) /* pass 5 might be empty */
 887             {
 888                png_push_have_row(png_ptr, NULL);
 889                png_read_push_finish_row(png_ptr);
 890             }
 891             break;
 892          }
 893          case 5:
 894          {
 895             int i;
 896             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
 897             {
 898                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 899                png_read_push_finish_row(png_ptr);
 900             }
 901             if (png_ptr->pass == 6) /* skip top generated row */
 902             {
 903                png_push_have_row(png_ptr, NULL);
 904                png_read_push_finish_row(png_ptr);
 905             }
 906             break;
 907          }
 908          case 6:
 909          {
 910             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 911             png_read_push_finish_row(png_ptr);
 912             if (png_ptr->pass != 6)
 913                break;
 914             png_push_have_row(png_ptr, NULL);
 915             png_read_push_finish_row(png_ptr);
 916          }
 917       }
 918    }
 919    else
 920 #endif
 921    {
 922       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 923       png_read_push_finish_row(png_ptr);
 924    }
 925 }
 926
 927 void /* PRIVATE */
 928 png_read_push_finish_row(png_structp png_ptr)
 929 {
 930 #ifdef PNG_USE_LOCAL_ARRAYS
 931    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 932
 933    /* start of interlace block */
 934    const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 935
 936    /* offset to next interlace block */
 937    const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 938
 939    /* start of interlace block in the y direction */
 940    const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 941
 942    /* offset to next interlace block in the y direction */
 943    const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 944
 945    /* Width of interlace block.  This is not currently used - if you need
 946     * it, uncomment it here and in png.h
 947    const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
 948    */
 949
 950    /* Height of interlace block.  This is not currently used - if you need
 951     * it, uncomment it here and in png.h
 952    const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
 953    */
 954 #endif
 955
 956    png_ptr->row_number++;
 957    if (png_ptr->row_number < png_ptr->num_rows)
 958       return;
 959
 960    if (png_ptr->interlaced)
 961    {
 962       png_ptr->row_number = 0;
 963       png_memset_check(png_ptr, png_ptr->prev_row, 0,
 964          png_ptr->rowbytes + 1);
 965       do
 966       {
 967          png_ptr->pass++;
 968          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
 969              (png_ptr->pass == 3 && png_ptr->width < 3) ||
 970              (png_ptr->pass == 5 && png_ptr->width < 2))
 971            png_ptr->pass++;
 972
 973          if (png_ptr->pass >= 7)
 974             break;
 975
 976          png_ptr->iwidth = (png_ptr->width +
 977             png_pass_inc[png_ptr->pass] - 1 -
 978             png_pass_start[png_ptr->pass]) /
 979             png_pass_inc[png_ptr->pass];
 980
 981          png_ptr->irowbytes = ((png_ptr->iwidth *
 982             png_ptr->pixel_depth + 7) >> 3) + 1;
 983
 984          if (png_ptr->transformations & PNG_INTERLACE)
 985             break;
 986
 987          png_ptr->num_rows = (png_ptr->height +
 988             png_pass_yinc[png_ptr->pass] - 1 -
 989             png_pass_ystart[png_ptr->pass]) /
 990             png_pass_yinc[png_ptr->pass];
 991
 992       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
 993    }
 994 }
 995
 996 #if defined(PNG_READ_tEXt_SUPPORTED)
 997 void /* PRIVATE */
 998 png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 999 {
1000    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1001       {
1002          png_error(png_ptr, "Out of place tEXt");
1003          /* to quiet some compiler warnings */
1004          if(info_ptr == NULL) return;
1005       }
1006
1007 #ifdef PNG_MAX_MALLOC_64K
1008    png_ptr->skip_length = 0;  /* This may not be necessary */
1009
1010    if (length > (png_uint_32)65535L) /* Can't hold the entire string in memory */
1011    {
1012       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
1013       png_ptr->skip_length = length - (png_uint_32)65535L;
1014       length = (png_uint_32)65535L;
1015    }
1016 #endif
1017
1018    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1019          (png_uint_32)(length+1));
1020    png_ptr->current_text[length] = '\0';
1021    png_ptr->current_text_ptr = png_ptr->current_text;
1022    png_ptr->current_text_size = (png_size_t)length;
1023    png_ptr->current_text_left = (png_size_t)length;
1024    png_ptr->process_mode = PNG_READ_tEXt_MODE;
1025 }
1026
1027 void /* PRIVATE */
1028 png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
1029 {
1030    if (png_ptr->buffer_size && png_ptr->current_text_left)
1031    {
1032       png_size_t text_size;
1033
1034       if (png_ptr->buffer_size < png_ptr->current_text_left)
1035          text_size = png_ptr->buffer_size;
1036       else
1037          text_size = png_ptr->current_text_left;
1038       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1039       png_ptr->current_text_left -= text_size;
1040       png_ptr->current_text_ptr += text_size;
1041    }
1042    if (!(png_ptr->current_text_left))
1043    {
1044       png_textp text_ptr;
1045       png_charp text;
1046       png_charp key;
1047
1048       if (png_ptr->buffer_size < 4)
1049       {
1050          png_push_save_buffer(png_ptr);
1051          return;
1052       }
1053
1054       png_push_crc_finish(png_ptr);
1055
1056 #if defined(PNG_MAX_MALLOC_64K)
1057       if (png_ptr->skip_length)
1058          return;
1059 #endif
1060
1061       key = png_ptr->current_text;
1062       png_ptr->current_text = 0;
1063
1064       for (text = key; *text; text++)
1065          /* empty loop */ ;
1066
1067       if (text != key + png_ptr->current_text_size)
1068          text++;
1069
1070       text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
1071       text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
1072       text_ptr->key = key;
1073 #ifdef PNG_iTXt_SUPPORTED
1074       text_ptr->lang = (char *)NULL;
1075       text_ptr->lang_key = (char *)NULL;
1076 #endif
1077       text_ptr->text = text;
1078
1079       png_set_text(png_ptr, info_ptr, text_ptr, 1);
1080
1081       png_free(png_ptr, key);
1082       png_free(png_ptr, text_ptr);
1083    }
1084 }
1085 #endif
1086
1087 #if defined(PNG_READ_zTXt_SUPPORTED)
1088 void /* PRIVATE */
1089 png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
1090 {
1091    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1092       {
1093          png_error(png_ptr, "Out of place zTXt");
1094          /* to quiet some compiler warnings */
1095          if(info_ptr == NULL) return;
1096       }
1097
1098 #ifdef PNG_MAX_MALLOC_64K
1099    /* We can't handle zTXt chunks > 64K, since we don't have enough space
1100     * to be able to store the uncompressed data.  Actually, the threshold
1101     * is probably around 32K, but it isn't as definite as 64K is.
1102     */
1103    if (length > (png_uint_32)65535L)
1104    {
1105       png_warning(png_ptr, "zTXt chunk too large to fit in memory");
1106       png_push_crc_skip(png_ptr, length);
1107       return;
1108    }
1109 #endif
1110
1111    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1112        (png_uint_32)(length+1));
1113    png_ptr->current_text[length] = '\0';
1114    png_ptr->current_text_ptr = png_ptr->current_text;
1115    png_ptr->current_text_size = (png_size_t)length;
1116    png_ptr->current_text_left = (png_size_t)length;
1117    png_ptr->process_mode = PNG_READ_zTXt_MODE;
1118 }
1119
1120 void /* PRIVATE */
1121 png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
1122 {
1123    if (png_ptr->buffer_size && png_ptr->current_text_left)
1124    {
1125       png_size_t text_size;
1126
1127       if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left)
1128          text_size = png_ptr->buffer_size;
1129       else
1130          text_size = png_ptr->current_text_left;
1131       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1132       png_ptr->current_text_left -= text_size;
1133       png_ptr->current_text_ptr += text_size;
1134    }
1135    if (!(png_ptr->current_text_left))
1136    {
1137       png_textp text_ptr;
1138       png_charp text;
1139       png_charp key;
1140       int ret;
1141       png_size_t text_size, key_size;
1142
1143       if (png_ptr->buffer_size < 4)
1144       {
1145          png_push_save_buffer(png_ptr);
1146          return;
1147       }
1148
1149       png_push_crc_finish(png_ptr);
1150
1151       key = png_ptr->current_text;
1152       png_ptr->current_text = 0;
1153
1154       for (text = key; *text; text++)
1155          /* empty loop */ ;
1156
1157       /* zTXt can't have zero text */
1158       if (text == key + png_ptr->current_text_size)
1159       {
1160          png_free(png_ptr, key);
1161          return;
1162       }
1163
1164       text++;
1165
1166       if (*text != PNG_TEXT_COMPRESSION_zTXt) /* check compression byte */
1167       {
1168          png_free(png_ptr, key);
1169          return;
1170       }
1171
1172       text++;
1173
1174       png_ptr->zstream.next_in = (png_bytep )text;
1175       png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size -
1176          (text - key));
1177       png_ptr->zstream.next_out = png_ptr->zbuf;
1178       png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1179
1180       key_size = text - key;
1181       text_size = 0;
1182       text = NULL;
1183       ret = Z_STREAM_END;
1184
1185       while (png_ptr->zstream.avail_in)
1186       {
1187          ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
1188          if (ret != Z_OK && ret != Z_STREAM_END)
1189          {
1190             inflateReset(&png_ptr->zstream);
1191             png_ptr->zstream.avail_in = 0;
1192             png_free(png_ptr, key);
1193             png_free(png_ptr, text);
1194             return;
1195          }
1196          if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END)
1197          {
1198             if (text == NULL)
1199             {
1200                text = (png_charp)png_malloc(png_ptr,
1201                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out +
1202                      key_size + 1));
1203                png_memcpy(text + key_size, png_ptr->zbuf,
1204                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1205                png_memcpy(text, key, key_size);
1206                text_size = key_size + png_ptr->zbuf_size -
1207                   png_ptr->zstream.avail_out;
1208                *(text + text_size) = '\0';
1209             }
1210             else
1211             {
1212                png_charp tmp;
1213
1214                tmp = text;
1215                text = (png_charp)png_malloc(png_ptr, text_size +
1216                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out
1217                    + 1));
1218                png_memcpy(text, tmp, text_size);
1219                png_free(png_ptr, tmp);
1220                png_memcpy(text + text_size, png_ptr->zbuf,
1221                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1222                text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
1223                *(text + text_size) = '\0';
1224             }
1225             if (ret != Z_STREAM_END)
1226             {
1227                png_ptr->zstream.next_out = png_ptr->zbuf;
1228                png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1229             }
1230          }
1231          else
1232          {
1233             break;
1234          }
1235
1236          if (ret == Z_STREAM_END)
1237             break;
1238       }
1239
1240       inflateReset(&png_ptr->zstream);
1241       png_ptr->zstream.avail_in = 0;
1242
1243       if (ret != Z_STREAM_END)
1244       {
1245          png_free(png_ptr, key);
1246          png_free(png_ptr, text);
1247          return;
1248       }
1249
1250       png_free(png_ptr, key);
1251       key = text;
1252       text += key_size;
1253
1254       text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
1255       text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt;
1256       text_ptr->key = key;
1257 #ifdef PNG_iTXt_SUPPORTED
1258       text_ptr->lang = (char *)NULL;
1259       text_ptr->lang_key = (char *)NULL;
1260 #endif
1261       text_ptr->text = text;
1262
1263       png_set_text(png_ptr, info_ptr, text_ptr, 1);
1264
1265       png_free(png_ptr, key);
1266       png_free(png_ptr, text_ptr);
1267    }
1268 }
1269 #endif
1270
1271 #if defined(PNG_READ_iTXt_SUPPORTED)
1272 void /* PRIVATE */
1273 png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
1274 {
1275    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1276       {
1277          png_error(png_ptr, "Out of place iTXt");
1278          /* to quiet some compiler warnings */
1279          if(info_ptr == NULL) return;
1280       }
1281
1282 #ifdef PNG_MAX_MALLOC_64K
1283    png_ptr->skip_length = 0;  /* This may not be necessary */
1284
1285    if (length > (png_uint_32)65535L) /* Can't hold the entire string in memory */
1286    {
1287       png_warning(png_ptr, "iTXt chunk too large to fit in memory");
1288       png_ptr->skip_length = length - (png_uint_32)65535L;
1289       length = (png_uint_32)65535L;
1290    }
1291 #endif
1292
1293    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1294          (png_uint_32)(length+1));
1295    png_ptr->current_text[length] = '\0';
1296    png_ptr->current_text_ptr = png_ptr->current_text;
1297    png_ptr->current_text_size = (png_size_t)length;
1298    png_ptr->current_text_left = (png_size_t)length;
1299    png_ptr->process_mode = PNG_READ_iTXt_MODE;
1300 }
1301
1302 void /* PRIVATE */
1303 png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr)
1304 {
1305
1306    if (png_ptr->buffer_size && png_ptr->current_text_left)
1307    {
1308       png_size_t text_size;
1309
1310       if (png_ptr->buffer_size < png_ptr->current_text_left)
1311          text_size = png_ptr->buffer_size;
1312       else
1313          text_size = png_ptr->current_text_left;
1314       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1315       png_ptr->current_text_left -= text_size;
1316       png_ptr->current_text_ptr += text_size;
1317    }
1318    if (!(png_ptr->current_text_left))
1319    {
1320       png_textp text_ptr;
1321       png_charp key;
1322       int comp_flag;
1323       png_charp lang;
1324       png_charp lang_key;
1325       png_charp text;
1326
1327       if (png_ptr->buffer_size < 4)
1328       {
1329          png_push_save_buffer(png_ptr);
1330          return;
1331       }
1332
1333       png_push_crc_finish(png_ptr);
1334
1335 #if defined(PNG_MAX_MALLOC_64K)
1336       if (png_ptr->skip_length)
1337          return;
1338 #endif
1339
1340       key = png_ptr->current_text;
1341       png_ptr->current_text = 0;
1342
1343       for (lang = key; *lang; lang++)
1344          /* empty loop */ ;
1345
1346       if (lang != key + png_ptr->current_text_size)
1347          lang++;
1348
1349       comp_flag = *lang++;
1350       lang++;     /* skip comp_type, always zero */
1351
1352       for (lang_key = lang; *lang_key; lang_key++)
1353          /* empty loop */ ;
1354       lang_key++;        /* skip NUL separator */
1355
1356       for (text = lang_key; *text; text++)
1357          /* empty loop */ ;
1358
1359       if (text != key + png_ptr->current_text_size)
1360          text++;
1361
1362       text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
1363       text_ptr->compression = comp_flag + 2;
1364       text_ptr->key = key;
1365       text_ptr->lang = lang;
1366       text_ptr->lang_key = lang_key;
1367       text_ptr->text = text;
1368       text_ptr->text_length = 0;
1369       text_ptr->itxt_length = png_strlen(text);
1370
1371       png_set_text(png_ptr, info_ptr, text_ptr, 1);
1372
1373       png_free(png_ptr, text_ptr);
1374    }
1375 }
1376 #endif
1377
1378 /* This function is called when we haven't found a handler for this
1379  * chunk.  If there isn't a problem with the chunk itself (ie a bad chunk
1380  * name or a critical chunk), the chunk is (currently) silently ignored.
1381  */
1382 void /* PRIVATE */
1383 png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
1384 {
1385    png_uint_32 skip=0;
1386    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
1387
1388    if (!(png_ptr->chunk_name[0] & 0x20))
1389    {
1390 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1391       if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1392            HANDLE_CHUNK_ALWAYS
1393 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
1394            && png_ptr->read_user_chunk_fn == (png_user_chunk_ptr)NULL
1395 #endif
1396          )
1397 #endif
1398          png_chunk_error(png_ptr, "unknown critical chunk");
1399
1400       /* to quiet compiler warnings about unused info_ptr */
1401       if (info_ptr == NULL)
1402          return;
1403    }
1404
1405 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1406    if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
1407    {
1408        png_unknown_chunk chunk;
1409
1410 #ifdef PNG_MAX_MALLOC_64K
1411        if (length > (png_uint_32)65535L)
1412        {
1413            png_warning(png_ptr, "unknown chunk too large to fit in memory");
1414            skip = length - (png_uint_32)65535L;
1415            length = (png_uint_32)65535L;
1416        }
1417 #endif
1418
1419        png_strcpy((png_charp)chunk.name, (png_charp)png_ptr->chunk_name);
1420        chunk.data = (png_bytep)png_malloc(png_ptr, length);
1421        png_crc_read(png_ptr, chunk.data, length);
1422        chunk.size = length;
1423 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
1424        if(png_ptr->read_user_chunk_fn != (png_user_chunk_ptr)NULL)
1425        {
1426           /* callback to user unknown chunk handler */
1427           if ((*(png_ptr->read_user_chunk_fn)) (png_ptr, &chunk) <= 0)
1428           {
1429              if (!(png_ptr->chunk_name[0] & 0x20))
1430                 if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1431                      HANDLE_CHUNK_ALWAYS)
1432                    png_chunk_error(png_ptr, "unknown critical chunk");
1433           }
1434              png_set_unknown_chunks(png_ptr, info_ptr, &chunk, 1);
1435        }
1436        else
1437 #endif
1438           png_set_unknown_chunks(png_ptr, info_ptr, &chunk, 1);
1439        png_free(png_ptr, chunk.data);
1440    }
1441    else
1442 #endif
1443       skip=length;
1444    png_push_crc_skip(png_ptr, skip);
1445 }
1446
1447 void /* PRIVATE */
1448 png_push_have_info(png_structp png_ptr, png_infop info_ptr)
1449 {
1450    if (png_ptr->info_fn != NULL)
1451       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1452 }
1453
1454 void /* PRIVATE */
1455 png_push_have_end(png_structp png_ptr, png_infop info_ptr)
1456 {
1457    if (png_ptr->end_fn != NULL)
1458       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1459 }
1460
1461 void /* PRIVATE */
1462 png_push_have_row(png_structp png_ptr, png_bytep row)
1463 {
1464    if (png_ptr->row_fn != NULL)
1465       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1466          (int)png_ptr->pass);
1467 }
1468
1469 void PNGAPI
1470 png_progressive_combine_row (png_structp png_ptr,
1471    png_bytep old_row, png_bytep new_row)
1472 {
1473 #ifdef PNG_USE_LOCAL_ARRAYS
1474    const int FARDATA png_pass_dsp_mask[7] =
1475       {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
1476 #endif
1477    if (new_row != NULL)    /* new_row must == png_ptr->row_buf here. */
1478       png_combine_row(png_ptr, old_row, png_pass_dsp_mask[png_ptr->pass]);
1479 }
1480
1481 void PNGAPI
1482 png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
1483    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1484    png_progressive_end_ptr end_fn)
1485 {
1486    png_ptr->info_fn = info_fn;
1487    png_ptr->row_fn = row_fn;
1488    png_ptr->end_fn = end_fn;
1489
1490    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1491 }
1492
1493 png_voidp PNGAPI
1494 png_get_progressive_ptr(png_structp png_ptr)
1495 {
1496    return png_ptr->io_ptr;
1497 }
1498
1499 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1500