core/libs/libpng-1.2.18/pngpread.c

   1
   2 /* pngpread.c - read a png file in push mode
   3  *
   4  * Last changed in libpng 1.2.17 May 15, 2007
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1998-2007 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    if(png_ptr == NULL) return;
  32    png_push_restore_buffer(png_ptr, buffer, buffer_size);
  33
  34    while (png_ptr->buffer_size)
  35    {
  36       png_process_some_data(png_ptr, info_ptr);
  37    }
  38 }
  39
  40 /* What we do with the incoming data depends on what we were previously
  41  * doing before we ran out of data...
  42  */
  43 void /* PRIVATE */
  44 png_process_some_data(png_structp png_ptr, png_infop info_ptr)
  45 {
  46    if(png_ptr == NULL) return;
  47    switch (png_ptr->process_mode)
  48    {
  49       case PNG_READ_SIG_MODE:
  50       {
  51          png_push_read_sig(png_ptr, info_ptr);
  52          break;
  53       }
  54       case PNG_READ_CHUNK_MODE:
  55       {
  56          png_push_read_chunk(png_ptr, info_ptr);
  57          break;
  58       }
  59       case PNG_READ_IDAT_MODE:
  60       {
  61          png_push_read_IDAT(png_ptr);
  62          break;
  63       }
  64 #if defined(PNG_READ_tEXt_SUPPORTED)
  65       case PNG_READ_tEXt_MODE:
  66       {
  67          png_push_read_tEXt(png_ptr, info_ptr);
  68          break;
  69       }
  70 #endif
  71 #if defined(PNG_READ_zTXt_SUPPORTED)
  72       case PNG_READ_zTXt_MODE:
  73       {
  74          png_push_read_zTXt(png_ptr, info_ptr);
  75          break;
  76       }
  77 #endif
  78 #if defined(PNG_READ_iTXt_SUPPORTED)
  79       case PNG_READ_iTXt_MODE:
  80       {
  81          png_push_read_iTXt(png_ptr, info_ptr);
  82          break;
  83       }
  84 #endif
  85       case PNG_SKIP_MODE:
  86       {
  87          png_push_crc_finish(png_ptr);
  88          break;
  89       }
  90       default:
  91       {
  92          png_ptr->buffer_size = 0;
  93          break;
  94       }
  95    }
  96 }
  97
  98 /* Read any remaining signature bytes from the stream and compare them with
  99  * the correct PNG signature.  It is possible that this routine is called
 100  * with bytes already read from the signature, either because they have been
 101  * checked by the calling application, or because of multiple calls to this
 102  * routine.
 103  */
 104 void /* PRIVATE */
 105 png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
 106 {
 107    png_size_t num_checked = png_ptr->sig_bytes,
 108              num_to_check = 8 - num_checked;
 109
 110    if (png_ptr->buffer_size < num_to_check)
 111    {
 112       num_to_check = png_ptr->buffer_size;
 113    }
 114
 115    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
 116       num_to_check);
 117    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes+num_to_check);
 118
 119    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
 120    {
 121       if (num_checked < 4 &&
 122           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
 123          png_error(png_ptr, "Not a PNG file");
 124       else
 125          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
 126    }
 127    else
 128    {
 129       if (png_ptr->sig_bytes >= 8)
 130       {
 131          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 132       }
 133    }
 134 }
 135
 136 void /* PRIVATE */
 137 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 138 {
 139 #ifdef PNG_USE_LOCAL_ARRAYS
 140       PNG_IHDR;
 141       PNG_IDAT;
 142       PNG_IEND;
 143       PNG_PLTE;
 144 #if defined(PNG_READ_bKGD_SUPPORTED)
 145       PNG_bKGD;
 146 #endif
 147 #if defined(PNG_READ_cHRM_SUPPORTED)
 148       PNG_cHRM;
 149 #endif
 150 #if defined(PNG_READ_gAMA_SUPPORTED)
 151       PNG_gAMA;
 152 #endif
 153 #if defined(PNG_READ_hIST_SUPPORTED)
 154       PNG_hIST;
 155 #endif
 156 #if defined(PNG_READ_iCCP_SUPPORTED)
 157       PNG_iCCP;
 158 #endif
 159 #if defined(PNG_READ_iTXt_SUPPORTED)
 160       PNG_iTXt;
 161 #endif
 162 #if defined(PNG_READ_oFFs_SUPPORTED)
 163       PNG_oFFs;
 164 #endif
 165 #if defined(PNG_READ_pCAL_SUPPORTED)
 166       PNG_pCAL;
 167 #endif
 168 #if defined(PNG_READ_pHYs_SUPPORTED)
 169       PNG_pHYs;
 170 #endif
 171 #if defined(PNG_READ_sBIT_SUPPORTED)
 172       PNG_sBIT;
 173 #endif
 174 #if defined(PNG_READ_sCAL_SUPPORTED)
 175       PNG_sCAL;
 176 #endif
 177 #if defined(PNG_READ_sRGB_SUPPORTED)
 178       PNG_sRGB;
 179 #endif
 180 #if defined(PNG_READ_sPLT_SUPPORTED)
 181       PNG_sPLT;
 182 #endif
 183 #if defined(PNG_READ_tEXt_SUPPORTED)
 184       PNG_tEXt;
 185 #endif
 186 #if defined(PNG_READ_tIME_SUPPORTED)
 187       PNG_tIME;
 188 #endif
 189 #if defined(PNG_READ_tRNS_SUPPORTED)
 190       PNG_tRNS;
 191 #endif
 192 #if defined(PNG_READ_zTXt_SUPPORTED)
 193       PNG_zTXt;
 194 #endif
 195 #endif /* PNG_USE_LOCAL_ARRAYS */
 196    /* First we make sure we have enough data for the 4 byte chunk name
 197     * and the 4 byte chunk length before proceeding with decoding the
 198     * chunk data.  To fully decode each of these chunks, we also make
 199     * sure we have enough data in the buffer for the 4 byte CRC at the
 200     * end of every chunk (except IDAT, which is handled separately).
 201     */
 202    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 203    {
 204       png_byte chunk_length[4];
 205
 206       if (png_ptr->buffer_size < 8)
 207       {
 208          png_push_save_buffer(png_ptr);
 209          return;
 210       }
 211
 212       png_push_fill_buffer(png_ptr, chunk_length, 4);
 213       png_ptr->push_length = png_get_uint_31(png_ptr,chunk_length);
 214       png_reset_crc(png_ptr);
 215       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 216       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 217    }
 218
 219    if (!png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
 220      if(png_ptr->mode & PNG_AFTER_IDAT)
 221         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 222
 223    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
 224    {
 225       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 226       {
 227          png_push_save_buffer(png_ptr);
 228          return;
 229       }
 230       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
 231    }
 232    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
 233    {
 234       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 235       {
 236          png_push_save_buffer(png_ptr);
 237          return;
 238       }
 239       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 240
 241       png_ptr->process_mode = PNG_READ_DONE_MODE;
 242       png_push_have_end(png_ptr, info_ptr);
 243    }
 244 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 245    else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
 246    {
 247       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 248       {
 249          png_push_save_buffer(png_ptr);
 250          return;
 251       }
 252       if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 253          png_ptr->mode |= PNG_HAVE_IDAT;
 254       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 255       if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 256          png_ptr->mode |= PNG_HAVE_PLTE;
 257       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
 258       {
 259          if (!(png_ptr->mode & PNG_HAVE_IHDR))
 260             png_error(png_ptr, "Missing IHDR before IDAT");
 261          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 262                   !(png_ptr->mode & PNG_HAVE_PLTE))
 263             png_error(png_ptr, "Missing PLTE before IDAT");
 264       }
 265    }
 266 #endif
 267    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
 268    {
 269       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 270       {
 271          png_push_save_buffer(png_ptr);
 272          return;
 273       }
 274       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
 275    }
 276    else if (!png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
 277    {
 278       /* If we reach an IDAT chunk, this means we have read all of the
 279        * header chunks, and we can start reading the image (or if this
 280        * is called after the image has been read - we have an error).
 281        */
 282      if (!(png_ptr->mode & PNG_HAVE_IHDR))
 283        png_error(png_ptr, "Missing IHDR before IDAT");
 284      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 285          !(png_ptr->mode & PNG_HAVE_PLTE))
 286        png_error(png_ptr, "Missing PLTE before IDAT");
 287
 288       if (png_ptr->mode & PNG_HAVE_IDAT)
 289       {
 290          if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
 291            if (png_ptr->push_length == 0)
 292               return;
 293
 294          if (png_ptr->mode & PNG_AFTER_IDAT)
 295             png_error(png_ptr, "Too many IDAT's found");
 296       }
 297
 298       png_ptr->idat_size = png_ptr->push_length;
 299       png_ptr->mode |= PNG_HAVE_IDAT;
 300       png_ptr->process_mode = PNG_READ_IDAT_MODE;
 301       png_push_have_info(png_ptr, info_ptr);
 302       png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 303       png_ptr->zstream.next_out = png_ptr->row_buf;
 304       return;
 305    }
 306 #if defined(PNG_READ_gAMA_SUPPORTED)
 307    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
 308    {
 309       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 310       {
 311          png_push_save_buffer(png_ptr);
 312          return;
 313       }
 314       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
 315    }
 316 #endif
 317 #if defined(PNG_READ_sBIT_SUPPORTED)
 318    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
 319    {
 320       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 321       {
 322          png_push_save_buffer(png_ptr);
 323          return;
 324       }
 325       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
 326    }
 327 #endif
 328 #if defined(PNG_READ_cHRM_SUPPORTED)
 329    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
 330    {
 331       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 332       {
 333          png_push_save_buffer(png_ptr);
 334          return;
 335       }
 336       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
 337    }
 338 #endif
 339 #if defined(PNG_READ_sRGB_SUPPORTED)
 340    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 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       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
 348    }
 349 #endif
 350 #if defined(PNG_READ_iCCP_SUPPORTED)
 351    else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
 352    {
 353       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 354       {
 355          png_push_save_buffer(png_ptr);
 356          return;
 357       }
 358       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
 359    }
 360 #endif
 361 #if defined(PNG_READ_sPLT_SUPPORTED)
 362    else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
 363    {
 364       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 365       {
 366          png_push_save_buffer(png_ptr);
 367          return;
 368       }
 369       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
 370    }
 371 #endif
 372 #if defined(PNG_READ_tRNS_SUPPORTED)
 373    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
 374    {
 375       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 376       {
 377          png_push_save_buffer(png_ptr);
 378          return;
 379       }
 380       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
 381    }
 382 #endif
 383 #if defined(PNG_READ_bKGD_SUPPORTED)
 384    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
 385    {
 386       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 387       {
 388          png_push_save_buffer(png_ptr);
 389          return;
 390       }
 391       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
 392    }
 393 #endif
 394 #if defined(PNG_READ_hIST_SUPPORTED)
 395    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
 396    {
 397       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 398       {
 399          png_push_save_buffer(png_ptr);
 400          return;
 401       }
 402       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
 403    }
 404 #endif
 405 #if defined(PNG_READ_pHYs_SUPPORTED)
 406    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
 407    {
 408       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 409       {
 410          png_push_save_buffer(png_ptr);
 411          return;
 412       }
 413       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
 414    }
 415 #endif
 416 #if defined(PNG_READ_oFFs_SUPPORTED)
 417    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 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       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
 425    }
 426 #endif
 427 #if defined(PNG_READ_pCAL_SUPPORTED)
 428    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
 429    {
 430       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 431       {
 432          png_push_save_buffer(png_ptr);
 433          return;
 434       }
 435       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
 436    }
 437 #endif
 438 #if defined(PNG_READ_sCAL_SUPPORTED)
 439    else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
 440    {
 441       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 442       {
 443          png_push_save_buffer(png_ptr);
 444          return;
 445       }
 446       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
 447    }
 448 #endif
 449 #if defined(PNG_READ_tIME_SUPPORTED)
 450    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
 451    {
 452       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 453       {
 454          png_push_save_buffer(png_ptr);
 455          return;
 456       }
 457       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
 458    }
 459 #endif
 460 #if defined(PNG_READ_tEXt_SUPPORTED)
 461    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
 462    {
 463       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 464       {
 465          png_push_save_buffer(png_ptr);
 466          return;
 467       }
 468       png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
 469    }
 470 #endif
 471 #if defined(PNG_READ_zTXt_SUPPORTED)
 472    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
 473    {
 474       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 475       {
 476          png_push_save_buffer(png_ptr);
 477          return;
 478       }
 479       png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
 480    }
 481 #endif
 482 #if defined(PNG_READ_iTXt_SUPPORTED)
 483    else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 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       png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
 491    }
 492 #endif
 493    else
 494    {
 495       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
 496       {
 497          png_push_save_buffer(png_ptr);
 498          return;
 499       }
 500       png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 501    }
 502
 503    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 504 }
 505
 506 void /* PRIVATE */
 507 png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
 508 {
 509    png_ptr->process_mode = PNG_SKIP_MODE;
 510    png_ptr->skip_length = skip;
 511 }
 512
 513 void /* PRIVATE */
 514 png_push_crc_finish(png_structp png_ptr)
 515 {
 516    if (png_ptr->skip_length && png_ptr->save_buffer_size)
 517    {
 518       png_size_t save_size;
 519
 520       if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
 521          save_size = (png_size_t)png_ptr->skip_length;
 522       else
 523          save_size = png_ptr->save_buffer_size;
 524
 525       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 526
 527       png_ptr->skip_length -= save_size;
 528       png_ptr->buffer_size -= save_size;
 529       png_ptr->save_buffer_size -= save_size;
 530       png_ptr->save_buffer_ptr += save_size;
 531    }
 532    if (png_ptr->skip_length && png_ptr->current_buffer_size)
 533    {
 534       png_size_t save_size;
 535
 536       if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
 537          save_size = (png_size_t)png_ptr->skip_length;
 538       else
 539          save_size = png_ptr->current_buffer_size;
 540
 541       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 542
 543       png_ptr->skip_length -= save_size;
 544       png_ptr->buffer_size -= save_size;
 545       png_ptr->current_buffer_size -= save_size;
 546       png_ptr->current_buffer_ptr += save_size;
 547    }
 548    if (!png_ptr->skip_length)
 549    {
 550       if (png_ptr->buffer_size < 4)
 551       {
 552          png_push_save_buffer(png_ptr);
 553          return;
 554       }
 555
 556       png_crc_finish(png_ptr, 0);
 557       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 558    }
 559 }
 560
 561 void PNGAPI
 562 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 563 {
 564    png_bytep ptr;
 565
 566    if(png_ptr == NULL) return;
 567    ptr = buffer;
 568    if (png_ptr->save_buffer_size)
 569    {
 570       png_size_t save_size;
 571
 572       if (length < png_ptr->save_buffer_size)
 573          save_size = length;
 574       else
 575          save_size = png_ptr->save_buffer_size;
 576
 577       png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
 578       length -= save_size;
 579       ptr += save_size;
 580       png_ptr->buffer_size -= save_size;
 581       png_ptr->save_buffer_size -= save_size;
 582       png_ptr->save_buffer_ptr += save_size;
 583    }
 584    if (length && png_ptr->current_buffer_size)
 585    {
 586       png_size_t save_size;
 587
 588       if (length < png_ptr->current_buffer_size)
 589          save_size = length;
 590       else
 591          save_size = png_ptr->current_buffer_size;
 592
 593       png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
 594       png_ptr->buffer_size -= save_size;
 595       png_ptr->current_buffer_size -= save_size;
 596       png_ptr->current_buffer_ptr += save_size;
 597    }
 598 }
 599
 600 void /* PRIVATE */
 601 png_push_save_buffer(png_structp png_ptr)
 602 {
 603    if (png_ptr->save_buffer_size)
 604    {
 605       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
 606       {
 607          png_size_t i,istop;
 608          png_bytep sp;
 609          png_bytep dp;
 610
 611          istop = png_ptr->save_buffer_size;
 612          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
 613             i < istop; i++, sp++, dp++)
 614          {
 615             *dp = *sp;
 616          }
 617       }
 618    }
 619    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
 620       png_ptr->save_buffer_max)
 621    {
 622       png_size_t new_max;
 623       png_bytep old_buffer;
 624
 625       if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
 626          (png_ptr->current_buffer_size + 256))
 627       {
 628         png_error(png_ptr, "Potential overflow of save_buffer");
 629       }
 630       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
 631       old_buffer = png_ptr->save_buffer;
 632       png_ptr->save_buffer = (png_bytep)png_malloc(png_ptr,
 633          (png_uint_32)new_max);
 634       png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
 635       png_free(png_ptr, old_buffer);
 636       png_ptr->save_buffer_max = new_max;
 637    }
 638    if (png_ptr->current_buffer_size)
 639    {
 640       png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
 641          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
 642       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
 643       png_ptr->current_buffer_size = 0;
 644    }
 645    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
 646    png_ptr->buffer_size = 0;
 647 }
 648
 649 void /* PRIVATE */
 650 png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 651    png_size_t buffer_length)
 652 {
 653    png_ptr->current_buffer = buffer;
 654    png_ptr->current_buffer_size = buffer_length;
 655    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
 656    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 657 }
 658
 659 void /* PRIVATE */
 660 png_push_read_IDAT(png_structp png_ptr)
 661 {
 662 #ifdef PNG_USE_LOCAL_ARRAYS
 663    PNG_IDAT;
 664 #endif
 665    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
 666    {
 667       png_byte chunk_length[4];
 668
 669       if (png_ptr->buffer_size < 8)
 670       {
 671          png_push_save_buffer(png_ptr);
 672          return;
 673       }
 674
 675       png_push_fill_buffer(png_ptr, chunk_length, 4);
 676       png_ptr->push_length = png_get_uint_31(png_ptr,chunk_length);
 677       png_reset_crc(png_ptr);
 678       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
 679       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 680
 681       if (png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
 682       {
 683          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 684          if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 685             png_error(png_ptr, "Not enough compressed data");
 686          return;
 687       }
 688
 689       png_ptr->idat_size = png_ptr->push_length;
 690    }
 691    if (png_ptr->idat_size && png_ptr->save_buffer_size)
 692    {
 693       png_size_t save_size;
 694
 695       if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
 696       {
 697          save_size = (png_size_t)png_ptr->idat_size;
 698          /* check for overflow */
 699          if((png_uint_32)save_size != png_ptr->idat_size)
 700             png_error(png_ptr, "save_size overflowed in pngpread");
 701       }
 702       else
 703          save_size = png_ptr->save_buffer_size;
 704
 705       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 706       if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 707          png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 708       png_ptr->idat_size -= save_size;
 709       png_ptr->buffer_size -= save_size;
 710       png_ptr->save_buffer_size -= save_size;
 711       png_ptr->save_buffer_ptr += save_size;
 712    }
 713    if (png_ptr->idat_size && png_ptr->current_buffer_size)
 714    {
 715       png_size_t save_size;
 716
 717       if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
 718       {
 719          save_size = (png_size_t)png_ptr->idat_size;
 720          /* check for overflow */
 721          if((png_uint_32)save_size != png_ptr->idat_size)
 722             png_error(png_ptr, "save_size overflowed in pngpread");
 723       }
 724       else
 725          save_size = png_ptr->current_buffer_size;
 726
 727       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
 728       if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
 729         png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 730
 731       png_ptr->idat_size -= save_size;
 732       png_ptr->buffer_size -= save_size;
 733       png_ptr->current_buffer_size -= save_size;
 734       png_ptr->current_buffer_ptr += save_size;
 735    }
 736    if (!png_ptr->idat_size)
 737    {
 738       if (png_ptr->buffer_size < 4)
 739       {
 740          png_push_save_buffer(png_ptr);
 741          return;
 742       }
 743
 744       png_crc_finish(png_ptr, 0);
 745       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 746       png_ptr->mode |= PNG_AFTER_IDAT;
 747    }
 748 }
 749
 750 void /* PRIVATE */
 751 png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 752    png_size_t buffer_length)
 753 {
 754    int ret;
 755
 756    if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
 757       png_error(png_ptr, "Extra compression data");
 758
 759    png_ptr->zstream.next_in = buffer;
 760    png_ptr->zstream.avail_in = (uInt)buffer_length;
 761    for(;;)
 762    {
 763       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 764       if (ret != Z_OK)
 765       {
 766          if (ret == Z_STREAM_END)
 767          {
 768             if (png_ptr->zstream.avail_in)
 769                png_error(png_ptr, "Extra compressed data");
 770             if (!(png_ptr->zstream.avail_out))
 771             {
 772                png_push_process_row(png_ptr);
 773             }
 774
 775             png_ptr->mode |= PNG_AFTER_IDAT;
 776             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 777             break;
 778          }
 779          else if (ret == Z_BUF_ERROR)
 780             break;
 781          else
 782             png_error(png_ptr, "Decompression Error");
 783       }
 784       if (!(png_ptr->zstream.avail_out))
 785       {
 786          if ((
 787 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 788              png_ptr->interlaced && png_ptr->pass > 6) ||
 789              (!png_ptr->interlaced &&
 790 #endif
 791              png_ptr->row_number == png_ptr->num_rows))
 792          {
 793            if (png_ptr->zstream.avail_in)
 794              png_warning(png_ptr, "Too much data in IDAT chunks");
 795            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 796            break;
 797          }
 798          png_push_process_row(png_ptr);
 799          png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
 800          png_ptr->zstream.next_out = png_ptr->row_buf;
 801       }
 802       else
 803          break;
 804    }
 805 }
 806
 807 void /* PRIVATE */
 808 png_push_process_row(png_structp png_ptr)
 809 {
 810    png_ptr->row_info.color_type = png_ptr->color_type;
 811    png_ptr->row_info.width = png_ptr->iwidth;
 812    png_ptr->row_info.channels = png_ptr->channels;
 813    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
 814    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
 815
 816    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
 817        png_ptr->row_info.width);
 818
 819    png_read_filter_row(png_ptr, &(png_ptr->row_info),
 820       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
 821       (int)(png_ptr->row_buf[0]));
 822
 823    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
 824       png_ptr->rowbytes + 1);
 825
 826    if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
 827       png_do_read_transformations(png_ptr);
 828
 829 #if defined(PNG_READ_INTERLACING_SUPPORTED)
 830    /* blow up interlaced rows to full size */
 831    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 832    {
 833       if (png_ptr->pass < 6)
 834 /*       old interface (pre-1.0.9):
 835          png_do_read_interlace(&(png_ptr->row_info),
 836             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
 837  */
 838          png_do_read_interlace(png_ptr);
 839
 840     switch (png_ptr->pass)
 841     {
 842          case 0:
 843          {
 844             int i;
 845             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
 846             {
 847                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 848                png_read_push_finish_row(png_ptr); /* updates png_ptr->pass */
 849             }
 850             if (png_ptr->pass == 2) /* pass 1 might be empty */
 851             {
 852                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 853                {
 854                   png_push_have_row(png_ptr, png_bytep_NULL);
 855                   png_read_push_finish_row(png_ptr);
 856                }
 857             }
 858             if (png_ptr->pass == 4 && png_ptr->height <= 4)
 859             {
 860                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 861                {
 862                   png_push_have_row(png_ptr, png_bytep_NULL);
 863                   png_read_push_finish_row(png_ptr);
 864                }
 865             }
 866             if (png_ptr->pass == 6 && png_ptr->height <= 4)
 867             {
 868                 png_push_have_row(png_ptr, png_bytep_NULL);
 869                 png_read_push_finish_row(png_ptr);
 870             }
 871             break;
 872          }
 873          case 1:
 874          {
 875             int i;
 876             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
 877             {
 878                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 879                png_read_push_finish_row(png_ptr);
 880             }
 881             if (png_ptr->pass == 2) /* skip top 4 generated rows */
 882             {
 883                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 884                {
 885                   png_push_have_row(png_ptr, png_bytep_NULL);
 886                   png_read_push_finish_row(png_ptr);
 887                }
 888             }
 889             break;
 890          }
 891          case 2:
 892          {
 893             int i;
 894             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 895             {
 896                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 897                png_read_push_finish_row(png_ptr);
 898             }
 899             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
 900             {
 901                png_push_have_row(png_ptr, png_bytep_NULL);
 902                png_read_push_finish_row(png_ptr);
 903             }
 904             if (png_ptr->pass == 4) /* pass 3 might be empty */
 905             {
 906                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 907                {
 908                   png_push_have_row(png_ptr, png_bytep_NULL);
 909                   png_read_push_finish_row(png_ptr);
 910                }
 911             }
 912             break;
 913          }
 914          case 3:
 915          {
 916             int i;
 917             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
 918             {
 919                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 920                png_read_push_finish_row(png_ptr);
 921             }
 922             if (png_ptr->pass == 4) /* skip top two generated rows */
 923             {
 924                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 925                {
 926                   png_push_have_row(png_ptr, png_bytep_NULL);
 927                   png_read_push_finish_row(png_ptr);
 928                }
 929             }
 930             break;
 931          }
 932          case 4:
 933          {
 934             int i;
 935             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 936             {
 937                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 938                png_read_push_finish_row(png_ptr);
 939             }
 940             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
 941             {
 942                png_push_have_row(png_ptr, png_bytep_NULL);
 943                png_read_push_finish_row(png_ptr);
 944             }
 945             if (png_ptr->pass == 6) /* pass 5 might be empty */
 946             {
 947                png_push_have_row(png_ptr, png_bytep_NULL);
 948                png_read_push_finish_row(png_ptr);
 949             }
 950             break;
 951          }
 952          case 5:
 953          {
 954             int i;
 955             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
 956             {
 957                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 958                png_read_push_finish_row(png_ptr);
 959             }
 960             if (png_ptr->pass == 6) /* skip top generated row */
 961             {
 962                png_push_have_row(png_ptr, png_bytep_NULL);
 963                png_read_push_finish_row(png_ptr);
 964             }
 965             break;
 966          }
 967          case 6:
 968          {
 969             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 970             png_read_push_finish_row(png_ptr);
 971             if (png_ptr->pass != 6)
 972                break;
 973             png_push_have_row(png_ptr, png_bytep_NULL);
 974             png_read_push_finish_row(png_ptr);
 975          }
 976       }
 977    }
 978    else
 979 #endif
 980    {
 981       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
 982       png_read_push_finish_row(png_ptr);
 983    }
 984 }
 985
 986 void /* PRIVATE */
 987 png_read_push_finish_row(png_structp png_ptr)
 988 {
 989 #ifdef PNG_USE_LOCAL_ARRAYS
 990    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 991
 992    /* start of interlace block */
 993    const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 994
 995    /* offset to next interlace block */
 996    const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 997
 998    /* start of interlace block in the y direction */
 999    const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
1000
1001    /* offset to next interlace block in the y direction */
1002    const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
1003
1004    /* Width of interlace block.  This is not currently used - if you need
1005     * it, uncomment it here and in png.h
1006    const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
1007    */
1008
1009    /* Height of interlace block.  This is not currently used - if you need
1010     * it, uncomment it here and in png.h
1011    const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
1012    */
1013 #endif
1014
1015    png_ptr->row_number++;
1016    if (png_ptr->row_number < png_ptr->num_rows)
1017       return;
1018
1019    if (png_ptr->interlaced)
1020    {
1021       png_ptr->row_number = 0;
1022       png_memset_check(png_ptr, png_ptr->prev_row, 0,
1023          png_ptr->rowbytes + 1);
1024       do
1025       {
1026          png_ptr->pass++;
1027          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1028              (png_ptr->pass == 3 && png_ptr->width < 3) ||
1029              (png_ptr->pass == 5 && png_ptr->width < 2))
1030            png_ptr->pass++;
1031
1032          if (png_ptr->pass > 7)
1033             png_ptr->pass--;
1034          if (png_ptr->pass >= 7)
1035             break;
1036
1037          png_ptr->iwidth = (png_ptr->width +
1038             png_pass_inc[png_ptr->pass] - 1 -
1039             png_pass_start[png_ptr->pass]) /
1040             png_pass_inc[png_ptr->pass];
1041
1042          png_ptr->irowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,
1043             png_ptr->iwidth) + 1;
1044
1045          if (png_ptr->transformations & PNG_INTERLACE)
1046             break;
1047
1048          png_ptr->num_rows = (png_ptr->height +
1049             png_pass_yinc[png_ptr->pass] - 1 -
1050             png_pass_ystart[png_ptr->pass]) /
1051             png_pass_yinc[png_ptr->pass];
1052
1053       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1054    }
1055 }
1056
1057 #if defined(PNG_READ_tEXt_SUPPORTED)
1058 void /* PRIVATE */
1059 png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1060    length)
1061 {
1062    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1063       {
1064          png_error(png_ptr, "Out of place tEXt");
1065          /* to quiet some compiler warnings */
1066          if(info_ptr == NULL) return;
1067       }
1068
1069 #ifdef PNG_MAX_MALLOC_64K
1070    png_ptr->skip_length = 0;  /* This may not be necessary */
1071
1072    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
1073    {
1074       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
1075       png_ptr->skip_length = length - (png_uint_32)65535L;
1076       length = (png_uint_32)65535L;
1077    }
1078 #endif
1079
1080    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1081          (png_uint_32)(length+1));
1082    png_ptr->current_text[length] = '\0';
1083    png_ptr->current_text_ptr = png_ptr->current_text;
1084    png_ptr->current_text_size = (png_size_t)length;
1085    png_ptr->current_text_left = (png_size_t)length;
1086    png_ptr->process_mode = PNG_READ_tEXt_MODE;
1087 }
1088
1089 void /* PRIVATE */
1090 png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
1091 {
1092    if (png_ptr->buffer_size && png_ptr->current_text_left)
1093    {
1094       png_size_t text_size;
1095
1096       if (png_ptr->buffer_size < png_ptr->current_text_left)
1097          text_size = png_ptr->buffer_size;
1098       else
1099          text_size = png_ptr->current_text_left;
1100       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1101       png_ptr->current_text_left -= text_size;
1102       png_ptr->current_text_ptr += text_size;
1103    }
1104    if (!(png_ptr->current_text_left))
1105    {
1106       png_textp text_ptr;
1107       png_charp text;
1108       png_charp key;
1109       int ret;
1110
1111       if (png_ptr->buffer_size < 4)
1112       {
1113          png_push_save_buffer(png_ptr);
1114          return;
1115       }
1116
1117       png_push_crc_finish(png_ptr);
1118
1119 #if defined(PNG_MAX_MALLOC_64K)
1120       if (png_ptr->skip_length)
1121          return;
1122 #endif
1123
1124       key = png_ptr->current_text;
1125
1126       for (text = key; *text; text++)
1127          /* empty loop */ ;
1128
1129       if (text != key + png_ptr->current_text_size)
1130          text++;
1131
1132       text_ptr = (png_textp)png_malloc(png_ptr,
1133          (png_uint_32)png_sizeof(png_text));
1134       text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
1135       text_ptr->key = key;
1136 #ifdef PNG_iTXt_SUPPORTED
1137       text_ptr->lang = NULL;
1138       text_ptr->lang_key = NULL;
1139 #endif
1140       text_ptr->text = text;
1141
1142       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1143
1144       png_free(png_ptr, key);
1145       png_free(png_ptr, text_ptr);
1146       png_ptr->current_text = NULL;
1147
1148       if (ret)
1149         png_warning(png_ptr, "Insufficient memory to store text chunk.");
1150    }
1151 }
1152 #endif
1153
1154 #if defined(PNG_READ_zTXt_SUPPORTED)
1155 void /* PRIVATE */
1156 png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1157    length)
1158 {
1159    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1160       {
1161          png_error(png_ptr, "Out of place zTXt");
1162          /* to quiet some compiler warnings */
1163          if(info_ptr == NULL) return;
1164       }
1165
1166 #ifdef PNG_MAX_MALLOC_64K
1167    /* We can't handle zTXt chunks > 64K, since we don't have enough space
1168     * to be able to store the uncompressed data.  Actually, the threshold
1169     * is probably around 32K, but it isn't as definite as 64K is.
1170     */
1171    if (length > (png_uint_32)65535L)
1172    {
1173       png_warning(png_ptr, "zTXt chunk too large to fit in memory");
1174       png_push_crc_skip(png_ptr, length);
1175       return;
1176    }
1177 #endif
1178
1179    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1180        (png_uint_32)(length+1));
1181    png_ptr->current_text[length] = '\0';
1182    png_ptr->current_text_ptr = png_ptr->current_text;
1183    png_ptr->current_text_size = (png_size_t)length;
1184    png_ptr->current_text_left = (png_size_t)length;
1185    png_ptr->process_mode = PNG_READ_zTXt_MODE;
1186 }
1187
1188 void /* PRIVATE */
1189 png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
1190 {
1191    if (png_ptr->buffer_size && png_ptr->current_text_left)
1192    {
1193       png_size_t text_size;
1194
1195       if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left)
1196          text_size = png_ptr->buffer_size;
1197       else
1198          text_size = png_ptr->current_text_left;
1199       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1200       png_ptr->current_text_left -= text_size;
1201       png_ptr->current_text_ptr += text_size;
1202    }
1203    if (!(png_ptr->current_text_left))
1204    {
1205       png_textp text_ptr;
1206       png_charp text;
1207       png_charp key;
1208       int ret;
1209       png_size_t text_size, key_size;
1210
1211       if (png_ptr->buffer_size < 4)
1212       {
1213          png_push_save_buffer(png_ptr);
1214          return;
1215       }
1216
1217       png_push_crc_finish(png_ptr);
1218
1219       key = png_ptr->current_text;
1220
1221       for (text = key; *text; text++)
1222          /* empty loop */ ;
1223
1224       /* zTXt can't have zero text */
1225       if (text == key + png_ptr->current_text_size)
1226       {
1227          png_ptr->current_text = NULL;
1228          png_free(png_ptr, key);
1229          return;
1230       }
1231
1232       text++;
1233
1234       if (*text != PNG_TEXT_COMPRESSION_zTXt) /* check compression byte */
1235       {
1236          png_ptr->current_text = NULL;
1237          png_free(png_ptr, key);
1238          return;
1239       }
1240
1241       text++;
1242
1243       png_ptr->zstream.next_in = (png_bytep )text;
1244       png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size -
1245          (text - key));
1246       png_ptr->zstream.next_out = png_ptr->zbuf;
1247       png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1248
1249       key_size = text - key;
1250       text_size = 0;
1251       text = NULL;
1252       ret = Z_STREAM_END;
1253
1254       while (png_ptr->zstream.avail_in)
1255       {
1256          ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
1257          if (ret != Z_OK && ret != Z_STREAM_END)
1258          {
1259             inflateReset(&png_ptr->zstream);
1260             png_ptr->zstream.avail_in = 0;
1261             png_ptr->current_text = NULL;
1262             png_free(png_ptr, key);
1263             png_free(png_ptr, text);
1264             return;
1265          }
1266          if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END)
1267          {
1268             if (text == NULL)
1269             {
1270                text = (png_charp)png_malloc(png_ptr,
1271                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out
1272                      + key_size + 1));
1273                png_memcpy(text + key_size, png_ptr->zbuf,
1274                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1275                png_memcpy(text, key, key_size);
1276                text_size = key_size + png_ptr->zbuf_size -
1277                   png_ptr->zstream.avail_out;
1278                *(text + text_size) = '\0';
1279             }
1280             else
1281             {
1282                png_charp tmp;
1283
1284                tmp = text;
1285                text = (png_charp)png_malloc(png_ptr, text_size +
1286                   (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out
1287                    + 1));
1288                png_memcpy(text, tmp, text_size);
1289                png_free(png_ptr, tmp);
1290                png_memcpy(text + text_size, png_ptr->zbuf,
1291                   png_ptr->zbuf_size - png_ptr->zstream.avail_out);
1292                text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
1293                *(text + text_size) = '\0';
1294             }
1295             if (ret != Z_STREAM_END)
1296             {
1297                png_ptr->zstream.next_out = png_ptr->zbuf;
1298                png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1299             }
1300          }
1301          else
1302          {
1303             break;
1304          }
1305
1306          if (ret == Z_STREAM_END)
1307             break;
1308       }
1309
1310       inflateReset(&png_ptr->zstream);
1311       png_ptr->zstream.avail_in = 0;
1312
1313       if (ret != Z_STREAM_END)
1314       {
1315          png_ptr->current_text = NULL;
1316          png_free(png_ptr, key);
1317          png_free(png_ptr, text);
1318          return;
1319       }
1320
1321       png_ptr->current_text = NULL;
1322       png_free(png_ptr, key);
1323       key = text;
1324       text += key_size;
1325
1326       text_ptr = (png_textp)png_malloc(png_ptr,
1327           (png_uint_32)png_sizeof(png_text));
1328       text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt;
1329       text_ptr->key = key;
1330 #ifdef PNG_iTXt_SUPPORTED
1331       text_ptr->lang = NULL;
1332       text_ptr->lang_key = NULL;
1333 #endif
1334       text_ptr->text = text;
1335
1336       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1337
1338       png_free(png_ptr, key);
1339       png_free(png_ptr, text_ptr);
1340
1341       if (ret)
1342         png_warning(png_ptr, "Insufficient memory to store text chunk.");
1343    }
1344 }
1345 #endif
1346
1347 #if defined(PNG_READ_iTXt_SUPPORTED)
1348 void /* PRIVATE */
1349 png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
1350    length)
1351 {
1352    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
1353       {
1354          png_error(png_ptr, "Out of place iTXt");
1355          /* to quiet some compiler warnings */
1356          if(info_ptr == NULL) return;
1357       }
1358
1359 #ifdef PNG_MAX_MALLOC_64K
1360    png_ptr->skip_length = 0;  /* This may not be necessary */
1361
1362    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
1363    {
1364       png_warning(png_ptr, "iTXt chunk too large to fit in memory");
1365       png_ptr->skip_length = length - (png_uint_32)65535L;
1366       length = (png_uint_32)65535L;
1367    }
1368 #endif
1369
1370    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
1371          (png_uint_32)(length+1));
1372    png_ptr->current_text[length] = '\0';
1373    png_ptr->current_text_ptr = png_ptr->current_text;
1374    png_ptr->current_text_size = (png_size_t)length;
1375    png_ptr->current_text_left = (png_size_t)length;
1376    png_ptr->process_mode = PNG_READ_iTXt_MODE;
1377 }
1378
1379 void /* PRIVATE */
1380 png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr)
1381 {
1382
1383    if (png_ptr->buffer_size && png_ptr->current_text_left)
1384    {
1385       png_size_t text_size;
1386
1387       if (png_ptr->buffer_size < png_ptr->current_text_left)
1388          text_size = png_ptr->buffer_size;
1389       else
1390          text_size = png_ptr->current_text_left;
1391       png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
1392       png_ptr->current_text_left -= text_size;
1393       png_ptr->current_text_ptr += text_size;
1394    }
1395    if (!(png_ptr->current_text_left))
1396    {
1397       png_textp text_ptr;
1398       png_charp key;
1399       int comp_flag;
1400       png_charp lang;
1401       png_charp lang_key;
1402       png_charp text;
1403       int ret;
1404
1405       if (png_ptr->buffer_size < 4)
1406       {
1407          png_push_save_buffer(png_ptr);
1408          return;
1409       }
1410
1411       png_push_crc_finish(png_ptr);
1412
1413 #if defined(PNG_MAX_MALLOC_64K)
1414       if (png_ptr->skip_length)
1415          return;
1416 #endif
1417
1418       key = png_ptr->current_text;
1419
1420       for (lang = key; *lang; lang++)
1421          /* empty loop */ ;
1422
1423       if (lang != key + png_ptr->current_text_size)
1424          lang++;
1425
1426       comp_flag = *lang++;
1427       lang++;     /* skip comp_type, always zero */
1428
1429       for (lang_key = lang; *lang_key; lang_key++)
1430          /* empty loop */ ;
1431       lang_key++;        /* skip NUL separator */
1432
1433       for (text = lang_key; *text; text++)
1434          /* empty loop */ ;
1435
1436       if (text != key + png_ptr->current_text_size)
1437          text++;
1438
1439       text_ptr = (png_textp)png_malloc(png_ptr,
1440          (png_uint_32)png_sizeof(png_text));
1441       text_ptr->compression = comp_flag + 2;
1442       text_ptr->key = key;
1443       text_ptr->lang = lang;
1444       text_ptr->lang_key = lang_key;
1445       text_ptr->text = text;
1446       text_ptr->text_length = 0;
1447       text_ptr->itxt_length = png_strlen(text);
1448
1449       ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
1450
1451       png_ptr->current_text = NULL;
1452
1453       png_free(png_ptr, text_ptr);
1454       if (ret)
1455         png_warning(png_ptr, "Insufficient memory to store iTXt chunk.");
1456    }
1457 }
1458 #endif
1459
1460 /* This function is called when we haven't found a handler for this
1461  * chunk.  If there isn't a problem with the chunk itself (ie a bad chunk
1462  * name or a critical chunk), the chunk is (currently) silently ignored.
1463  */
1464 void /* PRIVATE */
1465 png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
1466    length)
1467 {
1468    png_uint_32 skip=0;
1469    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
1470
1471    if (!(png_ptr->chunk_name[0] & 0x20))
1472    {
1473 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1474       if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1475            PNG_HANDLE_CHUNK_ALWAYS
1476 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
1477            && png_ptr->read_user_chunk_fn == NULL
1478 #endif
1479          )
1480 #endif
1481          png_chunk_error(png_ptr, "unknown critical chunk");
1482
1483       /* to quiet compiler warnings about unused info_ptr */
1484       if (info_ptr == NULL)
1485          return;
1486    }
1487
1488 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1489    if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
1490    {
1491 #ifdef PNG_MAX_MALLOC_64K
1492        if (length > (png_uint_32)65535L)
1493        {
1494            png_warning(png_ptr, "unknown chunk too large to fit in memory");
1495            skip = length - (png_uint_32)65535L;
1496            length = (png_uint_32)65535L;
1497        }
1498 #endif
1499        png_strcpy((png_charp)png_ptr->unknown_chunk.name,
1500          (png_charp)png_ptr->chunk_name);
1501        png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
1502        png_ptr->unknown_chunk.size = (png_size_t)length;
1503        png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
1504 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
1505        if(png_ptr->read_user_chunk_fn != NULL)
1506        {
1507           /* callback to user unknown chunk handler */
1508           int ret;
1509           ret = (*(png_ptr->read_user_chunk_fn))
1510             (png_ptr, &png_ptr->unknown_chunk);
1511           if (ret < 0)
1512              png_chunk_error(png_ptr, "error in user chunk");
1513           if (ret == 0)
1514           {
1515              if (!(png_ptr->chunk_name[0] & 0x20))
1516                 if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
1517                      PNG_HANDLE_CHUNK_ALWAYS)
1518                    png_chunk_error(png_ptr, "unknown critical chunk");
1519                 png_set_unknown_chunks(png_ptr, info_ptr,
1520                    &png_ptr->unknown_chunk, 1);
1521           }
1522        }
1523 #else
1524        png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
1525 #endif
1526        png_free(png_ptr, png_ptr->unknown_chunk.data);
1527        png_ptr->unknown_chunk.data = NULL;
1528    }
1529    else
1530 #endif
1531       skip=length;
1532    png_push_crc_skip(png_ptr, skip);
1533 }
1534
1535 void /* PRIVATE */
1536 png_push_have_info(png_structp png_ptr, png_infop info_ptr)
1537 {
1538    if (png_ptr->info_fn != NULL)
1539       (*(png_ptr->info_fn))(png_ptr, info_ptr);
1540 }
1541
1542 void /* PRIVATE */
1543 png_push_have_end(png_structp png_ptr, png_infop info_ptr)
1544 {
1545    if (png_ptr->end_fn != NULL)
1546       (*(png_ptr->end_fn))(png_ptr, info_ptr);
1547 }
1548
1549 void /* PRIVATE */
1550 png_push_have_row(png_structp png_ptr, png_bytep row)
1551 {
1552    if (png_ptr->row_fn != NULL)
1553       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1554          (int)png_ptr->pass);
1555 }
1556
1557 void PNGAPI
1558 png_progressive_combine_row (png_structp png_ptr,
1559    png_bytep old_row, png_bytep new_row)
1560 {
1561 #ifdef PNG_USE_LOCAL_ARRAYS
1562    const int FARDATA png_pass_dsp_mask[7] =
1563       {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
1564 #endif
1565    if(png_ptr == NULL) return;
1566    if (new_row != NULL)    /* new_row must == png_ptr->row_buf here. */
1567       png_combine_row(png_ptr, old_row, png_pass_dsp_mask[png_ptr->pass]);
1568 }
1569
1570 void PNGAPI
1571 png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
1572    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1573    png_progressive_end_ptr end_fn)
1574 {
1575    if(png_ptr == NULL) return;
1576    png_ptr->info_fn = info_fn;
1577    png_ptr->row_fn = row_fn;
1578    png_ptr->end_fn = end_fn;
1579
1580    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1581 }
1582
1583 png_voidp PNGAPI
1584 png_get_progressive_ptr(png_structp png_ptr)
1585 {
1586    if(png_ptr == NULL) return (NULL);
1587    return png_ptr->io_ptr;
1588 }
1589 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */