1 2 /* pngpread.c - read a png file in push mode 3 * 4 * Last changed in libpng 1.6.18 [July 23, 2015] 5 * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson 6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 8 * 9 * This code is released under the libpng license. 10 * For conditions of distribution and use, see the disclaimer 11 * and license in png.h 12 */ 13 14 #include "pngpriv.h" 15 16 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED 17 18 /* Push model modes */ 19 #define PNG_READ_SIG_MODE 0 20 #define PNG_READ_CHUNK_MODE 1 21 #define PNG_READ_IDAT_MODE 2 22 #define PNG_READ_tEXt_MODE 4 23 #define PNG_READ_zTXt_MODE 5 24 #define PNG_READ_DONE_MODE 6 25 #define PNG_READ_iTXt_MODE 7 26 #define PNG_ERROR_MODE 8 27 28 #define PNG_PUSH_SAVE_BUFFER_IF_FULL \ 29 if (png_ptr->push_length + 4 > png_ptr->buffer_size) \ 30 { png_push_save_buffer(png_ptr); return; } 31 #define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \ 32 if (png_ptr->buffer_size < N) \ 33 { png_push_save_buffer(png_ptr); return; } 34 35 void PNGAPI 36 png_process_data(png_structrp png_ptr, png_inforp info_ptr, 37 png_bytep buffer, png_size_t buffer_size) 38 { 39 if (png_ptr == NULL || info_ptr == NULL) 40 return; 41 42 png_push_restore_buffer(png_ptr, buffer, buffer_size); 43 44 while (png_ptr->buffer_size) 45 { 46 png_process_some_data(png_ptr, info_ptr); 47 } 48 } 49 50 png_size_t PNGAPI 51 png_process_data_pause(png_structrp png_ptr, int save) 52 { 53 if (png_ptr != NULL) 54 { 55 /* It's easiest for the caller if we do the save; then the caller doesn't 56 * have to supply the same data again: 57 */ 58 if (save != 0) 59 png_push_save_buffer(png_ptr); 60 else 61 { 62 /* This includes any pending saved bytes: */ 63 png_size_t remaining = png_ptr->buffer_size; 64 png_ptr->buffer_size = 0; 65 66 /* So subtract the saved buffer size, unless all the data 67 * is actually 'saved', in which case we just return 0 68 */ 69 if (png_ptr->save_buffer_size < remaining) 70 return remaining - png_ptr->save_buffer_size; 71 } 72 } 73 74 return 0; 75 } 76 77 png_uint_32 PNGAPI 78 png_process_data_skip(png_structrp png_ptr) 79 { 80 /* TODO: Deprecate and remove this API. 81 * Somewhere the implementation of this seems to have been lost, 82 * or abandoned. It was only to support some internal back-door access 83 * to png_struct) in libpng-1.4.x. 84 */ 85 png_app_warning(png_ptr, 86 "png_process_data_skip is not implemented in any current version of libpng"); 87 return 0; 88 } 89 90 /* What we do with the incoming data depends on what we were previously 91 * doing before we ran out of data... 92 */ 93 void /* PRIVATE */ 94 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr) 95 { 96 if (png_ptr == NULL) 97 return; 98 99 switch (png_ptr->process_mode) 100 { 101 case PNG_READ_SIG_MODE: 102 { 103 png_push_read_sig(png_ptr, info_ptr); 104 break; 105 } 106 107 case PNG_READ_CHUNK_MODE: 108 { 109 png_push_read_chunk(png_ptr, info_ptr); 110 break; 111 } 112 113 case PNG_READ_IDAT_MODE: 114 { 115 png_push_read_IDAT(png_ptr); 116 break; 117 } 118 119 default: 120 { 121 png_ptr->buffer_size = 0; 122 break; 123 } 124 } 125 } 126 127 /* Read any remaining signature bytes from the stream and compare them with 128 * the correct PNG signature. It is possible that this routine is called 129 * with bytes already read from the signature, either because they have been 130 * checked by the calling application, or because of multiple calls to this 131 * routine. 132 */ 133 void /* PRIVATE */ 134 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr) 135 { 136 png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */ 137 num_to_check = 8 - num_checked; 138 139 if (png_ptr->buffer_size < num_to_check) 140 { 141 num_to_check = png_ptr->buffer_size; 142 } 143 144 png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]), 145 num_to_check); 146 png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check); 147 148 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check)) 149 { 150 if (num_checked < 4 && 151 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4)) 152 png_error(png_ptr, "Not a PNG file"); 153 154 else 155 png_error(png_ptr, "PNG file corrupted by ASCII conversion"); 156 } 157 else 158 { 159 if (png_ptr->sig_bytes >= 8) 160 { 161 png_ptr->process_mode = PNG_READ_CHUNK_MODE; 162 } 163 } 164 } 165 166 void /* PRIVATE */ 167 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr) 168 { 169 png_uint_32 chunk_name; 170 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 171 int keep; /* unknown handling method */ 172 #endif 173 174 /* First we make sure we have enough data for the 4-byte chunk name 175 * and the 4-byte chunk length before proceeding with decoding the 176 * chunk data. To fully decode each of these chunks, we also make 177 * sure we have enough data in the buffer for the 4-byte CRC at the 178 * end of every chunk (except IDAT, which is handled separately). 179 */ 180 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0) 181 { 182 png_byte chunk_length[4]; 183 png_byte chunk_tag[4]; 184 185 PNG_PUSH_SAVE_BUFFER_IF_LT(8) 186 png_push_fill_buffer(png_ptr, chunk_length, 4); 187 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length); 188 png_reset_crc(png_ptr); 189 png_crc_read(png_ptr, chunk_tag, 4); 190 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag); 191 png_check_chunk_name(png_ptr, png_ptr->chunk_name); 192 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER; 193 } 194 195 chunk_name = png_ptr->chunk_name; 196 197 if (chunk_name == png_IDAT) 198 { 199 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) 200 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; 201 202 /* If we reach an IDAT chunk, this means we have read all of the 203 * header chunks, and we can start reading the image (or if this 204 * is called after the image has been read - we have an error). 205 */ 206 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) 207 png_error(png_ptr, "Missing IHDR before IDAT"); 208 209 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && 210 (png_ptr->mode & PNG_HAVE_PLTE) == 0) 211 png_error(png_ptr, "Missing PLTE before IDAT"); 212 213 png_ptr->process_mode = PNG_READ_IDAT_MODE; 214 215 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) 216 if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0) 217 if (png_ptr->push_length == 0) 218 return; 219 220 png_ptr->mode |= PNG_HAVE_IDAT; 221 222 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) 223 png_benign_error(png_ptr, "Too many IDATs found"); 224 } 225 226 if (chunk_name == png_IHDR) 227 { 228 if (png_ptr->push_length != 13) 229 png_error(png_ptr, "Invalid IHDR length"); 230 231 PNG_PUSH_SAVE_BUFFER_IF_FULL 232 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length); 233 } 234 235 else if (chunk_name == png_IEND) 236 { 237 PNG_PUSH_SAVE_BUFFER_IF_FULL 238 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length); 239 240 png_ptr->process_mode = PNG_READ_DONE_MODE; 241 png_push_have_end(png_ptr, info_ptr); 242 } 243 244 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 245 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) 246 { 247 PNG_PUSH_SAVE_BUFFER_IF_FULL 248 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep); 249 250 if (chunk_name == png_PLTE) 251 png_ptr->mode |= PNG_HAVE_PLTE; 252 } 253 #endif 254 255 else if (chunk_name == png_PLTE) 256 { 257 PNG_PUSH_SAVE_BUFFER_IF_FULL 258 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length); 259 } 260 261 else if (chunk_name == png_IDAT) 262 { 263 png_ptr->idat_size = png_ptr->push_length; 264 png_ptr->process_mode = PNG_READ_IDAT_MODE; 265 png_push_have_info(png_ptr, info_ptr); 266 png_ptr->zstream.avail_out = 267 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth, 268 png_ptr->iwidth) + 1; 269 png_ptr->zstream.next_out = png_ptr->row_buf; 270 return; 271 } 272 273 #ifdef PNG_READ_gAMA_SUPPORTED 274 else if (png_ptr->chunk_name == png_gAMA) 275 { 276 PNG_PUSH_SAVE_BUFFER_IF_FULL 277 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length); 278 } 279 280 #endif 281 #ifdef PNG_READ_sBIT_SUPPORTED 282 else if (png_ptr->chunk_name == png_sBIT) 283 { 284 PNG_PUSH_SAVE_BUFFER_IF_FULL 285 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length); 286 } 287 288 #endif 289 #ifdef PNG_READ_cHRM_SUPPORTED 290 else if (png_ptr->chunk_name == png_cHRM) 291 { 292 PNG_PUSH_SAVE_BUFFER_IF_FULL 293 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length); 294 } 295 296 #endif 297 #ifdef PNG_READ_sRGB_SUPPORTED 298 else if (chunk_name == png_sRGB) 299 { 300 PNG_PUSH_SAVE_BUFFER_IF_FULL 301 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length); 302 } 303 304 #endif 305 #ifdef PNG_READ_iCCP_SUPPORTED 306 else if (png_ptr->chunk_name == png_iCCP) 307 { 308 PNG_PUSH_SAVE_BUFFER_IF_FULL 309 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length); 310 } 311 312 #endif 313 #ifdef PNG_READ_sPLT_SUPPORTED 314 else if (chunk_name == png_sPLT) 315 { 316 PNG_PUSH_SAVE_BUFFER_IF_FULL 317 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length); 318 } 319 320 #endif 321 #ifdef PNG_READ_tRNS_SUPPORTED 322 else if (chunk_name == png_tRNS) 323 { 324 PNG_PUSH_SAVE_BUFFER_IF_FULL 325 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length); 326 } 327 328 #endif 329 #ifdef PNG_READ_bKGD_SUPPORTED 330 else if (chunk_name == png_bKGD) 331 { 332 PNG_PUSH_SAVE_BUFFER_IF_FULL 333 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length); 334 } 335 336 #endif 337 #ifdef PNG_READ_hIST_SUPPORTED 338 else if (chunk_name == png_hIST) 339 { 340 PNG_PUSH_SAVE_BUFFER_IF_FULL 341 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length); 342 } 343 344 #endif 345 #ifdef PNG_READ_pHYs_SUPPORTED 346 else if (chunk_name == png_pHYs) 347 { 348 PNG_PUSH_SAVE_BUFFER_IF_FULL 349 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length); 350 } 351 352 #endif 353 #ifdef PNG_READ_oFFs_SUPPORTED 354 else if (chunk_name == png_oFFs) 355 { 356 PNG_PUSH_SAVE_BUFFER_IF_FULL 357 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length); 358 } 359 #endif 360 361 #ifdef PNG_READ_pCAL_SUPPORTED 362 else if (chunk_name == png_pCAL) 363 { 364 PNG_PUSH_SAVE_BUFFER_IF_FULL 365 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length); 366 } 367 368 #endif 369 #ifdef PNG_READ_sCAL_SUPPORTED 370 else if (chunk_name == png_sCAL) 371 { 372 PNG_PUSH_SAVE_BUFFER_IF_FULL 373 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length); 374 } 375 376 #endif 377 #ifdef PNG_READ_tIME_SUPPORTED 378 else if (chunk_name == png_tIME) 379 { 380 PNG_PUSH_SAVE_BUFFER_IF_FULL 381 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length); 382 } 383 384 #endif 385 #ifdef PNG_READ_tEXt_SUPPORTED 386 else if (chunk_name == png_tEXt) 387 { 388 PNG_PUSH_SAVE_BUFFER_IF_FULL 389 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length); 390 } 391 392 #endif 393 #ifdef PNG_READ_zTXt_SUPPORTED 394 else if (chunk_name == png_zTXt) 395 { 396 PNG_PUSH_SAVE_BUFFER_IF_FULL 397 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length); 398 } 399 400 #endif 401 #ifdef PNG_READ_iTXt_SUPPORTED 402 else if (chunk_name == png_iTXt) 403 { 404 PNG_PUSH_SAVE_BUFFER_IF_FULL 405 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length); 406 } 407 #endif 408 409 else 410 { 411 PNG_PUSH_SAVE_BUFFER_IF_FULL 412 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, 413 PNG_HANDLE_CHUNK_AS_DEFAULT); 414 } 415 416 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER; 417 } 418 419 void PNGCBAPI 420 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length) 421 { 422 png_bytep ptr; 423 424 if (png_ptr == NULL) 425 return; 426 427 ptr = buffer; 428 if (png_ptr->save_buffer_size != 0) 429 { 430 png_size_t save_size; 431 432 if (length < png_ptr->save_buffer_size) 433 save_size = length; 434 435 else 436 save_size = png_ptr->save_buffer_size; 437 438 memcpy(ptr, png_ptr->save_buffer_ptr, save_size); 439 length -= save_size; 440 ptr += save_size; 441 png_ptr->buffer_size -= save_size; 442 png_ptr->save_buffer_size -= save_size; 443 png_ptr->save_buffer_ptr += save_size; 444 } 445 if (length != 0 && png_ptr->current_buffer_size != 0) 446 { 447 png_size_t save_size; 448 449 if (length < png_ptr->current_buffer_size) 450 save_size = length; 451 452 else 453 save_size = png_ptr->current_buffer_size; 454 455 memcpy(ptr, png_ptr->current_buffer_ptr, save_size); 456 png_ptr->buffer_size -= save_size; 457 png_ptr->current_buffer_size -= save_size; 458 png_ptr->current_buffer_ptr += save_size; 459 } 460 } 461 462 void /* PRIVATE */ 463 png_push_save_buffer(png_structrp png_ptr) 464 { 465 if (png_ptr->save_buffer_size != 0) 466 { 467 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer) 468 { 469 png_size_t i, istop; 470 png_bytep sp; 471 png_bytep dp; 472 473 istop = png_ptr->save_buffer_size; 474 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer; 475 i < istop; i++, sp++, dp++) 476 { 477 *dp = *sp; 478 } 479 } 480 } 481 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size > 482 png_ptr->save_buffer_max) 483 { 484 png_size_t new_max; 485 png_bytep old_buffer; 486 487 if (png_ptr->save_buffer_size > PNG_SIZE_MAX - 488 (png_ptr->current_buffer_size + 256)) 489 { 490 png_error(png_ptr, "Potential overflow of save_buffer"); 491 } 492 493 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256; 494 old_buffer = png_ptr->save_buffer; 495 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr, 496 (png_size_t)new_max); 497 498 if (png_ptr->save_buffer == NULL) 499 { 500 png_free(png_ptr, old_buffer); 501 png_error(png_ptr, "Insufficient memory for save_buffer"); 502 } 503 504 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size); 505 png_free(png_ptr, old_buffer); 506 png_ptr->save_buffer_max = new_max; 507 } 508 if (png_ptr->current_buffer_size) 509 { 510 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size, 511 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size); 512 png_ptr->save_buffer_size += png_ptr->current_buffer_size; 513 png_ptr->current_buffer_size = 0; 514 } 515 png_ptr->save_buffer_ptr = png_ptr->save_buffer; 516 png_ptr->buffer_size = 0; 517 } 518 519 void /* PRIVATE */ 520 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer, 521 png_size_t buffer_length) 522 { 523 png_ptr->current_buffer = buffer; 524 png_ptr->current_buffer_size = buffer_length; 525 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size; 526 png_ptr->current_buffer_ptr = png_ptr->current_buffer; 527 } 528 529 void /* PRIVATE */ 530 png_push_read_IDAT(png_structrp png_ptr) 531 { 532 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0) 533 { 534 png_byte chunk_length[4]; 535 png_byte chunk_tag[4]; 536 537 /* TODO: this code can be commoned up with the same code in push_read */ 538 PNG_PUSH_SAVE_BUFFER_IF_LT(8) 539 png_push_fill_buffer(png_ptr, chunk_length, 4); 540 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length); 541 png_reset_crc(png_ptr); 542 png_crc_read(png_ptr, chunk_tag, 4); 543 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag); 544 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER; 545 546 if (png_ptr->chunk_name != png_IDAT) 547 { 548 png_ptr->process_mode = PNG_READ_CHUNK_MODE; 549 550 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0) 551 png_error(png_ptr, "Not enough compressed data"); 552 553 return; 554 } 555 556 png_ptr->idat_size = png_ptr->push_length; 557 } 558 559 if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0) 560 { 561 png_size_t save_size = png_ptr->save_buffer_size; 562 png_uint_32 idat_size = png_ptr->idat_size; 563 564 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they 565 * are of different types and we don't know which variable has the fewest 566 * bits. Carefully select the smaller and cast it to the type of the 567 * larger - this cannot overflow. Do not cast in the following test - it 568 * will break on either 16-bit or 64-bit platforms. 569 */ 570 if (idat_size < save_size) 571 save_size = (png_size_t)idat_size; 572 573 else 574 idat_size = (png_uint_32)save_size; 575 576 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size); 577 578 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size); 579 580 png_ptr->idat_size -= idat_size; 581 png_ptr->buffer_size -= save_size; 582 png_ptr->save_buffer_size -= save_size; 583 png_ptr->save_buffer_ptr += save_size; 584 } 585 586 if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0) 587 { 588 png_size_t save_size = png_ptr->current_buffer_size; 589 png_uint_32 idat_size = png_ptr->idat_size; 590 591 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they 592 * are of different types and we don't know which variable has the fewest 593 * bits. Carefully select the smaller and cast it to the type of the 594 * larger - this cannot overflow. 595 */ 596 if (idat_size < save_size) 597 save_size = (png_size_t)idat_size; 598 599 else 600 idat_size = (png_uint_32)save_size; 601 602 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size); 603 604 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size); 605 606 png_ptr->idat_size -= idat_size; 607 png_ptr->buffer_size -= save_size; 608 png_ptr->current_buffer_size -= save_size; 609 png_ptr->current_buffer_ptr += save_size; 610 } 611 612 if (png_ptr->idat_size == 0) 613 { 614 PNG_PUSH_SAVE_BUFFER_IF_LT(4) 615 png_crc_finish(png_ptr, 0); 616 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER; 617 png_ptr->mode |= PNG_AFTER_IDAT; 618 png_ptr->zowner = 0; 619 } 620 } 621 622 void /* PRIVATE */ 623 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer, 624 png_size_t buffer_length) 625 { 626 /* The caller checks for a non-zero buffer length. */ 627 if (!(buffer_length > 0) || buffer == NULL) 628 png_error(png_ptr, "No IDAT data (internal error)"); 629 630 /* This routine must process all the data it has been given 631 * before returning, calling the row callback as required to 632 * handle the uncompressed results. 633 */ 634 png_ptr->zstream.next_in = buffer; 635 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */ 636 png_ptr->zstream.avail_in = (uInt)buffer_length; 637 638 /* Keep going until the decompressed data is all processed 639 * or the stream marked as finished. 640 */ 641 while (png_ptr->zstream.avail_in > 0 && 642 (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0) 643 { 644 int ret; 645 646 /* We have data for zlib, but we must check that zlib 647 * has someplace to put the results. It doesn't matter 648 * if we don't expect any results -- it may be the input 649 * data is just the LZ end code. 650 */ 651 if (!(png_ptr->zstream.avail_out > 0)) 652 { 653 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */ 654 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth, 655 png_ptr->iwidth) + 1); 656 657 png_ptr->zstream.next_out = png_ptr->row_buf; 658 } 659 660 /* Using Z_SYNC_FLUSH here means that an unterminated 661 * LZ stream (a stream with a missing end code) can still 662 * be handled, otherwise (Z_NO_FLUSH) a future zlib 663 * implementation might defer output and therefore 664 * change the current behavior (see comments in inflate.c 665 * for why this doesn't happen at present with zlib 1.2.5). 666 */ 667 ret = PNG_INFLATE(png_ptr, Z_SYNC_FLUSH); 668 669 /* Check for any failure before proceeding. */ 670 if (ret != Z_OK && ret != Z_STREAM_END) 671 { 672 /* Terminate the decompression. */ 673 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; 674 png_ptr->zowner = 0; 675 676 /* This may be a truncated stream (missing or 677 * damaged end code). Treat that as a warning. 678 */ 679 if (png_ptr->row_number >= png_ptr->num_rows || 680 png_ptr->pass > 6) 681 png_warning(png_ptr, "Truncated compressed data in IDAT"); 682 683 else 684 png_error(png_ptr, "Decompression error in IDAT"); 685 686 /* Skip the check on unprocessed input */ 687 return; 688 } 689 690 /* Did inflate output any data? */ 691 if (png_ptr->zstream.next_out != png_ptr->row_buf) 692 { 693 /* Is this unexpected data after the last row? 694 * If it is, artificially terminate the LZ output 695 * here. 696 */ 697 if (png_ptr->row_number >= png_ptr->num_rows || 698 png_ptr->pass > 6) 699 { 700 /* Extra data. */ 701 png_warning(png_ptr, "Extra compressed data in IDAT"); 702 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; 703 png_ptr->zowner = 0; 704 705 /* Do no more processing; skip the unprocessed 706 * input check below. 707 */ 708 return; 709 } 710 711 /* Do we have a complete row? */ 712 if (png_ptr->zstream.avail_out == 0) 713 png_push_process_row(png_ptr); 714 } 715 716 /* And check for the end of the stream. */ 717 if (ret == Z_STREAM_END) 718 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; 719 } 720 721 /* All the data should have been processed, if anything 722 * is left at this point we have bytes of IDAT data 723 * after the zlib end code. 724 */ 725 if (png_ptr->zstream.avail_in > 0) 726 png_warning(png_ptr, "Extra compression data in IDAT"); 727 } 728 729 void /* PRIVATE */ 730 png_push_process_row(png_structrp png_ptr) 731 { 732 /* 1.5.6: row_info moved out of png_struct to a local here. */ 733 png_row_info row_info; 734 735 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ 736 row_info.color_type = png_ptr->color_type; 737 row_info.bit_depth = png_ptr->bit_depth; 738 row_info.channels = png_ptr->channels; 739 row_info.pixel_depth = png_ptr->pixel_depth; 740 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); 741 742 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) 743 { 744 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) 745 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, 746 png_ptr->prev_row + 1, png_ptr->row_buf[0]); 747 else 748 png_error(png_ptr, "bad adaptive filter value"); 749 } 750 751 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before 752 * 1.5.6, while the buffer really is this big in current versions of libpng 753 * it may not be in the future, so this was changed just to copy the 754 * interlaced row count: 755 */ 756 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); 757 758 #ifdef PNG_READ_TRANSFORMS_SUPPORTED 759 if (png_ptr->transformations != 0) 760 png_do_read_transformations(png_ptr, &row_info); 761 #endif 762 763 /* The transformed pixel depth should match the depth now in row_info. */ 764 if (png_ptr->transformed_pixel_depth == 0) 765 { 766 png_ptr->transformed_pixel_depth = row_info.pixel_depth; 767 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) 768 png_error(png_ptr, "progressive row overflow"); 769 } 770 771 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) 772 png_error(png_ptr, "internal progressive row size calculation error"); 773 774 775 #ifdef PNG_READ_INTERLACING_SUPPORTED 776 /* Expand interlaced rows to full size */ 777 if (png_ptr->interlaced != 0 && 778 (png_ptr->transformations & PNG_INTERLACE) != 0) 779 { 780 if (png_ptr->pass < 6) 781 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, 782 png_ptr->transformations); 783 784 switch (png_ptr->pass) 785 { 786 case 0: 787 { 788 int i; 789 for (i = 0; i < 8 && png_ptr->pass == 0; i++) 790 { 791 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 792 png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */ 793 } 794 795 if (png_ptr->pass == 2) /* Pass 1 might be empty */ 796 { 797 for (i = 0; i < 4 && png_ptr->pass == 2; i++) 798 { 799 png_push_have_row(png_ptr, NULL); 800 png_read_push_finish_row(png_ptr); 801 } 802 } 803 804 if (png_ptr->pass == 4 && png_ptr->height <= 4) 805 { 806 for (i = 0; i < 2 && png_ptr->pass == 4; i++) 807 { 808 png_push_have_row(png_ptr, NULL); 809 png_read_push_finish_row(png_ptr); 810 } 811 } 812 813 if (png_ptr->pass == 6 && png_ptr->height <= 4) 814 { 815 png_push_have_row(png_ptr, NULL); 816 png_read_push_finish_row(png_ptr); 817 } 818 819 break; 820 } 821 822 case 1: 823 { 824 int i; 825 for (i = 0; i < 8 && png_ptr->pass == 1; i++) 826 { 827 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 828 png_read_push_finish_row(png_ptr); 829 } 830 831 if (png_ptr->pass == 2) /* Skip top 4 generated rows */ 832 { 833 for (i = 0; i < 4 && png_ptr->pass == 2; i++) 834 { 835 png_push_have_row(png_ptr, NULL); 836 png_read_push_finish_row(png_ptr); 837 } 838 } 839 840 break; 841 } 842 843 case 2: 844 { 845 int i; 846 847 for (i = 0; i < 4 && png_ptr->pass == 2; i++) 848 { 849 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 850 png_read_push_finish_row(png_ptr); 851 } 852 853 for (i = 0; i < 4 && png_ptr->pass == 2; i++) 854 { 855 png_push_have_row(png_ptr, NULL); 856 png_read_push_finish_row(png_ptr); 857 } 858 859 if (png_ptr->pass == 4) /* Pass 3 might be empty */ 860 { 861 for (i = 0; i < 2 && png_ptr->pass == 4; i++) 862 { 863 png_push_have_row(png_ptr, NULL); 864 png_read_push_finish_row(png_ptr); 865 } 866 } 867 868 break; 869 } 870 871 case 3: 872 { 873 int i; 874 875 for (i = 0; i < 4 && png_ptr->pass == 3; i++) 876 { 877 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 878 png_read_push_finish_row(png_ptr); 879 } 880 881 if (png_ptr->pass == 4) /* Skip top two generated rows */ 882 { 883 for (i = 0; i < 2 && png_ptr->pass == 4; i++) 884 { 885 png_push_have_row(png_ptr, NULL); 886 png_read_push_finish_row(png_ptr); 887 } 888 } 889 890 break; 891 } 892 893 case 4: 894 { 895 int i; 896 897 for (i = 0; i < 2 && png_ptr->pass == 4; i++) 898 { 899 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 900 png_read_push_finish_row(png_ptr); 901 } 902 903 for (i = 0; i < 2 && png_ptr->pass == 4; i++) 904 { 905 png_push_have_row(png_ptr, NULL); 906 png_read_push_finish_row(png_ptr); 907 } 908 909 if (png_ptr->pass == 6) /* Pass 5 might be empty */ 910 { 911 png_push_have_row(png_ptr, NULL); 912 png_read_push_finish_row(png_ptr); 913 } 914 915 break; 916 } 917 918 case 5: 919 { 920 int i; 921 922 for (i = 0; i < 2 && png_ptr->pass == 5; i++) 923 { 924 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 925 png_read_push_finish_row(png_ptr); 926 } 927 928 if (png_ptr->pass == 6) /* Skip top generated row */ 929 { 930 png_push_have_row(png_ptr, NULL); 931 png_read_push_finish_row(png_ptr); 932 } 933 934 break; 935 } 936 937 default: 938 case 6: 939 { 940 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 941 png_read_push_finish_row(png_ptr); 942 943 if (png_ptr->pass != 6) 944 break; 945 946 png_push_have_row(png_ptr, NULL); 947 png_read_push_finish_row(png_ptr); 948 } 949 } 950 } 951 else 952 #endif 953 { 954 png_push_have_row(png_ptr, png_ptr->row_buf + 1); 955 png_read_push_finish_row(png_ptr); 956 } 957 } 958 959 void /* PRIVATE */ 960 png_read_push_finish_row(png_structrp png_ptr) 961 { 962 #ifdef PNG_READ_INTERLACING_SUPPORTED 963 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 964 965 /* Start of interlace block */ 966 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; 967 968 /* Offset to next interlace block */ 969 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; 970 971 /* Start of interlace block in the y direction */ 972 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1}; 973 974 /* Offset to next interlace block in the y direction */ 975 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2}; 976 977 /* Height of interlace block. This is not currently used - if you need 978 * it, uncomment it here and in png.h 979 static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1}; 980 */ 981 #endif 982 983 png_ptr->row_number++; 984 if (png_ptr->row_number < png_ptr->num_rows) 985 return; 986 987 #ifdef PNG_READ_INTERLACING_SUPPORTED 988 if (png_ptr->interlaced != 0) 989 { 990 png_ptr->row_number = 0; 991 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); 992 993 do 994 { 995 png_ptr->pass++; 996 if ((png_ptr->pass == 1 && png_ptr->width < 5) || 997 (png_ptr->pass == 3 && png_ptr->width < 3) || 998 (png_ptr->pass == 5 && png_ptr->width < 2)) 999 png_ptr->pass++; 1000 1001 if (png_ptr->pass > 7) 1002 png_ptr->pass--; 1003 1004 if (png_ptr->pass >= 7) 1005 break; 1006 1007 png_ptr->iwidth = (png_ptr->width + 1008 png_pass_inc[png_ptr->pass] - 1 - 1009 png_pass_start[png_ptr->pass]) / 1010 png_pass_inc[png_ptr->pass]; 1011 1012 if ((png_ptr->transformations & PNG_INTERLACE) != 0) 1013 break; 1014 1015 png_ptr->num_rows = (png_ptr->height + 1016 png_pass_yinc[png_ptr->pass] - 1 - 1017 png_pass_ystart[png_ptr->pass]) / 1018 png_pass_yinc[png_ptr->pass]; 1019 1020 } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0); 1021 } 1022 #endif /* READ_INTERLACING */ 1023 } 1024 1025 void /* PRIVATE */ 1026 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr) 1027 { 1028 if (png_ptr->info_fn != NULL) 1029 (*(png_ptr->info_fn))(png_ptr, info_ptr); 1030 } 1031 1032 void /* PRIVATE */ 1033 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr) 1034 { 1035 if (png_ptr->end_fn != NULL) 1036 (*(png_ptr->end_fn))(png_ptr, info_ptr); 1037 } 1038 1039 void /* PRIVATE */ 1040 png_push_have_row(png_structrp png_ptr, png_bytep row) 1041 { 1042 if (png_ptr->row_fn != NULL) 1043 (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number, 1044 (int)png_ptr->pass); 1045 } 1046 1047 #ifdef PNG_READ_INTERLACING_SUPPORTED 1048 void PNGAPI 1049 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row, 1050 png_const_bytep new_row) 1051 { 1052 if (png_ptr == NULL) 1053 return; 1054 1055 /* new_row is a flag here - if it is NULL then the app callback was called 1056 * from an empty row (see the calls to png_struct::row_fn below), otherwise 1057 * it must be png_ptr->row_buf+1 1058 */ 1059 if (new_row != NULL) 1060 png_combine_row(png_ptr, old_row, 1/*blocky display*/); 1061 } 1062 #endif /* READ_INTERLACING */ 1063 1064 void PNGAPI 1065 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr, 1066 png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn, 1067 png_progressive_end_ptr end_fn) 1068 { 1069 if (png_ptr == NULL) 1070 return; 1071 1072 png_ptr->info_fn = info_fn; 1073 png_ptr->row_fn = row_fn; 1074 png_ptr->end_fn = end_fn; 1075 1076 png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer); 1077 } 1078 1079 png_voidp PNGAPI 1080 png_get_progressive_ptr(png_const_structrp png_ptr) 1081 { 1082 if (png_ptr == NULL) 1083 return (NULL); 1084 1085 return png_ptr->io_ptr; 1086 } 1087 #endif /* PROGRESSIVE_READ */ 1088
