1 2 /* pngrutil.c - utilities to read a PNG file 3 * 4 * Last changed in libpng 1.6.10 [March 6, 2014] 5 * Copyright (c) 1998-2014 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 * This file contains routines that are only called from within 14 * libpng itself during the course of reading an image. 15 */ 16 17 #include "pngpriv.h" 18 19 #ifdef PNG_READ_SUPPORTED 20 21 png_uint_32 PNGAPI 22 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf) 23 { 24 png_uint_32 uval = png_get_uint_32(buf); 25 26 if (uval > PNG_UINT_31_MAX) 27 png_error(png_ptr, "PNG unsigned integer out of range"); 28 29 return (uval); 30 } 31 32 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED) 33 /* The following is a variation on the above for use with the fixed 34 * point values used for gAMA and cHRM. Instead of png_error it 35 * issues a warning and returns (-1) - an invalid value because both 36 * gAMA and cHRM use *unsigned* integers for fixed point values. 37 */ 38 #define PNG_FIXED_ERROR (-1) 39 40 static png_fixed_point /* PRIVATE */ 41 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf) 42 { 43 png_uint_32 uval = png_get_uint_32(buf); 44 45 if (uval <= PNG_UINT_31_MAX) 46 return (png_fixed_point)uval; /* known to be in range */ 47 48 /* The caller can turn off the warning by passing NULL. */ 49 if (png_ptr != NULL) 50 png_warning(png_ptr, "PNG fixed point integer out of range"); 51 52 return PNG_FIXED_ERROR; 53 } 54 #endif 55 56 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED 57 /* NOTE: the read macros will obscure these definitions, so that if 58 * PNG_USE_READ_MACROS is set the library will not use them internally, 59 * but the APIs will still be available externally. 60 * 61 * The parentheses around "PNGAPI function_name" in the following three 62 * functions are necessary because they allow the macros to co-exist with 63 * these (unused but exported) functions. 64 */ 65 66 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */ 67 png_uint_32 (PNGAPI 68 png_get_uint_32)(png_const_bytep buf) 69 { 70 png_uint_32 uval = 71 ((png_uint_32)(*(buf )) << 24) + 72 ((png_uint_32)(*(buf + 1)) << 16) + 73 ((png_uint_32)(*(buf + 2)) << 8) + 74 ((png_uint_32)(*(buf + 3)) ) ; 75 76 return uval; 77 } 78 79 /* Grab a signed 32-bit integer from a buffer in big-endian format. The 80 * data is stored in the PNG file in two's complement format and there 81 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore 82 * the following code does a two's complement to native conversion. 83 */ 84 png_int_32 (PNGAPI 85 png_get_int_32)(png_const_bytep buf) 86 { 87 png_uint_32 uval = png_get_uint_32(buf); 88 if ((uval & 0x80000000) == 0) /* non-negative */ 89 return uval; 90 91 uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */ 92 return -(png_int_32)uval; 93 } 94 95 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */ 96 png_uint_16 (PNGAPI 97 png_get_uint_16)(png_const_bytep buf) 98 { 99 /* ANSI-C requires an int value to accomodate at least 16 bits so this 100 * works and allows the compiler not to worry about possible narrowing 101 * on 32 bit systems. (Pre-ANSI systems did not make integers smaller 102 * than 16 bits either.) 103 */ 104 unsigned int val = 105 ((unsigned int)(*buf) << 8) + 106 ((unsigned int)(*(buf + 1))); 107 108 return (png_uint_16)val; 109 } 110 111 #endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */ 112 113 /* Read and check the PNG file signature */ 114 void /* PRIVATE */ 115 png_read_sig(png_structrp png_ptr, png_inforp info_ptr) 116 { 117 png_size_t num_checked, num_to_check; 118 119 /* Exit if the user application does not expect a signature. */ 120 if (png_ptr->sig_bytes >= 8) 121 return; 122 123 num_checked = png_ptr->sig_bytes; 124 num_to_check = 8 - num_checked; 125 126 #ifdef PNG_IO_STATE_SUPPORTED 127 png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE; 128 #endif 129 130 /* The signature must be serialized in a single I/O call. */ 131 png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check); 132 png_ptr->sig_bytes = 8; 133 134 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check)) 135 { 136 if (num_checked < 4 && 137 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4)) 138 png_error(png_ptr, "Not a PNG file"); 139 else 140 png_error(png_ptr, "PNG file corrupted by ASCII conversion"); 141 } 142 if (num_checked < 3) 143 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; 144 } 145 146 /* Read the chunk header (length + type name). 147 * Put the type name into png_ptr->chunk_name, and return the length. 148 */ 149 png_uint_32 /* PRIVATE */ 150 png_read_chunk_header(png_structrp png_ptr) 151 { 152 png_byte buf[8]; 153 png_uint_32 length; 154 155 #ifdef PNG_IO_STATE_SUPPORTED 156 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR; 157 #endif 158 159 /* Read the length and the chunk name. 160 * This must be performed in a single I/O call. 161 */ 162 png_read_data(png_ptr, buf, 8); 163 length = png_get_uint_31(png_ptr, buf); 164 165 /* Put the chunk name into png_ptr->chunk_name. */ 166 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4); 167 168 png_debug2(0, "Reading %lx chunk, length = %lu", 169 (unsigned long)png_ptr->chunk_name, (unsigned long)length); 170 171 /* Reset the crc and run it over the chunk name. */ 172 png_reset_crc(png_ptr); 173 png_calculate_crc(png_ptr, buf + 4, 4); 174 175 /* Check to see if chunk name is valid. */ 176 png_check_chunk_name(png_ptr, png_ptr->chunk_name); 177 178 #ifdef PNG_IO_STATE_SUPPORTED 179 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA; 180 #endif 181 182 return length; 183 } 184 185 /* Read data, and (optionally) run it through the CRC. */ 186 void /* PRIVATE */ 187 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length) 188 { 189 if (png_ptr == NULL) 190 return; 191 192 png_read_data(png_ptr, buf, length); 193 png_calculate_crc(png_ptr, buf, length); 194 } 195 196 /* Optionally skip data and then check the CRC. Depending on whether we 197 * are reading an ancillary or critical chunk, and how the program has set 198 * things up, we may calculate the CRC on the data and print a message. 199 * Returns '1' if there was a CRC error, '0' otherwise. 200 */ 201 int /* PRIVATE */ 202 png_crc_finish(png_structrp png_ptr, png_uint_32 skip) 203 { 204 /* The size of the local buffer for inflate is a good guess as to a 205 * reasonable size to use for buffering reads from the application. 206 */ 207 while (skip > 0) 208 { 209 png_uint_32 len; 210 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE]; 211 212 len = (sizeof tmpbuf); 213 if (len > skip) 214 len = skip; 215 skip -= len; 216 217 png_crc_read(png_ptr, tmpbuf, len); 218 } 219 220 if (png_crc_error(png_ptr)) 221 { 222 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ? 223 !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) : 224 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)) 225 { 226 png_chunk_warning(png_ptr, "CRC error"); 227 } 228 229 else 230 png_chunk_error(png_ptr, "CRC error"); 231 232 return (1); 233 } 234 235 return (0); 236 } 237 238 #ifdef PNG_INDEX_SUPPORTED 239 /* If tile index is used to skip over data and decode a partial image 240 * the crc value may be incorrect. 241 * The crc will only be calculated for the partial data read, 242 * not the entire data, which will result in an incorrect crc value. 243 * This function treats a png_crc_error as a warning, as opposed to the 244 * original function png_crc_finish, which will treat it as an error. 245 */ 246 int /* PRIVATE */ 247 png_opt_crc_finish(png_structrp png_ptr, png_uint_32 skip) 248 { 249 while (skip > 0) 250 { 251 png_uint_32 len; 252 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE]; 253 254 len = (sizeof tmpbuf); 255 if (len > skip) 256 len = skip; 257 skip -= len; 258 259 png_crc_read(png_ptr, tmpbuf, len); 260 } 261 262 if (png_crc_error(png_ptr)) 263 { 264 png_chunk_warning(png_ptr, "CRC error"); 265 return (1); 266 } 267 268 return (0); 269 } 270 #endif 271 272 /* Compare the CRC stored in the PNG file with that calculated by libpng from 273 * the data it has read thus far. 274 */ 275 int /* PRIVATE */ 276 png_crc_error(png_structrp png_ptr) 277 { 278 png_byte crc_bytes[4]; 279 png_uint_32 crc; 280 int need_crc = 1; 281 282 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)) 283 { 284 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == 285 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) 286 need_crc = 0; 287 } 288 289 else /* critical */ 290 { 291 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) 292 need_crc = 0; 293 } 294 295 #ifdef PNG_IO_STATE_SUPPORTED 296 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC; 297 #endif 298 299 /* The chunk CRC must be serialized in a single I/O call. */ 300 png_read_data(png_ptr, crc_bytes, 4); 301 302 if (need_crc) 303 { 304 crc = png_get_uint_32(crc_bytes); 305 return ((int)(crc != png_ptr->crc)); 306 } 307 308 else 309 return (0); 310 } 311 312 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\ 313 defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\ 314 defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\ 315 defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED) 316 /* Manage the read buffer; this simply reallocates the buffer if it is not small 317 * enough (or if it is not allocated). The routine returns a pointer to the 318 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else 319 * it will call png_error (via png_malloc) on failure. (warn == 2 means 320 * 'silent'). 321 */ 322 static png_bytep 323 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn) 324 { 325 png_bytep buffer = png_ptr->read_buffer; 326 327 if (buffer != NULL && new_size > png_ptr->read_buffer_size) 328 { 329 png_ptr->read_buffer = NULL; 330 png_ptr->read_buffer = NULL; 331 png_ptr->read_buffer_size = 0; 332 png_free(png_ptr, buffer); 333 buffer = NULL; 334 } 335 336 if (buffer == NULL) 337 { 338 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size)); 339 340 if (buffer != NULL) 341 { 342 png_ptr->read_buffer = buffer; 343 png_ptr->read_buffer_size = new_size; 344 } 345 346 else if (warn < 2) /* else silent */ 347 { 348 if (warn) 349 png_chunk_warning(png_ptr, "insufficient memory to read chunk"); 350 351 else 352 png_chunk_error(png_ptr, "insufficient memory to read chunk"); 353 } 354 } 355 356 return buffer; 357 } 358 #endif /* PNG_READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */ 359 360 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves 361 * decompression. Returns Z_OK on success, else a zlib error code. It checks 362 * the owner but, in final release builds, just issues a warning if some other 363 * chunk apparently owns the stream. Prior to release it does a png_error. 364 */ 365 static int 366 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner) 367 { 368 if (png_ptr->zowner != 0) 369 { 370 char msg[64]; 371 372 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner); 373 /* So the message that results is "<chunk> using zstream"; this is an 374 * internal error, but is very useful for debugging. i18n requirements 375 * are minimal. 376 */ 377 (void)png_safecat(msg, (sizeof msg), 4, " using zstream"); 378 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC 379 png_chunk_warning(png_ptr, msg); 380 png_ptr->zowner = 0; 381 # else 382 png_chunk_error(png_ptr, msg); 383 # endif 384 } 385 386 /* Implementation note: unlike 'png_deflate_claim' this internal function 387 * does not take the size of the data as an argument. Some efficiency could 388 * be gained by using this when it is known *if* the zlib stream itself does 389 * not record the number; however, this is an illusion: the original writer 390 * of the PNG may have selected a lower window size, and we really must 391 * follow that because, for systems with with limited capabilities, we 392 * would otherwise reject the application's attempts to use a smaller window 393 * size (zlib doesn't have an interface to say "this or lower"!). 394 * 395 * inflateReset2 was added to zlib 1.2.4; before this the window could not be 396 * reset, therefore it is necessary to always allocate the maximum window 397 * size with earlier zlibs just in case later compressed chunks need it. 398 */ 399 { 400 int ret; /* zlib return code */ 401 # if PNG_ZLIB_VERNUM >= 0x1240 402 403 # if defined(PNG_SET_OPTION_SUPPORTED) && \ 404 defined(PNG_MAXIMUM_INFLATE_WINDOW) 405 int window_bits; 406 407 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) == 408 PNG_OPTION_ON) 409 window_bits = 15; 410 411 else 412 window_bits = 0; 413 # else 414 # define window_bits 0 415 # endif 416 # endif 417 418 /* Set this for safety, just in case the previous owner left pointers to 419 * memory allocations. 420 */ 421 png_ptr->zstream.next_in = NULL; 422 png_ptr->zstream.avail_in = 0; 423 png_ptr->zstream.next_out = NULL; 424 png_ptr->zstream.avail_out = 0; 425 426 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) 427 { 428 # if PNG_ZLIB_VERNUM < 0x1240 429 ret = inflateReset(&png_ptr->zstream); 430 # else 431 ret = inflateReset2(&png_ptr->zstream, window_bits); 432 # endif 433 } 434 435 else 436 { 437 # if PNG_ZLIB_VERNUM < 0x1240 438 ret = inflateInit(&png_ptr->zstream); 439 # else 440 ret = inflateInit2(&png_ptr->zstream, window_bits); 441 # endif 442 443 if (ret == Z_OK) 444 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED; 445 } 446 447 if (ret == Z_OK) 448 png_ptr->zowner = owner; 449 450 else 451 png_zstream_error(png_ptr, ret); 452 453 return ret; 454 } 455 456 # ifdef window_bits 457 # undef window_bits 458 # endif 459 } 460 461 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED 462 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to 463 * allow the caller to do multiple calls if required. If the 'finish' flag is 464 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must 465 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and 466 * Z_OK or Z_STREAM_END will be returned on success. 467 * 468 * The input and output sizes are updated to the actual amounts of data consumed 469 * or written, not the amount available (as in a z_stream). The data pointers 470 * are not changed, so the next input is (data+input_size) and the next 471 * available output is (output+output_size). 472 */ 473 static int 474 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish, 475 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr, 476 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr) 477 { 478 if (png_ptr->zowner == owner) /* Else not claimed */ 479 { 480 int ret; 481 png_alloc_size_t avail_out = *output_size_ptr; 482 png_uint_32 avail_in = *input_size_ptr; 483 484 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it 485 * can't even necessarily handle 65536 bytes) because the type uInt is 486 * "16 bits or more". Consequently it is necessary to chunk the input to 487 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the 488 * maximum value that can be stored in a uInt.) It is possible to set 489 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have 490 * a performance advantage, because it reduces the amount of data accessed 491 * at each step and that may give the OS more time to page it in. 492 */ 493 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); 494 /* avail_in and avail_out are set below from 'size' */ 495 png_ptr->zstream.avail_in = 0; 496 png_ptr->zstream.avail_out = 0; 497 498 /* Read directly into the output if it is available (this is set to 499 * a local buffer below if output is NULL). 500 */ 501 if (output != NULL) 502 png_ptr->zstream.next_out = output; 503 504 do 505 { 506 uInt avail; 507 Byte local_buffer[PNG_INFLATE_BUF_SIZE]; 508 509 /* zlib INPUT BUFFER */ 510 /* The setting of 'avail_in' used to be outside the loop; by setting it 511 * inside it is possible to chunk the input to zlib and simply rely on 512 * zlib to advance the 'next_in' pointer. This allows arbitrary 513 * amounts of data to be passed through zlib at the unavoidable cost of 514 * requiring a window save (memcpy of up to 32768 output bytes) 515 * every ZLIB_IO_MAX input bytes. 516 */ 517 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */ 518 519 avail = ZLIB_IO_MAX; 520 521 if (avail_in < avail) 522 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */ 523 524 avail_in -= avail; 525 png_ptr->zstream.avail_in = avail; 526 527 /* zlib OUTPUT BUFFER */ 528 avail_out += png_ptr->zstream.avail_out; /* not written last time */ 529 530 avail = ZLIB_IO_MAX; /* maximum zlib can process */ 531 532 if (output == NULL) 533 { 534 /* Reset the output buffer each time round if output is NULL and 535 * make available the full buffer, up to 'remaining_space' 536 */ 537 png_ptr->zstream.next_out = local_buffer; 538 if ((sizeof local_buffer) < avail) 539 avail = (sizeof local_buffer); 540 } 541 542 if (avail_out < avail) 543 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */ 544 545 png_ptr->zstream.avail_out = avail; 546 avail_out -= avail; 547 548 /* zlib inflate call */ 549 /* In fact 'avail_out' may be 0 at this point, that happens at the end 550 * of the read when the final LZ end code was not passed at the end of 551 * the previous chunk of input data. Tell zlib if we have reached the 552 * end of the output buffer. 553 */ 554 ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH : 555 (finish ? Z_FINISH : Z_SYNC_FLUSH)); 556 } while (ret == Z_OK); 557 558 /* For safety kill the local buffer pointer now */ 559 if (output == NULL) 560 png_ptr->zstream.next_out = NULL; 561 562 /* Claw back the 'size' and 'remaining_space' byte counts. */ 563 avail_in += png_ptr->zstream.avail_in; 564 avail_out += png_ptr->zstream.avail_out; 565 566 /* Update the input and output sizes; the updated values are the amount 567 * consumed or written, effectively the inverse of what zlib uses. 568 */ 569 if (avail_out > 0) 570 *output_size_ptr -= avail_out; 571 572 if (avail_in > 0) 573 *input_size_ptr -= avail_in; 574 575 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */ 576 png_zstream_error(png_ptr, ret); 577 return ret; 578 } 579 580 else 581 { 582 /* This is a bad internal error. The recovery assigns to the zstream msg 583 * pointer, which is not owned by the caller, but this is safe; it's only 584 * used on errors! 585 */ 586 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed"); 587 return Z_STREAM_ERROR; 588 } 589 } 590 591 /* 592 * Decompress trailing data in a chunk. The assumption is that read_buffer 593 * points at an allocated area holding the contents of a chunk with a 594 * trailing compressed part. What we get back is an allocated area 595 * holding the original prefix part and an uncompressed version of the 596 * trailing part (the malloc area passed in is freed). 597 */ 598 static int 599 png_decompress_chunk(png_structrp png_ptr, 600 png_uint_32 chunklength, png_uint_32 prefix_size, 601 png_alloc_size_t *newlength /* must be initialized to the maximum! */, 602 int terminate /*add a '\0' to the end of the uncompressed data*/) 603 { 604 /* TODO: implement different limits for different types of chunk. 605 * 606 * The caller supplies *newlength set to the maximum length of the 607 * uncompressed data, but this routine allocates space for the prefix and 608 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is 609 * limited only by the maximum chunk size. 610 */ 611 png_alloc_size_t limit = PNG_SIZE_MAX; 612 613 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED 614 if (png_ptr->user_chunk_malloc_max > 0 && 615 png_ptr->user_chunk_malloc_max < limit) 616 limit = png_ptr->user_chunk_malloc_max; 617 # elif PNG_USER_CHUNK_MALLOC_MAX > 0 618 if (PNG_USER_CHUNK_MALLOC_MAX < limit) 619 limit = PNG_USER_CHUNK_MALLOC_MAX; 620 # endif 621 622 if (limit >= prefix_size + (terminate != 0)) 623 { 624 int ret; 625 626 limit -= prefix_size + (terminate != 0); 627 628 if (limit < *newlength) 629 *newlength = limit; 630 631 /* Now try to claim the stream. */ 632 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name); 633 634 if (ret == Z_OK) 635 { 636 png_uint_32 lzsize = chunklength - prefix_size; 637 638 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/, 639 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize, 640 /* output: */ NULL, newlength); 641 642 if (ret == Z_STREAM_END) 643 { 644 /* Use 'inflateReset' here, not 'inflateReset2' because this 645 * preserves the previously decided window size (otherwise it would 646 * be necessary to store the previous window size.) In practice 647 * this doesn't matter anyway, because png_inflate will call inflate 648 * with Z_FINISH in almost all cases, so the window will not be 649 * maintained. 650 */ 651 if (inflateReset(&png_ptr->zstream) == Z_OK) 652 { 653 /* Because of the limit checks above we know that the new, 654 * expanded, size will fit in a size_t (let alone an 655 * png_alloc_size_t). Use png_malloc_base here to avoid an 656 * extra OOM message. 657 */ 658 png_alloc_size_t new_size = *newlength; 659 png_alloc_size_t buffer_size = prefix_size + new_size + 660 (terminate != 0); 661 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr, 662 buffer_size)); 663 664 if (text != NULL) 665 { 666 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/, 667 png_ptr->read_buffer + prefix_size, &lzsize, 668 text + prefix_size, newlength); 669 670 if (ret == Z_STREAM_END) 671 { 672 if (new_size == *newlength) 673 { 674 if (terminate) 675 text[prefix_size + *newlength] = 0; 676 677 if (prefix_size > 0) 678 memcpy(text, png_ptr->read_buffer, prefix_size); 679 680 { 681 png_bytep old_ptr = png_ptr->read_buffer; 682 683 png_ptr->read_buffer = text; 684 png_ptr->read_buffer_size = buffer_size; 685 text = old_ptr; /* freed below */ 686 } 687 } 688 689 else 690 { 691 /* The size changed on the second read, there can be no 692 * guarantee that anything is correct at this point. 693 * The 'msg' pointer has been set to "unexpected end of 694 * LZ stream", which is fine, but return an error code 695 * that the caller won't accept. 696 */ 697 ret = PNG_UNEXPECTED_ZLIB_RETURN; 698 } 699 } 700 701 else if (ret == Z_OK) 702 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */ 703 704 /* Free the text pointer (this is the old read_buffer on 705 * success) 706 */ 707 png_free(png_ptr, text); 708 709 /* This really is very benign, but it's still an error because 710 * the extra space may otherwise be used as a Trojan Horse. 711 */ 712 if (ret == Z_STREAM_END && 713 chunklength - prefix_size != lzsize) 714 png_chunk_benign_error(png_ptr, "extra compressed data"); 715 } 716 717 else 718 { 719 /* Out of memory allocating the buffer */ 720 ret = Z_MEM_ERROR; 721 png_zstream_error(png_ptr, Z_MEM_ERROR); 722 } 723 } 724 725 else 726 { 727 /* inflateReset failed, store the error message */ 728 png_zstream_error(png_ptr, ret); 729 730 if (ret == Z_STREAM_END) 731 ret = PNG_UNEXPECTED_ZLIB_RETURN; 732 } 733 } 734 735 else if (ret == Z_OK) 736 ret = PNG_UNEXPECTED_ZLIB_RETURN; 737 738 /* Release the claimed stream */ 739 png_ptr->zowner = 0; 740 } 741 742 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */ 743 ret = PNG_UNEXPECTED_ZLIB_RETURN; 744 745 return ret; 746 } 747 748 else 749 { 750 /* Application/configuration limits exceeded */ 751 png_zstream_error(png_ptr, Z_MEM_ERROR); 752 return Z_MEM_ERROR; 753 } 754 } 755 #endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */ 756 757 #ifdef PNG_READ_iCCP_SUPPORTED 758 /* Perform a partial read and decompress, producing 'avail_out' bytes and 759 * reading from the current chunk as required. 760 */ 761 static int 762 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size, 763 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size, 764 int finish) 765 { 766 if (png_ptr->zowner == png_ptr->chunk_name) 767 { 768 int ret; 769 770 /* next_in and avail_in must have been initialized by the caller. */ 771 png_ptr->zstream.next_out = next_out; 772 png_ptr->zstream.avail_out = 0; /* set in the loop */ 773 774 do 775 { 776 if (png_ptr->zstream.avail_in == 0) 777 { 778 if (read_size > *chunk_bytes) 779 read_size = (uInt)*chunk_bytes; 780 *chunk_bytes -= read_size; 781 782 if (read_size > 0) 783 png_crc_read(png_ptr, read_buffer, read_size); 784 785 png_ptr->zstream.next_in = read_buffer; 786 png_ptr->zstream.avail_in = read_size; 787 } 788 789 if (png_ptr->zstream.avail_out == 0) 790 { 791 uInt avail = ZLIB_IO_MAX; 792 if (avail > *out_size) 793 avail = (uInt)*out_size; 794 *out_size -= avail; 795 796 png_ptr->zstream.avail_out = avail; 797 } 798 799 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all 800 * the available output is produced; this allows reading of truncated 801 * streams. 802 */ 803 ret = inflate(&png_ptr->zstream, 804 *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH)); 805 } 806 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0)); 807 808 *out_size += png_ptr->zstream.avail_out; 809 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */ 810 811 /* Ensure the error message pointer is always set: */ 812 png_zstream_error(png_ptr, ret); 813 return ret; 814 } 815 816 else 817 { 818 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed"); 819 return Z_STREAM_ERROR; 820 } 821 } 822 #endif 823 824 /* Read and check the IDHR chunk */ 825 void /* PRIVATE */ 826 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 827 { 828 png_byte buf[13]; 829 png_uint_32 width, height; 830 int bit_depth, color_type, compression_type, filter_type; 831 int interlace_type; 832 833 png_debug(1, "in png_handle_IHDR"); 834 835 if (png_ptr->mode & PNG_HAVE_IHDR) 836 png_chunk_error(png_ptr, "out of place"); 837 838 /* Check the length */ 839 if (length != 13) 840 png_chunk_error(png_ptr, "invalid"); 841 842 png_ptr->mode |= PNG_HAVE_IHDR; 843 844 png_crc_read(png_ptr, buf, 13); 845 png_crc_finish(png_ptr, 0); 846 847 width = png_get_uint_31(png_ptr, buf); 848 height = png_get_uint_31(png_ptr, buf + 4); 849 bit_depth = buf[8]; 850 color_type = buf[9]; 851 compression_type = buf[10]; 852 filter_type = buf[11]; 853 interlace_type = buf[12]; 854 855 /* Set internal variables */ 856 png_ptr->width = width; 857 png_ptr->height = height; 858 png_ptr->bit_depth = (png_byte)bit_depth; 859 png_ptr->interlaced = (png_byte)interlace_type; 860 png_ptr->color_type = (png_byte)color_type; 861 #ifdef PNG_MNG_FEATURES_SUPPORTED 862 png_ptr->filter_type = (png_byte)filter_type; 863 #endif 864 png_ptr->compression_type = (png_byte)compression_type; 865 866 /* Find number of channels */ 867 switch (png_ptr->color_type) 868 { 869 default: /* invalid, png_set_IHDR calls png_error */ 870 case PNG_COLOR_TYPE_GRAY: 871 case PNG_COLOR_TYPE_PALETTE: 872 png_ptr->channels = 1; 873 break; 874 875 case PNG_COLOR_TYPE_RGB: 876 png_ptr->channels = 3; 877 break; 878 879 case PNG_COLOR_TYPE_GRAY_ALPHA: 880 png_ptr->channels = 2; 881 break; 882 883 case PNG_COLOR_TYPE_RGB_ALPHA: 884 png_ptr->channels = 4; 885 break; 886 } 887 888 /* Set up other useful info */ 889 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * 890 png_ptr->channels); 891 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width); 892 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth); 893 png_debug1(3, "channels = %d", png_ptr->channels); 894 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes); 895 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, 896 color_type, interlace_type, compression_type, filter_type); 897 } 898 899 /* Read and check the palette */ 900 void /* PRIVATE */ 901 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 902 { 903 png_color palette[PNG_MAX_PALETTE_LENGTH]; 904 int num, i; 905 #ifdef PNG_POINTER_INDEXING_SUPPORTED 906 png_colorp pal_ptr; 907 #endif 908 909 png_debug(1, "in png_handle_PLTE"); 910 911 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 912 png_chunk_error(png_ptr, "missing IHDR"); 913 914 /* Moved to before the 'after IDAT' check below because otherwise duplicate 915 * PLTE chunks are potentially ignored (the spec says there shall not be more 916 * than one PLTE, the error is not treated as benign, so this check trumps 917 * the requirement that PLTE appears before IDAT.) 918 */ 919 else if (png_ptr->mode & PNG_HAVE_PLTE) 920 png_chunk_error(png_ptr, "duplicate"); 921 922 else if (png_ptr->mode & PNG_HAVE_IDAT) 923 { 924 /* This is benign because the non-benign error happened before, when an 925 * IDAT was encountered in a color-mapped image with no PLTE. 926 */ 927 png_crc_finish(png_ptr, length); 928 png_chunk_benign_error(png_ptr, "out of place"); 929 return; 930 } 931 932 png_ptr->mode |= PNG_HAVE_PLTE; 933 934 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) 935 { 936 png_crc_finish(png_ptr, length); 937 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG"); 938 return; 939 } 940 941 #ifndef PNG_READ_OPT_PLTE_SUPPORTED 942 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE) 943 { 944 png_crc_finish(png_ptr, length); 945 return; 946 } 947 #endif 948 949 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3) 950 { 951 png_crc_finish(png_ptr, length); 952 953 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE) 954 png_chunk_benign_error(png_ptr, "invalid"); 955 956 else 957 png_chunk_error(png_ptr, "invalid"); 958 959 return; 960 } 961 962 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */ 963 num = (int)length / 3; 964 965 #ifdef PNG_POINTER_INDEXING_SUPPORTED 966 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++) 967 { 968 png_byte buf[3]; 969 970 png_crc_read(png_ptr, buf, 3); 971 pal_ptr->red = buf[0]; 972 pal_ptr->green = buf[1]; 973 pal_ptr->blue = buf[2]; 974 } 975 #else 976 for (i = 0; i < num; i++) 977 { 978 png_byte buf[3]; 979 980 png_crc_read(png_ptr, buf, 3); 981 /* Don't depend upon png_color being any order */ 982 palette[i].red = buf[0]; 983 palette[i].green = buf[1]; 984 palette[i].blue = buf[2]; 985 } 986 #endif 987 988 /* If we actually need the PLTE chunk (ie for a paletted image), we do 989 * whatever the normal CRC configuration tells us. However, if we 990 * have an RGB image, the PLTE can be considered ancillary, so 991 * we will act as though it is. 992 */ 993 #ifndef PNG_READ_OPT_PLTE_SUPPORTED 994 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 995 #endif 996 { 997 png_crc_finish(png_ptr, 0); 998 } 999 1000 #ifndef PNG_READ_OPT_PLTE_SUPPORTED 1001 else if (png_crc_error(png_ptr)) /* Only if we have a CRC error */ 1002 { 1003 /* If we don't want to use the data from an ancillary chunk, 1004 * we have two options: an error abort, or a warning and we 1005 * ignore the data in this chunk (which should be OK, since 1006 * it's considered ancillary for a RGB or RGBA image). 1007 * 1008 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the 1009 * chunk type to determine whether to check the ancillary or the critical 1010 * flags. 1011 */ 1012 if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE)) 1013 { 1014 if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) 1015 return; 1016 1017 else 1018 png_chunk_error(png_ptr, "CRC error"); 1019 } 1020 1021 /* Otherwise, we (optionally) emit a warning and use the chunk. */ 1022 else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) 1023 png_chunk_warning(png_ptr, "CRC error"); 1024 } 1025 #endif 1026 1027 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its 1028 * own copy of the palette. This has the side effect that when png_start_row 1029 * is called (this happens after any call to png_read_update_info) the 1030 * info_ptr palette gets changed. This is extremely unexpected and 1031 * confusing. 1032 * 1033 * Fix this by not sharing the palette in this way. 1034 */ 1035 png_set_PLTE(png_ptr, info_ptr, palette, num); 1036 1037 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before 1038 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely 1039 * checked the apparent validity of a tRNS chunk inserted before PLTE on a 1040 * palette PNG. 1.6.0 attempts to rigorously follow the standard and 1041 * therefore does a benign error if the erroneous condition is detected *and* 1042 * cancels the tRNS if the benign error returns. The alternative is to 1043 * amend the standard since it would be rather hypocritical of the standards 1044 * maintainers to ignore it. 1045 */ 1046 #ifdef PNG_READ_tRNS_SUPPORTED 1047 if (png_ptr->num_trans > 0 || 1048 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)) 1049 { 1050 /* Cancel this because otherwise it would be used if the transforms 1051 * require it. Don't cancel the 'valid' flag because this would prevent 1052 * detection of duplicate chunks. 1053 */ 1054 png_ptr->num_trans = 0; 1055 1056 if (info_ptr != NULL) 1057 info_ptr->num_trans = 0; 1058 1059 png_chunk_benign_error(png_ptr, "tRNS must be after"); 1060 } 1061 #endif 1062 1063 #ifdef PNG_READ_hIST_SUPPORTED 1064 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0) 1065 png_chunk_benign_error(png_ptr, "hIST must be after"); 1066 #endif 1067 1068 #ifdef PNG_READ_bKGD_SUPPORTED 1069 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0) 1070 png_chunk_benign_error(png_ptr, "bKGD must be after"); 1071 #endif 1072 } 1073 1074 void /* PRIVATE */ 1075 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1076 { 1077 png_debug(1, "in png_handle_IEND"); 1078 1079 if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT)) 1080 png_chunk_error(png_ptr, "out of place"); 1081 1082 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND); 1083 1084 png_crc_finish(png_ptr, length); 1085 1086 if (length != 0) 1087 png_chunk_benign_error(png_ptr, "invalid"); 1088 1089 PNG_UNUSED(info_ptr) 1090 } 1091 1092 #ifdef PNG_READ_gAMA_SUPPORTED 1093 void /* PRIVATE */ 1094 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1095 { 1096 png_fixed_point igamma; 1097 png_byte buf[4]; 1098 1099 png_debug(1, "in png_handle_gAMA"); 1100 1101 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1102 png_chunk_error(png_ptr, "missing IHDR"); 1103 1104 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) 1105 { 1106 png_crc_finish(png_ptr, length); 1107 png_chunk_benign_error(png_ptr, "out of place"); 1108 return; 1109 } 1110 1111 if (length != 4) 1112 { 1113 png_crc_finish(png_ptr, length); 1114 png_chunk_benign_error(png_ptr, "invalid"); 1115 return; 1116 } 1117 1118 png_crc_read(png_ptr, buf, 4); 1119 1120 if (png_crc_finish(png_ptr, 0)) 1121 return; 1122 1123 igamma = png_get_fixed_point(NULL, buf); 1124 1125 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma); 1126 png_colorspace_sync(png_ptr, info_ptr); 1127 } 1128 #endif 1129 1130 #ifdef PNG_READ_sBIT_SUPPORTED 1131 void /* PRIVATE */ 1132 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1133 { 1134 unsigned int truelen, i; 1135 png_byte sample_depth; 1136 png_byte buf[4]; 1137 1138 png_debug(1, "in png_handle_sBIT"); 1139 1140 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1141 png_chunk_error(png_ptr, "missing IHDR"); 1142 1143 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) 1144 { 1145 png_crc_finish(png_ptr, length); 1146 png_chunk_benign_error(png_ptr, "out of place"); 1147 return; 1148 } 1149 1150 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT)) 1151 { 1152 png_crc_finish(png_ptr, length); 1153 png_chunk_benign_error(png_ptr, "duplicate"); 1154 return; 1155 } 1156 1157 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1158 { 1159 truelen = 3; 1160 sample_depth = 8; 1161 } 1162 1163 else 1164 { 1165 truelen = png_ptr->channels; 1166 sample_depth = png_ptr->bit_depth; 1167 } 1168 1169 if (length != truelen || length > 4) 1170 { 1171 png_chunk_benign_error(png_ptr, "invalid"); 1172 png_crc_finish(png_ptr, length); 1173 return; 1174 } 1175 1176 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth; 1177 png_crc_read(png_ptr, buf, truelen); 1178 1179 if (png_crc_finish(png_ptr, 0)) 1180 return; 1181 1182 for (i=0; i<truelen; ++i) 1183 if (buf[i] == 0 || buf[i] > sample_depth) 1184 { 1185 png_chunk_benign_error(png_ptr, "invalid"); 1186 return; 1187 } 1188 1189 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) 1190 { 1191 png_ptr->sig_bit.red = buf[0]; 1192 png_ptr->sig_bit.green = buf[1]; 1193 png_ptr->sig_bit.blue = buf[2]; 1194 png_ptr->sig_bit.alpha = buf[3]; 1195 } 1196 1197 else 1198 { 1199 png_ptr->sig_bit.gray = buf[0]; 1200 png_ptr->sig_bit.red = buf[0]; 1201 png_ptr->sig_bit.green = buf[0]; 1202 png_ptr->sig_bit.blue = buf[0]; 1203 png_ptr->sig_bit.alpha = buf[1]; 1204 } 1205 1206 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit)); 1207 } 1208 #endif 1209 1210 #ifdef PNG_READ_cHRM_SUPPORTED 1211 void /* PRIVATE */ 1212 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1213 { 1214 png_byte buf[32]; 1215 png_xy xy; 1216 1217 png_debug(1, "in png_handle_cHRM"); 1218 1219 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1220 png_chunk_error(png_ptr, "missing IHDR"); 1221 1222 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) 1223 { 1224 png_crc_finish(png_ptr, length); 1225 png_chunk_benign_error(png_ptr, "out of place"); 1226 return; 1227 } 1228 1229 if (length != 32) 1230 { 1231 png_crc_finish(png_ptr, length); 1232 png_chunk_benign_error(png_ptr, "invalid"); 1233 return; 1234 } 1235 1236 png_crc_read(png_ptr, buf, 32); 1237 1238 if (png_crc_finish(png_ptr, 0)) 1239 return; 1240 1241 xy.whitex = png_get_fixed_point(NULL, buf); 1242 xy.whitey = png_get_fixed_point(NULL, buf + 4); 1243 xy.redx = png_get_fixed_point(NULL, buf + 8); 1244 xy.redy = png_get_fixed_point(NULL, buf + 12); 1245 xy.greenx = png_get_fixed_point(NULL, buf + 16); 1246 xy.greeny = png_get_fixed_point(NULL, buf + 20); 1247 xy.bluex = png_get_fixed_point(NULL, buf + 24); 1248 xy.bluey = png_get_fixed_point(NULL, buf + 28); 1249 1250 if (xy.whitex == PNG_FIXED_ERROR || 1251 xy.whitey == PNG_FIXED_ERROR || 1252 xy.redx == PNG_FIXED_ERROR || 1253 xy.redy == PNG_FIXED_ERROR || 1254 xy.greenx == PNG_FIXED_ERROR || 1255 xy.greeny == PNG_FIXED_ERROR || 1256 xy.bluex == PNG_FIXED_ERROR || 1257 xy.bluey == PNG_FIXED_ERROR) 1258 { 1259 png_chunk_benign_error(png_ptr, "invalid values"); 1260 return; 1261 } 1262 1263 /* If a colorspace error has already been output skip this chunk */ 1264 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) 1265 return; 1266 1267 if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) 1268 { 1269 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; 1270 png_colorspace_sync(png_ptr, info_ptr); 1271 png_chunk_benign_error(png_ptr, "duplicate"); 1272 return; 1273 } 1274 1275 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM; 1276 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy, 1277 1/*prefer cHRM values*/); 1278 png_colorspace_sync(png_ptr, info_ptr); 1279 } 1280 #endif 1281 1282 #ifdef PNG_READ_sRGB_SUPPORTED 1283 void /* PRIVATE */ 1284 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1285 { 1286 png_byte intent; 1287 1288 png_debug(1, "in png_handle_sRGB"); 1289 1290 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1291 png_chunk_error(png_ptr, "missing IHDR"); 1292 1293 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) 1294 { 1295 png_crc_finish(png_ptr, length); 1296 png_chunk_benign_error(png_ptr, "out of place"); 1297 return; 1298 } 1299 1300 if (length != 1) 1301 { 1302 png_crc_finish(png_ptr, length); 1303 png_chunk_benign_error(png_ptr, "invalid"); 1304 return; 1305 } 1306 1307 png_crc_read(png_ptr, &intent, 1); 1308 1309 if (png_crc_finish(png_ptr, 0)) 1310 return; 1311 1312 /* If a colorspace error has already been output skip this chunk */ 1313 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) 1314 return; 1315 1316 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect 1317 * this. 1318 */ 1319 if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) 1320 { 1321 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; 1322 png_colorspace_sync(png_ptr, info_ptr); 1323 png_chunk_benign_error(png_ptr, "too many profiles"); 1324 return; 1325 } 1326 1327 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent); 1328 png_colorspace_sync(png_ptr, info_ptr); 1329 } 1330 #endif /* PNG_READ_sRGB_SUPPORTED */ 1331 1332 #ifdef PNG_READ_iCCP_SUPPORTED 1333 void /* PRIVATE */ 1334 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1335 /* Note: this does not properly handle profiles that are > 64K under DOS */ 1336 { 1337 png_const_charp errmsg = NULL; /* error message output, or no error */ 1338 int finished = 0; /* crc checked */ 1339 1340 png_debug(1, "in png_handle_iCCP"); 1341 1342 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1343 png_chunk_error(png_ptr, "missing IHDR"); 1344 1345 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) 1346 { 1347 png_crc_finish(png_ptr, length); 1348 png_chunk_benign_error(png_ptr, "out of place"); 1349 return; 1350 } 1351 1352 /* Consistent with all the above colorspace handling an obviously *invalid* 1353 * chunk is just ignored, so does not invalidate the color space. An 1354 * alternative is to set the 'invalid' flags at the start of this routine 1355 * and only clear them in they were not set before and all the tests pass. 1356 * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4 1357 * byte checksum. The keyword must be one character and there is a 1358 * terminator (0) byte and the compression method. 1359 */ 1360 if (length < 9) 1361 { 1362 png_crc_finish(png_ptr, length); 1363 png_chunk_benign_error(png_ptr, "too short"); 1364 return; 1365 } 1366 1367 /* If a colorspace error has already been output skip this chunk */ 1368 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) 1369 { 1370 png_crc_finish(png_ptr, length); 1371 return; 1372 } 1373 1374 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect 1375 * this. 1376 */ 1377 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0) 1378 { 1379 uInt read_length, keyword_length; 1380 char keyword[81]; 1381 1382 /* Find the keyword; the keyword plus separator and compression method 1383 * bytes can be at most 81 characters long. 1384 */ 1385 read_length = 81; /* maximum */ 1386 if (read_length > length) 1387 read_length = (uInt)length; 1388 1389 png_crc_read(png_ptr, (png_bytep)keyword, read_length); 1390 length -= read_length; 1391 1392 keyword_length = 0; 1393 while (keyword_length < 80 && keyword_length < read_length && 1394 keyword[keyword_length] != 0) 1395 ++keyword_length; 1396 1397 /* TODO: make the keyword checking common */ 1398 if (keyword_length >= 1 && keyword_length <= 79) 1399 { 1400 /* We only understand '0' compression - deflate - so if we get a 1401 * different value we can't safely decode the chunk. 1402 */ 1403 if (keyword_length+1 < read_length && 1404 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE) 1405 { 1406 read_length -= keyword_length+2; 1407 1408 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK) 1409 { 1410 Byte profile_header[132]; 1411 Byte local_buffer[PNG_INFLATE_BUF_SIZE]; 1412 png_alloc_size_t size = (sizeof profile_header); 1413 1414 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2); 1415 png_ptr->zstream.avail_in = read_length; 1416 (void)png_inflate_read(png_ptr, local_buffer, 1417 (sizeof local_buffer), &length, profile_header, &size, 1418 0/*finish: don't, because the output is too small*/); 1419 1420 if (size == 0) 1421 { 1422 /* We have the ICC profile header; do the basic header checks. 1423 */ 1424 const png_uint_32 profile_length = 1425 png_get_uint_32(profile_header); 1426 1427 if (png_icc_check_length(png_ptr, &png_ptr->colorspace, 1428 keyword, profile_length)) 1429 { 1430 /* The length is apparently ok, so we can check the 132 1431 * byte header. 1432 */ 1433 if (png_icc_check_header(png_ptr, &png_ptr->colorspace, 1434 keyword, profile_length, profile_header, 1435 png_ptr->color_type)) 1436 { 1437 /* Now read the tag table; a variable size buffer is 1438 * needed at this point, allocate one for the whole 1439 * profile. The header check has already validated 1440 * that none of these stuff will overflow. 1441 */ 1442 const png_uint_32 tag_count = png_get_uint_32( 1443 profile_header+128); 1444 png_bytep profile = png_read_buffer(png_ptr, 1445 profile_length, 2/*silent*/); 1446 1447 if (profile != NULL) 1448 { 1449 memcpy(profile, profile_header, 1450 (sizeof profile_header)); 1451 1452 size = 12 * tag_count; 1453 1454 (void)png_inflate_read(png_ptr, local_buffer, 1455 (sizeof local_buffer), &length, 1456 profile + (sizeof profile_header), &size, 0); 1457 1458 /* Still expect a buffer error because we expect 1459 * there to be some tag data! 1460 */ 1461 if (size == 0) 1462 { 1463 if (png_icc_check_tag_table(png_ptr, 1464 &png_ptr->colorspace, keyword, profile_length, 1465 profile)) 1466 { 1467 /* The profile has been validated for basic 1468 * security issues, so read the whole thing in. 1469 */ 1470 size = profile_length - (sizeof profile_header) 1471 - 12 * tag_count; 1472 1473 (void)png_inflate_read(png_ptr, local_buffer, 1474 (sizeof local_buffer), &length, 1475 profile + (sizeof profile_header) + 1476 12 * tag_count, &size, 1/*finish*/); 1477 1478 if (length > 0 && !(png_ptr->flags & 1479 PNG_FLAG_BENIGN_ERRORS_WARN)) 1480 errmsg = "extra compressed data"; 1481 1482 /* But otherwise allow extra data: */ 1483 else if (size == 0) 1484 { 1485 if (length > 0) 1486 { 1487 /* This can be handled completely, so 1488 * keep going. 1489 */ 1490 png_chunk_warning(png_ptr, 1491 "extra compressed data"); 1492 } 1493 1494 png_crc_finish(png_ptr, length); 1495 finished = 1; 1496 1497 # ifdef PNG_sRGB_SUPPORTED 1498 /* Check for a match against sRGB */ 1499 png_icc_set_sRGB(png_ptr, 1500 &png_ptr->colorspace, profile, 1501 png_ptr->zstream.adler); 1502 # endif 1503 1504 /* Steal the profile for info_ptr. */ 1505 if (info_ptr != NULL) 1506 { 1507 png_free_data(png_ptr, info_ptr, 1508 PNG_FREE_ICCP, 0); 1509 1510 info_ptr->iccp_name = png_voidcast(char*, 1511 png_malloc_base(png_ptr, 1512 keyword_length+1)); 1513 if (info_ptr->iccp_name != NULL) 1514 { 1515 memcpy(info_ptr->iccp_name, keyword, 1516 keyword_length+1); 1517 info_ptr->iccp_proflen = 1518 profile_length; 1519 info_ptr->iccp_profile = profile; 1520 png_ptr->read_buffer = NULL; /*steal*/ 1521 info_ptr->free_me |= PNG_FREE_ICCP; 1522 info_ptr->valid |= PNG_INFO_iCCP; 1523 } 1524 1525 else 1526 { 1527 png_ptr->colorspace.flags |= 1528 PNG_COLORSPACE_INVALID; 1529 errmsg = "out of memory"; 1530 } 1531 } 1532 1533 /* else the profile remains in the read 1534 * buffer which gets reused for subsequent 1535 * chunks. 1536 */ 1537 1538 if (info_ptr != NULL) 1539 png_colorspace_sync(png_ptr, info_ptr); 1540 1541 if (errmsg == NULL) 1542 { 1543 png_ptr->zowner = 0; 1544 return; 1545 } 1546 } 1547 1548 else if (size > 0) 1549 errmsg = "truncated"; 1550 1551 else 1552 errmsg = png_ptr->zstream.msg; 1553 } 1554 1555 /* else png_icc_check_tag_table output an error */ 1556 } 1557 1558 else /* profile truncated */ 1559 errmsg = png_ptr->zstream.msg; 1560 } 1561 1562 else 1563 errmsg = "out of memory"; 1564 } 1565 1566 /* else png_icc_check_header output an error */ 1567 } 1568 1569 /* else png_icc_check_length output an error */ 1570 } 1571 1572 else /* profile truncated */ 1573 errmsg = png_ptr->zstream.msg; 1574 1575 /* Release the stream */ 1576 png_ptr->zowner = 0; 1577 } 1578 1579 else /* png_inflate_claim failed */ 1580 errmsg = png_ptr->zstream.msg; 1581 } 1582 1583 else 1584 errmsg = "bad compression method"; /* or missing */ 1585 } 1586 1587 else 1588 errmsg = "bad keyword"; 1589 } 1590 1591 else 1592 errmsg = "too many profiles"; 1593 1594 /* Failure: the reason is in 'errmsg' */ 1595 if (!finished) 1596 png_crc_finish(png_ptr, length); 1597 1598 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; 1599 png_colorspace_sync(png_ptr, info_ptr); 1600 if (errmsg != NULL) /* else already output */ 1601 png_chunk_benign_error(png_ptr, errmsg); 1602 } 1603 #endif /* PNG_READ_iCCP_SUPPORTED */ 1604 1605 #ifdef PNG_READ_sPLT_SUPPORTED 1606 void /* PRIVATE */ 1607 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1608 /* Note: this does not properly handle chunks that are > 64K under DOS */ 1609 { 1610 png_bytep entry_start, buffer; 1611 png_sPLT_t new_palette; 1612 png_sPLT_entryp pp; 1613 png_uint_32 data_length; 1614 int entry_size, i; 1615 png_uint_32 skip = 0; 1616 png_uint_32 dl; 1617 png_size_t max_dl; 1618 1619 png_debug(1, "in png_handle_sPLT"); 1620 1621 #ifdef PNG_USER_LIMITS_SUPPORTED 1622 if (png_ptr->user_chunk_cache_max != 0) 1623 { 1624 if (png_ptr->user_chunk_cache_max == 1) 1625 { 1626 png_crc_finish(png_ptr, length); 1627 return; 1628 } 1629 1630 if (--png_ptr->user_chunk_cache_max == 1) 1631 { 1632 png_warning(png_ptr, "No space in chunk cache for sPLT"); 1633 png_crc_finish(png_ptr, length); 1634 return; 1635 } 1636 } 1637 #endif 1638 1639 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1640 png_chunk_error(png_ptr, "missing IHDR"); 1641 1642 else if (png_ptr->mode & PNG_HAVE_IDAT) 1643 { 1644 png_crc_finish(png_ptr, length); 1645 png_chunk_benign_error(png_ptr, "out of place"); 1646 return; 1647 } 1648 1649 #ifdef PNG_MAX_MALLOC_64K 1650 if (length > 65535U) 1651 { 1652 png_crc_finish(png_ptr, length); 1653 png_chunk_benign_error(png_ptr, "too large to fit in memory"); 1654 return; 1655 } 1656 #endif 1657 1658 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); 1659 if (buffer == NULL) 1660 { 1661 png_crc_finish(png_ptr, length); 1662 png_chunk_benign_error(png_ptr, "out of memory"); 1663 return; 1664 } 1665 1666 1667 /* WARNING: this may break if size_t is less than 32 bits; it is assumed 1668 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a 1669 * potential breakage point if the types in pngconf.h aren't exactly right. 1670 */ 1671 png_crc_read(png_ptr, buffer, length); 1672 1673 if (png_crc_finish(png_ptr, skip)) 1674 return; 1675 1676 buffer[length] = 0; 1677 1678 for (entry_start = buffer; *entry_start; entry_start++) 1679 /* Empty loop to find end of name */ ; 1680 1681 ++entry_start; 1682 1683 /* A sample depth should follow the separator, and we should be on it */ 1684 if (entry_start > buffer + length - 2) 1685 { 1686 png_warning(png_ptr, "malformed sPLT chunk"); 1687 return; 1688 } 1689 1690 new_palette.depth = *entry_start++; 1691 entry_size = (new_palette.depth == 8 ? 6 : 10); 1692 /* This must fit in a png_uint_32 because it is derived from the original 1693 * chunk data length. 1694 */ 1695 data_length = length - (png_uint_32)(entry_start - buffer); 1696 1697 /* Integrity-check the data length */ 1698 if (data_length % entry_size) 1699 { 1700 png_warning(png_ptr, "sPLT chunk has bad length"); 1701 return; 1702 } 1703 1704 dl = (png_int_32)(data_length / entry_size); 1705 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry)); 1706 1707 if (dl > max_dl) 1708 { 1709 png_warning(png_ptr, "sPLT chunk too long"); 1710 return; 1711 } 1712 1713 new_palette.nentries = (png_int_32)(data_length / entry_size); 1714 1715 new_palette.entries = (png_sPLT_entryp)png_malloc_warn( 1716 png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry))); 1717 1718 if (new_palette.entries == NULL) 1719 { 1720 png_warning(png_ptr, "sPLT chunk requires too much memory"); 1721 return; 1722 } 1723 1724 #ifdef PNG_POINTER_INDEXING_SUPPORTED 1725 for (i = 0; i < new_palette.nentries; i++) 1726 { 1727 pp = new_palette.entries + i; 1728 1729 if (new_palette.depth == 8) 1730 { 1731 pp->red = *entry_start++; 1732 pp->green = *entry_start++; 1733 pp->blue = *entry_start++; 1734 pp->alpha = *entry_start++; 1735 } 1736 1737 else 1738 { 1739 pp->red = png_get_uint_16(entry_start); entry_start += 2; 1740 pp->green = png_get_uint_16(entry_start); entry_start += 2; 1741 pp->blue = png_get_uint_16(entry_start); entry_start += 2; 1742 pp->alpha = png_get_uint_16(entry_start); entry_start += 2; 1743 } 1744 1745 pp->frequency = png_get_uint_16(entry_start); entry_start += 2; 1746 } 1747 #else 1748 pp = new_palette.entries; 1749 1750 for (i = 0; i < new_palette.nentries; i++) 1751 { 1752 1753 if (new_palette.depth == 8) 1754 { 1755 pp[i].red = *entry_start++; 1756 pp[i].green = *entry_start++; 1757 pp[i].blue = *entry_start++; 1758 pp[i].alpha = *entry_start++; 1759 } 1760 1761 else 1762 { 1763 pp[i].red = png_get_uint_16(entry_start); entry_start += 2; 1764 pp[i].green = png_get_uint_16(entry_start); entry_start += 2; 1765 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2; 1766 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2; 1767 } 1768 1769 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2; 1770 } 1771 #endif 1772 1773 /* Discard all chunk data except the name and stash that */ 1774 new_palette.name = (png_charp)buffer; 1775 1776 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1); 1777 1778 png_free(png_ptr, new_palette.entries); 1779 } 1780 #endif /* PNG_READ_sPLT_SUPPORTED */ 1781 1782 #ifdef PNG_READ_tRNS_SUPPORTED 1783 void /* PRIVATE */ 1784 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1785 { 1786 png_byte readbuf[PNG_MAX_PALETTE_LENGTH]; 1787 1788 png_debug(1, "in png_handle_tRNS"); 1789 1790 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1791 png_chunk_error(png_ptr, "missing IHDR"); 1792 1793 else if (png_ptr->mode & PNG_HAVE_IDAT) 1794 { 1795 png_crc_finish(png_ptr, length); 1796 png_chunk_benign_error(png_ptr, "out of place"); 1797 return; 1798 } 1799 1800 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS)) 1801 { 1802 png_crc_finish(png_ptr, length); 1803 png_chunk_benign_error(png_ptr, "duplicate"); 1804 return; 1805 } 1806 1807 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) 1808 { 1809 png_byte buf[2]; 1810 1811 if (length != 2) 1812 { 1813 png_crc_finish(png_ptr, length); 1814 png_chunk_benign_error(png_ptr, "invalid"); 1815 return; 1816 } 1817 1818 png_crc_read(png_ptr, buf, 2); 1819 png_ptr->num_trans = 1; 1820 png_ptr->trans_color.gray = png_get_uint_16(buf); 1821 } 1822 1823 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB) 1824 { 1825 png_byte buf[6]; 1826 1827 if (length != 6) 1828 { 1829 png_crc_finish(png_ptr, length); 1830 png_chunk_benign_error(png_ptr, "invalid"); 1831 return; 1832 } 1833 1834 png_crc_read(png_ptr, buf, length); 1835 png_ptr->num_trans = 1; 1836 png_ptr->trans_color.red = png_get_uint_16(buf); 1837 png_ptr->trans_color.green = png_get_uint_16(buf + 2); 1838 png_ptr->trans_color.blue = png_get_uint_16(buf + 4); 1839 } 1840 1841 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1842 { 1843 if (!(png_ptr->mode & PNG_HAVE_PLTE)) 1844 { 1845 /* TODO: is this actually an error in the ISO spec? */ 1846 png_crc_finish(png_ptr, length); 1847 png_chunk_benign_error(png_ptr, "out of place"); 1848 return; 1849 } 1850 1851 if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH || 1852 length == 0) 1853 { 1854 png_crc_finish(png_ptr, length); 1855 png_chunk_benign_error(png_ptr, "invalid"); 1856 return; 1857 } 1858 1859 png_crc_read(png_ptr, readbuf, length); 1860 png_ptr->num_trans = (png_uint_16)length; 1861 } 1862 1863 else 1864 { 1865 png_crc_finish(png_ptr, length); 1866 png_chunk_benign_error(png_ptr, "invalid with alpha channel"); 1867 return; 1868 } 1869 1870 if (png_crc_finish(png_ptr, 0)) 1871 { 1872 png_ptr->num_trans = 0; 1873 return; 1874 } 1875 1876 /* TODO: this is a horrible side effect in the palette case because the 1877 * png_struct ends up with a pointer to the tRNS buffer owned by the 1878 * png_info. Fix this. 1879 */ 1880 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans, 1881 &(png_ptr->trans_color)); 1882 } 1883 #endif 1884 1885 #ifdef PNG_READ_bKGD_SUPPORTED 1886 void /* PRIVATE */ 1887 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1888 { 1889 unsigned int truelen; 1890 png_byte buf[6]; 1891 png_color_16 background; 1892 1893 png_debug(1, "in png_handle_bKGD"); 1894 1895 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1896 png_chunk_error(png_ptr, "missing IHDR"); 1897 1898 else if ((png_ptr->mode & PNG_HAVE_IDAT) || 1899 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && 1900 !(png_ptr->mode & PNG_HAVE_PLTE))) 1901 { 1902 png_crc_finish(png_ptr, length); 1903 png_chunk_benign_error(png_ptr, "out of place"); 1904 return; 1905 } 1906 1907 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)) 1908 { 1909 png_crc_finish(png_ptr, length); 1910 png_chunk_benign_error(png_ptr, "duplicate"); 1911 return; 1912 } 1913 1914 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1915 truelen = 1; 1916 1917 else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) 1918 truelen = 6; 1919 1920 else 1921 truelen = 2; 1922 1923 if (length != truelen) 1924 { 1925 png_crc_finish(png_ptr, length); 1926 png_chunk_benign_error(png_ptr, "invalid"); 1927 return; 1928 } 1929 1930 png_crc_read(png_ptr, buf, truelen); 1931 1932 if (png_crc_finish(png_ptr, 0)) 1933 return; 1934 1935 /* We convert the index value into RGB components so that we can allow 1936 * arbitrary RGB values for background when we have transparency, and 1937 * so it is easy to determine the RGB values of the background color 1938 * from the info_ptr struct. 1939 */ 1940 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1941 { 1942 background.index = buf[0]; 1943 1944 if (info_ptr && info_ptr->num_palette) 1945 { 1946 if (buf[0] >= info_ptr->num_palette) 1947 { 1948 png_chunk_benign_error(png_ptr, "invalid index"); 1949 return; 1950 } 1951 1952 background.red = (png_uint_16)png_ptr->palette[buf[0]].red; 1953 background.green = (png_uint_16)png_ptr->palette[buf[0]].green; 1954 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue; 1955 } 1956 1957 else 1958 background.red = background.green = background.blue = 0; 1959 1960 background.gray = 0; 1961 } 1962 1963 else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */ 1964 { 1965 background.index = 0; 1966 background.red = 1967 background.green = 1968 background.blue = 1969 background.gray = png_get_uint_16(buf); 1970 } 1971 1972 else 1973 { 1974 background.index = 0; 1975 background.red = png_get_uint_16(buf); 1976 background.green = png_get_uint_16(buf + 2); 1977 background.blue = png_get_uint_16(buf + 4); 1978 background.gray = 0; 1979 } 1980 1981 png_set_bKGD(png_ptr, info_ptr, &background); 1982 } 1983 #endif 1984 1985 #ifdef PNG_READ_hIST_SUPPORTED 1986 void /* PRIVATE */ 1987 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 1988 { 1989 unsigned int num, i; 1990 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH]; 1991 1992 png_debug(1, "in png_handle_hIST"); 1993 1994 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 1995 png_chunk_error(png_ptr, "missing IHDR"); 1996 1997 else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE)) 1998 { 1999 png_crc_finish(png_ptr, length); 2000 png_chunk_benign_error(png_ptr, "out of place"); 2001 return; 2002 } 2003 2004 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST)) 2005 { 2006 png_crc_finish(png_ptr, length); 2007 png_chunk_benign_error(png_ptr, "duplicate"); 2008 return; 2009 } 2010 2011 num = length / 2 ; 2012 2013 if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH) 2014 { 2015 png_crc_finish(png_ptr, length); 2016 png_chunk_benign_error(png_ptr, "invalid"); 2017 return; 2018 } 2019 2020 for (i = 0; i < num; i++) 2021 { 2022 png_byte buf[2]; 2023 2024 png_crc_read(png_ptr, buf, 2); 2025 readbuf[i] = png_get_uint_16(buf); 2026 } 2027 2028 if (png_crc_finish(png_ptr, 0)) 2029 return; 2030 2031 png_set_hIST(png_ptr, info_ptr, readbuf); 2032 } 2033 #endif 2034 2035 #ifdef PNG_READ_pHYs_SUPPORTED 2036 void /* PRIVATE */ 2037 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2038 { 2039 png_byte buf[9]; 2040 png_uint_32 res_x, res_y; 2041 int unit_type; 2042 2043 png_debug(1, "in png_handle_pHYs"); 2044 2045 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2046 png_chunk_error(png_ptr, "missing IHDR"); 2047 2048 else if (png_ptr->mode & PNG_HAVE_IDAT) 2049 { 2050 png_crc_finish(png_ptr, length); 2051 png_chunk_benign_error(png_ptr, "out of place"); 2052 return; 2053 } 2054 2055 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs)) 2056 { 2057 png_crc_finish(png_ptr, length); 2058 png_chunk_benign_error(png_ptr, "duplicate"); 2059 return; 2060 } 2061 2062 if (length != 9) 2063 { 2064 png_crc_finish(png_ptr, length); 2065 png_chunk_benign_error(png_ptr, "invalid"); 2066 return; 2067 } 2068 2069 png_crc_read(png_ptr, buf, 9); 2070 2071 if (png_crc_finish(png_ptr, 0)) 2072 return; 2073 2074 res_x = png_get_uint_32(buf); 2075 res_y = png_get_uint_32(buf + 4); 2076 unit_type = buf[8]; 2077 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type); 2078 } 2079 #endif 2080 2081 #ifdef PNG_READ_oFFs_SUPPORTED 2082 void /* PRIVATE */ 2083 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2084 { 2085 png_byte buf[9]; 2086 png_int_32 offset_x, offset_y; 2087 int unit_type; 2088 2089 png_debug(1, "in png_handle_oFFs"); 2090 2091 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2092 png_chunk_error(png_ptr, "missing IHDR"); 2093 2094 else if (png_ptr->mode & PNG_HAVE_IDAT) 2095 { 2096 png_crc_finish(png_ptr, length); 2097 png_chunk_benign_error(png_ptr, "out of place"); 2098 return; 2099 } 2100 2101 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs)) 2102 { 2103 png_crc_finish(png_ptr, length); 2104 png_chunk_benign_error(png_ptr, "duplicate"); 2105 return; 2106 } 2107 2108 if (length != 9) 2109 { 2110 png_crc_finish(png_ptr, length); 2111 png_chunk_benign_error(png_ptr, "invalid"); 2112 return; 2113 } 2114 2115 png_crc_read(png_ptr, buf, 9); 2116 2117 if (png_crc_finish(png_ptr, 0)) 2118 return; 2119 2120 offset_x = png_get_int_32(buf); 2121 offset_y = png_get_int_32(buf + 4); 2122 unit_type = buf[8]; 2123 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type); 2124 } 2125 #endif 2126 2127 #ifdef PNG_READ_pCAL_SUPPORTED 2128 /* Read the pCAL chunk (described in the PNG Extensions document) */ 2129 void /* PRIVATE */ 2130 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2131 { 2132 png_int_32 X0, X1; 2133 png_byte type, nparams; 2134 png_bytep buffer, buf, units, endptr; 2135 png_charpp params; 2136 int i; 2137 2138 png_debug(1, "in png_handle_pCAL"); 2139 2140 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2141 png_chunk_error(png_ptr, "missing IHDR"); 2142 2143 else if (png_ptr->mode & PNG_HAVE_IDAT) 2144 { 2145 png_crc_finish(png_ptr, length); 2146 png_chunk_benign_error(png_ptr, "out of place"); 2147 return; 2148 } 2149 2150 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL)) 2151 { 2152 png_crc_finish(png_ptr, length); 2153 png_chunk_benign_error(png_ptr, "duplicate"); 2154 return; 2155 } 2156 2157 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)", 2158 length + 1); 2159 2160 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); 2161 2162 if (buffer == NULL) 2163 { 2164 png_crc_finish(png_ptr, length); 2165 png_chunk_benign_error(png_ptr, "out of memory"); 2166 return; 2167 } 2168 2169 png_crc_read(png_ptr, buffer, length); 2170 2171 if (png_crc_finish(png_ptr, 0)) 2172 return; 2173 2174 buffer[length] = 0; /* Null terminate the last string */ 2175 2176 png_debug(3, "Finding end of pCAL purpose string"); 2177 for (buf = buffer; *buf; buf++) 2178 /* Empty loop */ ; 2179 2180 endptr = buffer + length; 2181 2182 /* We need to have at least 12 bytes after the purpose string 2183 * in order to get the parameter information. 2184 */ 2185 if (endptr <= buf + 12) 2186 { 2187 png_chunk_benign_error(png_ptr, "invalid"); 2188 return; 2189 } 2190 2191 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units"); 2192 X0 = png_get_int_32((png_bytep)buf+1); 2193 X1 = png_get_int_32((png_bytep)buf+5); 2194 type = buf[9]; 2195 nparams = buf[10]; 2196 units = buf + 11; 2197 2198 png_debug(3, "Checking pCAL equation type and number of parameters"); 2199 /* Check that we have the right number of parameters for known 2200 * equation types. 2201 */ 2202 if ((type == PNG_EQUATION_LINEAR && nparams != 2) || 2203 (type == PNG_EQUATION_BASE_E && nparams != 3) || 2204 (type == PNG_EQUATION_ARBITRARY && nparams != 3) || 2205 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4)) 2206 { 2207 png_chunk_benign_error(png_ptr, "invalid parameter count"); 2208 return; 2209 } 2210 2211 else if (type >= PNG_EQUATION_LAST) 2212 { 2213 png_chunk_benign_error(png_ptr, "unrecognized equation type"); 2214 } 2215 2216 for (buf = units; *buf; buf++) 2217 /* Empty loop to move past the units string. */ ; 2218 2219 png_debug(3, "Allocating pCAL parameters array"); 2220 2221 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr, 2222 nparams * (sizeof (png_charp)))); 2223 2224 if (params == NULL) 2225 { 2226 png_chunk_benign_error(png_ptr, "out of memory"); 2227 return; 2228 } 2229 2230 /* Get pointers to the start of each parameter string. */ 2231 for (i = 0; i < nparams; i++) 2232 { 2233 buf++; /* Skip the null string terminator from previous parameter. */ 2234 2235 png_debug1(3, "Reading pCAL parameter %d", i); 2236 2237 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++) 2238 /* Empty loop to move past each parameter string */ ; 2239 2240 /* Make sure we haven't run out of data yet */ 2241 if (buf > endptr) 2242 { 2243 png_free(png_ptr, params); 2244 png_chunk_benign_error(png_ptr, "invalid data"); 2245 return; 2246 } 2247 } 2248 2249 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams, 2250 (png_charp)units, params); 2251 2252 png_free(png_ptr, params); 2253 } 2254 #endif 2255 2256 #ifdef PNG_READ_sCAL_SUPPORTED 2257 /* Read the sCAL chunk */ 2258 void /* PRIVATE */ 2259 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2260 { 2261 png_bytep buffer; 2262 png_size_t i; 2263 int state; 2264 2265 png_debug(1, "in png_handle_sCAL"); 2266 2267 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2268 png_chunk_error(png_ptr, "missing IHDR"); 2269 2270 else if (png_ptr->mode & PNG_HAVE_IDAT) 2271 { 2272 png_crc_finish(png_ptr, length); 2273 png_chunk_benign_error(png_ptr, "out of place"); 2274 return; 2275 } 2276 2277 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL)) 2278 { 2279 png_crc_finish(png_ptr, length); 2280 png_chunk_benign_error(png_ptr, "duplicate"); 2281 return; 2282 } 2283 2284 /* Need unit type, width, \0, height: minimum 4 bytes */ 2285 else if (length < 4) 2286 { 2287 png_crc_finish(png_ptr, length); 2288 png_chunk_benign_error(png_ptr, "invalid"); 2289 return; 2290 } 2291 2292 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)", 2293 length + 1); 2294 2295 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); 2296 2297 if (buffer == NULL) 2298 { 2299 png_chunk_benign_error(png_ptr, "out of memory"); 2300 png_crc_finish(png_ptr, length); 2301 return; 2302 } 2303 2304 png_crc_read(png_ptr, buffer, length); 2305 buffer[length] = 0; /* Null terminate the last string */ 2306 2307 if (png_crc_finish(png_ptr, 0)) 2308 return; 2309 2310 /* Validate the unit. */ 2311 if (buffer[0] != 1 && buffer[0] != 2) 2312 { 2313 png_chunk_benign_error(png_ptr, "invalid unit"); 2314 return; 2315 } 2316 2317 /* Validate the ASCII numbers, need two ASCII numbers separated by 2318 * a '\0' and they need to fit exactly in the chunk data. 2319 */ 2320 i = 1; 2321 state = 0; 2322 2323 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) || 2324 i >= length || buffer[i++] != 0) 2325 png_chunk_benign_error(png_ptr, "bad width format"); 2326 2327 else if (!PNG_FP_IS_POSITIVE(state)) 2328 png_chunk_benign_error(png_ptr, "non-positive width"); 2329 2330 else 2331 { 2332 png_size_t heighti = i; 2333 2334 state = 0; 2335 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) || 2336 i != length) 2337 png_chunk_benign_error(png_ptr, "bad height format"); 2338 2339 else if (!PNG_FP_IS_POSITIVE(state)) 2340 png_chunk_benign_error(png_ptr, "non-positive height"); 2341 2342 else 2343 /* This is the (only) success case. */ 2344 png_set_sCAL_s(png_ptr, info_ptr, buffer[0], 2345 (png_charp)buffer+1, (png_charp)buffer+heighti); 2346 } 2347 } 2348 #endif 2349 2350 #ifdef PNG_READ_tIME_SUPPORTED 2351 void /* PRIVATE */ 2352 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2353 { 2354 png_byte buf[7]; 2355 png_time mod_time; 2356 2357 png_debug(1, "in png_handle_tIME"); 2358 2359 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2360 png_chunk_error(png_ptr, "missing IHDR"); 2361 2362 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME)) 2363 { 2364 png_crc_finish(png_ptr, length); 2365 png_chunk_benign_error(png_ptr, "duplicate"); 2366 return; 2367 } 2368 2369 if (png_ptr->mode & PNG_HAVE_IDAT) 2370 png_ptr->mode |= PNG_AFTER_IDAT; 2371 2372 if (length != 7) 2373 { 2374 png_crc_finish(png_ptr, length); 2375 png_chunk_benign_error(png_ptr, "invalid"); 2376 return; 2377 } 2378 2379 png_crc_read(png_ptr, buf, 7); 2380 2381 if (png_crc_finish(png_ptr, 0)) 2382 return; 2383 2384 mod_time.second = buf[6]; 2385 mod_time.minute = buf[5]; 2386 mod_time.hour = buf[4]; 2387 mod_time.day = buf[3]; 2388 mod_time.month = buf[2]; 2389 mod_time.year = png_get_uint_16(buf); 2390 2391 png_set_tIME(png_ptr, info_ptr, &mod_time); 2392 } 2393 #endif 2394 2395 #ifdef PNG_READ_tEXt_SUPPORTED 2396 /* Note: this does not properly handle chunks that are > 64K under DOS */ 2397 void /* PRIVATE */ 2398 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2399 { 2400 png_text text_info; 2401 png_bytep buffer; 2402 png_charp key; 2403 png_charp text; 2404 png_uint_32 skip = 0; 2405 2406 png_debug(1, "in png_handle_tEXt"); 2407 2408 #ifdef PNG_USER_LIMITS_SUPPORTED 2409 if (png_ptr->user_chunk_cache_max != 0) 2410 { 2411 if (png_ptr->user_chunk_cache_max == 1) 2412 { 2413 png_crc_finish(png_ptr, length); 2414 return; 2415 } 2416 2417 if (--png_ptr->user_chunk_cache_max == 1) 2418 { 2419 png_crc_finish(png_ptr, length); 2420 png_chunk_benign_error(png_ptr, "no space in chunk cache"); 2421 return; 2422 } 2423 } 2424 #endif 2425 2426 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2427 png_chunk_error(png_ptr, "missing IHDR"); 2428 2429 if (png_ptr->mode & PNG_HAVE_IDAT) 2430 png_ptr->mode |= PNG_AFTER_IDAT; 2431 2432 #ifdef PNG_MAX_MALLOC_64K 2433 if (length > 65535U) 2434 { 2435 png_crc_finish(png_ptr, length); 2436 png_chunk_benign_error(png_ptr, "too large to fit in memory"); 2437 return; 2438 } 2439 #endif 2440 2441 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/); 2442 2443 if (buffer == NULL) 2444 { 2445 png_chunk_benign_error(png_ptr, "out of memory"); 2446 return; 2447 } 2448 2449 png_crc_read(png_ptr, buffer, length); 2450 2451 if (png_crc_finish(png_ptr, skip)) 2452 return; 2453 2454 key = (png_charp)buffer; 2455 key[length] = 0; 2456 2457 for (text = key; *text; text++) 2458 /* Empty loop to find end of key */ ; 2459 2460 if (text != key + length) 2461 text++; 2462 2463 text_info.compression = PNG_TEXT_COMPRESSION_NONE; 2464 text_info.key = key; 2465 text_info.lang = NULL; 2466 text_info.lang_key = NULL; 2467 text_info.itxt_length = 0; 2468 text_info.text = text; 2469 text_info.text_length = strlen(text); 2470 2471 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1)) 2472 png_warning(png_ptr, "Insufficient memory to process text chunk"); 2473 } 2474 #endif 2475 2476 #ifdef PNG_READ_zTXt_SUPPORTED 2477 /* Note: this does not correctly handle chunks that are > 64K under DOS */ 2478 void /* PRIVATE */ 2479 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2480 { 2481 png_const_charp errmsg = NULL; 2482 png_bytep buffer; 2483 png_uint_32 keyword_length; 2484 2485 png_debug(1, "in png_handle_zTXt"); 2486 2487 #ifdef PNG_USER_LIMITS_SUPPORTED 2488 if (png_ptr->user_chunk_cache_max != 0) 2489 { 2490 if (png_ptr->user_chunk_cache_max == 1) 2491 { 2492 png_crc_finish(png_ptr, length); 2493 return; 2494 } 2495 2496 if (--png_ptr->user_chunk_cache_max == 1) 2497 { 2498 png_crc_finish(png_ptr, length); 2499 png_chunk_benign_error(png_ptr, "no space in chunk cache"); 2500 return; 2501 } 2502 } 2503 #endif 2504 2505 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2506 png_chunk_error(png_ptr, "missing IHDR"); 2507 2508 if (png_ptr->mode & PNG_HAVE_IDAT) 2509 png_ptr->mode |= PNG_AFTER_IDAT; 2510 2511 buffer = png_read_buffer(png_ptr, length, 2/*silent*/); 2512 2513 if (buffer == NULL) 2514 { 2515 png_crc_finish(png_ptr, length); 2516 png_chunk_benign_error(png_ptr, "out of memory"); 2517 return; 2518 } 2519 2520 png_crc_read(png_ptr, buffer, length); 2521 2522 if (png_crc_finish(png_ptr, 0)) 2523 return; 2524 2525 /* TODO: also check that the keyword contents match the spec! */ 2526 for (keyword_length = 0; 2527 keyword_length < length && buffer[keyword_length] != 0; 2528 ++keyword_length) 2529 /* Empty loop to find end of name */ ; 2530 2531 if (keyword_length > 79 || keyword_length < 1) 2532 errmsg = "bad keyword"; 2533 2534 /* zTXt must have some LZ data after the keyword, although it may expand to 2535 * zero bytes; we need a '\0' at the end of the keyword, the compression type 2536 * then the LZ data: 2537 */ 2538 else if (keyword_length + 3 > length) 2539 errmsg = "truncated"; 2540 2541 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE) 2542 errmsg = "unknown compression type"; 2543 2544 else 2545 { 2546 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX; 2547 2548 /* TODO: at present png_decompress_chunk imposes a single application 2549 * level memory limit, this should be split to different values for iCCP 2550 * and text chunks. 2551 */ 2552 if (png_decompress_chunk(png_ptr, length, keyword_length+2, 2553 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END) 2554 { 2555 png_text text; 2556 2557 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except 2558 * for the extra compression type byte and the fact that it isn't 2559 * necessarily '\0' terminated. 2560 */ 2561 buffer = png_ptr->read_buffer; 2562 buffer[uncompressed_length+(keyword_length+2)] = 0; 2563 2564 text.compression = PNG_TEXT_COMPRESSION_zTXt; 2565 text.key = (png_charp)buffer; 2566 text.text = (png_charp)(buffer + keyword_length+2); 2567 text.text_length = uncompressed_length; 2568 text.itxt_length = 0; 2569 text.lang = NULL; 2570 text.lang_key = NULL; 2571 2572 if (png_set_text_2(png_ptr, info_ptr, &text, 1)) 2573 errmsg = "insufficient memory"; 2574 } 2575 2576 else 2577 errmsg = png_ptr->zstream.msg; 2578 } 2579 2580 if (errmsg != NULL) 2581 png_chunk_benign_error(png_ptr, errmsg); 2582 } 2583 #endif 2584 2585 #ifdef PNG_READ_iTXt_SUPPORTED 2586 /* Note: this does not correctly handle chunks that are > 64K under DOS */ 2587 void /* PRIVATE */ 2588 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 2589 { 2590 png_const_charp errmsg = NULL; 2591 png_bytep buffer; 2592 png_uint_32 prefix_length; 2593 2594 png_debug(1, "in png_handle_iTXt"); 2595 2596 #ifdef PNG_USER_LIMITS_SUPPORTED 2597 if (png_ptr->user_chunk_cache_max != 0) 2598 { 2599 if (png_ptr->user_chunk_cache_max == 1) 2600 { 2601 png_crc_finish(png_ptr, length); 2602 return; 2603 } 2604 2605 if (--png_ptr->user_chunk_cache_max == 1) 2606 { 2607 png_crc_finish(png_ptr, length); 2608 png_chunk_benign_error(png_ptr, "no space in chunk cache"); 2609 return; 2610 } 2611 } 2612 #endif 2613 2614 if (!(png_ptr->mode & PNG_HAVE_IHDR)) 2615 png_chunk_error(png_ptr, "missing IHDR"); 2616 2617 if (png_ptr->mode & PNG_HAVE_IDAT) 2618 png_ptr->mode |= PNG_AFTER_IDAT; 2619 2620 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/); 2621 2622 if (buffer == NULL) 2623 { 2624 png_crc_finish(png_ptr, length); 2625 png_chunk_benign_error(png_ptr, "out of memory"); 2626 return; 2627 } 2628 2629 png_crc_read(png_ptr, buffer, length); 2630 2631 if (png_crc_finish(png_ptr, 0)) 2632 return; 2633 2634 /* First the keyword. */ 2635 for (prefix_length=0; 2636 prefix_length < length && buffer[prefix_length] != 0; 2637 ++prefix_length) 2638 /* Empty loop */ ; 2639 2640 /* Perform a basic check on the keyword length here. */ 2641 if (prefix_length > 79 || prefix_length < 1) 2642 errmsg = "bad keyword"; 2643 2644 /* Expect keyword, compression flag, compression type, language, translated 2645 * keyword (both may be empty but are 0 terminated) then the text, which may 2646 * be empty. 2647 */ 2648 else if (prefix_length + 5 > length) 2649 errmsg = "truncated"; 2650 2651 else if (buffer[prefix_length+1] == 0 || 2652 (buffer[prefix_length+1] == 1 && 2653 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE)) 2654 { 2655 int compressed = buffer[prefix_length+1] != 0; 2656 png_uint_32 language_offset, translated_keyword_offset; 2657 png_alloc_size_t uncompressed_length = 0; 2658 2659 /* Now the language tag */ 2660 prefix_length += 3; 2661 language_offset = prefix_length; 2662 2663 for (; prefix_length < length && buffer[prefix_length] != 0; 2664 ++prefix_length) 2665 /* Empty loop */ ; 2666 2667 /* WARNING: the length may be invalid here, this is checked below. */ 2668 translated_keyword_offset = ++prefix_length; 2669 2670 for (; prefix_length < length && buffer[prefix_length] != 0; 2671 ++prefix_length) 2672 /* Empty loop */ ; 2673 2674 /* prefix_length should now be at the trailing '\0' of the translated 2675 * keyword, but it may already be over the end. None of this arithmetic 2676 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit 2677 * systems the available allocaton may overflow. 2678 */ 2679 ++prefix_length; 2680 2681 if (!compressed && prefix_length <= length) 2682 uncompressed_length = length - prefix_length; 2683 2684 else if (compressed && prefix_length < length) 2685 { 2686 uncompressed_length = PNG_SIZE_MAX; 2687 2688 /* TODO: at present png_decompress_chunk imposes a single application 2689 * level memory limit, this should be split to different values for 2690 * iCCP and text chunks. 2691 */ 2692 if (png_decompress_chunk(png_ptr, length, prefix_length, 2693 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END) 2694 buffer = png_ptr->read_buffer; 2695 2696 else 2697 errmsg = png_ptr->zstream.msg; 2698 } 2699 2700 else 2701 errmsg = "truncated"; 2702 2703 if (errmsg == NULL) 2704 { 2705 png_text text; 2706 2707 buffer[uncompressed_length+prefix_length] = 0; 2708 2709 if (compressed) 2710 text.compression = PNG_ITXT_COMPRESSION_NONE; 2711 2712 else 2713 text.compression = PNG_ITXT_COMPRESSION_zTXt; 2714 2715 text.key = (png_charp)buffer; 2716 text.lang = (png_charp)buffer + language_offset; 2717 text.lang_key = (png_charp)buffer + translated_keyword_offset; 2718 text.text = (png_charp)buffer + prefix_length; 2719 text.text_length = 0; 2720 text.itxt_length = uncompressed_length; 2721 2722 if (png_set_text_2(png_ptr, info_ptr, &text, 1)) 2723 errmsg = "insufficient memory"; 2724 } 2725 } 2726 2727 else 2728 errmsg = "bad compression info"; 2729 2730 if (errmsg != NULL) 2731 png_chunk_benign_error(png_ptr, errmsg); 2732 } 2733 #endif 2734 2735 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED 2736 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */ 2737 static int 2738 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length) 2739 { 2740 png_alloc_size_t limit = PNG_SIZE_MAX; 2741 2742 if (png_ptr->unknown_chunk.data != NULL) 2743 { 2744 png_free(png_ptr, png_ptr->unknown_chunk.data); 2745 png_ptr->unknown_chunk.data = NULL; 2746 } 2747 2748 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED 2749 if (png_ptr->user_chunk_malloc_max > 0 && 2750 png_ptr->user_chunk_malloc_max < limit) 2751 limit = png_ptr->user_chunk_malloc_max; 2752 2753 # elif PNG_USER_CHUNK_MALLOC_MAX > 0 2754 if (PNG_USER_CHUNK_MALLOC_MAX < limit) 2755 limit = PNG_USER_CHUNK_MALLOC_MAX; 2756 # endif 2757 2758 if (length <= limit) 2759 { 2760 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name); 2761 /* The following is safe because of the PNG_SIZE_MAX init above */ 2762 png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/; 2763 /* 'mode' is a flag array, only the bottom four bits matter here */ 2764 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/; 2765 2766 if (length == 0) 2767 png_ptr->unknown_chunk.data = NULL; 2768 2769 else 2770 { 2771 /* Do a 'warn' here - it is handled below. */ 2772 png_ptr->unknown_chunk.data = png_voidcast(png_bytep, 2773 png_malloc_warn(png_ptr, length)); 2774 } 2775 } 2776 2777 if (png_ptr->unknown_chunk.data == NULL && length > 0) 2778 { 2779 /* This is benign because we clean up correctly */ 2780 png_crc_finish(png_ptr, length); 2781 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits"); 2782 return 0; 2783 } 2784 2785 else 2786 { 2787 if (length > 0) 2788 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length); 2789 png_crc_finish(png_ptr, 0); 2790 return 1; 2791 } 2792 } 2793 #endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */ 2794 2795 /* Handle an unknown, or known but disabled, chunk */ 2796 void /* PRIVATE */ 2797 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, 2798 png_uint_32 length, int keep) 2799 { 2800 int handled = 0; /* the chunk was handled */ 2801 2802 png_debug(1, "in png_handle_unknown"); 2803 2804 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED 2805 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing 2806 * the bug which meant that setting a non-default behavior for a specific 2807 * chunk would be ignored (the default was always used unless a user 2808 * callback was installed). 2809 * 2810 * 'keep' is the value from the png_chunk_unknown_handling, the setting for 2811 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it 2812 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here. 2813 * This is just an optimization to avoid multiple calls to the lookup 2814 * function. 2815 */ 2816 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 2817 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED 2818 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name); 2819 # endif 2820 # endif 2821 2822 /* One of the following methods will read the chunk or skip it (at least one 2823 * of these is always defined because this is the only way to switch on 2824 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) 2825 */ 2826 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED 2827 /* The user callback takes precedence over the chunk keep value, but the 2828 * keep value is still required to validate a save of a critical chunk. 2829 */ 2830 if (png_ptr->read_user_chunk_fn != NULL) 2831 { 2832 if (png_cache_unknown_chunk(png_ptr, length)) 2833 { 2834 /* Callback to user unknown chunk handler */ 2835 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr, 2836 &png_ptr->unknown_chunk); 2837 2838 /* ret is: 2839 * negative: An error occured, png_chunk_error will be called. 2840 * zero: The chunk was not handled, the chunk will be discarded 2841 * unless png_set_keep_unknown_chunks has been used to set 2842 * a 'keep' behavior for this particular chunk, in which 2843 * case that will be used. A critical chunk will cause an 2844 * error at this point unless it is to be saved. 2845 * positive: The chunk was handled, libpng will ignore/discard it. 2846 */ 2847 if (ret < 0) 2848 png_chunk_error(png_ptr, "error in user chunk"); 2849 2850 else if (ret == 0) 2851 { 2852 /* If the keep value is 'default' or 'never' override it, but 2853 * still error out on critical chunks unless the keep value is 2854 * 'always' While this is weird it is the behavior in 1.4.12. 2855 * A possible improvement would be to obey the value set for the 2856 * chunk, but this would be an API change that would probably 2857 * damage some applications. 2858 * 2859 * The png_app_warning below catches the case that matters, where 2860 * the application has not set specific save or ignore for this 2861 * chunk or global save or ignore. 2862 */ 2863 if (keep < PNG_HANDLE_CHUNK_IF_SAFE) 2864 { 2865 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED 2866 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE) 2867 { 2868 png_chunk_warning(png_ptr, "Saving unknown chunk:"); 2869 png_app_warning(png_ptr, 2870 "forcing save of an unhandled chunk;" 2871 " please call png_set_keep_unknown_chunks"); 2872 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */ 2873 } 2874 # endif 2875 keep = PNG_HANDLE_CHUNK_IF_SAFE; 2876 } 2877 } 2878 2879 else /* chunk was handled */ 2880 { 2881 handled = 1; 2882 /* Critical chunks can be safely discarded at this point. */ 2883 keep = PNG_HANDLE_CHUNK_NEVER; 2884 } 2885 } 2886 2887 else 2888 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */ 2889 } 2890 2891 else 2892 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */ 2893 # endif /* PNG_READ_USER_CHUNKS_SUPPORTED */ 2894 2895 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED 2896 { 2897 /* keep is currently just the per-chunk setting, if there was no 2898 * setting change it to the global default now (not that this may 2899 * still be AS_DEFAULT) then obtain the cache of the chunk if required, 2900 * if not simply skip the chunk. 2901 */ 2902 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT) 2903 keep = png_ptr->unknown_default; 2904 2905 if (keep == PNG_HANDLE_CHUNK_ALWAYS || 2906 (keep == PNG_HANDLE_CHUNK_IF_SAFE && 2907 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))) 2908 { 2909 if (!png_cache_unknown_chunk(png_ptr, length)) 2910 keep = PNG_HANDLE_CHUNK_NEVER; 2911 } 2912 2913 else 2914 png_crc_finish(png_ptr, length); 2915 } 2916 # else 2917 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED 2918 # error no method to support READ_UNKNOWN_CHUNKS 2919 # endif 2920 2921 { 2922 /* If here there is no read callback pointer set and no support is 2923 * compiled in to just save the unknown chunks, so simply skip this 2924 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then 2925 * the app has erroneously asked for unknown chunk saving when there 2926 * is no support. 2927 */ 2928 if (keep > PNG_HANDLE_CHUNK_NEVER) 2929 png_app_error(png_ptr, "no unknown chunk support available"); 2930 2931 png_crc_finish(png_ptr, length); 2932 } 2933 # endif 2934 2935 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED 2936 /* Now store the chunk in the chunk list if appropriate, and if the limits 2937 * permit it. 2938 */ 2939 if (keep == PNG_HANDLE_CHUNK_ALWAYS || 2940 (keep == PNG_HANDLE_CHUNK_IF_SAFE && 2941 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))) 2942 { 2943 # ifdef PNG_USER_LIMITS_SUPPORTED 2944 switch (png_ptr->user_chunk_cache_max) 2945 { 2946 case 2: 2947 png_ptr->user_chunk_cache_max = 1; 2948 png_chunk_benign_error(png_ptr, "no space in chunk cache"); 2949 /* FALL THROUGH */ 2950 case 1: 2951 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical 2952 * chunk being skipped, now there will be a hard error below. 2953 */ 2954 break; 2955 2956 default: /* not at limit */ 2957 --(png_ptr->user_chunk_cache_max); 2958 /* FALL THROUGH */ 2959 case 0: /* no limit */ 2960 # endif /* PNG_USER_LIMITS_SUPPORTED */ 2961 /* Here when the limit isn't reached or when limits are compiled 2962 * out; store the chunk. 2963 */ 2964 png_set_unknown_chunks(png_ptr, info_ptr, 2965 &png_ptr->unknown_chunk, 1); 2966 handled = 1; 2967 # ifdef PNG_USER_LIMITS_SUPPORTED 2968 break; 2969 } 2970 # endif 2971 } 2972 # else /* no store support: the chunk must be handled by the user callback */ 2973 PNG_UNUSED(info_ptr) 2974 # endif 2975 2976 /* Regardless of the error handling below the cached data (if any) can be 2977 * freed now. Notice that the data is not freed if there is a png_error, but 2978 * it will be freed by destroy_read_struct. 2979 */ 2980 if (png_ptr->unknown_chunk.data != NULL) 2981 png_free(png_ptr, png_ptr->unknown_chunk.data); 2982 png_ptr->unknown_chunk.data = NULL; 2983 2984 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */ 2985 /* There is no support to read an unknown chunk, so just skip it. */ 2986 png_crc_finish(png_ptr, length); 2987 PNG_UNUSED(info_ptr) 2988 PNG_UNUSED(keep) 2989 #endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */ 2990 2991 /* Check for unhandled critical chunks */ 2992 if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name)) 2993 png_chunk_error(png_ptr, "unhandled critical chunk"); 2994 } 2995 2996 /* This function is called to verify that a chunk name is valid. 2997 * This function can't have the "critical chunk check" incorporated 2998 * into it, since in the future we will need to be able to call user 2999 * functions to handle unknown critical chunks after we check that 3000 * the chunk name itself is valid. 3001 */ 3002 3003 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is: 3004 * 3005 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97)) 3006 */ 3007 3008 void /* PRIVATE */ 3009 png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name) 3010 { 3011 int i; 3012 3013 png_debug(1, "in png_check_chunk_name"); 3014 3015 for (i=1; i<=4; ++i) 3016 { 3017 int c = chunk_name & 0xff; 3018 3019 if (c < 65 || c > 122 || (c > 90 && c < 97)) 3020 png_chunk_error(png_ptr, "invalid chunk type"); 3021 3022 chunk_name >>= 8; 3023 } 3024 } 3025 3026 /* Combines the row recently read in with the existing pixels in the row. This 3027 * routine takes care of alpha and transparency if requested. This routine also 3028 * handles the two methods of progressive display of interlaced images, 3029 * depending on the 'display' value; if 'display' is true then the whole row 3030 * (dp) is filled from the start by replicating the available pixels. If 3031 * 'display' is false only those pixels present in the pass are filled in. 3032 */ 3033 void /* PRIVATE */ 3034 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display) 3035 { 3036 unsigned int pixel_depth = png_ptr->transformed_pixel_depth; 3037 png_const_bytep sp = png_ptr->row_buf + 1; 3038 png_alloc_size_t row_width = png_ptr->width; 3039 unsigned int pass = png_ptr->pass; 3040 png_bytep end_ptr = 0; 3041 png_byte end_byte = 0; 3042 unsigned int end_mask; 3043 3044 png_debug(1, "in png_combine_row"); 3045 3046 /* Added in 1.5.6: it should not be possible to enter this routine until at 3047 * least one row has been read from the PNG data and transformed. 3048 */ 3049 if (pixel_depth == 0) 3050 png_error(png_ptr, "internal row logic error"); 3051 3052 /* Added in 1.5.4: the pixel depth should match the information returned by 3053 * any call to png_read_update_info at this point. Do not continue if we got 3054 * this wrong. 3055 */ 3056 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes != 3057 PNG_ROWBYTES(pixel_depth, row_width)) 3058 png_error(png_ptr, "internal row size calculation error"); 3059 3060 /* Don't expect this to ever happen: */ 3061 if (row_width == 0) 3062 png_error(png_ptr, "internal row width error"); 3063 3064 /* Preserve the last byte in cases where only part of it will be overwritten, 3065 * the multiply below may overflow, we don't care because ANSI-C guarantees 3066 * we get the low bits. 3067 */ 3068 end_mask = (pixel_depth * row_width) & 7; 3069 if (end_mask != 0) 3070 { 3071 /* end_ptr == NULL is a flag to say do nothing */ 3072 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1; 3073 end_byte = *end_ptr; 3074 # ifdef PNG_READ_PACKSWAP_SUPPORTED 3075 if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */ 3076 end_mask = 0xff << end_mask; 3077 3078 else /* big-endian byte */ 3079 # endif 3080 end_mask = 0xff >> end_mask; 3081 /* end_mask is now the bits to *keep* from the destination row */ 3082 } 3083 3084 /* For non-interlaced images this reduces to a memcpy(). A memcpy() 3085 * will also happen if interlacing isn't supported or if the application 3086 * does not call png_set_interlace_handling(). In the latter cases the 3087 * caller just gets a sequence of the unexpanded rows from each interlace 3088 * pass. 3089 */ 3090 #ifdef PNG_READ_INTERLACING_SUPPORTED 3091 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) && 3092 pass < 6 && (display == 0 || 3093 /* The following copies everything for 'display' on passes 0, 2 and 4. */ 3094 (display == 1 && (pass & 1) != 0))) 3095 { 3096 /* Narrow images may have no bits in a pass; the caller should handle 3097 * this, but this test is cheap: 3098 */ 3099 if (row_width <= PNG_PASS_START_COL(pass)) 3100 return; 3101 3102 if (pixel_depth < 8) 3103 { 3104 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit 3105 * into 32 bits, then a single loop over the bytes using the four byte 3106 * values in the 32-bit mask can be used. For the 'display' option the 3107 * expanded mask may also not require any masking within a byte. To 3108 * make this work the PACKSWAP option must be taken into account - it 3109 * simply requires the pixels to be reversed in each byte. 3110 * 3111 * The 'regular' case requires a mask for each of the first 6 passes, 3112 * the 'display' case does a copy for the even passes in the range 3113 * 0..6. This has already been handled in the test above. 3114 * 3115 * The masks are arranged as four bytes with the first byte to use in 3116 * the lowest bits (little-endian) regardless of the order (PACKSWAP or 3117 * not) of the pixels in each byte. 3118 * 3119 * NOTE: the whole of this logic depends on the caller of this function 3120 * only calling it on rows appropriate to the pass. This function only 3121 * understands the 'x' logic; the 'y' logic is handled by the caller. 3122 * 3123 * The following defines allow generation of compile time constant bit 3124 * masks for each pixel depth and each possibility of swapped or not 3125 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index, 3126 * is in the range 0..7; and the result is 1 if the pixel is to be 3127 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B' 3128 * for the block method. 3129 * 3130 * With some compilers a compile time expression of the general form: 3131 * 3132 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift) 3133 * 3134 * Produces warnings with values of 'shift' in the range 33 to 63 3135 * because the right hand side of the ?: expression is evaluated by 3136 * the compiler even though it isn't used. Microsoft Visual C (various 3137 * versions) and the Intel C compiler are known to do this. To avoid 3138 * this the following macros are used in 1.5.6. This is a temporary 3139 * solution to avoid destabilizing the code during the release process. 3140 */ 3141 # if PNG_USE_COMPILE_TIME_MASKS 3142 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f)) 3143 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f)) 3144 # else 3145 # define PNG_LSR(x,s) ((x)>>(s)) 3146 # define PNG_LSL(x,s) ((x)<<(s)) 3147 # endif 3148 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\ 3149 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1) 3150 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\ 3151 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1) 3152 3153 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is 3154 * little endian - the first pixel is at bit 0 - however the extra 3155 * parameter 's' can be set to cause the mask position to be swapped 3156 * within each byte, to match the PNG format. This is done by XOR of 3157 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4. 3158 */ 3159 # define PIXEL_MASK(p,x,d,s) \ 3160 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0)))) 3161 3162 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask. 3163 */ 3164 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0) 3165 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0) 3166 3167 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp 3168 * cases the result needs replicating, for the 4-bpp case the above 3169 * generates a full 32 bits. 3170 */ 3171 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1))) 3172 3173 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\ 3174 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\ 3175 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d) 3176 3177 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\ 3178 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\ 3179 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d) 3180 3181 #if PNG_USE_COMPILE_TIME_MASKS 3182 /* Utility macros to construct all the masks for a depth/swap 3183 * combination. The 's' parameter says whether the format is PNG 3184 * (big endian bytes) or not. Only the three odd-numbered passes are 3185 * required for the display/block algorithm. 3186 */ 3187 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\ 3188 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) } 3189 3190 # define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) } 3191 3192 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2)) 3193 3194 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and 3195 * then pass: 3196 */ 3197 static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] = 3198 { 3199 /* Little-endian byte masks for PACKSWAP */ 3200 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) }, 3201 /* Normal (big-endian byte) masks - PNG format */ 3202 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) } 3203 }; 3204 3205 /* display_mask has only three entries for the odd passes, so index by 3206 * pass>>1. 3207 */ 3208 static PNG_CONST png_uint_32 display_mask[2][3][3] = 3209 { 3210 /* Little-endian byte masks for PACKSWAP */ 3211 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) }, 3212 /* Normal (big-endian byte) masks - PNG format */ 3213 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) } 3214 }; 3215 3216 # define MASK(pass,depth,display,png)\ 3217 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\ 3218 row_mask[png][DEPTH_INDEX(depth)][pass]) 3219 3220 #else /* !PNG_USE_COMPILE_TIME_MASKS */ 3221 /* This is the runtime alternative: it seems unlikely that this will 3222 * ever be either smaller or faster than the compile time approach. 3223 */ 3224 # define MASK(pass,depth,display,png)\ 3225 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png)) 3226 #endif /* !PNG_USE_COMPILE_TIME_MASKS */ 3227 3228 /* Use the appropriate mask to copy the required bits. In some cases 3229 * the byte mask will be 0 or 0xff, optimize these cases. row_width is 3230 * the number of pixels, but the code copies bytes, so it is necessary 3231 * to special case the end. 3232 */ 3233 png_uint_32 pixels_per_byte = 8 / pixel_depth; 3234 png_uint_32 mask; 3235 3236 # ifdef PNG_READ_PACKSWAP_SUPPORTED 3237 if (png_ptr->transformations & PNG_PACKSWAP) 3238 mask = MASK(pass, pixel_depth, display, 0); 3239 3240 else 3241 # endif 3242 mask = MASK(pass, pixel_depth, display, 1); 3243 3244 for (;;) 3245 { 3246 png_uint_32 m; 3247 3248 /* It doesn't matter in the following if png_uint_32 has more than 3249 * 32 bits because the high bits always match those in m<<24; it is, 3250 * however, essential to use OR here, not +, because of this. 3251 */ 3252 m = mask; 3253 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */ 3254 m &= 0xff; 3255 3256 if (m != 0) /* something to copy */ 3257 { 3258 if (m != 0xff) 3259 *dp = (png_byte)((*dp & ~m) | (*sp & m)); 3260 else 3261 *dp = *sp; 3262 } 3263 3264 /* NOTE: this may overwrite the last byte with garbage if the image 3265 * is not an exact number of bytes wide; libpng has always done 3266 * this. 3267 */ 3268 if (row_width <= pixels_per_byte) 3269 break; /* May need to restore part of the last byte */ 3270 3271 row_width -= pixels_per_byte; 3272 ++dp; 3273 ++sp; 3274 } 3275 } 3276 3277 else /* pixel_depth >= 8 */ 3278 { 3279 unsigned int bytes_to_copy, bytes_to_jump; 3280 3281 /* Validate the depth - it must be a multiple of 8 */ 3282 if (pixel_depth & 7) 3283 png_error(png_ptr, "invalid user transform pixel depth"); 3284 3285 pixel_depth >>= 3; /* now in bytes */ 3286 row_width *= pixel_depth; 3287 3288 /* Regardless of pass number the Adam 7 interlace always results in a 3289 * fixed number of pixels to copy then to skip. There may be a 3290 * different number of pixels to skip at the start though. 3291 */ 3292 { 3293 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth; 3294 3295 row_width -= offset; 3296 dp += offset; 3297 sp += offset; 3298 } 3299 3300 /* Work out the bytes to copy. */ 3301 if (display) 3302 { 3303 /* When doing the 'block' algorithm the pixel in the pass gets 3304 * replicated to adjacent pixels. This is why the even (0,2,4,6) 3305 * passes are skipped above - the entire expanded row is copied. 3306 */ 3307 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth; 3308 3309 /* But don't allow this number to exceed the actual row width. */ 3310 if (bytes_to_copy > row_width) 3311 bytes_to_copy = (unsigned int)/*SAFE*/row_width; 3312 } 3313 3314 else /* normal row; Adam7 only ever gives us one pixel to copy. */ 3315 bytes_to_copy = pixel_depth; 3316 3317 /* In Adam7 there is a constant offset between where the pixels go. */ 3318 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth; 3319 3320 /* And simply copy these bytes. Some optimization is possible here, 3321 * depending on the value of 'bytes_to_copy'. Special case the low 3322 * byte counts, which we know to be frequent. 3323 * 3324 * Notice that these cases all 'return' rather than 'break' - this 3325 * avoids an unnecessary test on whether to restore the last byte 3326 * below. 3327 */ 3328 switch (bytes_to_copy) 3329 { 3330 case 1: 3331 for (;;) 3332 { 3333 *dp = *sp; 3334 3335 if (row_width <= bytes_to_jump) 3336 return; 3337 3338 dp += bytes_to_jump; 3339 sp += bytes_to_jump; 3340 row_width -= bytes_to_jump; 3341 } 3342 3343 case 2: 3344 /* There is a possibility of a partial copy at the end here; this 3345 * slows the code down somewhat. 3346 */ 3347 do 3348 { 3349 dp[0] = sp[0], dp[1] = sp[1]; 3350 3351 if (row_width <= bytes_to_jump) 3352 return; 3353 3354 sp += bytes_to_jump; 3355 dp += bytes_to_jump; 3356 row_width -= bytes_to_jump; 3357 } 3358 while (row_width > 1); 3359 3360 /* And there can only be one byte left at this point: */ 3361 *dp = *sp; 3362 return; 3363 3364 case 3: 3365 /* This can only be the RGB case, so each copy is exactly one 3366 * pixel and it is not necessary to check for a partial copy. 3367 */ 3368 for(;;) 3369 { 3370 dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2]; 3371 3372 if (row_width <= bytes_to_jump) 3373 return; 3374 3375 sp += bytes_to_jump; 3376 dp += bytes_to_jump; 3377 row_width -= bytes_to_jump; 3378 } 3379 3380 default: 3381 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE 3382 /* Check for double byte alignment and, if possible, use a 3383 * 16-bit copy. Don't attempt this for narrow images - ones that 3384 * are less than an interlace panel wide. Don't attempt it for 3385 * wide bytes_to_copy either - use the memcpy there. 3386 */ 3387 if (bytes_to_copy < 16 /*else use memcpy*/ && 3388 png_isaligned(dp, png_uint_16) && 3389 png_isaligned(sp, png_uint_16) && 3390 bytes_to_copy % (sizeof (png_uint_16)) == 0 && 3391 bytes_to_jump % (sizeof (png_uint_16)) == 0) 3392 { 3393 /* Everything is aligned for png_uint_16 copies, but try for 3394 * png_uint_32 first. 3395 */ 3396 if (png_isaligned(dp, png_uint_32) && 3397 png_isaligned(sp, png_uint_32) && 3398 bytes_to_copy % (sizeof (png_uint_32)) == 0 && 3399 bytes_to_jump % (sizeof (png_uint_32)) == 0) 3400 { 3401 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp); 3402 png_const_uint_32p sp32 = png_aligncastconst( 3403 png_const_uint_32p, sp); 3404 size_t skip = (bytes_to_jump-bytes_to_copy) / 3405 (sizeof (png_uint_32)); 3406 3407 do 3408 { 3409 size_t c = bytes_to_copy; 3410 do 3411 { 3412 *dp32++ = *sp32++; 3413 c -= (sizeof (png_uint_32)); 3414 } 3415 while (c > 0); 3416 3417 if (row_width <= bytes_to_jump) 3418 return; 3419 3420 dp32 += skip; 3421 sp32 += skip; 3422 row_width -= bytes_to_jump; 3423 } 3424 while (bytes_to_copy <= row_width); 3425 3426 /* Get to here when the row_width truncates the final copy. 3427 * There will be 1-3 bytes left to copy, so don't try the 3428 * 16-bit loop below. 3429 */ 3430 dp = (png_bytep)dp32; 3431 sp = (png_const_bytep)sp32; 3432 do 3433 *dp++ = *sp++; 3434 while (--row_width > 0); 3435 return; 3436 } 3437 3438 /* Else do it in 16-bit quantities, but only if the size is 3439 * not too large. 3440 */ 3441 else 3442 { 3443 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp); 3444 png_const_uint_16p sp16 = png_aligncastconst( 3445 png_const_uint_16p, sp); 3446 size_t skip = (bytes_to_jump-bytes_to_copy) / 3447 (sizeof (png_uint_16)); 3448 3449 do 3450 { 3451 size_t c = bytes_to_copy; 3452 do 3453 { 3454 *dp16++ = *sp16++; 3455 c -= (sizeof (png_uint_16)); 3456 } 3457 while (c > 0); 3458 3459 if (row_width <= bytes_to_jump) 3460 return; 3461 3462 dp16 += skip; 3463 sp16 += skip; 3464 row_width -= bytes_to_jump; 3465 } 3466 while (bytes_to_copy <= row_width); 3467 3468 /* End of row - 1 byte left, bytes_to_copy > row_width: */ 3469 dp = (png_bytep)dp16; 3470 sp = (png_const_bytep)sp16; 3471 do 3472 *dp++ = *sp++; 3473 while (--row_width > 0); 3474 return; 3475 } 3476 } 3477 #endif /* PNG_ALIGN_ code */ 3478 3479 /* The true default - use a memcpy: */ 3480 for (;;) 3481 { 3482 memcpy(dp, sp, bytes_to_copy); 3483 3484 if (row_width <= bytes_to_jump) 3485 return; 3486 3487 sp += bytes_to_jump; 3488 dp += bytes_to_jump; 3489 row_width -= bytes_to_jump; 3490 if (bytes_to_copy > row_width) 3491 bytes_to_copy = (unsigned int)/*SAFE*/row_width; 3492 } 3493 } 3494 3495 /* NOT REACHED*/ 3496 } /* pixel_depth >= 8 */ 3497 3498 /* Here if pixel_depth < 8 to check 'end_ptr' below. */ 3499 } 3500 else 3501 #endif 3502 3503 /* If here then the switch above wasn't used so just memcpy the whole row 3504 * from the temporary row buffer (notice that this overwrites the end of the 3505 * destination row if it is a partial byte.) 3506 */ 3507 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width)); 3508 3509 /* Restore the overwritten bits from the last byte if necessary. */ 3510 if (end_ptr != NULL) 3511 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask)); 3512 } 3513 3514 #ifdef PNG_READ_INTERLACING_SUPPORTED 3515 void /* PRIVATE */ 3516 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass, 3517 png_uint_32 transformations /* Because these may affect the byte layout */) 3518 { 3519 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 3520 /* Offset to next interlace block */ 3521 static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 3522 3523 png_debug(1, "in png_do_read_interlace"); 3524 if (row != NULL && row_info != NULL) 3525 { 3526 png_uint_32 final_width; 3527 3528 final_width = row_info->width * png_pass_inc[pass]; 3529 3530 switch (row_info->pixel_depth) 3531 { 3532 case 1: 3533 { 3534 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3); 3535 png_bytep dp = row + (png_size_t)((final_width - 1) >> 3); 3536 int sshift, dshift; 3537 int s_start, s_end, s_inc; 3538 int jstop = png_pass_inc[pass]; 3539 png_byte v; 3540 png_uint_32 i; 3541 int j; 3542 3543 #ifdef PNG_READ_PACKSWAP_SUPPORTED 3544 if (transformations & PNG_PACKSWAP) 3545 { 3546 sshift = (int)((row_info->width + 7) & 0x07); 3547 dshift = (int)((final_width + 7) & 0x07); 3548 s_start = 7; 3549 s_end = 0; 3550 s_inc = -1; 3551 } 3552 3553 else 3554 #endif 3555 { 3556 sshift = 7 - (int)((row_info->width + 7) & 0x07); 3557 dshift = 7 - (int)((final_width + 7) & 0x07); 3558 s_start = 0; 3559 s_end = 7; 3560 s_inc = 1; 3561 } 3562 3563 for (i = 0; i < row_info->width; i++) 3564 { 3565 v = (png_byte)((*sp >> sshift) & 0x01); 3566 for (j = 0; j < jstop; j++) 3567 { 3568 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift)); 3569 tmp |= v << dshift; 3570 *dp = (png_byte)(tmp & 0xff); 3571 3572 if (dshift == s_end) 3573 { 3574 dshift = s_start; 3575 dp--; 3576 } 3577 3578 else 3579 dshift += s_inc; 3580 } 3581 3582 if (sshift == s_end) 3583 { 3584 sshift = s_start; 3585 sp--; 3586 } 3587 3588 else 3589 sshift += s_inc; 3590 } 3591 break; 3592 } 3593 3594 case 2: 3595 { 3596 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2); 3597 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2); 3598 int sshift, dshift; 3599 int s_start, s_end, s_inc; 3600 int jstop = png_pass_inc[pass]; 3601 png_uint_32 i; 3602 3603 #ifdef PNG_READ_PACKSWAP_SUPPORTED 3604 if (transformations & PNG_PACKSWAP) 3605 { 3606 sshift = (int)(((row_info->width + 3) & 0x03) << 1); 3607 dshift = (int)(((final_width + 3) & 0x03) << 1); 3608 s_start = 6; 3609 s_end = 0; 3610 s_inc = -2; 3611 } 3612 3613 else 3614 #endif 3615 { 3616 sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1); 3617 dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1); 3618 s_start = 0; 3619 s_end = 6; 3620 s_inc = 2; 3621 } 3622 3623 for (i = 0; i < row_info->width; i++) 3624 { 3625 png_byte v; 3626 int j; 3627 3628 v = (png_byte)((*sp >> sshift) & 0x03); 3629 for (j = 0; j < jstop; j++) 3630 { 3631 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift)); 3632 tmp |= v << dshift; 3633 *dp = (png_byte)(tmp & 0xff); 3634 3635 if (dshift == s_end) 3636 { 3637 dshift = s_start; 3638 dp--; 3639 } 3640 3641 else 3642 dshift += s_inc; 3643 } 3644 3645 if (sshift == s_end) 3646 { 3647 sshift = s_start; 3648 sp--; 3649 } 3650 3651 else 3652 sshift += s_inc; 3653 } 3654 break; 3655 } 3656 3657 case 4: 3658 { 3659 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1); 3660 png_bytep dp = row + (png_size_t)((final_width - 1) >> 1); 3661 int sshift, dshift; 3662 int s_start, s_end, s_inc; 3663 png_uint_32 i; 3664 int jstop = png_pass_inc[pass]; 3665 3666 #ifdef PNG_READ_PACKSWAP_SUPPORTED 3667 if (transformations & PNG_PACKSWAP) 3668 { 3669 sshift = (int)(((row_info->width + 1) & 0x01) << 2); 3670 dshift = (int)(((final_width + 1) & 0x01) << 2); 3671 s_start = 4; 3672 s_end = 0; 3673 s_inc = -4; 3674 } 3675 3676 else 3677 #endif 3678 { 3679 sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2); 3680 dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2); 3681 s_start = 0; 3682 s_end = 4; 3683 s_inc = 4; 3684 } 3685 3686 for (i = 0; i < row_info->width; i++) 3687 { 3688 png_byte v = (png_byte)((*sp >> sshift) & 0x0f); 3689 int j; 3690 3691 for (j = 0; j < jstop; j++) 3692 { 3693 unsigned int tmp = *dp & (0xf0f >> (4 - dshift)); 3694 tmp |= v << dshift; 3695 *dp = (png_byte)(tmp & 0xff); 3696 3697 if (dshift == s_end) 3698 { 3699 dshift = s_start; 3700 dp--; 3701 } 3702 3703 else 3704 dshift += s_inc; 3705 } 3706 3707 if (sshift == s_end) 3708 { 3709 sshift = s_start; 3710 sp--; 3711 } 3712 3713 else 3714 sshift += s_inc; 3715 } 3716 break; 3717 } 3718 3719 default: 3720 { 3721 png_size_t pixel_bytes = (row_info->pixel_depth >> 3); 3722 3723 png_bytep sp = row + (png_size_t)(row_info->width - 1) 3724 * pixel_bytes; 3725 3726 png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes; 3727 3728 int jstop = png_pass_inc[pass]; 3729 png_uint_32 i; 3730 3731 for (i = 0; i < row_info->width; i++) 3732 { 3733 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */ 3734 int j; 3735 3736 memcpy(v, sp, pixel_bytes); 3737 3738 for (j = 0; j < jstop; j++) 3739 { 3740 memcpy(dp, v, pixel_bytes); 3741 dp -= pixel_bytes; 3742 } 3743 3744 sp -= pixel_bytes; 3745 } 3746 break; 3747 } 3748 } 3749 3750 row_info->width = final_width; 3751 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width); 3752 } 3753 #ifndef PNG_READ_PACKSWAP_SUPPORTED 3754 PNG_UNUSED(transformations) /* Silence compiler warning */ 3755 #endif 3756 } 3757 #endif /* PNG_READ_INTERLACING_SUPPORTED */ 3758 3759 static void 3760 png_read_filter_row_sub(png_row_infop row_info, png_bytep row, 3761 png_const_bytep prev_row) 3762 { 3763 png_size_t i; 3764 png_size_t istop = row_info->rowbytes; 3765 unsigned int bpp = (row_info->pixel_depth + 7) >> 3; 3766 png_bytep rp = row + bpp; 3767 3768 PNG_UNUSED(prev_row) 3769 3770 for (i = bpp; i < istop; i++) 3771 { 3772 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff); 3773 rp++; 3774 } 3775 } 3776 3777 static void 3778 png_read_filter_row_up(png_row_infop row_info, png_bytep row, 3779 png_const_bytep prev_row) 3780 { 3781 png_size_t i; 3782 png_size_t istop = row_info->rowbytes; 3783 png_bytep rp = row; 3784 png_const_bytep pp = prev_row; 3785 3786 for (i = 0; i < istop; i++) 3787 { 3788 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff); 3789 rp++; 3790 } 3791 } 3792 3793 static void 3794 png_read_filter_row_avg(png_row_infop row_info, png_bytep row, 3795 png_const_bytep prev_row) 3796 { 3797 png_size_t i; 3798 png_bytep rp = row; 3799 png_const_bytep pp = prev_row; 3800 unsigned int bpp = (row_info->pixel_depth + 7) >> 3; 3801 png_size_t istop = row_info->rowbytes - bpp; 3802 3803 for (i = 0; i < bpp; i++) 3804 { 3805 *rp = (png_byte)(((int)(*rp) + 3806 ((int)(*pp++) / 2 )) & 0xff); 3807 3808 rp++; 3809 } 3810 3811 for (i = 0; i < istop; i++) 3812 { 3813 *rp = (png_byte)(((int)(*rp) + 3814 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff); 3815 3816 rp++; 3817 } 3818 } 3819 3820 static void 3821 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row, 3822 png_const_bytep prev_row) 3823 { 3824 png_bytep rp_end = row + row_info->rowbytes; 3825 int a, c; 3826 3827 /* First pixel/byte */ 3828 c = *prev_row++; 3829 a = *row + c; 3830 *row++ = (png_byte)a; 3831 3832 /* Remainder */ 3833 while (row < rp_end) 3834 { 3835 int b, pa, pb, pc, p; 3836 3837 a &= 0xff; /* From previous iteration or start */ 3838 b = *prev_row++; 3839 3840 p = b - c; 3841 pc = a - c; 3842 3843 # ifdef PNG_USE_ABS 3844 pa = abs(p); 3845 pb = abs(pc); 3846 pc = abs(p + pc); 3847 # else 3848 pa = p < 0 ? -p : p; 3849 pb = pc < 0 ? -pc : pc; 3850 pc = (p + pc) < 0 ? -(p + pc) : p + pc; 3851 # endif 3852 3853 /* Find the best predictor, the least of pa, pb, pc favoring the earlier 3854 * ones in the case of a tie. 3855 */ 3856 if (pb < pa) pa = pb, a = b; 3857 if (pc < pa) a = c; 3858 3859 /* Calculate the current pixel in a, and move the previous row pixel to c 3860 * for the next time round the loop 3861 */ 3862 c = b; 3863 a += *row; 3864 *row++ = (png_byte)a; 3865 } 3866 } 3867 3868 static void 3869 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row, 3870 png_const_bytep prev_row) 3871 { 3872 int bpp = (row_info->pixel_depth + 7) >> 3; 3873 png_bytep rp_end = row + bpp; 3874 3875 /* Process the first pixel in the row completely (this is the same as 'up' 3876 * because there is only one candidate predictor for the first row). 3877 */ 3878 while (row < rp_end) 3879 { 3880 int a = *row + *prev_row++; 3881 *row++ = (png_byte)a; 3882 } 3883 3884 /* Remainder */ 3885 rp_end += row_info->rowbytes - bpp; 3886 3887 while (row < rp_end) 3888 { 3889 int a, b, c, pa, pb, pc, p; 3890 3891 c = *(prev_row - bpp); 3892 a = *(row - bpp); 3893 b = *prev_row++; 3894 3895 p = b - c; 3896 pc = a - c; 3897 3898 # ifdef PNG_USE_ABS 3899 pa = abs(p); 3900 pb = abs(pc); 3901 pc = abs(p + pc); 3902 # else 3903 pa = p < 0 ? -p : p; 3904 pb = pc < 0 ? -pc : pc; 3905 pc = (p + pc) < 0 ? -(p + pc) : p + pc; 3906 # endif 3907 3908 if (pb < pa) pa = pb, a = b; 3909 if (pc < pa) a = c; 3910 3911 a += *row; 3912 *row++ = (png_byte)a; 3913 } 3914 } 3915 3916 static void 3917 png_init_filter_functions(png_structrp pp) 3918 /* This function is called once for every PNG image (except for PNG images 3919 * that only use PNG_FILTER_VALUE_NONE for all rows) to set the 3920 * implementations required to reverse the filtering of PNG rows. Reversing 3921 * the filter is the first transformation performed on the row data. It is 3922 * performed in place, therefore an implementation can be selected based on 3923 * the image pixel format. If the implementation depends on image width then 3924 * take care to ensure that it works correctly if the image is interlaced - 3925 * interlacing causes the actual row width to vary. 3926 */ 3927 { 3928 unsigned int bpp = (pp->pixel_depth + 7) >> 3; 3929 3930 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub; 3931 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up; 3932 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg; 3933 if (bpp == 1) 3934 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = 3935 png_read_filter_row_paeth_1byte_pixel; 3936 else 3937 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = 3938 png_read_filter_row_paeth_multibyte_pixel; 3939 3940 #ifdef PNG_FILTER_OPTIMIZATIONS 3941 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to 3942 * call to install hardware optimizations for the above functions; simply 3943 * replace whatever elements of the pp->read_filter[] array with a hardware 3944 * specific (or, for that matter, generic) optimization. 3945 * 3946 * To see an example of this examine what configure.ac does when 3947 * --enable-arm-neon is specified on the command line. 3948 */ 3949 PNG_FILTER_OPTIMIZATIONS(pp, bpp); 3950 #endif 3951 } 3952 3953 void /* PRIVATE */ 3954 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row, 3955 png_const_bytep prev_row, int filter) 3956 { 3957 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define 3958 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic 3959 * implementations. See png_init_filter_functions above. 3960 */ 3961 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST) 3962 { 3963 if (pp->read_filter[0] == NULL) 3964 png_init_filter_functions(pp); 3965 3966 pp->read_filter[filter-1](row_info, row, prev_row); 3967 } 3968 } 3969 3970 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 3971 void /* PRIVATE */ 3972 png_read_IDAT_data(png_structrp png_ptr, png_bytep output, 3973 png_alloc_size_t avail_out) 3974 { 3975 /* Loop reading IDATs and decompressing the result into output[avail_out] */ 3976 png_ptr->zstream.next_out = output; 3977 png_ptr->zstream.avail_out = 0; /* safety: set below */ 3978 3979 if (output == NULL) 3980 avail_out = 0; 3981 3982 do 3983 { 3984 int ret; 3985 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE]; 3986 3987 if (png_ptr->zstream.avail_in == 0) 3988 { 3989 uInt avail_in; 3990 png_bytep buffer; 3991 3992 while (png_ptr->idat_size == 0) 3993 { 3994 #ifdef PNG_INDEX_SUPPORTED 3995 if (png_ptr->index) { 3996 png_opt_crc_finish(png_ptr, 0); 3997 png_ptr->index->stream_idat_position = png_ptr->total_data_read; 3998 } else 3999 #endif 4000 png_crc_finish(png_ptr, 0); 4001 4002 png_ptr->idat_size = png_read_chunk_header(png_ptr); 4003 /* This is an error even in the 'check' case because the code just 4004 * consumed a non-IDAT header. 4005 */ 4006 if (png_ptr->chunk_name != png_IDAT) 4007 png_error(png_ptr, "Not enough image data"); 4008 } 4009 4010 avail_in = png_ptr->IDAT_read_size; 4011 4012 if (avail_in > png_ptr->idat_size) 4013 avail_in = (uInt)png_ptr->idat_size; 4014 4015 /* A PNG with a gradually increasing IDAT size will defeat this attempt 4016 * to minimize memory usage by causing lots of re-allocs, but 4017 * realistically doing IDAT_read_size re-allocs is not likely to be a 4018 * big problem. 4019 */ 4020 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/); 4021 4022 png_crc_read(png_ptr, buffer, avail_in); 4023 png_ptr->idat_size -= avail_in; 4024 4025 png_ptr->zstream.next_in = buffer; 4026 png_ptr->zstream.avail_in = avail_in; 4027 } 4028 4029 /* And set up the output side. */ 4030 if (output != NULL) /* standard read */ 4031 { 4032 uInt out = ZLIB_IO_MAX; 4033 4034 if (out > avail_out) 4035 out = (uInt)avail_out; 4036 4037 avail_out -= out; 4038 png_ptr->zstream.avail_out = out; 4039 } 4040 4041 else /* after last row, checking for end */ 4042 { 4043 png_ptr->zstream.next_out = tmpbuf; 4044 png_ptr->zstream.avail_out = (sizeof tmpbuf); 4045 } 4046 4047 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the 4048 * process. If the LZ stream is truncated the sequential reader will 4049 * terminally damage the stream, above, by reading the chunk header of the 4050 * following chunk (it then exits with png_error). 4051 * 4052 * TODO: deal more elegantly with truncated IDAT lists. 4053 */ 4054 ret = inflate(&png_ptr->zstream, Z_NO_FLUSH); 4055 4056 /* Take the unconsumed output back. */ 4057 if (output != NULL) 4058 avail_out += png_ptr->zstream.avail_out; 4059 4060 else /* avail_out counts the extra bytes */ 4061 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out; 4062 4063 png_ptr->zstream.avail_out = 0; 4064 4065 if (ret == Z_STREAM_END) 4066 { 4067 /* Do this for safety; we won't read any more into this row. */ 4068 png_ptr->zstream.next_out = NULL; 4069 4070 png_ptr->mode |= PNG_AFTER_IDAT; 4071 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; 4072 4073 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0) 4074 png_chunk_benign_error(png_ptr, "Extra compressed data"); 4075 break; 4076 } 4077 4078 if (ret != Z_OK) 4079 #ifdef PNG_INDEX_SUPPORTED 4080 if (png_ptr->index && png_ptr->row_number != png_ptr->height - 1) 4081 #endif 4082 { 4083 png_zstream_error(png_ptr, ret); 4084 4085 if (output != NULL) 4086 png_chunk_error(png_ptr, png_ptr->zstream.msg); 4087 4088 else /* checking */ 4089 { 4090 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg); 4091 return; 4092 } 4093 } 4094 } while (avail_out > 0); 4095 4096 if (avail_out > 0) 4097 { 4098 /* The stream ended before the image; this is the same as too few IDATs so 4099 * should be handled the same way. 4100 */ 4101 if (output != NULL) 4102 png_error(png_ptr, "Not enough image data"); 4103 4104 else /* the deflate stream contained extra data */ 4105 png_chunk_benign_error(png_ptr, "Too much image data"); 4106 } 4107 } 4108 4109 void /* PRIVATE */ 4110 png_read_finish_IDAT(png_structrp png_ptr) 4111 { 4112 /* We don't need any more data and the stream should have ended, however the 4113 * LZ end code may actually not have been processed. In this case we must 4114 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk 4115 * may still remain to be consumed. 4116 */ 4117 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) 4118 { 4119 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in 4120 * the compressed stream, but the stream may be damaged too, so even after 4121 * this call we may need to terminate the zstream ownership. 4122 */ 4123 png_read_IDAT_data(png_ptr, NULL, 0); 4124 png_ptr->zstream.next_out = NULL; /* safety */ 4125 4126 /* Now clear everything out for safety; the following may not have been 4127 * done. 4128 */ 4129 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) 4130 { 4131 png_ptr->mode |= PNG_AFTER_IDAT; 4132 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; 4133 } 4134 } 4135 4136 /* If the zstream has not been released do it now *and* terminate the reading 4137 * of the final IDAT chunk. 4138 */ 4139 if (png_ptr->zowner == png_IDAT) 4140 { 4141 /* Always do this; the pointers otherwise point into the read buffer. */ 4142 png_ptr->zstream.next_in = NULL; 4143 png_ptr->zstream.avail_in = 0; 4144 4145 /* Now we no longer own the zstream. */ 4146 png_ptr->zowner = 0; 4147 4148 /* The slightly weird semantics of the sequential IDAT reading is that we 4149 * are always in or at the end of an IDAT chunk, so we always need to do a 4150 * crc_finish here. If idat_size is non-zero we also need to read the 4151 * spurious bytes at the end of the chunk now. 4152 */ 4153 #ifdef PNG_INDEX_SUPPORTED 4154 if (png_ptr->index) 4155 { 4156 (void)png_opt_crc_finish(png_ptr, png_ptr->idat_size); 4157 png_ptr->index->stream_idat_position = png_ptr->total_data_read; 4158 } 4159 else 4160 #endif 4161 (void)png_crc_finish(png_ptr, png_ptr->idat_size); 4162 } 4163 } 4164 4165 #ifdef PNG_INDEX_SUPPORTED 4166 void /* PRIVATE */ 4167 png_set_interlaced_pass(png_structp png_ptr, int pass) 4168 { 4169 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 4170 /* Start of interlace block */ 4171 PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 4172 /* Offset to next interlace block */ 4173 PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 4174 /* Start of interlace block in the y direction */ 4175 PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; 4176 /* Offset to next interlace block in the y direction */ 4177 PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; 4178 png_ptr->pass = pass; 4179 png_ptr->iwidth = (png_ptr->width + 4180 png_pass_inc[png_ptr->pass] - 1 - 4181 png_pass_start[png_ptr->pass]) / 4182 png_pass_inc[png_ptr->pass]; 4183 } 4184 #endif 4185 4186 void /* PRIVATE */ 4187 png_read_finish_row(png_structrp png_ptr) 4188 { 4189 #ifdef PNG_READ_INTERLACING_SUPPORTED 4190 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 4191 4192 /* Start of interlace block */ 4193 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 4194 4195 /* Offset to next interlace block */ 4196 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 4197 4198 /* Start of interlace block in the y direction */ 4199 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; 4200 4201 /* Offset to next interlace block in the y direction */ 4202 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; 4203 #endif /* PNG_READ_INTERLACING_SUPPORTED */ 4204 4205 png_debug(1, "in png_read_finish_row"); 4206 png_ptr->row_number++; 4207 if (png_ptr->row_number < png_ptr->num_rows) 4208 return; 4209 4210 #ifdef PNG_READ_INTERLACING_SUPPORTED 4211 if (png_ptr->interlaced) 4212 { 4213 png_ptr->row_number = 0; 4214 4215 /* TO DO: don't do this if prev_row isn't needed (requires 4216 * read-ahead of the next row's filter byte. 4217 */ 4218 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); 4219 4220 do 4221 { 4222 png_ptr->pass++; 4223 4224 if (png_ptr->pass >= 7) 4225 break; 4226 4227 png_ptr->iwidth = (png_ptr->width + 4228 png_pass_inc[png_ptr->pass] - 1 - 4229 png_pass_start[png_ptr->pass]) / 4230 png_pass_inc[png_ptr->pass]; 4231 4232 if (!(png_ptr->transformations & PNG_INTERLACE)) 4233 { 4234 png_ptr->num_rows = (png_ptr->height + 4235 png_pass_yinc[png_ptr->pass] - 1 - 4236 png_pass_ystart[png_ptr->pass]) / 4237 png_pass_yinc[png_ptr->pass]; 4238 } 4239 4240 else /* if (png_ptr->transformations & PNG_INTERLACE) */ 4241 break; /* libpng deinterlacing sees every row */ 4242 4243 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0); 4244 4245 if (png_ptr->pass < 7) 4246 return; 4247 } 4248 #endif /* PNG_READ_INTERLACING_SUPPORTED */ 4249 4250 /* Here after at the end of the last row of the last pass. */ 4251 png_read_finish_IDAT(png_ptr); 4252 } 4253 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ 4254 4255 void /* PRIVATE */ 4256 png_read_start_row(png_structrp png_ptr) 4257 { 4258 #ifdef PNG_READ_INTERLACING_SUPPORTED 4259 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 4260 4261 /* Start of interlace block */ 4262 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 4263 4264 /* Offset to next interlace block */ 4265 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 4266 4267 /* Start of interlace block in the y direction */ 4268 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; 4269 4270 /* Offset to next interlace block in the y direction */ 4271 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; 4272 #endif 4273 4274 int max_pixel_depth; 4275 png_size_t row_bytes; 4276 4277 png_debug(1, "in png_read_start_row"); 4278 4279 #ifdef PNG_READ_TRANSFORMS_SUPPORTED 4280 png_init_read_transformations(png_ptr); 4281 #endif 4282 #ifdef PNG_READ_INTERLACING_SUPPORTED 4283 if (png_ptr->interlaced) 4284 { 4285 if (!(png_ptr->transformations & PNG_INTERLACE)) 4286 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 - 4287 png_pass_ystart[0]) / png_pass_yinc[0]; 4288 4289 else 4290 png_ptr->num_rows = png_ptr->height; 4291 4292 png_ptr->iwidth = (png_ptr->width + 4293 png_pass_inc[png_ptr->pass] - 1 - 4294 png_pass_start[png_ptr->pass]) / 4295 png_pass_inc[png_ptr->pass]; 4296 } 4297 4298 else 4299 #endif /* PNG_READ_INTERLACING_SUPPORTED */ 4300 { 4301 png_ptr->num_rows = png_ptr->height; 4302 png_ptr->iwidth = png_ptr->width; 4303 } 4304 4305 max_pixel_depth = png_ptr->pixel_depth; 4306 4307 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of 4308 * calculations to calculate the final pixel depth, then 4309 * png_do_read_transforms actually does the transforms. This means that the 4310 * code which effectively calculates this value is actually repeated in three 4311 * separate places. They must all match. Innocent changes to the order of 4312 * transformations can and will break libpng in a way that causes memory 4313 * overwrites. 4314 * 4315 * TODO: fix this. 4316 */ 4317 #ifdef PNG_READ_PACK_SUPPORTED 4318 if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8) 4319 max_pixel_depth = 8; 4320 #endif 4321 4322 #ifdef PNG_READ_EXPAND_SUPPORTED 4323 if (png_ptr->transformations & PNG_EXPAND) 4324 { 4325 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 4326 { 4327 if (png_ptr->num_trans) 4328 max_pixel_depth = 32; 4329 4330 else 4331 max_pixel_depth = 24; 4332 } 4333 4334 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) 4335 { 4336 if (max_pixel_depth < 8) 4337 max_pixel_depth = 8; 4338 4339 if (png_ptr->num_trans) 4340 max_pixel_depth *= 2; 4341 } 4342 4343 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB) 4344 { 4345 if (png_ptr->num_trans) 4346 { 4347 max_pixel_depth *= 4; 4348 max_pixel_depth /= 3; 4349 } 4350 } 4351 } 4352 #endif 4353 4354 #ifdef PNG_READ_EXPAND_16_SUPPORTED 4355 if (png_ptr->transformations & PNG_EXPAND_16) 4356 { 4357 # ifdef PNG_READ_EXPAND_SUPPORTED 4358 /* In fact it is an error if it isn't supported, but checking is 4359 * the safe way. 4360 */ 4361 if (png_ptr->transformations & PNG_EXPAND) 4362 { 4363 if (png_ptr->bit_depth < 16) 4364 max_pixel_depth *= 2; 4365 } 4366 else 4367 # endif 4368 png_ptr->transformations &= ~PNG_EXPAND_16; 4369 } 4370 #endif 4371 4372 #ifdef PNG_READ_FILLER_SUPPORTED 4373 if (png_ptr->transformations & (PNG_FILLER)) 4374 { 4375 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) 4376 { 4377 if (max_pixel_depth <= 8) 4378 max_pixel_depth = 16; 4379 4380 else 4381 max_pixel_depth = 32; 4382 } 4383 4384 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB || 4385 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 4386 { 4387 if (max_pixel_depth <= 32) 4388 max_pixel_depth = 32; 4389 4390 else 4391 max_pixel_depth = 64; 4392 } 4393 } 4394 #endif 4395 4396 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 4397 if (png_ptr->transformations & PNG_GRAY_TO_RGB) 4398 { 4399 if ( 4400 #ifdef PNG_READ_EXPAND_SUPPORTED 4401 (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) || 4402 #endif 4403 #ifdef PNG_READ_FILLER_SUPPORTED 4404 (png_ptr->transformations & (PNG_FILLER)) || 4405 #endif 4406 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) 4407 { 4408 if (max_pixel_depth <= 16) 4409 max_pixel_depth = 32; 4410 4411 else 4412 max_pixel_depth = 64; 4413 } 4414 4415 else 4416 { 4417 if (max_pixel_depth <= 8) 4418 { 4419 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 4420 max_pixel_depth = 32; 4421 4422 else 4423 max_pixel_depth = 24; 4424 } 4425 4426 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 4427 max_pixel_depth = 64; 4428 4429 else 4430 max_pixel_depth = 48; 4431 } 4432 } 4433 #endif 4434 4435 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \ 4436 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) 4437 if (png_ptr->transformations & PNG_USER_TRANSFORM) 4438 { 4439 int user_pixel_depth = png_ptr->user_transform_depth * 4440 png_ptr->user_transform_channels; 4441 4442 if (user_pixel_depth > max_pixel_depth) 4443 max_pixel_depth = user_pixel_depth; 4444 } 4445 #endif 4446 4447 /* This value is stored in png_struct and double checked in the row read 4448 * code. 4449 */ 4450 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth; 4451 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */ 4452 4453 /* Align the width on the next larger 8 pixels. Mainly used 4454 * for interlacing 4455 */ 4456 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7)); 4457 /* Calculate the maximum bytes needed, adding a byte and a pixel 4458 * for safety's sake 4459 */ 4460 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) + 4461 1 + ((max_pixel_depth + 7) >> 3); 4462 4463 #ifdef PNG_MAX_MALLOC_64K 4464 if (row_bytes > (png_uint_32)65536L) 4465 png_error(png_ptr, "This image requires a row greater than 64KB"); 4466 #endif 4467 4468 if (row_bytes + 48 > png_ptr->old_big_row_buf_size) 4469 { 4470 png_free(png_ptr, png_ptr->big_row_buf); 4471 png_free(png_ptr, png_ptr->big_prev_row); 4472 4473 if (png_ptr->interlaced) 4474 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr, 4475 row_bytes + 48); 4476 4477 else 4478 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48); 4479 4480 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48); 4481 4482 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED 4483 /* Use 16-byte aligned memory for row_buf with at least 16 bytes 4484 * of padding before and after row_buf; treat prev_row similarly. 4485 * NOTE: the alignment is to the start of the pixels, one beyond the start 4486 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this 4487 * was incorrect; the filter byte was aligned, which had the exact 4488 * opposite effect of that intended. 4489 */ 4490 { 4491 png_bytep temp = png_ptr->big_row_buf + 32; 4492 int extra = (int)((temp - (png_bytep)0) & 0x0f); 4493 png_ptr->row_buf = temp - extra - 1/*filter byte*/; 4494 4495 temp = png_ptr->big_prev_row + 32; 4496 extra = (int)((temp - (png_bytep)0) & 0x0f); 4497 png_ptr->prev_row = temp - extra - 1/*filter byte*/; 4498 } 4499 4500 #else 4501 /* Use 31 bytes of padding before and 17 bytes after row_buf. */ 4502 png_ptr->row_buf = png_ptr->big_row_buf + 31; 4503 png_ptr->prev_row = png_ptr->big_prev_row + 31; 4504 #endif 4505 png_ptr->old_big_row_buf_size = row_bytes + 48; 4506 } 4507 4508 #ifdef PNG_MAX_MALLOC_64K 4509 if (png_ptr->rowbytes > 65535) 4510 png_error(png_ptr, "This image requires a row greater than 64KB"); 4511 4512 #endif 4513 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1)) 4514 png_error(png_ptr, "Row has too many bytes to allocate in memory"); 4515 4516 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); 4517 4518 png_debug1(3, "width = %u,", png_ptr->width); 4519 png_debug1(3, "height = %u,", png_ptr->height); 4520 png_debug1(3, "iwidth = %u,", png_ptr->iwidth); 4521 png_debug1(3, "num_rows = %u,", png_ptr->num_rows); 4522 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes); 4523 png_debug1(3, "irowbytes = %lu", 4524 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1); 4525 4526 /* The sequential reader needs a buffer for IDAT, but the progressive reader 4527 * does not, so free the read buffer now regardless; the sequential reader 4528 * reallocates it on demand. 4529 */ 4530 if (png_ptr->read_buffer) 4531 { 4532 png_bytep buffer = png_ptr->read_buffer; 4533 4534 png_ptr->read_buffer_size = 0; 4535 png_ptr->read_buffer = NULL; 4536 png_free(png_ptr, buffer); 4537 } 4538 4539 /* Finally claim the zstream for the inflate of the IDAT data, use the bits 4540 * value from the stream (note that this will result in a fatal error if the 4541 * IDAT stream has a bogus deflate header window_bits value, but this should 4542 * not be happening any longer!) 4543 */ 4544 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK) 4545 png_error(png_ptr, png_ptr->zstream.msg); 4546 4547 png_ptr->flags |= PNG_FLAG_ROW_INIT; 4548 } 4549 #endif /* PNG_READ_SUPPORTED */ 4550