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