forked from pnggroup/libpng
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathpngrutil.c
4478 lines (3724 loc) · 138 KB
/
pngrutil.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* pngrutil.c - utilities to read a PNG file
*
* Last changed in libpng 1.6.18 [July 23, 2015]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* This file contains routines that are only called from within
* libpng itself during the course of reading an image.
*/
#include "pngpriv.h"
#ifdef PNG_READ_SUPPORTED
png_uint_32 PNGAPI
png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval > PNG_UINT_31_MAX)
png_error(png_ptr, "PNG unsigned integer out of range");
return (uval);
}
#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
/* The following is a variation on the above for use with the fixed
* point values used for gAMA and cHRM. Instead of png_error it
* issues a warning and returns (-1) - an invalid value because both
* gAMA and cHRM use *unsigned* integers for fixed point values.
*/
#define PNG_FIXED_ERROR (-1)
static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval <= PNG_UINT_31_MAX)
return (png_fixed_point)uval; /* known to be in range */
/* The caller can turn off the warning by passing NULL. */
if (png_ptr != NULL)
png_warning(png_ptr, "PNG fixed point integer out of range");
return PNG_FIXED_ERROR;
}
#endif
#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
/* NOTE: the read macros will obscure these definitions, so that if
* PNG_USE_READ_MACROS is set the library will not use them internally,
* but the APIs will still be available externally.
*
* The parentheses around "PNGAPI function_name" in the following three
* functions are necessary because they allow the macros to co-exist with
* these (unused but exported) functions.
*/
/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32 (PNGAPI
png_get_uint_32)(png_const_bytep buf)
{
png_uint_32 uval =
((png_uint_32)(*(buf )) << 24) +
((png_uint_32)(*(buf + 1)) << 16) +
((png_uint_32)(*(buf + 2)) << 8) +
((png_uint_32)(*(buf + 3)) ) ;
return uval;
}
/* Grab a signed 32-bit integer from a buffer in big-endian format. The
* data is stored in the PNG file in two's complement format and there
* is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
* the following code does a two's complement to native conversion.
*/
png_int_32 (PNGAPI
png_get_int_32)(png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if ((uval & 0x80000000) == 0) /* non-negative */
return uval;
uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
return -(png_int_32)uval;
}
/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16 (PNGAPI
png_get_uint_16)(png_const_bytep buf)
{
/* ANSI-C requires an int value to accomodate at least 16 bits so this
* works and allows the compiler not to worry about possible narrowing
* on 32 bit systems. (Pre-ANSI systems did not make integers smaller
* than 16 bits either.)
*/
unsigned int val =
((unsigned int)(*buf) << 8) +
((unsigned int)(*(buf + 1)));
return (png_uint_16)val;
}
#endif /* READ_INT_FUNCTIONS */
/* Read and check the PNG file signature */
void /* PRIVATE */
png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
{
png_size_t num_checked, num_to_check;
/* Exit if the user application does not expect a signature. */
if (png_ptr->sig_bytes >= 8)
return;
num_checked = png_ptr->sig_bytes;
num_to_check = 8 - num_checked;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
#endif
/* The signature must be serialized in a single I/O call. */
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
{
if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
png_error(png_ptr, "Not a PNG file");
else
png_error(png_ptr, "PNG file corrupted by ASCII conversion");
}
if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Read the chunk header (length + type name).
* Put the type name into png_ptr->chunk_name, and return the length.
*/
png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structrp png_ptr)
{
png_byte buf[8];
png_uint_32 length;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
#endif
/* Read the length and the chunk name.
* This must be performed in a single I/O call.
*/
png_read_data(png_ptr, buf, 8);
length = png_get_uint_31(png_ptr, buf);
/* Put the chunk name into png_ptr->chunk_name. */
png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
png_debug2(0, "Reading %lx chunk, length = %lu",
(unsigned long)png_ptr->chunk_name, (unsigned long)length);
/* Reset the crc and run it over the chunk name. */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
/* Check to see if chunk name is valid. */
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
#endif
return length;
}
/* Read data, and (optionally) run it through the CRC. */
void /* PRIVATE */
png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
{
if (png_ptr == NULL)
return;
png_read_data(png_ptr, buf, length);
png_calculate_crc(png_ptr, buf, length);
}
/* Optionally skip data and then check the CRC. Depending on whether we
* are reading an ancillary or critical chunk, and how the program has set
* things up, we may calculate the CRC on the data and print a message.
* Returns '1' if there was a CRC error, '0' otherwise.
*/
int /* PRIVATE */
png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
{
/* The size of the local buffer for inflate is a good guess as to a
* reasonable size to use for buffering reads from the application.
*/
while (skip > 0)
{
png_uint_32 len;
png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
len = (sizeof tmpbuf);
if (len > skip)
len = skip;
skip -= len;
png_crc_read(png_ptr, tmpbuf, len);
}
if (png_crc_error(png_ptr) != 0)
{
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
(png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
{
png_chunk_warning(png_ptr, "CRC error");
}
else
png_chunk_error(png_ptr, "CRC error");
return (1);
}
return (0);
}
/* Compare the CRC stored in the PNG file with that calculated by libpng from
* the data it has read thus far.
*/
int /* PRIVATE */
png_crc_error(png_structrp png_ptr)
{
png_byte crc_bytes[4];
png_uint_32 crc;
int need_crc = 1;
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
{
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
need_crc = 0;
}
else /* critical */
{
if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
need_crc = 0;
}
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
#endif
/* The chunk CRC must be serialized in a single I/O call. */
png_read_data(png_ptr, crc_bytes, 4);
if (need_crc != 0)
{
crc = png_get_uint_32(crc_bytes);
return ((int)(crc != png_ptr->crc));
}
else
return (0);
}
#if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
/* Manage the read buffer; this simply reallocates the buffer if it is not small
* enough (or if it is not allocated). The routine returns a pointer to the
* buffer; if an error occurs and 'warn' is set the routine returns NULL, else
* it will call png_error (via png_malloc) on failure. (warn == 2 means
* 'silent').
*/
static png_bytep
png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
{
png_bytep buffer = png_ptr->read_buffer;
if (buffer != NULL && new_size > png_ptr->read_buffer_size)
{
png_ptr->read_buffer = NULL;
png_ptr->read_buffer = NULL;
png_ptr->read_buffer_size = 0;
png_free(png_ptr, buffer);
buffer = NULL;
}
if (buffer == NULL)
{
buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
if (buffer != NULL)
{
png_ptr->read_buffer = buffer;
png_ptr->read_buffer_size = new_size;
}
else if (warn < 2) /* else silent */
{
if (warn != 0)
png_chunk_warning(png_ptr, "insufficient memory to read chunk");
else
png_chunk_error(png_ptr, "insufficient memory to read chunk");
}
}
return buffer;
}
#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
* decompression. Returns Z_OK on success, else a zlib error code. It checks
* the owner but, in final release builds, just issues a warning if some other
* chunk apparently owns the stream. Prior to release it does a png_error.
*/
static int
png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
{
if (png_ptr->zowner != 0)
{
char msg[64];
PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
/* So the message that results is "<chunk> using zstream"; this is an
* internal error, but is very useful for debugging. i18n requirements
* are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 4, " using zstream");
#if PNG_RELEASE_BUILD
png_chunk_warning(png_ptr, msg);
png_ptr->zowner = 0;
#else
png_chunk_error(png_ptr, msg);
#endif
}
/* Implementation note: unlike 'png_deflate_claim' this internal function
* does not take the size of the data as an argument. Some efficiency could
* be gained by using this when it is known *if* the zlib stream itself does
* not record the number; however, this is an illusion: the original writer
* of the PNG may have selected a lower window size, and we really must
* follow that because, for systems with with limited capabilities, we
* would otherwise reject the application's attempts to use a smaller window
* size (zlib doesn't have an interface to say "this or lower"!).
*
* inflateReset2 was added to zlib 1.2.4; before this the window could not be
* reset, therefore it is necessary to always allocate the maximum window
* size with earlier zlibs just in case later compressed chunks need it.
*/
{
int ret; /* zlib return code */
#if PNG_ZLIB_VERNUM >= 0x1240
# if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
int window_bits;
if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
PNG_OPTION_ON)
window_bits = 15;
else
window_bits = 0;
# else
# define window_bits 0
# endif
#endif
/* Set this for safety, just in case the previous owner left pointers to
* memory allocations.
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
{
#if PNG_ZLIB_VERNUM < 0x1240
ret = inflateReset(&png_ptr->zstream);
#else
ret = inflateReset2(&png_ptr->zstream, window_bits);
#endif
}
else
{
#if PNG_ZLIB_VERNUM < 0x1240
ret = inflateInit(&png_ptr->zstream);
#else
ret = inflateInit2(&png_ptr->zstream, window_bits);
#endif
if (ret == Z_OK)
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
}
if (ret == Z_OK)
png_ptr->zowner = owner;
else
png_zstream_error(png_ptr, ret);
return ret;
}
#ifdef window_bits
# undef window_bits
#endif
}
#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
* allow the caller to do multiple calls if required. If the 'finish' flag is
* set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
* be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
* Z_OK or Z_STREAM_END will be returned on success.
*
* The input and output sizes are updated to the actual amounts of data consumed
* or written, not the amount available (as in a z_stream). The data pointers
* are not changed, so the next input is (data+input_size) and the next
* available output is (output+output_size).
*/
static int
png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
/* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
/* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
{
if (png_ptr->zowner == owner) /* Else not claimed */
{
int ret;
png_alloc_size_t avail_out = *output_size_ptr;
png_uint_32 avail_in = *input_size_ptr;
/* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
* can't even necessarily handle 65536 bytes) because the type uInt is
* "16 bits or more". Consequently it is necessary to chunk the input to
* zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
* maximum value that can be stored in a uInt.) It is possible to set
* ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
* a performance advantage, because it reduces the amount of data accessed
* at each step and that may give the OS more time to page it in.
*/
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
/* avail_in and avail_out are set below from 'size' */
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.avail_out = 0;
/* Read directly into the output if it is available (this is set to
* a local buffer below if output is NULL).
*/
if (output != NULL)
png_ptr->zstream.next_out = output;
do
{
uInt avail;
Byte local_buffer[PNG_INFLATE_BUF_SIZE];
/* zlib INPUT BUFFER */
/* The setting of 'avail_in' used to be outside the loop; by setting it
* inside it is possible to chunk the input to zlib and simply rely on
* zlib to advance the 'next_in' pointer. This allows arbitrary
* amounts of data to be passed through zlib at the unavoidable cost of
* requiring a window save (memcpy of up to 32768 output bytes)
* every ZLIB_IO_MAX input bytes.
*/
avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
avail = ZLIB_IO_MAX;
if (avail_in < avail)
avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
avail_in -= avail;
png_ptr->zstream.avail_in = avail;
/* zlib OUTPUT BUFFER */
avail_out += png_ptr->zstream.avail_out; /* not written last time */
avail = ZLIB_IO_MAX; /* maximum zlib can process */
if (output == NULL)
{
/* Reset the output buffer each time round if output is NULL and
* make available the full buffer, up to 'remaining_space'
*/
png_ptr->zstream.next_out = local_buffer;
if ((sizeof local_buffer) < avail)
avail = (sizeof local_buffer);
}
if (avail_out < avail)
avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
png_ptr->zstream.avail_out = avail;
avail_out -= avail;
/* zlib inflate call */
/* In fact 'avail_out' may be 0 at this point, that happens at the end
* of the read when the final LZ end code was not passed at the end of
* the previous chunk of input data. Tell zlib if we have reached the
* end of the output buffer.
*/
ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
(finish ? Z_FINISH : Z_SYNC_FLUSH));
} while (ret == Z_OK);
/* For safety kill the local buffer pointer now */
if (output == NULL)
png_ptr->zstream.next_out = NULL;
/* Claw back the 'size' and 'remaining_space' byte counts. */
avail_in += png_ptr->zstream.avail_in;
avail_out += png_ptr->zstream.avail_out;
/* Update the input and output sizes; the updated values are the amount
* consumed or written, effectively the inverse of what zlib uses.
*/
if (avail_out > 0)
*output_size_ptr -= avail_out;
if (avail_in > 0)
*input_size_ptr -= avail_in;
/* Ensure png_ptr->zstream.msg is set (even in the success case!) */
png_zstream_error(png_ptr, ret);
return ret;
}
else
{
/* This is a bad internal error. The recovery assigns to the zstream msg
* pointer, which is not owned by the caller, but this is safe; it's only
* used on errors!
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
return Z_STREAM_ERROR;
}
}
/*
* Decompress trailing data in a chunk. The assumption is that read_buffer
* points at an allocated area holding the contents of a chunk with a
* trailing compressed part. What we get back is an allocated area
* holding the original prefix part and an uncompressed version of the
* trailing part (the malloc area passed in is freed).
*/
static int
png_decompress_chunk(png_structrp png_ptr,
png_uint_32 chunklength, png_uint_32 prefix_size,
png_alloc_size_t *newlength /* must be initialized to the maximum! */,
int terminate /*add a '\0' to the end of the uncompressed data*/)
{
/* TODO: implement different limits for different types of chunk.
*
* The caller supplies *newlength set to the maximum length of the
* uncompressed data, but this routine allocates space for the prefix and
* maybe a '\0' terminator too. We have to assume that 'prefix_size' is
* limited only by the maximum chunk size.
*/
png_alloc_size_t limit = PNG_SIZE_MAX;
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
if (limit >= prefix_size + (terminate != 0))
{
int ret;
limit -= prefix_size + (terminate != 0);
if (limit < *newlength)
*newlength = limit;
/* Now try to claim the stream. */
ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
if (ret == Z_OK)
{
png_uint_32 lzsize = chunklength - prefix_size;
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
/* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
/* output: */ NULL, newlength);
if (ret == Z_STREAM_END)
{
/* Use 'inflateReset' here, not 'inflateReset2' because this
* preserves the previously decided window size (otherwise it would
* be necessary to store the previous window size.) In practice
* this doesn't matter anyway, because png_inflate will call inflate
* with Z_FINISH in almost all cases, so the window will not be
* maintained.
*/
if (inflateReset(&png_ptr->zstream) == Z_OK)
{
/* Because of the limit checks above we know that the new,
* expanded, size will fit in a size_t (let alone an
* png_alloc_size_t). Use png_malloc_base here to avoid an
* extra OOM message.
*/
png_alloc_size_t new_size = *newlength;
png_alloc_size_t buffer_size = prefix_size + new_size +
(terminate != 0);
png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
buffer_size));
if (text != NULL)
{
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
png_ptr->read_buffer + prefix_size, &lzsize,
text + prefix_size, newlength);
if (ret == Z_STREAM_END)
{
if (new_size == *newlength)
{
if (terminate != 0)
text[prefix_size + *newlength] = 0;
if (prefix_size > 0)
memcpy(text, png_ptr->read_buffer, prefix_size);
{
png_bytep old_ptr = png_ptr->read_buffer;
png_ptr->read_buffer = text;
png_ptr->read_buffer_size = buffer_size;
text = old_ptr; /* freed below */
}
}
else
{
/* The size changed on the second read, there can be no
* guarantee that anything is correct at this point.
* The 'msg' pointer has been set to "unexpected end of
* LZ stream", which is fine, but return an error code
* that the caller won't accept.
*/
ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
else if (ret == Z_OK)
ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
/* Free the text pointer (this is the old read_buffer on
* success)
*/
png_free(png_ptr, text);
/* This really is very benign, but it's still an error because
* the extra space may otherwise be used as a Trojan Horse.
*/
if (ret == Z_STREAM_END &&
chunklength - prefix_size != lzsize)
png_chunk_benign_error(png_ptr, "extra compressed data");
}
else
{
/* Out of memory allocating the buffer */
ret = Z_MEM_ERROR;
png_zstream_error(png_ptr, Z_MEM_ERROR);
}
}
else
{
/* inflateReset failed, store the error message */
png_zstream_error(png_ptr, ret);
if (ret == Z_STREAM_END)
ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
else if (ret == Z_OK)
ret = PNG_UNEXPECTED_ZLIB_RETURN;
/* Release the claimed stream */
png_ptr->zowner = 0;
}
else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
ret = PNG_UNEXPECTED_ZLIB_RETURN;
return ret;
}
else
{
/* Application/configuration limits exceeded */
png_zstream_error(png_ptr, Z_MEM_ERROR);
return Z_MEM_ERROR;
}
}
#endif /* READ_COMPRESSED_TEXT */
#ifdef PNG_READ_iCCP_SUPPORTED
/* Perform a partial read and decompress, producing 'avail_out' bytes and
* reading from the current chunk as required.
*/
static int
png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
int finish)
{
if (png_ptr->zowner == png_ptr->chunk_name)
{
int ret;
/* next_in and avail_in must have been initialized by the caller. */
png_ptr->zstream.next_out = next_out;
png_ptr->zstream.avail_out = 0; /* set in the loop */
do
{
if (png_ptr->zstream.avail_in == 0)
{
if (read_size > *chunk_bytes)
read_size = (uInt)*chunk_bytes;
*chunk_bytes -= read_size;
if (read_size > 0)
png_crc_read(png_ptr, read_buffer, read_size);
png_ptr->zstream.next_in = read_buffer;
png_ptr->zstream.avail_in = read_size;
}
if (png_ptr->zstream.avail_out == 0)
{
uInt avail = ZLIB_IO_MAX;
if (avail > *out_size)
avail = (uInt)*out_size;
*out_size -= avail;
png_ptr->zstream.avail_out = avail;
}
/* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
* the available output is produced; this allows reading of truncated
* streams.
*/
ret = inflate(&png_ptr->zstream,
*chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
}
while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
*out_size += png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
/* Ensure the error message pointer is always set: */
png_zstream_error(png_ptr, ret);
return ret;
}
else
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
return Z_STREAM_ERROR;
}
}
#endif
/* Read and check the IDHR chunk */
void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[13];
png_uint_32 width, height;
int bit_depth, color_type, compression_type, filter_type;
int interlace_type;
png_debug(1, "in png_handle_IHDR");
if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
png_chunk_error(png_ptr, "out of place");
/* Check the length */
if (length != 13)
png_chunk_error(png_ptr, "invalid");
png_ptr->mode |= PNG_HAVE_IHDR;
png_crc_read(png_ptr, buf, 13);
png_crc_finish(png_ptr, 0);
width = png_get_uint_31(png_ptr, buf);
height = png_get_uint_31(png_ptr, buf + 4);
bit_depth = buf[8];
color_type = buf[9];
compression_type = buf[10];
filter_type = buf[11];
interlace_type = buf[12];
/* Set internal variables */
png_ptr->width = width;
png_ptr->height = height;
png_ptr->bit_depth = (png_byte)bit_depth;
png_ptr->interlaced = (png_byte)interlace_type;
png_ptr->color_type = (png_byte)color_type;
#ifdef PNG_MNG_FEATURES_SUPPORTED
png_ptr->filter_type = (png_byte)filter_type;
#endif
png_ptr->compression_type = (png_byte)compression_type;
/* Find number of channels */
switch (png_ptr->color_type)
{
default: /* invalid, png_set_IHDR calls png_error */
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_PALETTE:
png_ptr->channels = 1;
break;
case PNG_COLOR_TYPE_RGB:
png_ptr->channels = 3;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
png_ptr->channels = 2;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
png_ptr->channels = 4;
break;
}
/* Set up other useful info */
png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
png_debug1(3, "channels = %d", png_ptr->channels);
png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
color_type, interlace_type, compression_type, filter_type);
}
/* Read and check the palette */
void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_color palette[PNG_MAX_PALETTE_LENGTH];
int num, i;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
png_colorp pal_ptr;
#endif
png_debug(1, "in png_handle_PLTE");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
/* Moved to before the 'after IDAT' check below because otherwise duplicate
* PLTE chunks are potentially ignored (the spec says there shall not be more
* than one PLTE, the error is not treated as benign, so this check trumps
* the requirement that PLTE appears before IDAT.)
*/
else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
png_chunk_error(png_ptr, "duplicate");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
/* This is benign because the non-benign error happened before, when an
* IDAT was encountered in a color-mapped image with no PLTE.
*/
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
png_ptr->mode |= PNG_HAVE_PLTE;
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
return;
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
png_crc_finish(png_ptr, length);
return;
}
#endif
if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
{
png_crc_finish(png_ptr, length);
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
png_chunk_benign_error(png_ptr, "invalid");
else
png_chunk_error(png_ptr, "invalid");
return;
}
/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
num = (int)length / 3;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
pal_ptr->red = buf[0];
pal_ptr->green = buf[1];
pal_ptr->blue = buf[2];
}
#else
for (i = 0; i < num; i++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
/* Don't depend upon png_color being any order */
palette[i].red = buf[0];
palette[i].green = buf[1];
palette[i].blue = buf[2];
}
#endif
/* If we actually need the PLTE chunk (ie for a paletted image), we do
* whatever the normal CRC configuration tells us. However, if we
* have an RGB image, the PLTE can be considered ancillary, so
* we will act as though it is.
*/
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#endif
{
png_crc_finish(png_ptr, 0);
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
{
/* If we don't want to use the data from an ancillary chunk,
* we have two options: an error abort, or a warning and we
* ignore the data in this chunk (which should be OK, since
* it's considered ancillary for a RGB or RGBA image).
*
* IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
* chunk type to determine whether to check the ancillary or the critical
* flags.
*/
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
{
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
return;
else
png_chunk_error(png_ptr, "CRC error");
}
/* Otherwise, we (optionally) emit a warning and use the chunk. */
else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
png_chunk_warning(png_ptr, "CRC error");
}
#endif
/* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
* own copy of the palette. This has the side effect that when png_start_row
* is called (this happens after any call to png_read_update_info) the
* info_ptr palette gets changed. This is extremely unexpected and
* confusing.
*
* Fix this by not sharing the palette in this way.
*/
png_set_PLTE(png_ptr, info_ptr, palette, num);