forked from pnggroup/libpng
/
pngwutil.c
2784 lines (2291 loc) · 79.1 KB
/
pngwutil.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
/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.6.32 [August 24, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 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
*/
#include "pngpriv.h"
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
/* Place a 32-bit number into a buffer in PNG byte order. We work
* with unsigned numbers for convenience, although one supported
* ancillary chunk uses signed (two's complement) numbers.
*/
void PNGAPI
png_save_uint_32(png_bytep buf, png_uint_32 i)
{
buf[0] = (png_byte)((i >> 24) & 0xffU);
buf[1] = (png_byte)((i >> 16) & 0xffU);
buf[2] = (png_byte)((i >> 8) & 0xffU);
buf[3] = (png_byte)( i & 0xffU);
}
/* Place a 16-bit number into a buffer in PNG byte order.
* The parameter is declared unsigned int, not png_uint_16,
* just to avoid potential problems on pre-ANSI C compilers.
*/
void PNGAPI
png_save_uint_16(png_bytep buf, unsigned int i)
{
buf[0] = (png_byte)((i >> 8) & 0xffU);
buf[1] = (png_byte)( i & 0xffU);
}
#endif
/* Simple function to write the signature. If we have already written
* the magic bytes of the signature, or more likely, the PNG stream is
* being embedded into another stream and doesn't need its own signature,
* we should call png_set_sig_bytes() to tell libpng how many of the
* bytes have already been written.
*/
void PNGAPI
png_write_sig(png_structrp png_ptr)
{
png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the signature is being written */
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
#endif
/* Write the rest of the 8 byte signature */
png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
(png_size_t)(8 - png_ptr->sig_bytes));
if (png_ptr->sig_bytes < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Write the start of a PNG chunk. The type is the chunk type.
* The total_length is the sum of the lengths of all the data you will be
* passing in png_write_chunk_data().
*/
static void
png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
png_uint_32 length)
{
png_byte buf[8];
#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
#endif
if (png_ptr == NULL)
return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk header is being written.
* PNG_IO_CHUNK_HDR requires a single I/O call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
#endif
/* Write the length and the chunk name */
png_save_uint_32(buf, length);
png_save_uint_32(buf + 4, chunk_name);
png_write_data(png_ptr, buf, 8);
/* Put the chunk name into png_ptr->chunk_name */
png_ptr->chunk_name = chunk_name;
/* Reset the crc and run it over the chunk name */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that chunk data will (possibly) be written.
* PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
#endif
}
void PNGAPI
png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
png_uint_32 length)
{
png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
}
/* Write the data of a PNG chunk started with png_write_chunk_header().
* Note that multiple calls to this function are allowed, and that the
* sum of the lengths from these calls *must* add up to the total_length
* given to png_write_chunk_header().
*/
void PNGAPI
png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
png_size_t length)
{
/* Write the data, and run the CRC over it */
if (png_ptr == NULL)
return;
if (data != NULL && length > 0)
{
png_write_data(png_ptr, data, length);
/* Update the CRC after writing the data,
* in case the user I/O routine alters it.
*/
png_calculate_crc(png_ptr, data, length);
}
}
/* Finish a chunk started with png_write_chunk_header(). */
void PNGAPI
png_write_chunk_end(png_structrp png_ptr)
{
png_byte buf[4];
if (png_ptr == NULL) return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk CRC is being written.
* PNG_IO_CHUNK_CRC requires a single I/O function call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
#endif
/* Write the crc in a single operation */
png_save_uint_32(buf, png_ptr->crc);
png_write_data(png_ptr, buf, (png_size_t)4);
}
/* Write a PNG chunk all at once. The type is an array of ASCII characters
* representing the chunk name. The array must be at least 4 bytes in
* length, and does not need to be null terminated. To be safe, pass the
* pre-defined chunk names here, and if you need a new one, define it
* where the others are defined. The length is the length of the data.
* All the data must be present. If that is not possible, use the
* png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
* functions instead.
*/
static void
png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
png_const_bytep data, png_size_t length)
{
if (png_ptr == NULL)
return;
/* On 64-bit architectures 'length' may not fit in a png_uint_32. */
if (length > PNG_UINT_31_MAX)
png_error(png_ptr, "length exceeds PNG maximum");
png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
png_write_chunk_data(png_ptr, data, length);
png_write_chunk_end(png_ptr);
}
/* This is the API that calls the internal function above. */
void PNGAPI
png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
png_const_bytep data, png_size_t length)
{
png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
length);
}
/* This is used below to find the size of an image to pass to png_deflate_claim,
* so it only needs to be accurate if the size is less than 16384 bytes (the
* point at which a lower LZ window size can be used.)
*/
static png_alloc_size_t
png_image_size(png_structrp png_ptr)
{
/* Only return sizes up to the maximum of a png_uint_32; do this by limiting
* the width and height used to 15 bits.
*/
png_uint_32 h = png_ptr->height;
if (png_ptr->rowbytes < 32768 && h < 32768)
{
if (png_ptr->interlaced != 0)
{
/* Interlacing makes the image larger because of the replication of
* both the filter byte and the padding to a byte boundary.
*/
png_uint_32 w = png_ptr->width;
unsigned int pd = png_ptr->pixel_depth;
png_alloc_size_t cb_base;
int pass;
for (cb_base=0, pass=0; pass<=6; ++pass)
{
png_uint_32 pw = PNG_PASS_COLS(w, pass);
if (pw > 0)
cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
}
return cb_base;
}
else
return (png_ptr->rowbytes+1) * h;
}
else
return 0xffffffffU;
}
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* This is the code to hack the first two bytes of the deflate stream (the
* deflate header) to correct the windowBits value to match the actual data
* size. Note that the second argument is the *uncompressed* size but the
* first argument is the *compressed* data (and it must be deflate
* compressed.)
*/
static void
optimize_cmf(png_bytep data, png_alloc_size_t data_size)
{
/* Optimize the CMF field in the zlib stream. The resultant zlib stream is
* still compliant to the stream specification.
*/
if (data_size <= 16384) /* else windowBits must be 15 */
{
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
unsigned int z_cinfo;
unsigned int half_z_window_size;
z_cinfo = z_cmf >> 4;
half_z_window_size = 1U << (z_cinfo + 7);
if (data_size <= half_z_window_size) /* else no change */
{
unsigned int tmp;
do
{
half_z_window_size >>= 1;
--z_cinfo;
}
while (z_cinfo > 0 && data_size <= half_z_window_size);
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
data[0] = (png_byte)z_cmf;
tmp = data[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
data[1] = (png_byte)tmp;
}
}
}
}
#endif /* WRITE_OPTIMIZE_CMF */
/* Initialize the compressor for the appropriate type of compression. */
static int
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
png_alloc_size_t data_size)
{
if (png_ptr->zowner != 0)
{
#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
char msg[64];
PNG_STRING_FROM_CHUNK(msg, owner);
msg[4] = ':';
msg[5] = ' ';
PNG_STRING_FROM_CHUNK(msg+6, 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), 10, " using zstream");
#endif
#if PNG_RELEASE_BUILD
png_warning(png_ptr, msg);
/* Attempt sane error recovery */
if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
return Z_STREAM_ERROR;
}
png_ptr->zowner = 0;
#else
png_error(png_ptr, msg);
#endif
}
{
int level = png_ptr->zlib_level;
int method = png_ptr->zlib_method;
int windowBits = png_ptr->zlib_window_bits;
int memLevel = png_ptr->zlib_mem_level;
int strategy; /* set below */
int ret; /* zlib return code */
if (owner == png_IDAT)
{
if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
strategy = png_ptr->zlib_strategy;
else if (png_ptr->do_filter != PNG_FILTER_NONE)
strategy = PNG_Z_DEFAULT_STRATEGY;
else
strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
}
else
{
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
level = png_ptr->zlib_text_level;
method = png_ptr->zlib_text_method;
windowBits = png_ptr->zlib_text_window_bits;
memLevel = png_ptr->zlib_text_mem_level;
strategy = png_ptr->zlib_text_strategy;
#else
/* If customization is not supported the values all come from the
* IDAT values except for the strategy, which is fixed to the
* default. (This is the pre-1.6.0 behavior too, although it was
* implemented in a very different way.)
*/
strategy = Z_DEFAULT_STRATEGY;
#endif
}
/* Adjust 'windowBits' down if larger than 'data_size'; to stop this
* happening just pass 32768 as the data_size parameter. Notice that zlib
* requires an extra 262 bytes in the window in addition to the data to be
* able to see the whole of the data, so if data_size+262 takes us to the
* next windowBits size we need to fix up the value later. (Because even
* though deflate needs the extra window, inflate does not!)
*/
if (data_size <= 16384)
{
/* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
* work round a Microsoft Visual C misbehavior which, contrary to C-90,
* widens the result of the following shift to 64-bits if (and,
* apparently, only if) it is used in a test.
*/
unsigned int half_window_size = 1U << (windowBits-1);
while (data_size + 262 <= half_window_size)
{
half_window_size >>= 1;
--windowBits;
}
}
/* Check against the previous initialized values, if any. */
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
(png_ptr->zlib_set_level != level ||
png_ptr->zlib_set_method != method ||
png_ptr->zlib_set_window_bits != windowBits ||
png_ptr->zlib_set_mem_level != memLevel ||
png_ptr->zlib_set_strategy != strategy))
{
if (deflateEnd(&png_ptr->zstream) != Z_OK)
png_warning(png_ptr, "deflateEnd failed (ignored)");
png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
}
/* For safety clear out the input and output pointers (currently zlib
* doesn't use them on Init, but it might in the future).
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
/* Now initialize if required, setting the new parameters, otherwise just
* do a simple reset to the previous parameters.
*/
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
ret = deflateReset(&png_ptr->zstream);
else
{
ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
memLevel, strategy);
if (ret == Z_OK)
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
}
/* The return code is from either deflateReset or deflateInit2; they have
* pretty much the same set of error codes.
*/
if (ret == Z_OK)
png_ptr->zowner = owner;
else
png_zstream_error(png_ptr, ret);
return ret;
}
}
/* Clean up (or trim) a linked list of compression buffers. */
void /* PRIVATE */
png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
{
png_compression_bufferp list = *listp;
if (list != NULL)
{
*listp = NULL;
do
{
png_compression_bufferp next = list->next;
png_free(png_ptr, list);
list = next;
}
while (list != NULL);
}
}
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
/* This pair of functions encapsulates the operation of (a) compressing a
* text string, and (b) issuing it later as a series of chunk data writes.
* The compression_state structure is shared context for these functions
* set up by the caller to allow access to the relevant local variables.
*
* compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
* temporary buffers. From 1.6.0 it is retained in png_struct so that it will
* be correctly freed in the event of a write error (previous implementations
* just leaked memory.)
*/
typedef struct
{
png_const_bytep input; /* The uncompressed input data */
png_alloc_size_t input_len; /* Its length */
png_uint_32 output_len; /* Final compressed length */
png_byte output[1024]; /* First block of output */
} compression_state;
static void
png_text_compress_init(compression_state *comp, png_const_bytep input,
png_alloc_size_t input_len)
{
comp->input = input;
comp->input_len = input_len;
comp->output_len = 0;
}
/* Compress the data in the compression state input */
static int
png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
compression_state *comp, png_uint_32 prefix_len)
{
int ret;
/* To find the length of the output it is necessary to first compress the
* input. The result is buffered rather than using the two-pass algorithm
* that is used on the inflate side; deflate is assumed to be slower and a
* PNG writer is assumed to have more memory available than a PNG reader.
*
* IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
* upper limit on the output size, but it is always bigger than the input
* size so it is likely to be more efficient to use this linked-list
* approach.
*/
ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
if (ret != Z_OK)
return ret;
/* Set up the compression buffers, we need a loop here to avoid overflowing a
* uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
* by the output buffer size, so there is no need to check that. Since this
* is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
* in size.
*/
{
png_compression_bufferp *end = &png_ptr->zbuffer_list;
png_alloc_size_t input_len = comp->input_len; /* may be zero! */
png_uint_32 output_len;
/* zlib updates these for us: */
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
png_ptr->zstream.avail_in = 0; /* Set below */
png_ptr->zstream.next_out = comp->output;
png_ptr->zstream.avail_out = (sizeof comp->output);
output_len = png_ptr->zstream.avail_out;
do
{
uInt avail_in = ZLIB_IO_MAX;
if (avail_in > input_len)
avail_in = (uInt)input_len;
input_len -= avail_in;
png_ptr->zstream.avail_in = avail_in;
if (png_ptr->zstream.avail_out == 0)
{
png_compression_buffer *next;
/* Chunk data is limited to 2^31 bytes in length, so the prefix
* length must be counted here.
*/
if (output_len + prefix_len > PNG_UINT_31_MAX)
{
ret = Z_MEM_ERROR;
break;
}
/* Need a new (malloc'ed) buffer, but there may be one present
* already.
*/
next = *end;
if (next == NULL)
{
next = png_voidcast(png_compression_bufferp, png_malloc_base
(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
if (next == NULL)
{
ret = Z_MEM_ERROR;
break;
}
/* Link in this buffer (so that it will be freed later) */
next->next = NULL;
*end = next;
}
png_ptr->zstream.next_out = next->output;
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
output_len += png_ptr->zstream.avail_out;
/* Move 'end' to the next buffer pointer. */
end = &next->next;
}
/* Compress the data */
ret = deflate(&png_ptr->zstream,
input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
/* Claw back input data that was not consumed (because avail_in is
* reset above every time round the loop).
*/
input_len += png_ptr->zstream.avail_in;
png_ptr->zstream.avail_in = 0; /* safety */
}
while (ret == Z_OK);
/* There may be some space left in the last output buffer. This needs to
* be subtracted from output_len.
*/
output_len -= png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0; /* safety */
comp->output_len = output_len;
/* Now double check the output length, put in a custom message if it is
* too long. Otherwise ensure the z_stream::msg pointer is set to
* something.
*/
if (output_len + prefix_len >= PNG_UINT_31_MAX)
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
ret = Z_MEM_ERROR;
}
else
png_zstream_error(png_ptr, ret);
/* Reset zlib for another zTXt/iTXt or image data */
png_ptr->zowner = 0;
/* The only success case is Z_STREAM_END, input_len must be 0; if not this
* is an internal error.
*/
if (ret == Z_STREAM_END && input_len == 0)
{
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* Fix up the deflate header, if required */
optimize_cmf(comp->output, comp->input_len);
#endif
/* But Z_OK is returned, not Z_STREAM_END; this allows the claim
* function above to return Z_STREAM_END on an error (though it never
* does in the current versions of zlib.)
*/
return Z_OK;
}
else
return ret;
}
}
/* Ship the compressed text out via chunk writes */
static void
png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
{
png_uint_32 output_len = comp->output_len;
png_const_bytep output = comp->output;
png_uint_32 avail = (sizeof comp->output);
png_compression_buffer *next = png_ptr->zbuffer_list;
for (;;)
{
if (avail > output_len)
avail = output_len;
png_write_chunk_data(png_ptr, output, avail);
output_len -= avail;
if (output_len == 0 || next == NULL)
break;
avail = png_ptr->zbuffer_size;
output = next->output;
next = next->next;
}
/* This is an internal error; 'next' must have been NULL! */
if (output_len > 0)
png_error(png_ptr, "error writing ancillary chunked compressed data");
}
#endif /* WRITE_COMPRESSED_TEXT */
/* Write the IHDR chunk, and update the png_struct with the necessary
* information. Note that the rest of this code depends upon this
* information being correct.
*/
void /* PRIVATE */
png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
int bit_depth, int color_type, int compression_type, int filter_type,
int interlace_type)
{
png_byte buf[13]; /* Buffer to store the IHDR info */
int is_invalid_depth;
png_debug(1, "in png_write_IHDR");
/* Check that we have valid input data from the application info */
switch (color_type)
{
case PNG_COLOR_TYPE_GRAY:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
#ifdef PNG_WRITE_16BIT_SUPPORTED
case 16:
#endif
png_ptr->channels = 1; break;
default:
png_error(png_ptr,
"Invalid bit depth for grayscale image");
}
break;
case PNG_COLOR_TYPE_RGB:
is_invalid_depth = (bit_depth != 8);
#ifdef PNG_WRITE_16BIT_SUPPORTED
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
#endif
if (is_invalid_depth)
png_error(png_ptr, "Invalid bit depth for RGB image");
png_ptr->channels = 3;
break;
case PNG_COLOR_TYPE_PALETTE:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
png_ptr->channels = 1;
break;
default:
png_error(png_ptr, "Invalid bit depth for paletted image");
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
is_invalid_depth = (bit_depth != 8);
#ifdef PNG_WRITE_16BIT_SUPPORTED
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
#endif
if (is_invalid_depth)
png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
png_ptr->channels = 2;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
is_invalid_depth = (bit_depth != 8);
#ifdef PNG_WRITE_16BIT_SUPPORTED
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
#endif
if (is_invalid_depth)
png_error(png_ptr, "Invalid bit depth for RGBA image");
png_ptr->channels = 4;
break;
default:
png_error(png_ptr, "Invalid image color type specified");
}
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
{
png_warning(png_ptr, "Invalid compression type specified");
compression_type = PNG_COMPRESSION_TYPE_BASE;
}
/* Write filter_method 64 (intrapixel differencing) only if
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
* 2. Libpng did not write a PNG signature (this filter_method is only
* used in PNG datastreams that are embedded in MNG datastreams) and
* 3. The application called png_permit_mng_features with a mask that
* included PNG_FLAG_MNG_FILTER_64 and
* 4. The filter_method is 64 and
* 5. The color_type is RGB or RGBA
*/
if (
#ifdef PNG_MNG_FEATURES_SUPPORTED
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
(color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
(filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
#endif
filter_type != PNG_FILTER_TYPE_BASE)
{
png_warning(png_ptr, "Invalid filter type specified");
filter_type = PNG_FILTER_TYPE_BASE;
}
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
if (interlace_type != PNG_INTERLACE_NONE &&
interlace_type != PNG_INTERLACE_ADAM7)
{
png_warning(png_ptr, "Invalid interlace type specified");
interlace_type = PNG_INTERLACE_ADAM7;
}
#else
interlace_type=PNG_INTERLACE_NONE;
#endif
/* Save the relevant information */
png_ptr->bit_depth = (png_byte)bit_depth;
png_ptr->color_type = (png_byte)color_type;
png_ptr->interlaced = (png_byte)interlace_type;
#ifdef PNG_MNG_FEATURES_SUPPORTED
png_ptr->filter_type = (png_byte)filter_type;
#endif
png_ptr->compression_type = (png_byte)compression_type;
png_ptr->width = width;
png_ptr->height = height;
png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
/* Set the usr info, so any transformations can modify it */
png_ptr->usr_width = png_ptr->width;
png_ptr->usr_bit_depth = png_ptr->bit_depth;
png_ptr->usr_channels = png_ptr->channels;
/* Pack the header information into the buffer */
png_save_uint_32(buf, width);
png_save_uint_32(buf + 4, height);
buf[8] = (png_byte)bit_depth;
buf[9] = (png_byte)color_type;
buf[10] = (png_byte)compression_type;
buf[11] = (png_byte)filter_type;
buf[12] = (png_byte)interlace_type;
/* Write the chunk */
png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
if ((png_ptr->do_filter) == PNG_NO_FILTERS)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
png_ptr->bit_depth < 8)
png_ptr->do_filter = PNG_FILTER_NONE;
else
png_ptr->do_filter = PNG_ALL_FILTERS;
}
png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
}
/* Write the palette. We are careful not to trust png_color to be in the
* correct order for PNG, so people can redefine it to any convenient
* structure.
*/
void /* PRIVATE */
png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
png_uint_32 num_pal)
{
png_uint_32 max_palette_length, i;
png_const_colorp pal_ptr;
png_byte buf[3];
png_debug(1, "in png_write_PLTE");
max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
if ((
#ifdef PNG_MNG_FEATURES_SUPPORTED
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
#endif
num_pal == 0) || num_pal > max_palette_length)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
png_error(png_ptr, "Invalid number of colors in palette");
}
else
{
png_warning(png_ptr, "Invalid number of colors in palette");
return;
}
}
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
{
png_warning(png_ptr,
"Ignoring request to write a PLTE chunk in grayscale PNG");
return;
}
png_ptr->num_palette = (png_uint_16)num_pal;
png_debug1(3, "num_palette = %d", png_ptr->num_palette);
png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
{
buf[0] = pal_ptr->red;
buf[1] = pal_ptr->green;
buf[2] = pal_ptr->blue;
png_write_chunk_data(png_ptr, buf, (png_size_t)3);
}
#else
/* This is a little slower but some buggy compilers need to do this
* instead
*/
pal_ptr=palette;
for (i = 0; i < num_pal; i++)
{
buf[0] = pal_ptr[i].red;
buf[1] = pal_ptr[i].green;
buf[2] = pal_ptr[i].blue;
png_write_chunk_data(png_ptr, buf, (png_size_t)3);
}
#endif
png_write_chunk_end(png_ptr);
png_ptr->mode |= PNG_HAVE_PLTE;
}
/* This is similar to png_text_compress, above, except that it does not require
* all of the data at once and, instead of buffering the compressed result,
* writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
* because it calls the write interface. As a result it does its own error
* reporting and does not return an error code. In the event of error it will
* just call png_error. The input data length may exceed 32-bits. The 'flush'
* parameter is exactly the same as that to deflate, with the following
* meanings:
*
* Z_NO_FLUSH: normal incremental output of compressed data
* Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
* Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
*
* The routine manages the acquire and release of the png_ptr->zstream by
* checking and (at the end) clearing png_ptr->zowner; it does some sanity
* checks on the 'mode' flags while doing this.
*/
void /* PRIVATE */
png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
png_alloc_size_t input_len, int flush)
{
if (png_ptr->zowner != png_IDAT)
{
/* First time. Ensure we have a temporary buffer for compression and
* trim the buffer list if it has more than one entry to free memory.
* If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
* created at this point, but the check here is quick and safe.
*/
if (png_ptr->zbuffer_list == NULL)
{
png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
png_ptr->zbuffer_list->next = NULL;
}
else
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
/* It is a terminal error if we can't claim the zstream. */
if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
/* The output state is maintained in png_ptr->zstream, so it must be
* initialized here after the claim.
*/
png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
}
/* Now loop reading and writing until all the input is consumed or an error
* terminates the operation. The _out values are maintained across calls to
* this function, but the input must be reset each time.
*/
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
png_ptr->zstream.avail_in = 0; /* set below */
for (;;)
{
int ret;
/* INPUT: from the row data */
uInt avail = ZLIB_IO_MAX;
if (avail > input_len)
avail = (uInt)input_len; /* safe because of the check */
png_ptr->zstream.avail_in = avail;
input_len -= avail;
ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
/* Include as-yet unconsumed input */
input_len += png_ptr->zstream.avail_in;
png_ptr->zstream.avail_in = 0;
/* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
* that these two zstream fields are preserved across the calls, therefore
* there is no need to set these up on entry to the loop.
*/
if (png_ptr->zstream.avail_out == 0)
{
png_bytep data = png_ptr->zbuffer_list->output;
uInt size = png_ptr->zbuffer_size;
/* Write an IDAT containing the data then reset the buffer. The
* first IDAT may need deflate header optimization.
*/
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED