1
2/* pngpread.c - read a png file in push mode
3 *
4 * Last changed in libpng 1.6.18 [July 23, 2015]
5 * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14#include "pngpriv.h"
15
16#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
17
18/* Push model modes */
19#define PNG_READ_SIG_MODE 0
20#define PNG_READ_CHUNK_MODE 1
21#define PNG_READ_IDAT_MODE 2
22#define PNG_READ_tEXt_MODE 4
23#define PNG_READ_zTXt_MODE 5
24#define PNG_READ_DONE_MODE 6
25#define PNG_READ_iTXt_MODE 7
26#define PNG_ERROR_MODE 8
27
28#define PNG_PUSH_SAVE_BUFFER_IF_FULL \
29if (png_ptr->push_length + 4 > png_ptr->buffer_size) \
30 { png_push_save_buffer(png_ptr); return; }
31#define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \
32if (png_ptr->buffer_size < N) \
33 { png_push_save_buffer(png_ptr); return; }
34
35void PNGAPI
36png_process_data(png_structrp png_ptr, png_inforp info_ptr,
37 png_bytep buffer, png_size_t buffer_size)
38{
39 if (png_ptr == NULL || info_ptr == NULL)
40 return;
41
42 png_push_restore_buffer(png_ptr, buffer, buffer_size);
43
44 while (png_ptr->buffer_size)
45 {
46 png_process_some_data(png_ptr, info_ptr);
47 }
48}
49
50png_size_t PNGAPI
51png_process_data_pause(png_structrp png_ptr, int save)
52{
53 if (png_ptr != NULL)
54 {
55 /* It's easiest for the caller if we do the save; then the caller doesn't
56 * have to supply the same data again:
57 */
58 if (save != 0)
59 png_push_save_buffer(png_ptr);
60 else
61 {
62 /* This includes any pending saved bytes: */
63 png_size_t remaining = png_ptr->buffer_size;
64 png_ptr->buffer_size = 0;
65
66 /* So subtract the saved buffer size, unless all the data
67 * is actually 'saved', in which case we just return 0
68 */
69 if (png_ptr->save_buffer_size < remaining)
70 return remaining - png_ptr->save_buffer_size;
71 }
72 }
73
74 return 0;
75}
76
77png_uint_32 PNGAPI
78png_process_data_skip(png_structrp png_ptr)
79{
80 /* TODO: Deprecate and remove this API.
81 * Somewhere the implementation of this seems to have been lost,
82 * or abandoned. It was only to support some internal back-door access
83 * to png_struct) in libpng-1.4.x.
84 */
85 png_app_warning(png_ptr,
86"png_process_data_skip is not implemented in any current version of libpng");
87 return 0;
88}
89
90/* What we do with the incoming data depends on what we were previously
91 * doing before we ran out of data...
92 */
93void /* PRIVATE */
94png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
95{
96 if (png_ptr == NULL)
97 return;
98
99 switch (png_ptr->process_mode)
100 {
101 case PNG_READ_SIG_MODE:
102 {
103 png_push_read_sig(png_ptr, info_ptr);
104 break;
105 }
106
107 case PNG_READ_CHUNK_MODE:
108 {
109 png_push_read_chunk(png_ptr, info_ptr);
110 break;
111 }
112
113 case PNG_READ_IDAT_MODE:
114 {
115 png_push_read_IDAT(png_ptr);
116 break;
117 }
118
119 default:
120 {
121 png_ptr->buffer_size = 0;
122 break;
123 }
124 }
125}
126
127/* Read any remaining signature bytes from the stream and compare them with
128 * the correct PNG signature. It is possible that this routine is called
129 * with bytes already read from the signature, either because they have been
130 * checked by the calling application, or because of multiple calls to this
131 * routine.
132 */
133void /* PRIVATE */
134png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
135{
136 png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
137 num_to_check = 8 - num_checked;
138
139 if (png_ptr->buffer_size < num_to_check)
140 {
141 num_to_check = png_ptr->buffer_size;
142 }
143
144 png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
145 num_to_check);
146 png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
147
148 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
149 {
150 if (num_checked < 4 &&
151 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
152 png_error(png_ptr, "Not a PNG file");
153
154 else
155 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
156 }
157 else
158 {
159 if (png_ptr->sig_bytes >= 8)
160 {
161 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
162 }
163 }
164}
165
166void /* PRIVATE */
167png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
168{
169 png_uint_32 chunk_name;
170#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
171 int keep; /* unknown handling method */
172#endif
173
174 /* First we make sure we have enough data for the 4-byte chunk name
175 * and the 4-byte chunk length before proceeding with decoding the
176 * chunk data. To fully decode each of these chunks, we also make
177 * sure we have enough data in the buffer for the 4-byte CRC at the
178 * end of every chunk (except IDAT, which is handled separately).
179 */
180 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
181 {
182 png_byte chunk_length[4];
183 png_byte chunk_tag[4];
184
185 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
186 png_push_fill_buffer(png_ptr, chunk_length, 4);
187 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
188 png_reset_crc(png_ptr);
189 png_crc_read(png_ptr, chunk_tag, 4);
190 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
191 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
192 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
193 }
194
195 chunk_name = png_ptr->chunk_name;
196
197 if (chunk_name == png_IDAT)
198 {
199 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
200 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
201
202 /* If we reach an IDAT chunk, this means we have read all of the
203 * header chunks, and we can start reading the image (or if this
204 * is called after the image has been read - we have an error).
205 */
206 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
207 png_error(png_ptr, "Missing IHDR before IDAT");
208
209 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
210 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
211 png_error(png_ptr, "Missing PLTE before IDAT");
212
213 png_ptr->mode |= PNG_HAVE_IDAT;
214 png_ptr->process_mode = PNG_READ_IDAT_MODE;
215
216 if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
217 if (png_ptr->push_length == 0)
218 return;
219
220 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
221 png_benign_error(png_ptr, "Too many IDATs found");
222 }
223
224 if (chunk_name == png_IHDR)
225 {
226 if (png_ptr->push_length != 13)
227 png_error(png_ptr, "Invalid IHDR length");
228
229 PNG_PUSH_SAVE_BUFFER_IF_FULL
230 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
231 }
232
233 else if (chunk_name == png_IEND)
234 {
235 PNG_PUSH_SAVE_BUFFER_IF_FULL
236 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
237
238 png_ptr->process_mode = PNG_READ_DONE_MODE;
239 png_push_have_end(png_ptr, info_ptr);
240 }
241
242#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
243 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
244 {
245 PNG_PUSH_SAVE_BUFFER_IF_FULL
246 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
247
248 if (chunk_name == png_PLTE)
249 png_ptr->mode |= PNG_HAVE_PLTE;
250 }
251#endif
252
253 else if (chunk_name == png_PLTE)
254 {
255 PNG_PUSH_SAVE_BUFFER_IF_FULL
256 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
257 }
258
259 else if (chunk_name == png_IDAT)
260 {
261 png_ptr->idat_size = png_ptr->push_length;
262 png_ptr->process_mode = PNG_READ_IDAT_MODE;
263 png_push_have_info(png_ptr, info_ptr);
264 png_ptr->zstream.avail_out =
265 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
266 png_ptr->iwidth) + 1;
267 png_ptr->zstream.next_out = png_ptr->row_buf;
268 return;
269 }
270
271#ifdef PNG_READ_gAMA_SUPPORTED
272 else if (png_ptr->chunk_name == png_gAMA)
273 {
274 PNG_PUSH_SAVE_BUFFER_IF_FULL
275 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
276 }
277
278#endif
279#ifdef PNG_READ_sBIT_SUPPORTED
280 else if (png_ptr->chunk_name == png_sBIT)
281 {
282 PNG_PUSH_SAVE_BUFFER_IF_FULL
283 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
284 }
285
286#endif
287#ifdef PNG_READ_cHRM_SUPPORTED
288 else if (png_ptr->chunk_name == png_cHRM)
289 {
290 PNG_PUSH_SAVE_BUFFER_IF_FULL
291 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
292 }
293
294#endif
295#ifdef PNG_READ_sRGB_SUPPORTED
296 else if (chunk_name == png_sRGB)
297 {
298 PNG_PUSH_SAVE_BUFFER_IF_FULL
299 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
300 }
301
302#endif
303#ifdef PNG_READ_iCCP_SUPPORTED
304 else if (png_ptr->chunk_name == png_iCCP)
305 {
306 PNG_PUSH_SAVE_BUFFER_IF_FULL
307 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
308 }
309
310#endif
311#ifdef PNG_READ_sPLT_SUPPORTED
312 else if (chunk_name == png_sPLT)
313 {
314 PNG_PUSH_SAVE_BUFFER_IF_FULL
315 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
316 }
317
318#endif
319#ifdef PNG_READ_tRNS_SUPPORTED
320 else if (chunk_name == png_tRNS)
321 {
322 PNG_PUSH_SAVE_BUFFER_IF_FULL
323 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
324 }
325
326#endif
327#ifdef PNG_READ_bKGD_SUPPORTED
328 else if (chunk_name == png_bKGD)
329 {
330 PNG_PUSH_SAVE_BUFFER_IF_FULL
331 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
332 }
333
334#endif
335#ifdef PNG_READ_hIST_SUPPORTED
336 else if (chunk_name == png_hIST)
337 {
338 PNG_PUSH_SAVE_BUFFER_IF_FULL
339 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
340 }
341
342#endif
343#ifdef PNG_READ_pHYs_SUPPORTED
344 else if (chunk_name == png_pHYs)
345 {
346 PNG_PUSH_SAVE_BUFFER_IF_FULL
347 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
348 }
349
350#endif
351#ifdef PNG_READ_oFFs_SUPPORTED
352 else if (chunk_name == png_oFFs)
353 {
354 PNG_PUSH_SAVE_BUFFER_IF_FULL
355 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
356 }
357#endif
358
359#ifdef PNG_READ_pCAL_SUPPORTED
360 else if (chunk_name == png_pCAL)
361 {
362 PNG_PUSH_SAVE_BUFFER_IF_FULL
363 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
364 }
365
366#endif
367#ifdef PNG_READ_sCAL_SUPPORTED
368 else if (chunk_name == png_sCAL)
369 {
370 PNG_PUSH_SAVE_BUFFER_IF_FULL
371 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
372 }
373
374#endif
375#ifdef PNG_READ_tIME_SUPPORTED
376 else if (chunk_name == png_tIME)
377 {
378 PNG_PUSH_SAVE_BUFFER_IF_FULL
379 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
380 }
381
382#endif
383#ifdef PNG_READ_tEXt_SUPPORTED
384 else if (chunk_name == png_tEXt)
385 {
386 PNG_PUSH_SAVE_BUFFER_IF_FULL
387 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
388 }
389
390#endif
391#ifdef PNG_READ_zTXt_SUPPORTED
392 else if (chunk_name == png_zTXt)
393 {
394 PNG_PUSH_SAVE_BUFFER_IF_FULL
395 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
396 }
397
398#endif
399#ifdef PNG_READ_iTXt_SUPPORTED
400 else if (chunk_name == png_iTXt)
401 {
402 PNG_PUSH_SAVE_BUFFER_IF_FULL
403 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
404 }
405#endif
406
407 else
408 {
409 PNG_PUSH_SAVE_BUFFER_IF_FULL
410 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
411 PNG_HANDLE_CHUNK_AS_DEFAULT);
412 }
413
414 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
415}
416
417void PNGCBAPI
418png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
419{
420 png_bytep ptr;
421
422 if (png_ptr == NULL)
423 return;
424
425 ptr = buffer;
426 if (png_ptr->save_buffer_size != 0)
427 {
428 png_size_t save_size;
429
430 if (length < png_ptr->save_buffer_size)
431 save_size = length;
432
433 else
434 save_size = png_ptr->save_buffer_size;
435
436 memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
437 length -= save_size;
438 ptr += save_size;
439 png_ptr->buffer_size -= save_size;
440 png_ptr->save_buffer_size -= save_size;
441 png_ptr->save_buffer_ptr += save_size;
442 }
443 if (length != 0 && png_ptr->current_buffer_size != 0)
444 {
445 png_size_t save_size;
446
447 if (length < png_ptr->current_buffer_size)
448 save_size = length;
449
450 else
451 save_size = png_ptr->current_buffer_size;
452
453 memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
454 png_ptr->buffer_size -= save_size;
455 png_ptr->current_buffer_size -= save_size;
456 png_ptr->current_buffer_ptr += save_size;
457 }
458}
459
460void /* PRIVATE */
461png_push_save_buffer(png_structrp png_ptr)
462{
463 if (png_ptr->save_buffer_size != 0)
464 {
465 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
466 {
467 png_size_t i, istop;
468 png_bytep sp;
469 png_bytep dp;
470
471 istop = png_ptr->save_buffer_size;
472 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
473 i < istop; i++, sp++, dp++)
474 {
475 *dp = *sp;
476 }
477 }
478 }
479 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
480 png_ptr->save_buffer_max)
481 {
482 png_size_t new_max;
483 png_bytep old_buffer;
484
485 if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
486 (png_ptr->current_buffer_size + 256))
487 {
488 png_error(png_ptr, "Potential overflow of save_buffer");
489 }
490
491 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
492 old_buffer = png_ptr->save_buffer;
493 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
494 (png_size_t)new_max);
495
496 if (png_ptr->save_buffer == NULL)
497 {
498 png_free(png_ptr, old_buffer);
499 png_error(png_ptr, "Insufficient memory for save_buffer");
500 }
501
502#if 0
503 // This is the code checked into libpng. Calling memcpy with a null
504 // source is undefined, even if count is 0, but libpng does not
505 // currently check for null or 0. The Skia fix is below.
506 // skbug.com/5390
507 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
508#else
509 if (old_buffer)
510 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
511 else if (png_ptr->save_buffer_size)
512 png_error(png_ptr, "save_buffer error");
513#endif
514 png_free(png_ptr, old_buffer);
515 png_ptr->save_buffer_max = new_max;
516 }
517 if (png_ptr->current_buffer_size)
518 {
519 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
520 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
521 png_ptr->save_buffer_size += png_ptr->current_buffer_size;
522 png_ptr->current_buffer_size = 0;
523 }
524 png_ptr->save_buffer_ptr = png_ptr->save_buffer;
525 png_ptr->buffer_size = 0;
526}
527
528void /* PRIVATE */
529png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
530 png_size_t buffer_length)
531{
532 png_ptr->current_buffer = buffer;
533 png_ptr->current_buffer_size = buffer_length;
534 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
535 png_ptr->current_buffer_ptr = png_ptr->current_buffer;
536}
537
538void /* PRIVATE */
539png_push_read_IDAT(png_structrp png_ptr)
540{
541 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
542 {
543 png_byte chunk_length[4];
544 png_byte chunk_tag[4];
545
546 /* TODO: this code can be commoned up with the same code in push_read */
547 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
548 png_push_fill_buffer(png_ptr, chunk_length, 4);
549 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
550 png_reset_crc(png_ptr);
551 png_crc_read(png_ptr, chunk_tag, 4);
552 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
553 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
554
555 if (png_ptr->chunk_name != png_IDAT)
556 {
557 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
558
559 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
560 png_error(png_ptr, "Not enough compressed data");
561
562 return;
563 }
564
565 png_ptr->idat_size = png_ptr->push_length;
566 }
567
568 if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
569 {
570 png_size_t save_size = png_ptr->save_buffer_size;
571 png_uint_32 idat_size = png_ptr->idat_size;
572
573 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
574 * are of different types and we don't know which variable has the fewest
575 * bits. Carefully select the smaller and cast it to the type of the
576 * larger - this cannot overflow. Do not cast in the following test - it
577 * will break on either 16-bit or 64-bit platforms.
578 */
579 if (idat_size < save_size)
580 save_size = (png_size_t)idat_size;
581
582 else
583 idat_size = (png_uint_32)save_size;
584
585 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
586
587 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
588
589 png_ptr->idat_size -= idat_size;
590 png_ptr->buffer_size -= save_size;
591 png_ptr->save_buffer_size -= save_size;
592 png_ptr->save_buffer_ptr += save_size;
593 }
594
595 if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
596 {
597 png_size_t save_size = png_ptr->current_buffer_size;
598 png_uint_32 idat_size = png_ptr->idat_size;
599
600 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
601 * are of different types and we don't know which variable has the fewest
602 * bits. Carefully select the smaller and cast it to the type of the
603 * larger - this cannot overflow.
604 */
605 if (idat_size < save_size)
606 save_size = (png_size_t)idat_size;
607
608 else
609 idat_size = (png_uint_32)save_size;
610
611 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
612
613 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
614
615 png_ptr->idat_size -= idat_size;
616 png_ptr->buffer_size -= save_size;
617 png_ptr->current_buffer_size -= save_size;
618 png_ptr->current_buffer_ptr += save_size;
619 }
620
621 if (png_ptr->idat_size == 0)
622 {
623 PNG_PUSH_SAVE_BUFFER_IF_LT(4)
624 png_crc_finish(png_ptr, 0);
625 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
626 png_ptr->mode |= PNG_AFTER_IDAT;
627 png_ptr->zowner = 0;
628 }
629}
630
631void /* PRIVATE */
632png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
633 png_size_t buffer_length)
634{
635 /* The caller checks for a non-zero buffer length. */
636 if (!(buffer_length > 0) || buffer == NULL)
637 png_error(png_ptr, "No IDAT data (internal error)");
638
639 /* This routine must process all the data it has been given
640 * before returning, calling the row callback as required to
641 * handle the uncompressed results.
642 */
643 png_ptr->zstream.next_in = buffer;
644 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
645 png_ptr->zstream.avail_in = (uInt)buffer_length;
646
647 /* Keep going until the decompressed data is all processed
648 * or the stream marked as finished.
649 */
650 while (png_ptr->zstream.avail_in > 0 &&
651 (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
652 {
653 int ret;
654
655 /* We have data for zlib, but we must check that zlib
656 * has someplace to put the results. It doesn't matter
657 * if we don't expect any results -- it may be the input
658 * data is just the LZ end code.
659 */
660 if (!(png_ptr->zstream.avail_out > 0))
661 {
662 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
663 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
664 png_ptr->iwidth) + 1);
665
666 png_ptr->zstream.next_out = png_ptr->row_buf;
667 }
668
669 /* Using Z_SYNC_FLUSH here means that an unterminated
670 * LZ stream (a stream with a missing end code) can still
671 * be handled, otherwise (Z_NO_FLUSH) a future zlib
672 * implementation might defer output and therefore
673 * change the current behavior (see comments in inflate.c
674 * for why this doesn't happen at present with zlib 1.2.5).
675 */
676 ret = PNG_INFLATE(png_ptr, Z_SYNC_FLUSH);
677
678 /* Check for any failure before proceeding. */
679 if (ret != Z_OK && ret != Z_STREAM_END)
680 {
681 /* Terminate the decompression. */
682 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
683 png_ptr->zowner = 0;
684
685 /* This may be a truncated stream (missing or
686 * damaged end code). Treat that as a warning.
687 */
688 if (png_ptr->row_number >= png_ptr->num_rows ||
689 png_ptr->pass > 6)
690 png_warning(png_ptr, "Truncated compressed data in IDAT");
691
692 else
693 png_error(png_ptr, "Decompression error in IDAT");
694
695 /* Skip the check on unprocessed input */
696 return;
697 }
698
699 /* Did inflate output any data? */
700 if (png_ptr->zstream.next_out != png_ptr->row_buf)
701 {
702 /* Is this unexpected data after the last row?
703 * If it is, artificially terminate the LZ output
704 * here.
705 */
706 if (png_ptr->row_number >= png_ptr->num_rows ||
707 png_ptr->pass > 6)
708 {
709 /* Extra data. */
710 png_warning(png_ptr, "Extra compressed data in IDAT");
711 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
712 png_ptr->zowner = 0;
713
714 /* Do no more processing; skip the unprocessed
715 * input check below.
716 */
717 return;
718 }
719
720 /* Do we have a complete row? */
721 if (png_ptr->zstream.avail_out == 0)
722 png_push_process_row(png_ptr);
723 }
724
725 /* And check for the end of the stream. */
726 if (ret == Z_STREAM_END)
727 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
728 }
729
730 /* All the data should have been processed, if anything
731 * is left at this point we have bytes of IDAT data
732 * after the zlib end code.
733 */
734 if (png_ptr->zstream.avail_in > 0)
735 png_warning(png_ptr, "Extra compression data in IDAT");
736}
737
738void /* PRIVATE */
739png_push_process_row(png_structrp png_ptr)
740{
741 /* 1.5.6: row_info moved out of png_struct to a local here. */
742 png_row_info row_info;
743
744 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
745 row_info.color_type = png_ptr->color_type;
746 row_info.bit_depth = png_ptr->bit_depth;
747 row_info.channels = png_ptr->channels;
748 row_info.pixel_depth = png_ptr->pixel_depth;
749 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
750
751 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
752 {
753 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
754 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
755 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
756 else
757 png_error(png_ptr, "bad adaptive filter value");
758 }
759
760 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
761 * 1.5.6, while the buffer really is this big in current versions of libpng
762 * it may not be in the future, so this was changed just to copy the
763 * interlaced row count:
764 */
765 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
766
767#ifdef PNG_READ_TRANSFORMS_SUPPORTED
768 if (png_ptr->transformations != 0)
769 png_do_read_transformations(png_ptr, &row_info);
770#endif
771
772 /* The transformed pixel depth should match the depth now in row_info. */
773 if (png_ptr->transformed_pixel_depth == 0)
774 {
775 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
776 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
777 png_error(png_ptr, "progressive row overflow");
778 }
779
780 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
781 png_error(png_ptr, "internal progressive row size calculation error");
782
783
784#ifdef PNG_READ_INTERLACING_SUPPORTED
785 /* Expand interlaced rows to full size */
786 if (png_ptr->interlaced != 0 &&
787 (png_ptr->transformations & PNG_INTERLACE) != 0)
788 {
789 if (png_ptr->pass < 6)
790 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
791 png_ptr->transformations);
792
793 switch (png_ptr->pass)
794 {
795 case 0:
796 {
797 int i;
798 for (i = 0; i < 8 && png_ptr->pass == 0; i++)
799 {
800 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
801 png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
802 }
803
804 if (png_ptr->pass == 2) /* Pass 1 might be empty */
805 {
806 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
807 {
808 png_push_have_row(png_ptr, NULL);
809 png_read_push_finish_row(png_ptr);
810 }
811 }
812
813 if (png_ptr->pass == 4 && png_ptr->height <= 4)
814 {
815 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
816 {
817 png_push_have_row(png_ptr, NULL);
818 png_read_push_finish_row(png_ptr);
819 }
820 }
821
822 if (png_ptr->pass == 6 && png_ptr->height <= 4)
823 {
824 png_push_have_row(png_ptr, NULL);
825 png_read_push_finish_row(png_ptr);
826 }
827
828 break;
829 }
830
831 case 1:
832 {
833 int i;
834 for (i = 0; i < 8 && png_ptr->pass == 1; i++)
835 {
836 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
837 png_read_push_finish_row(png_ptr);
838 }
839
840 if (png_ptr->pass == 2) /* Skip top 4 generated rows */
841 {
842 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
843 {
844 png_push_have_row(png_ptr, NULL);
845 png_read_push_finish_row(png_ptr);
846 }
847 }
848
849 break;
850 }
851
852 case 2:
853 {
854 int i;
855
856 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
857 {
858 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
859 png_read_push_finish_row(png_ptr);
860 }
861
862 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
863 {
864 png_push_have_row(png_ptr, NULL);
865 png_read_push_finish_row(png_ptr);
866 }
867
868 if (png_ptr->pass == 4) /* Pass 3 might be empty */
869 {
870 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
871 {
872 png_push_have_row(png_ptr, NULL);
873 png_read_push_finish_row(png_ptr);
874 }
875 }
876
877 break;
878 }
879
880 case 3:
881 {
882 int i;
883
884 for (i = 0; i < 4 && png_ptr->pass == 3; i++)
885 {
886 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
887 png_read_push_finish_row(png_ptr);
888 }
889
890 if (png_ptr->pass == 4) /* Skip top two generated rows */
891 {
892 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
893 {
894 png_push_have_row(png_ptr, NULL);
895 png_read_push_finish_row(png_ptr);
896 }
897 }
898
899 break;
900 }
901
902 case 4:
903 {
904 int i;
905
906 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
907 {
908 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
909 png_read_push_finish_row(png_ptr);
910 }
911
912 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
913 {
914 png_push_have_row(png_ptr, NULL);
915 png_read_push_finish_row(png_ptr);
916 }
917
918 if (png_ptr->pass == 6) /* Pass 5 might be empty */
919 {
920 png_push_have_row(png_ptr, NULL);
921 png_read_push_finish_row(png_ptr);
922 }
923
924 break;
925 }
926
927 case 5:
928 {
929 int i;
930
931 for (i = 0; i < 2 && png_ptr->pass == 5; i++)
932 {
933 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
934 png_read_push_finish_row(png_ptr);
935 }
936
937 if (png_ptr->pass == 6) /* Skip top generated row */
938 {
939 png_push_have_row(png_ptr, NULL);
940 png_read_push_finish_row(png_ptr);
941 }
942
943 break;
944 }
945
946 default:
947 case 6:
948 {
949 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
950 png_read_push_finish_row(png_ptr);
951
952 if (png_ptr->pass != 6)
953 break;
954
955 png_push_have_row(png_ptr, NULL);
956 png_read_push_finish_row(png_ptr);
957 }
958 }
959 }
960 else
961#endif
962 {
963 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
964 png_read_push_finish_row(png_ptr);
965 }
966}
967
968void /* PRIVATE */
969png_read_push_finish_row(png_structrp png_ptr)
970{
971#ifdef PNG_READ_INTERLACING_SUPPORTED
972 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
973
974 /* Start of interlace block */
975 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
976
977 /* Offset to next interlace block */
978 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
979
980 /* Start of interlace block in the y direction */
981 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
982
983 /* Offset to next interlace block in the y direction */
984 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
985
986 /* Height of interlace block. This is not currently used - if you need
987 * it, uncomment it here and in png.h
988 static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
989 */
990#endif
991
992 png_ptr->row_number++;
993 if (png_ptr->row_number < png_ptr->num_rows)
994 return;
995
996#ifdef PNG_READ_INTERLACING_SUPPORTED
997 if (png_ptr->interlaced != 0)
998 {
999 png_ptr->row_number = 0;
1000 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
1001
1002 do
1003 {
1004 png_ptr->pass++;
1005 if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1006 (png_ptr->pass == 3 && png_ptr->width < 3) ||
1007 (png_ptr->pass == 5 && png_ptr->width < 2))
1008 png_ptr->pass++;
1009
1010 if (png_ptr->pass > 7)
1011 png_ptr->pass--;
1012
1013 if (png_ptr->pass >= 7)
1014 break;
1015
1016 png_ptr->iwidth = (png_ptr->width +
1017 png_pass_inc[png_ptr->pass] - 1 -
1018 png_pass_start[png_ptr->pass]) /
1019 png_pass_inc[png_ptr->pass];
1020
1021 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
1022 break;
1023
1024 png_ptr->num_rows = (png_ptr->height +
1025 png_pass_yinc[png_ptr->pass] - 1 -
1026 png_pass_ystart[png_ptr->pass]) /
1027 png_pass_yinc[png_ptr->pass];
1028
1029 } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1030 }
1031#endif /* READ_INTERLACING */
1032}
1033
1034void /* PRIVATE */
1035png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1036{
1037 if (png_ptr->info_fn != NULL)
1038 (*(png_ptr->info_fn))(png_ptr, info_ptr);
1039}
1040
1041void /* PRIVATE */
1042png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1043{
1044 if (png_ptr->end_fn != NULL)
1045 (*(png_ptr->end_fn))(png_ptr, info_ptr);
1046}
1047
1048void /* PRIVATE */
1049png_push_have_row(png_structrp png_ptr, png_bytep row)
1050{
1051 if (png_ptr->row_fn != NULL)
1052 (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1053 (int)png_ptr->pass);
1054}
1055
1056#ifdef PNG_READ_INTERLACING_SUPPORTED
1057void PNGAPI
1058png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1059 png_const_bytep new_row)
1060{
1061 if (png_ptr == NULL)
1062 return;
1063
1064 /* new_row is a flag here - if it is NULL then the app callback was called
1065 * from an empty row (see the calls to png_struct::row_fn below), otherwise
1066 * it must be png_ptr->row_buf+1
1067 */
1068 if (new_row != NULL)
1069 png_combine_row(png_ptr, old_row, 1/*blocky display*/);
1070}
1071#endif /* READ_INTERLACING */
1072
1073void PNGAPI
1074png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1075 png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1076 png_progressive_end_ptr end_fn)
1077{
1078 if (png_ptr == NULL)
1079 return;
1080
1081 png_ptr->info_fn = info_fn;
1082 png_ptr->row_fn = row_fn;
1083 png_ptr->end_fn = end_fn;
1084
1085 png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1086}
1087
1088png_voidp PNGAPI
1089png_get_progressive_ptr(png_const_structrp png_ptr)
1090{
1091 if (png_ptr == NULL)
1092 return (NULL);
1093
1094 return png_ptr->io_ptr;
1095}
1096#endif /* PROGRESSIVE_READ */
1097