1 /* pngpread.c - read a png file in push mode
2 *
3 * Last changed in libpng 1.6.0 [February 14, 2013]
4 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
7 *
8 * This code is released under the libpng license.
9 * For conditions of distribution and use, see the disclaimer
10 * and license in png.h
11 */
12
13 #include "pngpriv.h"
14
15 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
16
17 /* Push model modes */
18 #define PNG_READ_SIG_MODE 0
19 #define PNG_READ_CHUNK_MODE 1
20 #define PNG_READ_IDAT_MODE 2
21 #define PNG_SKIP_MODE 3
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 void PNGAPI
png_process_data(png_structrp png_ptr,png_inforp info_ptr,png_bytep buffer,png_size_t buffer_size)29 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
30 png_bytep buffer, png_size_t buffer_size)
31 {
32 if (png_ptr == NULL || info_ptr == NULL)
33 return;
34
35 png_push_restore_buffer(png_ptr, buffer, buffer_size);
36
37 while (png_ptr->buffer_size)
38 {
39 png_process_some_data(png_ptr, info_ptr);
40 }
41 }
42
43 png_size_t PNGAPI
png_process_data_pause(png_structrp png_ptr,int save)44 png_process_data_pause(png_structrp png_ptr, int save)
45 {
46 if (png_ptr != NULL)
47 {
48 /* It's easiest for the caller if we do the save, then the caller doesn't
49 * have to supply the same data again:
50 */
51 if (save)
52 png_push_save_buffer(png_ptr);
53 else
54 {
55 /* This includes any pending saved bytes: */
56 png_size_t remaining = png_ptr->buffer_size;
57 png_ptr->buffer_size = 0;
58
59 /* So subtract the saved buffer size, unless all the data
60 * is actually 'saved', in which case we just return 0
61 */
62 if (png_ptr->save_buffer_size < remaining)
63 return remaining - png_ptr->save_buffer_size;
64 }
65 }
66
67 return 0;
68 }
69
70 png_uint_32 PNGAPI
png_process_data_skip(png_structrp png_ptr)71 png_process_data_skip(png_structrp png_ptr)
72 {
73 png_uint_32 remaining = 0;
74
75 if (png_ptr != NULL && png_ptr->process_mode == PNG_SKIP_MODE &&
76 png_ptr->skip_length > 0)
77 {
78 /* At the end of png_process_data the buffer size must be 0 (see the loop
79 * above) so we can detect a broken call here:
80 */
81 if (png_ptr->buffer_size != 0)
82 png_error(png_ptr,
83 "png_process_data_skip called inside png_process_data");
84
85 /* If is impossible for there to be a saved buffer at this point -
86 * otherwise we could not be in SKIP mode. This will also happen if
87 * png_process_skip is called inside png_process_data (but only very
88 * rarely.)
89 */
90 if (png_ptr->save_buffer_size != 0)
91 png_error(png_ptr, "png_process_data_skip called with saved data");
92
93 remaining = png_ptr->skip_length;
94 png_ptr->skip_length = 0;
95 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
96 }
97
98 return remaining;
99 }
100
101 /* What we do with the incoming data depends on what we were previously
102 * doing before we ran out of data...
103 */
104 void /* PRIVATE */
png_process_some_data(png_structrp png_ptr,png_inforp info_ptr)105 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
106 {
107 if (png_ptr == NULL)
108 return;
109
110 switch (png_ptr->process_mode)
111 {
112 case PNG_READ_SIG_MODE:
113 {
114 png_push_read_sig(png_ptr, info_ptr);
115 break;
116 }
117
118 case PNG_READ_CHUNK_MODE:
119 {
120 png_push_read_chunk(png_ptr, info_ptr);
121 break;
122 }
123
124 case PNG_READ_IDAT_MODE:
125 {
126 png_push_read_IDAT(png_ptr);
127 break;
128 }
129
130 case PNG_SKIP_MODE:
131 {
132 png_push_crc_finish(png_ptr);
133 break;
134 }
135
136 default:
137 {
138 png_ptr->buffer_size = 0;
139 break;
140 }
141 }
142 }
143
144 /* Read any remaining signature bytes from the stream and compare them with
145 * the correct PNG signature. It is possible that this routine is called
146 * with bytes already read from the signature, either because they have been
147 * checked by the calling application, or because of multiple calls to this
148 * routine.
149 */
150 void /* PRIVATE */
png_push_read_sig(png_structrp png_ptr,png_inforp info_ptr)151 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
152 {
153 png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
154 num_to_check = 8 - num_checked;
155
156 if (png_ptr->buffer_size < num_to_check)
157 {
158 num_to_check = png_ptr->buffer_size;
159 }
160
161 png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
162 num_to_check);
163 png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
164
165 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
166 {
167 if (num_checked < 4 &&
168 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
169 png_error(png_ptr, "Not a PNG file");
170
171 else
172 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
173 }
174 else
175 {
176 if (png_ptr->sig_bytes >= 8)
177 {
178 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
179 }
180 }
181 }
182
183 void /* PRIVATE */
png_push_read_chunk(png_structrp png_ptr,png_inforp info_ptr)184 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
185 {
186 png_uint_32 chunk_name;
187 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
188 int keep; /* unknown handling method */
189 #endif
190
191 /* First we make sure we have enough data for the 4 byte chunk name
192 * and the 4 byte chunk length before proceeding with decoding the
193 * chunk data. To fully decode each of these chunks, we also make
194 * sure we have enough data in the buffer for the 4 byte CRC at the
195 * end of every chunk (except IDAT, which is handled separately).
196 */
197 if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
198 {
199 png_byte chunk_length[4];
200 png_byte chunk_tag[4];
201
202 if (png_ptr->buffer_size < 8)
203 {
204 png_push_save_buffer(png_ptr);
205 return;
206 }
207
208 png_push_fill_buffer(png_ptr, chunk_length, 4);
209 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
210 png_reset_crc(png_ptr);
211 png_crc_read(png_ptr, chunk_tag, 4);
212 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
213 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
214 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
215 }
216
217 chunk_name = png_ptr->chunk_name;
218
219 if (chunk_name == png_IDAT)
220 {
221 if (png_ptr->mode & PNG_AFTER_IDAT)
222 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
223
224 /* If we reach an IDAT chunk, this means we have read all of the
225 * header chunks, and we can start reading the image (or if this
226 * is called after the image has been read - we have an error).
227 */
228 if (!(png_ptr->mode & PNG_HAVE_IHDR))
229 png_error(png_ptr, "Missing IHDR before IDAT");
230
231 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
232 !(png_ptr->mode & PNG_HAVE_PLTE))
233 png_error(png_ptr, "Missing PLTE before IDAT");
234
235 png_ptr->mode |= PNG_HAVE_IDAT;
236
237 if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
238 if (png_ptr->push_length == 0)
239 return;
240
241 if (png_ptr->mode & PNG_AFTER_IDAT)
242 png_benign_error(png_ptr, "Too many IDATs found");
243 }
244
245 if (chunk_name == png_IHDR)
246 {
247 if (png_ptr->push_length != 13)
248 png_error(png_ptr, "Invalid IHDR length");
249
250 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
251 {
252 png_push_save_buffer(png_ptr);
253 return;
254 }
255
256 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
257 }
258
259 else if (chunk_name == png_IEND)
260 {
261 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
262 {
263 png_push_save_buffer(png_ptr);
264 return;
265 }
266
267 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
268
269 png_ptr->process_mode = PNG_READ_DONE_MODE;
270 png_push_have_end(png_ptr, info_ptr);
271 }
272
273 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
274 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
275 {
276 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
277 {
278 png_push_save_buffer(png_ptr);
279 return;
280 }
281
282 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
283
284 if (chunk_name == png_PLTE)
285 png_ptr->mode |= PNG_HAVE_PLTE;
286 }
287
288 #endif
289 else if (chunk_name == png_PLTE)
290 {
291 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
292 {
293 png_push_save_buffer(png_ptr);
294 return;
295 }
296 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
297 }
298
299 else if (chunk_name == png_IDAT)
300 {
301 png_ptr->idat_size = png_ptr->push_length;
302 png_ptr->process_mode = PNG_READ_IDAT_MODE;
303 png_push_have_info(png_ptr, info_ptr);
304 png_ptr->zstream.avail_out =
305 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
306 png_ptr->iwidth) + 1;
307 png_ptr->zstream.next_out = png_ptr->row_buf;
308 return;
309 }
310
311 #ifdef PNG_READ_gAMA_SUPPORTED
312 else if (png_ptr->chunk_name == png_gAMA)
313 {
314 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
315 {
316 png_push_save_buffer(png_ptr);
317 return;
318 }
319
320 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
321 }
322
323 #endif
324 #ifdef PNG_READ_sBIT_SUPPORTED
325 else if (png_ptr->chunk_name == png_sBIT)
326 {
327 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
328 {
329 png_push_save_buffer(png_ptr);
330 return;
331 }
332
333 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
334 }
335
336 #endif
337 #ifdef PNG_READ_cHRM_SUPPORTED
338 else if (png_ptr->chunk_name == png_cHRM)
339 {
340 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
341 {
342 png_push_save_buffer(png_ptr);
343 return;
344 }
345
346 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
347 }
348
349 #endif
350 #ifdef PNG_READ_sRGB_SUPPORTED
351 else if (chunk_name == png_sRGB)
352 {
353 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
354 {
355 png_push_save_buffer(png_ptr);
356 return;
357 }
358
359 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
360 }
361
362 #endif
363 #ifdef PNG_READ_iCCP_SUPPORTED
364 else if (png_ptr->chunk_name == png_iCCP)
365 {
366 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
367 {
368 png_push_save_buffer(png_ptr);
369 return;
370 }
371
372 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
373 }
374
375 #endif
376 #ifdef PNG_READ_sPLT_SUPPORTED
377 else if (chunk_name == png_sPLT)
378 {
379 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
380 {
381 png_push_save_buffer(png_ptr);
382 return;
383 }
384
385 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
386 }
387
388 #endif
389 #ifdef PNG_READ_tRNS_SUPPORTED
390 else if (chunk_name == png_tRNS)
391 {
392 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
393 {
394 png_push_save_buffer(png_ptr);
395 return;
396 }
397
398 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
399 }
400
401 #endif
402 #ifdef PNG_READ_bKGD_SUPPORTED
403 else if (chunk_name == png_bKGD)
404 {
405 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
406 {
407 png_push_save_buffer(png_ptr);
408 return;
409 }
410
411 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
412 }
413
414 #endif
415 #ifdef PNG_READ_hIST_SUPPORTED
416 else if (chunk_name == png_hIST)
417 {
418 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
419 {
420 png_push_save_buffer(png_ptr);
421 return;
422 }
423
424 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
425 }
426
427 #endif
428 #ifdef PNG_READ_pHYs_SUPPORTED
429 else if (chunk_name == png_pHYs)
430 {
431 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
432 {
433 png_push_save_buffer(png_ptr);
434 return;
435 }
436
437 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
438 }
439
440 #endif
441 #ifdef PNG_READ_oFFs_SUPPORTED
442 else if (chunk_name == png_oFFs)
443 {
444 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
445 {
446 png_push_save_buffer(png_ptr);
447 return;
448 }
449
450 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
451 }
452 #endif
453
454 #ifdef PNG_READ_pCAL_SUPPORTED
455 else if (chunk_name == png_pCAL)
456 {
457 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
458 {
459 png_push_save_buffer(png_ptr);
460 return;
461 }
462
463 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
464 }
465
466 #endif
467 #ifdef PNG_READ_sCAL_SUPPORTED
468 else if (chunk_name == png_sCAL)
469 {
470 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
471 {
472 png_push_save_buffer(png_ptr);
473 return;
474 }
475
476 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
477 }
478
479 #endif
480 #ifdef PNG_READ_tIME_SUPPORTED
481 else if (chunk_name == png_tIME)
482 {
483 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
484 {
485 png_push_save_buffer(png_ptr);
486 return;
487 }
488
489 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
490 }
491
492 #endif
493 #ifdef PNG_READ_tEXt_SUPPORTED
494 else if (chunk_name == png_tEXt)
495 {
496 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
497 {
498 png_push_save_buffer(png_ptr);
499 return;
500 }
501
502 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
503 }
504
505 #endif
506 #ifdef PNG_READ_zTXt_SUPPORTED
507 else if (chunk_name == png_zTXt)
508 {
509 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
510 {
511 png_push_save_buffer(png_ptr);
512 return;
513 }
514
515 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
516 }
517
518 #endif
519 #ifdef PNG_READ_iTXt_SUPPORTED
520 else if (chunk_name == png_iTXt)
521 {
522 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
523 {
524 png_push_save_buffer(png_ptr);
525 return;
526 }
527
528 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
529 }
530
531 #endif
532 else
533 {
534 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
535 {
536 png_push_save_buffer(png_ptr);
537 return;
538 }
539 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
540 PNG_HANDLE_CHUNK_AS_DEFAULT);
541 }
542
543 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
544 }
545
546 void /* PRIVATE */
png_push_crc_skip(png_structrp png_ptr,png_uint_32 skip)547 png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
548 {
549 png_ptr->process_mode = PNG_SKIP_MODE;
550 png_ptr->skip_length = skip;
551 }
552
553 void /* PRIVATE */
png_push_crc_finish(png_structrp png_ptr)554 png_push_crc_finish(png_structrp png_ptr)
555 {
556 if (png_ptr->skip_length && png_ptr->save_buffer_size)
557 {
558 png_size_t save_size = png_ptr->save_buffer_size;
559 png_uint_32 skip_length = png_ptr->skip_length;
560
561 /* We want the smaller of 'skip_length' and 'save_buffer_size', but
562 * they are of different types and we don't know which variable has the
563 * fewest bits. Carefully select the smaller and cast it to the type of
564 * the larger - this cannot overflow. Do not cast in the following test
565 * - it will break on either 16 or 64 bit platforms.
566 */
567 if (skip_length < save_size)
568 save_size = (png_size_t)skip_length;
569
570 else
571 skip_length = (png_uint_32)save_size;
572
573 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
574
575 png_ptr->skip_length -= skip_length;
576 png_ptr->buffer_size -= save_size;
577 png_ptr->save_buffer_size -= save_size;
578 png_ptr->save_buffer_ptr += save_size;
579 }
580 if (png_ptr->skip_length && png_ptr->current_buffer_size)
581 {
582 png_size_t save_size = png_ptr->current_buffer_size;
583 png_uint_32 skip_length = png_ptr->skip_length;
584
585 /* We want the smaller of 'skip_length' and 'current_buffer_size', here,
586 * the same problem exists as above and the same solution.
587 */
588 if (skip_length < save_size)
589 save_size = (png_size_t)skip_length;
590
591 else
592 skip_length = (png_uint_32)save_size;
593
594 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
595
596 png_ptr->skip_length -= skip_length;
597 png_ptr->buffer_size -= save_size;
598 png_ptr->current_buffer_size -= save_size;
599 png_ptr->current_buffer_ptr += save_size;
600 }
601 if (!png_ptr->skip_length)
602 {
603 if (png_ptr->buffer_size < 4)
604 {
605 png_push_save_buffer(png_ptr);
606 return;
607 }
608
609 png_crc_finish(png_ptr, 0);
610 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
611 }
612 }
613
614 void PNGCBAPI
png_push_fill_buffer(png_structp png_ptr,png_bytep buffer,png_size_t length)615 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
616 {
617 png_bytep ptr;
618
619 if (png_ptr == NULL)
620 return;
621
622 ptr = buffer;
623 if (png_ptr->save_buffer_size)
624 {
625 png_size_t save_size;
626
627 if (length < png_ptr->save_buffer_size)
628 save_size = length;
629
630 else
631 save_size = png_ptr->save_buffer_size;
632
633 memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
634 length -= save_size;
635 ptr += save_size;
636 png_ptr->buffer_size -= save_size;
637 png_ptr->save_buffer_size -= save_size;
638 png_ptr->save_buffer_ptr += save_size;
639 }
640 if (length && png_ptr->current_buffer_size)
641 {
642 png_size_t save_size;
643
644 if (length < png_ptr->current_buffer_size)
645 save_size = length;
646
647 else
648 save_size = png_ptr->current_buffer_size;
649
650 memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
651 png_ptr->buffer_size -= save_size;
652 png_ptr->current_buffer_size -= save_size;
653 png_ptr->current_buffer_ptr += save_size;
654 }
655 }
656
657 void /* PRIVATE */
png_push_save_buffer(png_structrp png_ptr)658 png_push_save_buffer(png_structrp png_ptr)
659 {
660 if (png_ptr->save_buffer_size)
661 {
662 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
663 {
664 png_size_t i, istop;
665 png_bytep sp;
666 png_bytep dp;
667
668 istop = png_ptr->save_buffer_size;
669 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
670 i < istop; i++, sp++, dp++)
671 {
672 *dp = *sp;
673 }
674 }
675 }
676 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
677 png_ptr->save_buffer_max)
678 {
679 png_size_t new_max;
680 png_bytep old_buffer;
681
682 if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
683 (png_ptr->current_buffer_size + 256))
684 {
685 png_error(png_ptr, "Potential overflow of save_buffer");
686 }
687
688 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
689 old_buffer = png_ptr->save_buffer;
690 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
691 (png_size_t)new_max);
692
693 if (png_ptr->save_buffer == NULL)
694 {
695 png_free(png_ptr, old_buffer);
696 png_error(png_ptr, "Insufficient memory for save_buffer");
697 }
698
699 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
700 png_free(png_ptr, old_buffer);
701 png_ptr->save_buffer_max = new_max;
702 }
703 if (png_ptr->current_buffer_size)
704 {
705 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
706 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
707 png_ptr->save_buffer_size += png_ptr->current_buffer_size;
708 png_ptr->current_buffer_size = 0;
709 }
710 png_ptr->save_buffer_ptr = png_ptr->save_buffer;
711 png_ptr->buffer_size = 0;
712 }
713
714 void /* PRIVATE */
png_push_restore_buffer(png_structrp png_ptr,png_bytep buffer,png_size_t buffer_length)715 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
716 png_size_t buffer_length)
717 {
718 png_ptr->current_buffer = buffer;
719 png_ptr->current_buffer_size = buffer_length;
720 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
721 png_ptr->current_buffer_ptr = png_ptr->current_buffer;
722 }
723
724 void /* PRIVATE */
png_push_read_IDAT(png_structrp png_ptr)725 png_push_read_IDAT(png_structrp png_ptr)
726 {
727 if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
728 {
729 png_byte chunk_length[4];
730 png_byte chunk_tag[4];
731
732 /* TODO: this code can be commoned up with the same code in push_read */
733 if (png_ptr->buffer_size < 8)
734 {
735 png_push_save_buffer(png_ptr);
736 return;
737 }
738
739 png_push_fill_buffer(png_ptr, chunk_length, 4);
740 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
741 png_reset_crc(png_ptr);
742 png_crc_read(png_ptr, chunk_tag, 4);
743 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
744 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
745
746 if (png_ptr->chunk_name != png_IDAT)
747 {
748 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
749
750 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
751 png_error(png_ptr, "Not enough compressed data");
752
753 return;
754 }
755
756 png_ptr->idat_size = png_ptr->push_length;
757 }
758
759 if (png_ptr->idat_size && png_ptr->save_buffer_size)
760 {
761 png_size_t save_size = png_ptr->save_buffer_size;
762 png_uint_32 idat_size = png_ptr->idat_size;
763
764 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
765 * are of different types and we don't know which variable has the fewest
766 * bits. Carefully select the smaller and cast it to the type of the
767 * larger - this cannot overflow. Do not cast in the following test - it
768 * will break on either 16 or 64 bit platforms.
769 */
770 if (idat_size < save_size)
771 save_size = (png_size_t)idat_size;
772
773 else
774 idat_size = (png_uint_32)save_size;
775
776 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
777
778 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
779
780 png_ptr->idat_size -= idat_size;
781 png_ptr->buffer_size -= save_size;
782 png_ptr->save_buffer_size -= save_size;
783 png_ptr->save_buffer_ptr += save_size;
784 }
785
786 if (png_ptr->idat_size && png_ptr->current_buffer_size)
787 {
788 png_size_t save_size = png_ptr->current_buffer_size;
789 png_uint_32 idat_size = png_ptr->idat_size;
790
791 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
792 * are of different types and we don't know which variable has the fewest
793 * bits. Carefully select the smaller and cast it to the type of the
794 * larger - this cannot overflow.
795 */
796 if (idat_size < save_size)
797 save_size = (png_size_t)idat_size;
798
799 else
800 idat_size = (png_uint_32)save_size;
801
802 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
803
804 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
805
806 png_ptr->idat_size -= idat_size;
807 png_ptr->buffer_size -= save_size;
808 png_ptr->current_buffer_size -= save_size;
809 png_ptr->current_buffer_ptr += save_size;
810 }
811 if (!png_ptr->idat_size)
812 {
813 if (png_ptr->buffer_size < 4)
814 {
815 png_push_save_buffer(png_ptr);
816 return;
817 }
818
819 png_crc_finish(png_ptr, 0);
820 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
821 png_ptr->mode |= PNG_AFTER_IDAT;
822 png_ptr->zowner = 0;
823 }
824 }
825
826 void /* PRIVATE */
png_process_IDAT_data(png_structrp png_ptr,png_bytep buffer,png_size_t buffer_length)827 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
828 png_size_t buffer_length)
829 {
830 /* The caller checks for a non-zero buffer length. */
831 if (!(buffer_length > 0) || buffer == NULL)
832 png_error(png_ptr, "No IDAT data (internal error)");
833
834 /* This routine must process all the data it has been given
835 * before returning, calling the row callback as required to
836 * handle the uncompressed results.
837 */
838 png_ptr->zstream.next_in = buffer;
839 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
840 png_ptr->zstream.avail_in = (uInt)buffer_length;
841
842 /* Keep going until the decompressed data is all processed
843 * or the stream marked as finished.
844 */
845 while (png_ptr->zstream.avail_in > 0 &&
846 !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
847 {
848 int ret;
849
850 /* We have data for zlib, but we must check that zlib
851 * has someplace to put the results. It doesn't matter
852 * if we don't expect any results -- it may be the input
853 * data is just the LZ end code.
854 */
855 if (!(png_ptr->zstream.avail_out > 0))
856 {
857 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
858 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
859 png_ptr->iwidth) + 1);
860
861 png_ptr->zstream.next_out = png_ptr->row_buf;
862 }
863
864 /* Using Z_SYNC_FLUSH here means that an unterminated
865 * LZ stream (a stream with a missing end code) can still
866 * be handled, otherwise (Z_NO_FLUSH) a future zlib
867 * implementation might defer output and therefore
868 * change the current behavior (see comments in inflate.c
869 * for why this doesn't happen at present with zlib 1.2.5).
870 */
871 ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
872
873 /* Check for any failure before proceeding. */
874 if (ret != Z_OK && ret != Z_STREAM_END)
875 {
876 /* Terminate the decompression. */
877 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
878 png_ptr->zowner = 0;
879
880 /* This may be a truncated stream (missing or
881 * damaged end code). Treat that as a warning.
882 */
883 if (png_ptr->row_number >= png_ptr->num_rows ||
884 png_ptr->pass > 6)
885 png_warning(png_ptr, "Truncated compressed data in IDAT");
886
887 else
888 png_error(png_ptr, "Decompression error in IDAT");
889
890 /* Skip the check on unprocessed input */
891 return;
892 }
893
894 /* Did inflate output any data? */
895 if (png_ptr->zstream.next_out != png_ptr->row_buf)
896 {
897 /* Is this unexpected data after the last row?
898 * If it is, artificially terminate the LZ output
899 * here.
900 */
901 if (png_ptr->row_number >= png_ptr->num_rows ||
902 png_ptr->pass > 6)
903 {
904 /* Extra data. */
905 png_warning(png_ptr, "Extra compressed data in IDAT");
906 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
907 png_ptr->zowner = 0;
908
909 /* Do no more processing; skip the unprocessed
910 * input check below.
911 */
912 return;
913 }
914
915 /* Do we have a complete row? */
916 if (png_ptr->zstream.avail_out == 0)
917 png_push_process_row(png_ptr);
918 }
919
920 /* And check for the end of the stream. */
921 if (ret == Z_STREAM_END)
922 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
923 }
924
925 /* All the data should have been processed, if anything
926 * is left at this point we have bytes of IDAT data
927 * after the zlib end code.
928 */
929 if (png_ptr->zstream.avail_in > 0)
930 png_warning(png_ptr, "Extra compression data in IDAT");
931 }
932
933 void /* PRIVATE */
png_push_process_row(png_structrp png_ptr)934 png_push_process_row(png_structrp png_ptr)
935 {
936 /* 1.5.6: row_info moved out of png_struct to a local here. */
937 png_row_info row_info;
938
939 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
940 row_info.color_type = png_ptr->color_type;
941 row_info.bit_depth = png_ptr->bit_depth;
942 row_info.channels = png_ptr->channels;
943 row_info.pixel_depth = png_ptr->pixel_depth;
944 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
945
946 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
947 {
948 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
949 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
950 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
951 else
952 png_error(png_ptr, "bad adaptive filter value");
953 }
954
955 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
956 * 1.5.6, while the buffer really is this big in current versions of libpng
957 * it may not be in the future, so this was changed just to copy the
958 * interlaced row count:
959 */
960 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
961
962 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
963 if (png_ptr->transformations)
964 png_do_read_transformations(png_ptr, &row_info);
965 #endif
966
967 /* The transformed pixel depth should match the depth now in row_info. */
968 if (png_ptr->transformed_pixel_depth == 0)
969 {
970 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
971 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
972 png_error(png_ptr, "progressive row overflow");
973 }
974
975 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
976 png_error(png_ptr, "internal progressive row size calculation error");
977
978
979 #ifdef PNG_READ_INTERLACING_SUPPORTED
980 /* Blow up interlaced rows to full size */
981 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
982 {
983 if (png_ptr->pass < 6)
984 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
985 png_ptr->transformations);
986
987 switch (png_ptr->pass)
988 {
989 case 0:
990 {
991 int i;
992 for (i = 0; i < 8 && png_ptr->pass == 0; i++)
993 {
994 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
995 png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
996 }
997
998 if (png_ptr->pass == 2) /* Pass 1 might be empty */
999 {
1000 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1001 {
1002 png_push_have_row(png_ptr, NULL);
1003 png_read_push_finish_row(png_ptr);
1004 }
1005 }
1006
1007 if (png_ptr->pass == 4 && png_ptr->height <= 4)
1008 {
1009 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1010 {
1011 png_push_have_row(png_ptr, NULL);
1012 png_read_push_finish_row(png_ptr);
1013 }
1014 }
1015
1016 if (png_ptr->pass == 6 && png_ptr->height <= 4)
1017 {
1018 png_push_have_row(png_ptr, NULL);
1019 png_read_push_finish_row(png_ptr);
1020 }
1021
1022 break;
1023 }
1024
1025 case 1:
1026 {
1027 int i;
1028 for (i = 0; i < 8 && png_ptr->pass == 1; i++)
1029 {
1030 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1031 png_read_push_finish_row(png_ptr);
1032 }
1033
1034 if (png_ptr->pass == 2) /* Skip top 4 generated rows */
1035 {
1036 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1037 {
1038 png_push_have_row(png_ptr, NULL);
1039 png_read_push_finish_row(png_ptr);
1040 }
1041 }
1042
1043 break;
1044 }
1045
1046 case 2:
1047 {
1048 int i;
1049
1050 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1051 {
1052 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1053 png_read_push_finish_row(png_ptr);
1054 }
1055
1056 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1057 {
1058 png_push_have_row(png_ptr, NULL);
1059 png_read_push_finish_row(png_ptr);
1060 }
1061
1062 if (png_ptr->pass == 4) /* Pass 3 might be empty */
1063 {
1064 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1065 {
1066 png_push_have_row(png_ptr, NULL);
1067 png_read_push_finish_row(png_ptr);
1068 }
1069 }
1070
1071 break;
1072 }
1073
1074 case 3:
1075 {
1076 int i;
1077
1078 for (i = 0; i < 4 && png_ptr->pass == 3; i++)
1079 {
1080 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1081 png_read_push_finish_row(png_ptr);
1082 }
1083
1084 if (png_ptr->pass == 4) /* Skip top two generated rows */
1085 {
1086 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1087 {
1088 png_push_have_row(png_ptr, NULL);
1089 png_read_push_finish_row(png_ptr);
1090 }
1091 }
1092
1093 break;
1094 }
1095
1096 case 4:
1097 {
1098 int i;
1099
1100 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1101 {
1102 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1103 png_read_push_finish_row(png_ptr);
1104 }
1105
1106 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1107 {
1108 png_push_have_row(png_ptr, NULL);
1109 png_read_push_finish_row(png_ptr);
1110 }
1111
1112 if (png_ptr->pass == 6) /* Pass 5 might be empty */
1113 {
1114 png_push_have_row(png_ptr, NULL);
1115 png_read_push_finish_row(png_ptr);
1116 }
1117
1118 break;
1119 }
1120
1121 case 5:
1122 {
1123 int i;
1124
1125 for (i = 0; i < 2 && png_ptr->pass == 5; i++)
1126 {
1127 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1128 png_read_push_finish_row(png_ptr);
1129 }
1130
1131 if (png_ptr->pass == 6) /* Skip top generated row */
1132 {
1133 png_push_have_row(png_ptr, NULL);
1134 png_read_push_finish_row(png_ptr);
1135 }
1136
1137 break;
1138 }
1139
1140 default:
1141 case 6:
1142 {
1143 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1144 png_read_push_finish_row(png_ptr);
1145
1146 if (png_ptr->pass != 6)
1147 break;
1148
1149 png_push_have_row(png_ptr, NULL);
1150 png_read_push_finish_row(png_ptr);
1151 }
1152 }
1153 }
1154 else
1155 #endif
1156 {
1157 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1158 png_read_push_finish_row(png_ptr);
1159 }
1160 }
1161
1162 void /* PRIVATE */
png_read_push_finish_row(png_structrp png_ptr)1163 png_read_push_finish_row(png_structrp png_ptr)
1164 {
1165 #ifdef PNG_READ_INTERLACING_SUPPORTED
1166 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1167
1168 /* Start of interlace block */
1169 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
1170
1171 /* Offset to next interlace block */
1172 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
1173
1174 /* Start of interlace block in the y direction */
1175 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
1176
1177 /* Offset to next interlace block in the y direction */
1178 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
1179
1180 /* Height of interlace block. This is not currently used - if you need
1181 * it, uncomment it here and in png.h
1182 static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
1183 */
1184 #endif
1185
1186 png_ptr->row_number++;
1187 if (png_ptr->row_number < png_ptr->num_rows)
1188 return;
1189
1190 #ifdef PNG_READ_INTERLACING_SUPPORTED
1191 if (png_ptr->interlaced)
1192 {
1193 png_ptr->row_number = 0;
1194 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
1195
1196 do
1197 {
1198 png_ptr->pass++;
1199 if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1200 (png_ptr->pass == 3 && png_ptr->width < 3) ||
1201 (png_ptr->pass == 5 && png_ptr->width < 2))
1202 png_ptr->pass++;
1203
1204 if (png_ptr->pass > 7)
1205 png_ptr->pass--;
1206
1207 if (png_ptr->pass >= 7)
1208 break;
1209
1210 png_ptr->iwidth = (png_ptr->width +
1211 png_pass_inc[png_ptr->pass] - 1 -
1212 png_pass_start[png_ptr->pass]) /
1213 png_pass_inc[png_ptr->pass];
1214
1215 if (png_ptr->transformations & PNG_INTERLACE)
1216 break;
1217
1218 png_ptr->num_rows = (png_ptr->height +
1219 png_pass_yinc[png_ptr->pass] - 1 -
1220 png_pass_ystart[png_ptr->pass]) /
1221 png_pass_yinc[png_ptr->pass];
1222
1223 } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1224 }
1225 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1226 }
1227
1228 void /* PRIVATE */
png_push_have_info(png_structrp png_ptr,png_inforp info_ptr)1229 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1230 {
1231 if (png_ptr->info_fn != NULL)
1232 (*(png_ptr->info_fn))(png_ptr, info_ptr);
1233 }
1234
1235 void /* PRIVATE */
png_push_have_end(png_structrp png_ptr,png_inforp info_ptr)1236 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1237 {
1238 if (png_ptr->end_fn != NULL)
1239 (*(png_ptr->end_fn))(png_ptr, info_ptr);
1240 }
1241
1242 void /* PRIVATE */
png_push_have_row(png_structrp png_ptr,png_bytep row)1243 png_push_have_row(png_structrp png_ptr, png_bytep row)
1244 {
1245 if (png_ptr->row_fn != NULL)
1246 (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1247 (int)png_ptr->pass);
1248 }
1249
1250 #ifdef PNG_READ_INTERLACING_SUPPORTED
1251 void PNGAPI
png_progressive_combine_row(png_const_structrp png_ptr,png_bytep old_row,png_const_bytep new_row)1252 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1253 png_const_bytep new_row)
1254 {
1255 if (png_ptr == NULL)
1256 return;
1257
1258 /* new_row is a flag here - if it is NULL then the app callback was called
1259 * from an empty row (see the calls to png_struct::row_fn below), otherwise
1260 * it must be png_ptr->row_buf+1
1261 */
1262 if (new_row != NULL)
1263 png_combine_row(png_ptr, old_row, 1/*display*/);
1264 }
1265 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1266
1267 void PNGAPI
png_set_progressive_read_fn(png_structrp png_ptr,png_voidp progressive_ptr,png_progressive_info_ptr info_fn,png_progressive_row_ptr row_fn,png_progressive_end_ptr end_fn)1268 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1269 png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1270 png_progressive_end_ptr end_fn)
1271 {
1272 if (png_ptr == NULL)
1273 return;
1274
1275 png_ptr->info_fn = info_fn;
1276 png_ptr->row_fn = row_fn;
1277 png_ptr->end_fn = end_fn;
1278
1279 png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1280 }
1281
1282 png_voidp PNGAPI
png_get_progressive_ptr(png_const_structrp png_ptr)1283 png_get_progressive_ptr(png_const_structrp png_ptr)
1284 {
1285 if (png_ptr == NULL)
1286 return (NULL);
1287
1288 return png_ptr->io_ptr;
1289 }
1290 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1291