1
2 /* pngpread.c - read a png file in push mode
3 *
4 * Copyright (c) 2018 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * 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 \
29 if (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) \
32 if (png_ptr->buffer_size < N) \
33 { png_push_save_buffer(png_ptr); return; }
34
35 void PNGAPI
36 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
37 png_bytep buffer, 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
50 size_t PNGAPI
51 png_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 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
77 png_uint_32 PNGAPI
78 png_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 */
93 void /* PRIVATE */
94 png_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 */
133 void /* PRIVATE */
134 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
135 {
136 size_t num_checked = png_ptr->sig_bytes; /* SAFE, does not exceed 8 */
137 size_t 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
166 void /* PRIVATE */
167 png_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_check_chunk_length(png_ptr, png_ptr->push_length);
193 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
194 }
195
196 chunk_name = png_ptr->chunk_name;
197
198 if (chunk_name == png_IDAT)
199 {
200 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
201 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
202
203 /* If we reach an IDAT chunk, this means we have read all of the
204 * header chunks, and we can start reading the image (or if this
205 * is called after the image has been read - we have an error).
206 */
207 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
208 png_error(png_ptr, "Missing IHDR before IDAT");
209
210 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
211 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
212 png_error(png_ptr, "Missing PLTE before IDAT");
213
214 png_ptr->process_mode = PNG_READ_IDAT_MODE;
215
216 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
217 if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
218 if (png_ptr->push_length == 0)
219 return;
220
221 png_ptr->mode |= PNG_HAVE_IDAT;
222
223 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
224 png_benign_error(png_ptr, "Too many IDATs found");
225 }
226
227 if (chunk_name == png_IHDR)
228 {
229 if (png_ptr->push_length != 13)
230 png_error(png_ptr, "Invalid IHDR length");
231
232 PNG_PUSH_SAVE_BUFFER_IF_FULL
233 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
234 }
235
236 else if (chunk_name == png_IEND)
237 {
238 PNG_PUSH_SAVE_BUFFER_IF_FULL
239 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
240
241 png_ptr->process_mode = PNG_READ_DONE_MODE;
242 png_push_have_end(png_ptr, info_ptr);
243 }
244
245 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
246 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
247 {
248 PNG_PUSH_SAVE_BUFFER_IF_FULL
249 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
250
251 if (chunk_name == png_PLTE)
252 png_ptr->mode |= PNG_HAVE_PLTE;
253 }
254 #endif
255
256 else if (chunk_name == png_PLTE)
257 {
258 PNG_PUSH_SAVE_BUFFER_IF_FULL
259 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
260 }
261
262 else if (chunk_name == png_IDAT)
263 {
264 png_ptr->idat_size = png_ptr->push_length;
265 png_ptr->process_mode = PNG_READ_IDAT_MODE;
266 png_push_have_info(png_ptr, info_ptr);
267 png_ptr->zstream.avail_out =
268 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
269 png_ptr->iwidth) + 1;
270 png_ptr->zstream.next_out = png_ptr->row_buf;
271 return;
272 }
273
274 #ifdef PNG_READ_gAMA_SUPPORTED
275 else if (png_ptr->chunk_name == png_gAMA)
276 {
277 PNG_PUSH_SAVE_BUFFER_IF_FULL
278 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
279 }
280
281 #endif
282 #ifdef PNG_READ_sBIT_SUPPORTED
283 else if (png_ptr->chunk_name == png_sBIT)
284 {
285 PNG_PUSH_SAVE_BUFFER_IF_FULL
286 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
287 }
288
289 #endif
290 #ifdef PNG_READ_cHRM_SUPPORTED
291 else if (png_ptr->chunk_name == png_cHRM)
292 {
293 PNG_PUSH_SAVE_BUFFER_IF_FULL
294 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
295 }
296
297 #endif
298 #ifdef PNG_READ_sRGB_SUPPORTED
299 else if (chunk_name == png_sRGB)
300 {
301 PNG_PUSH_SAVE_BUFFER_IF_FULL
302 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
303 }
304
305 #endif
306 #ifdef PNG_READ_iCCP_SUPPORTED
307 else if (png_ptr->chunk_name == png_iCCP)
308 {
309 PNG_PUSH_SAVE_BUFFER_IF_FULL
310 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
311 }
312
313 #endif
314 #ifdef PNG_READ_sPLT_SUPPORTED
315 else if (chunk_name == png_sPLT)
316 {
317 PNG_PUSH_SAVE_BUFFER_IF_FULL
318 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
319 }
320
321 #endif
322 #ifdef PNG_READ_tRNS_SUPPORTED
323 else if (chunk_name == png_tRNS)
324 {
325 PNG_PUSH_SAVE_BUFFER_IF_FULL
326 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
327 }
328
329 #endif
330 #ifdef PNG_READ_bKGD_SUPPORTED
331 else if (chunk_name == png_bKGD)
332 {
333 PNG_PUSH_SAVE_BUFFER_IF_FULL
334 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
335 }
336
337 #endif
338 #ifdef PNG_READ_hIST_SUPPORTED
339 else if (chunk_name == png_hIST)
340 {
341 PNG_PUSH_SAVE_BUFFER_IF_FULL
342 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
343 }
344
345 #endif
346 #ifdef PNG_READ_pHYs_SUPPORTED
347 else if (chunk_name == png_pHYs)
348 {
349 PNG_PUSH_SAVE_BUFFER_IF_FULL
350 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
351 }
352
353 #endif
354 #ifdef PNG_READ_oFFs_SUPPORTED
355 else if (chunk_name == png_oFFs)
356 {
357 PNG_PUSH_SAVE_BUFFER_IF_FULL
358 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
359 }
360 #endif
361
362 #ifdef PNG_READ_pCAL_SUPPORTED
363 else if (chunk_name == png_pCAL)
364 {
365 PNG_PUSH_SAVE_BUFFER_IF_FULL
366 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
367 }
368
369 #endif
370 #ifdef PNG_READ_sCAL_SUPPORTED
371 else if (chunk_name == png_sCAL)
372 {
373 PNG_PUSH_SAVE_BUFFER_IF_FULL
374 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
375 }
376
377 #endif
378 #ifdef PNG_READ_tIME_SUPPORTED
379 else if (chunk_name == png_tIME)
380 {
381 PNG_PUSH_SAVE_BUFFER_IF_FULL
382 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
383 }
384
385 #endif
386 #ifdef PNG_READ_tEXt_SUPPORTED
387 else if (chunk_name == png_tEXt)
388 {
389 PNG_PUSH_SAVE_BUFFER_IF_FULL
390 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
391 }
392
393 #endif
394 #ifdef PNG_READ_zTXt_SUPPORTED
395 else if (chunk_name == png_zTXt)
396 {
397 PNG_PUSH_SAVE_BUFFER_IF_FULL
398 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
399 }
400
401 #endif
402 #ifdef PNG_READ_iTXt_SUPPORTED
403 else if (chunk_name == png_iTXt)
404 {
405 PNG_PUSH_SAVE_BUFFER_IF_FULL
406 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
407 }
408 #endif
409
410 else
411 {
412 PNG_PUSH_SAVE_BUFFER_IF_FULL
413 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
414 PNG_HANDLE_CHUNK_AS_DEFAULT);
415 }
416
417 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
418 }
419
420 void PNGCBAPI
421 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, size_t length)
422 {
423 png_bytep ptr;
424
425 if (png_ptr == NULL)
426 return;
427
428 ptr = buffer;
429 if (png_ptr->save_buffer_size != 0)
430 {
431 size_t save_size;
432
433 if (length < png_ptr->save_buffer_size)
434 save_size = length;
435
436 else
437 save_size = png_ptr->save_buffer_size;
438
439 memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
440 length -= save_size;
441 ptr += save_size;
442 png_ptr->buffer_size -= save_size;
443 png_ptr->save_buffer_size -= save_size;
444 png_ptr->save_buffer_ptr += save_size;
445 }
446 if (length != 0 && png_ptr->current_buffer_size != 0)
447 {
448 size_t save_size;
449
450 if (length < png_ptr->current_buffer_size)
451 save_size = length;
452
453 else
454 save_size = png_ptr->current_buffer_size;
455
456 memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
457 png_ptr->buffer_size -= save_size;
458 png_ptr->current_buffer_size -= save_size;
459 png_ptr->current_buffer_ptr += save_size;
460 }
461 }
462
463 void /* PRIVATE */
464 png_push_save_buffer(png_structrp png_ptr)
465 {
466 if (png_ptr->save_buffer_size != 0)
467 {
468 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
469 {
470 size_t i, istop;
471 png_bytep sp;
472 png_bytep dp;
473
474 istop = png_ptr->save_buffer_size;
475 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
476 i < istop; i++, sp++, dp++)
477 {
478 *dp = *sp;
479 }
480 }
481 }
482 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
483 png_ptr->save_buffer_max)
484 {
485 size_t new_max;
486 png_bytep old_buffer;
487
488 if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
489 (png_ptr->current_buffer_size + 256))
490 {
491 png_error(png_ptr, "Potential overflow of save_buffer");
492 }
493
494 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
495 old_buffer = png_ptr->save_buffer;
496 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
497 (size_t)new_max);
498
499 if (png_ptr->save_buffer == NULL)
500 {
501 png_free(png_ptr, old_buffer);
502 png_error(png_ptr, "Insufficient memory for save_buffer");
503 }
504
505 if (old_buffer)
506 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
507 else if (png_ptr->save_buffer_size)
508 png_error(png_ptr, "save_buffer error");
509 png_free(png_ptr, old_buffer);
510 png_ptr->save_buffer_max = new_max;
511 }
512 if (png_ptr->current_buffer_size)
513 {
514 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
515 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
516 png_ptr->save_buffer_size += png_ptr->current_buffer_size;
517 png_ptr->current_buffer_size = 0;
518 }
519 png_ptr->save_buffer_ptr = png_ptr->save_buffer;
520 png_ptr->buffer_size = 0;
521 }
522
523 void /* PRIVATE */
524 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
525 size_t buffer_length)
526 {
527 png_ptr->current_buffer = buffer;
528 png_ptr->current_buffer_size = buffer_length;
529 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
530 png_ptr->current_buffer_ptr = png_ptr->current_buffer;
531 }
532
533 void /* PRIVATE */
534 png_push_read_IDAT(png_structrp png_ptr)
535 {
536 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
537 {
538 png_byte chunk_length[4];
539 png_byte chunk_tag[4];
540
541 /* TODO: this code can be commoned up with the same code in push_read */
542 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
543 png_push_fill_buffer(png_ptr, chunk_length, 4);
544 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
545 png_reset_crc(png_ptr);
546 png_crc_read(png_ptr, chunk_tag, 4);
547 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
548 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
549
550 if (png_ptr->chunk_name != png_IDAT)
551 {
552 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
553
554 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
555 png_error(png_ptr, "Not enough compressed data");
556
557 return;
558 }
559
560 png_ptr->idat_size = png_ptr->push_length;
561 }
562
563 if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
564 {
565 size_t save_size = png_ptr->save_buffer_size;
566 png_uint_32 idat_size = png_ptr->idat_size;
567
568 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
569 * are of different types and we don't know which variable has the fewest
570 * bits. Carefully select the smaller and cast it to the type of the
571 * larger - this cannot overflow. Do not cast in the following test - it
572 * will break on either 16-bit or 64-bit platforms.
573 */
574 if (idat_size < save_size)
575 save_size = (size_t)idat_size;
576
577 else
578 idat_size = (png_uint_32)save_size;
579
580 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
581
582 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
583
584 png_ptr->idat_size -= idat_size;
585 png_ptr->buffer_size -= save_size;
586 png_ptr->save_buffer_size -= save_size;
587 png_ptr->save_buffer_ptr += save_size;
588 }
589
590 if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
591 {
592 size_t save_size = png_ptr->current_buffer_size;
593 png_uint_32 idat_size = png_ptr->idat_size;
594
595 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
596 * are of different types and we don't know which variable has the fewest
597 * bits. Carefully select the smaller and cast it to the type of the
598 * larger - this cannot overflow.
599 */
600 if (idat_size < save_size)
601 save_size = (size_t)idat_size;
602
603 else
604 idat_size = (png_uint_32)save_size;
605
606 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
607
608 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
609
610 png_ptr->idat_size -= idat_size;
611 png_ptr->buffer_size -= save_size;
612 png_ptr->current_buffer_size -= save_size;
613 png_ptr->current_buffer_ptr += save_size;
614 }
615
616 if (png_ptr->idat_size == 0)
617 {
618 PNG_PUSH_SAVE_BUFFER_IF_LT(4)
619 png_crc_finish(png_ptr, 0);
620 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
621 png_ptr->mode |= PNG_AFTER_IDAT;
622 png_ptr->zowner = 0;
623 }
624 }
625
626 void /* PRIVATE */
627 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
628 size_t buffer_length)
629 {
630 /* The caller checks for a non-zero buffer length. */
631 if (!(buffer_length > 0) || buffer == NULL)
632 png_error(png_ptr, "No IDAT data (internal error)");
633
634 /* This routine must process all the data it has been given
635 * before returning, calling the row callback as required to
636 * handle the uncompressed results.
637 */
638 png_ptr->zstream.next_in = buffer;
639 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
640 png_ptr->zstream.avail_in = (uInt)buffer_length;
641
642 /* Keep going until the decompressed data is all processed
643 * or the stream marked as finished.
644 */
645 while (png_ptr->zstream.avail_in > 0 &&
646 (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
647 {
648 int ret;
649
650 /* We have data for zlib, but we must check that zlib
651 * has someplace to put the results. It doesn't matter
652 * if we don't expect any results -- it may be the input
653 * data is just the LZ end code.
654 */
655 if (!(png_ptr->zstream.avail_out > 0))
656 {
657 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
658 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
659 png_ptr->iwidth) + 1);
660
661 png_ptr->zstream.next_out = png_ptr->row_buf;
662 }
663
664 /* Using Z_SYNC_FLUSH here means that an unterminated
665 * LZ stream (a stream with a missing end code) can still
666 * be handled, otherwise (Z_NO_FLUSH) a future zlib
667 * implementation might defer output and therefore
668 * change the current behavior (see comments in inflate.c
669 * for why this doesn't happen at present with zlib 1.2.5).
670 */
671 ret = PNG_INFLATE(png_ptr, Z_SYNC_FLUSH);
672
673 /* Check for any failure before proceeding. */
674 if (ret != Z_OK && ret != Z_STREAM_END)
675 {
676 /* Terminate the decompression. */
677 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
678 png_ptr->zowner = 0;
679
680 /* This may be a truncated stream (missing or
681 * damaged end code). Treat that as a warning.
682 */
683 if (png_ptr->row_number >= png_ptr->num_rows ||
684 png_ptr->pass > 6)
685 png_warning(png_ptr, "Truncated compressed data in IDAT");
686
687 else
688 {
689 if (ret == Z_DATA_ERROR)
690 png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
691 else
692 png_error(png_ptr, "Decompression error in IDAT");
693 }
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
738 void /* PRIVATE */
739 png_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
968 void /* PRIVATE */
969 png_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 const png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
976
977 /* Offset to next interlace block */
978 static 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 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 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 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
1034 void /* PRIVATE */
1035 png_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
1041 void /* PRIVATE */
1042 png_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
1048 void /* PRIVATE */
1049 png_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
1057 void PNGAPI
1058 png_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
1073 void PNGAPI
1074 png_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
1088 png_voidp PNGAPI
1089 png_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 */