2 /* pngpread.c - read a png file in push mode
4 * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
5 * Copyright (c) 1998-2014 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.)
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
16 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
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_SKIP_MODE 3
23 #define PNG_READ_tEXt_MODE 4
24 #define PNG_READ_zTXt_MODE 5
25 #define PNG_READ_DONE_MODE 6
26 #define PNG_READ_iTXt_MODE 7
27 #define PNG_ERROR_MODE 8
30 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
31 png_bytep buffer, png_size_t buffer_size)
33 if (png_ptr == NULL || info_ptr == NULL)
36 png_push_restore_buffer(png_ptr, buffer, buffer_size);
38 while (png_ptr->buffer_size)
40 png_process_some_data(png_ptr, info_ptr);
45 png_process_data_pause(png_structrp png_ptr, int save)
49 /* It's easiest for the caller if we do the save, then the caller doesn't
50 * have to supply the same data again:
53 png_push_save_buffer(png_ptr);
56 /* This includes any pending saved bytes: */
57 png_size_t remaining = png_ptr->buffer_size;
58 png_ptr->buffer_size = 0;
60 /* So subtract the saved buffer size, unless all the data
61 * is actually 'saved', in which case we just return 0
63 if (png_ptr->save_buffer_size < remaining)
64 return remaining - png_ptr->save_buffer_size;
72 png_process_data_skip(png_structrp png_ptr)
74 png_uint_32 remaining = 0;
76 if (png_ptr != NULL && png_ptr->process_mode == PNG_SKIP_MODE &&
77 png_ptr->skip_length > 0)
79 /* At the end of png_process_data the buffer size must be 0 (see the loop
80 * above) so we can detect a broken call here:
82 if (png_ptr->buffer_size != 0)
84 "png_process_data_skip called inside png_process_data");
86 /* If is impossible for there to be a saved buffer at this point -
87 * otherwise we could not be in SKIP mode. This will also happen if
88 * png_process_skip is called inside png_process_data (but only very
91 if (png_ptr->save_buffer_size != 0)
92 png_error(png_ptr, "png_process_data_skip called with saved data");
94 remaining = png_ptr->skip_length;
95 png_ptr->skip_length = 0;
96 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
102 /* What we do with the incoming data depends on what we were previously
103 * doing before we ran out of data...
106 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
111 switch (png_ptr->process_mode)
113 case PNG_READ_SIG_MODE:
115 png_push_read_sig(png_ptr, info_ptr);
119 case PNG_READ_CHUNK_MODE:
121 png_push_read_chunk(png_ptr, info_ptr);
125 case PNG_READ_IDAT_MODE:
127 png_push_read_IDAT(png_ptr);
133 png_push_crc_finish(png_ptr);
139 png_ptr->buffer_size = 0;
145 /* Read any remaining signature bytes from the stream and compare them with
146 * the correct PNG signature. It is possible that this routine is called
147 * with bytes already read from the signature, either because they have been
148 * checked by the calling application, or because of multiple calls to this
152 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
154 png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
155 num_to_check = 8 - num_checked;
157 if (png_ptr->buffer_size < num_to_check)
159 num_to_check = png_ptr->buffer_size;
162 png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
164 png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
166 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
168 if (num_checked < 4 &&
169 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
170 png_error(png_ptr, "Not a PNG file");
173 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
177 if (png_ptr->sig_bytes >= 8)
179 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
185 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
187 png_uint_32 chunk_name;
188 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
189 int keep; /* unknown handling method */
192 /* First we make sure we have enough data for the 4 byte chunk name
193 * and the 4 byte chunk length before proceeding with decoding the
194 * chunk data. To fully decode each of these chunks, we also make
195 * sure we have enough data in the buffer for the 4 byte CRC at the
196 * end of every chunk (except IDAT, which is handled separately).
198 if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
200 png_byte chunk_length[4];
201 png_byte chunk_tag[4];
203 if (png_ptr->buffer_size < 8)
205 png_push_save_buffer(png_ptr);
209 png_push_fill_buffer(png_ptr, chunk_length, 4);
210 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
211 png_reset_crc(png_ptr);
212 png_crc_read(png_ptr, chunk_tag, 4);
213 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
214 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
215 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
218 chunk_name = png_ptr->chunk_name;
220 if (chunk_name == png_IDAT)
222 if (png_ptr->mode & PNG_AFTER_IDAT)
223 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
225 /* If we reach an IDAT chunk, this means we have read all of the
226 * header chunks, and we can start reading the image (or if this
227 * is called after the image has been read - we have an error).
229 if (!(png_ptr->mode & PNG_HAVE_IHDR))
230 png_error(png_ptr, "Missing IHDR before IDAT");
232 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
233 !(png_ptr->mode & PNG_HAVE_PLTE))
234 png_error(png_ptr, "Missing PLTE before IDAT");
236 png_ptr->mode |= PNG_HAVE_IDAT;
238 if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
239 if (png_ptr->push_length == 0)
242 if (png_ptr->mode & PNG_AFTER_IDAT)
243 png_benign_error(png_ptr, "Too many IDATs found[p]");
246 if (chunk_name == png_IHDR)
248 if (png_ptr->push_length != 13)
249 png_error(png_ptr, "Invalid IHDR length");
251 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
253 png_push_save_buffer(png_ptr);
257 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
260 else if (chunk_name == png_IEND)
262 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
264 png_push_save_buffer(png_ptr);
268 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
270 png_ptr->process_mode = PNG_READ_DONE_MODE;
271 png_push_have_end(png_ptr, info_ptr);
274 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
275 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
277 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
279 png_push_save_buffer(png_ptr);
283 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
285 if (chunk_name == png_PLTE)
286 png_ptr->mode |= PNG_HAVE_PLTE;
290 else if (chunk_name == png_PLTE)
292 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
294 png_push_save_buffer(png_ptr);
297 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
300 else if (chunk_name == png_IDAT)
302 png_ptr->idat_size = png_ptr->push_length;
303 png_ptr->process_mode = PNG_READ_IDAT_MODE;
304 png_push_have_info(png_ptr, info_ptr);
305 png_ptr->zstream.avail_out =
306 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
307 png_ptr->iwidth) + 1;
308 png_ptr->zstream.next_out = png_ptr->row_buf;
312 #ifdef PNG_READ_gAMA_SUPPORTED
313 else if (png_ptr->chunk_name == png_gAMA)
315 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
317 png_push_save_buffer(png_ptr);
321 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
325 #ifdef PNG_READ_sBIT_SUPPORTED
326 else if (png_ptr->chunk_name == png_sBIT)
328 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
330 png_push_save_buffer(png_ptr);
334 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
338 #ifdef PNG_READ_cHRM_SUPPORTED
339 else if (png_ptr->chunk_name == png_cHRM)
341 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
343 png_push_save_buffer(png_ptr);
347 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
351 #ifdef PNG_READ_sRGB_SUPPORTED
352 else if (chunk_name == png_sRGB)
354 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
356 png_push_save_buffer(png_ptr);
360 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
364 #ifdef PNG_READ_iCCP_SUPPORTED
365 else if (png_ptr->chunk_name == png_iCCP)
367 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
369 png_push_save_buffer(png_ptr);
373 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
377 #ifdef PNG_READ_sPLT_SUPPORTED
378 else if (chunk_name == png_sPLT)
380 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
382 png_push_save_buffer(png_ptr);
386 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
390 #ifdef PNG_READ_tRNS_SUPPORTED
391 else if (chunk_name == png_tRNS)
393 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
395 png_push_save_buffer(png_ptr);
399 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
403 #ifdef PNG_READ_bKGD_SUPPORTED
404 else if (chunk_name == png_bKGD)
406 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
408 png_push_save_buffer(png_ptr);
412 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
416 #ifdef PNG_READ_hIST_SUPPORTED
417 else if (chunk_name == png_hIST)
419 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
421 png_push_save_buffer(png_ptr);
425 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
429 #ifdef PNG_READ_pHYs_SUPPORTED
430 else if (chunk_name == png_pHYs)
432 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
434 png_push_save_buffer(png_ptr);
438 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
442 #ifdef PNG_READ_oFFs_SUPPORTED
443 else if (chunk_name == png_oFFs)
445 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
447 png_push_save_buffer(png_ptr);
451 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
455 #ifdef PNG_READ_pCAL_SUPPORTED
456 else if (chunk_name == png_pCAL)
458 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
460 png_push_save_buffer(png_ptr);
464 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
468 #ifdef PNG_READ_sCAL_SUPPORTED
469 else if (chunk_name == png_sCAL)
471 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
473 png_push_save_buffer(png_ptr);
477 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
481 #ifdef PNG_READ_tIME_SUPPORTED
482 else if (chunk_name == png_tIME)
484 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
486 png_push_save_buffer(png_ptr);
490 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
494 #ifdef PNG_READ_tEXt_SUPPORTED
495 else if (chunk_name == png_tEXt)
497 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
499 png_push_save_buffer(png_ptr);
503 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
507 #ifdef PNG_READ_zTXt_SUPPORTED
508 else if (chunk_name == png_zTXt)
510 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
512 png_push_save_buffer(png_ptr);
516 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
520 #ifdef PNG_READ_iTXt_SUPPORTED
521 else if (chunk_name == png_iTXt)
523 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
525 png_push_save_buffer(png_ptr);
529 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
535 if (png_ptr->push_length + 4 > png_ptr->buffer_size)
537 png_push_save_buffer(png_ptr);
540 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
541 PNG_HANDLE_CHUNK_AS_DEFAULT);
544 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
548 png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
550 png_ptr->process_mode = PNG_SKIP_MODE;
551 png_ptr->skip_length = skip;
555 png_push_crc_finish(png_structrp png_ptr)
557 if (png_ptr->skip_length && png_ptr->save_buffer_size)
559 png_size_t save_size = png_ptr->save_buffer_size;
560 png_uint_32 skip_length = png_ptr->skip_length;
562 /* We want the smaller of 'skip_length' and 'save_buffer_size', but
563 * they are of different types and we don't know which variable has the
564 * fewest bits. Carefully select the smaller and cast it to the type of
565 * the larger - this cannot overflow. Do not cast in the following test
566 * - it will break on either 16 or 64 bit platforms.
568 if (skip_length < save_size)
569 save_size = (png_size_t)skip_length;
572 skip_length = (png_uint_32)save_size;
574 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
576 png_ptr->skip_length -= skip_length;
577 png_ptr->buffer_size -= save_size;
578 png_ptr->save_buffer_size -= save_size;
579 png_ptr->save_buffer_ptr += save_size;
581 if (png_ptr->skip_length && png_ptr->current_buffer_size)
583 png_size_t save_size = png_ptr->current_buffer_size;
584 png_uint_32 skip_length = png_ptr->skip_length;
586 /* We want the smaller of 'skip_length' and 'current_buffer_size', here,
587 * the same problem exists as above and the same solution.
589 if (skip_length < save_size)
590 save_size = (png_size_t)skip_length;
593 skip_length = (png_uint_32)save_size;
595 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
597 png_ptr->skip_length -= skip_length;
598 png_ptr->buffer_size -= save_size;
599 png_ptr->current_buffer_size -= save_size;
600 png_ptr->current_buffer_ptr += save_size;
602 if (!png_ptr->skip_length)
604 if (png_ptr->buffer_size < 4)
606 png_push_save_buffer(png_ptr);
610 png_crc_finish(png_ptr, 0);
611 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
616 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
624 if (png_ptr->save_buffer_size)
626 png_size_t save_size;
628 if (length < png_ptr->save_buffer_size)
632 save_size = png_ptr->save_buffer_size;
634 memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
637 png_ptr->buffer_size -= save_size;
638 png_ptr->save_buffer_size -= save_size;
639 png_ptr->save_buffer_ptr += save_size;
641 if (length && png_ptr->current_buffer_size)
643 png_size_t save_size;
645 if (length < png_ptr->current_buffer_size)
649 save_size = png_ptr->current_buffer_size;
651 memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
652 png_ptr->buffer_size -= save_size;
653 png_ptr->current_buffer_size -= save_size;
654 png_ptr->current_buffer_ptr += save_size;
659 png_push_save_buffer(png_structrp png_ptr)
661 if (png_ptr->save_buffer_size)
663 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
669 istop = png_ptr->save_buffer_size;
670 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
671 i < istop; i++, sp++, dp++)
677 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
678 png_ptr->save_buffer_max)
681 png_bytep old_buffer;
683 if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
684 (png_ptr->current_buffer_size + 256))
686 png_error(png_ptr, "Potential overflow of save_buffer");
689 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
690 old_buffer = png_ptr->save_buffer;
691 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
692 (png_size_t)new_max);
694 if (png_ptr->save_buffer == NULL)
696 png_free(png_ptr, old_buffer);
697 png_error(png_ptr, "Insufficient memory for save_buffer");
700 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
701 png_free(png_ptr, old_buffer);
702 png_ptr->save_buffer_max = new_max;
704 if (png_ptr->current_buffer_size)
706 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
707 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
708 png_ptr->save_buffer_size += png_ptr->current_buffer_size;
709 png_ptr->current_buffer_size = 0;
711 png_ptr->save_buffer_ptr = png_ptr->save_buffer;
712 png_ptr->buffer_size = 0;
716 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
717 png_size_t buffer_length)
719 png_ptr->current_buffer = buffer;
720 png_ptr->current_buffer_size = buffer_length;
721 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
722 png_ptr->current_buffer_ptr = png_ptr->current_buffer;
726 png_push_read_IDAT(png_structrp png_ptr)
728 if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
730 png_byte chunk_length[4];
731 png_byte chunk_tag[4];
733 /* TODO: this code can be commoned up with the same code in push_read */
734 if (png_ptr->buffer_size < 8)
736 png_push_save_buffer(png_ptr);
740 png_push_fill_buffer(png_ptr, chunk_length, 4);
741 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
742 png_reset_crc(png_ptr);
743 png_crc_read(png_ptr, chunk_tag, 4);
744 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
745 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
747 if (png_ptr->chunk_name != png_IDAT)
749 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
751 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
752 png_error(png_ptr, "Not enough compressed data");
757 png_ptr->idat_size = png_ptr->push_length;
760 if (png_ptr->idat_size && png_ptr->save_buffer_size)
762 png_size_t save_size = png_ptr->save_buffer_size;
763 png_uint_32 idat_size = png_ptr->idat_size;
765 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
766 * are of different types and we don't know which variable has the fewest
767 * bits. Carefully select the smaller and cast it to the type of the
768 * larger - this cannot overflow. Do not cast in the following test - it
769 * will break on either 16 or 64 bit platforms.
771 if (idat_size < save_size)
772 save_size = (png_size_t)idat_size;
775 idat_size = (png_uint_32)save_size;
777 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
779 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
781 png_ptr->idat_size -= idat_size;
782 png_ptr->buffer_size -= save_size;
783 png_ptr->save_buffer_size -= save_size;
784 png_ptr->save_buffer_ptr += save_size;
787 if (png_ptr->idat_size && png_ptr->current_buffer_size)
789 png_size_t save_size = png_ptr->current_buffer_size;
790 png_uint_32 idat_size = png_ptr->idat_size;
792 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
793 * are of different types and we don't know which variable has the fewest
794 * bits. Carefully select the smaller and cast it to the type of the
795 * larger - this cannot overflow.
797 if (idat_size < save_size)
798 save_size = (png_size_t)idat_size;
801 idat_size = (png_uint_32)save_size;
803 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
805 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
807 png_ptr->idat_size -= idat_size;
808 png_ptr->buffer_size -= save_size;
809 png_ptr->current_buffer_size -= save_size;
810 png_ptr->current_buffer_ptr += save_size;
812 if (!png_ptr->idat_size)
814 if (png_ptr->buffer_size < 4)
816 png_push_save_buffer(png_ptr);
820 png_crc_finish(png_ptr, 0);
821 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
822 png_ptr->mode |= PNG_AFTER_IDAT;
828 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
829 png_size_t buffer_length)
831 /* The caller checks for a non-zero buffer length. */
832 if (!(buffer_length > 0) || buffer == NULL)
833 png_error(png_ptr, "No IDAT data (internal error)");
835 /* This routine must process all the data it has been given
836 * before returning, calling the row callback as required to
837 * handle the uncompressed results.
839 png_ptr->zstream.next_in = buffer;
840 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
841 png_ptr->zstream.avail_in = (uInt)buffer_length;
843 /* Keep going until the decompressed data is all processed
844 * or the stream marked as finished.
846 while (png_ptr->zstream.avail_in > 0 &&
847 !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
851 /* We have data for zlib, but we must check that zlib
852 * has someplace to put the results. It doesn't matter
853 * if we don't expect any results -- it may be the input
854 * data is just the LZ end code.
856 if (!(png_ptr->zstream.avail_out > 0))
858 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
859 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
860 png_ptr->iwidth) + 1);
862 png_ptr->zstream.next_out = png_ptr->row_buf;
865 /* Using Z_SYNC_FLUSH here means that an unterminated
866 * LZ stream (a stream with a missing end code) can still
867 * be handled, otherwise (Z_NO_FLUSH) a future zlib
868 * implementation might defer output and therefore
869 * change the current behavior (see comments in inflate.c
870 * for why this doesn't happen at present with zlib 1.2.5).
872 ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
874 /* Check for any failure before proceeding. */
875 if (ret != Z_OK && ret != Z_STREAM_END)
877 /* Terminate the decompression. */
878 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
881 /* This may be a truncated stream (missing or
882 * damaged end code). Treat that as a warning.
884 if (png_ptr->row_number >= png_ptr->num_rows ||
886 png_warning(png_ptr, "Truncated compressed data in IDAT");
889 png_error(png_ptr, "Decompression error in IDAT");
891 /* Skip the check on unprocessed input */
895 /* Did inflate output any data? */
896 if (png_ptr->zstream.next_out != png_ptr->row_buf)
898 /* Is this unexpected data after the last row?
899 * If it is, artificially terminate the LZ output
902 if (png_ptr->row_number >= png_ptr->num_rows ||
906 png_warning(png_ptr, "Extra compressed data in IDAT");
907 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
910 /* Do no more processing; skip the unprocessed
916 /* Do we have a complete row? */
917 if (png_ptr->zstream.avail_out == 0)
918 png_push_process_row(png_ptr);
921 /* And check for the end of the stream. */
922 if (ret == Z_STREAM_END)
923 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
926 /* All the data should have been processed, if anything
927 * is left at this point we have bytes of IDAT data
928 * after the zlib end code.
930 if (png_ptr->zstream.avail_in > 0)
931 png_warning(png_ptr, "Extra compression data in IDAT");
935 png_push_process_row(png_structrp png_ptr)
937 /* 1.5.6: row_info moved out of png_struct to a local here. */
938 png_row_info row_info;
940 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
941 row_info.color_type = png_ptr->color_type;
942 row_info.bit_depth = png_ptr->bit_depth;
943 row_info.channels = png_ptr->channels;
944 row_info.pixel_depth = png_ptr->pixel_depth;
945 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
947 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
949 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
950 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
951 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
953 png_error(png_ptr, "bad adaptive filter value");
956 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
957 * 1.5.6, while the buffer really is this big in current versions of libpng
958 * it may not be in the future, so this was changed just to copy the
959 * interlaced row count:
961 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
963 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
964 if (png_ptr->transformations)
965 png_do_read_transformations(png_ptr, &row_info);
968 /* The transformed pixel depth should match the depth now in row_info. */
969 if (png_ptr->transformed_pixel_depth == 0)
971 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
972 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
973 png_error(png_ptr, "progressive row overflow");
976 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
977 png_error(png_ptr, "internal progressive row size calculation error");
980 #ifdef PNG_READ_INTERLACING_SUPPORTED
981 /* Blow up interlaced rows to full size */
982 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
984 if (png_ptr->pass < 6)
985 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
986 png_ptr->transformations);
988 switch (png_ptr->pass)
993 for (i = 0; i < 8 && png_ptr->pass == 0; i++)
995 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
996 png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
999 if (png_ptr->pass == 2) /* Pass 1 might be empty */
1001 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1003 png_push_have_row(png_ptr, NULL);
1004 png_read_push_finish_row(png_ptr);
1008 if (png_ptr->pass == 4 && png_ptr->height <= 4)
1010 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1012 png_push_have_row(png_ptr, NULL);
1013 png_read_push_finish_row(png_ptr);
1017 if (png_ptr->pass == 6 && png_ptr->height <= 4)
1019 png_push_have_row(png_ptr, NULL);
1020 png_read_push_finish_row(png_ptr);
1029 for (i = 0; i < 8 && png_ptr->pass == 1; i++)
1031 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1032 png_read_push_finish_row(png_ptr);
1035 if (png_ptr->pass == 2) /* Skip top 4 generated rows */
1037 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1039 png_push_have_row(png_ptr, NULL);
1040 png_read_push_finish_row(png_ptr);
1051 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1053 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1054 png_read_push_finish_row(png_ptr);
1057 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
1059 png_push_have_row(png_ptr, NULL);
1060 png_read_push_finish_row(png_ptr);
1063 if (png_ptr->pass == 4) /* Pass 3 might be empty */
1065 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1067 png_push_have_row(png_ptr, NULL);
1068 png_read_push_finish_row(png_ptr);
1079 for (i = 0; i < 4 && png_ptr->pass == 3; i++)
1081 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1082 png_read_push_finish_row(png_ptr);
1085 if (png_ptr->pass == 4) /* Skip top two generated rows */
1087 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1089 png_push_have_row(png_ptr, NULL);
1090 png_read_push_finish_row(png_ptr);
1101 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1103 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1104 png_read_push_finish_row(png_ptr);
1107 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
1109 png_push_have_row(png_ptr, NULL);
1110 png_read_push_finish_row(png_ptr);
1113 if (png_ptr->pass == 6) /* Pass 5 might be empty */
1115 png_push_have_row(png_ptr, NULL);
1116 png_read_push_finish_row(png_ptr);
1126 for (i = 0; i < 2 && png_ptr->pass == 5; i++)
1128 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1129 png_read_push_finish_row(png_ptr);
1132 if (png_ptr->pass == 6) /* Skip top generated row */
1134 png_push_have_row(png_ptr, NULL);
1135 png_read_push_finish_row(png_ptr);
1144 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1145 png_read_push_finish_row(png_ptr);
1147 if (png_ptr->pass != 6)
1150 png_push_have_row(png_ptr, NULL);
1151 png_read_push_finish_row(png_ptr);
1158 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
1159 png_read_push_finish_row(png_ptr);
1164 png_read_push_finish_row(png_structrp png_ptr)
1166 #ifdef PNG_READ_INTERLACING_SUPPORTED
1167 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1169 /* Start of interlace block */
1170 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
1172 /* Offset to next interlace block */
1173 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
1175 /* Start of interlace block in the y direction */
1176 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
1178 /* Offset to next interlace block in the y direction */
1179 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
1181 /* Height of interlace block. This is not currently used - if you need
1182 * it, uncomment it here and in png.h
1183 static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
1187 png_ptr->row_number++;
1188 if (png_ptr->row_number < png_ptr->num_rows)
1191 #ifdef PNG_READ_INTERLACING_SUPPORTED
1192 if (png_ptr->interlaced)
1194 png_ptr->row_number = 0;
1195 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
1200 if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1201 (png_ptr->pass == 3 && png_ptr->width < 3) ||
1202 (png_ptr->pass == 5 && png_ptr->width < 2))
1205 if (png_ptr->pass > 7)
1208 if (png_ptr->pass >= 7)
1211 png_ptr->iwidth = (png_ptr->width +
1212 png_pass_inc[png_ptr->pass] - 1 -
1213 png_pass_start[png_ptr->pass]) /
1214 png_pass_inc[png_ptr->pass];
1216 if (png_ptr->transformations & PNG_INTERLACE)
1219 png_ptr->num_rows = (png_ptr->height +
1220 png_pass_yinc[png_ptr->pass] - 1 -
1221 png_pass_ystart[png_ptr->pass]) /
1222 png_pass_yinc[png_ptr->pass];
1224 } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1226 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1230 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1232 if (png_ptr->info_fn != NULL)
1233 (*(png_ptr->info_fn))(png_ptr, info_ptr);
1237 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1239 if (png_ptr->end_fn != NULL)
1240 (*(png_ptr->end_fn))(png_ptr, info_ptr);
1244 png_push_have_row(png_structrp png_ptr, png_bytep row)
1246 if (png_ptr->row_fn != NULL)
1247 (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1248 (int)png_ptr->pass);
1251 #ifdef PNG_READ_INTERLACING_SUPPORTED
1253 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1254 png_const_bytep new_row)
1256 if (png_ptr == NULL)
1259 /* new_row is a flag here - if it is NULL then the app callback was called
1260 * from an empty row (see the calls to png_struct::row_fn below), otherwise
1261 * it must be png_ptr->row_buf+1
1263 if (new_row != NULL)
1264 png_combine_row(png_ptr, old_row, 1/*display*/);
1266 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1269 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1270 png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1271 png_progressive_end_ptr end_fn)
1273 if (png_ptr == NULL)
1276 png_ptr->info_fn = info_fn;
1277 png_ptr->row_fn = row_fn;
1278 png_ptr->end_fn = end_fn;
1280 png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1284 png_get_progressive_ptr(png_const_structrp png_ptr)
1286 if (png_ptr == NULL)
1289 return png_ptr->io_ptr;
1291 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */