2 /* pngpread.c - read a png file in push mode
4 * Last changed in libpng 1.6.23 [June 9, 2016]
5 * Copyright (c) 1998-2002,2004,2006-2016 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_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
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; }
36 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
37 png_bytep buffer, png_size_t buffer_size)
39 if (png_ptr == NULL || info_ptr == NULL)
42 png_push_restore_buffer(png_ptr, buffer, buffer_size);
44 while (png_ptr->buffer_size)
46 png_process_some_data(png_ptr, info_ptr);
51 png_process_data_pause(png_structrp png_ptr, int save)
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:
59 png_push_save_buffer(png_ptr);
62 /* This includes any pending saved bytes: */
63 png_size_t remaining = png_ptr->buffer_size;
64 png_ptr->buffer_size = 0;
66 /* So subtract the saved buffer size, unless all the data
67 * is actually 'saved', in which case we just return 0
69 if (png_ptr->save_buffer_size < remaining)
70 return remaining - png_ptr->save_buffer_size;
78 png_process_data_skip(png_structrp png_ptr)
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.
85 png_app_warning(png_ptr,
86 "png_process_data_skip is not implemented in any current version of libpng");
90 /* What we do with the incoming data depends on what we were previously
91 * doing before we ran out of data...
94 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
99 switch (png_ptr->process_mode)
101 case PNG_READ_SIG_MODE:
103 png_push_read_sig(png_ptr, info_ptr);
107 case PNG_READ_CHUNK_MODE:
109 png_push_read_chunk(png_ptr, info_ptr);
113 case PNG_READ_IDAT_MODE:
115 png_push_read_IDAT(png_ptr);
121 png_ptr->buffer_size = 0;
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
134 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
136 png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
137 num_to_check = 8 - num_checked;
139 if (png_ptr->buffer_size < num_to_check)
141 num_to_check = png_ptr->buffer_size;
144 png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
146 png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
148 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
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");
155 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
159 if (png_ptr->sig_bytes >= 8)
161 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
167 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
169 png_uint_32 chunk_name;
170 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
171 int keep; /* unknown handling method */
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).
180 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
182 png_byte chunk_length[4];
183 png_byte chunk_tag[4];
185 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
186 png_push_fill_buffer(png_ptr, chunk_length, 4);
187 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
188 png_reset_crc(png_ptr);
189 png_crc_read(png_ptr, chunk_tag, 4);
190 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
191 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
192 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
195 chunk_name = png_ptr->chunk_name;
197 if (chunk_name == png_IDAT)
199 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
200 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
202 /* If we reach an IDAT chunk, this means we have read all of the
203 * header chunks, and we can start reading the image (or if this
204 * is called after the image has been read - we have an error).
206 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
207 png_error(png_ptr, "Missing IHDR before IDAT");
209 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
210 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
211 png_error(png_ptr, "Missing PLTE before IDAT");
213 png_ptr->process_mode = PNG_READ_IDAT_MODE;
215 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
216 if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
217 if (png_ptr->push_length == 0)
220 png_ptr->mode |= PNG_HAVE_IDAT;
222 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
223 png_benign_error(png_ptr, "Too many IDATs found");
226 if (chunk_name == png_IHDR)
228 if (png_ptr->push_length != 13)
229 png_error(png_ptr, "Invalid IHDR length");
231 PNG_PUSH_SAVE_BUFFER_IF_FULL
232 png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
235 else if (chunk_name == png_IEND)
237 PNG_PUSH_SAVE_BUFFER_IF_FULL
238 png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
240 png_ptr->process_mode = PNG_READ_DONE_MODE;
241 png_push_have_end(png_ptr, info_ptr);
244 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
245 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
247 PNG_PUSH_SAVE_BUFFER_IF_FULL
248 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
250 if (chunk_name == png_PLTE)
251 png_ptr->mode |= PNG_HAVE_PLTE;
255 else if (chunk_name == png_PLTE)
257 PNG_PUSH_SAVE_BUFFER_IF_FULL
258 png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
261 else if (chunk_name == png_IDAT)
263 png_ptr->idat_size = png_ptr->push_length;
264 png_ptr->process_mode = PNG_READ_IDAT_MODE;
265 png_push_have_info(png_ptr, info_ptr);
266 png_ptr->zstream.avail_out =
267 (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
268 png_ptr->iwidth) + 1;
269 png_ptr->zstream.next_out = png_ptr->row_buf;
273 #ifdef PNG_READ_gAMA_SUPPORTED
274 else if (png_ptr->chunk_name == png_gAMA)
276 PNG_PUSH_SAVE_BUFFER_IF_FULL
277 png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
281 #ifdef PNG_READ_sBIT_SUPPORTED
282 else if (png_ptr->chunk_name == png_sBIT)
284 PNG_PUSH_SAVE_BUFFER_IF_FULL
285 png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
289 #ifdef PNG_READ_cHRM_SUPPORTED
290 else if (png_ptr->chunk_name == png_cHRM)
292 PNG_PUSH_SAVE_BUFFER_IF_FULL
293 png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
297 #ifdef PNG_READ_sRGB_SUPPORTED
298 else if (chunk_name == png_sRGB)
300 PNG_PUSH_SAVE_BUFFER_IF_FULL
301 png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
305 #ifdef PNG_READ_iCCP_SUPPORTED
306 else if (png_ptr->chunk_name == png_iCCP)
308 PNG_PUSH_SAVE_BUFFER_IF_FULL
309 png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
313 #ifdef PNG_READ_sPLT_SUPPORTED
314 else if (chunk_name == png_sPLT)
316 PNG_PUSH_SAVE_BUFFER_IF_FULL
317 png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
321 #ifdef PNG_READ_tRNS_SUPPORTED
322 else if (chunk_name == png_tRNS)
324 PNG_PUSH_SAVE_BUFFER_IF_FULL
325 png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
329 #ifdef PNG_READ_bKGD_SUPPORTED
330 else if (chunk_name == png_bKGD)
332 PNG_PUSH_SAVE_BUFFER_IF_FULL
333 png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
337 #ifdef PNG_READ_hIST_SUPPORTED
338 else if (chunk_name == png_hIST)
340 PNG_PUSH_SAVE_BUFFER_IF_FULL
341 png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
345 #ifdef PNG_READ_pHYs_SUPPORTED
346 else if (chunk_name == png_pHYs)
348 PNG_PUSH_SAVE_BUFFER_IF_FULL
349 png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
353 #ifdef PNG_READ_oFFs_SUPPORTED
354 else if (chunk_name == png_oFFs)
356 PNG_PUSH_SAVE_BUFFER_IF_FULL
357 png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
361 #ifdef PNG_READ_pCAL_SUPPORTED
362 else if (chunk_name == png_pCAL)
364 PNG_PUSH_SAVE_BUFFER_IF_FULL
365 png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
369 #ifdef PNG_READ_sCAL_SUPPORTED
370 else if (chunk_name == png_sCAL)
372 PNG_PUSH_SAVE_BUFFER_IF_FULL
373 png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
377 #ifdef PNG_READ_tIME_SUPPORTED
378 else if (chunk_name == png_tIME)
380 PNG_PUSH_SAVE_BUFFER_IF_FULL
381 png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
385 #ifdef PNG_READ_tEXt_SUPPORTED
386 else if (chunk_name == png_tEXt)
388 PNG_PUSH_SAVE_BUFFER_IF_FULL
389 png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
393 #ifdef PNG_READ_zTXt_SUPPORTED
394 else if (chunk_name == png_zTXt)
396 PNG_PUSH_SAVE_BUFFER_IF_FULL
397 png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
401 #ifdef PNG_READ_iTXt_SUPPORTED
402 else if (chunk_name == png_iTXt)
404 PNG_PUSH_SAVE_BUFFER_IF_FULL
405 png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
411 PNG_PUSH_SAVE_BUFFER_IF_FULL
412 png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
413 PNG_HANDLE_CHUNK_AS_DEFAULT);
416 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
420 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
428 if (png_ptr->save_buffer_size != 0)
430 png_size_t save_size;
432 if (length < png_ptr->save_buffer_size)
436 save_size = png_ptr->save_buffer_size;
438 memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
441 png_ptr->buffer_size -= save_size;
442 png_ptr->save_buffer_size -= save_size;
443 png_ptr->save_buffer_ptr += save_size;
445 if (length != 0 && png_ptr->current_buffer_size != 0)
447 png_size_t save_size;
449 if (length < png_ptr->current_buffer_size)
453 save_size = png_ptr->current_buffer_size;
455 memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
456 png_ptr->buffer_size -= save_size;
457 png_ptr->current_buffer_size -= save_size;
458 png_ptr->current_buffer_ptr += save_size;
463 png_push_save_buffer(png_structrp png_ptr)
465 if (png_ptr->save_buffer_size != 0)
467 if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
473 istop = png_ptr->save_buffer_size;
474 for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
475 i < istop; i++, sp++, dp++)
481 if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
482 png_ptr->save_buffer_max)
485 png_bytep old_buffer;
487 if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
488 (png_ptr->current_buffer_size + 256))
490 png_error(png_ptr, "Potential overflow of save_buffer");
493 new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
494 old_buffer = png_ptr->save_buffer;
495 png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
496 (png_size_t)new_max);
498 if (png_ptr->save_buffer == NULL)
500 png_free(png_ptr, old_buffer);
501 png_error(png_ptr, "Insufficient memory for save_buffer");
505 memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
506 else if (png_ptr->save_buffer_size)
507 png_error(png_ptr, "save_buffer error");
508 png_free(png_ptr, old_buffer);
509 png_ptr->save_buffer_max = new_max;
511 if (png_ptr->current_buffer_size)
513 memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
514 png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
515 png_ptr->save_buffer_size += png_ptr->current_buffer_size;
516 png_ptr->current_buffer_size = 0;
518 png_ptr->save_buffer_ptr = png_ptr->save_buffer;
519 png_ptr->buffer_size = 0;
523 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
524 png_size_t buffer_length)
526 png_ptr->current_buffer = buffer;
527 png_ptr->current_buffer_size = buffer_length;
528 png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
529 png_ptr->current_buffer_ptr = png_ptr->current_buffer;
533 png_push_read_IDAT(png_structrp png_ptr)
535 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
537 png_byte chunk_length[4];
538 png_byte chunk_tag[4];
540 /* TODO: this code can be commoned up with the same code in push_read */
541 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
542 png_push_fill_buffer(png_ptr, chunk_length, 4);
543 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
544 png_reset_crc(png_ptr);
545 png_crc_read(png_ptr, chunk_tag, 4);
546 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
547 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
549 if (png_ptr->chunk_name != png_IDAT)
551 png_ptr->process_mode = PNG_READ_CHUNK_MODE;
553 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
554 png_error(png_ptr, "Not enough compressed data");
559 png_ptr->idat_size = png_ptr->push_length;
562 if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
564 png_size_t save_size = png_ptr->save_buffer_size;
565 png_uint_32 idat_size = png_ptr->idat_size;
567 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
568 * are of different types and we don't know which variable has the fewest
569 * bits. Carefully select the smaller and cast it to the type of the
570 * larger - this cannot overflow. Do not cast in the following test - it
571 * will break on either 16-bit or 64-bit platforms.
573 if (idat_size < save_size)
574 save_size = (png_size_t)idat_size;
577 idat_size = (png_uint_32)save_size;
579 png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
581 png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
583 png_ptr->idat_size -= idat_size;
584 png_ptr->buffer_size -= save_size;
585 png_ptr->save_buffer_size -= save_size;
586 png_ptr->save_buffer_ptr += save_size;
589 if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
591 png_size_t save_size = png_ptr->current_buffer_size;
592 png_uint_32 idat_size = png_ptr->idat_size;
594 /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
595 * are of different types and we don't know which variable has the fewest
596 * bits. Carefully select the smaller and cast it to the type of the
597 * larger - this cannot overflow.
599 if (idat_size < save_size)
600 save_size = (png_size_t)idat_size;
603 idat_size = (png_uint_32)save_size;
605 png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
607 png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
609 png_ptr->idat_size -= idat_size;
610 png_ptr->buffer_size -= save_size;
611 png_ptr->current_buffer_size -= save_size;
612 png_ptr->current_buffer_ptr += save_size;
615 if (png_ptr->idat_size == 0)
617 PNG_PUSH_SAVE_BUFFER_IF_LT(4)
618 png_crc_finish(png_ptr, 0);
619 png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
620 png_ptr->mode |= PNG_AFTER_IDAT;
626 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
627 png_size_t buffer_length)
629 /* The caller checks for a non-zero buffer length. */
630 if (!(buffer_length > 0) || buffer == NULL)
631 png_error(png_ptr, "No IDAT data (internal error)");
633 /* This routine must process all the data it has been given
634 * before returning, calling the row callback as required to
635 * handle the uncompressed results.
637 png_ptr->zstream.next_in = buffer;
638 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
639 png_ptr->zstream.avail_in = (uInt)buffer_length;
641 /* Keep going until the decompressed data is all processed
642 * or the stream marked as finished.
644 while (png_ptr->zstream.avail_in > 0 &&
645 (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
649 /* We have data for zlib, but we must check that zlib
650 * has someplace to put the results. It doesn't matter
651 * if we don't expect any results -- it may be the input
652 * data is just the LZ end code.
654 if (!(png_ptr->zstream.avail_out > 0))
656 /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
657 png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
658 png_ptr->iwidth) + 1);
660 png_ptr->zstream.next_out = png_ptr->row_buf;
663 /* Using Z_SYNC_FLUSH here means that an unterminated
664 * LZ stream (a stream with a missing end code) can still
665 * be handled, otherwise (Z_NO_FLUSH) a future zlib
666 * implementation might defer output and therefore
667 * change the current behavior (see comments in inflate.c
668 * for why this doesn't happen at present with zlib 1.2.5).
670 ret = PNG_INFLATE(png_ptr, Z_SYNC_FLUSH);
672 /* Check for any failure before proceeding. */
673 if (ret != Z_OK && ret != Z_STREAM_END)
675 /* Terminate the decompression. */
676 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
679 /* This may be a truncated stream (missing or
680 * damaged end code). Treat that as a warning.
682 if (png_ptr->row_number >= png_ptr->num_rows ||
684 png_warning(png_ptr, "Truncated compressed data in IDAT");
687 png_error(png_ptr, "Decompression error in IDAT");
689 /* Skip the check on unprocessed input */
693 /* Did inflate output any data? */
694 if (png_ptr->zstream.next_out != png_ptr->row_buf)
696 /* Is this unexpected data after the last row?
697 * If it is, artificially terminate the LZ output
700 if (png_ptr->row_number >= png_ptr->num_rows ||
704 png_warning(png_ptr, "Extra compressed data in IDAT");
705 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
708 /* Do no more processing; skip the unprocessed
714 /* Do we have a complete row? */
715 if (png_ptr->zstream.avail_out == 0)
716 png_push_process_row(png_ptr);
719 /* And check for the end of the stream. */
720 if (ret == Z_STREAM_END)
721 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
724 /* All the data should have been processed, if anything
725 * is left at this point we have bytes of IDAT data
726 * after the zlib end code.
728 if (png_ptr->zstream.avail_in > 0)
729 png_warning(png_ptr, "Extra compression data in IDAT");
733 png_push_process_row(png_structrp png_ptr)
735 /* 1.5.6: row_info moved out of png_struct to a local here. */
736 png_row_info row_info;
738 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
739 row_info.color_type = png_ptr->color_type;
740 row_info.bit_depth = png_ptr->bit_depth;
741 row_info.channels = png_ptr->channels;
742 row_info.pixel_depth = png_ptr->pixel_depth;
743 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
745 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
747 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
748 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
749 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
751 png_error(png_ptr, "bad adaptive filter value");
754 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
755 * 1.5.6, while the buffer really is this big in current versions of libpng
756 * it may not be in the future, so this was changed just to copy the
757 * interlaced row count:
759 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
761 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
762 if (png_ptr->transformations != 0)
763 png_do_read_transformations(png_ptr, &row_info);
766 /* The transformed pixel depth should match the depth now in row_info. */
767 if (png_ptr->transformed_pixel_depth == 0)
769 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
770 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
771 png_error(png_ptr, "progressive row overflow");
774 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
775 png_error(png_ptr, "internal progressive row size calculation error");
778 #ifdef PNG_READ_INTERLACING_SUPPORTED
779 /* Expand interlaced rows to full size */
780 if (png_ptr->interlaced != 0 &&
781 (png_ptr->transformations & PNG_INTERLACE) != 0)
783 if (png_ptr->pass < 6)
784 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
785 png_ptr->transformations);
787 switch (png_ptr->pass)
792 for (i = 0; i < 8 && png_ptr->pass == 0; i++)
794 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
795 png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
798 if (png_ptr->pass == 2) /* Pass 1 might be empty */
800 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
802 png_push_have_row(png_ptr, NULL);
803 png_read_push_finish_row(png_ptr);
807 if (png_ptr->pass == 4 && png_ptr->height <= 4)
809 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
811 png_push_have_row(png_ptr, NULL);
812 png_read_push_finish_row(png_ptr);
816 if (png_ptr->pass == 6 && png_ptr->height <= 4)
818 png_push_have_row(png_ptr, NULL);
819 png_read_push_finish_row(png_ptr);
828 for (i = 0; i < 8 && png_ptr->pass == 1; i++)
830 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
831 png_read_push_finish_row(png_ptr);
834 if (png_ptr->pass == 2) /* Skip top 4 generated rows */
836 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
838 png_push_have_row(png_ptr, NULL);
839 png_read_push_finish_row(png_ptr);
850 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
852 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
853 png_read_push_finish_row(png_ptr);
856 for (i = 0; i < 4 && png_ptr->pass == 2; i++)
858 png_push_have_row(png_ptr, NULL);
859 png_read_push_finish_row(png_ptr);
862 if (png_ptr->pass == 4) /* Pass 3 might be empty */
864 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
866 png_push_have_row(png_ptr, NULL);
867 png_read_push_finish_row(png_ptr);
878 for (i = 0; i < 4 && png_ptr->pass == 3; i++)
880 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
881 png_read_push_finish_row(png_ptr);
884 if (png_ptr->pass == 4) /* Skip top two generated rows */
886 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
888 png_push_have_row(png_ptr, NULL);
889 png_read_push_finish_row(png_ptr);
900 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
902 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
903 png_read_push_finish_row(png_ptr);
906 for (i = 0; i < 2 && png_ptr->pass == 4; i++)
908 png_push_have_row(png_ptr, NULL);
909 png_read_push_finish_row(png_ptr);
912 if (png_ptr->pass == 6) /* Pass 5 might be empty */
914 png_push_have_row(png_ptr, NULL);
915 png_read_push_finish_row(png_ptr);
925 for (i = 0; i < 2 && png_ptr->pass == 5; i++)
927 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
928 png_read_push_finish_row(png_ptr);
931 if (png_ptr->pass == 6) /* Skip top generated row */
933 png_push_have_row(png_ptr, NULL);
934 png_read_push_finish_row(png_ptr);
943 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
944 png_read_push_finish_row(png_ptr);
946 if (png_ptr->pass != 6)
949 png_push_have_row(png_ptr, NULL);
950 png_read_push_finish_row(png_ptr);
957 png_push_have_row(png_ptr, png_ptr->row_buf + 1);
958 png_read_push_finish_row(png_ptr);
963 png_read_push_finish_row(png_structrp png_ptr)
965 #ifdef PNG_READ_INTERLACING_SUPPORTED
966 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
968 /* Start of interlace block */
969 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
971 /* Offset to next interlace block */
972 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
974 /* Start of interlace block in the y direction */
975 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
977 /* Offset to next interlace block in the y direction */
978 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
980 /* Height of interlace block. This is not currently used - if you need
981 * it, uncomment it here and in png.h
982 static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
986 png_ptr->row_number++;
987 if (png_ptr->row_number < png_ptr->num_rows)
990 #ifdef PNG_READ_INTERLACING_SUPPORTED
991 if (png_ptr->interlaced != 0)
993 png_ptr->row_number = 0;
994 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
999 if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
1000 (png_ptr->pass == 3 && png_ptr->width < 3) ||
1001 (png_ptr->pass == 5 && png_ptr->width < 2))
1004 if (png_ptr->pass > 7)
1007 if (png_ptr->pass >= 7)
1010 png_ptr->iwidth = (png_ptr->width +
1011 png_pass_inc[png_ptr->pass] - 1 -
1012 png_pass_start[png_ptr->pass]) /
1013 png_pass_inc[png_ptr->pass];
1015 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
1018 png_ptr->num_rows = (png_ptr->height +
1019 png_pass_yinc[png_ptr->pass] - 1 -
1020 png_pass_ystart[png_ptr->pass]) /
1021 png_pass_yinc[png_ptr->pass];
1023 } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
1025 #endif /* READ_INTERLACING */
1029 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
1031 if (png_ptr->info_fn != NULL)
1032 (*(png_ptr->info_fn))(png_ptr, info_ptr);
1036 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
1038 if (png_ptr->end_fn != NULL)
1039 (*(png_ptr->end_fn))(png_ptr, info_ptr);
1043 png_push_have_row(png_structrp png_ptr, png_bytep row)
1045 if (png_ptr->row_fn != NULL)
1046 (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
1047 (int)png_ptr->pass);
1050 #ifdef PNG_READ_INTERLACING_SUPPORTED
1052 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
1053 png_const_bytep new_row)
1055 if (png_ptr == NULL)
1058 /* new_row is a flag here - if it is NULL then the app callback was called
1059 * from an empty row (see the calls to png_struct::row_fn below), otherwise
1060 * it must be png_ptr->row_buf+1
1062 if (new_row != NULL)
1063 png_combine_row(png_ptr, old_row, 1/*blocky display*/);
1065 #endif /* READ_INTERLACING */
1068 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
1069 png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
1070 png_progressive_end_ptr end_fn)
1072 if (png_ptr == NULL)
1075 png_ptr->info_fn = info_fn;
1076 png_ptr->row_fn = row_fn;
1077 png_ptr->end_fn = end_fn;
1079 png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
1083 png_get_progressive_ptr(png_const_structrp png_ptr)
1085 if (png_ptr == NULL)
1088 return png_ptr->io_ptr;
1090 #endif /* PROGRESSIVE_READ */