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png_parser.c
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1 /*
2  * PNG parser
3  * Copyright (c) 2009 Peter Holik
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * PNG parser
25  */
26 
27 #include "parser.h"
28 #include "png.h"
29 
30 typedef struct PNGParseContext
31 {
33  uint32_t index;
34  uint32_t chunk_length;
35  uint32_t remaining_size;
37 
39  const uint8_t **poutbuf, int *poutbuf_size,
40  const uint8_t *buf, int buf_size)
41 {
42  PNGParseContext *ppc = s->priv_data;
43  int next = END_NOT_FOUND;
44  int i = 0;
45 
47 
48  *poutbuf_size = 0;
49  if (buf_size == 0)
50  return 0;
51 
52  if (!ppc->pc.frame_start_found) {
53  uint64_t state64 = ppc->pc.state64;
54  for (; i < buf_size; i++) {
55  state64 = (state64 << 8) | buf[i];
56  if (state64 == PNGSIG || state64 == MNGSIG) {
57  i++;
58  ppc->pc.frame_start_found = 1;
59  break;
60  }
61  }
62  ppc->pc.state64 = state64;
63  } else
64  if (ppc->remaining_size) {
65  i = FFMIN(ppc->remaining_size, buf_size);
66  ppc->remaining_size -= i;
67  if (ppc->remaining_size)
68  goto flush;
69  if (ppc->index == -1) {
70  next = i;
71  goto flush;
72  }
73  }
74 
75  for (;ppc->pc.frame_start_found && i < buf_size; i++) {
76  ppc->pc.state = (ppc->pc.state<<8) | buf[i];
77  if (ppc->index == 3) {
78  ppc->chunk_length = ppc->pc.state;
79  if (ppc->chunk_length > 0x7fffffff) {
80  ppc->index = ppc->pc.frame_start_found = 0;
81  goto flush;
82  }
83  ppc->chunk_length += 4;
84  } else if (ppc->index == 7) {
85  if (ppc->chunk_length >= buf_size - i)
86  ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
87  if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
88  if (ppc->remaining_size)
89  ppc->index = -1;
90  else
91  next = ppc->chunk_length + i + 1;
92  break;
93  } else {
94  ppc->index = 0;
95  if (ppc->remaining_size)
96  break;
97  else
98  i += ppc->chunk_length;
99  continue;
100  }
101  }
102  ppc->index++;
103  }
104 flush:
105  if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
106  return buf_size;
107 
108  ppc->index = ppc->pc.frame_start_found = 0;
109 
110  *poutbuf = buf;
111  *poutbuf_size = buf_size;
112  return next;
113 }
114 
116  .codec_ids = { AV_CODEC_ID_PNG },
117  .priv_data_size = sizeof(PNGParseContext),
118  .parser_parse = png_parse,
119  .parser_close = ff_parse_close,
120 };