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
30typedef struct PNGParseContext {
31    ParseContext pc;
32    uint32_t chunk_pos;           ///< position inside current chunk
33    uint32_t chunk_length;        ///< length of the current chunk
34    uint32_t remaining_size;      ///< remaining size of the current chunk
35} PNGParseContext;
36
37static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
38                     const uint8_t **poutbuf, int *poutbuf_size,
39                     const uint8_t *buf, int buf_size)
40{
41    PNGParseContext *ppc = s->priv_data;
42    int next = END_NOT_FOUND;
43    int i = 0;
44
45    s->pict_type = AV_PICTURE_TYPE_NONE;
46
47    *poutbuf_size = 0;
48    if (buf_size == 0)
49        return 0;
50
51    if (!ppc->pc.frame_start_found) {
52        uint64_t state64 = ppc->pc.state64;
53        for (; i < buf_size; i++) {
54            state64 = (state64 << 8) | buf[i];
55            if (state64 == PNGSIG || state64 == MNGSIG) {
56                i++;
57                ppc->pc.frame_start_found = 1;
58                break;
59            }
60        }
61        ppc->pc.state64 = state64;
62    } else if (ppc->remaining_size) {
63        i = FFMIN(ppc->remaining_size, buf_size);
64        ppc->remaining_size -= i;
65        if (ppc->remaining_size)
66            goto flush;
67        if (ppc->chunk_pos == -1) {
68            next = i;
69            goto flush;
70        }
71    }
72
73    for (; ppc->pc.frame_start_found && i < buf_size; i++) {
74        ppc->pc.state = (ppc->pc.state << 8) | buf[i];
75        if (ppc->chunk_pos == 3) {
76            ppc->chunk_length = ppc->pc.state;
77            if (ppc->chunk_length > 0x7fffffff) {
78                ppc->chunk_pos = ppc->pc.frame_start_found = 0;
79                goto flush;
80            }
81            ppc->chunk_length += 4;
82        } else if (ppc->chunk_pos == 7) {
83            if (ppc->chunk_length >= buf_size - i)
84                ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
85            if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
86                if (ppc->remaining_size)
87                    ppc->chunk_pos = -1;
88                else
89                    next = ppc->chunk_length + i + 1;
90                break;
91            } else {
92                ppc->chunk_pos = 0;
93                if (ppc->remaining_size)
94                    break;
95                else
96                    i += ppc->chunk_length;
97                continue;
98            }
99        }
100        ppc->chunk_pos++;
101    }
102
103flush:
104    if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
105        return buf_size;
106
107    ppc->chunk_pos = ppc->pc.frame_start_found = 0;
108
109    *poutbuf      = buf;
110    *poutbuf_size = buf_size;
111    return next;
112}
113
114AVCodecParser ff_png_parser = {
115    .codec_ids      = { AV_CODEC_ID_PNG },
116    .priv_data_size = sizeof(PNGParseContext),
117    .parser_parse   = png_parse,
118    .parser_close   = ff_parse_close,
119};
120