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    *poutbuf = NULL;
49
50    if (!ppc->pc.frame_start_found) {
51        uint64_t state64 = ppc->pc.state64;
52        for (; i < buf_size; i++) {
53            state64 = (state64 << 8) | buf[i];
54            if (state64 == PNGSIG || state64 == MNGSIG) {
55                i++;
56                ppc->pc.frame_start_found = 1;
57                break;
58            }
59        }
60        ppc->pc.state64 = state64;
61    } else if (ppc->remaining_size) {
62        i = FFMIN(ppc->remaining_size, buf_size);
63        ppc->remaining_size -= i;
64        if (ppc->remaining_size)
65            goto flush;
66        if (ppc->chunk_pos == -1) {
67            next = i;
68            goto flush;
69        }
70    }
71
72    for (; ppc->pc.frame_start_found && i < buf_size; i++) {
73        ppc->pc.state = (ppc->pc.state << 8) | buf[i];
74        if (ppc->chunk_pos == 3) {
75            ppc->chunk_length = ppc->pc.state;
76            if (ppc->chunk_length > 0x7fffffff) {
77                ppc->chunk_pos = ppc->pc.frame_start_found = 0;
78                goto flush;
79            }
80            ppc->chunk_length += 4;
81        } else if (ppc->chunk_pos == 7) {
82            if (ppc->chunk_length >= buf_size - i)
83                ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
84            if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
85                if (ppc->remaining_size)
86                    ppc->chunk_pos = -1;
87                else
88                    next = ppc->chunk_length + i + 1;
89                break;
90            } else {
91                ppc->chunk_pos = 0;
92                if (ppc->remaining_size)
93                    break;
94                else
95                    i += ppc->chunk_length;
96                continue;
97            }
98        }
99        ppc->chunk_pos++;
100    }
101
102flush:
103    if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
104        return buf_size;
105
106    ppc->chunk_pos = ppc->pc.frame_start_found = 0;
107
108    *poutbuf      = buf;
109    *poutbuf_size = buf_size;
110    return next;
111}
112
113const AVCodecParser ff_png_parser = {
114    .codec_ids      = { AV_CODEC_ID_PNG },
115    .priv_data_size = sizeof(PNGParseContext),
116    .parser_parse   = png_parse,
117    .parser_close   = ff_parse_close,
118};
119