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/*
* PNG parser
* Copyright (c) 2009 Peter Holik
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* PNG parser
*/
#include "libavutil/intreadwrite.h"
#include "libavutil/common.h"
#include "parser.h"
#define PNG_SIGNATURE UINT64_C(0x89504e470d0a1a0a)
#define MNG_SIGNATURE UINT64_C(0x8a4d4e470d0a1a0a)
typedef struct PNGParseContext {
ParseContext pc;
int chunk_pos; ///< position inside current chunk
int chunk_length; ///< length of the current chunk
int remaining_size; ///< remaining size of the current chunk
} PNGParseContext;
static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
PNGParseContext *ppc = s->priv_data;
int next = END_NOT_FOUND;
int i = 0;
*poutbuf_size = 0;
if (buf_size == 0)
return 0;
if (!ppc->pc.frame_start_found) {
uint64_t state64 = ppc->pc.state64;
for (; i < buf_size; i++) {
state64 = (state64 << 8) | buf[i];
if (state64 == PNG_SIGNATURE ||
state64 == MNG_SIGNATURE) {
i++;
ppc->pc.frame_start_found = 1;
break;
}
}
ppc->pc.state64 = state64;
} else if (ppc->remaining_size) {
i = FFMIN(ppc->remaining_size, buf_size);
ppc->remaining_size -= i;
if (ppc->remaining_size)
goto flush;
if (ppc->chunk_pos == -1) {
next = i;
goto flush;
}
}
for (; ppc->pc.frame_start_found && i < buf_size; i++) {
ppc->pc.state = (ppc->pc.state << 8) | buf[i];
if (ppc->chunk_pos == 3) {
ppc->chunk_length = AV_RL32(&ppc->pc.state);
if (ppc->chunk_length > 0x7fffffff) {
ppc->chunk_pos = ppc->pc.frame_start_found = 0;
goto flush;
}
ppc->chunk_length += 4;
} else if (ppc->chunk_pos == 7) {
if (ppc->chunk_length >= buf_size - i)
ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
if (AV_RB32(&ppc->pc.state) == MKTAG('I', 'E', 'N', 'D')) {
if (ppc->remaining_size)
ppc->chunk_pos = -1;
else
next = ppc->chunk_length + i + 1;
break;
} else {
ppc->chunk_pos = 0;
if (ppc->remaining_size)
break;
else
i += ppc->chunk_length;
continue;
}
}
ppc->chunk_pos++;
}
flush:
if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
return buf_size;
ppc->chunk_pos = ppc->pc.frame_start_found = 0;
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
AVCodecParser ff_png_parser = {
.codec_ids = { AV_CODEC_ID_PNG },
.priv_data_size = sizeof(PNGParseContext),
.parser_parse = png_parse,
.parser_close = ff_parse_close,
};
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