/*

 * WebP parser

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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.

 *

 * FFmpeg 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 FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * WebP parser

 */

#include "libavutil/bswap.h"

#include "libavutil/common.h"

#include "parser.h"

typedef struct WebPParseContext {

    ParseContext pc;

    uint32_t fsize;

    uint32_t remaining_size;

} WebPParseContext;

static int webp_parse(AVCodecParserContext *s, AVCodecContext *avctx,

                      const uint8_t **poutbuf, int *poutbuf_size,

                      const uint8_t *buf, int buf_size)

{

    WebPParseContext *ctx = s->priv_data;

    uint64_t state = ctx->pc.state64;

    int next = END_NOT_FOUND;

    int i = 0;

    *poutbuf      = NULL;

    *poutbuf_size = 0;

restart:

    if (ctx->pc.frame_start_found <= 8) {

        for (; i < buf_size; i++) {

            state = (state << 8) | buf[i];

            if (ctx->pc.frame_start_found == 0) {

                if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {

                    ctx->fsize = av_bswap32(state);

                    if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {

                        ctx->pc.frame_start_found = 1;

                        ctx->fsize += 8;

                    }

                }

            } else if (ctx->pc.frame_start_found == 8) {

                if ((state >> 32) != MKBETAG('W', 'E', 'B', 'P')) {

                    ctx->pc.frame_start_found = 0;

                    continue;

                }

                ctx->pc.frame_start_found++;

                ctx->remaining_size = ctx->fsize + i - 15;

                if (ctx->pc.index + i > 15) {

                    next = i - 15;

                    state = 0;

                    break;

                } else {

                    ctx->pc.state64 = 0;

                    goto restart;

                }

            } else if (ctx->pc.frame_start_found)

                ctx->pc.frame_start_found++;

        }

        ctx->pc.state64 = state;

    } else {

        if (ctx->remaining_size) {

            i = FFMIN(ctx->remaining_size, buf_size);

            ctx->remaining_size -= i;

            if (ctx->remaining_size)

                goto flush;

            ctx->pc.frame_start_found = 0;

            goto restart;

        }

    }

flush:

    if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0)

        return buf_size;

    if (next != END_NOT_FOUND && next < 0)

        ctx->pc.frame_start_found = FFMAX(ctx->pc.frame_start_found - i - 1, 0);

    else

        ctx->pc.frame_start_found = 0;

    *poutbuf      = buf;

    *poutbuf_size = buf_size;

    return next;

}

const AVCodecParser ff_webp_parser = {

    .codec_ids      = { AV_CODEC_ID_WEBP },

    .priv_data_size = sizeof(WebPParseContext),

    .parser_parse   = webp_parse,

    .parser_close   = ff_parse_close,

};