xiph.c

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/*
 * Copyright (C) 2007 The FFmpeg Project
 *
 * 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
 */
 
#include "libavutil/intreadwrite.h"
#include "xiph.h"
 
int avpriv_split_xiph_headers(const uint8_t *extradata, int extradata_size,
                          int first_header_size, const uint8_t *header_start[3],
                          int header_len[3])
{
    int i;
 
    if (extradata_size >= 6 && AV_RB16(extradata) == first_header_size) {
        int overall_len = 6;
        for (i=0; i<3; i++) {
            header_len[i] = AV_RB16(extradata);
            extradata += 2;
            header_start[i] = extradata;
            extradata += header_len[i];
            if (overall_len > extradata_size - header_len[i])
                return AVERROR_INVALIDDATA;
            overall_len += header_len[i];
        }
    } else if (extradata_size >= 3 && extradata_size < INT_MAX - 0x1ff && extradata[0] == 2) {
        int overall_len = 3;
        extradata++;
        for (i=0; i<2; i++, extradata++) {
            header_len[i] = 0;
            for (; overall_len < extradata_size && *extradata==0xff; extradata++) {
                header_len[i] += 0xff;
                overall_len   += 0xff + 1;
            }
            header_len[i] += *extradata;
            overall_len   += *extradata;
            if (overall_len > extradata_size)
                return AVERROR_INVALIDDATA;
        }
        header_len[2] = extradata_size - overall_len;
        header_start[0] = extradata;
        header_start[1] = header_start[0] + header_len[0];
        header_start[2] = header_start[1] + header_len[1];
    } else {
        return -1;
    }
    return 0;
}