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ffmpeg / libavformat / concat.c @ 2912e87a

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/*
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 * Concat URL protocol
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 * Copyright (c) 2006 Steve Lhomme
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 * Copyright (c) 2007 Wolfram Gloger
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 * Copyright (c) 2010 Michele OrrĂ¹
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "avformat.h"
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#include "libavutil/avstring.h"
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#include "libavutil/mem.h"
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#define AV_CAT_SEPARATOR "|"
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struct concat_nodes {
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    URLContext *uc;                ///< node's URLContext
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    int64_t     size;              ///< url filesize
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};
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struct concat_data {
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    struct concat_nodes *nodes;    ///< list of nodes to concat
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    size_t               length;   ///< number of cat'ed nodes
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    size_t               current;  ///< index of currently read node
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};
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static av_cold int concat_close(URLContext *h)
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{
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    int err = 0;
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    size_t i;
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    struct concat_data  *data  = h->priv_data;
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    struct concat_nodes *nodes = data->nodes;
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    for (i = 0; i != data->length; i++)
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        err |= url_close(nodes[i].uc);
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    av_freep(&data->nodes);
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    av_freep(&h->priv_data);
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    return err < 0 ? -1 : 0;
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}
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static av_cold int concat_open(URLContext *h, const char *uri, int flags)
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{
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    char *node_uri = NULL, *tmp_uri;
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    int err = 0;
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    int64_t size;
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    size_t  len, i;
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    URLContext *uc;
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    struct concat_data  *data;
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    struct concat_nodes *nodes;
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    av_strstart(uri, "concat:", &uri);
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    /* creating data */
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    if (!(data = av_mallocz(sizeof(*data))))
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        return AVERROR(ENOMEM);
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    h->priv_data = data;
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    for (i = 0, len = 1; uri[i]; i++)
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        if (uri[i] == *AV_CAT_SEPARATOR)
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            /* integer overflow */
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            if (++len == UINT_MAX / sizeof(*nodes)) {
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                av_freep(&h->priv_data);
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                return AVERROR(ENAMETOOLONG);
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            }
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    if (!(nodes = av_malloc(sizeof(*nodes) * len))) {
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        av_freep(&h->priv_data);
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        return AVERROR(ENOMEM);
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    } else
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        data->nodes = nodes;
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    /* handle input */
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    if (!*uri)
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        err = AVERROR(ENOENT);
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    for (i = 0; *uri; i++) {
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        /* parsing uri */
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        len = strcspn(uri, AV_CAT_SEPARATOR);
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        if (!(tmp_uri = av_realloc(node_uri, len+1))) {
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            err = AVERROR(ENOMEM);
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            break;
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        } else
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            node_uri = tmp_uri;
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        av_strlcpy(node_uri, uri, len+1);
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        uri += len + strspn(uri+len, AV_CAT_SEPARATOR);
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        /* creating URLContext */
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        if ((err = url_open(&uc, node_uri, flags)) < 0)
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            break;
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        /* creating size */
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        if ((size = url_filesize(uc)) < 0) {
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            url_close(uc);
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            err = AVERROR(ENOSYS);
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            break;
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        }
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        /* assembling */
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        nodes[i].uc   = uc;
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        nodes[i].size = size;
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    }
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    av_free(node_uri);
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    data->length = i;
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    if (err < 0)
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        concat_close(h);
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    else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
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        concat_close(h);
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        err = AVERROR(ENOMEM);
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    } else
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        data->nodes = nodes;
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    return err;
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}
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static int concat_read(URLContext *h, unsigned char *buf, int size)
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{
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    int result, total = 0;
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    struct concat_data  *data  = h->priv_data;
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    struct concat_nodes *nodes = data->nodes;
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    size_t i = data->current;
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    while (size > 0) {
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        result = url_read(nodes[i].uc, buf, size);
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        if (result < 0)
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            return total ? total : result;
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        if (!result)
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            if (i + 1 == data->length ||
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                url_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
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                break;
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        total += result;
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        buf   += result;
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        size  -= result;
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    }
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    data->current = i;
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    return total;
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}
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static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
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{
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    int64_t result;
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    struct concat_data  *data  = h->priv_data;
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    struct concat_nodes *nodes = data->nodes;
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    size_t i;
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    switch (whence) {
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    case SEEK_END:
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        for (i = data->length - 1;
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             i && pos < -nodes[i].size;
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             i--)
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            pos += nodes[i].size;
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        break;
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    case SEEK_CUR:
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        /* get the absolute position */
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        for (i = 0; i != data->current; i++)
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            pos += nodes[i].size;
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        pos += url_seek(nodes[i].uc, 0, SEEK_CUR);
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        whence = SEEK_SET;
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        /* fall through with the absolute position */
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    case SEEK_SET:
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        for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
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            pos -= nodes[i].size;
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        break;
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    default:
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        return AVERROR(EINVAL);
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    }
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    result = url_seek(nodes[i].uc, pos, whence);
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    if (result >= 0) {
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        data->current = i;
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        while (i)
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            result += nodes[--i].size;
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    }
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    return result;
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}
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URLProtocol ff_concat_protocol = {
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    "concat",
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    concat_open,
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    concat_read,
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    NULL,
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    concat_seek,
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    concat_close,
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};