PeerStreamer

/*

 * Concat URL protocol

 * Copyright (c) 2006 Steve Lhomme

 * Copyright (c) 2007 Wolfram Gloger

 * Copyright (c) 2010 Michele Orrù

 *

 * 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

 */

#include "avformat.h"

#include "libavutil/avstring.h"

#include "libavutil/mem.h"

#include "url.h"

#define AV_CAT_SEPARATOR "|"

struct concat_nodes {

    URLContext *uc;                ///< node's URLContext

    int64_t     size;              ///< url filesize

};

struct concat_data {

    struct concat_nodes *nodes;    ///< list of nodes to concat

    size_t               length;   ///< number of cat'ed nodes

    size_t               current;  ///< index of currently read node

};

static av_cold int concat_close(URLContext *h)

{

    int err = 0;

    size_t i;

    struct concat_data  *data  = h->priv_data;

    struct concat_nodes *nodes = data->nodes;

    for (i = 0; i != data->length; i++)

        err |= url_close(nodes[i].uc);

    av_freep(&data->nodes);

    av_freep(&h->priv_data);

    return err < 0 ? -1 : 0;

}

static av_cold int concat_open(URLContext *h, const char *uri, int flags)

{

    char *node_uri = NULL, *tmp_uri;

    int err = 0;

    int64_t size;

    size_t  len, i;

    URLContext *uc;

    struct concat_data  *data;

    struct concat_nodes *nodes;

    av_strstart(uri, "concat:", &uri);

    /* creating data */

    if (!(data = av_mallocz(sizeof(*data))))

        return AVERROR(ENOMEM);

    h->priv_data = data;

    for (i = 0, len = 1; uri[i]; i++)

        if (uri[i] == *AV_CAT_SEPARATOR)

            /* integer overflow */

            if (++len == UINT_MAX / sizeof(*nodes)) {

                av_freep(&h->priv_data);

                return AVERROR(ENAMETOOLONG);

            }

    if (!(nodes = av_malloc(sizeof(*nodes) * len))) {

        av_freep(&h->priv_data);

        return AVERROR(ENOMEM);

    } else

        data->nodes = nodes;

    /* handle input */

    if (!*uri)

        err = AVERROR(ENOENT);

    for (i = 0; *uri; i++) {

        /* parsing uri */

        len = strcspn(uri, AV_CAT_SEPARATOR);

        if (!(tmp_uri = av_realloc(node_uri, len+1))) {

            err = AVERROR(ENOMEM);

            break;

        } else

            node_uri = tmp_uri;

        av_strlcpy(node_uri, uri, len+1);

        uri += len + strspn(uri+len, AV_CAT_SEPARATOR);

        /* creating URLContext */

        if ((err = ffurl_open(&uc, node_uri, flags)) < 0)

            break;

        /* creating size */

        if ((size = url_filesize(uc)) < 0) {

            url_close(uc);

            err = AVERROR(ENOSYS);

            break;

        }

        /* assembling */

        nodes[i].uc   = uc;

        nodes[i].size = size;

    }

    av_free(node_uri);

    data->length = i;

    if (err < 0)

        concat_close(h);

    else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {

        concat_close(h);

        err = AVERROR(ENOMEM);

    } else

        data->nodes = nodes;

    return err;

}

static int concat_read(URLContext *h, unsigned char *buf, int size)

{

    int result, total = 0;

    struct concat_data  *data  = h->priv_data;

    struct concat_nodes *nodes = data->nodes;

    size_t i = data->current;

    while (size > 0) {

        result = ffurl_read(nodes[i].uc, buf, size);

        if (result < 0)

            return total ? total : result;

        if (!result)

            if (i + 1 == data->length ||

                url_seek(nodes[++i].uc, 0, SEEK_SET) < 0)

                break;

        total += result;

        buf   += result;

        size  -= result;

    }

    data->current = i;

    return total;

}

static int64_t concat_seek(URLContext *h, int64_t pos, int whence)

{

    int64_t result;

    struct concat_data  *data  = h->priv_data;

    struct concat_nodes *nodes = data->nodes;

    size_t i;

    switch (whence) {

    case SEEK_END:

        for (i = data->length - 1;

             i && pos < -nodes[i].size;

             i--)

            pos += nodes[i].size;

        break;

    case SEEK_CUR:

        /* get the absolute position */

        for (i = 0; i != data->current; i++)

            pos += nodes[i].size;

        pos += url_seek(nodes[i].uc, 0, SEEK_CUR);

        whence = SEEK_SET;

        /* fall through with the absolute position */

    case SEEK_SET:

        for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)

            pos -= nodes[i].size;

        break;

    default:

        return AVERROR(EINVAL);

    }

    result = url_seek(nodes[i].uc, pos, whence);

    if (result >= 0) {

        data->current = i;

        while (i)

            result += nodes[--i].size;

    }

    return result;

}

URLProtocol ff_concat_protocol = {

    "concat",

    concat_open,

    concat_read,

    NULL,

    concat_seek,

    concat_close,

};