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libavformat/concat.c

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00001 /*
00002  * Concat URL protocol
00003  * Copyright (c) 2006 Steve Lhomme
00004  * Copyright (c) 2007 Wolfram Gloger
00005  * Copyright (c) 2010 Michele OrrĂ¹
00006  *
00007  * This file is part of FFmpeg.
00008  *
00009  * FFmpeg is free software; you can redistribute it and/or
00010  * modify it under the terms of the GNU Lesser General Public
00011  * License as published by the Free Software Foundation; either
00012  * version 2.1 of the License, or (at your option) any later version.
00013  *
00014  * FFmpeg is distributed in the hope that it will be useful,
00015  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00016  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017  * Lesser General Public License for more details.
00018  *
00019  * You should have received a copy of the GNU Lesser General Public
00020  * License along with FFmpeg; if not, write to the Free Software
00021  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00022  */
00023 
00024 #include "avformat.h"
00025 #include "libavutil/avstring.h"
00026 #include "libavutil/mem.h"
00027 #include "url.h"
00028 
00029 #define AV_CAT_SEPARATOR "|"
00030 
00031 struct concat_nodes {
00032     URLContext *uc;                
00033     int64_t     size;              
00034 };
00035 
00036 struct concat_data {
00037     struct concat_nodes *nodes;    
00038     size_t               length;   
00039     size_t               current;  
00040 };
00041 
00042 static av_cold int concat_close(URLContext *h)
00043 {
00044     int err = 0;
00045     size_t i;
00046     struct concat_data  *data  = h->priv_data;
00047     struct concat_nodes *nodes = data->nodes;
00048 
00049     for (i = 0; i != data->length; i++)
00050         err |= ffurl_close(nodes[i].uc);
00051 
00052     av_freep(&data->nodes);
00053     av_freep(&h->priv_data);
00054 
00055     return err < 0 ? -1 : 0;
00056 }
00057 
00058 static av_cold int concat_open(URLContext *h, const char *uri, int flags)
00059 {
00060     char *node_uri = NULL, *tmp_uri;
00061     int err = 0;
00062     int64_t size;
00063     size_t  len, i;
00064     URLContext *uc;
00065     struct concat_data  *data;
00066     struct concat_nodes *nodes;
00067 
00068     av_strstart(uri, "concat:", &uri);
00069 
00070     /* creating data */
00071     if (!(data = av_mallocz(sizeof(*data))))
00072         return AVERROR(ENOMEM);
00073     h->priv_data = data;
00074 
00075     for (i = 0, len = 1; uri[i]; i++)
00076         if (uri[i] == *AV_CAT_SEPARATOR)
00077             /* integer overflow */
00078             if (++len == UINT_MAX / sizeof(*nodes)) {
00079                 av_freep(&h->priv_data);
00080                 return AVERROR(ENAMETOOLONG);
00081             }
00082 
00083     if (!(nodes = av_malloc(sizeof(*nodes) * len))) {
00084         av_freep(&h->priv_data);
00085         return AVERROR(ENOMEM);
00086     } else
00087         data->nodes = nodes;
00088 
00089     /* handle input */
00090     if (!*uri)
00091         err = AVERROR(ENOENT);
00092     for (i = 0; *uri; i++) {
00093         /* parsing uri */
00094         len = strcspn(uri, AV_CAT_SEPARATOR);
00095         if (!(tmp_uri = av_realloc(node_uri, len+1))) {
00096             err = AVERROR(ENOMEM);
00097             break;
00098         } else
00099             node_uri = tmp_uri;
00100         av_strlcpy(node_uri, uri, len+1);
00101         uri += len + strspn(uri+len, AV_CAT_SEPARATOR);
00102 
00103         /* creating URLContext */
00104         if ((err = ffurl_open(&uc, node_uri, flags)) < 0)
00105             break;
00106 
00107         /* creating size */
00108         if ((size = ffurl_size(uc)) < 0) {
00109             ffurl_close(uc);
00110             err = AVERROR(ENOSYS);
00111             break;
00112         }
00113 
00114         /* assembling */
00115         nodes[i].uc   = uc;
00116         nodes[i].size = size;
00117     }
00118     av_free(node_uri);
00119     data->length = i;
00120 
00121     if (err < 0)
00122         concat_close(h);
00123     else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
00124         concat_close(h);
00125         err = AVERROR(ENOMEM);
00126     } else
00127         data->nodes = nodes;
00128     return err;
00129 }
00130 
00131 static int concat_read(URLContext *h, unsigned char *buf, int size)
00132 {
00133     int result, total = 0;
00134     struct concat_data  *data  = h->priv_data;
00135     struct concat_nodes *nodes = data->nodes;
00136     size_t i = data->current;
00137 
00138     while (size > 0) {
00139         result = ffurl_read(nodes[i].uc, buf, size);
00140         if (result < 0)
00141             return total ? total : result;
00142         if (!result)
00143             if (i + 1 == data->length ||
00144                 ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
00145                 break;
00146         total += result;
00147         buf   += result;
00148         size  -= result;
00149     }
00150     data->current = i;
00151     return total;
00152 }
00153 
00154 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
00155 {
00156     int64_t result;
00157     struct concat_data  *data  = h->priv_data;
00158     struct concat_nodes *nodes = data->nodes;
00159     size_t i;
00160 
00161     switch (whence) {
00162     case SEEK_END:
00163         for (i = data->length - 1;
00164              i && pos < -nodes[i].size;
00165              i--)
00166             pos += nodes[i].size;
00167         break;
00168     case SEEK_CUR:
00169         /* get the absolute position */
00170         for (i = 0; i != data->current; i++)
00171             pos += nodes[i].size;
00172         pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
00173         whence = SEEK_SET;
00174         /* fall through with the absolute position */
00175     case SEEK_SET:
00176         for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
00177             pos -= nodes[i].size;
00178         break;
00179     default:
00180         return AVERROR(EINVAL);
00181     }
00182 
00183     result = ffurl_seek(nodes[i].uc, pos, whence);
00184     if (result >= 0) {
00185         data->current = i;
00186         while (i)
00187             result += nodes[--i].size;
00188     }
00189     return result;
00190 }
00191 
00192 URLProtocol ff_concat_protocol = {
00193     .name      = "concat",
00194     .url_open  = concat_open,
00195     .url_read  = concat_read,
00196     .url_seek  = concat_seek,
00197     .url_close = concat_close,
00198 };

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