ffmpeg/libavformat/concat.c

   1 /*
   2  * Concat URL protocol
   3  * Copyright (c) 2006 Steve Lhomme
   4  * Copyright (c) 2007 Wolfram Gloger
   5  * Copyright (c) 2010 Michele Orrù
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include "libavutil/avstring.h"
  25 #include "libavutil/mem.h"
  26
  27 #include "avformat.h"
  28 #include "url.h"
  29
  30 #define AV_CAT_SEPARATOR "|"
  31
  32 struct concat_nodes {
  33     URLContext *uc;                ///< node's URLContext
  34     int64_t     size;              ///< url filesize
  35 };
  36
  37 struct concat_data {
  38     struct concat_nodes *nodes;    ///< list of nodes to concat
  39     size_t               length;   ///< number of cat'ed nodes
  40     size_t               current;  ///< index of currently read node
  41 };
  42
  43 static av_cold int concat_close(URLContext *h)
  44 {
  45     int err = 0;
  46     size_t i;
  47     struct concat_data  *data  = h->priv_data;
  48     struct concat_nodes *nodes = data->nodes;
  49
  50     for (i = 0; i != data->length; i++)
  51         err |= ffurl_close(nodes[i].uc);
  52
  53     av_freep(&data->nodes);
  54
  55     return err < 0 ? -1 : 0;
  56 }
  57
  58 static av_cold int concat_open(URLContext *h, const char *uri, int flags)
  59 {
  60     char *node_uri = NULL;
  61     int err = 0;
  62     int64_t size;
  63     size_t len, i;
  64     URLContext *uc;
  65     struct concat_data  *data = h->priv_data;
  66     struct concat_nodes *nodes;
  67
  68     av_strstart(uri, "concat:", &uri);
  69
  70     for (i = 0, len = 1; uri[i]; i++) {
  71         if (uri[i] == *AV_CAT_SEPARATOR) {
  72             /* integer overflow */
  73             if (++len == UINT_MAX / sizeof(*nodes)) {
  74                 av_freep(&h->priv_data);
  75                 return AVERROR(ENAMETOOLONG);
  76             }
  77         }
  78     }
  79
  80     if (!(nodes = av_realloc(NULL, sizeof(*nodes) * len)))
  81         return AVERROR(ENOMEM);
  82     else
  83         data->nodes = nodes;
  84
  85     /* handle input */
  86     if (!*uri)
  87         err = AVERROR(ENOENT);
  88     for (i = 0; *uri; i++) {
  89         /* parsing uri */
  90         len = strcspn(uri, AV_CAT_SEPARATOR);
  91         if ((err = av_reallocp(&node_uri, len + 1)) < 0)
  92             break;
  93         av_strlcpy(node_uri, uri, len + 1);
  94         uri += len + strspn(uri + len, AV_CAT_SEPARATOR);
  95
  96         /* creating URLContext */
  97         if ((err = ffurl_open(&uc, node_uri, flags,
  98                               &h->interrupt_callback, NULL)) < 0)
  99             break;
 100
 101         /* creating size */
 102         if ((size = ffurl_size(uc)) < 0) {
 103             ffurl_close(uc);
 104             err = AVERROR(ENOSYS);
 105             break;
 106         }
 107
 108         /* assembling */
 109         nodes[i].uc   = uc;
 110         nodes[i].size = size;
 111     }
 112     av_free(node_uri);
 113     data->length = i;
 114
 115     if (err < 0)
 116         concat_close(h);
 117     else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
 118         concat_close(h);
 119         err = AVERROR(ENOMEM);
 120     } else
 121         data->nodes = nodes;
 122     return err;
 123 }
 124
 125 static int concat_read(URLContext *h, unsigned char *buf, int size)
 126 {
 127     int result, total = 0;
 128     struct concat_data  *data  = h->priv_data;
 129     struct concat_nodes *nodes = data->nodes;
 130     size_t i                   = data->current;
 131
 132     while (size > 0) {
 133         result = ffurl_read(nodes[i].uc, buf, size);
 134         if (result < 0)
 135             return total ? total : result;
 136         if (!result) {
 137             if (i + 1 == data->length ||
 138                 ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
 139                 break;
 140         }
 141         total += result;
 142         buf   += result;
 143         size  -= result;
 144     }
 145     data->current = i;
 146     return total;
 147 }
 148
 149 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
 150 {
 151     int64_t result;
 152     struct concat_data  *data  = h->priv_data;
 153     struct concat_nodes *nodes = data->nodes;
 154     size_t i;
 155
 156     switch (whence) {
 157     case SEEK_END:
 158         for (i = data->length - 1; i && pos < -nodes[i].size; i--)
 159             pos += nodes[i].size;
 160         break;
 161     case SEEK_CUR:
 162         /* get the absolute position */
 163         for (i = 0; i != data->current; i++)
 164             pos += nodes[i].size;
 165         pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
 166         whence = SEEK_SET;
 167         /* fall through with the absolute position */
 168     case SEEK_SET:
 169         for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
 170             pos -= nodes[i].size;
 171         break;
 172     default:
 173         return AVERROR(EINVAL);
 174     }
 175
 176     result = ffurl_seek(nodes[i].uc, pos, whence);
 177     if (result >= 0) {
 178         data->current = i;
 179         while (i)
 180             result += nodes[--i].size;
 181     }
 182     return result;
 183 }
 184
 185 URLProtocol ff_concat_protocol = {
 186     .name           = "concat",
 187     .url_open       = concat_open,
 188     .url_read       = concat_read,
 189     .url_seek       = concat_seek,
 190     .url_close      = concat_close,
 191     .priv_data_size = sizeof(struct concat_data),
 192 };