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 Libav.
   8  *
   9  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include "avformat.h"
  25 #include "libavutil/avstring.h"
  26 #include "libavutil/mem.h"
  27 #include "url.h"
  28
  29 #define AV_CAT_SEPARATOR "|"
  30
  31 struct concat_nodes {
  32     URLContext *uc;                ///< node's URLContext
  33     int64_t     size;              ///< url filesize
  34 };
  35
  36 struct concat_data {
  37     struct concat_nodes *nodes;    ///< list of nodes to concat
  38     size_t               length;   ///< number of cat'ed nodes
  39     size_t               current;  ///< index of currently read node
  40 };
  41
  42 static av_cold int concat_close(URLContext *h)
  43 {
  44     int err = 0;
  45     size_t i;
  46     struct concat_data  *data  = h->priv_data;
  47     struct concat_nodes *nodes = data->nodes;
  48
  49     for (i = 0; i != data->length; i++)
  50         err |= ffurl_close(nodes[i].uc);
  51
  52     av_freep(&data->nodes);
  53
  54     return err < 0 ? -1 : 0;
  55 }
  56
  57 static av_cold int concat_open(URLContext *h, const char *uri, int flags)
  58 {
  59     char *node_uri = NULL, *tmp_uri;
  60     int err = 0;
  61     int64_t size;
  62     size_t  len, i;
  63     URLContext *uc;
  64     struct concat_data  *data = h->priv_data;
  65     struct concat_nodes *nodes;
  66
  67     av_strstart(uri, "concat:", &uri);
  68
  69     for (i = 0, len = 1; uri[i]; i++)
  70         if (uri[i] == *AV_CAT_SEPARATOR)
  71             /* integer overflow */
  72             if (++len == UINT_MAX / sizeof(*nodes)) {
  73                 av_freep(&h->priv_data);
  74                 return AVERROR(ENAMETOOLONG);
  75             }
  76
  77     if (!(nodes = av_malloc(sizeof(*nodes) * len))) {
  78         return AVERROR(ENOMEM);
  79     } else
  80         data->nodes = nodes;
  81
  82     /* handle input */
  83     if (!*uri)
  84         err = AVERROR(ENOENT);
  85     for (i = 0; *uri; i++) {
  86         /* parsing uri */
  87         len = strcspn(uri, AV_CAT_SEPARATOR);
  88         if (!(tmp_uri = av_realloc(node_uri, len+1))) {
  89             err = AVERROR(ENOMEM);
  90             break;
  91         } else
  92             node_uri = tmp_uri;
  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         total += result;
 141         buf   += result;
 142         size  -= result;
 143     }
 144     data->current = i;
 145     return total;
 146 }
 147
 148 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
 149 {
 150     int64_t result;
 151     struct concat_data  *data  = h->priv_data;
 152     struct concat_nodes *nodes = data->nodes;
 153     size_t i;
 154
 155     switch (whence) {
 156     case SEEK_END:
 157         for (i = data->length - 1;
 158              i && pos < -nodes[i].size;
 159              i--)
 160             pos += nodes[i].size;
 161         break;
 162     case SEEK_CUR:
 163         /* get the absolute position */
 164         for (i = 0; i != data->current; i++)
 165             pos += nodes[i].size;
 166         pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
 167         whence = SEEK_SET;
 168         /* fall through with the absolute position */
 169     case SEEK_SET:
 170         for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
 171             pos -= nodes[i].size;
 172         break;
 173     default:
 174         return AVERROR(EINVAL);
 175     }
 176
 177     result = ffurl_seek(nodes[i].uc, pos, whence);
 178     if (result >= 0) {
 179         data->current = i;
 180         while (i)
 181             result += nodes[--i].size;
 182     }
 183     return result;
 184 }
 185
 186 URLProtocol ff_concat_protocol = {
 187     .name           = "concat",
 188     .url_open       = concat_open,
 189     .url_read       = concat_read,
 190     .url_seek       = concat_seek,
 191     .url_close      = concat_close,
 192     .priv_data_size = sizeof(struct concat_data),
 193 };