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     uint64_t total_size;
  42 };
  43
  44 static av_cold int concat_close(URLContext *h)
  45 {
  46     int err = 0;
  47     size_t i;
  48     struct concat_data  *data  = h->priv_data;
  49     struct concat_nodes *nodes = data->nodes;
  50
  51     for (i = 0; i != data->length; i++)
  52         err |= ffurl_closep(&nodes[i].uc);
  53
  54     av_freep(&data->nodes);
  55
  56     return err < 0 ? -1 : 0;
  57 }
  58
  59 static av_cold int concat_open(URLContext *h, const char *uri, int flags)
  60 {
  61     char *node_uri = NULL;
  62     int err = 0;
  63     int64_t size, total_size = 0;
  64     size_t len, i;
  65     URLContext *uc;
  66     struct concat_data  *data = h->priv_data;
  67     struct concat_nodes *nodes;
  68
  69     if (!av_strstart(uri, "concat:", &uri)) {
  70         av_log(h, AV_LOG_ERROR, "URL %s lacks prefix\n", uri);
  71         return AVERROR(EINVAL);
  72     }
  73
  74     for (i = 0, len = 1; uri[i]; i++) {
  75         if (uri[i] == *AV_CAT_SEPARATOR) {
  76             /* integer overflow */
  77             if (++len == UINT_MAX / sizeof(*nodes)) {
  78                 return AVERROR(ENAMETOOLONG);
  79             }
  80         }
  81     }
  82
  83     if (!(nodes = av_realloc(NULL, sizeof(*nodes) * len)))
  84         return AVERROR(ENOMEM);
  85     else
  86         data->nodes = nodes;
  87
  88     /* handle input */
  89     if (!*uri)
  90         err = AVERROR(ENOENT);
  91     for (i = 0; *uri; i++) {
  92         /* parsing uri */
  93         len = strcspn(uri, AV_CAT_SEPARATOR);
  94         if ((err = av_reallocp(&node_uri, len + 1)) < 0)
  95             break;
  96         av_strlcpy(node_uri, uri, len + 1);
  97         uri += len + strspn(uri + len, AV_CAT_SEPARATOR);
  98
  99         /* creating URLContext */
 100         err = ffurl_open_whitelist(&uc, node_uri, flags,
 101                                    &h->interrupt_callback, NULL, h->protocol_whitelist, h->protocol_blacklist, h);
 102         if (err < 0)
 103             break;
 104
 105         /* creating size */
 106         if ((size = ffurl_size(uc)) < 0) {
 107             ffurl_close(uc);
 108             err = AVERROR(ENOSYS);
 109             break;
 110         }
 111
 112         /* assembling */
 113         nodes[i].uc   = uc;
 114         nodes[i].size = size;
 115         total_size += size;
 116     }
 117     av_free(node_uri);
 118     data->length = i;
 119
 120     if (err < 0)
 121         concat_close(h);
 122     else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
 123         concat_close(h);
 124         err = AVERROR(ENOMEM);
 125     } else
 126         data->nodes = nodes;
 127     data->total_size = total_size;
 128     return err;
 129 }
 130
 131 static int concat_read(URLContext *h, unsigned char *buf, int size)
 132 {
 133     int result, total = 0;
 134     struct concat_data  *data  = h->priv_data;
 135     struct concat_nodes *nodes = data->nodes;
 136     size_t i                   = data->current;
 137
 138     while (size > 0) {
 139         result = ffurl_read(nodes[i].uc, buf, size);
 140         if (result == AVERROR_EOF) {
 141             if (i + 1 == data->length ||
 142                 ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
 143                 break;
 144             result = 0;
 145         }
 146         if (result < 0)
 147             return total ? total : result;
 148         total += result;
 149         buf   += result;
 150         size  -= result;
 151     }
 152     data->current = i;
 153     return total ? total : result;
 154 }
 155
 156 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
 157 {
 158     int64_t result;
 159     struct concat_data  *data  = h->priv_data;
 160     struct concat_nodes *nodes = data->nodes;
 161     size_t i;
 162
 163     if ((whence & AVSEEK_SIZE))
 164         return data->total_size;
 165     switch (whence) {
 166     case SEEK_END:
 167         for (i = data->length - 1; i && pos < -nodes[i].size; i--)
 168             pos += nodes[i].size;
 169         break;
 170     case SEEK_CUR:
 171         /* get the absolute position */
 172         for (i = 0; i != data->current; i++)
 173             pos += nodes[i].size;
 174         pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
 175         whence = SEEK_SET;
 176         /* fall through with the absolute position */
 177     case SEEK_SET:
 178         for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
 179             pos -= nodes[i].size;
 180         break;
 181     default:
 182         return AVERROR(EINVAL);
 183     }
 184
 185     result = ffurl_seek(nodes[i].uc, pos, whence);
 186     if (result >= 0) {
 187         data->current = i;
 188         while (i)
 189             result += nodes[--i].size;
 190     }
 191     return result;
 192 }
 193
 194 const URLProtocol ff_concat_protocol = {
 195     .name           = "concat",
 196     .url_open       = concat_open,
 197     .url_read       = concat_read,
 198     .url_seek       = concat_seek,
 199     .url_close      = concat_close,
 200     .priv_data_size = sizeof(struct concat_data),
 201     .default_whitelist = "concat,file,subfile",
 202 };