Libav
concat.c
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1 /*
2  * Concat URL protocol
3  * Copyright (c) 2006 Steve Lhomme
4  * Copyright (c) 2007 Wolfram Gloger
5  * Copyright (c) 2010 Michele OrrĂ¹
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 {
33  int64_t size;
34 };
35 
36 struct concat_data {
37  struct concat_nodes *nodes;
38  size_t length;
39  size_t current;
40 };
41 
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;
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_realloc(NULL, 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 ((err = av_reallocp(&node_uri, len + 1)) < 0)
89  break;
90  av_strlcpy(node_uri, uri, len+1);
91  uri += len + strspn(uri+len, AV_CAT_SEPARATOR);
92 
93  /* creating URLContext */
94  if ((err = ffurl_open(&uc, node_uri, flags,
95  &h->interrupt_callback, NULL)) < 0)
96  break;
97 
98  /* creating size */
99  if ((size = ffurl_size(uc)) < 0) {
100  ffurl_close(uc);
101  err = AVERROR(ENOSYS);
102  break;
103  }
104 
105  /* assembling */
106  nodes[i].uc = uc;
107  nodes[i].size = size;
108  }
109  av_free(node_uri);
110  data->length = i;
111 
112  if (err < 0)
113  concat_close(h);
114  else if ((err = av_reallocp(&nodes, data->length * sizeof(*nodes))) < 0)
115  concat_close(h);
116  else
117  data->nodes = nodes;
118  return err;
119 }
120 
121 static int concat_read(URLContext *h, unsigned char *buf, int size)
122 {
123  int result, total = 0;
124  struct concat_data *data = h->priv_data;
125  struct concat_nodes *nodes = data->nodes;
126  size_t i = data->current;
127 
128  while (size > 0) {
129  result = ffurl_read(nodes[i].uc, buf, size);
130  if (result < 0)
131  return total ? total : result;
132  if (!result)
133  if (i + 1 == data->length ||
134  ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
135  break;
136  total += result;
137  buf += result;
138  size -= result;
139  }
140  data->current = i;
141  return total;
142 }
143 
144 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
145 {
146  int64_t result;
147  struct concat_data *data = h->priv_data;
148  struct concat_nodes *nodes = data->nodes;
149  size_t i;
150 
151  switch (whence) {
152  case SEEK_END:
153  for (i = data->length - 1;
154  i && pos < -nodes[i].size;
155  i--)
156  pos += nodes[i].size;
157  break;
158  case SEEK_CUR:
159  /* get the absolute position */
160  for (i = 0; i != data->current; i++)
161  pos += nodes[i].size;
162  pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
163  whence = SEEK_SET;
164  /* fall through with the absolute position */
165  case SEEK_SET:
166  for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
167  pos -= nodes[i].size;
168  break;
169  default:
170  return AVERROR(EINVAL);
171  }
172 
173  result = ffurl_seek(nodes[i].uc, pos, whence);
174  if (result >= 0) {
175  data->current = i;
176  while (i)
177  result += nodes[--i].size;
178  }
179  return result;
180 }
181 
183  .name = "concat",
184  .url_open = concat_open,
185  .url_read = concat_read,
186  .url_seek = concat_seek,
187  .url_close = concat_close,
188  .priv_data_size = sizeof(struct concat_data),
189 };