1/*
2 * Concat URL protocol
3 * Copyright (c) 2006 Steve Lhomme
4 * Copyright (c) 2007 Wolfram Gloger
5 * Copyright (c) 2010 Michele Orr��
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 "avformat.h"
25#include "libavutil/avstring.h"
26#include "libavutil/mem.h"
27#include "url.h"
28
29#define AV_CAT_SEPARATOR "|"
30
31struct concat_nodes {
32    URLContext *uc;                ///< node's URLContext
33    int64_t     size;              ///< url filesize
34};
35
36struct 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
42static 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
57static 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 (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
115        concat_close(h);
116        err = AVERROR(ENOMEM);
117    } else
118        data->nodes = nodes;
119    return err;
120}
121
122static int concat_read(URLContext *h, unsigned char *buf, int size)
123{
124    int result, total = 0;
125    struct concat_data  *data  = h->priv_data;
126    struct concat_nodes *nodes = data->nodes;
127    size_t i = data->current;
128
129    while (size > 0) {
130        result = ffurl_read(nodes[i].uc, buf, size);
131        if (result < 0)
132            return total ? total : result;
133        if (!result)
134            if (i + 1 == data->length ||
135                ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)
136                break;
137        total += result;
138        buf   += result;
139        size  -= result;
140    }
141    data->current = i;
142    return total;
143}
144
145static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
146{
147    int64_t result;
148    struct concat_data  *data  = h->priv_data;
149    struct concat_nodes *nodes = data->nodes;
150    size_t i;
151
152    switch (whence) {
153    case SEEK_END:
154        for (i = data->length - 1;
155             i && pos < -nodes[i].size;
156             i--)
157            pos += nodes[i].size;
158        break;
159    case SEEK_CUR:
160        /* get the absolute position */
161        for (i = 0; i != data->current; i++)
162            pos += nodes[i].size;
163        pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);
164        whence = SEEK_SET;
165        /* fall through with the absolute position */
166    case SEEK_SET:
167        for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
168            pos -= nodes[i].size;
169        break;
170    default:
171        return AVERROR(EINVAL);
172    }
173
174    result = ffurl_seek(nodes[i].uc, pos, whence);
175    if (result >= 0) {
176        data->current = i;
177        while (i)
178            result += nodes[--i].size;
179    }
180    return result;
181}
182
183URLProtocol ff_concat_protocol = {
184    .name           = "concat",
185    .url_open       = concat_open,
186    .url_read       = concat_read,
187    .url_seek       = concat_seek,
188    .url_close      = concat_close,
189    .priv_data_size = sizeof(struct concat_data),
190};
191