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 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
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, *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
125static 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
148static 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
186URLProtocol 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};
194