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/*
* Copyright (c) 2014 Nicolas George
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/opt.h"
#include "avformat.h"
#include "url.h"
typedef struct SubfileContext {
const AVClass *class;
URLContext *h;
int64_t start;
int64_t end;
int64_t pos;
} SubfileContext;
#define OFFSET(field) offsetof(SubfileContext, field)
#define D AV_OPT_FLAG_DECODING_PARAM
static const AVOption subfile_options[] = {
{ "start", "start offset", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
{ "end", "end offset", OFFSET(end), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
{ NULL }
};
#undef OFFSET
#undef D
static const AVClass subfile_class = {
.class_name = "subfile",
.item_name = av_default_item_name,
.option = subfile_options,
.version = LIBAVUTIL_VERSION_INT,
};
static int slave_seek(URLContext *h)
{
SubfileContext *c = h->priv_data;
int64_t ret;
if ((ret = ffurl_seek(c->h, c->pos, SEEK_SET)) != c->pos) {
if (ret >= 0)
ret = AVERROR_BUG;
av_log(h, AV_LOG_ERROR, "Impossible to seek in file: %s\n",
av_err2str(ret));
return ret;
}
return 0;
}
static int subfile_open(URLContext *h, const char *filename, int flags,
AVDictionary **options)
{
SubfileContext *c = h->priv_data;
int ret;
if (c->end <= c->start) {
av_log(h, AV_LOG_ERROR, "end before start\n");
return AVERROR(EINVAL);
}
av_strstart(filename, "subfile:", &filename);
ret = ffurl_open_whitelist(&c->h, filename, flags, &h->interrupt_callback,
options, h->protocol_whitelist);
if (ret < 0)
return ret;
c->pos = c->start;
if ((ret = slave_seek(h)) < 0) {
ffurl_close(c->h);
return ret;
}
return 0;
}
static int subfile_close(URLContext *h)
{
SubfileContext *c = h->priv_data;
return ffurl_close(c->h);
}
static int subfile_read(URLContext *h, unsigned char *buf, int size)
{
SubfileContext *c = h->priv_data;
int64_t rest = c->end - c->pos;
int ret;
if (rest <= 0)
return 0;
size = FFMIN(size, rest);
ret = ffurl_read(c->h, buf, size);
if (ret >= 0)
c->pos += ret;
return ret;
}
static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
{
SubfileContext *c = h->priv_data;
int64_t new_pos = -1;
int ret;
if (whence == AVSEEK_SIZE)
return c->end - c->start;
switch (whence) {
case SEEK_SET:
new_pos = c->start + pos;
break;
case SEEK_CUR:
new_pos += pos;
break;
case SEEK_END:
new_pos = c->end + c->pos;
break;
}
if (new_pos < c->start)
return AVERROR(EINVAL);
c->pos = new_pos;
if ((ret = slave_seek(h)) < 0)
return ret;
return c->pos - c->start;
}
const URLProtocol ff_subfile_protocol = {
.name = "subfile",
.url_open2 = subfile_open,
.url_read = subfile_read,
.url_seek = subfile_seek,
.url_close = subfile_close,
.priv_data_size = sizeof(SubfileContext),
.priv_data_class = &subfile_class,
.default_whitelist = "file",
};
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