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/*
* Input cache protocol.
* Copyright (c) 2011 Michael Niedermayer
*
* 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
*
* Based on file.c by Fabrice Bellard
*/
/**
* @TODO
* support non continuous caching
* support keeping files
* support filling with a background thread
*/
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/file.h"
#include "avformat.h"
#include <fcntl.h>
#if HAVE_SETMODE
#include <io.h>
#endif
#include <unistd.h>
#include <sys/stat.h>
#include <stdlib.h>
#include "os_support.h"
#include "url.h"
typedef struct Context {
int fd;
int64_t end;
int64_t pos;
URLContext *inner;
} Context;
static int cache_open(URLContext *h, const char *arg, int flags)
{
const char *buffername;
Context *c= h->priv_data;
av_strstart(arg, "cache:", &arg);
c->fd = av_tempfile("ffcache", &buffername, 0, h);
if (c->fd < 0){
av_log(h, AV_LOG_ERROR, "Failed to create tempfile\n");
return c->fd;
}
unlink(buffername);
av_free(buffername);
return ffurl_open(&c->inner, arg, flags, &h->interrupt_callback, NULL);
}
static int cache_read(URLContext *h, unsigned char *buf, int size)
{
Context *c= h->priv_data;
int r;
if(c->pos<c->end){
r = read(c->fd, buf, FFMIN(size, c->end - c->pos));
if(r>0)
c->pos += r;
return (-1 == r)?AVERROR(errno):r;
}else{
r = ffurl_read(c->inner, buf, size);
if(r > 0){
int r2= write(c->fd, buf, r);
av_assert0(r2==r); // FIXME handle cache failure
c->pos += r;
c->end += r;
}
return r;
}
}
static int64_t cache_seek(URLContext *h, int64_t pos, int whence)
{
Context *c= h->priv_data;
if (whence == AVSEEK_SIZE) {
pos= ffurl_seek(c->inner, pos, whence);
if(pos <= 0){
pos= ffurl_seek(c->inner, -1, SEEK_END);
ffurl_seek(c->inner, c->end, SEEK_SET);
if(pos <= 0)
return c->end;
}
return pos;
}
pos= lseek(c->fd, pos, whence);
if(pos<0){
return pos;
}else if(pos <= c->end){
c->pos= pos;
return pos;
}else{
lseek(c->fd, c->pos, SEEK_SET);
return AVERROR(EPIPE);
}
}
static int cache_close(URLContext *h)
{
Context *c= h->priv_data;
close(c->fd);
ffurl_close(c->inner);
return 0;
}
URLProtocol ff_cache_protocol = {
.name = "cache",
.url_open = cache_open,
.url_read = cache_read,
.url_seek = cache_seek,
.url_close = cache_close,
.priv_data_size = sizeof(Context),
};
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