yading@11: /*
yading@11:  * Input cache protocol.
yading@11:  * Copyright (c) 2011 Michael Niedermayer
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  *
yading@11:  * Based on file.c by Fabrice Bellard
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * @TODO
yading@11:  *      support non continuous caching
yading@11:  *      support keeping files
yading@11:  *      support filling with a background thread
yading@11:  */
yading@11: 
yading@11: #include "libavutil/avassert.h"
yading@11: #include "libavutil/avstring.h"
yading@11: #include "libavutil/file.h"
yading@11: #include "avformat.h"
yading@11: #include <fcntl.h>
yading@11: #if HAVE_IO_H
yading@11: #include <io.h>
yading@11: #endif
yading@11: #if HAVE_UNISTD_H
yading@11: #include <unistd.h>
yading@11: #endif
yading@11: #include <sys/stat.h>
yading@11: #include <stdlib.h>
yading@11: #include "os_support.h"
yading@11: #include "url.h"
yading@11: 
yading@11: typedef struct Context {
yading@11:     int fd;
yading@11:     int64_t end;
yading@11:     int64_t pos;
yading@11:     URLContext *inner;
yading@11: } Context;
yading@11: 
yading@11: static int cache_open(URLContext *h, const char *arg, int flags)
yading@11: {
yading@11:     char *buffername;
yading@11:     Context *c= h->priv_data;
yading@11: 
yading@11:     av_strstart(arg, "cache:", &arg);
yading@11: 
yading@11:     c->fd = av_tempfile("ffcache", &buffername, 0, h);
yading@11:     if (c->fd < 0){
yading@11:         av_log(h, AV_LOG_ERROR, "Failed to create tempfile\n");
yading@11:         return c->fd;
yading@11:     }
yading@11: 
yading@11:     unlink(buffername);
yading@11:     av_freep(&buffername);
yading@11: 
yading@11:     return ffurl_open(&c->inner, arg, flags, &h->interrupt_callback, NULL);
yading@11: }
yading@11: 
yading@11: static int cache_read(URLContext *h, unsigned char *buf, int size)
yading@11: {
yading@11:     Context *c= h->priv_data;
yading@11:     int r;
yading@11: 
yading@11:     if(c->pos<c->end){
yading@11:         r = read(c->fd, buf, FFMIN(size, c->end - c->pos));
yading@11:         if(r>0)
yading@11:             c->pos += r;
yading@11:         return (-1 == r)?AVERROR(errno):r;
yading@11:     }else{
yading@11:         r = ffurl_read(c->inner, buf, size);
yading@11:         if(r > 0){
yading@11:             int r2= write(c->fd, buf, r);
yading@11:             av_assert0(r2==r); // FIXME handle cache failure
yading@11:             c->pos += r;
yading@11:             c->end += r;
yading@11:         }
yading@11:         return r;
yading@11:     }
yading@11: }
yading@11: 
yading@11: static int64_t cache_seek(URLContext *h, int64_t pos, int whence)
yading@11: {
yading@11:     Context *c= h->priv_data;
yading@11: 
yading@11:     if (whence == AVSEEK_SIZE) {
yading@11:         pos= ffurl_seek(c->inner, pos, whence);
yading@11:         if(pos <= 0){
yading@11:             pos= ffurl_seek(c->inner, -1, SEEK_END);
yading@11:             ffurl_seek(c->inner, c->end, SEEK_SET);
yading@11:             if(pos <= 0)
yading@11:                 return c->end;
yading@11:         }
yading@11:         return pos;
yading@11:     }
yading@11: 
yading@11:     pos= lseek(c->fd, pos, whence);
yading@11:     if(pos<0){
yading@11:         return pos;
yading@11:     }else if(pos <= c->end){
yading@11:         c->pos= pos;
yading@11:         return pos;
yading@11:     }else{
yading@11:         if(lseek(c->fd, c->pos, SEEK_SET) < 0) {
yading@11:             av_log(h, AV_LOG_ERROR, "Failure to seek in cache\n");
yading@11:         }
yading@11:         return AVERROR(EPIPE);
yading@11:     }
yading@11: }
yading@11: 
yading@11: static int cache_close(URLContext *h)
yading@11: {
yading@11:     Context *c= h->priv_data;
yading@11:     close(c->fd);
yading@11:     ffurl_close(c->inner);
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: URLProtocol ff_cache_protocol = {
yading@11:     .name                = "cache",
yading@11:     .url_open            = cache_open,
yading@11:     .url_read            = cache_read,
yading@11:     .url_seek            = cache_seek,
yading@11:     .url_close           = cache_close,
yading@11:     .priv_data_size      = sizeof(Context),
yading@11: };