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