/* * 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) { 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_freep(&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), };