FFmpeg/libavformat/cache.c
Michael Niedermayer 0704c44d68 avformat/cache: remove ftruncate usage, its not always available
In case of errors the cache file will be slightly larger than needed,
this should have no practical relevance though

Should fix build on VS201*

Found-by: jamrial
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2014-12-26 12:41:15 +01:00

323 lines
8.6 KiB
C

/*
* Input cache protocol.
* Copyright (c) 2011,2014 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 keeping files
* support filling with a background thread
*/
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/file.h"
#include "libavutil/opt.h"
#include "libavutil/tree.h"
#include "avformat.h"
#include <fcntl.h>
#if HAVE_IO_H
#include <io.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <sys/stat.h>
#include <stdlib.h>
#include "os_support.h"
#include "url.h"
typedef struct CacheEntry {
int64_t logical_pos;
int64_t physical_pos;
int size;
} CacheEntry;
typedef struct Context {
AVClass *class;
int fd;
struct AVTreeNode *root;
int64_t logical_pos;
int64_t cache_pos;
int64_t inner_pos;
int64_t end;
int is_true_eof;
URLContext *inner;
int64_t cache_hit, cache_miss;
int read_ahead_limit;
} Context;
static int cmp(void *key, const void *node)
{
return (*(int64_t *) key) - ((const CacheEntry *) node)->logical_pos;
}
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 add_entry(URLContext *h, const unsigned char *buf, int size)
{
Context *c= h->priv_data;
int64_t pos = -1;
int ret;
CacheEntry *entry = NULL, *next[2] = {NULL, NULL};
CacheEntry *entry_ret;
struct AVTreeNode *node = NULL;
//FIXME avoid lseek
pos = lseek(c->fd, 0, SEEK_END);
if (pos < 0) {
ret = AVERROR(errno);
av_log(h, AV_LOG_ERROR, "seek in cache failed\n");
goto fail;
}
c->cache_pos = pos;
ret = write(c->fd, buf, size);
if (ret < 0) {
ret = AVERROR(errno);
av_log(h, AV_LOG_ERROR, "write in cache failed\n");
goto fail;
}
c->cache_pos += ret;
entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);
if (!entry)
entry = next[0];
if (!entry ||
entry->logical_pos + entry->size != c->logical_pos ||
entry->physical_pos + entry->size != pos
) {
entry = av_malloc(sizeof(*entry));
node = av_tree_node_alloc();
if (!entry || !node) {
ret = AVERROR(ENOMEM);
goto fail;
}
entry->logical_pos = c->logical_pos;
entry->physical_pos = pos;
entry->size = ret;
entry_ret = av_tree_insert(&c->root, entry, cmp, &node);
if (entry_ret && entry_ret != entry) {
ret = -1;
av_log(h, AV_LOG_ERROR, "av_tree_insert failed\n");
goto fail;
}
} else
entry->size += ret;
return 0;
fail:
//we could truncate the file to pos here if pos >=0 but ftruncate isnt available in VS so
//for simplicty we just leave the file a bit larger
av_free(entry);
av_free(node);
return ret;
}
static int cache_read(URLContext *h, unsigned char *buf, int size)
{
Context *c= h->priv_data;
CacheEntry *entry, *next[2] = {NULL, NULL};
int r;
entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);
if (!entry)
entry = next[0];
if (entry) {
int64_t in_block_pos = c->logical_pos - entry->logical_pos;
av_assert0(entry->logical_pos <= c->logical_pos);
if (in_block_pos < entry->size) {
int64_t physical_target = entry->physical_pos + in_block_pos;
if (c->cache_pos != physical_target) {
r = lseek(c->fd, physical_target, SEEK_SET);
} else
r = c->cache_pos;
if (r >= 0) {
c->cache_pos = r;
r = read(c->fd, buf, FFMIN(size, entry->size - in_block_pos));
}
if (r > 0) {
c->cache_pos += r;
c->logical_pos += r;
c->cache_hit ++;
return r;
}
}
}
// Cache miss or some kind of fault with the cache
if (c->logical_pos != c->inner_pos) {
r = ffurl_seek(c->inner, c->logical_pos, SEEK_SET);
if (r<0) {
av_log(h, AV_LOG_ERROR, "Failed to perform internal seek\n");
return r;
}
c->inner_pos = r;
}
r = ffurl_read(c->inner, buf, size);
if (r == 0 && size>0) {
c->is_true_eof = 1;
av_assert0(c->end >= c->logical_pos);
}
if (r<=0)
return r;
c->inner_pos += r;
c->cache_miss ++;
add_entry(h, buf, r);
c->logical_pos += r;
c->end = FFMAX(c->end, c->logical_pos);
return r;
}
static int64_t cache_seek(URLContext *h, int64_t pos, int whence)
{
Context *c= h->priv_data;
int64_t ret;
if (whence == AVSEEK_SIZE) {
pos= ffurl_seek(c->inner, pos, whence);
if(pos <= 0){
pos= ffurl_seek(c->inner, -1, SEEK_END);
if (ffurl_seek(c->inner, c->inner_pos, SEEK_SET) < 0)
av_log(h, AV_LOG_ERROR, "Inner protocol failed to seekback end : %"PRId64"\n", pos);
}
if (pos > 0)
c->is_true_eof = 1;
c->end = FFMAX(c->end, pos);
return pos;
}
if (whence == SEEK_CUR) {
whence = SEEK_SET;
pos += c->logical_pos;
} else if (whence == SEEK_END && c->is_true_eof) {
resolve_eof:
whence = SEEK_SET;
pos += c->end;
}
if (whence == SEEK_SET && pos >= 0 && pos < c->end) {
//Seems within filesize, assume it will not fail.
c->logical_pos = pos;
return pos;
}
//cache miss
ret= ffurl_seek(c->inner, pos, whence);
if ((whence == SEEK_SET && pos >= c->logical_pos ||
whence == SEEK_END && pos <= 0) && ret < 0) {
if ( (whence == SEEK_SET && c->read_ahead_limit >= pos - c->logical_pos)
|| c->read_ahead_limit < 0) {
uint8_t tmp[32768];
while (c->logical_pos < pos || whence == SEEK_END) {
int size = sizeof(tmp);
if (whence == SEEK_SET)
size = FFMIN(sizeof(tmp), pos - c->logical_pos);
ret = cache_read(h, tmp, size);
if (ret == 0 && whence == SEEK_END) {
av_assert0(c->is_true_eof);
goto resolve_eof;
}
if (ret < 0) {
return ret;
}
}
return c->logical_pos;
}
}
if (ret >= 0) {
c->logical_pos = ret;
c->end = FFMAX(c->end, ret);
}
return ret;
}
static int cache_close(URLContext *h)
{
Context *c= h->priv_data;
av_log(h, AV_LOG_INFO, "Statistics, cache hits:%"PRId64" cache misses:%"PRId64"\n",
c->cache_hit, c->cache_miss);
close(c->fd);
ffurl_close(c->inner);
av_tree_destroy(c->root);
return 0;
}
#define OFFSET(x) offsetof(Context, x)
#define D AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
{ "read_ahead_limit", "Amount in bytes that may be read ahead when seeking isnt supported, -1 for unlimited", OFFSET(read_ahead_limit), AV_OPT_TYPE_INT, { .i64 = 65536 }, -1, INT_MAX, D },
{NULL},
};
static const AVClass cache_context_class = {
.class_name = "Cache",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
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),
.priv_data_class = &cache_context_class,
};