ref: b3ec2b25f88be6d9ec861e789763225906d9935c
dir: /blockdev/linux/ext4_filedev.c/
/*
* Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64
#include <ext4_config.h>
#include <ext4_blockdev.h>
#include <ext4_errno.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
/**@brief Default filename.*/
static const char *fname = "ext2";
/**@brief Image block size.*/
#define EXT4_FILEDEV_BSIZE 512
/**@brief Image file descriptor.*/
static FILE *dev_file;
#define DROP_LINUXCACHE_BUFFERS 0
/**********************BLOCKDEV INTERFACE**************************************/
static int filedev_open(struct ext4_blockdev *bdev);
static int filedev_bread(struct ext4_blockdev *bdev, void *buf, uint64_t blk_id,
uint32_t blk_cnt);
static int filedev_bwrite(struct ext4_blockdev *bdev, const void *buf,
uint64_t blk_id, uint32_t blk_cnt);
static int filedev_close(struct ext4_blockdev *bdev);
/******************************************************************************/
EXT4_BLOCKDEV_STATIC_INSTANCE(_filedev, EXT4_FILEDEV_BSIZE, 0, filedev_open,
filedev_bread, filedev_bwrite, filedev_close);
/******************************************************************************/
static int filedev_open(struct ext4_blockdev *bdev)
{
dev_file = fopen(fname, "r+b");
if (!dev_file)
return EIO;
/*No buffering at file.*/
setbuf(dev_file, 0);
if (fseeko(dev_file, 0, SEEK_END))
return EFAULT;
_filedev.ph_bcnt = ftell(dev_file) / _filedev.ph_bsize;
return EOK;
}
/******************************************************************************/
static int filedev_bread(struct ext4_blockdev *bdev, void *buf, uint64_t blk_id,
uint32_t blk_cnt)
{
if (fseeko(dev_file, blk_id * bdev->ph_bsize, SEEK_SET))
return EIO;
if (!blk_cnt)
return EOK;
if (!fread(buf, bdev->ph_bsize * blk_cnt, 1, dev_file))
return EIO;
return EOK;
}
static void drop_cache(void)
{
#if defined(__linux__) && DROP_LINUXCACHE_BUFFERS
int fd;
char *data = "3";
sync();
fd = open("/proc/sys/vm/drop_caches", O_WRONLY);
write(fd, data, sizeof(char));
close(fd);
#endif
}
/******************************************************************************/
static int filedev_bwrite(struct ext4_blockdev *bdev, const void *buf,
uint64_t blk_id, uint32_t blk_cnt)
{
if (fseeko(dev_file, blk_id * bdev->ph_bsize, SEEK_SET))
return EIO;
if (!blk_cnt)
return EOK;
if (!fwrite(buf, bdev->ph_bsize * blk_cnt, 1, dev_file))
return EIO;
drop_cache();
return EOK;
}
/******************************************************************************/
static int filedev_close(struct ext4_blockdev *bdev)
{
fclose(dev_file);
return EOK;
}
/******************************************************************************/
struct ext4_blockdev *ext4_filedev_get(void) { return &_filedev; }
/******************************************************************************/
void ext4_filedev_filename(const char *n) { fname = n; }
/******************************************************************************/