ref: 16b7ebbb8f420dceb77baa18918ea5c7af0a156e
dir: /blockdev/linux/ext4_filedev.c/
/* * Copyright (c) 2013 Grzegorz Kostka ([email protected]) * 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 (!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 (!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; } /******************************************************************************/