blockdev/filedev/ext4_filedev.c

   1 /*
   2  * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  * - Redistributions in binary form must reproduce the above copyright
  12  *   notice, this list of conditions and the following disclaimer in the
  13  *   documentation and/or other materials provided with the distribution.
  14  * - The name of the author may not be used to endorse or promote products
  15  *   derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28 #include <ext4_config.h>
  29 #include <ext4_blockdev.h>
  30 #include <ext4_errno.h>
  31 #include <stdio.h>
  32 #include <stdbool.h>
  33 #include <string.h>
  34 #include <fcntl.h>
  35
  36 /**@brief       Default filename.*/
  37 static const char *fname = "ext2";
  38
  39 /**@brief       Image block size.*/
  40 #define EXT4_FILEDEV_BSIZE              512
  41
  42 /**@brief       Image file descriptor.*/
  43 static FILE     *dev_file;
  44
  45 #define DROP_LINUXCACHE_BUFFERS 1
  46
  47
  48 /**********************BLOCKDEV INTERFACE**************************************/
  49 static int filedev_open(struct ext4_blockdev *bdev);
  50 static int filedev_bread(struct ext4_blockdev *bdev, void *buf, uint64_t blk_id,
  51                 uint32_t blk_cnt);
  52 static int filedev_bwrite(struct ext4_blockdev *bdev, const void *buf,
  53                 uint64_t blk_id, uint32_t blk_cnt);
  54 static int filedev_close(struct  ext4_blockdev *bdev);
  55
  56
  57 /******************************************************************************/
  58 EXT4_BLOCKDEV_STATIC_INSTANCE(
  59                 _filedev,
  60                 EXT4_FILEDEV_BSIZE,
  61                 0,
  62                 filedev_open,
  63                 filedev_bread,
  64                 filedev_bwrite,
  65                 filedev_close
  66 );
  67
  68 /******************************************************************************/
  69 EXT4_BCACHE_STATIC_INSTANCE(__cache, CONFIG_BLOCK_DEV_CACHE_SIZE, 1024);
  70
  71 /******************************************************************************/
  72 static int filedev_open(struct ext4_blockdev *bdev)
  73 {
  74         dev_file = fopen(fname, "r+b");
  75
  76         if(!dev_file)
  77                 return EIO;
  78
  79         /*No buffering at file.*/
  80         setbuf(dev_file, 0);
  81
  82         if(fseek(dev_file, 0, SEEK_END))
  83                 return EFAULT;
  84
  85         _filedev.ph_bcnt = ftell(dev_file) / _filedev.ph_bsize;
  86
  87         return EOK;
  88 }
  89
  90 /******************************************************************************/
  91
  92 static int filedev_bread(struct  ext4_blockdev *bdev, void *buf, uint64_t blk_id,
  93                 uint32_t blk_cnt)
  94 {
  95         if(fseek(dev_file, blk_id * bdev->ph_bsize, SEEK_SET))
  96                 return EIO;
  97
  98         if(!fread(buf, bdev->ph_bsize * blk_cnt, 1, dev_file))
  99                 return EIO;
 100
 101         return EOK;
 102 }
 103
 104 static void drop_cache(void)
 105 {
 106 #if defined(__linux__) && DROP_LINUXCACHE_BUFFERS
 107     int fd;
 108     char* data = "3";
 109
 110     sync();
 111     fd = open("/proc/sys/vm/drop_caches", O_WRONLY);
 112     write(fd, data, sizeof(char));
 113     close(fd);
 114 #endif
 115 }
 116
 117 /******************************************************************************/
 118 static int filedev_bwrite(struct ext4_blockdev *bdev, const void *buf,
 119     uint64_t blk_id, uint32_t blk_cnt)
 120 {
 121     if(fseek(dev_file, blk_id * bdev->ph_bsize, SEEK_SET))
 122         return EIO;
 123
 124     if(!fwrite(buf, bdev->ph_bsize * blk_cnt, 1, dev_file))
 125         return EIO;
 126
 127     drop_cache();
 128     return EOK;
 129 }
 130 /******************************************************************************/
 131 static int filedev_close(struct  ext4_blockdev *bdev)
 132 {
 133         fclose(dev_file);
 134         return EOK;
 135 }
 136
 137
 138 /******************************************************************************/
 139
 140 struct  ext4_bcache* ext4_filecache_get(void)
 141 {
 142         return &__cache;
 143 }
 144 /******************************************************************************/
 145 struct  ext4_blockdev* ext4_filedev_get(void)
 146 {
 147         return &_filedev;
 148 }
 149 /******************************************************************************/
 150 void ext4_filedev_filename(const char *n)
 151 {
 152         fname = n;
 153 }
 154
 155 /******************************************************************************/