lib/ext2fs/check_desc.c

   1 /*
   2  * check_desc.c --- Check the group descriptors of an ext2 filesystem
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Public
   8  * License.
   9  * %End-Header%
  10  */
  11
  12 #include <stdio.h>
  13 #include <string.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <fcntl.h>
  18 #include <time.h>
  19 #if HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #if HAVE_SYS_TYPES_H
  23 #include <sys/types.h>
  24 #endif
  25
  26 #include "ext2_fs.h"
  27 #include "ext2fs.h"
  28
  29 /*
  30  * This routine sanity checks the group descriptors
  31  */
  32 errcode_t ext2fs_check_desc(ext2_filsys fs)
  33 {
  34         int i;
  35         blk_t block = fs->super->s_first_data_block;
  36         blk_t next;
  37
  38         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  39
  40         for (i = 0; i < fs->group_desc_count; i++) {
  41                 next = block + fs->super->s_blocks_per_group;
  42                 /*
  43                  * Check to make sure block bitmap for group is
  44                  * located within the group.
  45                  */
  46                 if (fs->group_desc[i].bg_block_bitmap < block ||
  47                     fs->group_desc[i].bg_block_bitmap >= next)
  48                         return EXT2_ET_GDESC_BAD_BLOCK_MAP;
  49                 /*
  50                  * Check to make sure inode bitmap for group is
  51                  * located within the group
  52                  */
  53                 if (fs->group_desc[i].bg_inode_bitmap < block ||
  54                     fs->group_desc[i].bg_inode_bitmap >= next)
  55                         return EXT2_ET_GDESC_BAD_INODE_MAP;
  56                 /*
  57                  * Check to make sure inode table for group is located
  58                  * within the group
  59                  */
  60                 if (fs->group_desc[i].bg_inode_table < block ||
  61                     ((fs->group_desc[i].bg_inode_table +
  62                       fs->inode_blocks_per_group) >= next))
  63                         return EXT2_ET_GDESC_BAD_INODE_TABLE;
  64
  65                 block = next;
  66         }
  67         return 0;
  68 }