release/src/router/busybox/e2fsprogs/old_e2fsprogs/ext2fs/check_desc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * check_desc.c --- Check the group descriptors of an ext2 filesystem
   4  *
   5  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #if HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #if HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26
  27 #include "ext2_fs.h"
  28 #include "ext2fs.h"
  29
  30 /*
  31  * This routine sanity checks the group descriptors
  32  */
  33 errcode_t ext2fs_check_desc(ext2_filsys fs)
  34 {
  35         dgrp_t i;
  36         blk_t block = fs->super->s_first_data_block;
  37         blk_t next;
  38
  39         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  40
  41         for (i = 0; i < fs->group_desc_count; i++) {
  42                 next = block + fs->super->s_blocks_per_group;
  43                 /*
  44                  * Check to make sure block bitmap for group is
  45                  * located within the group.
  46                  */
  47                 if (fs->group_desc[i].bg_block_bitmap < block ||
  48                     fs->group_desc[i].bg_block_bitmap >= next)
  49                         return EXT2_ET_GDESC_BAD_BLOCK_MAP;
  50                 /*
  51                  * Check to make sure inode bitmap for group is
  52                  * located within the group
  53                  */
  54                 if (fs->group_desc[i].bg_inode_bitmap < block ||
  55                     fs->group_desc[i].bg_inode_bitmap >= next)
  56                         return EXT2_ET_GDESC_BAD_INODE_MAP;
  57                 /*
  58                  * Check to make sure inode table for group is located
  59                  * within the group
  60                  */
  61                 if (fs->group_desc[i].bg_inode_table < block ||
  62                     ((fs->group_desc[i].bg_inode_table +
  63                       fs->inode_blocks_per_group) >= next))
  64                         return EXT2_ET_GDESC_BAD_INODE_TABLE;
  65
  66                 block = next;
  67         }
  68         return 0;
  69 }