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         ext2fs_block_bitmap bmap;
  35         errcode_t retval;
  36         dgrp_t i;
  37         blk_t first_block = fs->super->s_first_data_block;
  38         blk_t last_block = ext2fs_blocks_count(fs->super)-1;
  39         blk64_t blk, b;
  40         int j;
  41
  42         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  43
  44         retval = ext2fs_allocate_block_bitmap(fs, "check_desc map", &bmap);
  45         if (retval)
  46                 return retval;
  47
  48         for (i = 0; i < fs->group_desc_count; i++)
  49                 ext2fs_reserve_super_and_bgd(fs, i, bmap);
  50
  51         for (i = 0; i < fs->group_desc_count; i++) {
  52                 if (!EXT2_HAS_INCOMPAT_FEATURE(fs->super,
  53                                                EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
  54                         first_block = ext2fs_group_first_block2(fs, i);
  55                         last_block = ext2fs_group_last_block2(fs, i);
  56                         if (i == (fs->group_desc_count - 1))
  57                                 last_block = ext2fs_blocks_count(fs->super)-1;
  58                 }
  59
  60                 /*
  61                  * Check to make sure the block bitmap for group is sane
  62                  */
  63                 blk = ext2fs_block_bitmap_loc(fs, i);
  64                 if (blk < first_block || blk > last_block ||
  65                     ext2fs_test_block_bitmap2(bmap, blk)) {
  66                         retval = EXT2_ET_GDESC_BAD_BLOCK_MAP;
  67                         goto errout;
  68                 }
  69                 ext2fs_mark_block_bitmap2(bmap, blk);
  70
  71                 /*
  72                  * Check to make sure the inode bitmap for group is sane
  73                  */
  74                 blk = ext2fs_inode_bitmap_loc(fs, i);
  75                 if (blk < first_block || blk > last_block ||
  76                     ext2fs_test_block_bitmap2(bmap, blk)) {
  77                         retval = EXT2_ET_GDESC_BAD_INODE_MAP;
  78                         goto errout;
  79                 }
  80                 ext2fs_mark_block_bitmap2(bmap, blk);
  81
  82                 /*
  83                  * Check to make sure the inode table for group is sane
  84                  */
  85                 blk = ext2fs_inode_table_loc(fs, i);
  86                 if (blk < first_block ||
  87                     ((blk + fs->inode_blocks_per_group - 1) > last_block)) {
  88                         retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
  89                         goto errout;
  90                 }
  91                 for (j = 0, b = blk; j < fs->inode_blocks_per_group;
  92                      j++, b++) {
  93                         if (ext2fs_test_block_bitmap2(bmap, b)) {
  94                                 retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
  95                                 goto errout;
  96                         }
  97                         ext2fs_mark_block_bitmap2(bmap, b);
  98                 }
  99         }
 100 errout:
 101         ext2fs_free_block_bitmap(bmap);
 102         return retval;
 103 }