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 Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  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         ext2fs_block_bitmap bmap;
  36         errcode_t retval;
  37         dgrp_t i;
  38         blk64_t first_block = fs->super->s_first_data_block;
  39         blk64_t last_block = ext2fs_blocks_count(fs->super)-1;
  40         blk64_t blk, b;
  41         unsigned int j;
  42
  43         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  44
  45         if (EXT2_DESC_SIZE(fs->super) & (EXT2_DESC_SIZE(fs->super) - 1))
  46                 return EXT2_ET_BAD_DESC_SIZE;
  47
  48         retval = ext2fs_allocate_subcluster_bitmap(fs, "check_desc map", &bmap);
  49         if (retval)
  50                 return retval;
  51
  52         for (i = 0; i < fs->group_desc_count; i++)
  53                 ext2fs_reserve_super_and_bgd(fs, i, bmap);
  54
  55         for (i = 0; i < fs->group_desc_count; i++) {
  56                 if (!ext2fs_has_feature_flex_bg(fs->super)) {
  57                         first_block = ext2fs_group_first_block2(fs, i);
  58                         last_block = ext2fs_group_last_block2(fs, i);
  59                 }
  60
  61                 /*
  62                  * Check to make sure the block bitmap for group is sane
  63                  */
  64                 blk = ext2fs_block_bitmap_loc(fs, i);
  65                 if (blk < first_block || blk > last_block ||
  66                     ext2fs_test_block_bitmap2(bmap, blk)) {
  67                         retval = EXT2_ET_GDESC_BAD_BLOCK_MAP;
  68                         goto errout;
  69                 }
  70                 ext2fs_mark_block_bitmap2(bmap, blk);
  71
  72                 /*
  73                  * Check to make sure the inode bitmap for group is sane
  74                  */
  75                 blk = ext2fs_inode_bitmap_loc(fs, i);
  76                 if (blk < first_block || blk > last_block ||
  77                     ext2fs_test_block_bitmap2(bmap, blk)) {
  78                         retval = EXT2_ET_GDESC_BAD_INODE_MAP;
  79                         goto errout;
  80                 }
  81                 ext2fs_mark_block_bitmap2(bmap, blk);
  82
  83                 /*
  84                  * Check to make sure the inode table for group is sane
  85                  */
  86                 blk = ext2fs_inode_table_loc(fs, i);
  87                 if (blk < first_block ||
  88                     ((blk + fs->inode_blocks_per_group - 1) > last_block)) {
  89                         retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
  90                         goto errout;
  91                 }
  92                 for (j = 0, b = blk; j < fs->inode_blocks_per_group;
  93                      j++, b++) {
  94                         if (ext2fs_test_block_bitmap2(bmap, b)) {
  95                                 retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
  96                                 goto errout;
  97                         }
  98                         ext2fs_mark_block_bitmap2(bmap, b);
  99                 }
 100         }
 101 errout:
 102         ext2fs_free_block_bitmap(bmap);
 103         return retval;
 104 }