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 <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 */
ext2fs_check_desc(ext2_filsys fs)32 errcode_t ext2fs_check_desc(ext2_filsys fs)
33 {
34 ext2fs_block_bitmap bmap;
35 errcode_t retval;
36 dgrp_t i;
37 blk64_t first_block = fs->super->s_first_data_block;
38 blk64_t last_block = ext2fs_blocks_count(fs->super)-1;
39 blk64_t blk, b;
40 unsigned int j;
41
42 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
43
44 if (EXT2_DESC_SIZE(fs->super) & (EXT2_DESC_SIZE(fs->super) - 1))
45 return EXT2_ET_BAD_DESC_SIZE;
46
47 retval = ext2fs_allocate_subcluster_bitmap(fs, "check_desc map", &bmap);
48 if (retval)
49 return retval;
50
51 for (i = 0; i < fs->group_desc_count; i++)
52 ext2fs_reserve_super_and_bgd(fs, i, bmap);
53
54 for (i = 0; i < fs->group_desc_count; i++) {
55 if (!EXT2_HAS_INCOMPAT_FEATURE(fs->super,
56 EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
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 }
105