check_desc.c revision 543547a52a20cb7e69d74921b2f691078fd55d83 
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 */
32errcode_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 = fs->super->s_blocks_count-1;
39	blk_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_block(fs, i);
55			last_block = ext2fs_group_last_block(fs, i);
56			if (i == (fs->group_desc_count - 1))
57				last_block = fs->super->s_blocks_count-1;
58		}
59
60		/*
61		 * Check to make sure the block bitmap for group is sane
62		 */
63		blk = fs->group_desc[i].bg_block_bitmap;
64		if (blk < first_block || blk > last_block ||
65		    ext2fs_test_block_bitmap(bmap, blk)) {
66			retval = EXT2_ET_GDESC_BAD_BLOCK_MAP;
67			goto errout;
68		}
69		ext2fs_mark_block_bitmap(bmap, blk);
70
71		/*
72		 * Check to make sure the inode bitmap for group is sane
73		 */
74		blk = fs->group_desc[i].bg_inode_bitmap;
75		if (blk < first_block || blk > last_block ||
76		    ext2fs_test_block_bitmap(bmap, blk)) {
77			retval = EXT2_ET_GDESC_BAD_INODE_MAP;
78			goto errout;
79		}
80		ext2fs_mark_block_bitmap(bmap, blk);
81
82		/*
83		 * Check to make sure the inode table for group is sane
84		 */
85		blk = fs->group_desc[i].bg_inode_table;
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_bitmap(bmap, b)) {
94				retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
95				goto errout;
96			}
97			ext2fs_mark_block_bitmap(bmap, b);
98		}
99	}
100errout:
101	ext2fs_free_block_bitmap(bmap);
102	return retval;
103}
104