source: MondoRescue/branches/stable/mindi-busybox/e2fsprogs/ext2fs/check_desc.c@ 821

/*
 * check_desc.c --- Check the group descriptors of an ext2 filesystem
 *
 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"

/*
 * This routine sanity checks the group descriptors
 */
errcode_t ext2fs_check_desc(ext2_filsys fs)
{
    dgrp_t i;
    blk_t block = fs->super->s_first_data_block;
    blk_t next;

    EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

    for (i = 0; i < fs->group_desc_count; i++) {
        next = block + fs->super->s_blocks_per_group;
        /*
         * Check to make sure block bitmap for group is
         * located within the group.
         */
        if (fs->group_desc[i].bg_block_bitmap < block ||
            fs->group_desc[i].bg_block_bitmap >= next)
            return EXT2_ET_GDESC_BAD_BLOCK_MAP;
        /*
         * Check to make sure inode bitmap for group is
         * located within the group
         */
        if (fs->group_desc[i].bg_inode_bitmap < block ||
            fs->group_desc[i].bg_inode_bitmap >= next)
            return EXT2_ET_GDESC_BAD_INODE_MAP;
        /*
         * Check to make sure inode table for group is located
         * within the group
         */
        if (fs->group_desc[i].bg_inode_table < block ||
            ((fs->group_desc[i].bg_inode_table +
              fs->inode_blocks_per_group) >= next))
            return EXT2_ET_GDESC_BAD_INODE_TABLE;

        block = next;
    }
    return 0;
}