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      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 }
    105