[821] | 1 | /*
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| 2 | * check_desc.c --- Check the group descriptors of an ext2 filesystem
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| 3 | *
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| 4 | * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
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| 5 | *
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| 6 | * %Begin-Header%
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| 7 | * This file may be redistributed under the terms of the GNU Public
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| 8 | * License.
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| 9 | * %End-Header%
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| 10 | */
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| 11 |
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| 12 | #include <stdio.h>
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| 13 | #include <string.h>
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| 14 | #if HAVE_UNISTD_H
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| 15 | #include <unistd.h>
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| 16 | #endif
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| 17 | #include <fcntl.h>
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| 18 | #include <time.h>
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| 19 | #if HAVE_SYS_STAT_H
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| 20 | #include <sys/stat.h>
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| 21 | #endif
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| 22 | #if HAVE_SYS_TYPES_H
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| 23 | #include <sys/types.h>
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| 24 | #endif
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| 25 |
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| 26 | #include "ext2_fs.h"
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| 27 | #include "ext2fs.h"
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| 28 |
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| 29 | /*
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| 30 | * This routine sanity checks the group descriptors
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| 31 | */
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| 32 | errcode_t ext2fs_check_desc(ext2_filsys fs)
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| 33 | {
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| 34 | dgrp_t i;
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| 35 | blk_t block = fs->super->s_first_data_block;
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| 36 | blk_t next;
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| 37 |
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| 38 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 39 |
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| 40 | for (i = 0; i < fs->group_desc_count; i++) {
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| 41 | next = block + fs->super->s_blocks_per_group;
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| 42 | /*
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| 43 | * Check to make sure block bitmap for group is
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| 44 | * located within the group.
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| 45 | */
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| 46 | if (fs->group_desc[i].bg_block_bitmap < block ||
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| 47 | fs->group_desc[i].bg_block_bitmap >= next)
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| 48 | return EXT2_ET_GDESC_BAD_BLOCK_MAP;
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| 49 | /*
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| 50 | * Check to make sure inode bitmap for group is
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| 51 | * located within the group
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| 52 | */
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| 53 | if (fs->group_desc[i].bg_inode_bitmap < block ||
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| 54 | fs->group_desc[i].bg_inode_bitmap >= next)
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| 55 | return EXT2_ET_GDESC_BAD_INODE_MAP;
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| 56 | /*
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| 57 | * Check to make sure inode table for group is located
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| 58 | * within the group
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| 59 | */
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| 60 | if (fs->group_desc[i].bg_inode_table < block ||
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| 61 | ((fs->group_desc[i].bg_inode_table +
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| 62 | fs->inode_blocks_per_group) >= next))
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| 63 | return EXT2_ET_GDESC_BAD_INODE_TABLE;
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| 64 |
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| 65 | block = next;
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| 66 | }
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| 67 | return 0;
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| 68 | }
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