1 /*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2010
5 * Phillip Lougher <phillip@squashfs.org.uk>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2,
10 * or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 * xattr_id.c
22 */
23
24 /*
25 * This file implements code to map the 32-bit xattr id stored in the inode
26 * into the on disk location of the xattr data.
27 */
28
29 #include <linux/fs.h>
30 #include <linux/vfs.h>
31 #include <linux/slab.h>
32
33 #include "squashfs_fs.h"
34 #include "squashfs_fs_sb.h"
35 #include "squashfs.h"
36 #include "xattr.h"
37
38 /*
39 * Map xattr id using the xattr id look up table
40 */
squashfs_xattr_lookup(struct super_block * sb,unsigned int index,int * count,unsigned int * size,unsigned long long * xattr)41 int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
42 int *count, unsigned int *size, unsigned long long *xattr)
43 {
44 struct squashfs_sb_info *msblk = sb->s_fs_info;
45 int block = SQUASHFS_XATTR_BLOCK(index);
46 int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
47 u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
48 struct squashfs_xattr_id id;
49 int err;
50
51 err = squashfs_read_metadata(sb, &id, &start_block, &offset,
52 sizeof(id));
53 if (err < 0)
54 return err;
55
56 *xattr = le64_to_cpu(id.xattr);
57 *size = le32_to_cpu(id.size);
58 *count = le32_to_cpu(id.count);
59 return 0;
60 }
61
62
63 /*
64 * Read uncompressed xattr id lookup table indexes from disk into memory
65 */
squashfs_read_xattr_id_table(struct super_block * sb,u64 start,u64 * xattr_table_start,int * xattr_ids)66 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
67 u64 *xattr_table_start, int *xattr_ids)
68 {
69 unsigned int len;
70 struct squashfs_xattr_id_table *id_table;
71
72 id_table = squashfs_read_table(sb, start, sizeof(*id_table));
73 if (IS_ERR(id_table))
74 return (__le64 *) id_table;
75
76 *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
77 *xattr_ids = le32_to_cpu(id_table->xattr_ids);
78 kfree(id_table);
79
80 /* Sanity check values */
81
82 /* there is always at least one xattr id */
83 if (*xattr_ids == 0)
84 return ERR_PTR(-EINVAL);
85
86 /* xattr_table should be less than start */
87 if (*xattr_table_start >= start)
88 return ERR_PTR(-EINVAL);
89
90 len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
91
92 TRACE("In read_xattr_index_table, length %d\n", len);
93
94 return squashfs_read_table(sb, start + sizeof(*id_table), len);
95 }
96