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 */
41int 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 */
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