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Phillip Lougher4b5397d2010-05-14 20:48:47 +01001/*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2010
5 * Phillip Lougher <phillip@lougher.demon.co.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_fs_i.h"
36#include "squashfs.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,
Stephen Hemmingeraa5b1892010-05-13 16:32:21 -070042 int *count, unsigned int *size, unsigned long long *xattr)
Phillip Lougher4b5397d2010-05-14 20:48:47 +010043{
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 __le64 *xid_table;
71 struct squashfs_xattr_id_table id_table;
72 int err;
73
74 err = squashfs_read_table(sb, &id_table, start, sizeof(id_table));
75 if (err < 0) {
76 ERROR("unable to read xattr id table\n");
77 return ERR_PTR(err);
78 }
79 *xattr_table_start = le64_to_cpu(id_table.xattr_table_start);
80 *xattr_ids = le32_to_cpu(id_table.xattr_ids);
81 len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
82
83 TRACE("In read_xattr_index_table, length %d\n", len);
84
85 /* Allocate xattr id lookup table indexes */
86 xid_table = kmalloc(len, GFP_KERNEL);
87 if (xid_table == NULL) {
88 ERROR("Failed to allocate xattr id index table\n");
89 return ERR_PTR(-ENOMEM);
90 }
91
92 err = squashfs_read_table(sb, xid_table, start + sizeof(id_table), len);
93 if (err < 0) {
94 ERROR("unable to read xattr id index table\n");
95 kfree(xid_table);
96 return ERR_PTR(err);
97 }
98
99 return xid_table;
100}