source: src/linux/universal/linux-4.9/fs/squashfs/xattr_id.c @ 31630

Last change on this file since 31630 was 31630, checked in by brainslayer, 2 weeks ago

new fs is compatible with standard squashfs, just smaller

File size: 2.7 KB
Line 
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}
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