1 /*
2 * volume_id - reads filesystem label and uuid
3 *
4 * Copyright (C) 2012 S-G Bergh <sgb@systemasis.org>
5 *
6 * Licensed under GPLv2, see file LICENSE in this source tree.
7 */
8 //config:config FEATURE_VOLUMEID_SQUASHFS
9 //config: bool "SquashFS filesystem"
10 //config: default y
11 //config: depends on VOLUMEID && FEATURE_BLKID_TYPE
12 //config: help
13 //config: Squashfs is a compressed read-only filesystem for Linux. Squashfs is
14 //config: intended for general read-only filesystem use and in constrained block
15 //config: device/memory systems (e.g. embedded systems) where low overhead is
16 //config: needed.
17
18 //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_SQUASHFS) += squashfs.o
19
20 #include "volume_id_internal.h"
21
22 struct squashfs_superblock {
23 uint32_t magic;
24 /*
25 uint32_t dummy[6];
26 uint16_t major;
27 uint16_t minor;
28 */
29 } PACKED;
30
volume_id_probe_squashfs(struct volume_id * id)31 int FAST_FUNC volume_id_probe_squashfs(struct volume_id *id /*,uint64_t off*/)
32 {
33 #define off ((uint64_t)0)
34 struct squashfs_superblock *sb;
35
36 dbg("SquashFS: probing at offset 0x%llx", (unsigned long long) off);
37 sb = volume_id_get_buffer(id, off, 0x200);
38 if (!sb)
39 return -1;
40
41 // Old SquashFS (pre 4.0) can be both big and little endian, so test for both.
42 // Likewise, it is commonly used in firwmare with some non-standard signatures.
43 #define pack(a,b,c,d) ( (uint32_t)((a * 256 + b) * 256 + c) * 256 + d )
44 #define SIG1 pack('s','q','s','h')
45 #define SIG2 pack('h','s','q','s')
46 #define SIG3 pack('s','h','s','q')
47 #define SIG4 pack('q','s','h','s')
48 if (sb->magic == SIG1
49 || sb->magic == SIG2
50 || sb->magic == SIG3
51 || sb->magic == SIG4
52 ) {
53 IF_FEATURE_BLKID_TYPE(id->type = "squashfs";)
54 return 0;
55 }
56
57 return -1;
58 }
59