1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/*
* Copyright (C) 2009-2013 Felix Fietkau <nbd@openwrt.org>
* Copyright (C) 2009-2013 Gabor Juhos <juhosg@openwrt.org>
* Copyright (C) 2012 Jonas Gorski <jogo@openwrt.org>
* Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) "mtdsplit: " fmt
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/magic.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/byteorder/generic.h>
#include "mtdsplit.h"
struct squashfs_super_block {
__le32 s_magic;
__le32 pad0[9];
__le64 bytes_used;
};
int mtd_get_squashfs_len(struct mtd_info *master,
size_t offset,
size_t *squashfs_len)
{
struct squashfs_super_block sb;
size_t retlen;
int err;
err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
if (err || (retlen != sizeof(sb))) {
pr_alert("error occured while reading from \"%s\"\n",
master->name);
return -EIO;
}
if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
pr_alert("no squashfs found in \"%s\"\n", master->name);
return -EINVAL;
}
retlen = le64_to_cpu(sb.bytes_used);
if (retlen <= 0) {
pr_alert("squashfs is empty in \"%s\"\n", master->name);
return -ENODEV;
}
if (offset + retlen > master->size) {
pr_alert("squashfs has invalid size in \"%s\"\n",
master->name);
return -EINVAL;
}
*squashfs_len = retlen;
return 0;
}
EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);
static ssize_t mtd_next_eb(struct mtd_info *mtd, size_t offset)
{
return mtd_rounddown_to_eb(offset, mtd) + mtd->erasesize;
}
int mtd_check_rootfs_magic(struct mtd_info *mtd, size_t offset)
{
u32 magic;
size_t retlen;
int ret;
ret = mtd_read(mtd, offset, sizeof(magic), &retlen,
(unsigned char *) &magic);
if (ret)
return ret;
if (retlen != sizeof(magic))
return -EIO;
if (le32_to_cpu(magic) != SQUASHFS_MAGIC &&
magic != 0x19852003)
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(mtd_check_rootfs_magic);
int mtd_find_rootfs_from(struct mtd_info *mtd,
size_t from,
size_t limit,
size_t *ret_offset)
{
size_t offset;
int err;
for (offset = from; offset < limit;
offset = mtd_next_eb(mtd, offset)) {
err = mtd_check_rootfs_magic(mtd, offset);
if (err)
continue;
*ret_offset = offset;
return 0;
}
return -ENODEV;
}
EXPORT_SYMBOL_GPL(mtd_find_rootfs_from);
|
