OpenWrt – Blame information for rev 4

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4 office 1 /*
2 * Copyright (C) 2009-2013 Felix Fietkau <nbd@nbd.name>
3 * Copyright (C) 2009-2013 Gabor Juhos <juhosg@openwrt.org>
4 * Copyright (C) 2012 Jonas Gorski <jogo@openwrt.org>
5 * Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published
9 * by the Free Software Foundation.
10 *
11 */
12  
13 #define pr_fmt(fmt) "mtdsplit: " fmt
14  
15 #include <linux/export.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/magic.h>
19 #include <linux/mtd/mtd.h>
20 #include <linux/mtd/partitions.h>
21 #include <linux/byteorder/generic.h>
22  
23 #include "mtdsplit.h"
24  
25 #define UBI_EC_MAGIC 0x55424923 /* UBI# */
26  
27 struct squashfs_super_block {
28 __le32 s_magic;
29 __le32 pad0[9];
30 __le64 bytes_used;
31 };
32  
33 int mtd_get_squashfs_len(struct mtd_info *master,
34 size_t offset,
35 size_t *squashfs_len)
36 {
37 struct squashfs_super_block sb;
38 size_t retlen;
39 int err;
40  
41 err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
42 if (err || (retlen != sizeof(sb))) {
43 pr_alert("error occured while reading from \"%s\"\n",
44 master->name);
45 return -EIO;
46 }
47  
48 if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
49 pr_alert("no squashfs found in \"%s\"\n", master->name);
50 return -EINVAL;
51 }
52  
53 retlen = le64_to_cpu(sb.bytes_used);
54 if (retlen <= 0) {
55 pr_alert("squashfs is empty in \"%s\"\n", master->name);
56 return -ENODEV;
57 }
58  
59 if (offset + retlen > master->size) {
60 pr_alert("squashfs has invalid size in \"%s\"\n",
61 master->name);
62 return -EINVAL;
63 }
64  
65 *squashfs_len = retlen;
66 return 0;
67 }
68 EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);
69  
70 static ssize_t mtd_next_eb(struct mtd_info *mtd, size_t offset)
71 {
72 return mtd_rounddown_to_eb(offset, mtd) + mtd->erasesize;
73 }
74  
75 int mtd_check_rootfs_magic(struct mtd_info *mtd, size_t offset,
76 enum mtdsplit_part_type *type)
77 {
78 u32 magic;
79 size_t retlen;
80 int ret;
81  
82 ret = mtd_read(mtd, offset, sizeof(magic), &retlen,
83 (unsigned char *) &magic);
84 if (ret)
85 return ret;
86  
87 if (retlen != sizeof(magic))
88 return -EIO;
89  
90 if (le32_to_cpu(magic) == SQUASHFS_MAGIC) {
91 if (type)
92 *type = MTDSPLIT_PART_TYPE_SQUASHFS;
93 return 0;
94 } else if (magic == 0x19852003) {
95 if (type)
96 *type = MTDSPLIT_PART_TYPE_JFFS2;
97 return 0;
98 } else if (be32_to_cpu(magic) == UBI_EC_MAGIC) {
99 if (type)
100 *type = MTDSPLIT_PART_TYPE_UBI;
101 return 0;
102 }
103  
104 return -EINVAL;
105 }
106 EXPORT_SYMBOL_GPL(mtd_check_rootfs_magic);
107  
108 int mtd_find_rootfs_from(struct mtd_info *mtd,
109 size_t from,
110 size_t limit,
111 size_t *ret_offset,
112 enum mtdsplit_part_type *type)
113 {
114 size_t offset;
115 int err;
116  
117 for (offset = from; offset < limit;
118 offset = mtd_next_eb(mtd, offset)) {
119 err = mtd_check_rootfs_magic(mtd, offset, type);
120 if (err)
121 continue;
122  
123 *ret_offset = offset;
124 return 0;
125 }
126  
127 return -ENODEV;
128 }
129 EXPORT_SYMBOL_GPL(mtd_find_rootfs_from);
130