5113f6f70
 김현기
kernel add
|
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
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* fs/kernfs/symlink.c - kernfs symlink implementation
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
*
* This file is released under the GPLv2.
*/
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/namei.h>
#include "kernfs-internal.h"
/**
* kernfs_create_link - create a symlink
* @parent: directory to create the symlink in
* @name: name of the symlink
* @target: target node for the symlink to point to
*
* Returns the created node on success, ERR_PTR() value on error.
*/
struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
const char *name,
struct kernfs_node *target)
{
struct kernfs_node *kn;
int error;
kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK);
if (!kn)
return ERR_PTR(-ENOMEM);
if (kernfs_ns_enabled(parent))
kn->ns = target->ns;
kn->symlink.target_kn = target;
kernfs_get(target); /* ref owned by symlink */
error = kernfs_add_one(kn);
if (!error)
return kn;
kernfs_put(kn);
return ERR_PTR(error);
}
static int kernfs_get_target_path(struct kernfs_node *parent,
struct kernfs_node *target, char *path)
{
struct kernfs_node *base, *kn;
char *s = path;
int len = 0;
/* go up to the root, stop at the base */
base = parent;
while (base->parent) {
kn = target->parent;
while (kn->parent && base != kn)
kn = kn->parent;
if (base == kn)
break;
strcpy(s, "../");
s += 3;
base = base->parent;
}
/* determine end of target string for reverse fillup */
kn = target;
while (kn->parent && kn != base) {
len += strlen(kn->name) + 1;
kn = kn->parent;
}
/* check limits */
if (len < 2)
return -EINVAL;
len--;
if ((s - path) + len > PATH_MAX)
return -ENAMETOOLONG;
/* reverse fillup of target string from target to base */
kn = target;
while (kn->parent && kn != base) {
int slen = strlen(kn->name);
len -= slen;
strncpy(s + len, kn->name, slen);
if (len)
s[--len] = '/';
kn = kn->parent;
}
return 0;
}
static int kernfs_getlink(struct dentry *dentry, char *path)
{
struct kernfs_node *kn = dentry->d_fsdata;
struct kernfs_node *parent = kn->parent;
struct kernfs_node *target = kn->symlink.target_kn;
int error;
mutex_lock(&kernfs_mutex);
error = kernfs_get_target_path(parent, target, path);
mutex_unlock(&kernfs_mutex);
return error;
}
static const char *kernfs_iop_follow_link(struct dentry *dentry, void **cookie)
{
int error = -ENOMEM;
unsigned long page = get_zeroed_page(GFP_KERNEL);
if (!page)
return ERR_PTR(-ENOMEM);
error = kernfs_getlink(dentry, (char *)page);
if (unlikely(error < 0)) {
free_page((unsigned long)page);
return ERR_PTR(error);
}
return *cookie = (char *)page;
}
const struct inode_operations kernfs_symlink_iops = {
.setxattr = kernfs_iop_setxattr,
.removexattr = kernfs_iop_removexattr,
.getxattr = kernfs_iop_getxattr,
.listxattr = kernfs_iop_listxattr,
.readlink = generic_readlink,
.follow_link = kernfs_iop_follow_link,
.put_link = free_page_put_link,
.setattr = kernfs_iop_setattr,
.getattr = kernfs_iop_getattr,
.permission = kernfs_iop_permission,
};
|