Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * symlink.c - operations for sysfs symlinks. | |
3 | */ | |
4 | ||
5 | #include <linux/fs.h> | |
ceeee1fb | 6 | #include <linux/mount.h> |
1da177e4 LT |
7 | #include <linux/module.h> |
8 | #include <linux/kobject.h> | |
9 | #include <linux/namei.h> | |
94bebf4d | 10 | #include <asm/semaphore.h> |
1da177e4 LT |
11 | |
12 | #include "sysfs.h" | |
13 | ||
14 | static int object_depth(struct kobject * kobj) | |
15 | { | |
16 | struct kobject * p = kobj; | |
17 | int depth = 0; | |
18 | do { depth++; } while ((p = p->parent)); | |
19 | return depth; | |
20 | } | |
21 | ||
22 | static int object_path_length(struct kobject * kobj) | |
23 | { | |
24 | struct kobject * p = kobj; | |
25 | int length = 1; | |
26 | do { | |
27 | length += strlen(kobject_name(p)) + 1; | |
28 | p = p->parent; | |
29 | } while (p); | |
30 | return length; | |
31 | } | |
32 | ||
33 | static void fill_object_path(struct kobject * kobj, char * buffer, int length) | |
34 | { | |
35 | struct kobject * p; | |
36 | ||
37 | --length; | |
38 | for (p = kobj; p; p = p->parent) { | |
39 | int cur = strlen(kobject_name(p)); | |
40 | ||
41 | /* back up enough to print this bus id with '/' */ | |
42 | length -= cur; | |
43 | strncpy(buffer + length,kobject_name(p),cur); | |
44 | *(buffer + --length) = '/'; | |
45 | } | |
46 | } | |
47 | ||
e3a15db2 | 48 | static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target) |
1da177e4 LT |
49 | { |
50 | struct sysfs_dirent * parent_sd = parent->d_fsdata; | |
51 | struct sysfs_symlink * sl; | |
52 | int error = 0; | |
53 | ||
54 | error = -ENOMEM; | |
55 | sl = kmalloc(sizeof(*sl), GFP_KERNEL); | |
56 | if (!sl) | |
57 | goto exit1; | |
58 | ||
59 | sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL); | |
60 | if (!sl->link_name) | |
61 | goto exit2; | |
62 | ||
63 | strcpy(sl->link_name, name); | |
64 | sl->target_kobj = kobject_get(target); | |
65 | ||
66 | error = sysfs_make_dirent(parent_sd, NULL, sl, S_IFLNK|S_IRWXUGO, | |
67 | SYSFS_KOBJ_LINK); | |
68 | if (!error) | |
69 | return 0; | |
70 | ||
b3229087 | 71 | kobject_put(target); |
1da177e4 LT |
72 | kfree(sl->link_name); |
73 | exit2: | |
74 | kfree(sl); | |
75 | exit1: | |
76 | return error; | |
77 | } | |
78 | ||
79 | /** | |
80 | * sysfs_create_link - create symlink between two objects. | |
81 | * @kobj: object whose directory we're creating the link in. | |
82 | * @target: object we're pointing to. | |
83 | * @name: name of the symlink. | |
84 | */ | |
e3a15db2 | 85 | int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name) |
1da177e4 | 86 | { |
ceeee1fb | 87 | struct dentry *dentry = NULL; |
c516865c | 88 | int error = -EEXIST; |
1da177e4 | 89 | |
ceeee1fb GKH |
90 | BUG_ON(!name); |
91 | ||
92 | if (!kobj) { | |
93 | if (sysfs_mount && sysfs_mount->mnt_sb) | |
94 | dentry = sysfs_mount->mnt_sb->s_root; | |
95 | } else | |
96 | dentry = kobj->dentry; | |
97 | ||
98 | if (!dentry) | |
99 | return -EFAULT; | |
1da177e4 | 100 | |
1b1dcc1b | 101 | mutex_lock(&dentry->d_inode->i_mutex); |
c516865c MS |
102 | if (!sysfs_dirent_exist(dentry->d_fsdata, name)) |
103 | error = sysfs_add_link(dentry, name, target); | |
1b1dcc1b | 104 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
105 | return error; |
106 | } | |
107 | ||
108 | ||
109 | /** | |
110 | * sysfs_remove_link - remove symlink in object's directory. | |
111 | * @kobj: object we're acting for. | |
112 | * @name: name of the symlink to remove. | |
113 | */ | |
114 | ||
e3a15db2 | 115 | void sysfs_remove_link(struct kobject * kobj, const char * name) |
1da177e4 LT |
116 | { |
117 | sysfs_hash_and_remove(kobj->dentry,name); | |
118 | } | |
119 | ||
120 | static int sysfs_get_target_path(struct kobject * kobj, struct kobject * target, | |
e3a15db2 | 121 | char *path) |
1da177e4 LT |
122 | { |
123 | char * s; | |
124 | int depth, size; | |
125 | ||
126 | depth = object_depth(kobj); | |
127 | size = object_path_length(target) + depth * 3 - 1; | |
128 | if (size > PATH_MAX) | |
129 | return -ENAMETOOLONG; | |
130 | ||
131 | pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size); | |
132 | ||
133 | for (s = path; depth--; s += 3) | |
134 | strcpy(s,"../"); | |
135 | ||
136 | fill_object_path(target, path, size); | |
137 | pr_debug("%s: path = '%s'\n", __FUNCTION__, path); | |
138 | ||
139 | return 0; | |
140 | } | |
141 | ||
142 | static int sysfs_getlink(struct dentry *dentry, char * path) | |
143 | { | |
144 | struct kobject *kobj, *target_kobj; | |
145 | int error = 0; | |
146 | ||
147 | kobj = sysfs_get_kobject(dentry->d_parent); | |
148 | if (!kobj) | |
149 | return -EINVAL; | |
150 | ||
151 | target_kobj = sysfs_get_kobject(dentry); | |
152 | if (!target_kobj) { | |
153 | kobject_put(kobj); | |
154 | return -EINVAL; | |
155 | } | |
156 | ||
157 | down_read(&sysfs_rename_sem); | |
158 | error = sysfs_get_target_path(kobj, target_kobj, path); | |
159 | up_read(&sysfs_rename_sem); | |
160 | ||
161 | kobject_put(kobj); | |
162 | kobject_put(target_kobj); | |
163 | return error; | |
164 | ||
165 | } | |
166 | ||
cc314eef | 167 | static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd) |
1da177e4 LT |
168 | { |
169 | int error = -ENOMEM; | |
170 | unsigned long page = get_zeroed_page(GFP_KERNEL); | |
171 | if (page) | |
172 | error = sysfs_getlink(dentry, (char *) page); | |
173 | nd_set_link(nd, error ? ERR_PTR(error) : (char *)page); | |
cc314eef | 174 | return NULL; |
1da177e4 LT |
175 | } |
176 | ||
cc314eef | 177 | static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 LT |
178 | { |
179 | char *page = nd_get_link(nd); | |
180 | if (!IS_ERR(page)) | |
181 | free_page((unsigned long)page); | |
182 | } | |
183 | ||
c5ef1c42 | 184 | const struct inode_operations sysfs_symlink_inode_operations = { |
1da177e4 LT |
185 | .readlink = generic_readlink, |
186 | .follow_link = sysfs_follow_link, | |
187 | .put_link = sysfs_put_link, | |
188 | }; | |
189 | ||
190 | ||
191 | EXPORT_SYMBOL_GPL(sysfs_create_link); | |
192 | EXPORT_SYMBOL_GPL(sysfs_remove_link); |