mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-22 17:01:14 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
180 lines
3.8 KiB
C
180 lines
3.8 KiB
C
/*
|
|
* symlink.c - operations for sysfs symlinks.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kobject.h>
|
|
#include <linux/namei.h>
|
|
|
|
#include "sysfs.h"
|
|
|
|
static int object_depth(struct kobject * kobj)
|
|
{
|
|
struct kobject * p = kobj;
|
|
int depth = 0;
|
|
do { depth++; } while ((p = p->parent));
|
|
return depth;
|
|
}
|
|
|
|
static int object_path_length(struct kobject * kobj)
|
|
{
|
|
struct kobject * p = kobj;
|
|
int length = 1;
|
|
do {
|
|
length += strlen(kobject_name(p)) + 1;
|
|
p = p->parent;
|
|
} while (p);
|
|
return length;
|
|
}
|
|
|
|
static void fill_object_path(struct kobject * kobj, char * buffer, int length)
|
|
{
|
|
struct kobject * p;
|
|
|
|
--length;
|
|
for (p = kobj; p; p = p->parent) {
|
|
int cur = strlen(kobject_name(p));
|
|
|
|
/* back up enough to print this bus id with '/' */
|
|
length -= cur;
|
|
strncpy(buffer + length,kobject_name(p),cur);
|
|
*(buffer + --length) = '/';
|
|
}
|
|
}
|
|
|
|
static int sysfs_add_link(struct dentry * parent, char * name, struct kobject * target)
|
|
{
|
|
struct sysfs_dirent * parent_sd = parent->d_fsdata;
|
|
struct sysfs_symlink * sl;
|
|
int error = 0;
|
|
|
|
error = -ENOMEM;
|
|
sl = kmalloc(sizeof(*sl), GFP_KERNEL);
|
|
if (!sl)
|
|
goto exit1;
|
|
|
|
sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
|
|
if (!sl->link_name)
|
|
goto exit2;
|
|
|
|
strcpy(sl->link_name, name);
|
|
sl->target_kobj = kobject_get(target);
|
|
|
|
error = sysfs_make_dirent(parent_sd, NULL, sl, S_IFLNK|S_IRWXUGO,
|
|
SYSFS_KOBJ_LINK);
|
|
if (!error)
|
|
return 0;
|
|
|
|
kfree(sl->link_name);
|
|
exit2:
|
|
kfree(sl);
|
|
exit1:
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* sysfs_create_link - create symlink between two objects.
|
|
* @kobj: object whose directory we're creating the link in.
|
|
* @target: object we're pointing to.
|
|
* @name: name of the symlink.
|
|
*/
|
|
int sysfs_create_link(struct kobject * kobj, struct kobject * target, char * name)
|
|
{
|
|
struct dentry * dentry = kobj->dentry;
|
|
int error = 0;
|
|
|
|
BUG_ON(!kobj || !kobj->dentry || !name);
|
|
|
|
down(&dentry->d_inode->i_sem);
|
|
error = sysfs_add_link(dentry, name, target);
|
|
up(&dentry->d_inode->i_sem);
|
|
return error;
|
|
}
|
|
|
|
|
|
/**
|
|
* sysfs_remove_link - remove symlink in object's directory.
|
|
* @kobj: object we're acting for.
|
|
* @name: name of the symlink to remove.
|
|
*/
|
|
|
|
void sysfs_remove_link(struct kobject * kobj, char * name)
|
|
{
|
|
sysfs_hash_and_remove(kobj->dentry,name);
|
|
}
|
|
|
|
static int sysfs_get_target_path(struct kobject * kobj, struct kobject * target,
|
|
char *path)
|
|
{
|
|
char * s;
|
|
int depth, size;
|
|
|
|
depth = object_depth(kobj);
|
|
size = object_path_length(target) + depth * 3 - 1;
|
|
if (size > PATH_MAX)
|
|
return -ENAMETOOLONG;
|
|
|
|
pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
|
|
|
|
for (s = path; depth--; s += 3)
|
|
strcpy(s,"../");
|
|
|
|
fill_object_path(target, path, size);
|
|
pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int sysfs_getlink(struct dentry *dentry, char * path)
|
|
{
|
|
struct kobject *kobj, *target_kobj;
|
|
int error = 0;
|
|
|
|
kobj = sysfs_get_kobject(dentry->d_parent);
|
|
if (!kobj)
|
|
return -EINVAL;
|
|
|
|
target_kobj = sysfs_get_kobject(dentry);
|
|
if (!target_kobj) {
|
|
kobject_put(kobj);
|
|
return -EINVAL;
|
|
}
|
|
|
|
down_read(&sysfs_rename_sem);
|
|
error = sysfs_get_target_path(kobj, target_kobj, path);
|
|
up_read(&sysfs_rename_sem);
|
|
|
|
kobject_put(kobj);
|
|
kobject_put(target_kobj);
|
|
return error;
|
|
|
|
}
|
|
|
|
static int sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
|
|
{
|
|
int error = -ENOMEM;
|
|
unsigned long page = get_zeroed_page(GFP_KERNEL);
|
|
if (page)
|
|
error = sysfs_getlink(dentry, (char *) page);
|
|
nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
|
|
return 0;
|
|
}
|
|
|
|
static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd)
|
|
{
|
|
char *page = nd_get_link(nd);
|
|
if (!IS_ERR(page))
|
|
free_page((unsigned long)page);
|
|
}
|
|
|
|
struct inode_operations sysfs_symlink_inode_operations = {
|
|
.readlink = generic_readlink,
|
|
.follow_link = sysfs_follow_link,
|
|
.put_link = sysfs_put_link,
|
|
};
|
|
|
|
|
|
EXPORT_SYMBOL_GPL(sysfs_create_link);
|
|
EXPORT_SYMBOL_GPL(sysfs_remove_link);
|
|
|