tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <linux/proc_fs.h>
2#include <linux/sched.h>
3#include <linux/namei.h>
4
5/*
6 * /proc/self:
7 */
8static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
9 int buflen)
10{
11 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
12 pid_t tgid = task_tgid_nr_ns(current, ns);
13 char tmp[PROC_NUMBUF];
14 if (!tgid)
15 return -ENOENT;
16 sprintf(tmp, "%d", tgid);
17 return vfs_readlink(dentry,buffer,buflen,tmp);
18}
19
20static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
21{
22 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
23 pid_t tgid = task_tgid_nr_ns(current, ns);
24 char *name = ERR_PTR(-ENOENT);
25 if (tgid) {
26 /* 11 for max length of signed int in decimal + NULL term */
27 name = kmalloc(12, GFP_KERNEL);
28 if (!name)
29 name = ERR_PTR(-ENOMEM);
30 else
31 sprintf(name, "%d", tgid);
32 }
33 nd_set_link(nd, name);
34 return NULL;
35}
36
37static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
38 void *cookie)
39{
40 char *s = nd_get_link(nd);
41 if (!IS_ERR(s))
42 kfree(s);
43}
44
45static const struct inode_operations proc_self_inode_operations = {
46 .readlink = proc_self_readlink,
47 .follow_link = proc_self_follow_link,
48 .put_link = proc_self_put_link,
49};
50
51void __init proc_self_init(void)
52{
53 struct proc_dir_entry *proc_self_symlink;
54 mode_t mode;
55
56 mode = S_IFLNK | S_IRWXUGO;
57 proc_self_symlink = proc_create("self", mode, NULL, NULL );
58 proc_self_symlink->proc_iops = &proc_self_inode_operations;
59}