LXR linux/fs/proc/self.c

   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}
  60