linux/fs/proc/self.c
Eric W. Biederman e656d8a6f7 procfs: Use the proc generic infrastructure for proc/self.
I had visions at one point of splitting proc into two filesystems.  If
that had happened proc/self being the the part of proc that actually deals
with pids would have been a nice cleanup.  As it is proc/self requires
a lot of unnecessary infrastructure for a single file.

The only user visible change is that a mounted /proc for a pid namespace
that is dead now shows a broken proc symlink, instead of being completely
invisible.  I don't think anyone will notice or care.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-19 03:09:34 -08:00

60 lines
1.4 KiB
C

#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
/*
* /proc/self:
*/
static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
int buflen)
{
struct pid_namespace *ns = dentry->d_sb->s_fs_info;
pid_t tgid = task_tgid_nr_ns(current, ns);
char tmp[PROC_NUMBUF];
if (!tgid)
return -ENOENT;
sprintf(tmp, "%d", tgid);
return vfs_readlink(dentry,buffer,buflen,tmp);
}
static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct pid_namespace *ns = dentry->d_sb->s_fs_info;
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name = ERR_PTR(-ENOENT);
if (tgid) {
/* 11 for max length of signed int in decimal + NULL term */
name = kmalloc(12, GFP_KERNEL);
if (!name)
name = ERR_PTR(-ENOMEM);
else
sprintf(name, "%d", tgid);
}
nd_set_link(nd, name);
return NULL;
}
static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
void *cookie)
{
char *s = nd_get_link(nd);
if (!IS_ERR(s))
kfree(s);
}
static const struct inode_operations proc_self_inode_operations = {
.readlink = proc_self_readlink,
.follow_link = proc_self_follow_link,
.put_link = proc_self_put_link,
};
void __init proc_self_init(void)
{
struct proc_dir_entry *proc_self_symlink;
mode_t mode;
mode = S_IFLNK | S_IRWXUGO;
proc_self_symlink = proc_create("self", mode, NULL, NULL );
proc_self_symlink->proc_iops = &proc_self_inode_operations;
}