1 /* -*- linux-c -*- --------------------------------------------------------- *
3 * linux/fs/devpts/inode.c
5 * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
7 * This file is part of the Linux kernel and is made available under
8 * the terms of the GNU General Public License, version 2, or at your
9 * option, any later version, incorporated herein by reference.
11 * ------------------------------------------------------------------------- */
13 #include <linux/module.h>
14 #include <linux/init.h>
16 #include <linux/sched.h>
17 #include <linux/namei.h>
18 #include <linux/mount.h>
19 #include <linux/tty.h>
20 #include <linux/mutex.h>
21 #include <linux/idr.h>
22 #include <linux/devpts_fs.h>
23 #include <linux/parser.h>
24 #include <linux/fsnotify.h>
25 #include <linux/seq_file.h>
27 #define DEVPTS_SUPER_MAGIC 0x1cd1
29 #define DEVPTS_DEFAULT_MODE 0600
32 extern int pty_limit; /* Config limit on Unix98 ptys */
33 static DEFINE_IDA(allocated_ptys);
34 static DEFINE_MUTEX(allocated_ptys_lock);
36 static struct vfsmount *devpts_mnt;
37 static struct dentry *devpts_root;
45 } config = {.mode = DEVPTS_DEFAULT_MODE};
48 Opt_uid, Opt_gid, Opt_mode,
52 static match_table_t tokens = {
55 {Opt_mode, "mode=%o"},
59 static int devpts_remount(struct super_block *sb, int *flags, char *data)
67 config.mode = DEVPTS_DEFAULT_MODE;
69 while ((p = strsep(&data, ",")) != NULL) {
70 substring_t args[MAX_OPT_ARGS];
77 token = match_token(p, tokens, args);
80 if (match_int(&args[0], &option))
86 if (match_int(&args[0], &option))
92 if (match_octal(&args[0], &option))
94 config.mode = option & S_IALLUGO;
97 printk(KERN_ERR "devpts: called with bogus options\n");
105 static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
108 seq_printf(seq, ",uid=%u", config.uid);
110 seq_printf(seq, ",gid=%u", config.gid);
111 seq_printf(seq, ",mode=%03o", config.mode);
116 static const struct super_operations devpts_sops = {
117 .statfs = simple_statfs,
118 .remount_fs = devpts_remount,
119 .show_options = devpts_show_options,
123 devpts_fill_super(struct super_block *s, void *data, int silent)
125 struct inode * inode;
127 s->s_blocksize = 1024;
128 s->s_blocksize_bits = 10;
129 s->s_magic = DEVPTS_SUPER_MAGIC;
130 s->s_op = &devpts_sops;
133 inode = new_inode(s);
137 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
139 inode->i_uid = inode->i_gid = 0;
140 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
141 inode->i_op = &simple_dir_inode_operations;
142 inode->i_fop = &simple_dir_operations;
145 devpts_root = s->s_root = d_alloc_root(inode);
149 printk("devpts: get root dentry failed\n");
155 static int devpts_get_sb(struct file_system_type *fs_type,
156 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
158 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
161 static struct file_system_type devpts_fs_type = {
162 .owner = THIS_MODULE,
164 .get_sb = devpts_get_sb,
165 .kill_sb = kill_anon_super,
169 * The normal naming convention is simply /dev/pts/<number>; this conforms
170 * to the System V naming convention
173 static struct dentry *get_node(int num)
176 struct dentry *root = devpts_root;
177 mutex_lock(&root->d_inode->i_mutex);
178 return lookup_one_len(s, root, sprintf(s, "%d", num));
181 int devpts_new_index(struct inode *ptmx_inode)
187 if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
191 mutex_lock(&allocated_ptys_lock);
192 ida_ret = ida_get_new(&allocated_ptys, &index);
194 mutex_unlock(&allocated_ptys_lock);
195 if (ida_ret == -EAGAIN)
200 if (index >= pty_limit) {
201 ida_remove(&allocated_ptys, index);
202 mutex_unlock(&allocated_ptys_lock);
205 mutex_unlock(&allocated_ptys_lock);
209 void devpts_kill_index(struct inode *ptmx_inode, int idx)
211 mutex_lock(&allocated_ptys_lock);
212 ida_remove(&allocated_ptys, idx);
213 mutex_unlock(&allocated_ptys_lock);
216 int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
218 int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
219 struct tty_driver *driver = tty->driver;
220 dev_t device = MKDEV(driver->major, driver->minor_start+number);
221 struct dentry *dentry;
222 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
224 /* We're supposed to be given the slave end of a pty */
225 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
226 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
231 inode->i_ino = number+2;
232 inode->i_uid = config.setuid ? config.uid : current->fsuid;
233 inode->i_gid = config.setgid ? config.gid : current->fsgid;
234 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
235 init_special_inode(inode, S_IFCHR|config.mode, device);
236 inode->i_private = tty;
238 dentry = get_node(number);
239 if (!IS_ERR(dentry) && !dentry->d_inode) {
240 d_instantiate(dentry, inode);
241 fsnotify_create(devpts_root->d_inode, dentry);
244 mutex_unlock(&devpts_root->d_inode->i_mutex);
249 struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
251 BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
253 if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
254 return (struct tty_struct *)pts_inode->i_private;
258 void devpts_pty_kill(struct tty_struct *tty)
260 int number = tty->index;
261 struct dentry *dentry = get_node(number);
263 if (!IS_ERR(dentry)) {
264 struct inode *inode = dentry->d_inode;
272 mutex_unlock(&devpts_root->d_inode->i_mutex);
275 static int __init init_devpts_fs(void)
277 int err = register_filesystem(&devpts_fs_type);
279 devpts_mnt = kern_mount(&devpts_fs_type);
280 if (IS_ERR(devpts_mnt))
281 err = PTR_ERR(devpts_mnt);
286 static void __exit exit_devpts_fs(void)
288 unregister_filesystem(&devpts_fs_type);
292 module_init(init_devpts_fs)
293 module_exit(exit_devpts_fs)
294 MODULE_LICENSE("GPL");