devpts: add fsnotify create event
[linux-2.6.git] / fs / devpts / inode.c
1 /* -*- linux-c -*- --------------------------------------------------------- *
2  *
3  * linux/fs/devpts/inode.c
4  *
5  *  Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
6  *
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.
10  *
11  * ------------------------------------------------------------------------- */
12
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/fs.h>
16 #include <linux/sched.h>
17 #include <linux/namei.h>
18 #include <linux/mount.h>
19 #include <linux/tty.h>
20 #include <linux/devpts_fs.h>
21 #include <linux/parser.h>
22 #include <linux/fsnotify.h>
23
24 #define DEVPTS_SUPER_MAGIC 0x1cd1
25
26 static struct vfsmount *devpts_mnt;
27 static struct dentry *devpts_root;
28
29 static struct {
30         int setuid;
31         int setgid;
32         uid_t   uid;
33         gid_t   gid;
34         umode_t mode;
35 } config = {.mode = 0600};
36
37 enum {
38         Opt_uid, Opt_gid, Opt_mode,
39         Opt_err
40 };
41
42 static match_table_t tokens = {
43         {Opt_uid, "uid=%u"},
44         {Opt_gid, "gid=%u"},
45         {Opt_mode, "mode=%o"},
46         {Opt_err, NULL}
47 };
48
49 static int devpts_remount(struct super_block *sb, int *flags, char *data)
50 {
51         char *p;
52
53         config.setuid  = 0;
54         config.setgid  = 0;
55         config.uid     = 0;
56         config.gid     = 0;
57         config.mode    = 0600;
58
59         while ((p = strsep(&data, ",")) != NULL) {
60                 substring_t args[MAX_OPT_ARGS];
61                 int token;
62                 int option;
63
64                 if (!*p)
65                         continue;
66
67                 token = match_token(p, tokens, args);
68                 switch (token) {
69                 case Opt_uid:
70                         if (match_int(&args[0], &option))
71                                 return -EINVAL;
72                         config.uid = option;
73                         config.setuid = 1;
74                         break;
75                 case Opt_gid:
76                         if (match_int(&args[0], &option))
77                                 return -EINVAL;
78                         config.gid = option;
79                         config.setgid = 1;
80                         break;
81                 case Opt_mode:
82                         if (match_octal(&args[0], &option))
83                                 return -EINVAL;
84                         config.mode = option & ~S_IFMT;
85                         break;
86                 default:
87                         printk(KERN_ERR "devpts: called with bogus options\n");
88                         return -EINVAL;
89                 }
90         }
91
92         return 0;
93 }
94
95 static const struct super_operations devpts_sops = {
96         .statfs         = simple_statfs,
97         .remount_fs     = devpts_remount,
98 };
99
100 static int
101 devpts_fill_super(struct super_block *s, void *data, int silent)
102 {
103         struct inode * inode;
104
105         s->s_blocksize = 1024;
106         s->s_blocksize_bits = 10;
107         s->s_magic = DEVPTS_SUPER_MAGIC;
108         s->s_op = &devpts_sops;
109         s->s_time_gran = 1;
110
111         inode = new_inode(s);
112         if (!inode)
113                 goto fail;
114         inode->i_ino = 1;
115         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
116         inode->i_blocks = 0;
117         inode->i_uid = inode->i_gid = 0;
118         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
119         inode->i_op = &simple_dir_inode_operations;
120         inode->i_fop = &simple_dir_operations;
121         inode->i_nlink = 2;
122
123         devpts_root = s->s_root = d_alloc_root(inode);
124         if (s->s_root)
125                 return 0;
126         
127         printk("devpts: get root dentry failed\n");
128         iput(inode);
129 fail:
130         return -ENOMEM;
131 }
132
133 static int devpts_get_sb(struct file_system_type *fs_type,
134         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
135 {
136         return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
137 }
138
139 static struct file_system_type devpts_fs_type = {
140         .owner          = THIS_MODULE,
141         .name           = "devpts",
142         .get_sb         = devpts_get_sb,
143         .kill_sb        = kill_anon_super,
144 };
145
146 /*
147  * The normal naming convention is simply /dev/pts/<number>; this conforms
148  * to the System V naming convention
149  */
150
151 static struct dentry *get_node(int num)
152 {
153         char s[12];
154         struct dentry *root = devpts_root;
155         mutex_lock(&root->d_inode->i_mutex);
156         return lookup_one_len(s, root, sprintf(s, "%d", num));
157 }
158
159 int devpts_pty_new(struct tty_struct *tty)
160 {
161         int number = tty->index;
162         struct tty_driver *driver = tty->driver;
163         dev_t device = MKDEV(driver->major, driver->minor_start+number);
164         struct dentry *dentry;
165         struct inode *inode = new_inode(devpts_mnt->mnt_sb);
166
167         /* We're supposed to be given the slave end of a pty */
168         BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
169         BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
170
171         if (!inode)
172                 return -ENOMEM;
173
174         inode->i_ino = number+2;
175         inode->i_uid = config.setuid ? config.uid : current->fsuid;
176         inode->i_gid = config.setgid ? config.gid : current->fsgid;
177         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
178         init_special_inode(inode, S_IFCHR|config.mode, device);
179         inode->i_private = tty;
180
181         dentry = get_node(number);
182         if (!IS_ERR(dentry) && !dentry->d_inode) {
183                 d_instantiate(dentry, inode);
184                 fsnotify_create(devpts_root->d_inode, dentry);
185         }
186
187         mutex_unlock(&devpts_root->d_inode->i_mutex);
188
189         return 0;
190 }
191
192 struct tty_struct *devpts_get_tty(int number)
193 {
194         struct dentry *dentry = get_node(number);
195         struct tty_struct *tty;
196
197         tty = NULL;
198         if (!IS_ERR(dentry)) {
199                 if (dentry->d_inode)
200                         tty = dentry->d_inode->i_private;
201                 dput(dentry);
202         }
203
204         mutex_unlock(&devpts_root->d_inode->i_mutex);
205
206         return tty;
207 }
208
209 void devpts_pty_kill(int number)
210 {
211         struct dentry *dentry = get_node(number);
212
213         if (!IS_ERR(dentry)) {
214                 struct inode *inode = dentry->d_inode;
215                 if (inode) {
216                         inode->i_nlink--;
217                         d_delete(dentry);
218                         dput(dentry);
219                 }
220                 dput(dentry);
221         }
222         mutex_unlock(&devpts_root->d_inode->i_mutex);
223 }
224
225 static int __init init_devpts_fs(void)
226 {
227         int err = register_filesystem(&devpts_fs_type);
228         if (!err) {
229                 devpts_mnt = kern_mount(&devpts_fs_type);
230                 if (IS_ERR(devpts_mnt))
231                         err = PTR_ERR(devpts_mnt);
232         }
233         return err;
234 }
235
236 static void __exit exit_devpts_fs(void)
237 {
238         unregister_filesystem(&devpts_fs_type);
239         mntput(devpts_mnt);
240 }
241
242 module_init(init_devpts_fs)
243 module_exit(exit_devpts_fs)
244 MODULE_LICENSE("GPL");