blob: 76b27932d229df31d3ff24f7d09e83afecdb278a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/drivers/char/pty.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * Added support for a Unix98-style ptmx device.
7 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
8 * Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
9 * waiting writers -- Sapan Bhatia <sapan@corewars.org>
10 *
11 *
12 */
13
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/module.h> /* For EXPORT_SYMBOL */
15
16#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/interrupt.h>
18#include <linux/tty.h>
19#include <linux/tty_flip.h>
20#include <linux/fcntl.h>
21#include <linux/string.h>
22#include <linux/major.h>
23#include <linux/mm.h>
24#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/sysctl.h>
26
27#include <asm/uaccess.h>
28#include <asm/system.h>
29#include <linux/bitops.h>
30#include <linux/devpts_fs.h>
31
32/* These are global because they are accessed in tty_io.c */
33#ifdef CONFIG_UNIX98_PTYS
34struct tty_driver *ptm_driver;
35static struct tty_driver *pts_driver;
36#endif
37
38static void pty_close(struct tty_struct * tty, struct file * filp)
39{
40 if (!tty)
41 return;
42 if (tty->driver->subtype == PTY_TYPE_MASTER) {
43 if (tty->count > 1)
44 printk("master pty_close: count = %d!!\n", tty->count);
45 } else {
46 if (tty->count > 2)
47 return;
48 }
49 wake_up_interruptible(&tty->read_wait);
50 wake_up_interruptible(&tty->write_wait);
51 tty->packet = 0;
52 if (!tty->link)
53 return;
54 tty->link->packet = 0;
55 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
56 wake_up_interruptible(&tty->link->read_wait);
57 wake_up_interruptible(&tty->link->write_wait);
58 if (tty->driver->subtype == PTY_TYPE_MASTER) {
59 set_bit(TTY_OTHER_CLOSED, &tty->flags);
60#ifdef CONFIG_UNIX98_PTYS
61 if (tty->driver == ptm_driver)
62 devpts_pty_kill(tty->index);
63#endif
64 tty_vhangup(tty->link);
65 }
66}
67
68/*
69 * The unthrottle routine is called by the line discipline to signal
70 * that it can receive more characters. For PTY's, the TTY_THROTTLED
71 * flag is always set, to force the line discipline to always call the
72 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
73 * characters in the queue. This is necessary since each time this
74 * happens, we need to wake up any sleeping processes that could be
75 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
76 * for the pty buffer to be drained.
77 */
78static void pty_unthrottle(struct tty_struct * tty)
79{
80 struct tty_struct *o_tty = tty->link;
81
82 if (!o_tty)
83 return;
84
85 tty_wakeup(o_tty);
86 set_bit(TTY_THROTTLED, &tty->flags);
87}
88
89/*
90 * WSH 05/24/97: modified to
91 * (1) use space in tty->flip instead of a shared temp buffer
92 * The flip buffers aren't being used for a pty, so there's lots
93 * of space available. The buffer is protected by a per-pty
94 * semaphore that should almost never come under contention.
95 * (2) avoid redundant copying for cases where count >> receive_room
96 * N.B. Calls from user space may now return an error code instead of
97 * a count.
98 *
99 * FIXME: Our pty_write method is called with our ldisc lock held but
100 * not our partners. We can't just take the other one blindly without
Paul Fulghum817d6d32006-06-28 04:26:47 -0700101 * risking deadlocks.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 */
103static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
104{
105 struct tty_struct *to = tty->link;
106 int c;
107
108 if (!to || tty->stopped)
109 return 0;
110
Alan Cox33f0f882006-01-09 20:54:13 -0800111 c = to->receive_room;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 if (c > count)
113 c = count;
Alan Coxa352def2008-07-16 21:53:12 +0100114 to->ldisc.ops->receive_buf(to, buf, NULL, c);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116 return c;
117}
118
119static int pty_write_room(struct tty_struct *tty)
120{
121 struct tty_struct *to = tty->link;
122
123 if (!to || tty->stopped)
124 return 0;
125
Alan Cox33f0f882006-01-09 20:54:13 -0800126 return to->receive_room;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
128
129/*
130 * WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
131 * The chars_in_buffer() value is used by the ldisc select() function
132 * to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
133 * The pty driver chars_in_buffer() Master/Slave must behave differently:
134 *
135 * The Master side needs to allow typed-ahead commands to accumulate
136 * while being canonicalized, so we report "our buffer" as empty until
137 * some threshold is reached, and then report the count. (Any count >
138 * WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
139 * the count returned must be 0 if no canonical data is available to be
140 * read. (The N_TTY ldisc.chars_in_buffer now knows this.)
141 *
142 * The Slave side passes all characters in raw mode to the Master side's
143 * buffer where they can be read immediately, so in this case we can
144 * return the true count in the buffer.
145 */
146static int pty_chars_in_buffer(struct tty_struct *tty)
147{
148 struct tty_struct *to = tty->link;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 int count;
150
151 /* We should get the line discipline lock for "tty->link" */
Alan Coxa352def2008-07-16 21:53:12 +0100152 if (!to || !to->ldisc.ops->chars_in_buffer)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 return 0;
154
155 /* The ldisc must report 0 if no characters available to be read */
Alan Coxa352def2008-07-16 21:53:12 +0100156 count = to->ldisc.ops->chars_in_buffer(to);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158 if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
159
160 /* Master side driver ... if the other side's read buffer is less than
161 * half full, return 0 to allow writers to proceed; otherwise return
162 * the count. This leaves a comfortable margin to avoid overflow,
163 * and still allows half a buffer's worth of typed-ahead commands.
164 */
165 return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
166}
167
168/* Set the lock flag on a pty */
169static int pty_set_lock(struct tty_struct *tty, int __user * arg)
170{
171 int val;
172 if (get_user(val,arg))
173 return -EFAULT;
174 if (val)
175 set_bit(TTY_PTY_LOCK, &tty->flags);
176 else
177 clear_bit(TTY_PTY_LOCK, &tty->flags);
178 return 0;
179}
180
181static void pty_flush_buffer(struct tty_struct *tty)
182{
183 struct tty_struct *to = tty->link;
Alan Cox04f378b2008-04-30 00:53:29 -0700184 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
186 if (!to)
187 return;
188
Alan Coxa352def2008-07-16 21:53:12 +0100189 if (to->ldisc.ops->flush_buffer)
190 to->ldisc.ops->flush_buffer(to);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
192 if (to->packet) {
Alan Cox04f378b2008-04-30 00:53:29 -0700193 spin_lock_irqsave(&tty->ctrl_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
195 wake_up_interruptible(&to->read_wait);
Alan Cox04f378b2008-04-30 00:53:29 -0700196 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 }
198}
199
200static int pty_open(struct tty_struct *tty, struct file * filp)
201{
202 int retval = -ENODEV;
203
204 if (!tty || !tty->link)
205 goto out;
206
207 retval = -EIO;
208 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
209 goto out;
210 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
211 goto out;
212 if (tty->link->count != 1)
213 goto out;
214
215 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
216 set_bit(TTY_THROTTLED, &tty->flags);
217 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
218 retval = 0;
219out:
220 return retval;
221}
222
Alan Cox606d0992006-12-08 02:38:45 -0800223static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 tty->termios->c_cflag &= ~(CSIZE | PARENB);
226 tty->termios->c_cflag |= (CS8 | CREAD);
227}
228
Jeff Dikeb68e31d2006-10-02 02:17:18 -0700229static const struct tty_operations pty_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 .open = pty_open,
231 .close = pty_close,
232 .write = pty_write,
233 .write_room = pty_write_room,
234 .flush_buffer = pty_flush_buffer,
235 .chars_in_buffer = pty_chars_in_buffer,
236 .unthrottle = pty_unthrottle,
237 .set_termios = pty_set_termios,
238};
239
240/* Traditional BSD devices */
241#ifdef CONFIG_LEGACY_PTYS
242static struct tty_driver *pty_driver, *pty_slave_driver;
243
244static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
245 unsigned int cmd, unsigned long arg)
246{
247 switch (cmd) {
248 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
249 return pty_set_lock(tty, (int __user *) arg);
250 }
251 return -ENOIOCTLCMD;
252}
253
Kay Sieversdc8c8582007-08-15 12:25:38 +0200254static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
255module_param(legacy_count, int, 0);
256
Alan Cox3e8e88c2008-04-30 00:54:10 -0700257static const struct tty_operations pty_ops_bsd = {
258 .open = pty_open,
259 .close = pty_close,
260 .write = pty_write,
261 .write_room = pty_write_room,
262 .flush_buffer = pty_flush_buffer,
263 .chars_in_buffer = pty_chars_in_buffer,
264 .unthrottle = pty_unthrottle,
265 .set_termios = pty_set_termios,
266 .ioctl = pty_bsd_ioctl,
267};
268
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269static void __init legacy_pty_init(void)
270{
Kay Sieversdc8c8582007-08-15 12:25:38 +0200271 if (legacy_count <= 0)
272 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Kay Sieversdc8c8582007-08-15 12:25:38 +0200274 pty_driver = alloc_tty_driver(legacy_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 if (!pty_driver)
276 panic("Couldn't allocate pty driver");
277
Kay Sieversdc8c8582007-08-15 12:25:38 +0200278 pty_slave_driver = alloc_tty_driver(legacy_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 if (!pty_slave_driver)
280 panic("Couldn't allocate pty slave driver");
281
282 pty_driver->owner = THIS_MODULE;
283 pty_driver->driver_name = "pty_master";
284 pty_driver->name = "pty";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 pty_driver->major = PTY_MASTER_MAJOR;
286 pty_driver->minor_start = 0;
287 pty_driver->type = TTY_DRIVER_TYPE_PTY;
288 pty_driver->subtype = PTY_TYPE_MASTER;
289 pty_driver->init_termios = tty_std_termios;
290 pty_driver->init_termios.c_iflag = 0;
291 pty_driver->init_termios.c_oflag = 0;
292 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
293 pty_driver->init_termios.c_lflag = 0;
Alan Cox606d0992006-12-08 02:38:45 -0800294 pty_driver->init_termios.c_ispeed = 38400;
295 pty_driver->init_termios.c_ospeed = 38400;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
297 pty_driver->other = pty_slave_driver;
298 tty_set_operations(pty_driver, &pty_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
300 pty_slave_driver->owner = THIS_MODULE;
301 pty_slave_driver->driver_name = "pty_slave";
302 pty_slave_driver->name = "ttyp";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 pty_slave_driver->major = PTY_SLAVE_MAJOR;
304 pty_slave_driver->minor_start = 0;
305 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
306 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
307 pty_slave_driver->init_termios = tty_std_termios;
308 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
Alan Cox606d0992006-12-08 02:38:45 -0800309 pty_slave_driver->init_termios.c_ispeed = 38400;
310 pty_slave_driver->init_termios.c_ospeed = 38400;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
312 TTY_DRIVER_REAL_RAW;
313 pty_slave_driver->other = pty_driver;
314 tty_set_operations(pty_slave_driver, &pty_ops);
315
316 if (tty_register_driver(pty_driver))
317 panic("Couldn't register pty driver");
318 if (tty_register_driver(pty_slave_driver))
319 panic("Couldn't register pty slave driver");
320}
321#else
322static inline void legacy_pty_init(void) { }
323#endif
324
325/* Unix98 devices */
326#ifdef CONFIG_UNIX98_PTYS
327/*
328 * sysctl support for setting limits on the number of Unix98 ptys allocated.
329 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
330 */
331int pty_limit = NR_UNIX98_PTY_DEFAULT;
332static int pty_limit_min = 0;
333static int pty_limit_max = NR_UNIX98_PTY_MAX;
334
Eric W. Biederman35834ca2007-10-18 03:05:31 -0700335static struct ctl_table pty_table[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 {
337 .ctl_name = PTY_MAX,
338 .procname = "max",
339 .maxlen = sizeof(int),
340 .mode = 0644,
341 .data = &pty_limit,
342 .proc_handler = &proc_dointvec_minmax,
343 .strategy = &sysctl_intvec,
344 .extra1 = &pty_limit_min,
345 .extra2 = &pty_limit_max,
346 }, {
347 .ctl_name = PTY_NR,
348 .procname = "nr",
349 .maxlen = sizeof(int),
350 .mode = 0444,
351 .proc_handler = &proc_dointvec,
352 }, {
353 .ctl_name = 0
354 }
355};
356
Eric W. Biederman35834ca2007-10-18 03:05:31 -0700357static struct ctl_table pty_kern_table[] = {
358 {
359 .ctl_name = KERN_PTY,
360 .procname = "pty",
361 .mode = 0555,
362 .child = pty_table,
363 },
364 {}
365};
366
367static struct ctl_table pty_root_table[] = {
368 {
369 .ctl_name = CTL_KERN,
370 .procname = "kernel",
371 .mode = 0555,
372 .child = pty_kern_table,
373 },
374 {}
375};
376
377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
379 unsigned int cmd, unsigned long arg)
380{
381 switch (cmd) {
382 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
383 return pty_set_lock(tty, (int __user *)arg);
384 case TIOCGPTN: /* Get PT Number */
385 return put_user(tty->index, (unsigned int __user *)arg);
386 }
387
388 return -ENOIOCTLCMD;
389}
390
Alan Cox3e8e88c2008-04-30 00:54:10 -0700391static const struct tty_operations pty_unix98_ops = {
392 .open = pty_open,
393 .close = pty_close,
394 .write = pty_write,
395 .write_room = pty_write_room,
396 .flush_buffer = pty_flush_buffer,
397 .chars_in_buffer = pty_chars_in_buffer,
398 .unthrottle = pty_unthrottle,
399 .set_termios = pty_set_termios,
400 .ioctl = pty_unix98_ioctl
401};
402
403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404static void __init unix98_pty_init(void)
405{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
407 if (!ptm_driver)
408 panic("Couldn't allocate Unix98 ptm driver");
409 pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
410 if (!pts_driver)
411 panic("Couldn't allocate Unix98 pts driver");
412
413 ptm_driver->owner = THIS_MODULE;
414 ptm_driver->driver_name = "pty_master";
415 ptm_driver->name = "ptm";
416 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
417 ptm_driver->minor_start = 0;
418 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
419 ptm_driver->subtype = PTY_TYPE_MASTER;
420 ptm_driver->init_termios = tty_std_termios;
421 ptm_driver->init_termios.c_iflag = 0;
422 ptm_driver->init_termios.c_oflag = 0;
423 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
424 ptm_driver->init_termios.c_lflag = 0;
Alan Cox606d0992006-12-08 02:38:45 -0800425 ptm_driver->init_termios.c_ispeed = 38400;
426 ptm_driver->init_termios.c_ospeed = 38400;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
Greg Kroah-Hartman331b8312005-06-20 21:15:16 -0700428 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 ptm_driver->other = pts_driver;
Alan Cox3e8e88c2008-04-30 00:54:10 -0700430 tty_set_operations(ptm_driver, &pty_unix98_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
432 pts_driver->owner = THIS_MODULE;
433 pts_driver->driver_name = "pty_slave";
434 pts_driver->name = "pts";
435 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
436 pts_driver->minor_start = 0;
437 pts_driver->type = TTY_DRIVER_TYPE_PTY;
438 pts_driver->subtype = PTY_TYPE_SLAVE;
439 pts_driver->init_termios = tty_std_termios;
440 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
Alan Cox606d0992006-12-08 02:38:45 -0800441 pts_driver->init_termios.c_ispeed = 38400;
442 pts_driver->init_termios.c_ospeed = 38400;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
Greg Kroah-Hartman331b8312005-06-20 21:15:16 -0700444 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 pts_driver->other = ptm_driver;
446 tty_set_operations(pts_driver, &pty_ops);
447
448 if (tty_register_driver(ptm_driver))
449 panic("Couldn't register Unix98 ptm driver");
450 if (tty_register_driver(pts_driver))
451 panic("Couldn't register Unix98 pts driver");
452
453 pty_table[1].data = &ptm_driver->refcount;
Eric W. Biederman35834ca2007-10-18 03:05:31 -0700454 register_sysctl_table(pty_root_table);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455}
456#else
457static inline void unix98_pty_init(void) { }
458#endif
459
460static int __init pty_init(void)
461{
462 legacy_pty_init();
463 unix98_pty_init();
464 return 0;
465}
466module_init(pty_init);