2 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Added support for a Unix98-style ptmx device.
5 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
7 * When reading this code see also fs/devpts. In particular note that the
8 * driver_data field is used by the devpts side as a binding to the devpts
12 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/interrupt.h>
16 #include <linux/tty.h>
17 #include <linux/tty_flip.h>
18 #include <linux/fcntl.h>
19 #include <linux/sched.h>
20 #include <linux/string.h>
21 #include <linux/major.h>
23 #include <linux/init.h>
24 #include <linux/device.h>
25 #include <linux/uaccess.h>
26 #include <linux/bitops.h>
27 #include <linux/devpts_fs.h>
28 #include <linux/slab.h>
29 #include <linux/mutex.h>
32 #ifdef CONFIG_UNIX98_PTYS
33 static struct tty_driver *ptm_driver;
34 static struct tty_driver *pts_driver;
35 static DEFINE_MUTEX(devpts_mutex);
38 static void pty_close(struct tty_struct *tty, struct file *filp)
41 if (tty->driver->subtype == PTY_TYPE_MASTER)
42 WARN_ON(tty->count > 1);
47 wake_up_interruptible(&tty->read_wait);
48 wake_up_interruptible(&tty->write_wait);
52 tty->link->packet = 0;
53 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
54 wake_up_interruptible(&tty->link->read_wait);
55 wake_up_interruptible(&tty->link->write_wait);
56 if (tty->driver->subtype == PTY_TYPE_MASTER) {
57 set_bit(TTY_OTHER_CLOSED, &tty->flags);
58 #ifdef CONFIG_UNIX98_PTYS
59 if (tty->driver == ptm_driver) {
60 mutex_lock(&devpts_mutex);
61 devpts_pty_kill(tty->link);
62 mutex_unlock(&devpts_mutex);
66 tty_vhangup(tty->link);
72 * The unthrottle routine is called by the line discipline to signal
73 * that it can receive more characters. For PTY's, the TTY_THROTTLED
74 * flag is always set, to force the line discipline to always call the
75 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
76 * characters in the queue. This is necessary since each time this
77 * happens, we need to wake up any sleeping processes that could be
78 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
79 * for the pty buffer to be drained.
81 static void pty_unthrottle(struct tty_struct *tty)
83 tty_wakeup(tty->link);
84 set_bit(TTY_THROTTLED, &tty->flags);
88 * pty_space - report space left for writing
89 * @to: tty we are writing into
91 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
92 * allows a lot of overspill room for echo and other fun messes to
96 static int pty_space(struct tty_struct *to)
98 int n = 8192 - to->buf.memory_used;
105 * pty_write - write to a pty
106 * @tty: the tty we write from
107 * @buf: kernel buffer of data
108 * @count: bytes to write
110 * Our "hardware" write method. Data is coming from the ldisc which
111 * may be in a non sleeping state. We simply throw this at the other
112 * end of the link as if we were an IRQ handler receiving stuff for
113 * the other side of the pty/tty pair.
116 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
118 struct tty_struct *to = tty->link;
124 /* Stuff the data into the input queue of the other end */
125 c = tty_insert_flip_string(to, buf, c);
128 tty_flip_buffer_push(to);
136 * pty_write_room - write space
137 * @tty: tty we are writing from
139 * Report how many bytes the ldisc can send into the queue for
143 static int pty_write_room(struct tty_struct *tty)
147 return pty_space(tty->link);
151 * pty_chars_in_buffer - characters currently in our tx queue
154 * Report how much we have in the transmit queue. As everything is
155 * instantly at the other end this is easy to implement.
158 static int pty_chars_in_buffer(struct tty_struct *tty)
163 /* Set the lock flag on a pty */
164 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
167 if (get_user(val, arg))
170 set_bit(TTY_PTY_LOCK, &tty->flags);
172 clear_bit(TTY_PTY_LOCK, &tty->flags);
176 /* Send a signal to the slave */
177 static int pty_signal(struct tty_struct *tty, int sig)
183 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
184 pgrp = get_pid(tty->link->pgrp);
185 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
187 kill_pgrp(pgrp, sig, 1);
193 static void pty_flush_buffer(struct tty_struct *tty)
195 struct tty_struct *to = tty->link;
200 /* tty_buffer_flush(to); FIXME */
202 spin_lock_irqsave(&tty->ctrl_lock, flags);
203 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
204 wake_up_interruptible(&to->read_wait);
205 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
209 static int pty_open(struct tty_struct *tty, struct file *filp)
211 int retval = -ENODEV;
213 if (!tty || !tty->link)
217 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
219 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
221 if (tty->link->count != 1)
224 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
225 set_bit(TTY_THROTTLED, &tty->flags);
231 static void pty_set_termios(struct tty_struct *tty,
232 struct ktermios *old_termios)
234 tty->termios->c_cflag &= ~(CSIZE | PARENB);
235 tty->termios->c_cflag |= (CS8 | CREAD);
239 * pty_do_resize - resize event
240 * @tty: tty being resized
241 * @ws: window size being set.
243 * Update the termios variables and send the necessary signals to
244 * peform a terminal resize correctly
247 int pty_resize(struct tty_struct *tty, struct winsize *ws)
249 struct pid *pgrp, *rpgrp;
251 struct tty_struct *pty = tty->link;
253 /* For a PTY we need to lock the tty side */
254 mutex_lock(&tty->termios_mutex);
255 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
258 /* Get the PID values and reference them so we can
259 avoid holding the tty ctrl lock while sending signals.
260 We need to lock these individually however. */
262 spin_lock_irqsave(&tty->ctrl_lock, flags);
263 pgrp = get_pid(tty->pgrp);
264 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
266 spin_lock_irqsave(&pty->ctrl_lock, flags);
267 rpgrp = get_pid(pty->pgrp);
268 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
271 kill_pgrp(pgrp, SIGWINCH, 1);
272 if (rpgrp != pgrp && rpgrp)
273 kill_pgrp(rpgrp, SIGWINCH, 1);
279 pty->winsize = *ws; /* Never used so will go away soon */
281 mutex_unlock(&tty->termios_mutex);
285 /* Traditional BSD devices */
286 #ifdef CONFIG_LEGACY_PTYS
288 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
290 struct tty_struct *o_tty;
291 int idx = tty->index;
294 o_tty = alloc_tty_struct();
297 if (!try_module_get(driver->other->owner)) {
298 /* This cannot in fact currently happen */
302 initialize_tty_struct(o_tty, driver->other, idx);
304 /* We always use new tty termios data so we can do this
306 retval = tty_init_termios(tty);
310 retval = tty_init_termios(o_tty);
312 goto err_free_termios;
315 * Everything allocated ... set up the o_tty structure.
317 driver->other->ttys[idx] = o_tty;
318 tty_driver_kref_get(driver->other);
319 if (driver->subtype == PTY_TYPE_MASTER)
321 /* Establish the links in both directions */
325 tty_driver_kref_get(driver);
327 driver->ttys[idx] = tty;
330 tty_free_termios(tty);
332 deinitialize_tty_struct(o_tty);
333 module_put(o_tty->driver->owner);
335 free_tty_struct(o_tty);
339 static int pty_bsd_ioctl(struct tty_struct *tty,
340 unsigned int cmd, unsigned long arg)
343 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
344 return pty_set_lock(tty, (int __user *) arg);
345 case TIOCSIG: /* Send signal to other side of pty */
346 return pty_signal(tty, (int) arg);
351 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
352 module_param(legacy_count, int, 0);
355 * The master side of a pty can do TIOCSPTLCK and thus
358 static const struct tty_operations master_pty_ops_bsd = {
359 .install = pty_install,
363 .write_room = pty_write_room,
364 .flush_buffer = pty_flush_buffer,
365 .chars_in_buffer = pty_chars_in_buffer,
366 .unthrottle = pty_unthrottle,
367 .set_termios = pty_set_termios,
368 .ioctl = pty_bsd_ioctl,
372 static const struct tty_operations slave_pty_ops_bsd = {
373 .install = pty_install,
377 .write_room = pty_write_room,
378 .flush_buffer = pty_flush_buffer,
379 .chars_in_buffer = pty_chars_in_buffer,
380 .unthrottle = pty_unthrottle,
381 .set_termios = pty_set_termios,
385 static void __init legacy_pty_init(void)
387 struct tty_driver *pty_driver, *pty_slave_driver;
389 if (legacy_count <= 0)
392 pty_driver = alloc_tty_driver(legacy_count);
394 panic("Couldn't allocate pty driver");
396 pty_slave_driver = alloc_tty_driver(legacy_count);
397 if (!pty_slave_driver)
398 panic("Couldn't allocate pty slave driver");
400 pty_driver->driver_name = "pty_master";
401 pty_driver->name = "pty";
402 pty_driver->major = PTY_MASTER_MAJOR;
403 pty_driver->minor_start = 0;
404 pty_driver->type = TTY_DRIVER_TYPE_PTY;
405 pty_driver->subtype = PTY_TYPE_MASTER;
406 pty_driver->init_termios = tty_std_termios;
407 pty_driver->init_termios.c_iflag = 0;
408 pty_driver->init_termios.c_oflag = 0;
409 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
410 pty_driver->init_termios.c_lflag = 0;
411 pty_driver->init_termios.c_ispeed = 38400;
412 pty_driver->init_termios.c_ospeed = 38400;
413 pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
414 pty_driver->other = pty_slave_driver;
415 tty_set_operations(pty_driver, &master_pty_ops_bsd);
417 pty_slave_driver->driver_name = "pty_slave";
418 pty_slave_driver->name = "ttyp";
419 pty_slave_driver->major = PTY_SLAVE_MAJOR;
420 pty_slave_driver->minor_start = 0;
421 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
422 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
423 pty_slave_driver->init_termios = tty_std_termios;
424 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
425 pty_slave_driver->init_termios.c_ispeed = 38400;
426 pty_slave_driver->init_termios.c_ospeed = 38400;
427 pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
429 pty_slave_driver->other = pty_driver;
430 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
432 if (tty_register_driver(pty_driver))
433 panic("Couldn't register pty driver");
434 if (tty_register_driver(pty_slave_driver))
435 panic("Couldn't register pty slave driver");
438 static inline void legacy_pty_init(void) { }
442 #ifdef CONFIG_UNIX98_PTYS
444 static struct cdev ptmx_cdev;
446 static int pty_unix98_ioctl(struct tty_struct *tty,
447 unsigned int cmd, unsigned long arg)
450 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
451 return pty_set_lock(tty, (int __user *)arg);
452 case TIOCGPTN: /* Get PT Number */
453 return put_user(tty->index, (unsigned int __user *)arg);
454 case TIOCSIG: /* Send signal to other side of pty */
455 return pty_signal(tty, (int) arg);
462 * ptm_unix98_lookup - find a pty master
463 * @driver: ptm driver
466 * Look up a pty master device. Called under the tty_mutex for now.
467 * This provides our locking.
470 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
471 struct inode *ptm_inode, int idx)
473 /* Master must be open via /dev/ptmx */
474 return ERR_PTR(-EIO);
478 * pts_unix98_lookup - find a pty slave
479 * @driver: pts driver
482 * Look up a pty master device. Called under the tty_mutex for now.
483 * This provides our locking for the tty pointer.
486 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
487 struct inode *pts_inode, int idx)
489 struct tty_struct *tty;
491 mutex_lock(&devpts_mutex);
492 tty = devpts_get_tty(pts_inode, idx);
493 mutex_unlock(&devpts_mutex);
494 /* Master must be open before slave */
496 return ERR_PTR(-EIO);
500 static void pty_unix98_shutdown(struct tty_struct *tty)
502 tty_driver_remove_tty(tty->driver, tty);
503 /* We have our own method as we don't use the tty index */
507 /* We have no need to install and remove our tty objects as devpts does all
510 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
512 struct tty_struct *o_tty;
513 int idx = tty->index;
515 o_tty = alloc_tty_struct();
518 if (!try_module_get(driver->other->owner)) {
519 /* This cannot in fact currently happen */
522 initialize_tty_struct(o_tty, driver->other, idx);
524 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
525 if (tty->termios == NULL)
527 *tty->termios = driver->init_termios;
528 tty->termios_locked = tty->termios + 1;
530 o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
531 if (o_tty->termios == NULL)
533 *o_tty->termios = driver->other->init_termios;
534 o_tty->termios_locked = o_tty->termios + 1;
536 tty_driver_kref_get(driver->other);
537 if (driver->subtype == PTY_TYPE_MASTER)
539 /* Establish the links in both directions */
543 * All structures have been allocated, so now we install them.
544 * Failures after this point use release_tty to clean up, so
545 * there's no need to null out the local pointers.
547 tty_driver_kref_get(driver);
551 deinitialize_tty_struct(o_tty);
552 kfree(o_tty->termios);
554 module_put(o_tty->driver->owner);
556 free_tty_struct(o_tty);
560 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
564 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
568 static const struct tty_operations ptm_unix98_ops = {
569 .lookup = ptm_unix98_lookup,
570 .install = pty_unix98_install,
571 .remove = ptm_unix98_remove,
575 .write_room = pty_write_room,
576 .flush_buffer = pty_flush_buffer,
577 .chars_in_buffer = pty_chars_in_buffer,
578 .unthrottle = pty_unthrottle,
579 .set_termios = pty_set_termios,
580 .ioctl = pty_unix98_ioctl,
581 .shutdown = pty_unix98_shutdown,
585 static const struct tty_operations pty_unix98_ops = {
586 .lookup = pts_unix98_lookup,
587 .install = pty_unix98_install,
588 .remove = pts_unix98_remove,
592 .write_room = pty_write_room,
593 .flush_buffer = pty_flush_buffer,
594 .chars_in_buffer = pty_chars_in_buffer,
595 .unthrottle = pty_unthrottle,
596 .set_termios = pty_set_termios,
597 .shutdown = pty_unix98_shutdown
601 * ptmx_open - open a unix 98 pty master
602 * @inode: inode of device file
603 * @filp: file pointer to tty
605 * Allocate a unix98 pty master device from the ptmx driver.
607 * Locking: tty_mutex protects the init_dev work. tty->count should
609 * allocated_ptys_lock handles the list of free pty numbers
612 static int ptmx_open(struct inode *inode, struct file *filp)
614 struct tty_struct *tty;
618 nonseekable_open(inode, filp);
620 retval = tty_alloc_file(filp);
624 /* find a device that is not in use. */
626 index = devpts_new_index(inode);
633 mutex_lock(&tty_mutex);
634 mutex_lock(&devpts_mutex);
635 tty = tty_init_dev(ptm_driver, index);
636 mutex_unlock(&devpts_mutex);
638 mutex_unlock(&tty_mutex);
641 retval = PTR_ERR(tty);
645 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
647 tty_add_file(tty, filp);
649 retval = devpts_pty_new(inode, tty->link);
653 retval = ptm_driver->ops->open(tty, filp);
661 tty_release(inode, filp);
664 devpts_kill_index(inode, index);
671 static struct file_operations ptmx_fops;
673 static void __init unix98_pty_init(void)
675 ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
677 panic("Couldn't allocate Unix98 ptm driver");
678 pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
680 panic("Couldn't allocate Unix98 pts driver");
682 ptm_driver->driver_name = "pty_master";
683 ptm_driver->name = "ptm";
684 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
685 ptm_driver->minor_start = 0;
686 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
687 ptm_driver->subtype = PTY_TYPE_MASTER;
688 ptm_driver->init_termios = tty_std_termios;
689 ptm_driver->init_termios.c_iflag = 0;
690 ptm_driver->init_termios.c_oflag = 0;
691 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
692 ptm_driver->init_termios.c_lflag = 0;
693 ptm_driver->init_termios.c_ispeed = 38400;
694 ptm_driver->init_termios.c_ospeed = 38400;
695 ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
696 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
697 ptm_driver->other = pts_driver;
698 tty_set_operations(ptm_driver, &ptm_unix98_ops);
700 pts_driver->driver_name = "pty_slave";
701 pts_driver->name = "pts";
702 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
703 pts_driver->minor_start = 0;
704 pts_driver->type = TTY_DRIVER_TYPE_PTY;
705 pts_driver->subtype = PTY_TYPE_SLAVE;
706 pts_driver->init_termios = tty_std_termios;
707 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
708 pts_driver->init_termios.c_ispeed = 38400;
709 pts_driver->init_termios.c_ospeed = 38400;
710 pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
711 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
712 pts_driver->other = ptm_driver;
713 tty_set_operations(pts_driver, &pty_unix98_ops);
715 if (tty_register_driver(ptm_driver))
716 panic("Couldn't register Unix98 ptm driver");
717 if (tty_register_driver(pts_driver))
718 panic("Couldn't register Unix98 pts driver");
720 /* Now create the /dev/ptmx special device */
721 tty_default_fops(&ptmx_fops);
722 ptmx_fops.open = ptmx_open;
724 cdev_init(&ptmx_cdev, &ptmx_fops);
725 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
726 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
727 panic("Couldn't register /dev/ptmx driver\n");
728 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
732 static inline void unix98_pty_init(void) { }
735 static int __init pty_init(void)
741 module_init(pty_init);