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
9 #include <linux/module.h>
11 #include <linux/errno.h>
12 #include <linux/interrupt.h>
13 #include <linux/tty.h>
14 #include <linux/tty_flip.h>
15 #include <linux/fcntl.h>
16 #include <linux/sched.h>
17 #include <linux/string.h>
18 #include <linux/major.h>
20 #include <linux/init.h>
21 #include <linux/device.h>
22 #include <linux/uaccess.h>
23 #include <linux/bitops.h>
24 #include <linux/devpts_fs.h>
25 #include <linux/slab.h>
26 #include <linux/mutex.h>
27 #include <linux/poll.h>
30 #ifdef CONFIG_UNIX98_PTYS
31 static struct tty_driver *ptm_driver;
32 static struct tty_driver *pts_driver;
33 static DEFINE_MUTEX(devpts_mutex);
36 static void pty_close(struct tty_struct *tty, struct file *filp)
39 if (tty->driver->subtype == PTY_TYPE_MASTER)
40 WARN_ON(tty->count > 1);
42 if (test_bit(TTY_IO_ERROR, &tty->flags))
47 set_bit(TTY_IO_ERROR, &tty->flags);
48 wake_up_interruptible(&tty->read_wait);
49 wake_up_interruptible(&tty->write_wait);
51 /* Review - krefs on tty_link ?? */
54 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
55 wake_up_interruptible(&tty->link->read_wait);
56 wake_up_interruptible(&tty->link->write_wait);
57 if (tty->driver->subtype == PTY_TYPE_MASTER) {
58 set_bit(TTY_OTHER_CLOSED, &tty->flags);
59 #ifdef CONFIG_UNIX98_PTYS
60 if (tty->driver == ptm_driver) {
61 mutex_lock(&devpts_mutex);
62 if (tty->link->driver_data)
63 devpts_pty_kill(tty->link->driver_data);
64 mutex_unlock(&devpts_mutex);
68 tty_vhangup(tty->link);
74 * The unthrottle routine is called by the line discipline to signal
75 * that it can receive more characters. For PTY's, the TTY_THROTTLED
76 * flag is always set, to force the line discipline to always call the
77 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
78 * characters in the queue. This is necessary since each time this
79 * happens, we need to wake up any sleeping processes that could be
80 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
81 * for the pty buffer to be drained.
83 static void pty_unthrottle(struct tty_struct *tty)
85 tty_wakeup(tty->link);
86 set_bit(TTY_THROTTLED, &tty->flags);
90 * pty_space - report space left for writing
91 * @to: tty we are writing into
93 * Limit the buffer space used by ptys to 8k.
96 static int pty_space(struct tty_struct *to)
98 int n = tty_buffer_space_avail(to->port);
103 * pty_write - write to a pty
104 * @tty: the tty we write from
105 * @buf: kernel buffer of data
106 * @count: bytes to write
108 * Our "hardware" write method. Data is coming from the ldisc which
109 * may be in a non sleeping state. We simply throw this at the other
110 * end of the link as if we were an IRQ handler receiving stuff for
111 * the other side of the pty/tty pair.
114 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
116 struct tty_struct *to = tty->link;
122 /* Stuff the data into the input queue of the other end */
123 c = tty_insert_flip_string(to->port, buf, c);
126 tty_flip_buffer_push(to->port);
132 * pty_write_room - write space
133 * @tty: tty we are writing from
135 * Report how many bytes the ldisc can send into the queue for
139 static int pty_write_room(struct tty_struct *tty)
143 return pty_space(tty->link);
147 * pty_chars_in_buffer - characters currently in our tx queue
150 * Report how much we have in the transmit queue. As everything is
151 * instantly at the other end this is easy to implement.
154 static int pty_chars_in_buffer(struct tty_struct *tty)
159 /* Set the lock flag on a pty */
160 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
163 if (get_user(val, arg))
166 set_bit(TTY_PTY_LOCK, &tty->flags);
168 clear_bit(TTY_PTY_LOCK, &tty->flags);
172 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
174 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
175 return put_user(locked, arg);
178 /* Set the packet mode on a pty */
179 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
184 if (get_user(pktmode, arg))
187 spin_lock_irqsave(&tty->ctrl_lock, flags);
191 tty->link->ctrl_status = 0;
195 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
200 /* Get the packet mode of a pty */
201 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
203 int pktmode = tty->packet;
204 return put_user(pktmode, arg);
207 /* Send a signal to the slave */
208 static int pty_signal(struct tty_struct *tty, int sig)
213 pgrp = tty_get_pgrp(tty->link);
215 kill_pgrp(pgrp, sig, 1);
221 static void pty_flush_buffer(struct tty_struct *tty)
223 struct tty_struct *to = tty->link;
228 /* tty_buffer_flush(to); FIXME */
230 spin_lock_irqsave(&tty->ctrl_lock, flags);
231 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
232 wake_up_interruptible(&to->read_wait);
233 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
237 static int pty_open(struct tty_struct *tty, struct file *filp)
239 if (!tty || !tty->link)
242 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
244 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
246 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
249 clear_bit(TTY_IO_ERROR, &tty->flags);
250 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
251 set_bit(TTY_THROTTLED, &tty->flags);
255 set_bit(TTY_IO_ERROR, &tty->flags);
259 static void pty_set_termios(struct tty_struct *tty,
260 struct ktermios *old_termios)
262 tty->termios.c_cflag &= ~(CSIZE | PARENB);
263 tty->termios.c_cflag |= (CS8 | CREAD);
267 * pty_do_resize - resize event
268 * @tty: tty being resized
269 * @ws: window size being set.
271 * Update the termios variables and send the necessary signals to
272 * peform a terminal resize correctly
275 static int pty_resize(struct tty_struct *tty, struct winsize *ws)
277 struct pid *pgrp, *rpgrp;
278 struct tty_struct *pty = tty->link;
280 /* For a PTY we need to lock the tty side */
281 mutex_lock(&tty->winsize_mutex);
282 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
285 /* Signal the foreground process group of both ptys */
286 pgrp = tty_get_pgrp(tty);
287 rpgrp = tty_get_pgrp(pty);
290 kill_pgrp(pgrp, SIGWINCH, 1);
291 if (rpgrp != pgrp && rpgrp)
292 kill_pgrp(rpgrp, SIGWINCH, 1);
298 pty->winsize = *ws; /* Never used so will go away soon */
300 mutex_unlock(&tty->winsize_mutex);
305 * pty_start - start() handler
306 * pty_stop - stop() handler
307 * @tty: tty being flow-controlled
309 * Propagates the TIOCPKT status to the master pty.
311 * NB: only the master pty can be in packet mode so only the slave
312 * needs start()/stop() handlers
314 static void pty_start(struct tty_struct *tty)
318 spin_lock_irqsave(&tty->ctrl_lock, flags);
319 if (tty->link && tty->link->packet) {
320 tty->ctrl_status &= ~TIOCPKT_STOP;
321 tty->ctrl_status |= TIOCPKT_START;
322 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
324 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
327 static void pty_stop(struct tty_struct *tty)
331 spin_lock_irqsave(&tty->ctrl_lock, flags);
332 if (tty->link && tty->link->packet) {
333 tty->ctrl_status &= ~TIOCPKT_START;
334 tty->ctrl_status |= TIOCPKT_STOP;
335 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
337 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
341 * pty_common_install - set up the pty pair
342 * @driver: the pty driver
343 * @tty: the tty being instantiated
344 * @legacy: true if this is BSD style
346 * Perform the initial set up for the tty/pty pair. Called from the
347 * tty layer when the port is first opened.
349 * Locking: the caller must hold the tty_mutex
351 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
354 struct tty_struct *o_tty;
355 struct tty_port *ports[2];
356 int idx = tty->index;
357 int retval = -ENOMEM;
359 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
360 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
361 if (!ports[0] || !ports[1])
363 if (!try_module_get(driver->other->owner)) {
364 /* This cannot in fact currently happen */
367 o_tty = alloc_tty_struct(driver->other, idx);
372 /* We always use new tty termios data so we can do this
374 retval = tty_init_termios(tty);
378 retval = tty_init_termios(o_tty);
380 goto err_free_termios;
382 driver->other->ttys[idx] = o_tty;
383 driver->ttys[idx] = tty;
385 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
386 tty->termios = driver->init_termios;
387 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
388 o_tty->termios = driver->other->init_termios;
392 * Everything allocated ... set up the o_tty structure.
394 tty_driver_kref_get(driver->other);
395 if (driver->subtype == PTY_TYPE_MASTER)
397 /* Establish the links in both directions */
400 tty_port_init(ports[0]);
401 tty_port_init(ports[1]);
402 o_tty->port = ports[0];
403 tty->port = ports[1];
404 o_tty->port->itty = o_tty;
406 tty_driver_kref_get(driver);
411 tty_free_termios(tty);
413 deinitialize_tty_struct(o_tty);
414 free_tty_struct(o_tty);
416 module_put(driver->other->owner);
423 static void pty_cleanup(struct tty_struct *tty)
425 tty_port_put(tty->port);
428 /* Traditional BSD devices */
429 #ifdef CONFIG_LEGACY_PTYS
431 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
433 return pty_common_install(driver, tty, true);
436 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
438 struct tty_struct *pair = tty->link;
439 driver->ttys[tty->index] = NULL;
441 pair->driver->ttys[pair->index] = NULL;
444 static int pty_bsd_ioctl(struct tty_struct *tty,
445 unsigned int cmd, unsigned long arg)
448 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
449 return pty_set_lock(tty, (int __user *) arg);
450 case TIOCGPTLCK: /* Get PT Lock status */
451 return pty_get_lock(tty, (int __user *)arg);
452 case TIOCPKT: /* Set PT packet mode */
453 return pty_set_pktmode(tty, (int __user *)arg);
454 case TIOCGPKT: /* Get PT packet mode */
455 return pty_get_pktmode(tty, (int __user *)arg);
456 case TIOCSIG: /* Send signal to other side of pty */
457 return pty_signal(tty, (int) arg);
458 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
464 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
465 module_param(legacy_count, int, 0);
468 * The master side of a pty can do TIOCSPTLCK and thus
471 static const struct tty_operations master_pty_ops_bsd = {
472 .install = pty_install,
476 .write_room = pty_write_room,
477 .flush_buffer = pty_flush_buffer,
478 .chars_in_buffer = pty_chars_in_buffer,
479 .unthrottle = pty_unthrottle,
480 .set_termios = pty_set_termios,
481 .ioctl = pty_bsd_ioctl,
482 .cleanup = pty_cleanup,
483 .resize = pty_resize,
487 static const struct tty_operations slave_pty_ops_bsd = {
488 .install = pty_install,
492 .write_room = pty_write_room,
493 .flush_buffer = pty_flush_buffer,
494 .chars_in_buffer = pty_chars_in_buffer,
495 .unthrottle = pty_unthrottle,
496 .set_termios = pty_set_termios,
497 .cleanup = pty_cleanup,
498 .resize = pty_resize,
504 static void __init legacy_pty_init(void)
506 struct tty_driver *pty_driver, *pty_slave_driver;
508 if (legacy_count <= 0)
511 pty_driver = tty_alloc_driver(legacy_count,
512 TTY_DRIVER_RESET_TERMIOS |
513 TTY_DRIVER_REAL_RAW |
514 TTY_DRIVER_DYNAMIC_ALLOC);
515 if (IS_ERR(pty_driver))
516 panic("Couldn't allocate pty driver");
518 pty_slave_driver = tty_alloc_driver(legacy_count,
519 TTY_DRIVER_RESET_TERMIOS |
520 TTY_DRIVER_REAL_RAW |
521 TTY_DRIVER_DYNAMIC_ALLOC);
522 if (IS_ERR(pty_slave_driver))
523 panic("Couldn't allocate pty slave driver");
525 pty_driver->driver_name = "pty_master";
526 pty_driver->name = "pty";
527 pty_driver->major = PTY_MASTER_MAJOR;
528 pty_driver->minor_start = 0;
529 pty_driver->type = TTY_DRIVER_TYPE_PTY;
530 pty_driver->subtype = PTY_TYPE_MASTER;
531 pty_driver->init_termios = tty_std_termios;
532 pty_driver->init_termios.c_iflag = 0;
533 pty_driver->init_termios.c_oflag = 0;
534 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
535 pty_driver->init_termios.c_lflag = 0;
536 pty_driver->init_termios.c_ispeed = 38400;
537 pty_driver->init_termios.c_ospeed = 38400;
538 pty_driver->other = pty_slave_driver;
539 tty_set_operations(pty_driver, &master_pty_ops_bsd);
541 pty_slave_driver->driver_name = "pty_slave";
542 pty_slave_driver->name = "ttyp";
543 pty_slave_driver->major = PTY_SLAVE_MAJOR;
544 pty_slave_driver->minor_start = 0;
545 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
546 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
547 pty_slave_driver->init_termios = tty_std_termios;
548 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
549 pty_slave_driver->init_termios.c_ispeed = 38400;
550 pty_slave_driver->init_termios.c_ospeed = 38400;
551 pty_slave_driver->other = pty_driver;
552 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
554 if (tty_register_driver(pty_driver))
555 panic("Couldn't register pty driver");
556 if (tty_register_driver(pty_slave_driver))
557 panic("Couldn't register pty slave driver");
560 static inline void legacy_pty_init(void) { }
564 #ifdef CONFIG_UNIX98_PTYS
566 static struct cdev ptmx_cdev;
568 static int pty_unix98_ioctl(struct tty_struct *tty,
569 unsigned int cmd, unsigned long arg)
572 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
573 return pty_set_lock(tty, (int __user *)arg);
574 case TIOCGPTLCK: /* Get PT Lock status */
575 return pty_get_lock(tty, (int __user *)arg);
576 case TIOCPKT: /* Set PT packet mode */
577 return pty_set_pktmode(tty, (int __user *)arg);
578 case TIOCGPKT: /* Get PT packet mode */
579 return pty_get_pktmode(tty, (int __user *)arg);
580 case TIOCGPTN: /* Get PT Number */
581 return put_user(tty->index, (unsigned int __user *)arg);
582 case TIOCSIG: /* Send signal to other side of pty */
583 return pty_signal(tty, (int) arg);
590 * ptm_unix98_lookup - find a pty master
591 * @driver: ptm driver
594 * Look up a pty master device. Called under the tty_mutex for now.
595 * This provides our locking.
598 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
599 struct inode *ptm_inode, int idx)
601 /* Master must be open via /dev/ptmx */
602 return ERR_PTR(-EIO);
606 * pts_unix98_lookup - find a pty slave
607 * @driver: pts driver
610 * Look up a pty master device. Called under the tty_mutex for now.
611 * This provides our locking for the tty pointer.
614 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
615 struct inode *pts_inode, int idx)
617 struct tty_struct *tty;
619 mutex_lock(&devpts_mutex);
620 tty = devpts_get_priv(pts_inode);
621 mutex_unlock(&devpts_mutex);
622 /* Master must be open before slave */
624 return ERR_PTR(-EIO);
628 /* We have no need to install and remove our tty objects as devpts does all
631 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
633 return pty_common_install(driver, tty, false);
636 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
640 /* this is called once with whichever end is closed last */
641 static void pty_unix98_shutdown(struct tty_struct *tty)
643 devpts_kill_index(tty->driver_data, tty->index);
646 static const struct tty_operations ptm_unix98_ops = {
647 .lookup = ptm_unix98_lookup,
648 .install = pty_unix98_install,
649 .remove = pty_unix98_remove,
653 .write_room = pty_write_room,
654 .flush_buffer = pty_flush_buffer,
655 .chars_in_buffer = pty_chars_in_buffer,
656 .unthrottle = pty_unthrottle,
657 .set_termios = pty_set_termios,
658 .ioctl = pty_unix98_ioctl,
659 .resize = pty_resize,
660 .shutdown = pty_unix98_shutdown,
661 .cleanup = pty_cleanup
664 static const struct tty_operations pty_unix98_ops = {
665 .lookup = pts_unix98_lookup,
666 .install = pty_unix98_install,
667 .remove = pty_unix98_remove,
671 .write_room = pty_write_room,
672 .flush_buffer = pty_flush_buffer,
673 .chars_in_buffer = pty_chars_in_buffer,
674 .unthrottle = pty_unthrottle,
675 .set_termios = pty_set_termios,
678 .shutdown = pty_unix98_shutdown,
679 .cleanup = pty_cleanup,
683 * ptmx_open - open a unix 98 pty master
684 * @inode: inode of device file
685 * @filp: file pointer to tty
687 * Allocate a unix98 pty master device from the ptmx driver.
689 * Locking: tty_mutex protects the init_dev work. tty->count should
691 * allocated_ptys_lock handles the list of free pty numbers
694 static int ptmx_open(struct inode *inode, struct file *filp)
696 struct tty_struct *tty;
697 struct inode *slave_inode;
701 nonseekable_open(inode, filp);
703 /* We refuse fsnotify events on ptmx, since it's a shared resource */
704 filp->f_mode |= FMODE_NONOTIFY;
706 retval = tty_alloc_file(filp);
710 /* find a device that is not in use. */
711 mutex_lock(&devpts_mutex);
712 index = devpts_new_index(inode);
715 mutex_unlock(&devpts_mutex);
719 mutex_unlock(&devpts_mutex);
721 mutex_lock(&tty_mutex);
722 tty = tty_init_dev(ptm_driver, index);
725 retval = PTR_ERR(tty);
729 /* The tty returned here is locked so we can safely
731 mutex_unlock(&tty_mutex);
733 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
734 tty->driver_data = inode;
736 tty_add_file(tty, filp);
738 slave_inode = devpts_pty_new(inode,
739 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
741 if (IS_ERR(slave_inode)) {
742 retval = PTR_ERR(slave_inode);
745 tty->link->driver_data = slave_inode;
747 retval = ptm_driver->ops->open(tty, filp);
755 tty_release(inode, filp);
758 mutex_unlock(&tty_mutex);
759 devpts_kill_index(inode, index);
765 static struct file_operations ptmx_fops;
767 static void __init unix98_pty_init(void)
769 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
770 TTY_DRIVER_RESET_TERMIOS |
771 TTY_DRIVER_REAL_RAW |
772 TTY_DRIVER_DYNAMIC_DEV |
773 TTY_DRIVER_DEVPTS_MEM |
774 TTY_DRIVER_DYNAMIC_ALLOC);
775 if (IS_ERR(ptm_driver))
776 panic("Couldn't allocate Unix98 ptm driver");
777 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
778 TTY_DRIVER_RESET_TERMIOS |
779 TTY_DRIVER_REAL_RAW |
780 TTY_DRIVER_DYNAMIC_DEV |
781 TTY_DRIVER_DEVPTS_MEM |
782 TTY_DRIVER_DYNAMIC_ALLOC);
783 if (IS_ERR(pts_driver))
784 panic("Couldn't allocate Unix98 pts driver");
786 ptm_driver->driver_name = "pty_master";
787 ptm_driver->name = "ptm";
788 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
789 ptm_driver->minor_start = 0;
790 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
791 ptm_driver->subtype = PTY_TYPE_MASTER;
792 ptm_driver->init_termios = tty_std_termios;
793 ptm_driver->init_termios.c_iflag = 0;
794 ptm_driver->init_termios.c_oflag = 0;
795 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
796 ptm_driver->init_termios.c_lflag = 0;
797 ptm_driver->init_termios.c_ispeed = 38400;
798 ptm_driver->init_termios.c_ospeed = 38400;
799 ptm_driver->other = pts_driver;
800 tty_set_operations(ptm_driver, &ptm_unix98_ops);
802 pts_driver->driver_name = "pty_slave";
803 pts_driver->name = "pts";
804 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
805 pts_driver->minor_start = 0;
806 pts_driver->type = TTY_DRIVER_TYPE_PTY;
807 pts_driver->subtype = PTY_TYPE_SLAVE;
808 pts_driver->init_termios = tty_std_termios;
809 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
810 pts_driver->init_termios.c_ispeed = 38400;
811 pts_driver->init_termios.c_ospeed = 38400;
812 pts_driver->other = ptm_driver;
813 tty_set_operations(pts_driver, &pty_unix98_ops);
815 if (tty_register_driver(ptm_driver))
816 panic("Couldn't register Unix98 ptm driver");
817 if (tty_register_driver(pts_driver))
818 panic("Couldn't register Unix98 pts driver");
820 /* Now create the /dev/ptmx special device */
821 tty_default_fops(&ptmx_fops);
822 ptmx_fops.open = ptmx_open;
824 cdev_init(&ptmx_cdev, &ptmx_fops);
825 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
826 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
827 panic("Couldn't register /dev/ptmx driver");
828 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
832 static inline void unix98_pty_init(void) { }
835 static int __init pty_init(void)
841 module_init(pty_init);