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>
29 #ifdef CONFIG_UNIX98_PTYS
30 static struct tty_driver *ptm_driver;
31 static struct tty_driver *pts_driver;
32 static DEFINE_MUTEX(devpts_mutex);
35 static void pty_close(struct tty_struct *tty, struct file *filp)
38 if (tty->driver->subtype == PTY_TYPE_MASTER)
39 WARN_ON(tty->count > 1);
44 wake_up_interruptible(&tty->read_wait);
45 wake_up_interruptible(&tty->write_wait);
47 /* Review - krefs on tty_link ?? */
50 tty->link->packet = 0;
51 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
52 wake_up_interruptible(&tty->link->read_wait);
53 wake_up_interruptible(&tty->link->write_wait);
54 if (tty->driver->subtype == PTY_TYPE_MASTER) {
55 set_bit(TTY_OTHER_CLOSED, &tty->flags);
56 #ifdef CONFIG_UNIX98_PTYS
57 if (tty->driver == ptm_driver) {
58 mutex_lock(&devpts_mutex);
59 devpts_pty_kill(tty->link->driver_data);
60 mutex_unlock(&devpts_mutex);
64 tty_vhangup(tty->link);
70 * The unthrottle routine is called by the line discipline to signal
71 * that it can receive more characters. For PTY's, the TTY_THROTTLED
72 * flag is always set, to force the line discipline to always call the
73 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
74 * characters in the queue. This is necessary since each time this
75 * happens, we need to wake up any sleeping processes that could be
76 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
77 * for the pty buffer to be drained.
79 static void pty_unthrottle(struct tty_struct *tty)
81 tty_wakeup(tty->link);
82 set_bit(TTY_THROTTLED, &tty->flags);
86 * pty_space - report space left for writing
87 * @to: tty we are writing into
89 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
90 * allows a lot of overspill room for echo and other fun messes to
94 static int pty_space(struct tty_struct *to)
96 int n = 8192 - to->port->buf.memory_used;
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, buf, c);
126 tty_flip_buffer_push(to);
134 * pty_write_room - write space
135 * @tty: tty we are writing from
137 * Report how many bytes the ldisc can send into the queue for
141 static int pty_write_room(struct tty_struct *tty)
145 return pty_space(tty->link);
149 * pty_chars_in_buffer - characters currently in our tx queue
152 * Report how much we have in the transmit queue. As everything is
153 * instantly at the other end this is easy to implement.
156 static int pty_chars_in_buffer(struct tty_struct *tty)
161 /* Set the lock flag on a pty */
162 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
165 if (get_user(val, arg))
168 set_bit(TTY_PTY_LOCK, &tty->flags);
170 clear_bit(TTY_PTY_LOCK, &tty->flags);
174 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
176 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
177 return put_user(locked, arg);
180 /* Set the packet mode on a pty */
181 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
186 if (get_user(pktmode, arg))
189 spin_lock_irqsave(&tty->ctrl_lock, flags);
193 tty->link->ctrl_status = 0;
197 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
202 /* Get the packet mode of a pty */
203 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
205 int pktmode = tty->packet;
206 return put_user(pktmode, arg);
209 /* Send a signal to the slave */
210 static int pty_signal(struct tty_struct *tty, int sig)
216 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
217 pgrp = get_pid(tty->link->pgrp);
218 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
220 kill_pgrp(pgrp, sig, 1);
226 static void pty_flush_buffer(struct tty_struct *tty)
228 struct tty_struct *to = tty->link;
233 /* tty_buffer_flush(to); FIXME */
235 spin_lock_irqsave(&tty->ctrl_lock, flags);
236 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
237 wake_up_interruptible(&to->read_wait);
238 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
242 static int pty_open(struct tty_struct *tty, struct file *filp)
244 int retval = -ENODEV;
246 if (!tty || !tty->link)
250 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
252 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
254 if (tty->link->count != 1)
257 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
258 set_bit(TTY_THROTTLED, &tty->flags);
264 static void pty_set_termios(struct tty_struct *tty,
265 struct ktermios *old_termios)
267 tty->termios.c_cflag &= ~(CSIZE | PARENB);
268 tty->termios.c_cflag |= (CS8 | CREAD);
272 * pty_do_resize - resize event
273 * @tty: tty being resized
274 * @ws: window size being set.
276 * Update the termios variables and send the necessary signals to
277 * peform a terminal resize correctly
280 int pty_resize(struct tty_struct *tty, struct winsize *ws)
282 struct pid *pgrp, *rpgrp;
284 struct tty_struct *pty = tty->link;
286 /* For a PTY we need to lock the tty side */
287 mutex_lock(&tty->termios_mutex);
288 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
291 /* Get the PID values and reference them so we can
292 avoid holding the tty ctrl lock while sending signals.
293 We need to lock these individually however. */
295 spin_lock_irqsave(&tty->ctrl_lock, flags);
296 pgrp = get_pid(tty->pgrp);
297 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
299 spin_lock_irqsave(&pty->ctrl_lock, flags);
300 rpgrp = get_pid(pty->pgrp);
301 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
304 kill_pgrp(pgrp, SIGWINCH, 1);
305 if (rpgrp != pgrp && rpgrp)
306 kill_pgrp(rpgrp, SIGWINCH, 1);
312 pty->winsize = *ws; /* Never used so will go away soon */
314 mutex_unlock(&tty->termios_mutex);
319 * pty_common_install - set up the pty pair
320 * @driver: the pty driver
321 * @tty: the tty being instantiated
322 * @bool: legacy, true if this is BSD style
324 * Perform the initial set up for the tty/pty pair. Called from the
325 * tty layer when the port is first opened.
327 * Locking: the caller must hold the tty_mutex
329 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
332 struct tty_struct *o_tty;
333 struct tty_port *ports[2];
334 int idx = tty->index;
335 int retval = -ENOMEM;
337 o_tty = alloc_tty_struct();
340 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
341 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
342 if (!ports[0] || !ports[1])
344 if (!try_module_get(driver->other->owner)) {
345 /* This cannot in fact currently happen */
348 initialize_tty_struct(o_tty, driver->other, idx);
351 /* We always use new tty termios data so we can do this
353 retval = tty_init_termios(tty);
357 retval = tty_init_termios(o_tty);
359 goto err_free_termios;
361 driver->other->ttys[idx] = o_tty;
362 driver->ttys[idx] = tty;
364 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
365 tty->termios = driver->init_termios;
366 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
367 o_tty->termios = driver->other->init_termios;
371 * Everything allocated ... set up the o_tty structure.
373 tty_driver_kref_get(driver->other);
374 if (driver->subtype == PTY_TYPE_MASTER)
376 /* Establish the links in both directions */
379 tty_port_init(ports[0]);
380 tty_port_init(ports[1]);
381 o_tty->port = ports[0];
382 tty->port = ports[1];
383 o_tty->port->itty = o_tty;
385 tty_driver_kref_get(driver);
390 tty_free_termios(tty);
392 deinitialize_tty_struct(o_tty);
393 module_put(o_tty->driver->owner);
397 free_tty_struct(o_tty);
402 /* this is called once with whichever end is closed last */
403 static void pty_unix98_shutdown(struct tty_struct *tty)
405 devpts_kill_index(tty->driver_data, tty->index);
408 static void pty_cleanup(struct tty_struct *tty)
410 tty->port->itty = NULL;
411 tty_port_put(tty->port);
414 /* Traditional BSD devices */
415 #ifdef CONFIG_LEGACY_PTYS
417 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
419 return pty_common_install(driver, tty, true);
422 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
424 struct tty_struct *pair = tty->link;
425 driver->ttys[tty->index] = NULL;
427 pair->driver->ttys[pair->index] = NULL;
430 static int pty_bsd_ioctl(struct tty_struct *tty,
431 unsigned int cmd, unsigned long arg)
434 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
435 return pty_set_lock(tty, (int __user *) arg);
436 case TIOCGPTLCK: /* Get PT Lock status */
437 return pty_get_lock(tty, (int __user *)arg);
438 case TIOCPKT: /* Set PT packet mode */
439 return pty_set_pktmode(tty, (int __user *)arg);
440 case TIOCGPKT: /* Get PT packet mode */
441 return pty_get_pktmode(tty, (int __user *)arg);
442 case TIOCSIG: /* Send signal to other side of pty */
443 return pty_signal(tty, (int) arg);
448 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
449 module_param(legacy_count, int, 0);
452 * The master side of a pty can do TIOCSPTLCK and thus
455 static const struct tty_operations master_pty_ops_bsd = {
456 .install = pty_install,
460 .write_room = pty_write_room,
461 .flush_buffer = pty_flush_buffer,
462 .chars_in_buffer = pty_chars_in_buffer,
463 .unthrottle = pty_unthrottle,
464 .set_termios = pty_set_termios,
465 .ioctl = pty_bsd_ioctl,
466 .cleanup = pty_cleanup,
467 .resize = pty_resize,
471 static const struct tty_operations slave_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 .cleanup = pty_cleanup,
482 .resize = pty_resize,
486 static void __init legacy_pty_init(void)
488 struct tty_driver *pty_driver, *pty_slave_driver;
490 if (legacy_count <= 0)
493 pty_driver = tty_alloc_driver(legacy_count,
494 TTY_DRIVER_RESET_TERMIOS |
495 TTY_DRIVER_REAL_RAW |
496 TTY_DRIVER_DYNAMIC_ALLOC);
497 if (IS_ERR(pty_driver))
498 panic("Couldn't allocate pty driver");
500 pty_slave_driver = tty_alloc_driver(legacy_count,
501 TTY_DRIVER_RESET_TERMIOS |
502 TTY_DRIVER_REAL_RAW |
503 TTY_DRIVER_DYNAMIC_ALLOC);
504 if (IS_ERR(pty_slave_driver))
505 panic("Couldn't allocate pty slave driver");
507 pty_driver->driver_name = "pty_master";
508 pty_driver->name = "pty";
509 pty_driver->major = PTY_MASTER_MAJOR;
510 pty_driver->minor_start = 0;
511 pty_driver->type = TTY_DRIVER_TYPE_PTY;
512 pty_driver->subtype = PTY_TYPE_MASTER;
513 pty_driver->init_termios = tty_std_termios;
514 pty_driver->init_termios.c_iflag = 0;
515 pty_driver->init_termios.c_oflag = 0;
516 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
517 pty_driver->init_termios.c_lflag = 0;
518 pty_driver->init_termios.c_ispeed = 38400;
519 pty_driver->init_termios.c_ospeed = 38400;
520 pty_driver->other = pty_slave_driver;
521 tty_set_operations(pty_driver, &master_pty_ops_bsd);
523 pty_slave_driver->driver_name = "pty_slave";
524 pty_slave_driver->name = "ttyp";
525 pty_slave_driver->major = PTY_SLAVE_MAJOR;
526 pty_slave_driver->minor_start = 0;
527 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
528 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
529 pty_slave_driver->init_termios = tty_std_termios;
530 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
531 pty_slave_driver->init_termios.c_ispeed = 38400;
532 pty_slave_driver->init_termios.c_ospeed = 38400;
533 pty_slave_driver->other = pty_driver;
534 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
536 if (tty_register_driver(pty_driver))
537 panic("Couldn't register pty driver");
538 if (tty_register_driver(pty_slave_driver))
539 panic("Couldn't register pty slave driver");
542 static inline void legacy_pty_init(void) { }
546 #ifdef CONFIG_UNIX98_PTYS
548 static struct cdev ptmx_cdev;
550 static int pty_unix98_ioctl(struct tty_struct *tty,
551 unsigned int cmd, unsigned long arg)
554 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
555 return pty_set_lock(tty, (int __user *)arg);
556 case TIOCGPTLCK: /* Get PT Lock status */
557 return pty_get_lock(tty, (int __user *)arg);
558 case TIOCPKT: /* Set PT packet mode */
559 return pty_set_pktmode(tty, (int __user *)arg);
560 case TIOCGPKT: /* Get PT packet mode */
561 return pty_get_pktmode(tty, (int __user *)arg);
562 case TIOCGPTN: /* Get PT Number */
563 return put_user(tty->index, (unsigned int __user *)arg);
564 case TIOCSIG: /* Send signal to other side of pty */
565 return pty_signal(tty, (int) arg);
572 * ptm_unix98_lookup - find a pty master
573 * @driver: ptm driver
576 * Look up a pty master device. Called under the tty_mutex for now.
577 * This provides our locking.
580 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
581 struct inode *ptm_inode, int idx)
583 /* Master must be open via /dev/ptmx */
584 return ERR_PTR(-EIO);
588 * pts_unix98_lookup - find a pty slave
589 * @driver: pts driver
592 * Look up a pty master device. Called under the tty_mutex for now.
593 * This provides our locking for the tty pointer.
596 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
597 struct inode *pts_inode, int idx)
599 struct tty_struct *tty;
601 mutex_lock(&devpts_mutex);
602 tty = devpts_get_priv(pts_inode);
603 mutex_unlock(&devpts_mutex);
604 /* Master must be open before slave */
606 return ERR_PTR(-EIO);
610 /* We have no need to install and remove our tty objects as devpts does all
613 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
615 return pty_common_install(driver, tty, false);
618 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
622 static const struct tty_operations ptm_unix98_ops = {
623 .lookup = ptm_unix98_lookup,
624 .install = pty_unix98_install,
625 .remove = pty_unix98_remove,
629 .write_room = pty_write_room,
630 .flush_buffer = pty_flush_buffer,
631 .chars_in_buffer = pty_chars_in_buffer,
632 .unthrottle = pty_unthrottle,
633 .set_termios = pty_set_termios,
634 .ioctl = pty_unix98_ioctl,
635 .resize = pty_resize,
636 .shutdown = pty_unix98_shutdown,
637 .cleanup = pty_cleanup
640 static const struct tty_operations pty_unix98_ops = {
641 .lookup = pts_unix98_lookup,
642 .install = pty_unix98_install,
643 .remove = pty_unix98_remove,
647 .write_room = pty_write_room,
648 .flush_buffer = pty_flush_buffer,
649 .chars_in_buffer = pty_chars_in_buffer,
650 .unthrottle = pty_unthrottle,
651 .set_termios = pty_set_termios,
652 .shutdown = pty_unix98_shutdown,
653 .cleanup = pty_cleanup,
657 * ptmx_open - open a unix 98 pty master
658 * @inode: inode of device file
659 * @filp: file pointer to tty
661 * Allocate a unix98 pty master device from the ptmx driver.
663 * Locking: tty_mutex protects the init_dev work. tty->count should
665 * allocated_ptys_lock handles the list of free pty numbers
668 static int ptmx_open(struct inode *inode, struct file *filp)
670 struct tty_struct *tty;
671 struct inode *slave_inode;
675 nonseekable_open(inode, filp);
677 retval = tty_alloc_file(filp);
681 /* find a device that is not in use. */
682 mutex_lock(&devpts_mutex);
683 index = devpts_new_index(inode);
686 mutex_unlock(&devpts_mutex);
690 mutex_unlock(&devpts_mutex);
692 mutex_lock(&tty_mutex);
693 tty = tty_init_dev(ptm_driver, index);
696 retval = PTR_ERR(tty);
700 /* The tty returned here is locked so we can safely
702 mutex_unlock(&tty_mutex);
704 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
706 tty_add_file(tty, filp);
708 slave_inode = devpts_pty_new(inode,
709 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
711 if (IS_ERR(slave_inode)) {
712 retval = PTR_ERR(slave_inode);
716 retval = ptm_driver->ops->open(tty, filp);
721 tty->driver_data = inode;
722 tty->link->driver_data = slave_inode;
726 tty_release(inode, filp);
729 mutex_unlock(&tty_mutex);
730 devpts_kill_index(inode, index);
736 static struct file_operations ptmx_fops;
738 static void __init unix98_pty_init(void)
740 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
741 TTY_DRIVER_RESET_TERMIOS |
742 TTY_DRIVER_REAL_RAW |
743 TTY_DRIVER_DYNAMIC_DEV |
744 TTY_DRIVER_DEVPTS_MEM |
745 TTY_DRIVER_DYNAMIC_ALLOC);
746 if (IS_ERR(ptm_driver))
747 panic("Couldn't allocate Unix98 ptm driver");
748 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
749 TTY_DRIVER_RESET_TERMIOS |
750 TTY_DRIVER_REAL_RAW |
751 TTY_DRIVER_DYNAMIC_DEV |
752 TTY_DRIVER_DEVPTS_MEM |
753 TTY_DRIVER_DYNAMIC_ALLOC);
754 if (IS_ERR(pts_driver))
755 panic("Couldn't allocate Unix98 pts driver");
757 ptm_driver->driver_name = "pty_master";
758 ptm_driver->name = "ptm";
759 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
760 ptm_driver->minor_start = 0;
761 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
762 ptm_driver->subtype = PTY_TYPE_MASTER;
763 ptm_driver->init_termios = tty_std_termios;
764 ptm_driver->init_termios.c_iflag = 0;
765 ptm_driver->init_termios.c_oflag = 0;
766 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
767 ptm_driver->init_termios.c_lflag = 0;
768 ptm_driver->init_termios.c_ispeed = 38400;
769 ptm_driver->init_termios.c_ospeed = 38400;
770 ptm_driver->other = pts_driver;
771 tty_set_operations(ptm_driver, &ptm_unix98_ops);
773 pts_driver->driver_name = "pty_slave";
774 pts_driver->name = "pts";
775 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
776 pts_driver->minor_start = 0;
777 pts_driver->type = TTY_DRIVER_TYPE_PTY;
778 pts_driver->subtype = PTY_TYPE_SLAVE;
779 pts_driver->init_termios = tty_std_termios;
780 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
781 pts_driver->init_termios.c_ispeed = 38400;
782 pts_driver->init_termios.c_ospeed = 38400;
783 pts_driver->other = ptm_driver;
784 tty_set_operations(pts_driver, &pty_unix98_ops);
786 if (tty_register_driver(ptm_driver))
787 panic("Couldn't register Unix98 ptm driver");
788 if (tty_register_driver(pts_driver))
789 panic("Couldn't register Unix98 pts driver");
791 /* Now create the /dev/ptmx special device */
792 tty_default_fops(&ptmx_fops);
793 ptmx_fops.open = ptmx_open;
795 cdev_init(&ptmx_cdev, &ptmx_fops);
796 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
797 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
798 panic("Couldn't register /dev/ptmx driver\n");
799 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
803 static inline void unix98_pty_init(void) { }
806 static int __init pty_init(void)
812 module_init(pty_init);