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->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 /* Send a signal to the slave */
175 static int pty_signal(struct tty_struct *tty, int sig)
181 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
182 pgrp = get_pid(tty->link->pgrp);
183 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
185 kill_pgrp(pgrp, sig, 1);
191 static void pty_flush_buffer(struct tty_struct *tty)
193 struct tty_struct *to = tty->link;
198 /* tty_buffer_flush(to); FIXME */
200 spin_lock_irqsave(&tty->ctrl_lock, flags);
201 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
202 wake_up_interruptible(&to->read_wait);
203 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
207 static int pty_open(struct tty_struct *tty, struct file *filp)
209 int retval = -ENODEV;
211 if (!tty || !tty->link)
215 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
217 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
219 if (tty->link->count != 1)
222 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
223 set_bit(TTY_THROTTLED, &tty->flags);
229 static void pty_set_termios(struct tty_struct *tty,
230 struct ktermios *old_termios)
232 tty->termios.c_cflag &= ~(CSIZE | PARENB);
233 tty->termios.c_cflag |= (CS8 | CREAD);
237 * pty_do_resize - resize event
238 * @tty: tty being resized
239 * @ws: window size being set.
241 * Update the termios variables and send the necessary signals to
242 * peform a terminal resize correctly
245 int pty_resize(struct tty_struct *tty, struct winsize *ws)
247 struct pid *pgrp, *rpgrp;
249 struct tty_struct *pty = tty->link;
251 /* For a PTY we need to lock the tty side */
252 mutex_lock(&tty->termios_mutex);
253 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
256 /* Get the PID values and reference them so we can
257 avoid holding the tty ctrl lock while sending signals.
258 We need to lock these individually however. */
260 spin_lock_irqsave(&tty->ctrl_lock, flags);
261 pgrp = get_pid(tty->pgrp);
262 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
264 spin_lock_irqsave(&pty->ctrl_lock, flags);
265 rpgrp = get_pid(pty->pgrp);
266 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
269 kill_pgrp(pgrp, SIGWINCH, 1);
270 if (rpgrp != pgrp && rpgrp)
271 kill_pgrp(rpgrp, SIGWINCH, 1);
277 pty->winsize = *ws; /* Never used so will go away soon */
279 mutex_unlock(&tty->termios_mutex);
284 * pty_common_install - set up the pty pair
285 * @driver: the pty driver
286 * @tty: the tty being instantiated
287 * @bool: legacy, true if this is BSD style
289 * Perform the initial set up for the tty/pty pair. Called from the
290 * tty layer when the port is first opened.
292 * Locking: the caller must hold the tty_mutex
294 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
297 struct tty_struct *o_tty;
298 struct tty_port *ports[2];
299 int idx = tty->index;
300 int retval = -ENOMEM;
302 o_tty = alloc_tty_struct();
305 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
306 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
307 if (!ports[0] || !ports[1])
309 if (!try_module_get(driver->other->owner)) {
310 /* This cannot in fact currently happen */
313 initialize_tty_struct(o_tty, driver->other, idx);
316 /* We always use new tty termios data so we can do this
318 retval = tty_init_termios(tty);
322 retval = tty_init_termios(o_tty);
324 goto err_free_termios;
326 driver->other->ttys[idx] = o_tty;
327 driver->ttys[idx] = tty;
329 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
330 tty->termios = driver->init_termios;
331 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
332 o_tty->termios = driver->other->init_termios;
336 * Everything allocated ... set up the o_tty structure.
338 tty_driver_kref_get(driver->other);
339 if (driver->subtype == PTY_TYPE_MASTER)
341 /* Establish the links in both directions */
344 tty_port_init(ports[0]);
345 tty_port_init(ports[1]);
346 o_tty->port = ports[0];
347 tty->port = ports[1];
348 o_tty->port->itty = o_tty;
350 tty_driver_kref_get(driver);
355 tty_free_termios(tty);
357 deinitialize_tty_struct(o_tty);
358 module_put(o_tty->driver->owner);
362 free_tty_struct(o_tty);
367 /* this is called once with whichever end is closed last */
368 static void pty_unix98_shutdown(struct tty_struct *tty)
370 devpts_kill_index(tty->driver_data, tty->index);
373 static void pty_cleanup(struct tty_struct *tty)
375 tty->port->itty = NULL;
379 /* Traditional BSD devices */
380 #ifdef CONFIG_LEGACY_PTYS
382 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
384 return pty_common_install(driver, tty, true);
387 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
389 struct tty_struct *pair = tty->link;
390 driver->ttys[tty->index] = NULL;
392 pair->driver->ttys[pair->index] = NULL;
395 static int pty_bsd_ioctl(struct tty_struct *tty,
396 unsigned int cmd, unsigned long arg)
399 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
400 return pty_set_lock(tty, (int __user *) arg);
401 case TIOCSIG: /* Send signal to other side of pty */
402 return pty_signal(tty, (int) arg);
407 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
408 module_param(legacy_count, int, 0);
411 * The master side of a pty can do TIOCSPTLCK and thus
414 static const struct tty_operations master_pty_ops_bsd = {
415 .install = pty_install,
419 .write_room = pty_write_room,
420 .flush_buffer = pty_flush_buffer,
421 .chars_in_buffer = pty_chars_in_buffer,
422 .unthrottle = pty_unthrottle,
423 .set_termios = pty_set_termios,
424 .ioctl = pty_bsd_ioctl,
425 .cleanup = pty_cleanup,
426 .resize = pty_resize,
430 static const struct tty_operations slave_pty_ops_bsd = {
431 .install = pty_install,
435 .write_room = pty_write_room,
436 .flush_buffer = pty_flush_buffer,
437 .chars_in_buffer = pty_chars_in_buffer,
438 .unthrottle = pty_unthrottle,
439 .set_termios = pty_set_termios,
440 .cleanup = pty_cleanup,
441 .resize = pty_resize,
445 static void __init legacy_pty_init(void)
447 struct tty_driver *pty_driver, *pty_slave_driver;
449 if (legacy_count <= 0)
452 pty_driver = tty_alloc_driver(legacy_count,
453 TTY_DRIVER_RESET_TERMIOS |
454 TTY_DRIVER_REAL_RAW |
455 TTY_DRIVER_DYNAMIC_ALLOC);
456 if (IS_ERR(pty_driver))
457 panic("Couldn't allocate pty driver");
459 pty_slave_driver = tty_alloc_driver(legacy_count,
460 TTY_DRIVER_RESET_TERMIOS |
461 TTY_DRIVER_REAL_RAW |
462 TTY_DRIVER_DYNAMIC_ALLOC);
463 if (IS_ERR(pty_slave_driver))
464 panic("Couldn't allocate pty slave driver");
466 pty_driver->driver_name = "pty_master";
467 pty_driver->name = "pty";
468 pty_driver->major = PTY_MASTER_MAJOR;
469 pty_driver->minor_start = 0;
470 pty_driver->type = TTY_DRIVER_TYPE_PTY;
471 pty_driver->subtype = PTY_TYPE_MASTER;
472 pty_driver->init_termios = tty_std_termios;
473 pty_driver->init_termios.c_iflag = 0;
474 pty_driver->init_termios.c_oflag = 0;
475 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
476 pty_driver->init_termios.c_lflag = 0;
477 pty_driver->init_termios.c_ispeed = 38400;
478 pty_driver->init_termios.c_ospeed = 38400;
479 pty_driver->other = pty_slave_driver;
480 tty_set_operations(pty_driver, &master_pty_ops_bsd);
482 pty_slave_driver->driver_name = "pty_slave";
483 pty_slave_driver->name = "ttyp";
484 pty_slave_driver->major = PTY_SLAVE_MAJOR;
485 pty_slave_driver->minor_start = 0;
486 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
487 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
488 pty_slave_driver->init_termios = tty_std_termios;
489 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
490 pty_slave_driver->init_termios.c_ispeed = 38400;
491 pty_slave_driver->init_termios.c_ospeed = 38400;
492 pty_slave_driver->other = pty_driver;
493 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
495 if (tty_register_driver(pty_driver))
496 panic("Couldn't register pty driver");
497 if (tty_register_driver(pty_slave_driver))
498 panic("Couldn't register pty slave driver");
501 static inline void legacy_pty_init(void) { }
505 #ifdef CONFIG_UNIX98_PTYS
507 static struct cdev ptmx_cdev;
509 static int pty_unix98_ioctl(struct tty_struct *tty,
510 unsigned int cmd, unsigned long arg)
513 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
514 return pty_set_lock(tty, (int __user *)arg);
515 case TIOCGPTN: /* Get PT Number */
516 return put_user(tty->index, (unsigned int __user *)arg);
517 case TIOCSIG: /* Send signal to other side of pty */
518 return pty_signal(tty, (int) arg);
525 * ptm_unix98_lookup - find a pty master
526 * @driver: ptm driver
529 * Look up a pty master device. Called under the tty_mutex for now.
530 * This provides our locking.
533 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
534 struct inode *ptm_inode, int idx)
536 /* Master must be open via /dev/ptmx */
537 return ERR_PTR(-EIO);
541 * pts_unix98_lookup - find a pty slave
542 * @driver: pts driver
545 * Look up a pty master device. Called under the tty_mutex for now.
546 * This provides our locking for the tty pointer.
549 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
550 struct inode *pts_inode, int idx)
552 struct tty_struct *tty;
554 mutex_lock(&devpts_mutex);
555 tty = devpts_get_priv(pts_inode);
556 mutex_unlock(&devpts_mutex);
557 /* Master must be open before slave */
559 return ERR_PTR(-EIO);
563 /* We have no need to install and remove our tty objects as devpts does all
566 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
568 return pty_common_install(driver, tty, false);
571 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
575 static const struct tty_operations ptm_unix98_ops = {
576 .lookup = ptm_unix98_lookup,
577 .install = pty_unix98_install,
578 .remove = pty_unix98_remove,
582 .write_room = pty_write_room,
583 .flush_buffer = pty_flush_buffer,
584 .chars_in_buffer = pty_chars_in_buffer,
585 .unthrottle = pty_unthrottle,
586 .set_termios = pty_set_termios,
587 .ioctl = pty_unix98_ioctl,
588 .resize = pty_resize,
589 .shutdown = pty_unix98_shutdown,
590 .cleanup = pty_cleanup
593 static const struct tty_operations pty_unix98_ops = {
594 .lookup = pts_unix98_lookup,
595 .install = pty_unix98_install,
596 .remove = pty_unix98_remove,
600 .write_room = pty_write_room,
601 .flush_buffer = pty_flush_buffer,
602 .chars_in_buffer = pty_chars_in_buffer,
603 .unthrottle = pty_unthrottle,
604 .set_termios = pty_set_termios,
605 .shutdown = pty_unix98_shutdown,
606 .cleanup = pty_cleanup,
610 * ptmx_open - open a unix 98 pty master
611 * @inode: inode of device file
612 * @filp: file pointer to tty
614 * Allocate a unix98 pty master device from the ptmx driver.
616 * Locking: tty_mutex protects the init_dev work. tty->count should
618 * allocated_ptys_lock handles the list of free pty numbers
621 static int ptmx_open(struct inode *inode, struct file *filp)
623 struct tty_struct *tty;
624 struct inode *slave_inode;
628 nonseekable_open(inode, filp);
630 retval = tty_alloc_file(filp);
634 /* find a device that is not in use. */
635 mutex_lock(&devpts_mutex);
636 index = devpts_new_index(inode);
639 mutex_unlock(&devpts_mutex);
643 mutex_unlock(&devpts_mutex);
645 mutex_lock(&tty_mutex);
646 tty = tty_init_dev(ptm_driver, index);
649 retval = PTR_ERR(tty);
653 /* The tty returned here is locked so we can safely
655 mutex_unlock(&tty_mutex);
657 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
659 tty_add_file(tty, filp);
661 slave_inode = devpts_pty_new(inode,
662 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
664 if (IS_ERR(slave_inode)) {
665 retval = PTR_ERR(slave_inode);
669 retval = ptm_driver->ops->open(tty, filp);
674 tty->driver_data = inode;
675 tty->link->driver_data = slave_inode;
679 tty_release(inode, filp);
682 mutex_unlock(&tty_mutex);
683 devpts_kill_index(inode, index);
689 static struct file_operations ptmx_fops;
691 static void __init unix98_pty_init(void)
693 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
694 TTY_DRIVER_RESET_TERMIOS |
695 TTY_DRIVER_REAL_RAW |
696 TTY_DRIVER_DYNAMIC_DEV |
697 TTY_DRIVER_DEVPTS_MEM |
698 TTY_DRIVER_DYNAMIC_ALLOC);
699 if (IS_ERR(ptm_driver))
700 panic("Couldn't allocate Unix98 ptm driver");
701 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
702 TTY_DRIVER_RESET_TERMIOS |
703 TTY_DRIVER_REAL_RAW |
704 TTY_DRIVER_DYNAMIC_DEV |
705 TTY_DRIVER_DEVPTS_MEM |
706 TTY_DRIVER_DYNAMIC_ALLOC);
707 if (IS_ERR(pts_driver))
708 panic("Couldn't allocate Unix98 pts driver");
710 ptm_driver->driver_name = "pty_master";
711 ptm_driver->name = "ptm";
712 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
713 ptm_driver->minor_start = 0;
714 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
715 ptm_driver->subtype = PTY_TYPE_MASTER;
716 ptm_driver->init_termios = tty_std_termios;
717 ptm_driver->init_termios.c_iflag = 0;
718 ptm_driver->init_termios.c_oflag = 0;
719 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
720 ptm_driver->init_termios.c_lflag = 0;
721 ptm_driver->init_termios.c_ispeed = 38400;
722 ptm_driver->init_termios.c_ospeed = 38400;
723 ptm_driver->other = pts_driver;
724 tty_set_operations(ptm_driver, &ptm_unix98_ops);
726 pts_driver->driver_name = "pty_slave";
727 pts_driver->name = "pts";
728 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
729 pts_driver->minor_start = 0;
730 pts_driver->type = TTY_DRIVER_TYPE_PTY;
731 pts_driver->subtype = PTY_TYPE_SLAVE;
732 pts_driver->init_termios = tty_std_termios;
733 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
734 pts_driver->init_termios.c_ispeed = 38400;
735 pts_driver->init_termios.c_ospeed = 38400;
736 pts_driver->other = ptm_driver;
737 tty_set_operations(pts_driver, &pty_unix98_ops);
739 if (tty_register_driver(ptm_driver))
740 panic("Couldn't register Unix98 ptm driver");
741 if (tty_register_driver(pts_driver))
742 panic("Couldn't register Unix98 pts driver");
744 /* Now create the /dev/ptmx special device */
745 tty_default_fops(&ptmx_fops);
746 ptmx_fops.open = ptmx_open;
748 cdev_init(&ptmx_cdev, &ptmx_fops);
749 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
750 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
751 panic("Couldn't register /dev/ptmx driver\n");
752 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
756 static inline void unix98_pty_init(void) { }
759 static int __init pty_init(void)
765 module_init(pty_init);