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];
349 tty_driver_kref_get(driver);
354 tty_free_termios(tty);
356 deinitialize_tty_struct(o_tty);
357 module_put(o_tty->driver->owner);
361 free_tty_struct(o_tty);
366 static void pty_cleanup(struct tty_struct *tty)
371 /* Traditional BSD devices */
372 #ifdef CONFIG_LEGACY_PTYS
374 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
376 return pty_common_install(driver, tty, true);
379 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
381 struct tty_struct *pair = tty->link;
382 driver->ttys[tty->index] = NULL;
384 pair->driver->ttys[pair->index] = NULL;
387 static int pty_bsd_ioctl(struct tty_struct *tty,
388 unsigned int cmd, unsigned long arg)
391 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
392 return pty_set_lock(tty, (int __user *) arg);
393 case TIOCSIG: /* Send signal to other side of pty */
394 return pty_signal(tty, (int) arg);
399 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
400 module_param(legacy_count, int, 0);
403 * The master side of a pty can do TIOCSPTLCK and thus
406 static const struct tty_operations master_pty_ops_bsd = {
407 .install = pty_install,
411 .write_room = pty_write_room,
412 .flush_buffer = pty_flush_buffer,
413 .chars_in_buffer = pty_chars_in_buffer,
414 .unthrottle = pty_unthrottle,
415 .set_termios = pty_set_termios,
416 .ioctl = pty_bsd_ioctl,
417 .cleanup = pty_cleanup,
418 .resize = pty_resize,
422 static const struct tty_operations slave_pty_ops_bsd = {
423 .install = pty_install,
427 .write_room = pty_write_room,
428 .flush_buffer = pty_flush_buffer,
429 .chars_in_buffer = pty_chars_in_buffer,
430 .unthrottle = pty_unthrottle,
431 .set_termios = pty_set_termios,
432 .cleanup = pty_cleanup,
433 .resize = pty_resize,
437 static void __init legacy_pty_init(void)
439 struct tty_driver *pty_driver, *pty_slave_driver;
441 if (legacy_count <= 0)
444 pty_driver = tty_alloc_driver(legacy_count,
445 TTY_DRIVER_RESET_TERMIOS |
446 TTY_DRIVER_REAL_RAW |
447 TTY_DRIVER_DYNAMIC_ALLOC);
448 if (IS_ERR(pty_driver))
449 panic("Couldn't allocate pty driver");
451 pty_slave_driver = tty_alloc_driver(legacy_count,
452 TTY_DRIVER_RESET_TERMIOS |
453 TTY_DRIVER_REAL_RAW |
454 TTY_DRIVER_DYNAMIC_ALLOC);
455 if (IS_ERR(pty_slave_driver))
456 panic("Couldn't allocate pty slave driver");
458 pty_driver->driver_name = "pty_master";
459 pty_driver->name = "pty";
460 pty_driver->major = PTY_MASTER_MAJOR;
461 pty_driver->minor_start = 0;
462 pty_driver->type = TTY_DRIVER_TYPE_PTY;
463 pty_driver->subtype = PTY_TYPE_MASTER;
464 pty_driver->init_termios = tty_std_termios;
465 pty_driver->init_termios.c_iflag = 0;
466 pty_driver->init_termios.c_oflag = 0;
467 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
468 pty_driver->init_termios.c_lflag = 0;
469 pty_driver->init_termios.c_ispeed = 38400;
470 pty_driver->init_termios.c_ospeed = 38400;
471 pty_driver->other = pty_slave_driver;
472 tty_set_operations(pty_driver, &master_pty_ops_bsd);
474 pty_slave_driver->driver_name = "pty_slave";
475 pty_slave_driver->name = "ttyp";
476 pty_slave_driver->major = PTY_SLAVE_MAJOR;
477 pty_slave_driver->minor_start = 0;
478 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
479 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
480 pty_slave_driver->init_termios = tty_std_termios;
481 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
482 pty_slave_driver->init_termios.c_ispeed = 38400;
483 pty_slave_driver->init_termios.c_ospeed = 38400;
484 pty_slave_driver->other = pty_driver;
485 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
487 if (tty_register_driver(pty_driver))
488 panic("Couldn't register pty driver");
489 if (tty_register_driver(pty_slave_driver))
490 panic("Couldn't register pty slave driver");
493 static inline void legacy_pty_init(void) { }
497 #ifdef CONFIG_UNIX98_PTYS
499 static struct cdev ptmx_cdev;
501 static int pty_unix98_ioctl(struct tty_struct *tty,
502 unsigned int cmd, unsigned long arg)
505 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
506 return pty_set_lock(tty, (int __user *)arg);
507 case TIOCGPTN: /* Get PT Number */
508 return put_user(tty->index, (unsigned int __user *)arg);
509 case TIOCSIG: /* Send signal to other side of pty */
510 return pty_signal(tty, (int) arg);
517 * ptm_unix98_lookup - find a pty master
518 * @driver: ptm driver
521 * Look up a pty master device. Called under the tty_mutex for now.
522 * This provides our locking.
525 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
526 struct inode *ptm_inode, int idx)
528 /* Master must be open via /dev/ptmx */
529 return ERR_PTR(-EIO);
533 * pts_unix98_lookup - find a pty slave
534 * @driver: pts driver
537 * Look up a pty master device. Called under the tty_mutex for now.
538 * This provides our locking for the tty pointer.
541 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
542 struct inode *pts_inode, int idx)
544 struct tty_struct *tty;
546 mutex_lock(&devpts_mutex);
547 tty = devpts_get_priv(pts_inode);
548 mutex_unlock(&devpts_mutex);
549 /* Master must be open before slave */
551 return ERR_PTR(-EIO);
555 /* We have no need to install and remove our tty objects as devpts does all
558 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
560 return pty_common_install(driver, tty, false);
563 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
567 static const struct tty_operations ptm_unix98_ops = {
568 .lookup = ptm_unix98_lookup,
569 .install = pty_unix98_install,
570 .remove = pty_unix98_remove,
574 .write_room = pty_write_room,
575 .flush_buffer = pty_flush_buffer,
576 .chars_in_buffer = pty_chars_in_buffer,
577 .unthrottle = pty_unthrottle,
578 .set_termios = pty_set_termios,
579 .ioctl = pty_unix98_ioctl,
580 .resize = pty_resize,
581 .cleanup = pty_cleanup
584 static const struct tty_operations pty_unix98_ops = {
585 .lookup = pts_unix98_lookup,
586 .install = pty_unix98_install,
587 .remove = pty_unix98_remove,
591 .write_room = pty_write_room,
592 .flush_buffer = pty_flush_buffer,
593 .chars_in_buffer = pty_chars_in_buffer,
594 .unthrottle = pty_unthrottle,
595 .set_termios = pty_set_termios,
596 .cleanup = pty_cleanup,
600 * ptmx_open - open a unix 98 pty master
601 * @inode: inode of device file
602 * @filp: file pointer to tty
604 * Allocate a unix98 pty master device from the ptmx driver.
606 * Locking: tty_mutex protects the init_dev work. tty->count should
608 * allocated_ptys_lock handles the list of free pty numbers
611 static int ptmx_open(struct inode *inode, struct file *filp)
613 struct tty_struct *tty;
614 struct inode *slave_inode;
618 nonseekable_open(inode, filp);
620 retval = tty_alloc_file(filp);
624 /* find a device that is not in use. */
625 mutex_lock(&devpts_mutex);
626 index = devpts_new_index(inode);
629 mutex_unlock(&devpts_mutex);
633 mutex_unlock(&devpts_mutex);
635 mutex_lock(&tty_mutex);
636 tty = tty_init_dev(ptm_driver, index);
639 retval = PTR_ERR(tty);
643 /* The tty returned here is locked so we can safely
645 mutex_unlock(&tty_mutex);
647 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
649 tty_add_file(tty, filp);
651 slave_inode = devpts_pty_new(inode,
652 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
654 if (IS_ERR(slave_inode)) {
655 retval = PTR_ERR(slave_inode);
659 retval = ptm_driver->ops->open(tty, filp);
664 tty->link->driver_data = slave_inode;
668 tty_release(inode, filp);
671 mutex_unlock(&tty_mutex);
672 devpts_kill_index(inode, index);
678 static struct file_operations ptmx_fops;
680 static void __init unix98_pty_init(void)
682 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
683 TTY_DRIVER_RESET_TERMIOS |
684 TTY_DRIVER_REAL_RAW |
685 TTY_DRIVER_DYNAMIC_DEV |
686 TTY_DRIVER_DEVPTS_MEM |
687 TTY_DRIVER_DYNAMIC_ALLOC);
688 if (IS_ERR(ptm_driver))
689 panic("Couldn't allocate Unix98 ptm driver");
690 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
691 TTY_DRIVER_RESET_TERMIOS |
692 TTY_DRIVER_REAL_RAW |
693 TTY_DRIVER_DYNAMIC_DEV |
694 TTY_DRIVER_DEVPTS_MEM |
695 TTY_DRIVER_DYNAMIC_ALLOC);
696 if (IS_ERR(pts_driver))
697 panic("Couldn't allocate Unix98 pts driver");
699 ptm_driver->driver_name = "pty_master";
700 ptm_driver->name = "ptm";
701 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
702 ptm_driver->minor_start = 0;
703 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
704 ptm_driver->subtype = PTY_TYPE_MASTER;
705 ptm_driver->init_termios = tty_std_termios;
706 ptm_driver->init_termios.c_iflag = 0;
707 ptm_driver->init_termios.c_oflag = 0;
708 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
709 ptm_driver->init_termios.c_lflag = 0;
710 ptm_driver->init_termios.c_ispeed = 38400;
711 ptm_driver->init_termios.c_ospeed = 38400;
712 ptm_driver->other = pts_driver;
713 tty_set_operations(ptm_driver, &ptm_unix98_ops);
715 pts_driver->driver_name = "pty_slave";
716 pts_driver->name = "pts";
717 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
718 pts_driver->minor_start = 0;
719 pts_driver->type = TTY_DRIVER_TYPE_PTY;
720 pts_driver->subtype = PTY_TYPE_SLAVE;
721 pts_driver->init_termios = tty_std_termios;
722 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
723 pts_driver->init_termios.c_ispeed = 38400;
724 pts_driver->init_termios.c_ospeed = 38400;
725 pts_driver->other = ptm_driver;
726 tty_set_operations(pts_driver, &pty_unix98_ops);
728 if (tty_register_driver(ptm_driver))
729 panic("Couldn't register Unix98 ptm driver");
730 if (tty_register_driver(pts_driver))
731 panic("Couldn't register Unix98 pts driver");
733 /* Now create the /dev/ptmx special device */
734 tty_default_fops(&ptmx_fops);
735 ptmx_fops.open = ptmx_open;
737 cdev_init(&ptmx_cdev, &ptmx_fops);
738 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
739 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
740 panic("Couldn't register /dev/ptmx driver\n");
741 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
745 static inline void unix98_pty_init(void) { }
748 static int __init pty_init(void)
754 module_init(pty_init);