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>
30 #include <asm/system.h>
32 #ifdef CONFIG_UNIX98_PTYS
33 static struct tty_driver *ptm_driver;
34 static struct tty_driver *pts_driver;
37 static void pty_close(struct tty_struct *tty, struct file *filp)
40 if (tty->driver->subtype == PTY_TYPE_MASTER)
41 WARN_ON(tty->count > 1);
46 wake_up_interruptible(&tty->read_wait);
47 wake_up_interruptible(&tty->write_wait);
51 tty->link->packet = 0;
52 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
53 wake_up_interruptible(&tty->link->read_wait);
54 wake_up_interruptible(&tty->link->write_wait);
55 if (tty->driver->subtype == PTY_TYPE_MASTER) {
56 set_bit(TTY_OTHER_CLOSED, &tty->flags);
57 #ifdef CONFIG_UNIX98_PTYS
58 if (tty->driver == ptm_driver)
59 devpts_pty_kill(tty->link);
62 tty_vhangup(tty->link);
68 * The unthrottle routine is called by the line discipline to signal
69 * that it can receive more characters. For PTY's, the TTY_THROTTLED
70 * flag is always set, to force the line discipline to always call the
71 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
72 * characters in the queue. This is necessary since each time this
73 * happens, we need to wake up any sleeping processes that could be
74 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
75 * for the pty buffer to be drained.
77 static void pty_unthrottle(struct tty_struct *tty)
79 tty_wakeup(tty->link);
80 set_bit(TTY_THROTTLED, &tty->flags);
84 * pty_space - report space left for writing
85 * @to: tty we are writing into
87 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
88 * allows a lot of overspill room for echo and other fun messes to
92 static int pty_space(struct tty_struct *to)
94 int n = 8192 - to->buf.memory_used;
101 * pty_write - write to a pty
102 * @tty: the tty we write from
103 * @buf: kernel buffer of data
104 * @count: bytes to write
106 * Our "hardware" write method. Data is coming from the ldisc which
107 * may be in a non sleeping state. We simply throw this at the other
108 * end of the link as if we were an IRQ handler receiving stuff for
109 * the other side of the pty/tty pair.
112 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
114 struct tty_struct *to = tty->link;
120 /* Stuff the data into the input queue of the other end */
121 c = tty_insert_flip_string(to, buf, c);
124 tty_flip_buffer_push(to);
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 /* Send a signal to the slave */
173 static int pty_signal(struct tty_struct *tty, int sig)
179 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
180 pgrp = get_pid(tty->link->pgrp);
181 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
183 kill_pgrp(pgrp, sig, 1);
189 static void pty_flush_buffer(struct tty_struct *tty)
191 struct tty_struct *to = tty->link;
196 /* tty_buffer_flush(to); FIXME */
198 spin_lock_irqsave(&tty->ctrl_lock, flags);
199 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
200 wake_up_interruptible(&to->read_wait);
201 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
205 static int pty_open(struct tty_struct *tty, struct file *filp)
207 int retval = -ENODEV;
209 if (!tty || !tty->link)
213 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
215 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
217 if (tty->link->count != 1)
220 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
221 set_bit(TTY_THROTTLED, &tty->flags);
227 static void pty_set_termios(struct tty_struct *tty,
228 struct ktermios *old_termios)
230 tty->termios->c_cflag &= ~(CSIZE | PARENB);
231 tty->termios->c_cflag |= (CS8 | CREAD);
235 * pty_do_resize - resize event
236 * @tty: tty being resized
237 * @ws: window size being set.
239 * Update the termios variables and send the necessary signals to
240 * peform a terminal resize correctly
243 int pty_resize(struct tty_struct *tty, struct winsize *ws)
245 struct pid *pgrp, *rpgrp;
247 struct tty_struct *pty = tty->link;
249 /* For a PTY we need to lock the tty side */
250 mutex_lock(&tty->termios_mutex);
251 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
254 /* Get the PID values and reference them so we can
255 avoid holding the tty ctrl lock while sending signals.
256 We need to lock these individually however. */
258 spin_lock_irqsave(&tty->ctrl_lock, flags);
259 pgrp = get_pid(tty->pgrp);
260 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
262 spin_lock_irqsave(&pty->ctrl_lock, flags);
263 rpgrp = get_pid(pty->pgrp);
264 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
267 kill_pgrp(pgrp, SIGWINCH, 1);
268 if (rpgrp != pgrp && rpgrp)
269 kill_pgrp(rpgrp, SIGWINCH, 1);
275 pty->winsize = *ws; /* Never used so will go away soon */
277 mutex_unlock(&tty->termios_mutex);
281 /* Traditional BSD devices */
282 #ifdef CONFIG_LEGACY_PTYS
284 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
286 struct tty_struct *o_tty;
287 int idx = tty->index;
290 o_tty = alloc_tty_struct();
293 if (!try_module_get(driver->other->owner)) {
294 /* This cannot in fact currently happen */
298 initialize_tty_struct(o_tty, driver->other, idx);
300 /* We always use new tty termios data so we can do this
302 retval = tty_init_termios(tty);
306 retval = tty_init_termios(o_tty);
308 goto err_free_termios;
311 * Everything allocated ... set up the o_tty structure.
313 driver->other->ttys[idx] = o_tty;
314 tty_driver_kref_get(driver->other);
315 if (driver->subtype == PTY_TYPE_MASTER)
317 /* Establish the links in both directions */
321 tty_driver_kref_get(driver);
323 driver->ttys[idx] = tty;
326 tty_free_termios(tty);
328 deinitialize_tty_struct(o_tty);
329 module_put(o_tty->driver->owner);
331 free_tty_struct(o_tty);
335 static int pty_bsd_ioctl(struct tty_struct *tty,
336 unsigned int cmd, unsigned long arg)
339 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
340 return pty_set_lock(tty, (int __user *) arg);
341 case TIOCSIG: /* Send signal to other side of pty */
342 return pty_signal(tty, (int) arg);
347 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
348 module_param(legacy_count, int, 0);
351 * The master side of a pty can do TIOCSPTLCK and thus
354 static const struct tty_operations master_pty_ops_bsd = {
355 .install = pty_install,
359 .write_room = pty_write_room,
360 .flush_buffer = pty_flush_buffer,
361 .chars_in_buffer = pty_chars_in_buffer,
362 .unthrottle = pty_unthrottle,
363 .set_termios = pty_set_termios,
364 .ioctl = pty_bsd_ioctl,
368 static const struct tty_operations slave_pty_ops_bsd = {
369 .install = pty_install,
373 .write_room = pty_write_room,
374 .flush_buffer = pty_flush_buffer,
375 .chars_in_buffer = pty_chars_in_buffer,
376 .unthrottle = pty_unthrottle,
377 .set_termios = pty_set_termios,
381 static void __init legacy_pty_init(void)
383 struct tty_driver *pty_driver, *pty_slave_driver;
385 if (legacy_count <= 0)
388 pty_driver = alloc_tty_driver(legacy_count);
390 panic("Couldn't allocate pty driver");
392 pty_slave_driver = alloc_tty_driver(legacy_count);
393 if (!pty_slave_driver)
394 panic("Couldn't allocate pty slave driver");
396 pty_driver->driver_name = "pty_master";
397 pty_driver->name = "pty";
398 pty_driver->major = PTY_MASTER_MAJOR;
399 pty_driver->minor_start = 0;
400 pty_driver->type = TTY_DRIVER_TYPE_PTY;
401 pty_driver->subtype = PTY_TYPE_MASTER;
402 pty_driver->init_termios = tty_std_termios;
403 pty_driver->init_termios.c_iflag = 0;
404 pty_driver->init_termios.c_oflag = 0;
405 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
406 pty_driver->init_termios.c_lflag = 0;
407 pty_driver->init_termios.c_ispeed = 38400;
408 pty_driver->init_termios.c_ospeed = 38400;
409 pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
410 pty_driver->other = pty_slave_driver;
411 tty_set_operations(pty_driver, &master_pty_ops_bsd);
413 pty_slave_driver->driver_name = "pty_slave";
414 pty_slave_driver->name = "ttyp";
415 pty_slave_driver->major = PTY_SLAVE_MAJOR;
416 pty_slave_driver->minor_start = 0;
417 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
418 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
419 pty_slave_driver->init_termios = tty_std_termios;
420 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
421 pty_slave_driver->init_termios.c_ispeed = 38400;
422 pty_slave_driver->init_termios.c_ospeed = 38400;
423 pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
425 pty_slave_driver->other = pty_driver;
426 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
428 if (tty_register_driver(pty_driver))
429 panic("Couldn't register pty driver");
430 if (tty_register_driver(pty_slave_driver))
431 panic("Couldn't register pty slave driver");
434 static inline void legacy_pty_init(void) { }
438 #ifdef CONFIG_UNIX98_PTYS
440 static struct cdev ptmx_cdev;
442 static int pty_unix98_ioctl(struct tty_struct *tty,
443 unsigned int cmd, unsigned long arg)
446 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
447 return pty_set_lock(tty, (int __user *)arg);
448 case TIOCGPTN: /* Get PT Number */
449 return put_user(tty->index, (unsigned int __user *)arg);
450 case TIOCSIG: /* Send signal to other side of pty */
451 return pty_signal(tty, (int) arg);
458 * ptm_unix98_lookup - find a pty master
459 * @driver: ptm driver
462 * Look up a pty master device. Called under the tty_mutex for now.
463 * This provides our locking.
466 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
467 struct inode *ptm_inode, int idx)
469 /* Master must be open via /dev/ptmx */
470 return ERR_PTR(-EIO);
474 * pts_unix98_lookup - find a pty slave
475 * @driver: pts driver
478 * Look up a pty master device. Called under the tty_mutex for now.
479 * This provides our locking.
482 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
483 struct inode *pts_inode, int idx)
485 struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
486 /* Master must be open before slave */
488 return ERR_PTR(-EIO);
492 static void pty_unix98_shutdown(struct tty_struct *tty)
494 tty_driver_remove_tty(tty->driver, tty);
495 /* We have our own method as we don't use the tty index */
499 /* We have no need to install and remove our tty objects as devpts does all
502 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
504 struct tty_struct *o_tty;
505 int idx = tty->index;
507 o_tty = alloc_tty_struct();
510 if (!try_module_get(driver->other->owner)) {
511 /* This cannot in fact currently happen */
514 initialize_tty_struct(o_tty, driver->other, idx);
516 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
517 if (tty->termios == NULL)
519 *tty->termios = driver->init_termios;
520 tty->termios_locked = tty->termios + 1;
522 o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
523 if (o_tty->termios == NULL)
525 *o_tty->termios = driver->other->init_termios;
526 o_tty->termios_locked = o_tty->termios + 1;
528 tty_driver_kref_get(driver->other);
529 if (driver->subtype == PTY_TYPE_MASTER)
531 /* Establish the links in both directions */
535 * All structures have been allocated, so now we install them.
536 * Failures after this point use release_tty to clean up, so
537 * there's no need to null out the local pointers.
539 tty_driver_kref_get(driver);
543 deinitialize_tty_struct(o_tty);
544 kfree(o_tty->termios);
546 module_put(o_tty->driver->owner);
548 free_tty_struct(o_tty);
552 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
556 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
560 static const struct tty_operations ptm_unix98_ops = {
561 .lookup = ptm_unix98_lookup,
562 .install = pty_unix98_install,
563 .remove = ptm_unix98_remove,
567 .write_room = pty_write_room,
568 .flush_buffer = pty_flush_buffer,
569 .chars_in_buffer = pty_chars_in_buffer,
570 .unthrottle = pty_unthrottle,
571 .set_termios = pty_set_termios,
572 .ioctl = pty_unix98_ioctl,
573 .shutdown = pty_unix98_shutdown,
577 static const struct tty_operations pty_unix98_ops = {
578 .lookup = pts_unix98_lookup,
579 .install = pty_unix98_install,
580 .remove = pts_unix98_remove,
584 .write_room = pty_write_room,
585 .flush_buffer = pty_flush_buffer,
586 .chars_in_buffer = pty_chars_in_buffer,
587 .unthrottle = pty_unthrottle,
588 .set_termios = pty_set_termios,
589 .shutdown = pty_unix98_shutdown
593 * ptmx_open - open a unix 98 pty master
594 * @inode: inode of device file
595 * @filp: file pointer to tty
597 * Allocate a unix98 pty master device from the ptmx driver.
599 * Locking: tty_mutex protects the init_dev work. tty->count should
601 * allocated_ptys_lock handles the list of free pty numbers
604 static int ptmx_open(struct inode *inode, struct file *filp)
606 struct tty_struct *tty;
610 nonseekable_open(inode, filp);
612 retval = tty_alloc_file(filp);
616 /* find a device that is not in use. */
618 index = devpts_new_index(inode);
625 mutex_lock(&tty_mutex);
627 tty = tty_init_dev(ptm_driver, index);
628 mutex_unlock(&tty_mutex);
631 retval = PTR_ERR(tty);
635 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
637 tty_add_file(tty, filp);
639 retval = devpts_pty_new(inode, tty->link);
643 retval = ptm_driver->ops->open(tty, filp);
651 tty_release(inode, filp);
654 devpts_kill_index(inode, index);
661 static struct file_operations ptmx_fops;
663 static void __init unix98_pty_init(void)
665 ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
667 panic("Couldn't allocate Unix98 ptm driver");
668 pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
670 panic("Couldn't allocate Unix98 pts driver");
672 ptm_driver->driver_name = "pty_master";
673 ptm_driver->name = "ptm";
674 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
675 ptm_driver->minor_start = 0;
676 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
677 ptm_driver->subtype = PTY_TYPE_MASTER;
678 ptm_driver->init_termios = tty_std_termios;
679 ptm_driver->init_termios.c_iflag = 0;
680 ptm_driver->init_termios.c_oflag = 0;
681 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
682 ptm_driver->init_termios.c_lflag = 0;
683 ptm_driver->init_termios.c_ispeed = 38400;
684 ptm_driver->init_termios.c_ospeed = 38400;
685 ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
686 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
687 ptm_driver->other = pts_driver;
688 tty_set_operations(ptm_driver, &ptm_unix98_ops);
690 pts_driver->driver_name = "pty_slave";
691 pts_driver->name = "pts";
692 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
693 pts_driver->minor_start = 0;
694 pts_driver->type = TTY_DRIVER_TYPE_PTY;
695 pts_driver->subtype = PTY_TYPE_SLAVE;
696 pts_driver->init_termios = tty_std_termios;
697 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
698 pts_driver->init_termios.c_ispeed = 38400;
699 pts_driver->init_termios.c_ospeed = 38400;
700 pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
701 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
702 pts_driver->other = ptm_driver;
703 tty_set_operations(pts_driver, &pty_unix98_ops);
705 if (tty_register_driver(ptm_driver))
706 panic("Couldn't register Unix98 ptm driver");
707 if (tty_register_driver(pts_driver))
708 panic("Couldn't register Unix98 pts driver");
710 /* Now create the /dev/ptmx special device */
711 tty_default_fops(&ptmx_fops);
712 ptmx_fops.open = ptmx_open;
714 cdev_init(&ptmx_cdev, &ptmx_fops);
715 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
716 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
717 panic("Couldn't register /dev/ptmx driver\n");
718 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
722 static inline void unix98_pty_init(void) { }
725 static int __init pty_init(void)
731 module_init(pty_init);