2 * linux/drivers/char/pty.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Added support for a Unix98-style ptmx device.
7 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
9 * When reading this code see also fs/devpts. In particular note that the
10 * driver_data field is used by the devpts side as a binding to the devpts
14 #include <linux/module.h>
16 #include <linux/errno.h>
17 #include <linux/interrupt.h>
18 #include <linux/tty.h>
19 #include <linux/tty_flip.h>
20 #include <linux/fcntl.h>
21 #include <linux/sched.h>
22 #include <linux/string.h>
23 #include <linux/major.h>
25 #include <linux/init.h>
26 #include <linux/smp_lock.h>
27 #include <linux/sysctl.h>
28 #include <linux/device.h>
29 #include <linux/uaccess.h>
30 #include <linux/bitops.h>
31 #include <linux/devpts_fs.h>
32 #include <linux/slab.h>
34 #include <asm/system.h>
36 #ifdef CONFIG_UNIX98_PTYS
37 static struct tty_driver
*ptm_driver
;
38 static struct tty_driver
*pts_driver
;
41 static void pty_close(struct tty_struct
*tty
, struct file
*filp
)
44 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
)
45 WARN_ON(tty
->count
> 1);
50 wake_up_interruptible(&tty
->read_wait
);
51 wake_up_interruptible(&tty
->write_wait
);
55 tty
->link
->packet
= 0;
56 set_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
57 wake_up_interruptible(&tty
->link
->read_wait
);
58 wake_up_interruptible(&tty
->link
->write_wait
);
59 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
) {
60 set_bit(TTY_OTHER_CLOSED
, &tty
->flags
);
61 #ifdef CONFIG_UNIX98_PTYS
62 if (tty
->driver
== ptm_driver
)
63 devpts_pty_kill(tty
->link
);
66 tty_vhangup(tty
->link
);
72 * The unthrottle routine is called by the line discipline to signal
73 * that it can receive more characters. For PTY's, the TTY_THROTTLED
74 * flag is always set, to force the line discipline to always call the
75 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
76 * characters in the queue. This is necessary since each time this
77 * happens, we need to wake up any sleeping processes that could be
78 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
79 * for the pty buffer to be drained.
81 static void pty_unthrottle(struct tty_struct
*tty
)
83 tty_wakeup(tty
->link
);
84 set_bit(TTY_THROTTLED
, &tty
->flags
);
88 * pty_space - report space left for writing
89 * @to: tty we are writing into
91 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
92 * allows a lot of overspill room for echo and other fun messes to
96 static int pty_space(struct tty_struct
*to
)
98 int n
= 8192 - to
->buf
.memory_used
;
105 * pty_write - write to a pty
106 * @tty: the tty we write from
107 * @buf: kernel buffer of data
108 * @count: bytes to write
110 * Our "hardware" write method. Data is coming from the ldisc which
111 * may be in a non sleeping state. We simply throw this at the other
112 * end of the link as if we were an IRQ handler receiving stuff for
113 * the other side of the pty/tty pair.
116 static int pty_write(struct tty_struct
*tty
, const unsigned char *buf
, int c
)
118 struct tty_struct
*to
= tty
->link
;
124 /* Stuff the data into the input queue of the other end */
125 c
= tty_insert_flip_string(to
, buf
, c
);
128 tty_flip_buffer_push(to
);
136 * pty_write_room - write space
137 * @tty: tty we are writing from
139 * Report how many bytes the ldisc can send into the queue for
143 static int pty_write_room(struct tty_struct
*tty
)
147 return pty_space(tty
->link
);
151 * pty_chars_in_buffer - characters currently in our tx queue
154 * Report how much we have in the transmit queue. As everything is
155 * instantly at the other end this is easy to implement.
158 static int pty_chars_in_buffer(struct tty_struct
*tty
)
163 /* Set the lock flag on a pty */
164 static int pty_set_lock(struct tty_struct
*tty
, int __user
*arg
)
167 if (get_user(val
, arg
))
170 set_bit(TTY_PTY_LOCK
, &tty
->flags
);
172 clear_bit(TTY_PTY_LOCK
, &tty
->flags
);
176 /* Send a signal to the slave */
177 static int pty_signal(struct tty_struct
*tty
, int sig
)
183 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
184 pgrp
= get_pid(tty
->link
->pgrp
);
185 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
187 kill_pgrp(pgrp
, sig
, 1);
193 static void pty_flush_buffer(struct tty_struct
*tty
)
195 struct tty_struct
*to
= tty
->link
;
200 /* tty_buffer_flush(to); FIXME */
202 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
203 tty
->ctrl_status
|= TIOCPKT_FLUSHWRITE
;
204 wake_up_interruptible(&to
->read_wait
);
205 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
209 static int pty_open(struct tty_struct
*tty
, struct file
*filp
)
211 int retval
= -ENODEV
;
213 if (!tty
|| !tty
->link
)
217 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
219 if (test_bit(TTY_PTY_LOCK
, &tty
->link
->flags
))
221 if (tty
->link
->count
!= 1)
224 clear_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
225 set_bit(TTY_THROTTLED
, &tty
->flags
);
231 static void pty_set_termios(struct tty_struct
*tty
,
232 struct ktermios
*old_termios
)
234 tty
->termios
->c_cflag
&= ~(CSIZE
| PARENB
);
235 tty
->termios
->c_cflag
|= (CS8
| CREAD
);
239 * pty_do_resize - resize event
240 * @tty: tty being resized
241 * @ws: window size being set.
243 * Update the termios variables and send the necessary signals to
244 * peform a terminal resize correctly
247 int pty_resize(struct tty_struct
*tty
, struct winsize
*ws
)
249 struct pid
*pgrp
, *rpgrp
;
251 struct tty_struct
*pty
= tty
->link
;
253 /* For a PTY we need to lock the tty side */
254 mutex_lock(&tty
->termios_mutex
);
255 if (!memcmp(ws
, &tty
->winsize
, sizeof(*ws
)))
258 /* Get the PID values and reference them so we can
259 avoid holding the tty ctrl lock while sending signals.
260 We need to lock these individually however. */
262 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
263 pgrp
= get_pid(tty
->pgrp
);
264 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
266 spin_lock_irqsave(&pty
->ctrl_lock
, flags
);
267 rpgrp
= get_pid(pty
->pgrp
);
268 spin_unlock_irqrestore(&pty
->ctrl_lock
, flags
);
271 kill_pgrp(pgrp
, SIGWINCH
, 1);
272 if (rpgrp
!= pgrp
&& rpgrp
)
273 kill_pgrp(rpgrp
, SIGWINCH
, 1);
279 pty
->winsize
= *ws
; /* Never used so will go away soon */
281 mutex_unlock(&tty
->termios_mutex
);
285 /* Traditional BSD devices */
286 #ifdef CONFIG_LEGACY_PTYS
288 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
290 struct tty_struct
*o_tty
;
291 int idx
= tty
->index
;
294 o_tty
= alloc_tty_struct();
297 if (!try_module_get(driver
->other
->owner
)) {
298 /* This cannot in fact currently happen */
299 free_tty_struct(o_tty
);
302 initialize_tty_struct(o_tty
, driver
->other
, idx
);
304 /* We always use new tty termios data so we can do this
306 retval
= tty_init_termios(tty
);
310 retval
= tty_init_termios(o_tty
);
312 tty_free_termios(tty
);
317 * Everything allocated ... set up the o_tty structure.
319 driver
->other
->ttys
[idx
] = o_tty
;
320 tty_driver_kref_get(driver
->other
);
321 if (driver
->subtype
== PTY_TYPE_MASTER
)
323 /* Establish the links in both directions */
327 tty_driver_kref_get(driver
);
329 driver
->ttys
[idx
] = tty
;
332 module_put(o_tty
->driver
->owner
);
333 free_tty_struct(o_tty
);
337 static int pty_bsd_ioctl(struct tty_struct
*tty
, struct file
*file
,
338 unsigned int cmd
, unsigned long arg
)
341 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
342 return pty_set_lock(tty
, (int __user
*) arg
);
343 case TIOCSIG
: /* Send signal to other side of pty */
344 return pty_signal(tty
, (int) arg
);
349 static int legacy_count
= CONFIG_LEGACY_PTY_COUNT
;
350 module_param(legacy_count
, int, 0);
353 * The master side of a pty can do TIOCSPTLCK and thus
356 static const struct tty_operations master_pty_ops_bsd
= {
357 .install
= pty_install
,
361 .write_room
= pty_write_room
,
362 .flush_buffer
= pty_flush_buffer
,
363 .chars_in_buffer
= pty_chars_in_buffer
,
364 .unthrottle
= pty_unthrottle
,
365 .set_termios
= pty_set_termios
,
366 .ioctl
= pty_bsd_ioctl
,
370 static const struct tty_operations slave_pty_ops_bsd
= {
371 .install
= pty_install
,
375 .write_room
= pty_write_room
,
376 .flush_buffer
= pty_flush_buffer
,
377 .chars_in_buffer
= pty_chars_in_buffer
,
378 .unthrottle
= pty_unthrottle
,
379 .set_termios
= pty_set_termios
,
383 static void __init
legacy_pty_init(void)
385 struct tty_driver
*pty_driver
, *pty_slave_driver
;
387 if (legacy_count
<= 0)
390 pty_driver
= alloc_tty_driver(legacy_count
);
392 panic("Couldn't allocate pty driver");
394 pty_slave_driver
= alloc_tty_driver(legacy_count
);
395 if (!pty_slave_driver
)
396 panic("Couldn't allocate pty slave driver");
398 pty_driver
->owner
= THIS_MODULE
;
399 pty_driver
->driver_name
= "pty_master";
400 pty_driver
->name
= "pty";
401 pty_driver
->major
= PTY_MASTER_MAJOR
;
402 pty_driver
->minor_start
= 0;
403 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
404 pty_driver
->subtype
= PTY_TYPE_MASTER
;
405 pty_driver
->init_termios
= tty_std_termios
;
406 pty_driver
->init_termios
.c_iflag
= 0;
407 pty_driver
->init_termios
.c_oflag
= 0;
408 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
409 pty_driver
->init_termios
.c_lflag
= 0;
410 pty_driver
->init_termios
.c_ispeed
= 38400;
411 pty_driver
->init_termios
.c_ospeed
= 38400;
412 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
413 pty_driver
->other
= pty_slave_driver
;
414 tty_set_operations(pty_driver
, &master_pty_ops_bsd
);
416 pty_slave_driver
->owner
= THIS_MODULE
;
417 pty_slave_driver
->driver_name
= "pty_slave";
418 pty_slave_driver
->name
= "ttyp";
419 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
420 pty_slave_driver
->minor_start
= 0;
421 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
422 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
423 pty_slave_driver
->init_termios
= tty_std_termios
;
424 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
425 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
426 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
427 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
429 pty_slave_driver
->other
= pty_driver
;
430 tty_set_operations(pty_slave_driver
, &slave_pty_ops_bsd
);
432 if (tty_register_driver(pty_driver
))
433 panic("Couldn't register pty driver");
434 if (tty_register_driver(pty_slave_driver
))
435 panic("Couldn't register pty slave driver");
438 static inline void legacy_pty_init(void) { }
442 #ifdef CONFIG_UNIX98_PTYS
444 * sysctl support for setting limits on the number of Unix98 ptys allocated.
445 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
447 int pty_limit
= NR_UNIX98_PTY_DEFAULT
;
448 static int pty_limit_min
;
449 static int pty_limit_max
= NR_UNIX98_PTY_MAX
;
450 static int pty_count
;
452 static struct cdev ptmx_cdev
;
454 static struct ctl_table pty_table
[] = {
457 .maxlen
= sizeof(int),
460 .proc_handler
= proc_dointvec_minmax
,
461 .extra1
= &pty_limit_min
,
462 .extra2
= &pty_limit_max
,
465 .maxlen
= sizeof(int),
468 .proc_handler
= proc_dointvec
,
473 static struct ctl_table pty_kern_table
[] = {
482 static struct ctl_table pty_root_table
[] = {
484 .procname
= "kernel",
486 .child
= pty_kern_table
,
492 static int pty_unix98_ioctl(struct tty_struct
*tty
, struct file
*file
,
493 unsigned int cmd
, unsigned long arg
)
496 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
497 return pty_set_lock(tty
, (int __user
*)arg
);
498 case TIOCGPTN
: /* Get PT Number */
499 return put_user(tty
->index
, (unsigned int __user
*)arg
);
500 case TIOCSIG
: /* Send signal to other side of pty */
501 return pty_signal(tty
, (int) arg
);
508 * ptm_unix98_lookup - find a pty master
509 * @driver: ptm driver
512 * Look up a pty master device. Called under the tty_mutex for now.
513 * This provides our locking.
516 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
517 struct inode
*ptm_inode
, int idx
)
519 struct tty_struct
*tty
= devpts_get_tty(ptm_inode
, idx
);
526 * pts_unix98_lookup - find a pty slave
527 * @driver: pts driver
530 * Look up a pty master device. Called under the tty_mutex for now.
531 * This provides our locking.
534 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
535 struct inode
*pts_inode
, int idx
)
537 struct tty_struct
*tty
= devpts_get_tty(pts_inode
, idx
);
538 /* Master must be open before slave */
540 return ERR_PTR(-EIO
);
544 static void pty_unix98_shutdown(struct tty_struct
*tty
)
546 /* We have our own method as we don't use the tty index */
550 /* We have no need to install and remove our tty objects as devpts does all
553 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
555 struct tty_struct
*o_tty
;
556 int idx
= tty
->index
;
558 o_tty
= alloc_tty_struct();
561 if (!try_module_get(driver
->other
->owner
)) {
562 /* This cannot in fact currently happen */
563 free_tty_struct(o_tty
);
566 initialize_tty_struct(o_tty
, driver
->other
, idx
);
568 tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
569 if (tty
->termios
== NULL
)
571 *tty
->termios
= driver
->init_termios
;
572 tty
->termios_locked
= tty
->termios
+ 1;
574 o_tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
575 if (o_tty
->termios
== NULL
)
577 *o_tty
->termios
= driver
->other
->init_termios
;
578 o_tty
->termios_locked
= o_tty
->termios
+ 1;
580 tty_driver_kref_get(driver
->other
);
581 if (driver
->subtype
== PTY_TYPE_MASTER
)
583 /* Establish the links in both directions */
587 * All structures have been allocated, so now we install them.
588 * Failures after this point use release_tty to clean up, so
589 * there's no need to null out the local pointers.
591 tty_driver_kref_get(driver
);
596 kfree(o_tty
->termios
);
597 module_put(o_tty
->driver
->owner
);
598 free_tty_struct(o_tty
);
603 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
608 static const struct tty_operations ptm_unix98_ops
= {
609 .lookup
= ptm_unix98_lookup
,
610 .install
= pty_unix98_install
,
611 .remove
= pty_unix98_remove
,
615 .write_room
= pty_write_room
,
616 .flush_buffer
= pty_flush_buffer
,
617 .chars_in_buffer
= pty_chars_in_buffer
,
618 .unthrottle
= pty_unthrottle
,
619 .set_termios
= pty_set_termios
,
620 .ioctl
= pty_unix98_ioctl
,
621 .shutdown
= pty_unix98_shutdown
,
625 static const struct tty_operations pty_unix98_ops
= {
626 .lookup
= pts_unix98_lookup
,
627 .install
= pty_unix98_install
,
628 .remove
= pty_unix98_remove
,
632 .write_room
= pty_write_room
,
633 .flush_buffer
= pty_flush_buffer
,
634 .chars_in_buffer
= pty_chars_in_buffer
,
635 .unthrottle
= pty_unthrottle
,
636 .set_termios
= pty_set_termios
,
637 .shutdown
= pty_unix98_shutdown
641 * ptmx_open - open a unix 98 pty master
642 * @inode: inode of device file
643 * @filp: file pointer to tty
645 * Allocate a unix98 pty master device from the ptmx driver.
647 * Locking: tty_mutex protects the init_dev work. tty->count should
649 * allocated_ptys_lock handles the list of free pty numbers
652 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
654 struct tty_struct
*tty
;
658 nonseekable_open(inode
, filp
);
660 /* find a device that is not in use. */
662 index
= devpts_new_index(inode
);
667 mutex_lock(&tty_mutex
);
669 tty
= tty_init_dev(ptm_driver
, index
, 1);
670 mutex_unlock(&tty_mutex
);
673 retval
= PTR_ERR(tty
);
677 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
679 retval
= tty_add_file(tty
, filp
);
683 retval
= devpts_pty_new(inode
, tty
->link
);
687 retval
= ptm_driver
->ops
->open(tty
, filp
);
695 tty_release(inode
, filp
);
698 devpts_kill_index(inode
, index
);
703 static struct file_operations ptmx_fops
;
705 static void __init
unix98_pty_init(void)
707 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
709 panic("Couldn't allocate Unix98 ptm driver");
710 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
712 panic("Couldn't allocate Unix98 pts driver");
714 ptm_driver
->owner
= THIS_MODULE
;
715 ptm_driver
->driver_name
= "pty_master";
716 ptm_driver
->name
= "ptm";
717 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
718 ptm_driver
->minor_start
= 0;
719 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
720 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
721 ptm_driver
->init_termios
= tty_std_termios
;
722 ptm_driver
->init_termios
.c_iflag
= 0;
723 ptm_driver
->init_termios
.c_oflag
= 0;
724 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
725 ptm_driver
->init_termios
.c_lflag
= 0;
726 ptm_driver
->init_termios
.c_ispeed
= 38400;
727 ptm_driver
->init_termios
.c_ospeed
= 38400;
728 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
729 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
730 ptm_driver
->other
= pts_driver
;
731 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
733 pts_driver
->owner
= THIS_MODULE
;
734 pts_driver
->driver_name
= "pty_slave";
735 pts_driver
->name
= "pts";
736 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
737 pts_driver
->minor_start
= 0;
738 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
739 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
740 pts_driver
->init_termios
= tty_std_termios
;
741 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
742 pts_driver
->init_termios
.c_ispeed
= 38400;
743 pts_driver
->init_termios
.c_ospeed
= 38400;
744 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
745 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
746 pts_driver
->other
= ptm_driver
;
747 tty_set_operations(pts_driver
, &pty_unix98_ops
);
749 if (tty_register_driver(ptm_driver
))
750 panic("Couldn't register Unix98 ptm driver");
751 if (tty_register_driver(pts_driver
))
752 panic("Couldn't register Unix98 pts driver");
754 register_sysctl_table(pty_root_table
);
756 /* Now create the /dev/ptmx special device */
757 tty_default_fops(&ptmx_fops
);
758 ptmx_fops
.open
= ptmx_open
;
760 cdev_init(&ptmx_cdev
, &ptmx_fops
);
761 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
762 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
763 panic("Couldn't register /dev/ptmx driver\n");
764 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
768 static inline void unix98_pty_init(void) { }
771 static int __init
pty_init(void)
777 module_init(pty_init
);