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/sysctl.h>
27 #include <linux/device.h>
28 #include <linux/uaccess.h>
29 #include <linux/bitops.h>
30 #include <linux/devpts_fs.h>
31 #include <linux/slab.h>
33 #include <asm/system.h>
35 #ifdef CONFIG_UNIX98_PTYS
36 static struct tty_driver
*ptm_driver
;
37 static struct tty_driver
*pts_driver
;
40 static void pty_close(struct tty_struct
*tty
, struct file
*filp
)
43 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
)
44 WARN_ON(tty
->count
> 1);
49 wake_up_interruptible(&tty
->read_wait
);
50 wake_up_interruptible(&tty
->write_wait
);
54 tty
->link
->packet
= 0;
55 set_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
56 wake_up_interruptible(&tty
->link
->read_wait
);
57 wake_up_interruptible(&tty
->link
->write_wait
);
58 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
) {
59 set_bit(TTY_OTHER_CLOSED
, &tty
->flags
);
60 #ifdef CONFIG_UNIX98_PTYS
61 if (tty
->driver
== ptm_driver
)
62 devpts_pty_kill(tty
->link
);
65 tty_vhangup(tty
->link
);
71 * The unthrottle routine is called by the line discipline to signal
72 * that it can receive more characters. For PTY's, the TTY_THROTTLED
73 * flag is always set, to force the line discipline to always call the
74 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
75 * characters in the queue. This is necessary since each time this
76 * happens, we need to wake up any sleeping processes that could be
77 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
78 * for the pty buffer to be drained.
80 static void pty_unthrottle(struct tty_struct
*tty
)
82 tty_wakeup(tty
->link
);
83 set_bit(TTY_THROTTLED
, &tty
->flags
);
87 * pty_space - report space left for writing
88 * @to: tty we are writing into
90 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
91 * allows a lot of overspill room for echo and other fun messes to
95 static int pty_space(struct tty_struct
*to
)
97 int n
= 8192 - to
->buf
.memory_used
;
104 * pty_write - write to a pty
105 * @tty: the tty we write from
106 * @buf: kernel buffer of data
107 * @count: bytes to write
109 * Our "hardware" write method. Data is coming from the ldisc which
110 * may be in a non sleeping state. We simply throw this at the other
111 * end of the link as if we were an IRQ handler receiving stuff for
112 * the other side of the pty/tty pair.
115 static int pty_write(struct tty_struct
*tty
, const unsigned char *buf
, int c
)
117 struct tty_struct
*to
= tty
->link
;
123 /* Stuff the data into the input queue of the other end */
124 c
= tty_insert_flip_string(to
, buf
, c
);
127 tty_flip_buffer_push(to
);
135 * pty_write_room - write space
136 * @tty: tty we are writing from
138 * Report how many bytes the ldisc can send into the queue for
142 static int pty_write_room(struct tty_struct
*tty
)
146 return pty_space(tty
->link
);
150 * pty_chars_in_buffer - characters currently in our tx queue
153 * Report how much we have in the transmit queue. As everything is
154 * instantly at the other end this is easy to implement.
157 static int pty_chars_in_buffer(struct tty_struct
*tty
)
162 /* Set the lock flag on a pty */
163 static int pty_set_lock(struct tty_struct
*tty
, int __user
*arg
)
166 if (get_user(val
, arg
))
169 set_bit(TTY_PTY_LOCK
, &tty
->flags
);
171 clear_bit(TTY_PTY_LOCK
, &tty
->flags
);
175 /* Send a signal to the slave */
176 static int pty_signal(struct tty_struct
*tty
, int sig
)
182 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
183 pgrp
= get_pid(tty
->link
->pgrp
);
184 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
186 kill_pgrp(pgrp
, sig
, 1);
192 static void pty_flush_buffer(struct tty_struct
*tty
)
194 struct tty_struct
*to
= tty
->link
;
199 /* tty_buffer_flush(to); FIXME */
201 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
202 tty
->ctrl_status
|= TIOCPKT_FLUSHWRITE
;
203 wake_up_interruptible(&to
->read_wait
);
204 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
208 static int pty_open(struct tty_struct
*tty
, struct file
*filp
)
210 int retval
= -ENODEV
;
212 if (!tty
|| !tty
->link
)
216 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
218 if (test_bit(TTY_PTY_LOCK
, &tty
->link
->flags
))
220 if (tty
->link
->count
!= 1)
223 clear_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
224 set_bit(TTY_THROTTLED
, &tty
->flags
);
230 static void pty_set_termios(struct tty_struct
*tty
,
231 struct ktermios
*old_termios
)
233 tty
->termios
->c_cflag
&= ~(CSIZE
| PARENB
);
234 tty
->termios
->c_cflag
|= (CS8
| CREAD
);
238 * pty_do_resize - resize event
239 * @tty: tty being resized
240 * @ws: window size being set.
242 * Update the termios variables and send the necessary signals to
243 * peform a terminal resize correctly
246 int pty_resize(struct tty_struct
*tty
, struct winsize
*ws
)
248 struct pid
*pgrp
, *rpgrp
;
250 struct tty_struct
*pty
= tty
->link
;
252 /* For a PTY we need to lock the tty side */
253 mutex_lock(&tty
->termios_mutex
);
254 if (!memcmp(ws
, &tty
->winsize
, sizeof(*ws
)))
257 /* Get the PID values and reference them so we can
258 avoid holding the tty ctrl lock while sending signals.
259 We need to lock these individually however. */
261 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
262 pgrp
= get_pid(tty
->pgrp
);
263 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
265 spin_lock_irqsave(&pty
->ctrl_lock
, flags
);
266 rpgrp
= get_pid(pty
->pgrp
);
267 spin_unlock_irqrestore(&pty
->ctrl_lock
, flags
);
270 kill_pgrp(pgrp
, SIGWINCH
, 1);
271 if (rpgrp
!= pgrp
&& rpgrp
)
272 kill_pgrp(rpgrp
, SIGWINCH
, 1);
278 pty
->winsize
= *ws
; /* Never used so will go away soon */
280 mutex_unlock(&tty
->termios_mutex
);
284 /* Traditional BSD devices */
285 #ifdef CONFIG_LEGACY_PTYS
287 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
289 struct tty_struct
*o_tty
;
290 int idx
= tty
->index
;
293 o_tty
= alloc_tty_struct();
296 if (!try_module_get(driver
->other
->owner
)) {
297 /* This cannot in fact currently happen */
301 initialize_tty_struct(o_tty
, driver
->other
, idx
);
303 /* We always use new tty termios data so we can do this
305 retval
= tty_init_termios(tty
);
309 retval
= tty_init_termios(o_tty
);
311 goto err_free_termios
;
314 * Everything allocated ... set up the o_tty structure.
316 driver
->other
->ttys
[idx
] = o_tty
;
317 tty_driver_kref_get(driver
->other
);
318 if (driver
->subtype
== PTY_TYPE_MASTER
)
320 /* Establish the links in both directions */
324 tty_driver_kref_get(driver
);
326 driver
->ttys
[idx
] = tty
;
329 tty_free_termios(tty
);
331 deinitialize_tty_struct(o_tty
);
332 module_put(o_tty
->driver
->owner
);
334 free_tty_struct(o_tty
);
338 static int pty_bsd_ioctl(struct tty_struct
*tty
,
339 unsigned int cmd
, unsigned long arg
)
342 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
343 return pty_set_lock(tty
, (int __user
*) arg
);
344 case TIOCSIG
: /* Send signal to other side of pty */
345 return pty_signal(tty
, (int) arg
);
350 static int legacy_count
= CONFIG_LEGACY_PTY_COUNT
;
351 module_param(legacy_count
, int, 0);
354 * The master side of a pty can do TIOCSPTLCK and thus
357 static const struct tty_operations master_pty_ops_bsd
= {
358 .install
= pty_install
,
362 .write_room
= pty_write_room
,
363 .flush_buffer
= pty_flush_buffer
,
364 .chars_in_buffer
= pty_chars_in_buffer
,
365 .unthrottle
= pty_unthrottle
,
366 .set_termios
= pty_set_termios
,
367 .ioctl
= pty_bsd_ioctl
,
371 static const struct tty_operations slave_pty_ops_bsd
= {
372 .install
= pty_install
,
376 .write_room
= pty_write_room
,
377 .flush_buffer
= pty_flush_buffer
,
378 .chars_in_buffer
= pty_chars_in_buffer
,
379 .unthrottle
= pty_unthrottle
,
380 .set_termios
= pty_set_termios
,
384 static void __init
legacy_pty_init(void)
386 struct tty_driver
*pty_driver
, *pty_slave_driver
;
388 if (legacy_count
<= 0)
391 pty_driver
= alloc_tty_driver(legacy_count
);
393 panic("Couldn't allocate pty driver");
395 pty_slave_driver
= alloc_tty_driver(legacy_count
);
396 if (!pty_slave_driver
)
397 panic("Couldn't allocate pty slave driver");
399 pty_driver
->owner
= THIS_MODULE
;
400 pty_driver
->driver_name
= "pty_master";
401 pty_driver
->name
= "pty";
402 pty_driver
->major
= PTY_MASTER_MAJOR
;
403 pty_driver
->minor_start
= 0;
404 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
405 pty_driver
->subtype
= PTY_TYPE_MASTER
;
406 pty_driver
->init_termios
= tty_std_termios
;
407 pty_driver
->init_termios
.c_iflag
= 0;
408 pty_driver
->init_termios
.c_oflag
= 0;
409 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
410 pty_driver
->init_termios
.c_lflag
= 0;
411 pty_driver
->init_termios
.c_ispeed
= 38400;
412 pty_driver
->init_termios
.c_ospeed
= 38400;
413 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
414 pty_driver
->other
= pty_slave_driver
;
415 tty_set_operations(pty_driver
, &master_pty_ops_bsd
);
417 pty_slave_driver
->owner
= THIS_MODULE
;
418 pty_slave_driver
->driver_name
= "pty_slave";
419 pty_slave_driver
->name
= "ttyp";
420 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
421 pty_slave_driver
->minor_start
= 0;
422 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
423 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
424 pty_slave_driver
->init_termios
= tty_std_termios
;
425 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
426 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
427 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
428 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
430 pty_slave_driver
->other
= pty_driver
;
431 tty_set_operations(pty_slave_driver
, &slave_pty_ops_bsd
);
433 if (tty_register_driver(pty_driver
))
434 panic("Couldn't register pty driver");
435 if (tty_register_driver(pty_slave_driver
))
436 panic("Couldn't register pty slave driver");
439 static inline void legacy_pty_init(void) { }
443 #ifdef CONFIG_UNIX98_PTYS
445 * sysctl support for setting limits on the number of Unix98 ptys allocated.
446 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
448 int pty_limit
= NR_UNIX98_PTY_DEFAULT
;
449 static int pty_limit_min
;
450 static int pty_limit_max
= NR_UNIX98_PTY_MAX
;
451 static int pty_count
;
453 static struct cdev ptmx_cdev
;
455 static struct ctl_table pty_table
[] = {
458 .maxlen
= sizeof(int),
461 .proc_handler
= proc_dointvec_minmax
,
462 .extra1
= &pty_limit_min
,
463 .extra2
= &pty_limit_max
,
466 .maxlen
= sizeof(int),
469 .proc_handler
= proc_dointvec
,
474 static struct ctl_table pty_kern_table
[] = {
483 static struct ctl_table pty_root_table
[] = {
485 .procname
= "kernel",
487 .child
= pty_kern_table
,
493 static int pty_unix98_ioctl(struct tty_struct
*tty
,
494 unsigned int cmd
, unsigned long arg
)
497 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
498 return pty_set_lock(tty
, (int __user
*)arg
);
499 case TIOCGPTN
: /* Get PT Number */
500 return put_user(tty
->index
, (unsigned int __user
*)arg
);
501 case TIOCSIG
: /* Send signal to other side of pty */
502 return pty_signal(tty
, (int) arg
);
509 * ptm_unix98_lookup - find a pty master
510 * @driver: ptm driver
513 * Look up a pty master device. Called under the tty_mutex for now.
514 * This provides our locking.
517 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
518 struct inode
*ptm_inode
, int idx
)
520 struct tty_struct
*tty
= devpts_get_tty(ptm_inode
, idx
);
527 * pts_unix98_lookup - find a pty slave
528 * @driver: pts driver
531 * Look up a pty master device. Called under the tty_mutex for now.
532 * This provides our locking.
535 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
536 struct inode
*pts_inode
, int idx
)
538 struct tty_struct
*tty
= devpts_get_tty(pts_inode
, idx
);
539 /* Master must be open before slave */
541 return ERR_PTR(-EIO
);
545 static void pty_unix98_shutdown(struct tty_struct
*tty
)
547 /* We have our own method as we don't use the tty index */
551 /* We have no need to install and remove our tty objects as devpts does all
554 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
556 struct tty_struct
*o_tty
;
557 int idx
= tty
->index
;
559 o_tty
= alloc_tty_struct();
562 if (!try_module_get(driver
->other
->owner
)) {
563 /* This cannot in fact currently happen */
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 deinitialize_tty_struct(o_tty
);
597 kfree(o_tty
->termios
);
599 module_put(o_tty
->driver
->owner
);
601 free_tty_struct(o_tty
);
605 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
610 static const struct tty_operations ptm_unix98_ops
= {
611 .lookup
= ptm_unix98_lookup
,
612 .install
= pty_unix98_install
,
613 .remove
= pty_unix98_remove
,
617 .write_room
= pty_write_room
,
618 .flush_buffer
= pty_flush_buffer
,
619 .chars_in_buffer
= pty_chars_in_buffer
,
620 .unthrottle
= pty_unthrottle
,
621 .set_termios
= pty_set_termios
,
622 .ioctl
= pty_unix98_ioctl
,
623 .shutdown
= pty_unix98_shutdown
,
627 static const struct tty_operations pty_unix98_ops
= {
628 .lookup
= pts_unix98_lookup
,
629 .install
= pty_unix98_install
,
630 .remove
= pty_unix98_remove
,
634 .write_room
= pty_write_room
,
635 .flush_buffer
= pty_flush_buffer
,
636 .chars_in_buffer
= pty_chars_in_buffer
,
637 .unthrottle
= pty_unthrottle
,
638 .set_termios
= pty_set_termios
,
639 .shutdown
= pty_unix98_shutdown
643 * ptmx_open - open a unix 98 pty master
644 * @inode: inode of device file
645 * @filp: file pointer to tty
647 * Allocate a unix98 pty master device from the ptmx driver.
649 * Locking: tty_mutex protects the init_dev work. tty->count should
651 * allocated_ptys_lock handles the list of free pty numbers
654 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
656 struct tty_struct
*tty
;
660 nonseekable_open(inode
, filp
);
662 /* find a device that is not in use. */
664 index
= devpts_new_index(inode
);
669 mutex_lock(&tty_mutex
);
671 tty
= tty_init_dev(ptm_driver
, index
, 1);
672 mutex_unlock(&tty_mutex
);
675 retval
= PTR_ERR(tty
);
679 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
681 retval
= tty_add_file(tty
, filp
);
685 retval
= devpts_pty_new(inode
, tty
->link
);
689 retval
= ptm_driver
->ops
->open(tty
, filp
);
697 tty_release(inode
, filp
);
700 devpts_kill_index(inode
, index
);
705 static struct file_operations ptmx_fops
;
707 static void __init
unix98_pty_init(void)
709 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
711 panic("Couldn't allocate Unix98 ptm driver");
712 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
714 panic("Couldn't allocate Unix98 pts driver");
716 ptm_driver
->owner
= THIS_MODULE
;
717 ptm_driver
->driver_name
= "pty_master";
718 ptm_driver
->name
= "ptm";
719 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
720 ptm_driver
->minor_start
= 0;
721 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
722 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
723 ptm_driver
->init_termios
= tty_std_termios
;
724 ptm_driver
->init_termios
.c_iflag
= 0;
725 ptm_driver
->init_termios
.c_oflag
= 0;
726 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
727 ptm_driver
->init_termios
.c_lflag
= 0;
728 ptm_driver
->init_termios
.c_ispeed
= 38400;
729 ptm_driver
->init_termios
.c_ospeed
= 38400;
730 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
731 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
732 ptm_driver
->other
= pts_driver
;
733 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
735 pts_driver
->owner
= THIS_MODULE
;
736 pts_driver
->driver_name
= "pty_slave";
737 pts_driver
->name
= "pts";
738 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
739 pts_driver
->minor_start
= 0;
740 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
741 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
742 pts_driver
->init_termios
= tty_std_termios
;
743 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
744 pts_driver
->init_termios
.c_ispeed
= 38400;
745 pts_driver
->init_termios
.c_ospeed
= 38400;
746 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
747 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
748 pts_driver
->other
= ptm_driver
;
749 tty_set_operations(pts_driver
, &pty_unix98_ops
);
751 if (tty_register_driver(ptm_driver
))
752 panic("Couldn't register Unix98 ptm driver");
753 if (tty_register_driver(pts_driver
))
754 panic("Couldn't register Unix98 pts driver");
756 register_sysctl_table(pty_root_table
);
758 /* Now create the /dev/ptmx special device */
759 tty_default_fops(&ptmx_fops
);
760 ptmx_fops
.open
= ptmx_open
;
762 cdev_init(&ptmx_cdev
, &ptmx_fops
);
763 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
764 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
765 panic("Couldn't register /dev/ptmx driver\n");
766 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
770 static inline void unix98_pty_init(void) { }
773 static int __init
pty_init(void)
779 module_init(pty_init
);