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
);
65 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
);
283 /* Traditional BSD devices */
284 #ifdef CONFIG_LEGACY_PTYS
286 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
288 struct tty_struct
*o_tty
;
289 int idx
= tty
->index
;
292 o_tty
= alloc_tty_struct();
295 if (!try_module_get(driver
->other
->owner
)) {
296 /* This cannot in fact currently happen */
297 free_tty_struct(o_tty
);
300 initialize_tty_struct(o_tty
, driver
->other
, idx
);
302 /* We always use new tty termios data so we can do this
304 retval
= tty_init_termios(tty
);
308 retval
= tty_init_termios(o_tty
);
310 tty_free_termios(tty
);
315 * Everything allocated ... set up the o_tty structure.
317 driver
->other
->ttys
[idx
] = o_tty
;
318 tty_driver_kref_get(driver
->other
);
319 if (driver
->subtype
== PTY_TYPE_MASTER
)
321 /* Establish the links in both directions */
325 tty_driver_kref_get(driver
);
327 driver
->ttys
[idx
] = tty
;
330 module_put(o_tty
->driver
->owner
);
331 free_tty_struct(o_tty
);
335 static int pty_bsd_ioctl(struct tty_struct
*tty
, struct file
*file
,
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
->owner
= THIS_MODULE
;
397 pty_driver
->driver_name
= "pty_master";
398 pty_driver
->name
= "pty";
399 pty_driver
->major
= PTY_MASTER_MAJOR
;
400 pty_driver
->minor_start
= 0;
401 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
402 pty_driver
->subtype
= PTY_TYPE_MASTER
;
403 pty_driver
->init_termios
= tty_std_termios
;
404 pty_driver
->init_termios
.c_iflag
= 0;
405 pty_driver
->init_termios
.c_oflag
= 0;
406 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
407 pty_driver
->init_termios
.c_lflag
= 0;
408 pty_driver
->init_termios
.c_ispeed
= 38400;
409 pty_driver
->init_termios
.c_ospeed
= 38400;
410 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
411 pty_driver
->other
= pty_slave_driver
;
412 tty_set_operations(pty_driver
, &master_pty_ops_bsd
);
414 pty_slave_driver
->owner
= THIS_MODULE
;
415 pty_slave_driver
->driver_name
= "pty_slave";
416 pty_slave_driver
->name
= "ttyp";
417 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
418 pty_slave_driver
->minor_start
= 0;
419 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
420 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
421 pty_slave_driver
->init_termios
= tty_std_termios
;
422 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
423 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
424 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
425 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
427 pty_slave_driver
->other
= pty_driver
;
428 tty_set_operations(pty_slave_driver
, &slave_pty_ops_bsd
);
430 if (tty_register_driver(pty_driver
))
431 panic("Couldn't register pty driver");
432 if (tty_register_driver(pty_slave_driver
))
433 panic("Couldn't register pty slave driver");
436 static inline void legacy_pty_init(void) { }
440 #ifdef CONFIG_UNIX98_PTYS
442 * sysctl support for setting limits on the number of Unix98 ptys allocated.
443 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
445 int pty_limit
= NR_UNIX98_PTY_DEFAULT
;
446 static int pty_limit_min
;
447 static int pty_limit_max
= NR_UNIX98_PTY_MAX
;
448 static int pty_count
;
450 static struct cdev ptmx_cdev
;
452 static struct ctl_table pty_table
[] = {
455 .maxlen
= sizeof(int),
458 .proc_handler
= proc_dointvec_minmax
,
459 .extra1
= &pty_limit_min
,
460 .extra2
= &pty_limit_max
,
463 .maxlen
= sizeof(int),
466 .proc_handler
= proc_dointvec
,
471 static struct ctl_table pty_kern_table
[] = {
480 static struct ctl_table pty_root_table
[] = {
482 .procname
= "kernel",
484 .child
= pty_kern_table
,
490 static int pty_unix98_ioctl(struct tty_struct
*tty
, struct file
*file
,
491 unsigned int cmd
, unsigned long arg
)
494 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
495 return pty_set_lock(tty
, (int __user
*)arg
);
496 case TIOCGPTN
: /* Get PT Number */
497 return put_user(tty
->index
, (unsigned int __user
*)arg
);
498 case TIOCSIG
: /* Send signal to other side of pty */
499 return pty_signal(tty
, (int) arg
);
506 * ptm_unix98_lookup - find a pty master
507 * @driver: ptm driver
510 * Look up a pty master device. Called under the tty_mutex for now.
511 * This provides our locking.
514 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
515 struct inode
*ptm_inode
, int idx
)
517 struct tty_struct
*tty
= devpts_get_tty(ptm_inode
, idx
);
524 * pts_unix98_lookup - find a pty slave
525 * @driver: pts driver
528 * Look up a pty master device. Called under the tty_mutex for now.
529 * This provides our locking.
532 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
533 struct inode
*pts_inode
, int idx
)
535 struct tty_struct
*tty
= devpts_get_tty(pts_inode
, idx
);
536 /* Master must be open before slave */
538 return ERR_PTR(-EIO
);
542 static void pty_unix98_shutdown(struct tty_struct
*tty
)
544 /* We have our own method as we don't use the tty index */
548 /* We have no need to install and remove our tty objects as devpts does all
551 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
553 struct tty_struct
*o_tty
;
554 int idx
= tty
->index
;
556 o_tty
= alloc_tty_struct();
559 if (!try_module_get(driver
->other
->owner
)) {
560 /* This cannot in fact currently happen */
561 free_tty_struct(o_tty
);
564 initialize_tty_struct(o_tty
, driver
->other
, idx
);
566 tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
567 if (tty
->termios
== NULL
)
569 *tty
->termios
= driver
->init_termios
;
570 tty
->termios_locked
= tty
->termios
+ 1;
572 o_tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
573 if (o_tty
->termios
== NULL
)
575 *o_tty
->termios
= driver
->other
->init_termios
;
576 o_tty
->termios_locked
= o_tty
->termios
+ 1;
578 tty_driver_kref_get(driver
->other
);
579 if (driver
->subtype
== PTY_TYPE_MASTER
)
581 /* Establish the links in both directions */
585 * All structures have been allocated, so now we install them.
586 * Failures after this point use release_tty to clean up, so
587 * there's no need to null out the local pointers.
589 tty_driver_kref_get(driver
);
594 kfree(o_tty
->termios
);
595 module_put(o_tty
->driver
->owner
);
596 free_tty_struct(o_tty
);
601 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
606 static const struct tty_operations ptm_unix98_ops
= {
607 .lookup
= ptm_unix98_lookup
,
608 .install
= pty_unix98_install
,
609 .remove
= pty_unix98_remove
,
613 .write_room
= pty_write_room
,
614 .flush_buffer
= pty_flush_buffer
,
615 .chars_in_buffer
= pty_chars_in_buffer
,
616 .unthrottle
= pty_unthrottle
,
617 .set_termios
= pty_set_termios
,
618 .ioctl
= pty_unix98_ioctl
,
619 .shutdown
= pty_unix98_shutdown
,
623 static const struct tty_operations pty_unix98_ops
= {
624 .lookup
= pts_unix98_lookup
,
625 .install
= pty_unix98_install
,
626 .remove
= pty_unix98_remove
,
630 .write_room
= pty_write_room
,
631 .flush_buffer
= pty_flush_buffer
,
632 .chars_in_buffer
= pty_chars_in_buffer
,
633 .unthrottle
= pty_unthrottle
,
634 .set_termios
= pty_set_termios
,
635 .shutdown
= pty_unix98_shutdown
639 * ptmx_open - open a unix 98 pty master
640 * @inode: inode of device file
641 * @filp: file pointer to tty
643 * Allocate a unix98 pty master device from the ptmx driver.
645 * Locking: tty_mutex protects the init_dev work. tty->count should
647 * allocated_ptys_lock handles the list of free pty numbers
650 static int __ptmx_open(struct inode
*inode
, struct file
*filp
)
652 struct tty_struct
*tty
;
656 nonseekable_open(inode
, filp
);
658 /* find a device that is not in use. */
659 index
= devpts_new_index(inode
);
663 mutex_lock(&tty_mutex
);
664 tty
= tty_init_dev(ptm_driver
, index
, 1);
665 mutex_unlock(&tty_mutex
);
668 retval
= PTR_ERR(tty
);
672 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
673 filp
->private_data
= tty
;
674 file_move(filp
, &tty
->tty_files
);
676 retval
= devpts_pty_new(inode
, tty
->link
);
680 retval
= ptm_driver
->ops
->open(tty
, filp
);
684 tty_release(inode
, filp
);
687 devpts_kill_index(inode
, index
);
691 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
696 ret
= __ptmx_open(inode
, filp
);
701 static struct file_operations ptmx_fops
;
703 static void __init
unix98_pty_init(void)
705 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
707 panic("Couldn't allocate Unix98 ptm driver");
708 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
710 panic("Couldn't allocate Unix98 pts driver");
712 ptm_driver
->owner
= THIS_MODULE
;
713 ptm_driver
->driver_name
= "pty_master";
714 ptm_driver
->name
= "ptm";
715 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
716 ptm_driver
->minor_start
= 0;
717 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
718 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
719 ptm_driver
->init_termios
= tty_std_termios
;
720 ptm_driver
->init_termios
.c_iflag
= 0;
721 ptm_driver
->init_termios
.c_oflag
= 0;
722 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
723 ptm_driver
->init_termios
.c_lflag
= 0;
724 ptm_driver
->init_termios
.c_ispeed
= 38400;
725 ptm_driver
->init_termios
.c_ospeed
= 38400;
726 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
727 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
728 ptm_driver
->other
= pts_driver
;
729 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
731 pts_driver
->owner
= THIS_MODULE
;
732 pts_driver
->driver_name
= "pty_slave";
733 pts_driver
->name
= "pts";
734 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
735 pts_driver
->minor_start
= 0;
736 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
737 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
738 pts_driver
->init_termios
= tty_std_termios
;
739 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
740 pts_driver
->init_termios
.c_ispeed
= 38400;
741 pts_driver
->init_termios
.c_ospeed
= 38400;
742 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
743 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
744 pts_driver
->other
= ptm_driver
;
745 tty_set_operations(pts_driver
, &pty_unix98_ops
);
747 if (tty_register_driver(ptm_driver
))
748 panic("Couldn't register Unix98 ptm driver");
749 if (tty_register_driver(pts_driver
))
750 panic("Couldn't register Unix98 pts driver");
752 register_sysctl_table(pty_root_table
);
754 /* Now create the /dev/ptmx special device */
755 tty_default_fops(&ptmx_fops
);
756 ptmx_fops
.open
= ptmx_open
;
758 cdev_init(&ptmx_cdev
, &ptmx_fops
);
759 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
760 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
761 panic("Couldn't register /dev/ptmx driver\n");
762 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
766 static inline void unix98_pty_init(void) { }
769 static int __init
pty_init(void)
775 module_init(pty_init
);