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/string.h>
22 #include <linux/major.h>
24 #include <linux/init.h>
25 #include <linux/smp_lock.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>
32 #include <asm/system.h>
34 #ifdef CONFIG_UNIX98_PTYS
35 static struct tty_driver
*ptm_driver
;
36 static struct tty_driver
*pts_driver
;
39 static void pty_close(struct tty_struct
*tty
, struct file
*filp
)
42 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
)
43 WARN_ON(tty
->count
> 1);
48 wake_up_interruptible(&tty
->read_wait
);
49 wake_up_interruptible(&tty
->write_wait
);
53 tty
->link
->packet
= 0;
54 set_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
55 wake_up_interruptible(&tty
->link
->read_wait
);
56 wake_up_interruptible(&tty
->link
->write_wait
);
57 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
) {
58 set_bit(TTY_OTHER_CLOSED
, &tty
->flags
);
59 #ifdef CONFIG_UNIX98_PTYS
60 if (tty
->driver
== ptm_driver
)
61 devpts_pty_kill(tty
->link
);
63 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 static void pty_flush_buffer(struct tty_struct
*tty
)
174 struct tty_struct
*to
= tty
->link
;
179 /* tty_buffer_flush(to); FIXME */
181 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
182 tty
->ctrl_status
|= TIOCPKT_FLUSHWRITE
;
183 wake_up_interruptible(&to
->read_wait
);
184 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
188 static int pty_open(struct tty_struct
*tty
, struct file
*filp
)
190 int retval
= -ENODEV
;
192 if (!tty
|| !tty
->link
)
196 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
198 if (test_bit(TTY_PTY_LOCK
, &tty
->link
->flags
))
200 if (tty
->link
->count
!= 1)
203 clear_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
204 set_bit(TTY_THROTTLED
, &tty
->flags
);
210 static void pty_set_termios(struct tty_struct
*tty
,
211 struct ktermios
*old_termios
)
213 tty
->termios
->c_cflag
&= ~(CSIZE
| PARENB
);
214 tty
->termios
->c_cflag
|= (CS8
| CREAD
);
218 * pty_do_resize - resize event
219 * @tty: tty being resized
220 * @ws: window size being set.
222 * Update the termios variables and send the neccessary signals to
223 * peform a terminal resize correctly
226 int pty_resize(struct tty_struct
*tty
, struct winsize
*ws
)
228 struct pid
*pgrp
, *rpgrp
;
230 struct tty_struct
*pty
= tty
->link
;
232 /* For a PTY we need to lock the tty side */
233 mutex_lock(&tty
->termios_mutex
);
234 if (!memcmp(ws
, &tty
->winsize
, sizeof(*ws
)))
237 /* Get the PID values and reference them so we can
238 avoid holding the tty ctrl lock while sending signals.
239 We need to lock these individually however. */
241 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
242 pgrp
= get_pid(tty
->pgrp
);
243 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
245 spin_lock_irqsave(&pty
->ctrl_lock
, flags
);
246 rpgrp
= get_pid(pty
->pgrp
);
247 spin_unlock_irqrestore(&pty
->ctrl_lock
, flags
);
250 kill_pgrp(pgrp
, SIGWINCH
, 1);
251 if (rpgrp
!= pgrp
&& rpgrp
)
252 kill_pgrp(rpgrp
, SIGWINCH
, 1);
258 pty
->winsize
= *ws
; /* Never used so will go away soon */
260 mutex_unlock(&tty
->termios_mutex
);
264 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
266 struct tty_struct
*o_tty
;
267 int idx
= tty
->index
;
270 o_tty
= alloc_tty_struct();
273 if (!try_module_get(driver
->other
->owner
)) {
274 /* This cannot in fact currently happen */
275 free_tty_struct(o_tty
);
278 initialize_tty_struct(o_tty
, driver
->other
, idx
);
280 /* We always use new tty termios data so we can do this
282 retval
= tty_init_termios(tty
);
286 retval
= tty_init_termios(o_tty
);
288 tty_free_termios(tty
);
293 * Everything allocated ... set up the o_tty structure.
295 driver
->other
->ttys
[idx
] = o_tty
;
296 tty_driver_kref_get(driver
->other
);
297 if (driver
->subtype
== PTY_TYPE_MASTER
)
299 /* Establish the links in both directions */
303 tty_driver_kref_get(driver
);
305 driver
->ttys
[idx
] = tty
;
308 module_put(o_tty
->driver
->owner
);
309 free_tty_struct(o_tty
);
314 static const struct tty_operations pty_ops
= {
315 .install
= pty_install
,
319 .write_room
= pty_write_room
,
320 .flush_buffer
= pty_flush_buffer
,
321 .chars_in_buffer
= pty_chars_in_buffer
,
322 .unthrottle
= pty_unthrottle
,
323 .set_termios
= pty_set_termios
,
327 /* Traditional BSD devices */
328 #ifdef CONFIG_LEGACY_PTYS
329 static struct tty_driver
*pty_driver
, *pty_slave_driver
;
331 static int pty_bsd_ioctl(struct tty_struct
*tty
, struct file
*file
,
332 unsigned int cmd
, unsigned long arg
)
335 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
336 return pty_set_lock(tty
, (int __user
*) arg
);
341 static int legacy_count
= CONFIG_LEGACY_PTY_COUNT
;
342 module_param(legacy_count
, int, 0);
344 static const struct tty_operations pty_ops_bsd
= {
348 .write_room
= pty_write_room
,
349 .flush_buffer
= pty_flush_buffer
,
350 .chars_in_buffer
= pty_chars_in_buffer
,
351 .unthrottle
= pty_unthrottle
,
352 .set_termios
= pty_set_termios
,
353 .ioctl
= pty_bsd_ioctl
,
357 static void __init
legacy_pty_init(void)
359 if (legacy_count
<= 0)
362 pty_driver
= alloc_tty_driver(legacy_count
);
364 panic("Couldn't allocate pty driver");
366 pty_slave_driver
= alloc_tty_driver(legacy_count
);
367 if (!pty_slave_driver
)
368 panic("Couldn't allocate pty slave driver");
370 pty_driver
->owner
= THIS_MODULE
;
371 pty_driver
->driver_name
= "pty_master";
372 pty_driver
->name
= "pty";
373 pty_driver
->major
= PTY_MASTER_MAJOR
;
374 pty_driver
->minor_start
= 0;
375 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
376 pty_driver
->subtype
= PTY_TYPE_MASTER
;
377 pty_driver
->init_termios
= tty_std_termios
;
378 pty_driver
->init_termios
.c_iflag
= 0;
379 pty_driver
->init_termios
.c_oflag
= 0;
380 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
381 pty_driver
->init_termios
.c_lflag
= 0;
382 pty_driver
->init_termios
.c_ispeed
= 38400;
383 pty_driver
->init_termios
.c_ospeed
= 38400;
384 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
385 pty_driver
->other
= pty_slave_driver
;
386 tty_set_operations(pty_driver
, &pty_ops
);
388 pty_slave_driver
->owner
= THIS_MODULE
;
389 pty_slave_driver
->driver_name
= "pty_slave";
390 pty_slave_driver
->name
= "ttyp";
391 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
392 pty_slave_driver
->minor_start
= 0;
393 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
394 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
395 pty_slave_driver
->init_termios
= tty_std_termios
;
396 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
397 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
398 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
399 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
401 pty_slave_driver
->other
= pty_driver
;
402 tty_set_operations(pty_slave_driver
, &pty_ops
);
404 if (tty_register_driver(pty_driver
))
405 panic("Couldn't register pty driver");
406 if (tty_register_driver(pty_slave_driver
))
407 panic("Couldn't register pty slave driver");
410 static inline void legacy_pty_init(void) { }
414 #ifdef CONFIG_UNIX98_PTYS
416 * sysctl support for setting limits on the number of Unix98 ptys allocated.
417 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
419 int pty_limit
= NR_UNIX98_PTY_DEFAULT
;
420 static int pty_limit_min
;
421 static int pty_limit_max
= NR_UNIX98_PTY_MAX
;
422 static int pty_count
;
424 static struct cdev ptmx_cdev
;
426 static struct ctl_table pty_table
[] = {
430 .maxlen
= sizeof(int),
433 .proc_handler
= &proc_dointvec_minmax
,
434 .strategy
= &sysctl_intvec
,
435 .extra1
= &pty_limit_min
,
436 .extra2
= &pty_limit_max
,
440 .maxlen
= sizeof(int),
443 .proc_handler
= &proc_dointvec
,
449 static struct ctl_table pty_kern_table
[] = {
451 .ctl_name
= KERN_PTY
,
459 static struct ctl_table pty_root_table
[] = {
461 .ctl_name
= CTL_KERN
,
462 .procname
= "kernel",
464 .child
= pty_kern_table
,
470 static int pty_unix98_ioctl(struct tty_struct
*tty
, struct file
*file
,
471 unsigned int cmd
, unsigned long arg
)
474 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
475 return pty_set_lock(tty
, (int __user
*)arg
);
476 case TIOCGPTN
: /* Get PT Number */
477 return put_user(tty
->index
, (unsigned int __user
*)arg
);
484 * ptm_unix98_lookup - find a pty master
485 * @driver: ptm driver
488 * Look up a pty master device. Called under the tty_mutex for now.
489 * This provides our locking.
492 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
493 struct inode
*ptm_inode
, int idx
)
495 struct tty_struct
*tty
= devpts_get_tty(ptm_inode
, idx
);
502 * pts_unix98_lookup - find a pty slave
503 * @driver: pts driver
506 * Look up a pty master device. Called under the tty_mutex for now.
507 * This provides our locking.
510 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
511 struct inode
*pts_inode
, int idx
)
513 struct tty_struct
*tty
= devpts_get_tty(pts_inode
, idx
);
514 /* Master must be open before slave */
516 return ERR_PTR(-EIO
);
520 static void pty_unix98_shutdown(struct tty_struct
*tty
)
522 /* We have our own method as we don't use the tty index */
526 /* We have no need to install and remove our tty objects as devpts does all
529 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
531 struct tty_struct
*o_tty
;
532 int idx
= tty
->index
;
534 o_tty
= alloc_tty_struct();
537 if (!try_module_get(driver
->other
->owner
)) {
538 /* This cannot in fact currently happen */
539 free_tty_struct(o_tty
);
542 initialize_tty_struct(o_tty
, driver
->other
, idx
);
544 tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
545 if (tty
->termios
== NULL
)
547 *tty
->termios
= driver
->init_termios
;
548 tty
->termios_locked
= tty
->termios
+ 1;
550 o_tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
551 if (o_tty
->termios
== NULL
)
553 *o_tty
->termios
= driver
->other
->init_termios
;
554 o_tty
->termios_locked
= o_tty
->termios
+ 1;
556 tty_driver_kref_get(driver
->other
);
557 if (driver
->subtype
== PTY_TYPE_MASTER
)
559 /* Establish the links in both directions */
563 * All structures have been allocated, so now we install them.
564 * Failures after this point use release_tty to clean up, so
565 * there's no need to null out the local pointers.
567 tty_driver_kref_get(driver
);
572 kfree(o_tty
->termios
);
573 module_put(o_tty
->driver
->owner
);
574 free_tty_struct(o_tty
);
579 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
584 static const struct tty_operations ptm_unix98_ops
= {
585 .lookup
= ptm_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 .ioctl
= pty_unix98_ioctl
,
597 .shutdown
= pty_unix98_shutdown
,
601 static const struct tty_operations pty_unix98_ops
= {
602 .lookup
= pts_unix98_lookup
,
603 .install
= pty_unix98_install
,
604 .remove
= pty_unix98_remove
,
608 .write_room
= pty_write_room
,
609 .flush_buffer
= pty_flush_buffer
,
610 .chars_in_buffer
= pty_chars_in_buffer
,
611 .unthrottle
= pty_unthrottle
,
612 .set_termios
= pty_set_termios
,
613 .shutdown
= pty_unix98_shutdown
617 * ptmx_open - open a unix 98 pty master
618 * @inode: inode of device file
619 * @filp: file pointer to tty
621 * Allocate a unix98 pty master device from the ptmx driver.
623 * Locking: tty_mutex protects the init_dev work. tty->count should
625 * allocated_ptys_lock handles the list of free pty numbers
628 static int __ptmx_open(struct inode
*inode
, struct file
*filp
)
630 struct tty_struct
*tty
;
634 nonseekable_open(inode
, filp
);
636 /* find a device that is not in use. */
637 index
= devpts_new_index(inode
);
641 mutex_lock(&tty_mutex
);
642 tty
= tty_init_dev(ptm_driver
, index
, 1);
643 mutex_unlock(&tty_mutex
);
646 retval
= PTR_ERR(tty
);
650 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
651 filp
->private_data
= tty
;
652 file_move(filp
, &tty
->tty_files
);
654 retval
= devpts_pty_new(inode
, tty
->link
);
658 retval
= ptm_driver
->ops
->open(tty
, filp
);
662 tty_release_dev(filp
);
665 devpts_kill_index(inode
, index
);
669 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
674 ret
= __ptmx_open(inode
, filp
);
679 static struct file_operations ptmx_fops
;
681 static void __init
unix98_pty_init(void)
683 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
685 panic("Couldn't allocate Unix98 ptm driver");
686 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
688 panic("Couldn't allocate Unix98 pts driver");
690 ptm_driver
->owner
= THIS_MODULE
;
691 ptm_driver
->driver_name
= "pty_master";
692 ptm_driver
->name
= "ptm";
693 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
694 ptm_driver
->minor_start
= 0;
695 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
696 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
697 ptm_driver
->init_termios
= tty_std_termios
;
698 ptm_driver
->init_termios
.c_iflag
= 0;
699 ptm_driver
->init_termios
.c_oflag
= 0;
700 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
701 ptm_driver
->init_termios
.c_lflag
= 0;
702 ptm_driver
->init_termios
.c_ispeed
= 38400;
703 ptm_driver
->init_termios
.c_ospeed
= 38400;
704 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
705 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
706 ptm_driver
->other
= pts_driver
;
707 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
709 pts_driver
->owner
= THIS_MODULE
;
710 pts_driver
->driver_name
= "pty_slave";
711 pts_driver
->name
= "pts";
712 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
713 pts_driver
->minor_start
= 0;
714 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
715 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
716 pts_driver
->init_termios
= tty_std_termios
;
717 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
718 pts_driver
->init_termios
.c_ispeed
= 38400;
719 pts_driver
->init_termios
.c_ospeed
= 38400;
720 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
721 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
722 pts_driver
->other
= ptm_driver
;
723 tty_set_operations(pts_driver
, &pty_unix98_ops
);
725 if (tty_register_driver(ptm_driver
))
726 panic("Couldn't register Unix98 ptm driver");
727 if (tty_register_driver(pts_driver
))
728 panic("Couldn't register Unix98 pts driver");
730 register_sysctl_table(pty_root_table
);
732 /* Now create the /dev/ptmx special device */
733 tty_default_fops(&ptmx_fops
);
734 ptmx_fops
.open
= ptmx_open
;
736 cdev_init(&ptmx_cdev
, &ptmx_fops
);
737 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
738 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
739 panic("Couldn't register /dev/ptmx driver\n");
740 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
744 static inline void unix98_pty_init(void) { }
747 static int __init
pty_init(void)
753 module_init(pty_init
);