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
);
123 tty_flip_buffer_push(to
);
130 * pty_write_room - write space
131 * @tty: tty we are writing from
133 * Report how many bytes the ldisc can send into the queue for
137 static int pty_write_room(struct tty_struct
*tty
)
141 return pty_space(tty
->link
);
145 * pty_chars_in_buffer - characters currently in our tx queue
148 * Report how much we have in the transmit queue. As everything is
149 * instantly at the other end this is easy to implement.
152 static int pty_chars_in_buffer(struct tty_struct
*tty
)
157 /* Set the lock flag on a pty */
158 static int pty_set_lock(struct tty_struct
*tty
, int __user
*arg
)
161 if (get_user(val
, arg
))
164 set_bit(TTY_PTY_LOCK
, &tty
->flags
);
166 clear_bit(TTY_PTY_LOCK
, &tty
->flags
);
170 static void pty_flush_buffer(struct tty_struct
*tty
)
172 struct tty_struct
*to
= tty
->link
;
177 /* tty_buffer_flush(to); FIXME */
179 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
180 tty
->ctrl_status
|= TIOCPKT_FLUSHWRITE
;
181 wake_up_interruptible(&to
->read_wait
);
182 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
186 static int pty_open(struct tty_struct
*tty
, struct file
*filp
)
188 int retval
= -ENODEV
;
190 if (!tty
|| !tty
->link
)
194 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
196 if (test_bit(TTY_PTY_LOCK
, &tty
->link
->flags
))
198 if (tty
->link
->count
!= 1)
201 clear_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
202 set_bit(TTY_THROTTLED
, &tty
->flags
);
208 static void pty_set_termios(struct tty_struct
*tty
,
209 struct ktermios
*old_termios
)
211 tty
->termios
->c_cflag
&= ~(CSIZE
| PARENB
);
212 tty
->termios
->c_cflag
|= (CS8
| CREAD
);
216 * pty_do_resize - resize event
217 * @tty: tty being resized
218 * @ws: window size being set.
220 * Update the termios variables and send the neccessary signals to
221 * peform a terminal resize correctly
224 int pty_resize(struct tty_struct
*tty
, struct winsize
*ws
)
226 struct pid
*pgrp
, *rpgrp
;
228 struct tty_struct
*pty
= tty
->link
;
230 /* For a PTY we need to lock the tty side */
231 mutex_lock(&tty
->termios_mutex
);
232 if (!memcmp(ws
, &tty
->winsize
, sizeof(*ws
)))
235 /* Get the PID values and reference them so we can
236 avoid holding the tty ctrl lock while sending signals.
237 We need to lock these individually however. */
239 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
240 pgrp
= get_pid(tty
->pgrp
);
241 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
243 spin_lock_irqsave(&pty
->ctrl_lock
, flags
);
244 rpgrp
= get_pid(pty
->pgrp
);
245 spin_unlock_irqrestore(&pty
->ctrl_lock
, flags
);
248 kill_pgrp(pgrp
, SIGWINCH
, 1);
249 if (rpgrp
!= pgrp
&& rpgrp
)
250 kill_pgrp(rpgrp
, SIGWINCH
, 1);
256 pty
->winsize
= *ws
; /* Never used so will go away soon */
258 mutex_unlock(&tty
->termios_mutex
);
262 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
264 struct tty_struct
*o_tty
;
265 int idx
= tty
->index
;
268 o_tty
= alloc_tty_struct();
271 if (!try_module_get(driver
->other
->owner
)) {
272 /* This cannot in fact currently happen */
273 free_tty_struct(o_tty
);
276 initialize_tty_struct(o_tty
, driver
->other
, idx
);
278 /* We always use new tty termios data so we can do this
280 retval
= tty_init_termios(tty
);
284 retval
= tty_init_termios(o_tty
);
286 tty_free_termios(tty
);
291 * Everything allocated ... set up the o_tty structure.
293 driver
->other
->ttys
[idx
] = o_tty
;
294 tty_driver_kref_get(driver
->other
);
295 if (driver
->subtype
== PTY_TYPE_MASTER
)
297 /* Establish the links in both directions */
301 tty_driver_kref_get(driver
);
303 driver
->ttys
[idx
] = tty
;
306 module_put(o_tty
->driver
->owner
);
307 free_tty_struct(o_tty
);
312 static const struct tty_operations pty_ops
= {
313 .install
= pty_install
,
317 .write_room
= pty_write_room
,
318 .flush_buffer
= pty_flush_buffer
,
319 .chars_in_buffer
= pty_chars_in_buffer
,
320 .unthrottle
= pty_unthrottle
,
321 .set_termios
= pty_set_termios
,
325 /* Traditional BSD devices */
326 #ifdef CONFIG_LEGACY_PTYS
327 static struct tty_driver
*pty_driver
, *pty_slave_driver
;
329 static int pty_bsd_ioctl(struct tty_struct
*tty
, struct file
*file
,
330 unsigned int cmd
, unsigned long arg
)
333 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
334 return pty_set_lock(tty
, (int __user
*) arg
);
339 static int legacy_count
= CONFIG_LEGACY_PTY_COUNT
;
340 module_param(legacy_count
, int, 0);
342 static const struct tty_operations pty_ops_bsd
= {
346 .write_room
= pty_write_room
,
347 .flush_buffer
= pty_flush_buffer
,
348 .chars_in_buffer
= pty_chars_in_buffer
,
349 .unthrottle
= pty_unthrottle
,
350 .set_termios
= pty_set_termios
,
351 .ioctl
= pty_bsd_ioctl
,
355 static void __init
legacy_pty_init(void)
357 if (legacy_count
<= 0)
360 pty_driver
= alloc_tty_driver(legacy_count
);
362 panic("Couldn't allocate pty driver");
364 pty_slave_driver
= alloc_tty_driver(legacy_count
);
365 if (!pty_slave_driver
)
366 panic("Couldn't allocate pty slave driver");
368 pty_driver
->owner
= THIS_MODULE
;
369 pty_driver
->driver_name
= "pty_master";
370 pty_driver
->name
= "pty";
371 pty_driver
->major
= PTY_MASTER_MAJOR
;
372 pty_driver
->minor_start
= 0;
373 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
374 pty_driver
->subtype
= PTY_TYPE_MASTER
;
375 pty_driver
->init_termios
= tty_std_termios
;
376 pty_driver
->init_termios
.c_iflag
= 0;
377 pty_driver
->init_termios
.c_oflag
= 0;
378 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
379 pty_driver
->init_termios
.c_lflag
= 0;
380 pty_driver
->init_termios
.c_ispeed
= 38400;
381 pty_driver
->init_termios
.c_ospeed
= 38400;
382 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
383 pty_driver
->other
= pty_slave_driver
;
384 tty_set_operations(pty_driver
, &pty_ops
);
386 pty_slave_driver
->owner
= THIS_MODULE
;
387 pty_slave_driver
->driver_name
= "pty_slave";
388 pty_slave_driver
->name
= "ttyp";
389 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
390 pty_slave_driver
->minor_start
= 0;
391 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
392 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
393 pty_slave_driver
->init_termios
= tty_std_termios
;
394 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
395 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
396 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
397 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
399 pty_slave_driver
->other
= pty_driver
;
400 tty_set_operations(pty_slave_driver
, &pty_ops
);
402 if (tty_register_driver(pty_driver
))
403 panic("Couldn't register pty driver");
404 if (tty_register_driver(pty_slave_driver
))
405 panic("Couldn't register pty slave driver");
408 static inline void legacy_pty_init(void) { }
412 #ifdef CONFIG_UNIX98_PTYS
414 * sysctl support for setting limits on the number of Unix98 ptys allocated.
415 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
417 int pty_limit
= NR_UNIX98_PTY_DEFAULT
;
418 static int pty_limit_min
;
419 static int pty_limit_max
= NR_UNIX98_PTY_MAX
;
420 static int pty_count
;
422 static struct cdev ptmx_cdev
;
424 static struct ctl_table pty_table
[] = {
428 .maxlen
= sizeof(int),
431 .proc_handler
= &proc_dointvec_minmax
,
432 .strategy
= &sysctl_intvec
,
433 .extra1
= &pty_limit_min
,
434 .extra2
= &pty_limit_max
,
438 .maxlen
= sizeof(int),
441 .proc_handler
= &proc_dointvec
,
447 static struct ctl_table pty_kern_table
[] = {
449 .ctl_name
= KERN_PTY
,
457 static struct ctl_table pty_root_table
[] = {
459 .ctl_name
= CTL_KERN
,
460 .procname
= "kernel",
462 .child
= pty_kern_table
,
468 static int pty_unix98_ioctl(struct tty_struct
*tty
, struct file
*file
,
469 unsigned int cmd
, unsigned long arg
)
472 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
473 return pty_set_lock(tty
, (int __user
*)arg
);
474 case TIOCGPTN
: /* Get PT Number */
475 return put_user(tty
->index
, (unsigned int __user
*)arg
);
482 * ptm_unix98_lookup - find a pty master
483 * @driver: ptm driver
486 * Look up a pty master device. Called under the tty_mutex for now.
487 * This provides our locking.
490 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
491 struct inode
*ptm_inode
, int idx
)
493 struct tty_struct
*tty
= devpts_get_tty(ptm_inode
, idx
);
500 * pts_unix98_lookup - find a pty slave
501 * @driver: pts driver
504 * Look up a pty master device. Called under the tty_mutex for now.
505 * This provides our locking.
508 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
509 struct inode
*pts_inode
, int idx
)
511 struct tty_struct
*tty
= devpts_get_tty(pts_inode
, idx
);
512 /* Master must be open before slave */
514 return ERR_PTR(-EIO
);
518 static void pty_unix98_shutdown(struct tty_struct
*tty
)
520 /* We have our own method as we don't use the tty index */
524 /* We have no need to install and remove our tty objects as devpts does all
527 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
529 struct tty_struct
*o_tty
;
530 int idx
= tty
->index
;
532 o_tty
= alloc_tty_struct();
535 if (!try_module_get(driver
->other
->owner
)) {
536 /* This cannot in fact currently happen */
537 free_tty_struct(o_tty
);
540 initialize_tty_struct(o_tty
, driver
->other
, idx
);
542 tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
543 if (tty
->termios
== NULL
)
545 *tty
->termios
= driver
->init_termios
;
546 tty
->termios_locked
= tty
->termios
+ 1;
548 o_tty
->termios
= kzalloc(sizeof(struct ktermios
[2]), GFP_KERNEL
);
549 if (o_tty
->termios
== NULL
)
551 *o_tty
->termios
= driver
->other
->init_termios
;
552 o_tty
->termios_locked
= o_tty
->termios
+ 1;
554 tty_driver_kref_get(driver
->other
);
555 if (driver
->subtype
== PTY_TYPE_MASTER
)
557 /* Establish the links in both directions */
561 * All structures have been allocated, so now we install them.
562 * Failures after this point use release_tty to clean up, so
563 * there's no need to null out the local pointers.
565 tty_driver_kref_get(driver
);
570 kfree(o_tty
->termios
);
571 module_put(o_tty
->driver
->owner
);
572 free_tty_struct(o_tty
);
577 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
582 static const struct tty_operations ptm_unix98_ops
= {
583 .lookup
= ptm_unix98_lookup
,
584 .install
= pty_unix98_install
,
585 .remove
= pty_unix98_remove
,
589 .write_room
= pty_write_room
,
590 .flush_buffer
= pty_flush_buffer
,
591 .chars_in_buffer
= pty_chars_in_buffer
,
592 .unthrottle
= pty_unthrottle
,
593 .set_termios
= pty_set_termios
,
594 .ioctl
= pty_unix98_ioctl
,
595 .shutdown
= pty_unix98_shutdown
,
599 static const struct tty_operations pty_unix98_ops
= {
600 .lookup
= pts_unix98_lookup
,
601 .install
= pty_unix98_install
,
602 .remove
= pty_unix98_remove
,
606 .write_room
= pty_write_room
,
607 .flush_buffer
= pty_flush_buffer
,
608 .chars_in_buffer
= pty_chars_in_buffer
,
609 .unthrottle
= pty_unthrottle
,
610 .set_termios
= pty_set_termios
,
611 .shutdown
= pty_unix98_shutdown
615 * ptmx_open - open a unix 98 pty master
616 * @inode: inode of device file
617 * @filp: file pointer to tty
619 * Allocate a unix98 pty master device from the ptmx driver.
621 * Locking: tty_mutex protects the init_dev work. tty->count should
623 * allocated_ptys_lock handles the list of free pty numbers
626 static int __ptmx_open(struct inode
*inode
, struct file
*filp
)
628 struct tty_struct
*tty
;
632 nonseekable_open(inode
, filp
);
634 /* find a device that is not in use. */
635 index
= devpts_new_index(inode
);
639 mutex_lock(&tty_mutex
);
640 tty
= tty_init_dev(ptm_driver
, index
, 1);
641 mutex_unlock(&tty_mutex
);
644 retval
= PTR_ERR(tty
);
648 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
649 filp
->private_data
= tty
;
650 file_move(filp
, &tty
->tty_files
);
652 retval
= devpts_pty_new(inode
, tty
->link
);
656 retval
= ptm_driver
->ops
->open(tty
, filp
);
660 tty_release_dev(filp
);
663 devpts_kill_index(inode
, index
);
667 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
672 ret
= __ptmx_open(inode
, filp
);
677 static struct file_operations ptmx_fops
;
679 static void __init
unix98_pty_init(void)
681 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
683 panic("Couldn't allocate Unix98 ptm driver");
684 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
686 panic("Couldn't allocate Unix98 pts driver");
688 ptm_driver
->owner
= THIS_MODULE
;
689 ptm_driver
->driver_name
= "pty_master";
690 ptm_driver
->name
= "ptm";
691 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
692 ptm_driver
->minor_start
= 0;
693 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
694 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
695 ptm_driver
->init_termios
= tty_std_termios
;
696 ptm_driver
->init_termios
.c_iflag
= 0;
697 ptm_driver
->init_termios
.c_oflag
= 0;
698 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
699 ptm_driver
->init_termios
.c_lflag
= 0;
700 ptm_driver
->init_termios
.c_ispeed
= 38400;
701 ptm_driver
->init_termios
.c_ospeed
= 38400;
702 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
703 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
704 ptm_driver
->other
= pts_driver
;
705 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
707 pts_driver
->owner
= THIS_MODULE
;
708 pts_driver
->driver_name
= "pty_slave";
709 pts_driver
->name
= "pts";
710 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
711 pts_driver
->minor_start
= 0;
712 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
713 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
714 pts_driver
->init_termios
= tty_std_termios
;
715 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
716 pts_driver
->init_termios
.c_ispeed
= 38400;
717 pts_driver
->init_termios
.c_ospeed
= 38400;
718 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
719 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
720 pts_driver
->other
= ptm_driver
;
721 tty_set_operations(pts_driver
, &pty_unix98_ops
);
723 if (tty_register_driver(ptm_driver
))
724 panic("Couldn't register Unix98 ptm driver");
725 if (tty_register_driver(pts_driver
))
726 panic("Couldn't register Unix98 pts driver");
728 register_sysctl_table(pty_root_table
);
730 /* Now create the /dev/ptmx special device */
731 tty_default_fops(&ptmx_fops
);
732 ptmx_fops
.open
= ptmx_open
;
734 cdev_init(&ptmx_cdev
, &ptmx_fops
);
735 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
736 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
737 panic("Couldn't register /dev/ptmx driver\n");
738 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
742 static inline void unix98_pty_init(void) { }
745 static int __init
pty_init(void)
751 module_init(pty_init
);