2 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Added support for a Unix98-style ptmx device.
5 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
7 * When reading this code see also fs/devpts. In particular note that the
8 * driver_data field is used by the devpts side as a binding to the devpts
12 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/interrupt.h>
16 #include <linux/tty.h>
17 #include <linux/tty_flip.h>
18 #include <linux/fcntl.h>
19 #include <linux/sched.h>
20 #include <linux/string.h>
21 #include <linux/major.h>
23 #include <linux/init.h>
24 #include <linux/device.h>
25 #include <linux/uaccess.h>
26 #include <linux/bitops.h>
27 #include <linux/devpts_fs.h>
28 #include <linux/slab.h>
29 #include <linux/mutex.h>
32 #ifdef CONFIG_UNIX98_PTYS
33 static struct tty_driver
*ptm_driver
;
34 static struct tty_driver
*pts_driver
;
35 static DEFINE_MUTEX(devpts_mutex
);
38 static void pty_close(struct tty_struct
*tty
, struct file
*filp
)
41 if (tty
->driver
->subtype
== PTY_TYPE_MASTER
)
42 WARN_ON(tty
->count
> 1);
47 wake_up_interruptible(&tty
->read_wait
);
48 wake_up_interruptible(&tty
->write_wait
);
50 /* Review - krefs on tty_link ?? */
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 mutex_lock(&devpts_mutex
);
62 devpts_pty_kill(tty
->link
);
63 mutex_unlock(&devpts_mutex
);
67 tty_vhangup(tty
->link
);
73 * The unthrottle routine is called by the line discipline to signal
74 * that it can receive more characters. For PTY's, the TTY_THROTTLED
75 * flag is always set, to force the line discipline to always call the
76 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
77 * characters in the queue. This is necessary since each time this
78 * happens, we need to wake up any sleeping processes that could be
79 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
80 * for the pty buffer to be drained.
82 static void pty_unthrottle(struct tty_struct
*tty
)
84 tty_wakeup(tty
->link
);
85 set_bit(TTY_THROTTLED
, &tty
->flags
);
89 * pty_space - report space left for writing
90 * @to: tty we are writing into
92 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
93 * allows a lot of overspill room for echo and other fun messes to
97 static int pty_space(struct tty_struct
*to
)
99 int n
= 8192 - to
->buf
.memory_used
;
106 * pty_write - write to a pty
107 * @tty: the tty we write from
108 * @buf: kernel buffer of data
109 * @count: bytes to write
111 * Our "hardware" write method. Data is coming from the ldisc which
112 * may be in a non sleeping state. We simply throw this at the other
113 * end of the link as if we were an IRQ handler receiving stuff for
114 * the other side of the pty/tty pair.
117 static int pty_write(struct tty_struct
*tty
, const unsigned char *buf
, int c
)
119 struct tty_struct
*to
= tty
->link
;
125 /* Stuff the data into the input queue of the other end */
126 c
= tty_insert_flip_string(to
, buf
, c
);
129 tty_flip_buffer_push(to
);
137 * pty_write_room - write space
138 * @tty: tty we are writing from
140 * Report how many bytes the ldisc can send into the queue for
144 static int pty_write_room(struct tty_struct
*tty
)
148 return pty_space(tty
->link
);
152 * pty_chars_in_buffer - characters currently in our tx queue
155 * Report how much we have in the transmit queue. As everything is
156 * instantly at the other end this is easy to implement.
159 static int pty_chars_in_buffer(struct tty_struct
*tty
)
164 /* Set the lock flag on a pty */
165 static int pty_set_lock(struct tty_struct
*tty
, int __user
*arg
)
168 if (get_user(val
, arg
))
171 set_bit(TTY_PTY_LOCK
, &tty
->flags
);
173 clear_bit(TTY_PTY_LOCK
, &tty
->flags
);
177 /* Send a signal to the slave */
178 static int pty_signal(struct tty_struct
*tty
, int sig
)
184 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
185 pgrp
= get_pid(tty
->link
->pgrp
);
186 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
188 kill_pgrp(pgrp
, sig
, 1);
194 static void pty_flush_buffer(struct tty_struct
*tty
)
196 struct tty_struct
*to
= tty
->link
;
201 /* tty_buffer_flush(to); FIXME */
203 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
204 tty
->ctrl_status
|= TIOCPKT_FLUSHWRITE
;
205 wake_up_interruptible(&to
->read_wait
);
206 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
210 static int pty_open(struct tty_struct
*tty
, struct file
*filp
)
212 int retval
= -ENODEV
;
214 if (!tty
|| !tty
->link
)
218 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
220 if (test_bit(TTY_PTY_LOCK
, &tty
->link
->flags
))
222 if (tty
->link
->count
!= 1)
225 clear_bit(TTY_OTHER_CLOSED
, &tty
->link
->flags
);
226 set_bit(TTY_THROTTLED
, &tty
->flags
);
232 static void pty_set_termios(struct tty_struct
*tty
,
233 struct ktermios
*old_termios
)
235 tty
->termios
.c_cflag
&= ~(CSIZE
| PARENB
);
236 tty
->termios
.c_cflag
|= (CS8
| CREAD
);
240 * pty_do_resize - resize event
241 * @tty: tty being resized
242 * @ws: window size being set.
244 * Update the termios variables and send the necessary signals to
245 * peform a terminal resize correctly
248 int pty_resize(struct tty_struct
*tty
, struct winsize
*ws
)
250 struct pid
*pgrp
, *rpgrp
;
252 struct tty_struct
*pty
= tty
->link
;
254 /* For a PTY we need to lock the tty side */
255 mutex_lock(&tty
->termios_mutex
);
256 if (!memcmp(ws
, &tty
->winsize
, sizeof(*ws
)))
259 /* Get the PID values and reference them so we can
260 avoid holding the tty ctrl lock while sending signals.
261 We need to lock these individually however. */
263 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
264 pgrp
= get_pid(tty
->pgrp
);
265 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
267 spin_lock_irqsave(&pty
->ctrl_lock
, flags
);
268 rpgrp
= get_pid(pty
->pgrp
);
269 spin_unlock_irqrestore(&pty
->ctrl_lock
, flags
);
272 kill_pgrp(pgrp
, SIGWINCH
, 1);
273 if (rpgrp
!= pgrp
&& rpgrp
)
274 kill_pgrp(rpgrp
, SIGWINCH
, 1);
280 pty
->winsize
= *ws
; /* Never used so will go away soon */
282 mutex_unlock(&tty
->termios_mutex
);
287 * pty_common_install - set up the pty pair
288 * @driver: the pty driver
289 * @tty: the tty being instantiated
290 * @bool: legacy, true if this is BSD style
292 * Perform the initial set up for the tty/pty pair. Called from the
293 * tty layer when the port is first opened.
295 * Locking: the caller must hold the tty_mutex
297 static int pty_common_install(struct tty_driver
*driver
, struct tty_struct
*tty
,
300 struct tty_struct
*o_tty
;
301 struct tty_port
*ports
[2];
302 int idx
= tty
->index
;
303 int retval
= -ENOMEM
;
305 o_tty
= alloc_tty_struct();
306 ports
[0] = kmalloc(sizeof **ports
, GFP_KERNEL
);
307 ports
[1] = kmalloc(sizeof **ports
, GFP_KERNEL
);
308 if (!o_tty
|| !ports
[0] || !ports
[1])
310 if (!try_module_get(driver
->other
->owner
)) {
311 /* This cannot in fact currently happen */
314 initialize_tty_struct(o_tty
, driver
->other
, idx
);
317 /* We always use new tty termios data so we can do this
319 retval
= tty_init_termios(tty
);
323 retval
= tty_init_termios(o_tty
);
325 goto err_free_termios
;
327 driver
->other
->ttys
[idx
] = o_tty
;
328 driver
->ttys
[idx
] = tty
;
330 memset(&tty
->termios_locked
, 0, sizeof(tty
->termios_locked
));
331 tty
->termios
= driver
->init_termios
;
332 memset(&o_tty
->termios_locked
, 0, sizeof(tty
->termios_locked
));
333 o_tty
->termios
= driver
->other
->init_termios
;
337 * Everything allocated ... set up the o_tty structure.
339 tty_driver_kref_get(driver
->other
);
340 if (driver
->subtype
== PTY_TYPE_MASTER
)
342 /* Establish the links in both directions */
345 tty_port_init(ports
[0]);
346 tty_port_init(ports
[1]);
347 o_tty
->port
= ports
[0];
348 tty
->port
= ports
[1];
350 tty_driver_kref_get(driver
);
355 tty_free_termios(tty
);
357 deinitialize_tty_struct(o_tty
);
358 module_put(o_tty
->driver
->owner
);
362 free_tty_struct(o_tty
);
366 static void pty_cleanup(struct tty_struct
*tty
)
371 /* Traditional BSD devices */
372 #ifdef CONFIG_LEGACY_PTYS
374 static int pty_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
376 return pty_common_install(driver
, tty
, true);
379 static void pty_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
381 struct tty_struct
*pair
= tty
->link
;
382 driver
->ttys
[tty
->index
] = NULL
;
384 pair
->driver
->ttys
[pair
->index
] = NULL
;
387 static int pty_bsd_ioctl(struct tty_struct
*tty
,
388 unsigned int cmd
, unsigned long arg
)
391 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
392 return pty_set_lock(tty
, (int __user
*) arg
);
393 case TIOCSIG
: /* Send signal to other side of pty */
394 return pty_signal(tty
, (int) arg
);
399 static int legacy_count
= CONFIG_LEGACY_PTY_COUNT
;
400 module_param(legacy_count
, int, 0);
403 * The master side of a pty can do TIOCSPTLCK and thus
406 static const struct tty_operations master_pty_ops_bsd
= {
407 .install
= pty_install
,
411 .write_room
= pty_write_room
,
412 .flush_buffer
= pty_flush_buffer
,
413 .chars_in_buffer
= pty_chars_in_buffer
,
414 .unthrottle
= pty_unthrottle
,
415 .set_termios
= pty_set_termios
,
416 .ioctl
= pty_bsd_ioctl
,
417 .cleanup
= pty_cleanup
,
418 .resize
= pty_resize
,
422 static const struct tty_operations slave_pty_ops_bsd
= {
423 .install
= pty_install
,
427 .write_room
= pty_write_room
,
428 .flush_buffer
= pty_flush_buffer
,
429 .chars_in_buffer
= pty_chars_in_buffer
,
430 .unthrottle
= pty_unthrottle
,
431 .set_termios
= pty_set_termios
,
432 .cleanup
= pty_cleanup
,
433 .resize
= pty_resize
,
437 static void __init
legacy_pty_init(void)
439 struct tty_driver
*pty_driver
, *pty_slave_driver
;
441 if (legacy_count
<= 0)
444 pty_driver
= alloc_tty_driver(legacy_count
);
446 panic("Couldn't allocate pty driver");
448 pty_slave_driver
= alloc_tty_driver(legacy_count
);
449 if (!pty_slave_driver
)
450 panic("Couldn't allocate pty slave driver");
452 pty_driver
->driver_name
= "pty_master";
453 pty_driver
->name
= "pty";
454 pty_driver
->major
= PTY_MASTER_MAJOR
;
455 pty_driver
->minor_start
= 0;
456 pty_driver
->type
= TTY_DRIVER_TYPE_PTY
;
457 pty_driver
->subtype
= PTY_TYPE_MASTER
;
458 pty_driver
->init_termios
= tty_std_termios
;
459 pty_driver
->init_termios
.c_iflag
= 0;
460 pty_driver
->init_termios
.c_oflag
= 0;
461 pty_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
462 pty_driver
->init_termios
.c_lflag
= 0;
463 pty_driver
->init_termios
.c_ispeed
= 38400;
464 pty_driver
->init_termios
.c_ospeed
= 38400;
465 pty_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
;
466 pty_driver
->other
= pty_slave_driver
;
467 tty_set_operations(pty_driver
, &master_pty_ops_bsd
);
469 pty_slave_driver
->driver_name
= "pty_slave";
470 pty_slave_driver
->name
= "ttyp";
471 pty_slave_driver
->major
= PTY_SLAVE_MAJOR
;
472 pty_slave_driver
->minor_start
= 0;
473 pty_slave_driver
->type
= TTY_DRIVER_TYPE_PTY
;
474 pty_slave_driver
->subtype
= PTY_TYPE_SLAVE
;
475 pty_slave_driver
->init_termios
= tty_std_termios
;
476 pty_slave_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
477 pty_slave_driver
->init_termios
.c_ispeed
= 38400;
478 pty_slave_driver
->init_termios
.c_ospeed
= 38400;
479 pty_slave_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
|
481 pty_slave_driver
->other
= pty_driver
;
482 tty_set_operations(pty_slave_driver
, &slave_pty_ops_bsd
);
484 if (tty_register_driver(pty_driver
))
485 panic("Couldn't register pty driver");
486 if (tty_register_driver(pty_slave_driver
))
487 panic("Couldn't register pty slave driver");
490 static inline void legacy_pty_init(void) { }
494 #ifdef CONFIG_UNIX98_PTYS
496 static struct cdev ptmx_cdev
;
498 static int pty_unix98_ioctl(struct tty_struct
*tty
,
499 unsigned int cmd
, unsigned long arg
)
502 case TIOCSPTLCK
: /* Set PT Lock (disallow slave open) */
503 return pty_set_lock(tty
, (int __user
*)arg
);
504 case TIOCGPTN
: /* Get PT Number */
505 return put_user(tty
->index
, (unsigned int __user
*)arg
);
506 case TIOCSIG
: /* Send signal to other side of pty */
507 return pty_signal(tty
, (int) arg
);
514 * ptm_unix98_lookup - find a pty master
515 * @driver: ptm driver
518 * Look up a pty master device. Called under the tty_mutex for now.
519 * This provides our locking.
522 static struct tty_struct
*ptm_unix98_lookup(struct tty_driver
*driver
,
523 struct inode
*ptm_inode
, int idx
)
525 /* Master must be open via /dev/ptmx */
526 return ERR_PTR(-EIO
);
530 * pts_unix98_lookup - find a pty slave
531 * @driver: pts driver
534 * Look up a pty master device. Called under the tty_mutex for now.
535 * This provides our locking for the tty pointer.
538 static struct tty_struct
*pts_unix98_lookup(struct tty_driver
*driver
,
539 struct inode
*pts_inode
, int idx
)
541 struct tty_struct
*tty
;
543 mutex_lock(&devpts_mutex
);
544 tty
= devpts_get_tty(pts_inode
, idx
);
545 mutex_unlock(&devpts_mutex
);
546 /* Master must be open before slave */
548 return ERR_PTR(-EIO
);
552 /* We have no need to install and remove our tty objects as devpts does all
555 static int pty_unix98_install(struct tty_driver
*driver
, struct tty_struct
*tty
)
557 return pty_common_install(driver
, tty
, false);
560 static void pty_unix98_remove(struct tty_driver
*driver
, struct tty_struct
*tty
)
564 static const struct tty_operations ptm_unix98_ops
= {
565 .lookup
= ptm_unix98_lookup
,
566 .install
= pty_unix98_install
,
567 .remove
= pty_unix98_remove
,
571 .write_room
= pty_write_room
,
572 .flush_buffer
= pty_flush_buffer
,
573 .chars_in_buffer
= pty_chars_in_buffer
,
574 .unthrottle
= pty_unthrottle
,
575 .set_termios
= pty_set_termios
,
576 .ioctl
= pty_unix98_ioctl
,
577 .resize
= pty_resize
,
578 .cleanup
= pty_cleanup
581 static const struct tty_operations pty_unix98_ops
= {
582 .lookup
= pts_unix98_lookup
,
583 .install
= pty_unix98_install
,
584 .remove
= pty_unix98_remove
,
588 .write_room
= pty_write_room
,
589 .flush_buffer
= pty_flush_buffer
,
590 .chars_in_buffer
= pty_chars_in_buffer
,
591 .unthrottle
= pty_unthrottle
,
592 .set_termios
= pty_set_termios
,
593 .cleanup
= pty_cleanup
,
597 * ptmx_open - open a unix 98 pty master
598 * @inode: inode of device file
599 * @filp: file pointer to tty
601 * Allocate a unix98 pty master device from the ptmx driver.
603 * Locking: tty_mutex protects the init_dev work. tty->count should
605 * allocated_ptys_lock handles the list of free pty numbers
608 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
610 struct tty_struct
*tty
;
614 nonseekable_open(inode
, filp
);
616 retval
= tty_alloc_file(filp
);
620 /* find a device that is not in use. */
621 mutex_lock(&devpts_mutex
);
622 index
= devpts_new_index(inode
);
628 mutex_unlock(&devpts_mutex
);
630 mutex_lock(&tty_mutex
);
631 tty
= tty_init_dev(ptm_driver
, index
);
634 retval
= PTR_ERR(tty
);
638 /* The tty returned here is locked so we can safely
640 mutex_unlock(&tty_mutex
);
642 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
644 tty_add_file(tty
, filp
);
646 retval
= devpts_pty_new(inode
, tty
->link
);
650 retval
= ptm_driver
->ops
->open(tty
, filp
);
658 tty_release(inode
, filp
);
661 mutex_unlock(&tty_mutex
);
662 devpts_kill_index(inode
, index
);
664 mutex_unlock(&devpts_mutex
);
669 static struct file_operations ptmx_fops
;
671 static void __init
unix98_pty_init(void)
673 ptm_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
675 panic("Couldn't allocate Unix98 ptm driver");
676 pts_driver
= alloc_tty_driver(NR_UNIX98_PTY_MAX
);
678 panic("Couldn't allocate Unix98 pts driver");
680 ptm_driver
->driver_name
= "pty_master";
681 ptm_driver
->name
= "ptm";
682 ptm_driver
->major
= UNIX98_PTY_MASTER_MAJOR
;
683 ptm_driver
->minor_start
= 0;
684 ptm_driver
->type
= TTY_DRIVER_TYPE_PTY
;
685 ptm_driver
->subtype
= PTY_TYPE_MASTER
;
686 ptm_driver
->init_termios
= tty_std_termios
;
687 ptm_driver
->init_termios
.c_iflag
= 0;
688 ptm_driver
->init_termios
.c_oflag
= 0;
689 ptm_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
690 ptm_driver
->init_termios
.c_lflag
= 0;
691 ptm_driver
->init_termios
.c_ispeed
= 38400;
692 ptm_driver
->init_termios
.c_ospeed
= 38400;
693 ptm_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
694 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
695 ptm_driver
->other
= pts_driver
;
696 tty_set_operations(ptm_driver
, &ptm_unix98_ops
);
698 pts_driver
->driver_name
= "pty_slave";
699 pts_driver
->name
= "pts";
700 pts_driver
->major
= UNIX98_PTY_SLAVE_MAJOR
;
701 pts_driver
->minor_start
= 0;
702 pts_driver
->type
= TTY_DRIVER_TYPE_PTY
;
703 pts_driver
->subtype
= PTY_TYPE_SLAVE
;
704 pts_driver
->init_termios
= tty_std_termios
;
705 pts_driver
->init_termios
.c_cflag
= B38400
| CS8
| CREAD
;
706 pts_driver
->init_termios
.c_ispeed
= 38400;
707 pts_driver
->init_termios
.c_ospeed
= 38400;
708 pts_driver
->flags
= TTY_DRIVER_RESET_TERMIOS
| TTY_DRIVER_REAL_RAW
|
709 TTY_DRIVER_DYNAMIC_DEV
| TTY_DRIVER_DEVPTS_MEM
;
710 pts_driver
->other
= ptm_driver
;
711 tty_set_operations(pts_driver
, &pty_unix98_ops
);
713 if (tty_register_driver(ptm_driver
))
714 panic("Couldn't register Unix98 ptm driver");
715 if (tty_register_driver(pts_driver
))
716 panic("Couldn't register Unix98 pts driver");
718 /* Now create the /dev/ptmx special device */
719 tty_default_fops(&ptmx_fops
);
720 ptmx_fops
.open
= ptmx_open
;
722 cdev_init(&ptmx_cdev
, &ptmx_fops
);
723 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
724 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
725 panic("Couldn't register /dev/ptmx driver\n");
726 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), NULL
, "ptmx");
730 static inline void unix98_pty_init(void) { }
733 static int __init
pty_init(void)
739 module_init(pty_init
);