[net-next-2.6.git] / drivers / char / pty.c

/*
 *  linux/drivers/char/pty.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Added support for a Unix98-style ptmx device.
 *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
 *  Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
 *      waiting writers -- Sapan Bhatia <sapan@corewars.org>
 *
 *
 */

#include <linux/module.h>	/* For EXPORT_SYMBOL */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/sysctl.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>

/* These are global because they are accessed in tty_io.c */
#ifdef CONFIG_UNIX98_PTYS
struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
#endif

static void pty_close(struct tty_struct * tty, struct file * filp)
{
	if (!tty)
		return;
	if (tty->driver->subtype == PTY_TYPE_MASTER) {
		if (tty->count > 1)
			printk("master pty_close: count = %d!!\n", tty->count);
	} else {
		if (tty->count > 2)
			return;
	}
	wake_up_interruptible(&tty->read_wait);
	wake_up_interruptible(&tty->write_wait);
	tty->packet = 0;
	if (!tty->link)
		return;
	tty->link->packet = 0;
	set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	wake_up_interruptible(&tty->link->read_wait);
	wake_up_interruptible(&tty->link->write_wait);
	if (tty->driver->subtype == PTY_TYPE_MASTER) {
		set_bit(TTY_OTHER_CLOSED, &tty->flags);
#ifdef CONFIG_UNIX98_PTYS
		if (tty->driver == ptm_driver)
			devpts_pty_kill(tty->index);
#endif
		tty_vhangup(tty->link);
	}
}

/*
 * The unthrottle routine is called by the line discipline to signal
 * that it can receive more characters.  For PTY's, the TTY_THROTTLED
 * flag is always set, to force the line discipline to always call the
 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 
 * characters in the queue.  This is necessary since each time this
 * happens, we need to wake up any sleeping processes that could be
 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
 * for the pty buffer to be drained.
 */
static void pty_unthrottle(struct tty_struct * tty)
{
	struct tty_struct *o_tty = tty->link;

	if (!o_tty)
		return;

	tty_wakeup(o_tty);
	set_bit(TTY_THROTTLED, &tty->flags);
}

/*
 * WSH 05/24/97: modified to 
 *   (1) use space in tty->flip instead of a shared temp buffer
 *	 The flip buffers aren't being used for a pty, so there's lots
 *	 of space available.  The buffer is protected by a per-pty
 *	 semaphore that should almost never come under contention.
 *   (2) avoid redundant copying for cases where count >> receive_room
 * N.B. Calls from user space may now return an error code instead of
 * a count.
 *
 * FIXME: Our pty_write method is called with our ldisc lock held but
 * not our partners. We can't just take the other one blindly without
 * risking deadlocks.
 */
static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
{
	struct tty_struct *to = tty->link;
	int	c;

	if (!to || tty->stopped)
		return 0;

	c = to->receive_room;
	if (c > count)
		c = count;
	to->ldisc.receive_buf(to, buf, NULL, c);
	
	return c;
}

static int pty_write_room(struct tty_struct *tty)
{
	struct tty_struct *to = tty->link;

	if (!to || tty->stopped)
		return 0;

	return to->receive_room;
}

/*
 *	WSH 05/24/97:  Modified for asymmetric MASTER/SLAVE behavior
 *	The chars_in_buffer() value is used by the ldisc select() function 
 *	to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
 *	The pty driver chars_in_buffer() Master/Slave must behave differently:
 *
 *      The Master side needs to allow typed-ahead commands to accumulate
 *      while being canonicalized, so we report "our buffer" as empty until
 *	some threshold is reached, and then report the count. (Any count >
 *	WAKEUP_CHARS is regarded by select() as "full".)  To avoid deadlock 
 *	the count returned must be 0 if no canonical data is available to be 
 *	read. (The N_TTY ldisc.chars_in_buffer now knows this.)
 *  
 *	The Slave side passes all characters in raw mode to the Master side's
 *	buffer where they can be read immediately, so in this case we can
 *	return the true count in the buffer.
 */
static int pty_chars_in_buffer(struct tty_struct *tty)
{
	struct tty_struct *to = tty->link;
	int count;

	/* We should get the line discipline lock for "tty->link" */
	if (!to || !to->ldisc.chars_in_buffer)
		return 0;

	/* The ldisc must report 0 if no characters available to be read */
	count = to->ldisc.chars_in_buffer(to);

	if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;

	/* Master side driver ... if the other side's read buffer is less than 
	 * half full, return 0 to allow writers to proceed; otherwise return
	 * the count.  This leaves a comfortable margin to avoid overflow, 
	 * and still allows half a buffer's worth of typed-ahead commands.
	 */
	return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
}

/* Set the lock flag on a pty */
static int pty_set_lock(struct tty_struct *tty, int __user * arg)
{
	int val;
	if (get_user(val,arg))
		return -EFAULT;
	if (val)
		set_bit(TTY_PTY_LOCK, &tty->flags);
	else
		clear_bit(TTY_PTY_LOCK, &tty->flags);
	return 0;
}

static void pty_flush_buffer(struct tty_struct *tty)
{
	struct tty_struct *to = tty->link;
	
	if (!to)
		return;
	
	if (to->ldisc.flush_buffer)
		to->ldisc.flush_buffer(to);
	
	if (to->packet) {
		tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
		wake_up_interruptible(&to->read_wait);
	}
}

static int pty_open(struct tty_struct *tty, struct file * filp)
{
	int	retval = -ENODEV;

	if (!tty || !tty->link)
		goto out;

	retval = -EIO;
	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
		goto out;
	if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
		goto out;
	if (tty->link->count != 1)
		goto out;

	clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	set_bit(TTY_THROTTLED, &tty->flags);
	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	retval = 0;
out:
	return retval;
}

static void pty_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
        tty->termios->c_cflag &= ~(CSIZE | PARENB);
        tty->termios->c_cflag |= (CS8 | CREAD);
}

static const struct tty_operations pty_ops = {
	.open = pty_open,
	.close = pty_close,
	.write = pty_write,
	.write_room = pty_write_room,
	.flush_buffer = pty_flush_buffer,
	.chars_in_buffer = pty_chars_in_buffer,
	.unthrottle = pty_unthrottle,
	.set_termios = pty_set_termios,
};

/* Traditional BSD devices */
#ifdef CONFIG_LEGACY_PTYS
static struct tty_driver *pty_driver, *pty_slave_driver;

static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
			 unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
		return pty_set_lock(tty, (int __user *) arg);
	}
	return -ENOIOCTLCMD;
}

static void __init legacy_pty_init(void)
{

	pty_driver = alloc_tty_driver(NR_PTYS);
	if (!pty_driver)
		panic("Couldn't allocate pty driver");

	pty_slave_driver = alloc_tty_driver(NR_PTYS);
	if (!pty_slave_driver)
		panic("Couldn't allocate pty slave driver");

	pty_driver->owner = THIS_MODULE;
	pty_driver->driver_name = "pty_master";
	pty_driver->name = "pty";
	pty_driver->major = PTY_MASTER_MAJOR;
	pty_driver->minor_start = 0;
	pty_driver->type = TTY_DRIVER_TYPE_PTY;
	pty_driver->subtype = PTY_TYPE_MASTER;
	pty_driver->init_termios = tty_std_termios;
	pty_driver->init_termios.c_iflag = 0;
	pty_driver->init_termios.c_oflag = 0;
	pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pty_driver->init_termios.c_lflag = 0;
	pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
	pty_driver->other = pty_slave_driver;
	tty_set_operations(pty_driver, &pty_ops);
	pty_driver->ioctl = pty_bsd_ioctl;

	pty_slave_driver->owner = THIS_MODULE;
	pty_slave_driver->driver_name = "pty_slave";
	pty_slave_driver->name = "ttyp";
	pty_slave_driver->major = PTY_SLAVE_MAJOR;
	pty_slave_driver->minor_start = 0;
	pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
	pty_slave_driver->subtype = PTY_TYPE_SLAVE;
	pty_slave_driver->init_termios = tty_std_termios;
	pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
					TTY_DRIVER_REAL_RAW;
	pty_slave_driver->other = pty_driver;
	tty_set_operations(pty_slave_driver, &pty_ops);

	if (tty_register_driver(pty_driver))
		panic("Couldn't register pty driver");
	if (tty_register_driver(pty_slave_driver))
		panic("Couldn't register pty slave driver");
}
#else
static inline void legacy_pty_init(void) { }
#endif

/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
/*
 * sysctl support for setting limits on the number of Unix98 ptys allocated.
 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 */
int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_limit_min = 0;
static int pty_limit_max = NR_UNIX98_PTY_MAX;

ctl_table pty_table[] = {
	{
		.ctl_name	= PTY_MAX,
		.procname	= "max",
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.data		= &pty_limit,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &pty_limit_min,
		.extra2		= &pty_limit_max,
	}, {
		.ctl_name	= PTY_NR,
		.procname	= "nr",
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= &proc_dointvec,
	}, {
		.ctl_name	= 0
	}
};

static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
			    unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
		return pty_set_lock(tty, (int __user *)arg);
	case TIOCGPTN: /* Get PT Number */
		return put_user(tty->index, (unsigned int __user *)arg);
	}

	return -ENOIOCTLCMD;
}

static void __init unix98_pty_init(void)
{
	ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	if (!ptm_driver)
		panic("Couldn't allocate Unix98 ptm driver");
	pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	if (!pts_driver)
		panic("Couldn't allocate Unix98 pts driver");

	ptm_driver->owner = THIS_MODULE;
	ptm_driver->driver_name = "pty_master";
	ptm_driver->name = "ptm";
	ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
	ptm_driver->minor_start = 0;
	ptm_driver->type = TTY_DRIVER_TYPE_PTY;
	ptm_driver->subtype = PTY_TYPE_MASTER;
	ptm_driver->init_termios = tty_std_termios;
	ptm_driver->init_termios.c_iflag = 0;
	ptm_driver->init_termios.c_oflag = 0;
	ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	ptm_driver->init_termios.c_lflag = 0;
	ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
		TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
	ptm_driver->other = pts_driver;
	tty_set_operations(ptm_driver, &pty_ops);
	ptm_driver->ioctl = pty_unix98_ioctl;

	pts_driver->owner = THIS_MODULE;
	pts_driver->driver_name = "pty_slave";
	pts_driver->name = "pts";
	pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
	pts_driver->minor_start = 0;
	pts_driver->type = TTY_DRIVER_TYPE_PTY;
	pts_driver->subtype = PTY_TYPE_SLAVE;
	pts_driver->init_termios = tty_std_termios;
	pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
		TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
	pts_driver->other = ptm_driver;
	tty_set_operations(pts_driver, &pty_ops);
	
	if (tty_register_driver(ptm_driver))
		panic("Couldn't register Unix98 ptm driver");
	if (tty_register_driver(pts_driver))
		panic("Couldn't register Unix98 pts driver");

	pty_table[1].data = &ptm_driver->refcount;
}
#else
static inline void unix98_pty_init(void) { }
#endif

static int __init pty_init(void)
{
	legacy_pty_init();
	unix98_pty_init();
	return 0;
}
module_init(pty_init);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/drivers/char/pty.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	*
	6	* Added support for a Unix98-style ptmx device.
	7	* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
	8	* Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
	9	* waiting writers -- Sapan Bhatia <sapan@corewars.org>
	10	*
	11	*
	12	*/
	13
1da177e4 LT	14	#include <linux/module.h> /* For EXPORT_SYMBOL */
	15
	16	#include <linux/errno.h>
	17	#include <linux/sched.h>
	18	#include <linux/interrupt.h>
	19	#include <linux/tty.h>
	20	#include <linux/tty_flip.h>
	21	#include <linux/fcntl.h>
	22	#include <linux/string.h>
	23	#include <linux/major.h>
	24	#include <linux/mm.h>
	25	#include <linux/init.h>
1da177e4 LT	26	#include <linux/sysctl.h>
	27
	28	#include <asm/uaccess.h>
	29	#include <asm/system.h>
	30	#include <linux/bitops.h>
	31	#include <linux/devpts_fs.h>
	32
	33	/* These are global because they are accessed in tty_io.c */
	34	#ifdef CONFIG_UNIX98_PTYS
	35	struct tty_driver *ptm_driver;
	36	static struct tty_driver *pts_driver;
	37	#endif
	38
	39	static void pty_close(struct tty_struct * tty, struct file * filp)
	40	{
	41	if (!tty)
	42	return;
	43	if (tty->driver->subtype == PTY_TYPE_MASTER) {
	44	if (tty->count > 1)
	45	printk("master pty_close: count = %d!!\n", tty->count);
	46	} else {
	47	if (tty->count > 2)
	48	return;
	49	}
	50	wake_up_interruptible(&tty->read_wait);
	51	wake_up_interruptible(&tty->write_wait);
	52	tty->packet = 0;
	53	if (!tty->link)
	54	return;
	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->index);
	64	#endif
	65	tty_vhangup(tty->link);
	66	}
	67	}
	68
	69	/*
	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.
	78	*/
	79	static void pty_unthrottle(struct tty_struct * tty)
	80	{
	81	struct tty_struct *o_tty = tty->link;
	82
	83	if (!o_tty)
	84	return;
	85
	86	tty_wakeup(o_tty);
	87	set_bit(TTY_THROTTLED, &tty->flags);
	88	}
	89
90	/*
91	* WSH 05/24/97: modified to
92	* (1) use space in tty->flip instead of a shared temp buffer
93	* The flip buffers aren't being used for a pty, so there's lots
94	* of space available. The buffer is protected by a per-pty
95	* semaphore that should almost never come under contention.
96	* (2) avoid redundant copying for cases where count >> receive_room
97	* N.B. Calls from user space may now return an error code instead of
98	* a count.
99	*
100	* FIXME: Our pty_write method is called with our ldisc lock held but
101	* not our partners. We can't just take the other one blindly without
817d6d3b	102	* risking deadlocks.
1da177e4 LT	103	*/
	104	static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
	105	{
	106	struct tty_struct *to = tty->link;
	107	int c;
	108
	109	if (!to \|\| tty->stopped)
	110	return 0;
	111
33f0f88f	112	c = to->receive_room;
1da177e4 LT	113	if (c > count)
	114	c = count;
	115	to->ldisc.receive_buf(to, buf, NULL, c);
	116
	117	return c;
	118	}
	119
	120	static int pty_write_room(struct tty_struct *tty)
	121	{
	122	struct tty_struct *to = tty->link;
	123
	124	if (!to \|\| tty->stopped)
	125	return 0;
	126
33f0f88f	127	return to->receive_room;
1da177e4 LT	128	}
	129
	130	/*
	131	* WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
	132	* The chars_in_buffer() value is used by the ldisc select() function
	133	* to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
	134	* The pty driver chars_in_buffer() Master/Slave must behave differently:
	135	*
	136	* The Master side needs to allow typed-ahead commands to accumulate
	137	* while being canonicalized, so we report "our buffer" as empty until
	138	* some threshold is reached, and then report the count. (Any count >
	139	* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
	140	* the count returned must be 0 if no canonical data is available to be
	141	* read. (The N_TTY ldisc.chars_in_buffer now knows this.)
	142	*
	143	* The Slave side passes all characters in raw mode to the Master side's
	144	* buffer where they can be read immediately, so in this case we can
	145	* return the true count in the buffer.
	146	*/
	147	static int pty_chars_in_buffer(struct tty_struct *tty)
	148	{
	149	struct tty_struct *to = tty->link;
1da177e4 LT	150	int count;
	151
	152	/* We should get the line discipline lock for "tty->link" */
ff55fe20	153	if (!to \|\| !to->ldisc.chars_in_buffer)
1da177e4 LT	154	return 0;
	155
	156	/* The ldisc must report 0 if no characters available to be read */
ff55fe20	157	count = to->ldisc.chars_in_buffer(to);
1da177e4 LT	158
	159	if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
	160
	161	/* Master side driver ... if the other side's read buffer is less than
	162	* half full, return 0 to allow writers to proceed; otherwise return
	163	* the count. This leaves a comfortable margin to avoid overflow,
	164	* and still allows half a buffer's worth of typed-ahead commands.
	165	*/
	166	return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
	167	}
	168
	169	/* Set the lock flag on a pty */
	170	static int pty_set_lock(struct tty_struct tty, int __user arg)
	171	{
	172	int val;
	173	if (get_user(val,arg))
	174	return -EFAULT;
	175	if (val)
	176	set_bit(TTY_PTY_LOCK, &tty->flags);
	177	else
	178	clear_bit(TTY_PTY_LOCK, &tty->flags);
	179	return 0;
	180	}
	181
	182	static void pty_flush_buffer(struct tty_struct *tty)
	183	{
	184	struct tty_struct *to = tty->link;
	185
	186	if (!to)
	187	return;
	188
	189	if (to->ldisc.flush_buffer)
	190	to->ldisc.flush_buffer(to);
	191
	192	if (to->packet) {
	193	tty->ctrl_status \|= TIOCPKT_FLUSHWRITE;
	194	wake_up_interruptible(&to->read_wait);
	195	}
	196	}
	197
	198	static int pty_open(struct tty_struct tty, struct file filp)
	199	{
	200	int retval = -ENODEV;
	201
	202	if (!tty \|\| !tty->link)
	203	goto out;
	204
	205	retval = -EIO;
	206	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
	207	goto out;
	208	if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
	209	goto out;
	210	if (tty->link->count != 1)
	211	goto out;
	212
	213	clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	214	set_bit(TTY_THROTTLED, &tty->flags);
	215	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	216	retval = 0;
	217	out:
	218	return retval;
	219	}
	220
	221	static void pty_set_termios(struct tty_struct tty, struct termios old_termios)
222	{
223	tty->termios->c_cflag &= ~(CSIZE \| PARENB);
224	tty->termios->c_cflag \|= (CS8 \| CREAD);
225	}
226
b68e31d0	227	static const struct tty_operations pty_ops = {
1da177e4 LT	228	.open = pty_open,
	229	.close = pty_close,
	230	.write = pty_write,
	231	.write_room = pty_write_room,
	232	.flush_buffer = pty_flush_buffer,
	233	.chars_in_buffer = pty_chars_in_buffer,
	234	.unthrottle = pty_unthrottle,
	235	.set_termios = pty_set_termios,
	236	};
	237
	238	/* Traditional BSD devices */
	239	#ifdef CONFIG_LEGACY_PTYS
	240	static struct tty_driver pty_driver, pty_slave_driver;
	241
	242	static int pty_bsd_ioctl(struct tty_struct tty, struct file file,
	243	unsigned int cmd, unsigned long arg)
	244	{
	245	switch (cmd) {
	246	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
	247	return pty_set_lock(tty, (int __user *) arg);
	248	}
	249	return -ENOIOCTLCMD;
	250	}
	251
	252	static void __init legacy_pty_init(void)
	253	{
	254
	255	pty_driver = alloc_tty_driver(NR_PTYS);
	256	if (!pty_driver)
	257	panic("Couldn't allocate pty driver");
	258
	259	pty_slave_driver = alloc_tty_driver(NR_PTYS);
	260	if (!pty_slave_driver)
	261	panic("Couldn't allocate pty slave driver");
	262
	263	pty_driver->owner = THIS_MODULE;
	264	pty_driver->driver_name = "pty_master";
	265	pty_driver->name = "pty";
1da177e4 LT	266	pty_driver->major = PTY_MASTER_MAJOR;
	267	pty_driver->minor_start = 0;
	268	pty_driver->type = TTY_DRIVER_TYPE_PTY;
	269	pty_driver->subtype = PTY_TYPE_MASTER;
	270	pty_driver->init_termios = tty_std_termios;
	271	pty_driver->init_termios.c_iflag = 0;
	272	pty_driver->init_termios.c_oflag = 0;
	273	pty_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	274	pty_driver->init_termios.c_lflag = 0;
	275	pty_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW;
	276	pty_driver->other = pty_slave_driver;
	277	tty_set_operations(pty_driver, &pty_ops);
	278	pty_driver->ioctl = pty_bsd_ioctl;
	279
	280	pty_slave_driver->owner = THIS_MODULE;
	281	pty_slave_driver->driver_name = "pty_slave";
	282	pty_slave_driver->name = "ttyp";
1da177e4 LT	283	pty_slave_driver->major = PTY_SLAVE_MAJOR;
	284	pty_slave_driver->minor_start = 0;
	285	pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
	286	pty_slave_driver->subtype = PTY_TYPE_SLAVE;
	287	pty_slave_driver->init_termios = tty_std_termios;
	288	pty_slave_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	289	pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS \|
	290	TTY_DRIVER_REAL_RAW;
	291	pty_slave_driver->other = pty_driver;
	292	tty_set_operations(pty_slave_driver, &pty_ops);
	293
	294	if (tty_register_driver(pty_driver))
	295	panic("Couldn't register pty driver");
	296	if (tty_register_driver(pty_slave_driver))
	297	panic("Couldn't register pty slave driver");
	298	}
	299	#else
	300	static inline void legacy_pty_init(void) { }
	301	#endif
	302
	303	/* Unix98 devices */
	304	#ifdef CONFIG_UNIX98_PTYS
	305	/*
	306	* sysctl support for setting limits on the number of Unix98 ptys allocated.
	307	* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
	308	*/
	309	int pty_limit = NR_UNIX98_PTY_DEFAULT;
	310	static int pty_limit_min = 0;
	311	static int pty_limit_max = NR_UNIX98_PTY_MAX;
	312
	313	ctl_table pty_table[] = {
	314	{
	315	.ctl_name = PTY_MAX,
	316	.procname = "max",
	317	.maxlen = sizeof(int),
	318	.mode = 0644,
	319	.data = &pty_limit,
	320	.proc_handler = &proc_dointvec_minmax,
	321	.strategy = &sysctl_intvec,
	322	.extra1 = &pty_limit_min,
	323	.extra2 = &pty_limit_max,
	324	}, {
	325	.ctl_name = PTY_NR,
	326	.procname = "nr",
	327	.maxlen = sizeof(int),
	328	.mode = 0444,
	329	.proc_handler = &proc_dointvec,
	330	}, {
	331	.ctl_name = 0
	332	}
	333	};
	334
	335	static int pty_unix98_ioctl(struct tty_struct tty, struct file file,
	336	unsigned int cmd, unsigned long arg)
	337	{
	338	switch (cmd) {
	339	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
	340	return pty_set_lock(tty, (int __user *)arg);
	341	case TIOCGPTN: /* Get PT Number */
	342	return put_user(tty->index, (unsigned int __user *)arg);
	343	}
	344
	345	return -ENOIOCTLCMD;
	346	}
347
348	static void __init unix98_pty_init(void)
349	{
1da177e4 LT	350	ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	351	if (!ptm_driver)
	352	panic("Couldn't allocate Unix98 ptm driver");
	353	pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	354	if (!pts_driver)
	355	panic("Couldn't allocate Unix98 pts driver");
	356
	357	ptm_driver->owner = THIS_MODULE;
	358	ptm_driver->driver_name = "pty_master";
	359	ptm_driver->name = "ptm";
	360	ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
	361	ptm_driver->minor_start = 0;
	362	ptm_driver->type = TTY_DRIVER_TYPE_PTY;
	363	ptm_driver->subtype = PTY_TYPE_MASTER;
	364	ptm_driver->init_termios = tty_std_termios;
	365	ptm_driver->init_termios.c_iflag = 0;
	366	ptm_driver->init_termios.c_oflag = 0;
	367	ptm_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	368	ptm_driver->init_termios.c_lflag = 0;
	369	ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW \|
331b8319	370	TTY_DRIVER_DYNAMIC_DEV \| TTY_DRIVER_DEVPTS_MEM;
1da177e4 LT	371	ptm_driver->other = pts_driver;
	372	tty_set_operations(ptm_driver, &pty_ops);
	373	ptm_driver->ioctl = pty_unix98_ioctl;
	374
	375	pts_driver->owner = THIS_MODULE;
	376	pts_driver->driver_name = "pty_slave";
	377	pts_driver->name = "pts";
	378	pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
	379	pts_driver->minor_start = 0;
	380	pts_driver->type = TTY_DRIVER_TYPE_PTY;
	381	pts_driver->subtype = PTY_TYPE_SLAVE;
	382	pts_driver->init_termios = tty_std_termios;
	383	pts_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	384	pts_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW \|
331b8319	385	TTY_DRIVER_DYNAMIC_DEV \| TTY_DRIVER_DEVPTS_MEM;
1da177e4 LT	386	pts_driver->other = ptm_driver;
	387	tty_set_operations(pts_driver, &pty_ops);
	388
	389	if (tty_register_driver(ptm_driver))
	390	panic("Couldn't register Unix98 ptm driver");
	391	if (tty_register_driver(pts_driver))
	392	panic("Couldn't register Unix98 pts driver");
	393
	394	pty_table[1].data = &ptm_driver->refcount;
	395	}
	396	#else
	397	static inline void unix98_pty_init(void) { }
	398	#endif
	399
	400	static int __init pty_init(void)
	401	{
	402	legacy_pty_init();
	403	unix98_pty_init();
	404	return 0;
	405	}
	406	module_init(pty_init);