[linux-2.6-block.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/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.ops->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.ops->chars_in_buffer)
		return 0;

	/* The ldisc must report 0 if no characters available to be read */
	count = to->ldisc.ops->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;
	unsigned long flags;
	
	if (!to)
		return;
	
	if (to->ldisc.ops->flush_buffer)
		to->ldisc.ops->flush_buffer(to);
	
	if (to->packet) {
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
		wake_up_interruptible(&to->read_wait);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	}
}

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 ktermios *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 int legacy_count = CONFIG_LEGACY_PTY_COUNT;
module_param(legacy_count, int, 0);

static const struct tty_operations pty_ops_bsd = {
	.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,
	.ioctl = pty_bsd_ioctl,
};

static void __init legacy_pty_init(void)
{
	if (legacy_count <= 0)
		return;

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

	pty_slave_driver = alloc_tty_driver(legacy_count);
	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->init_termios.c_ispeed = 38400;
	pty_driver->init_termios.c_ospeed = 38400;
	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_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->init_termios.c_ispeed = 38400;
	pty_slave_driver->init_termios.c_ospeed = 38400;
	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;

static struct 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 struct ctl_table pty_kern_table[] = {
	{
		.ctl_name	= KERN_PTY,
		.procname	= "pty",
		.mode		= 0555,
		.child		= pty_table,
	},
	{}
};

static struct ctl_table pty_root_table[] = {
	{
		.ctl_name	= CTL_KERN,
		.procname	= "kernel",
		.mode		= 0555,
		.child		= pty_kern_table,
	},
	{}
};


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 const struct tty_operations pty_unix98_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,
	.ioctl = pty_unix98_ioctl
};


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->init_termios.c_ispeed = 38400;
	ptm_driver->init_termios.c_ospeed = 38400;
	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_unix98_ops);

	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->init_termios.c_ispeed = 38400;
	pts_driver->init_termios.c_ospeed = 38400;
	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;
	register_sysctl_table(pty_root_table);
}
#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>
1da177e4 LT	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>
	23	#include <linux/mm.h>
	24	#include <linux/init.h>
1da177e4 LT	25	#include <linux/sysctl.h>
	26
	27	#include <asm/uaccess.h>
	28	#include <asm/system.h>
	29	#include <linux/bitops.h>
	30	#include <linux/devpts_fs.h>
	31
	32	/* These are global because they are accessed in tty_io.c */
	33	#ifdef CONFIG_UNIX98_PTYS
	34	struct tty_driver *ptm_driver;
	35	static struct tty_driver *pts_driver;
	36	#endif
	37
	38	static void pty_close(struct tty_struct * tty, struct file * filp)
	39	{
	40	if (!tty)
	41	return;
	42	if (tty->driver->subtype == PTY_TYPE_MASTER) {
	43	if (tty->count > 1)
	44	printk("master pty_close: count = %d!!\n", tty->count);
	45	} else {
	46	if (tty->count > 2)
	47	return;
	48	}
	49	wake_up_interruptible(&tty->read_wait);
	50	wake_up_interruptible(&tty->write_wait);
	51	tty->packet = 0;
	52	if (!tty->link)
	53	return;
	54	tty->link->packet = 0;
	55	set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	56	wake_up_interruptible(&tty->link->read_wait);
	57	wake_up_interruptible(&tty->link->write_wait);
	58	if (tty->driver->subtype == PTY_TYPE_MASTER) {
	59	set_bit(TTY_OTHER_CLOSED, &tty->flags);
	60	#ifdef CONFIG_UNIX98_PTYS
	61	if (tty->driver == ptm_driver)
	62	devpts_pty_kill(tty->index);
	63	#endif
	64	tty_vhangup(tty->link);
	65	}
	66	}
	67
	68	/*
	69	* The unthrottle routine is called by the line discipline to signal
	70	* that it can receive more characters. For PTY's, the TTY_THROTTLED
	71	* flag is always set, to force the line discipline to always call the
	72	* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
	73	* characters in the queue. This is necessary since each time this
	74	* happens, we need to wake up any sleeping processes that could be
	75	* (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
	76	* for the pty buffer to be drained.
	77	*/
	78	static void pty_unthrottle(struct tty_struct * tty)
	79	{
	80	struct tty_struct *o_tty = tty->link;
	81
	82	if (!o_tty)
	83	return;
	84
	85	tty_wakeup(o_tty);
	86	set_bit(TTY_THROTTLED, &tty->flags);
	87	}
	88
89	/*
90	* WSH 05/24/97: modified to
91	* (1) use space in tty->flip instead of a shared temp buffer
92	* The flip buffers aren't being used for a pty, so there's lots
93	* of space available. The buffer is protected by a per-pty
94	* semaphore that should almost never come under contention.
95	* (2) avoid redundant copying for cases where count >> receive_room
96	* N.B. Calls from user space may now return an error code instead of
97	* a count.
98	*
99	* FIXME: Our pty_write method is called with our ldisc lock held but
100	* not our partners. We can't just take the other one blindly without
817d6d3b	101	* risking deadlocks.
1da177e4 LT	102	*/
	103	static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
	104	{
	105	struct tty_struct *to = tty->link;
	106	int c;
	107
	108	if (!to \|\| tty->stopped)
	109	return 0;
	110
33f0f88f	111	c = to->receive_room;
1da177e4 LT	112	if (c > count)
1da177e4 LT	113	c = count;
a352def2	114	to->ldisc.ops->receive_buf(to, buf, NULL, c);
1da177e4 LT	115
	116	return c;
	117	}
	118
	119	static int pty_write_room(struct tty_struct *tty)
	120	{
	121	struct tty_struct *to = tty->link;
	122
	123	if (!to \|\| tty->stopped)
	124	return 0;
	125
33f0f88f	126	return to->receive_room;
1da177e4 LT	127	}
	128
	129	/*
	130	* WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
	131	* The chars_in_buffer() value is used by the ldisc select() function
	132	* to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
	133	* The pty driver chars_in_buffer() Master/Slave must behave differently:
	134	*
	135	* The Master side needs to allow typed-ahead commands to accumulate
	136	* while being canonicalized, so we report "our buffer" as empty until
	137	* some threshold is reached, and then report the count. (Any count >
	138	* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
	139	* the count returned must be 0 if no canonical data is available to be
	140	* read. (The N_TTY ldisc.chars_in_buffer now knows this.)
	141	*
	142	* The Slave side passes all characters in raw mode to the Master side's
	143	* buffer where they can be read immediately, so in this case we can
	144	* return the true count in the buffer.
	145	*/
	146	static int pty_chars_in_buffer(struct tty_struct *tty)
	147	{
	148	struct tty_struct *to = tty->link;
1da177e4 LT	149	int count;
	150
	151	/* We should get the line discipline lock for "tty->link" */
a352def2	152	if (!to \|\| !to->ldisc.ops->chars_in_buffer)
1da177e4 LT	153	return 0;
	154
	155	/* The ldisc must report 0 if no characters available to be read */
a352def2	156	count = to->ldisc.ops->chars_in_buffer(to);
1da177e4 LT	157
	158	if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
	159
	160	/* Master side driver ... if the other side's read buffer is less than
	161	* half full, return 0 to allow writers to proceed; otherwise return
	162	* the count. This leaves a comfortable margin to avoid overflow,
	163	* and still allows half a buffer's worth of typed-ahead commands.
	164	*/
	165	return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
	166	}
	167
	168	/* Set the lock flag on a pty */
	169	static int pty_set_lock(struct tty_struct tty, int __user arg)
	170	{
	171	int val;
	172	if (get_user(val,arg))
	173	return -EFAULT;
	174	if (val)
	175	set_bit(TTY_PTY_LOCK, &tty->flags);
	176	else
	177	clear_bit(TTY_PTY_LOCK, &tty->flags);
	178	return 0;
	179	}
	180
	181	static void pty_flush_buffer(struct tty_struct *tty)
	182	{
	183	struct tty_struct *to = tty->link;
04f378b1	184	unsigned long flags;
1da177e4 LT	185
	186	if (!to)
	187	return;
	188
a352def2 AC	189	if (to->ldisc.ops->flush_buffer)
a352def2 AC	190	to->ldisc.ops->flush_buffer(to);
1da177e4 LT	191
1da177e4 LT	192	if (to->packet) {
04f378b1	193	spin_lock_irqsave(&tty->ctrl_lock, flags);
1da177e4 LT	194	tty->ctrl_status \|= TIOCPKT_FLUSHWRITE;
1da177e4 LT	195	wake_up_interruptible(&to->read_wait);
04f378b1	196	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1da177e4 LT	197	}
	198	}
	199
	200	static int pty_open(struct tty_struct tty, struct file filp)
	201	{
	202	int retval = -ENODEV;
	203
	204	if (!tty \|\| !tty->link)
	205	goto out;
	206
	207	retval = -EIO;
	208	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
	209	goto out;
	210	if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
	211	goto out;
	212	if (tty->link->count != 1)
	213	goto out;
	214
	215	clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	216	set_bit(TTY_THROTTLED, &tty->flags);
	217	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	218	retval = 0;
	219	out:
	220	return retval;
	221	}
	222
606d099c	223	static void pty_set_termios(struct tty_struct tty, struct ktermios old_termios)
1da177e4 LT	224	{
	225	tty->termios->c_cflag &= ~(CSIZE \| PARENB);
	226	tty->termios->c_cflag \|= (CS8 \| CREAD);
	227	}
	228
b68e31d0	229	static const struct tty_operations pty_ops = {
1da177e4 LT	230	.open = pty_open,
	231	.close = pty_close,
	232	.write = pty_write,
	233	.write_room = pty_write_room,
	234	.flush_buffer = pty_flush_buffer,
	235	.chars_in_buffer = pty_chars_in_buffer,
	236	.unthrottle = pty_unthrottle,
	237	.set_termios = pty_set_termios,
	238	};
	239
	240	/* Traditional BSD devices */
	241	#ifdef CONFIG_LEGACY_PTYS
	242	static struct tty_driver pty_driver, pty_slave_driver;
	243
	244	static int pty_bsd_ioctl(struct tty_struct tty, struct file file,
	245	unsigned int cmd, unsigned long arg)
	246	{
	247	switch (cmd) {
	248	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
	249	return pty_set_lock(tty, (int __user *) arg);
	250	}
	251	return -ENOIOCTLCMD;
	252	}
	253
dc8c8587 KS	254	static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
	255	module_param(legacy_count, int, 0);
	256
3e8e88ca AC	257	static const struct tty_operations pty_ops_bsd = {
	258	.open = pty_open,
	259	.close = pty_close,
	260	.write = pty_write,
	261	.write_room = pty_write_room,
	262	.flush_buffer = pty_flush_buffer,
	263	.chars_in_buffer = pty_chars_in_buffer,
	264	.unthrottle = pty_unthrottle,
	265	.set_termios = pty_set_termios,
	266	.ioctl = pty_bsd_ioctl,
	267	};
	268
1da177e4 LT	269	static void __init legacy_pty_init(void)
1da177e4 LT	270	{
dc8c8587 KS	271	if (legacy_count <= 0)
dc8c8587 KS	272	return;
1da177e4	273
dc8c8587	274	pty_driver = alloc_tty_driver(legacy_count);
1da177e4 LT	275	if (!pty_driver)
	276	panic("Couldn't allocate pty driver");
	277
dc8c8587	278	pty_slave_driver = alloc_tty_driver(legacy_count);
1da177e4 LT	279	if (!pty_slave_driver)
	280	panic("Couldn't allocate pty slave driver");
	281
	282	pty_driver->owner = THIS_MODULE;
	283	pty_driver->driver_name = "pty_master";
	284	pty_driver->name = "pty";
1da177e4 LT	285	pty_driver->major = PTY_MASTER_MAJOR;
	286	pty_driver->minor_start = 0;
	287	pty_driver->type = TTY_DRIVER_TYPE_PTY;
	288	pty_driver->subtype = PTY_TYPE_MASTER;
	289	pty_driver->init_termios = tty_std_termios;
	290	pty_driver->init_termios.c_iflag = 0;
	291	pty_driver->init_termios.c_oflag = 0;
	292	pty_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	293	pty_driver->init_termios.c_lflag = 0;
606d099c AC	294	pty_driver->init_termios.c_ispeed = 38400;
606d099c AC	295	pty_driver->init_termios.c_ospeed = 38400;
1da177e4 LT	296	pty_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW;
	297	pty_driver->other = pty_slave_driver;
	298	tty_set_operations(pty_driver, &pty_ops);
1da177e4 LT	299
	300	pty_slave_driver->owner = THIS_MODULE;
	301	pty_slave_driver->driver_name = "pty_slave";
	302	pty_slave_driver->name = "ttyp";
1da177e4 LT	303	pty_slave_driver->major = PTY_SLAVE_MAJOR;
	304	pty_slave_driver->minor_start = 0;
	305	pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
	306	pty_slave_driver->subtype = PTY_TYPE_SLAVE;
	307	pty_slave_driver->init_termios = tty_std_termios;
	308	pty_slave_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
606d099c AC	309	pty_slave_driver->init_termios.c_ispeed = 38400;
606d099c AC	310	pty_slave_driver->init_termios.c_ospeed = 38400;
1da177e4 LT	311	pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS \|
	312	TTY_DRIVER_REAL_RAW;
	313	pty_slave_driver->other = pty_driver;
	314	tty_set_operations(pty_slave_driver, &pty_ops);
	315
	316	if (tty_register_driver(pty_driver))
	317	panic("Couldn't register pty driver");
	318	if (tty_register_driver(pty_slave_driver))
	319	panic("Couldn't register pty slave driver");
	320	}
	321	#else
	322	static inline void legacy_pty_init(void) { }
	323	#endif
	324
	325	/* Unix98 devices */
	326	#ifdef CONFIG_UNIX98_PTYS
	327	/*
	328	* sysctl support for setting limits on the number of Unix98 ptys allocated.
	329	* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
	330	*/
	331	int pty_limit = NR_UNIX98_PTY_DEFAULT;
	332	static int pty_limit_min = 0;
	333	static int pty_limit_max = NR_UNIX98_PTY_MAX;
	334
35834ca1	335	static struct ctl_table pty_table[] = {
1da177e4 LT	336	{
	337	.ctl_name = PTY_MAX,
	338	.procname = "max",
	339	.maxlen = sizeof(int),
	340	.mode = 0644,
	341	.data = &pty_limit,
	342	.proc_handler = &proc_dointvec_minmax,
	343	.strategy = &sysctl_intvec,
	344	.extra1 = &pty_limit_min,
	345	.extra2 = &pty_limit_max,
	346	}, {
	347	.ctl_name = PTY_NR,
	348	.procname = "nr",
	349	.maxlen = sizeof(int),
	350	.mode = 0444,
	351	.proc_handler = &proc_dointvec,
	352	}, {
	353	.ctl_name = 0
	354	}
	355	};
	356
35834ca1 EB	357	static struct ctl_table pty_kern_table[] = {
	358	{
	359	.ctl_name = KERN_PTY,
	360	.procname = "pty",
	361	.mode = 0555,
	362	.child = pty_table,
	363	},
	364	{}
	365	};
	366
	367	static struct ctl_table pty_root_table[] = {
	368	{
	369	.ctl_name = CTL_KERN,
	370	.procname = "kernel",
	371	.mode = 0555,
	372	.child = pty_kern_table,
	373	},
	374	{}
	375	};
	376
	377
1da177e4 LT	378	static int pty_unix98_ioctl(struct tty_struct tty, struct file file,
	379	unsigned int cmd, unsigned long arg)
	380	{
	381	switch (cmd) {
	382	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
	383	return pty_set_lock(tty, (int __user *)arg);
	384	case TIOCGPTN: /* Get PT Number */
	385	return put_user(tty->index, (unsigned int __user *)arg);
	386	}
	387
	388	return -ENOIOCTLCMD;
	389	}
	390
3e8e88ca AC	391	static const struct tty_operations pty_unix98_ops = {
	392	.open = pty_open,
	393	.close = pty_close,
	394	.write = pty_write,
	395	.write_room = pty_write_room,
	396	.flush_buffer = pty_flush_buffer,
	397	.chars_in_buffer = pty_chars_in_buffer,
	398	.unthrottle = pty_unthrottle,
	399	.set_termios = pty_set_termios,
	400	.ioctl = pty_unix98_ioctl
	401	};
	402
	403
1da177e4 LT	404	static void __init unix98_pty_init(void)
1da177e4 LT	405	{
1da177e4 LT	406	ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	407	if (!ptm_driver)
	408	panic("Couldn't allocate Unix98 ptm driver");
	409	pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
	410	if (!pts_driver)
	411	panic("Couldn't allocate Unix98 pts driver");
	412
	413	ptm_driver->owner = THIS_MODULE;
	414	ptm_driver->driver_name = "pty_master";
	415	ptm_driver->name = "ptm";
	416	ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
	417	ptm_driver->minor_start = 0;
	418	ptm_driver->type = TTY_DRIVER_TYPE_PTY;
	419	ptm_driver->subtype = PTY_TYPE_MASTER;
	420	ptm_driver->init_termios = tty_std_termios;
	421	ptm_driver->init_termios.c_iflag = 0;
	422	ptm_driver->init_termios.c_oflag = 0;
	423	ptm_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
	424	ptm_driver->init_termios.c_lflag = 0;
606d099c AC	425	ptm_driver->init_termios.c_ispeed = 38400;
606d099c AC	426	ptm_driver->init_termios.c_ospeed = 38400;
1da177e4	427	ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW \|
331b8319	428	TTY_DRIVER_DYNAMIC_DEV \| TTY_DRIVER_DEVPTS_MEM;
1da177e4	429	ptm_driver->other = pts_driver;
3e8e88ca	430	tty_set_operations(ptm_driver, &pty_unix98_ops);
1da177e4 LT	431
	432	pts_driver->owner = THIS_MODULE;
	433	pts_driver->driver_name = "pty_slave";
	434	pts_driver->name = "pts";
	435	pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
	436	pts_driver->minor_start = 0;
	437	pts_driver->type = TTY_DRIVER_TYPE_PTY;
	438	pts_driver->subtype = PTY_TYPE_SLAVE;
	439	pts_driver->init_termios = tty_std_termios;
	440	pts_driver->init_termios.c_cflag = B38400 \| CS8 \| CREAD;
606d099c AC	441	pts_driver->init_termios.c_ispeed = 38400;
606d099c AC	442	pts_driver->init_termios.c_ospeed = 38400;
1da177e4	443	pts_driver->flags = TTY_DRIVER_RESET_TERMIOS \| TTY_DRIVER_REAL_RAW \|
331b8319	444	TTY_DRIVER_DYNAMIC_DEV \| TTY_DRIVER_DEVPTS_MEM;
1da177e4 LT	445	pts_driver->other = ptm_driver;
	446	tty_set_operations(pts_driver, &pty_ops);
	447
	448	if (tty_register_driver(ptm_driver))
	449	panic("Couldn't register Unix98 ptm driver");
	450	if (tty_register_driver(pts_driver))
	451	panic("Couldn't register Unix98 pts driver");
	452
	453	pty_table[1].data = &ptm_driver->refcount;
35834ca1	454	register_sysctl_table(pty_root_table);
1da177e4 LT	455	}
	456	#else
	457	static inline void unix98_pty_init(void) { }
	458	#endif
	459
	460	static int __init pty_init(void)
	461	{
	462	legacy_pty_init();
	463	unix98_pty_init();
	464	return 0;
	465	}
	466	module_init(pty_init);