tty_io.c 78.2 KB
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/*
 *  linux/drivers/char/tty_io.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
 * or rs-channels. It also implements echoing, cooked mode etc.
 *
 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
 *
 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
 * tty_struct and tty_queue structures.  Previously there was an array
 * of 256 tty_struct's which was statically allocated, and the
 * tty_queue structures were allocated at boot time.  Both are now
 * dynamically allocated only when the tty is open.
 *
 * Also restructured routines so that there is more of a separation
 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
 * the low-level tty routines (serial.c, pty.c, console.c).  This
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 * makes for cleaner and more compact code.  -TYT, 9/17/92
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 *
 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
 * which can be dynamically activated and de-activated by the line
 * discipline handling modules (like SLIP).
 *
 * NOTE: pay no attention to the line discipline code (yet); its
 * interface is still subject to change in this version...
 * -- TYT, 1/31/92
 *
 * Added functionality to the OPOST tty handling.  No delays, but all
 * other bits should be there.
 *	-- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
 *
 * Rewrote canonical mode and added more termios flags.
 * 	-- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
 *
 * Reorganized FASYNC support so mouse code can share it.
 *	-- ctm@ardi.com, 9Sep95
 *
 * New TIOCLINUX variants added.
 *	-- mj@k332.feld.cvut.cz, 19-Nov-95
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 *
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 * Restrict vt switching via ioctl()
 *      -- grif@cs.ucr.edu, 5-Dec-95
 *
 * Move console and virtual terminal code to more appropriate files,
 * implement CONFIG_VT and generalize console device interface.
 *	-- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
 *
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 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
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 *	-- Bill Hawes <whawes@star.net>, June 97
 *
 * Added devfs support.
 *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
 *
 * Added support for a Unix98-style ptmx device.
 *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
 *
 * Reduced memory usage for older ARM systems
 *      -- Russell King <rmk@arm.linux.org.uk>
 *
 * Move do_SAK() into process context.  Less stack use in devfs functions.
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 * alloc_tty_struct() always uses kmalloc()
 *			 -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
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 */

#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/devpts_fs.h>
#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/console.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/kd.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/bitops.h>
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#include <linux/delay.h>
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#include <linux/seq_file.h>
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#include <linux/uaccess.h>
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#include <asm/system.h>

#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>

#include <linux/kmod.h>
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#include <linux/nsproxy.h>
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#undef TTY_DEBUG_HANGUP

#define TTY_PARANOIA_CHECK 1
#define CHECK_TTY_COUNT 1

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struct ktermios tty_std_termios = {	/* for the benefit of tty drivers  */
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	.c_iflag = ICRNL | IXON,
	.c_oflag = OPOST | ONLCR,
	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
	.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
		   ECHOCTL | ECHOKE | IEXTEN,
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	.c_cc = INIT_C_CC,
	.c_ispeed = 38400,
	.c_ospeed = 38400
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};

EXPORT_SYMBOL(tty_std_termios);

/* This list gets poked at by procfs and various bits of boot up code. This
   could do with some rationalisation such as pulling the tty proc function
   into this file */
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LIST_HEAD(tty_drivers);			/* linked list of tty drivers */

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/* Mutex to protect creating and releasing a tty. This is shared with
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   vt.c for deeply disgusting hack reasons */
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DEFINE_MUTEX(tty_mutex);
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EXPORT_SYMBOL(tty_mutex);
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static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
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ssize_t redirected_tty_write(struct file *, const char __user *,
							size_t, loff_t *);
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static unsigned int tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
static int tty_release(struct inode *, struct file *);
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long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
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#ifdef CONFIG_COMPAT
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static long tty_compat_ioctl(struct file *file, unsigned int cmd,
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				unsigned long arg);
#else
#define tty_compat_ioctl NULL
#endif
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static int tty_fasync(int fd, struct file *filp, int on);
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static void release_tty(struct tty_struct *tty, int idx);
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static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
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static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
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/**
 *	alloc_tty_struct	-	allocate a tty object
 *
 *	Return a new empty tty structure. The data fields have not
 *	been initialized in any way but has been zeroed
 *
 *	Locking: none
 */
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struct tty_struct *alloc_tty_struct(void)
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{
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	return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
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}

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/**
 *	free_tty_struct		-	free a disused tty
 *	@tty: tty struct to free
 *
 *	Free the write buffers, tty queue and tty memory itself.
 *
 *	Locking: none. Must be called after tty is definitely unused
 */

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void free_tty_struct(struct tty_struct *tty)
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{
	kfree(tty->write_buf);
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	tty_buffer_free_all(tty);
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	kfree(tty);
}

#define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)

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/**
 *	tty_name	-	return tty naming
 *	@tty: tty structure
 *	@buf: buffer for output
 *
 *	Convert a tty structure into a name. The name reflects the kernel
 *	naming policy and if udev is in use may not reflect user space
 *
 *	Locking: none
 */

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char *tty_name(struct tty_struct *tty, char *buf)
{
	if (!tty) /* Hmm.  NULL pointer.  That's fun. */
		strcpy(buf, "NULL tty");
	else
		strcpy(buf, tty->name);
	return buf;
}

EXPORT_SYMBOL(tty_name);

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int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
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			      const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
	if (!tty) {
		printk(KERN_WARNING
			"null TTY for (%d:%d) in %s\n",
			imajor(inode), iminor(inode), routine);
		return 1;
	}
	if (tty->magic != TTY_MAGIC) {
		printk(KERN_WARNING
			"bad magic number for tty struct (%d:%d) in %s\n",
			imajor(inode), iminor(inode), routine);
		return 1;
	}
#endif
	return 0;
}

static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
	struct list_head *p;
	int count = 0;
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	file_list_lock();
	list_for_each(p, &tty->tty_files) {
		count++;
	}
	file_list_unlock();
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_SLAVE &&
	    tty->link && tty->link->count)
		count++;
	if (tty->count != count) {
		printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
				    "!= #fd's(%d) in %s\n",
		       tty->name, tty->count, count, routine);
		return count;
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	}
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#endif
	return 0;
}

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/**
 *	get_tty_driver		-	find device of a tty
 *	@dev_t: device identifier
 *	@index: returns the index of the tty
 *
 *	This routine returns a tty driver structure, given a device number
 *	and also passes back the index number.
 *
 *	Locking: caller must hold tty_mutex
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 */
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static struct tty_driver *get_tty_driver(dev_t device, int *index)
{
	struct tty_driver *p;

	list_for_each_entry(p, &tty_drivers, tty_drivers) {
		dev_t base = MKDEV(p->major, p->minor_start);
		if (device < base || device >= base + p->num)
			continue;
		*index = device - base;
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		return tty_driver_kref_get(p);
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	}
	return NULL;
}

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#ifdef CONFIG_CONSOLE_POLL

/**
 *	tty_find_polling_driver	-	find device of a polled tty
 *	@name: name string to match
 *	@line: pointer to resulting tty line nr
 *
 *	This routine returns a tty driver structure, given a name
 *	and the condition that the tty driver is capable of polled
 *	operation.
 */
struct tty_driver *tty_find_polling_driver(char *name, int *line)
{
	struct tty_driver *p, *res = NULL;
	int tty_line = 0;
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	int len;
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	char *str;

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	for (str = name; *str; str++)
		if ((*str >= '0' && *str <= '9') || *str == ',')
			break;
	if (!*str)
		return NULL;

	len = str - name;
	tty_line = simple_strtoul(str, &str, 10);

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	mutex_lock(&tty_mutex);
	/* Search through the tty devices to look for a match */
	list_for_each_entry(p, &tty_drivers, tty_drivers) {
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		if (strncmp(name, p->name, len) != 0)
			continue;
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		if (*str == ',')
			str++;
		if (*str == '\0')
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			str = NULL;
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		if (tty_line >= 0 && tty_line <= p->num && p->ops &&
		    p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
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			res = tty_driver_kref_get(p);
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			*line = tty_line;
			break;
		}
	}
	mutex_unlock(&tty_mutex);

	return res;
}
EXPORT_SYMBOL_GPL(tty_find_polling_driver);
#endif

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/**
 *	tty_check_change	-	check for POSIX terminal changes
 *	@tty: tty to check
 *
 *	If we try to write to, or set the state of, a terminal and we're
 *	not in the foreground, send a SIGTTOU.  If the signal is blocked or
 *	ignored, go ahead and perform the operation.  (POSIX 7.2)
 *
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 *	Locking: ctrl_lock
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 */
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int tty_check_change(struct tty_struct *tty)
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{
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	unsigned long flags;
	int ret = 0;

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	if (current->signal->tty != tty)
		return 0;
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	spin_lock_irqsave(&tty->ctrl_lock, flags);

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	if (!tty->pgrp) {
		printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
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		goto out_unlock;
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	}
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	if (task_pgrp(current) == tty->pgrp)
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		goto out_unlock;
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
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	if (is_ignored(SIGTTOU))
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		goto out;
	if (is_current_pgrp_orphaned()) {
		ret = -EIO;
		goto out;
	}
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	kill_pgrp(task_pgrp(current), SIGTTOU, 1);
	set_thread_flag(TIF_SIGPENDING);
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	ret = -ERESTARTSYS;
out:
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	return ret;
out_unlock:
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	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	return ret;
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}

EXPORT_SYMBOL(tty_check_change);

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static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
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				size_t count, loff_t *ppos)
{
	return 0;
}

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static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
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				 size_t count, loff_t *ppos)
{
	return -EIO;
}

/* No kernel lock held - none needed ;) */
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static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
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{
	return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
}

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static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
		unsigned long arg)
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{
	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}

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static long hung_up_tty_compat_ioctl(struct file *file,
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				     unsigned int cmd, unsigned long arg)
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{
	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}

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static const struct file_operations tty_fops = {
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	.llseek		= no_llseek,
	.read		= tty_read,
	.write		= tty_write,
	.poll		= tty_poll,
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	.unlocked_ioctl	= tty_ioctl,
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	.compat_ioctl	= tty_compat_ioctl,
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	.open		= tty_open,
	.release	= tty_release,
	.fasync		= tty_fasync,
};

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static const struct file_operations console_fops = {
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	.llseek		= no_llseek,
	.read		= tty_read,
	.write		= redirected_tty_write,
	.poll		= tty_poll,
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	.unlocked_ioctl	= tty_ioctl,
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	.compat_ioctl	= tty_compat_ioctl,
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	.open		= tty_open,
	.release	= tty_release,
	.fasync		= tty_fasync,
};

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static const struct file_operations hung_up_tty_fops = {
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	.llseek		= no_llseek,
	.read		= hung_up_tty_read,
	.write		= hung_up_tty_write,
	.poll		= hung_up_tty_poll,
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	.unlocked_ioctl	= hung_up_tty_ioctl,
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	.compat_ioctl	= hung_up_tty_compat_ioctl,
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	.release	= tty_release,
};

static DEFINE_SPINLOCK(redirect_lock);
static struct file *redirect;

/**
 *	tty_wakeup	-	request more data
 *	@tty: terminal
 *
 *	Internal and external helper for wakeups of tty. This function
 *	informs the line discipline if present that the driver is ready
 *	to receive more output data.
 */
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void tty_wakeup(struct tty_struct *tty)
{
	struct tty_ldisc *ld;
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	if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
		ld = tty_ldisc_ref(tty);
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		if (ld) {
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			if (ld->ops->write_wakeup)
				ld->ops->write_wakeup(tty);
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			tty_ldisc_deref(ld);
		}
	}
	wake_up_interruptible(&tty->write_wait);
}

EXPORT_SYMBOL_GPL(tty_wakeup);

/**
 *	tty_ldisc_flush	-	flush line discipline queue
 *	@tty: tty
 *
 *	Flush the line discipline queue (if any) for this tty. If there
 *	is no line discipline active this is a no-op.
 */
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void tty_ldisc_flush(struct tty_struct *tty)
{
	struct tty_ldisc *ld = tty_ldisc_ref(tty);
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	if (ld) {
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		if (ld->ops->flush_buffer)
			ld->ops->flush_buffer(tty);
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		tty_ldisc_deref(ld);
	}
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	tty_buffer_flush(tty);
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}

EXPORT_SYMBOL_GPL(tty_ldisc_flush);
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/**
 *	tty_reset_termios	-	reset terminal state
 *	@tty: tty to reset
 *
 *	Restore a terminal to the driver default state
 */

static void tty_reset_termios(struct tty_struct *tty)
{
	mutex_lock(&tty->termios_mutex);
	*tty->termios = tty->driver->init_termios;
	tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
	tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
	mutex_unlock(&tty->termios_mutex);
}
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/**
 *	do_tty_hangup		-	actual handler for hangup events
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 *	@work: tty device
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 *
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 *	This can be called by the "eventd" kernel thread.  That is process
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 *	synchronous but doesn't hold any locks, so we need to make sure we
 *	have the appropriate locks for what we're doing.
 *
 *	The hangup event clears any pending redirections onto the hung up
 *	device. It ensures future writes will error and it does the needed
 *	line discipline hangup and signal delivery. The tty object itself
 *	remains intact.
 *
 *	Locking:
 *		BKL
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 *		  redirect lock for undoing redirection
 *		  file list lock for manipulating list of ttys
 *		  tty_ldisc_lock from called functions
 *		  termios_mutex resetting termios data
 *		  tasklist_lock to walk task list for hangup event
 *		    ->siglock to protect ->signal/->sighand
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 */
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static void do_tty_hangup(struct work_struct *work)
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{
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	struct tty_struct *tty =
		container_of(work, struct tty_struct, hangup_work);
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	struct file *cons_filp = NULL;
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	struct file *filp, *f = NULL;
	struct task_struct *p;
	struct tty_ldisc *ld;
	int    closecount = 0, n;
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	unsigned long flags;
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	int refs = 0;
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	if (!tty)
		return;

	/* inuse_filps is protected by the single kernel lock */
	lock_kernel();

	spin_lock(&redirect_lock);
	if (redirect && redirect->private_data == tty) {
		f = redirect;
		redirect = NULL;
	}
	spin_unlock(&redirect_lock);
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	check_tty_count(tty, "do_tty_hangup");
	file_list_lock();
	/* This breaks for file handles being sent over AF_UNIX sockets ? */
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	list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
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		if (filp->f_op->write == redirected_tty_write)
			cons_filp = filp;
		if (filp->f_op->write != tty_write)
			continue;
		closecount++;
		tty_fasync(-1, filp, 0);	/* can't block */
		filp->f_op = &hung_up_tty_fops;
	}
	file_list_unlock();
569 570 571 572 573
	/*
	 * FIXME! What are the locking issues here? This may me overdoing
	 * things... This question is especially important now that we've
	 * removed the irqlock.
	 */
L
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574
	ld = tty_ldisc_ref(tty);
575 576
	if (ld != NULL) {
		/* We may have no line discipline at this point */
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577 578
		if (ld->ops->flush_buffer)
			ld->ops->flush_buffer(tty);
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579
		tty_driver_flush_buffer(tty);
L
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580
		if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
A
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581 582 583 584
		    ld->ops->write_wakeup)
			ld->ops->write_wakeup(tty);
		if (ld->ops->hangup)
			ld->ops->hangup(tty);
L
Linus Torvalds 已提交
585
	}
586 587 588 589
	/*
	 * FIXME: Once we trust the LDISC code better we can wait here for
	 * ldisc completion and fix the driver call race
	 */
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	wake_up_interruptible(&tty->write_wait);
	wake_up_interruptible(&tty->read_wait);
	/*
	 * Shutdown the current line discipline, and reset it to
	 * N_TTY.
	 */
	if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
597
		tty_reset_termios(tty);
L
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	/* Defer ldisc switch */
	/* tty_deferred_ldisc_switch(N_TTY);
600

L
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601 602
	  This should get done automatically when the port closes and
	  tty_release is called */
603

L
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604
	read_lock(&tasklist_lock);
605 606
	if (tty->session) {
		do_each_pid_task(tty->session, PIDTYPE_SID, p) {
607
			spin_lock_irq(&p->sighand->siglock);
A
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608
			if (p->signal->tty == tty) {
L
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609
				p->signal->tty = NULL;
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610 611 612 613
				/* We defer the dereferences outside fo
				   the tasklist lock */
				refs++;
			}
614 615
			if (!p->signal->leader) {
				spin_unlock_irq(&p->sighand->siglock);
L
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616
				continue;
617 618 619
			}
			__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
			__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
620
			put_pid(p->signal->tty_old_pgrp);  /* A noop */
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			spin_lock_irqsave(&tty->ctrl_lock, flags);
622 623
			if (tty->pgrp)
				p->signal->tty_old_pgrp = get_pid(tty->pgrp);
A
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			spin_unlock_irqrestore(&tty->ctrl_lock, flags);
625
			spin_unlock_irq(&p->sighand->siglock);
626
		} while_each_pid_task(tty->session, PIDTYPE_SID, p);
L
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627 628 629
	}
	read_unlock(&tasklist_lock);

A
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630
	spin_lock_irqsave(&tty->ctrl_lock, flags);
L
Linus Torvalds 已提交
631
	tty->flags = 0;
632 633
	put_pid(tty->session);
	put_pid(tty->pgrp);
634 635
	tty->session = NULL;
	tty->pgrp = NULL;
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636
	tty->ctrl_status = 0;
A
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637 638
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

A
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639 640 641 642
	/* Account for the p->signal references we killed */
	while (refs--)
		tty_kref_put(tty);

L
Linus Torvalds 已提交
643
	/*
644 645 646 647
	 * If one of the devices matches a console pointer, we
	 * cannot just call hangup() because that will cause
	 * tty->count and state->count to go out of sync.
	 * So we just call close() the right number of times.
L
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	 */
	if (cons_filp) {
A
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650
		if (tty->ops->close)
L
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651
			for (n = 0; n < closecount; n++)
A
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652 653 654
				tty->ops->close(tty, cons_filp);
	} else if (tty->ops->hangup)
		(tty->ops->hangup)(tty);
655 656 657 658 659 660
	/*
	 * We don't want to have driver/ldisc interactions beyond
	 * the ones we did here. The driver layer expects no
	 * calls after ->hangup() from the ldisc side. However we
	 * can't yet guarantee all that.
	 */
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	set_bit(TTY_HUPPED, &tty->flags);
	if (ld) {
		tty_ldisc_enable(tty);
		tty_ldisc_deref(ld);
	}
	unlock_kernel();
	if (f)
		fput(f);
}

671 672 673 674 675 676 677 678
/**
 *	tty_hangup		-	trigger a hangup event
 *	@tty: tty to hangup
 *
 *	A carrier loss (virtual or otherwise) has occurred on this like
 *	schedule a hangup sequence to run after this event.
 */

679
void tty_hangup(struct tty_struct *tty)
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{
#ifdef TTY_DEBUG_HANGUP
	char	buf[64];
	printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
#endif
	schedule_work(&tty->hangup_work);
}

EXPORT_SYMBOL(tty_hangup);

690 691 692 693 694 695
/**
 *	tty_vhangup		-	process vhangup
 *	@tty: tty to hangup
 *
 *	The user has asked via system call for the terminal to be hung up.
 *	We do this synchronously so that when the syscall returns the process
696
 *	is complete. That guarantee is necessary for security reasons.
697 698
 */

699
void tty_vhangup(struct tty_struct *tty)
L
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{
#ifdef TTY_DEBUG_HANGUP
	char	buf[64];

	printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
#endif
706
	do_tty_hangup(&tty->hangup_work);
L
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707
}
708

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EXPORT_SYMBOL(tty_vhangup);

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711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727
/**
 *	tty_vhangup_self	-	process vhangup for own ctty
 *
 *	Perform a vhangup on the current controlling tty
 */

void tty_vhangup_self(void)
{
	struct tty_struct *tty;

	tty = get_current_tty();
	if (tty) {
		tty_vhangup(tty);
		tty_kref_put(tty);
	}
}

728 729 730 731 732 733 734 735
/**
 *	tty_hung_up_p		-	was tty hung up
 *	@filp: file pointer of tty
 *
 *	Return true if the tty has been subject to a vhangup or a carrier
 *	loss
 */

736
int tty_hung_up_p(struct file *filp)
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{
	return (filp->f_op == &hung_up_tty_fops);
}

EXPORT_SYMBOL(tty_hung_up_p);

743
static void session_clear_tty(struct pid *session)
744 745
{
	struct task_struct *p;
746
	do_each_pid_task(session, PIDTYPE_SID, p) {
747
		proc_clear_tty(p);
748
	} while_each_pid_task(session, PIDTYPE_SID, p);
749 750
}

751 752 753
/**
 *	disassociate_ctty	-	disconnect controlling tty
 *	@on_exit: true if exiting so need to "hang up" the session
L
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 *
755 756 757 758
 *	This function is typically called only by the session leader, when
 *	it wants to disassociate itself from its controlling tty.
 *
 *	It performs the following functions:
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 * 	(1)  Sends a SIGHUP and SIGCONT to the foreground process group
 * 	(2)  Clears the tty from being controlling the session
 * 	(3)  Clears the controlling tty for all processes in the
 * 		session group.
 *
764 765 766
 *	The argument on_exit is set to 1 if called when a process is
 *	exiting; it is 0 if called by the ioctl TIOCNOTTY.
 *
767
 *	Locking:
768
 *		BKL is taken for hysterical raisins
769 770 771 772
 *		  tty_mutex is taken to protect tty
 *		  ->siglock is taken to protect ->signal/->sighand
 *		  tasklist_lock is taken to walk process list for sessions
 *		    ->siglock is taken to protect ->signal/->sighand
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 */
774

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void disassociate_ctty(int on_exit)
{
	struct tty_struct *tty;
778
	struct pid *tty_pgrp = NULL;
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781
	tty = get_current_tty();
L
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782
	if (tty) {
783
		tty_pgrp = get_pid(tty->pgrp);
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784
		lock_kernel();
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		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
			tty_vhangup(tty);
A
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787
		unlock_kernel();
A
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788
		tty_kref_put(tty);
789
	} else if (on_exit) {
790
		struct pid *old_pgrp;
791 792
		spin_lock_irq(&current->sighand->siglock);
		old_pgrp = current->signal->tty_old_pgrp;
793
		current->signal->tty_old_pgrp = NULL;
794
		spin_unlock_irq(&current->sighand->siglock);
795
		if (old_pgrp) {
796 797 798
			kill_pgrp(old_pgrp, SIGHUP, on_exit);
			kill_pgrp(old_pgrp, SIGCONT, on_exit);
			put_pid(old_pgrp);
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		}
		return;
	}
802 803
	if (tty_pgrp) {
		kill_pgrp(tty_pgrp, SIGHUP, on_exit);
L
Linus Torvalds 已提交
804
		if (!on_exit)
805 806
			kill_pgrp(tty_pgrp, SIGCONT, on_exit);
		put_pid(tty_pgrp);
L
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	}

809
	spin_lock_irq(&current->sighand->siglock);
810
	put_pid(current->signal->tty_old_pgrp);
R
Randy Dunlap 已提交
811
	current->signal->tty_old_pgrp = NULL;
812 813 814 815
	spin_unlock_irq(&current->sighand->siglock);

	tty = get_current_tty();
	if (tty) {
A
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816 817
		unsigned long flags;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
818 819 820 821
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = NULL;
		tty->pgrp = NULL;
A
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822
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
A
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823
		tty_kref_put(tty);
824 825 826 827 828 829
	} else {
#ifdef TTY_DEBUG_HANGUP
		printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
		       " = NULL", tty);
#endif
	}
L
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830 831 832

	/* Now clear signal->tty under the lock */
	read_lock(&tasklist_lock);
833
	session_clear_tty(task_session(current));
L
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834 835 836
	read_unlock(&tasklist_lock);
}

837 838 839 840 841 842 843
/**
 *
 *	no_tty	- Ensure the current process does not have a controlling tty
 */
void no_tty(void)
{
	struct task_struct *tsk = current;
A
Alan Cox 已提交
844
	lock_kernel();
845 846
	if (tsk->signal->leader)
		disassociate_ctty(0);
A
Alan Cox 已提交
847
	unlock_kernel();
848 849 850
	proc_clear_tty(tsk);
}

851 852

/**
853
 *	stop_tty	-	propagate flow control
854 855 856
 *	@tty: tty to stop
 *
 *	Perform flow control to the driver. For PTY/TTY pairs we
857
 *	must also propagate the TIOCKPKT status. May be called
858 859 860 861 862 863 864 865 866
 *	on an already stopped device and will not re-call the driver
 *	method.
 *
 *	This functionality is used by both the line disciplines for
 *	halting incoming flow and by the driver. It may therefore be
 *	called from any context, may be under the tty atomic_write_lock
 *	but not always.
 *
 *	Locking:
A
Alan Cox 已提交
867
 *		Uses the tty control lock internally
868 869
 */

L
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870 871
void stop_tty(struct tty_struct *tty)
{
A
Alan Cox 已提交
872 873 874 875
	unsigned long flags;
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	if (tty->stopped) {
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
L
Linus Torvalds 已提交
876
		return;
A
Alan Cox 已提交
877
	}
L
Linus Torvalds 已提交
878 879 880 881 882 883
	tty->stopped = 1;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_START;
		tty->ctrl_status |= TIOCPKT_STOP;
		wake_up_interruptible(&tty->link->read_wait);
	}
A
Alan Cox 已提交
884
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
A
Alan Cox 已提交
885 886
	if (tty->ops->stop)
		(tty->ops->stop)(tty);
L
Linus Torvalds 已提交
887 888 889 890
}

EXPORT_SYMBOL(stop_tty);

891
/**
892
 *	start_tty	-	propagate flow control
893 894 895
 *	@tty: tty to start
 *
 *	Start a tty that has been stopped if at all possible. Perform
896
 *	any necessary wakeups and propagate the TIOCPKT status. If this
897 898 899 900
 *	is the tty was previous stopped and is being started then the
 *	driver start method is invoked and the line discipline woken.
 *
 *	Locking:
A
Alan Cox 已提交
901
 *		ctrl_lock
902 903
 */

L
Linus Torvalds 已提交
904 905
void start_tty(struct tty_struct *tty)
{
A
Alan Cox 已提交
906 907 908 909
	unsigned long flags;
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	if (!tty->stopped || tty->flow_stopped) {
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
L
Linus Torvalds 已提交
910
		return;
A
Alan Cox 已提交
911
	}
L
Linus Torvalds 已提交
912 913 914 915 916 917
	tty->stopped = 0;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_STOP;
		tty->ctrl_status |= TIOCPKT_START;
		wake_up_interruptible(&tty->link->read_wait);
	}
A
Alan Cox 已提交
918
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
A
Alan Cox 已提交
919 920
	if (tty->ops->start)
		(tty->ops->start)(tty);
L
Linus Torvalds 已提交
921 922 923 924 925 926
	/* If we have a running line discipline it may need kicking */
	tty_wakeup(tty);
}

EXPORT_SYMBOL(start_tty);

927 928 929 930 931 932 933 934 935 936 937
/**
 *	tty_read	-	read method for tty device files
 *	@file: pointer to tty file
 *	@buf: user buffer
 *	@count: size of user buffer
 *	@ppos: unused
 *
 *	Perform the read system call function on this terminal device. Checks
 *	for hung up devices before calling the line discipline method.
 *
 *	Locking:
A
Alan Cox 已提交
938 939
 *		Locks the line discipline internally while needed. Multiple
 *	read calls may be outstanding in parallel.
940 941
 */

942
static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
L
Linus Torvalds 已提交
943 944 945
			loff_t *ppos)
{
	int i;
946
	struct tty_struct *tty;
L
Linus Torvalds 已提交
947 948 949 950
	struct inode *inode;
	struct tty_ldisc *ld;

	tty = (struct tty_struct *)file->private_data;
951
	inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
952 953 954 955 956 957 958 959
	if (tty_paranoia_check(tty, inode, "tty_read"))
		return -EIO;
	if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
		return -EIO;

	/* We want to wait for the line discipline to sort out in this
	   situation */
	ld = tty_ldisc_ref_wait(tty);
A
Alan Cox 已提交
960 961
	if (ld->ops->read)
		i = (ld->ops->read)(tty, file, buf, count);
L
Linus Torvalds 已提交
962 963 964 965 966 967 968 969
	else
		i = -EIO;
	tty_ldisc_deref(ld);
	if (i > 0)
		inode->i_atime = current_fs_time(inode->i_sb);
	return i;
}

970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986
void tty_write_unlock(struct tty_struct *tty)
{
	mutex_unlock(&tty->atomic_write_lock);
	wake_up_interruptible(&tty->write_wait);
}

int tty_write_lock(struct tty_struct *tty, int ndelay)
{
	if (!mutex_trylock(&tty->atomic_write_lock)) {
		if (ndelay)
			return -EAGAIN;
		if (mutex_lock_interruptible(&tty->atomic_write_lock))
			return -ERESTARTSYS;
	}
	return 0;
}

L
Linus Torvalds 已提交
987 988 989 990 991 992 993 994 995 996 997
/*
 * Split writes up in sane blocksizes to avoid
 * denial-of-service type attacks
 */
static inline ssize_t do_tty_write(
	ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
	struct tty_struct *tty,
	struct file *file,
	const char __user *buf,
	size_t count)
{
998
	ssize_t ret, written = 0;
L
Linus Torvalds 已提交
999
	unsigned int chunk;
1000

1001 1002 1003
	ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
	if (ret < 0)
		return ret;
L
Linus Torvalds 已提交
1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016

	/*
	 * We chunk up writes into a temporary buffer. This
	 * simplifies low-level drivers immensely, since they
	 * don't have locking issues and user mode accesses.
	 *
	 * But if TTY_NO_WRITE_SPLIT is set, we should use a
	 * big chunk-size..
	 *
	 * The default chunk-size is 2kB, because the NTTY
	 * layer has problems with bigger chunks. It will
	 * claim to be able to handle more characters than
	 * it actually does.
1017 1018 1019
	 *
	 * FIXME: This can probably go away now except that 64K chunks
	 * are too likely to fail unless switched to vmalloc...
L
Linus Torvalds 已提交
1020 1021 1022 1023 1024 1025 1026
	 */
	chunk = 2048;
	if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
		chunk = 65536;
	if (count < chunk)
		chunk = count;

I
Ingo Molnar 已提交
1027
	/* write_buf/write_cnt is protected by the atomic_write_lock mutex */
L
Linus Torvalds 已提交
1028
	if (tty->write_cnt < chunk) {
J
Jason Wessel 已提交
1029
		unsigned char *buf_chunk;
L
Linus Torvalds 已提交
1030 1031 1032 1033

		if (chunk < 1024)
			chunk = 1024;

J
Jason Wessel 已提交
1034 1035
		buf_chunk = kmalloc(chunk, GFP_KERNEL);
		if (!buf_chunk) {
1036 1037
			ret = -ENOMEM;
			goto out;
L
Linus Torvalds 已提交
1038 1039 1040
		}
		kfree(tty->write_buf);
		tty->write_cnt = chunk;
J
Jason Wessel 已提交
1041
		tty->write_buf = buf_chunk;
L
Linus Torvalds 已提交
1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
	}

	/* Do the write .. */
	for (;;) {
		size_t size = count;
		if (size > chunk)
			size = chunk;
		ret = -EFAULT;
		if (copy_from_user(tty->write_buf, buf, size))
			break;
		ret = write(tty, file, tty->write_buf, size);
		if (ret <= 0)
			break;
		written += ret;
		buf += ret;
		count -= ret;
		if (!count)
			break;
		ret = -ERESTARTSYS;
		if (signal_pending(current))
			break;
		cond_resched();
	}
	if (written) {
1066
		struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1067 1068 1069
		inode->i_mtime = current_fs_time(inode->i_sb);
		ret = written;
	}
1070 1071
out:
	tty_write_unlock(tty);
L
Linus Torvalds 已提交
1072 1073 1074
	return ret;
}

1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
/**
 * tty_write_message - write a message to a certain tty, not just the console.
 * @tty: the destination tty_struct
 * @msg: the message to write
 *
 * This is used for messages that need to be redirected to a specific tty.
 * We don't put it into the syslog queue right now maybe in the future if
 * really needed.
 *
 * We must still hold the BKL and test the CLOSING flag for the moment.
 */

void tty_write_message(struct tty_struct *tty, char *msg)
{
	lock_kernel();
	if (tty) {
		mutex_lock(&tty->atomic_write_lock);
		if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
			tty->ops->write(tty, msg, strlen(msg));
		tty_write_unlock(tty);
	}
	unlock_kernel();
	return;
}

L
Linus Torvalds 已提交
1100

1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118
/**
 *	tty_write		-	write method for tty device file
 *	@file: tty file pointer
 *	@buf: user data to write
 *	@count: bytes to write
 *	@ppos: unused
 *
 *	Write data to a tty device via the line discipline.
 *
 *	Locking:
 *		Locks the line discipline as required
 *		Writes to the tty driver are serialized by the atomic_write_lock
 *	and are then processed in chunks to the device. The line discipline
 *	write method will not be involked in parallel for each device
 *		The line discipline write method is called under the big
 *	kernel lock for historical reasons. New code should not rely on this.
 */

1119 1120
static ssize_t tty_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
L
Linus Torvalds 已提交
1121
{
1122
	struct tty_struct *tty;
1123
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1124 1125
	ssize_t ret;
	struct tty_ldisc *ld;
1126

L
Linus Torvalds 已提交
1127 1128 1129
	tty = (struct tty_struct *)file->private_data;
	if (tty_paranoia_check(tty, inode, "tty_write"))
		return -EIO;
A
Alan Cox 已提交
1130
	if (!tty || !tty->ops->write ||
1131 1132
		(test_bit(TTY_IO_ERROR, &tty->flags)))
			return -EIO;
A
Alan Cox 已提交
1133 1134 1135 1136
	/* Short term debug to catch buggy drivers */
	if (tty->ops->write_room == NULL)
		printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
			tty->driver->name);
1137
	ld = tty_ldisc_ref_wait(tty);
A
Alan Cox 已提交
1138
	if (!ld->ops->write)
L
Linus Torvalds 已提交
1139 1140
		ret = -EIO;
	else
A
Alan Cox 已提交
1141
		ret = do_tty_write(ld->ops->write, tty, file, buf, count);
L
Linus Torvalds 已提交
1142 1143 1144 1145
	tty_ldisc_deref(ld);
	return ret;
}

1146 1147
ssize_t redirected_tty_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
L
Linus Torvalds 已提交
1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168
{
	struct file *p = NULL;

	spin_lock(&redirect_lock);
	if (redirect) {
		get_file(redirect);
		p = redirect;
	}
	spin_unlock(&redirect_lock);

	if (p) {
		ssize_t res;
		res = vfs_write(p, buf, count, &p->f_pos);
		fput(p);
		return res;
	}
	return tty_write(file, buf, count, ppos);
}

static char ptychar[] = "pqrstuvwxyzabcde";

1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180
/**
 *	pty_line_name	-	generate name for a pty
 *	@driver: the tty driver in use
 *	@index: the minor number
 *	@p: output buffer of at least 6 bytes
 *
 *	Generate a name from a driver reference and write it to the output
 *	buffer.
 *
 *	Locking: None
 */
static void pty_line_name(struct tty_driver *driver, int index, char *p)
L
Linus Torvalds 已提交
1181 1182 1183 1184
{
	int i = index + driver->name_base;
	/* ->name is initialized to "ttyp", but "tty" is expected */
	sprintf(p, "%s%c%x",
1185 1186
		driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
		ptychar[i >> 4 & 0xf], i & 0xf);
L
Linus Torvalds 已提交
1187 1188
}

1189
/**
A
Alan Cox 已提交
1190
 *	tty_line_name	-	generate name for a tty
1191 1192 1193 1194 1195 1196 1197 1198 1199 1200
 *	@driver: the tty driver in use
 *	@index: the minor number
 *	@p: output buffer of at least 7 bytes
 *
 *	Generate a name from a driver reference and write it to the output
 *	buffer.
 *
 *	Locking: None
 */
static void tty_line_name(struct tty_driver *driver, int index, char *p)
L
Linus Torvalds 已提交
1201 1202 1203 1204
{
	sprintf(p, "%s%d", driver->name, index + driver->name_base);
}

1205 1206 1207 1208
/**
 *	tty_driver_lookup_tty() - find an existing tty, if any
 *	@driver: the driver for the tty
 *	@idx:	 the minor number
1209
 *
1210
 *	Return the tty, if found or ERR_PTR() otherwise.
1211
 *
1212 1213 1214
 *	Locking: tty_mutex must be held. If tty is found, the mutex must
 *	be held until the 'fast-open' is also done. Will change once we
 *	have refcounting in the driver and per driver locking
1215
 */
1216 1217
struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
		struct inode *inode, int idx)
1218 1219 1220
{
	struct tty_struct *tty;

1221
	if (driver->ops->lookup)
1222
		return driver->ops->lookup(driver, inode, idx);
1223

A
Alan Cox 已提交
1224
	tty = driver->ttys[idx];
1225 1226 1227
	return tty;
}

1228 1229 1230 1231 1232 1233 1234 1235 1236 1237
/**
 *	tty_init_termios	-  helper for termios setup
 *	@tty: the tty to set up
 *
 *	Initialise the termios structures for this tty. Thus runs under
 *	the tty_mutex currently so we can be relaxed about ordering.
 */

int tty_init_termios(struct tty_struct *tty)
{
A
Alan Cox 已提交
1238
	struct ktermios *tp;
1239 1240 1241 1242
	int idx = tty->index;

	tp = tty->driver->termios[idx];
	if (tp == NULL) {
A
Alan Cox 已提交
1243 1244
		tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
		if (tp == NULL)
1245 1246 1247 1248 1249 1250
			return -ENOMEM;
		memcpy(tp, &tty->driver->init_termios,
						sizeof(struct ktermios));
		tty->driver->termios[idx] = tp;
	}
	tty->termios = tp;
A
Alan Cox 已提交
1251
	tty->termios_locked = tp + 1;
1252 1253 1254 1255 1256 1257 1258

	/* Compatibility until drivers always set this */
	tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
	tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
	return 0;
}

1259
/**
A
Alan Cox 已提交
1260 1261 1262 1263 1264
 *	tty_driver_install_tty() - install a tty entry in the driver
 *	@driver: the driver for the tty
 *	@tty: the tty
 *
 *	Install a tty object into the driver tables. The tty->index field
1265 1266 1267
 *	will be set by the time this is called. This method is responsible
 *	for ensuring any need additional structures are allocated and
 *	configured.
A
Alan Cox 已提交
1268 1269 1270 1271 1272 1273
 *
 *	Locking: tty_mutex for now
 */
static int tty_driver_install_tty(struct tty_driver *driver,
						struct tty_struct *tty)
{
1274 1275
	int idx = tty->index;

A
Alan Cox 已提交
1276 1277
	if (driver->ops->install)
		return driver->ops->install(driver, tty);
1278 1279 1280 1281 1282 1283 1284 1285

	if (tty_init_termios(tty) == 0) {
		tty_driver_kref_get(driver);
		tty->count++;
		driver->ttys[idx] = tty;
		return 0;
	}
	return -ENOMEM;
A
Alan Cox 已提交
1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
}

/**
 *	tty_driver_remove_tty() - remove a tty from the driver tables
 *	@driver: the driver for the tty
 *	@idx:	 the minor number
 *
 *	Remvoe a tty object from the driver tables. The tty->index field
 *	will be set by the time this is called.
 *
 *	Locking: tty_mutex for now
 */
static void tty_driver_remove_tty(struct tty_driver *driver,
						struct tty_struct *tty)
{
	if (driver->ops->remove)
		driver->ops->remove(driver, tty);
	else
		driver->ttys[tty->index] = NULL;
}

/*
 * 	tty_reopen()	- fast re-open of an open tty
 * 	@tty	- the tty to open
1310
 *
1311
 *	Return 0 on success, -errno on error.
1312
 *
1313 1314
 *	Locking: tty_mutex must be held from the time the tty was found
 *		 till this open completes.
1315
 */
1316
static int tty_reopen(struct tty_struct *tty)
1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336
{
	struct tty_driver *driver = tty->driver;

	if (test_bit(TTY_CLOSING, &tty->flags))
		return -EIO;

	if (driver->type == TTY_DRIVER_TYPE_PTY &&
	    driver->subtype == PTY_TYPE_MASTER) {
		/*
		 * special case for PTY masters: only one open permitted,
		 * and the slave side open count is incremented as well.
		 */
		if (tty->count)
			return -EIO;

		tty->link->count++;
	}
	tty->count++;
	tty->driver = driver; /* N.B. why do this every time?? */

1337
	WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1338 1339 1340 1341

	return 0;
}

1342
/**
1343
 *	tty_init_dev		-	initialise a tty device
1344 1345
 *	@driver: tty driver we are opening a device on
 *	@idx: device index
1346 1347
 *	@ret_tty: returned tty structure
 *	@first_ok: ok to open a new device (used by ptmx)
1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360
 *
 *	Prepare a tty device. This may not be a "new" clean device but
 *	could also be an active device. The pty drivers require special
 *	handling because of this.
 *
 *	Locking:
 *		The function is called under the tty_mutex, which
 *	protects us from the tty struct or driver itself going away.
 *
 *	On exit the tty device has the line discipline attached and
 *	a reference count of 1. If a pair was created for pty/tty use
 *	and the other was a pty master then it too has a reference count of 1.
 *
L
Linus Torvalds 已提交
1361
 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
I
Ingo Molnar 已提交
1362 1363
 * failed open.  The new code protects the open with a mutex, so it's
 * really quite straightforward.  The mutex locking can probably be
L
Linus Torvalds 已提交
1364 1365
 * relaxed for the (most common) case of reopening a tty.
 */
1366

1367 1368
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
								int first_ok)
L
Linus Torvalds 已提交
1369
{
1370
	struct tty_struct *tty;
1371
	int retval;
L
Linus Torvalds 已提交
1372

1373
	/* Check if pty master is being opened multiple times */
1374
	if (driver->subtype == PTY_TYPE_MASTER &&
1375 1376 1377
		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
		return ERR_PTR(-EIO);

L
Linus Torvalds 已提交
1378 1379 1380 1381
	/*
	 * First time open is complex, especially for PTY devices.
	 * This code guarantees that either everything succeeds and the
	 * TTY is ready for operation, or else the table slots are vacated
1382
	 * and the allocated memory released.  (Except that the termios
L
Linus Torvalds 已提交
1383 1384 1385
	 * and locked termios may be retained.)
	 */

1386 1387
	if (!try_module_get(driver->owner))
		return ERR_PTR(-ENODEV);
L
Linus Torvalds 已提交
1388 1389

	tty = alloc_tty_struct();
1390
	if (!tty)
L
Linus Torvalds 已提交
1391
		goto fail_no_mem;
1392
	initialize_tty_struct(tty, driver, idx);
L
Linus Torvalds 已提交
1393

1394
	retval = tty_driver_install_tty(driver, tty);
1395 1396 1397 1398 1399
	if (retval < 0) {
		free_tty_struct(tty);
		module_put(driver->owner);
		return ERR_PTR(retval);
	}
A
Alan Cox 已提交
1400

1401
	/*
L
Linus Torvalds 已提交
1402
	 * Structures all installed ... call the ldisc open routines.
1403 1404
	 * If we fail here just call release_tty to clean up.  No need
	 * to decrement the use counts, as release_tty doesn't care.
L
Linus Torvalds 已提交
1405 1406
	 */

1407
	retval = tty_ldisc_setup(tty, tty->link);
1408 1409
	if (retval)
		goto release_mem_out;
1410
	return tty;
L
Linus Torvalds 已提交
1411 1412 1413

fail_no_mem:
	module_put(driver->owner);
1414
	return ERR_PTR(-ENOMEM);
L
Linus Torvalds 已提交
1415

1416
	/* call the tty release_tty routine to clean out this slot */
L
Linus Torvalds 已提交
1417
release_mem_out:
1418
	if (printk_ratelimit())
1419
		printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1420
				 "clearing slot %d\n", idx);
1421
	release_tty(tty, idx);
1422
	return ERR_PTR(retval);
L
Linus Torvalds 已提交
1423 1424
}

A
Alan Cox 已提交
1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
void tty_free_termios(struct tty_struct *tty)
{
	struct ktermios *tp;
	int idx = tty->index;
	/* Kill this flag and push into drivers for locking etc */
	if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
		/* FIXME: Locking on ->termios array */
		tp = tty->termios;
		tty->driver->termios[idx] = NULL;
		kfree(tp);
	}
}
EXPORT_SYMBOL(tty_free_termios);

void tty_shutdown(struct tty_struct *tty)
{
A
Alan Cox 已提交
1441
	tty_driver_remove_tty(tty->driver, tty);
A
Alan Cox 已提交
1442 1443 1444 1445
	tty_free_termios(tty);
}
EXPORT_SYMBOL(tty_shutdown);

1446
/**
1447
 *	release_one_tty		-	release tty structure memory
A
Alan Cox 已提交
1448
 *	@kref: kref of tty we are obliterating
1449 1450 1451 1452 1453 1454 1455 1456 1457
 *
 *	Releases memory associated with a tty structure, and clears out the
 *	driver table slots. This function is called when a device is no longer
 *	in use. It also gets called when setup of a device fails.
 *
 *	Locking:
 *		tty_mutex - sometimes only
 *		takes the file list lock internally when working on the list
 *	of ttys that the driver keeps.
L
Linus Torvalds 已提交
1458
 */
A
Alan Cox 已提交
1459
static void release_one_tty(struct kref *kref)
L
Linus Torvalds 已提交
1460
{
A
Alan Cox 已提交
1461
	struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1462
	struct tty_driver *driver = tty->driver;
1463

A
Alan Cox 已提交
1464 1465 1466 1467
	if (tty->ops->shutdown)
		tty->ops->shutdown(tty);
	else
		tty_shutdown(tty);
L
Linus Torvalds 已提交
1468
	tty->magic = 0;
A
Alan Cox 已提交
1469
	tty_driver_kref_put(driver);
1470
	module_put(driver->owner);
1471

L
Linus Torvalds 已提交
1472 1473 1474
	file_list_lock();
	list_del_init(&tty->tty_files);
	file_list_unlock();
1475

L
Linus Torvalds 已提交
1476 1477 1478
	free_tty_struct(tty);
}

A
Alan Cox 已提交
1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493
/**
 *	tty_kref_put		-	release a tty kref
 *	@tty: tty device
 *
 *	Release a reference to a tty device and if need be let the kref
 *	layer destruct the object for us
 */

void tty_kref_put(struct tty_struct *tty)
{
	if (tty)
		kref_put(&tty->kref, release_one_tty);
}
EXPORT_SYMBOL(tty_kref_put);

1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504
/**
 *	release_tty		-	release tty structure memory
 *
 *	Release both @tty and a possible linked partner (think pty pair),
 *	and decrement the refcount of the backing module.
 *
 *	Locking:
 *		tty_mutex - sometimes only
 *		takes the file list lock internally when working on the list
 *	of ttys that the driver keeps.
 *		FIXME: should we require tty_mutex is held here ??
A
Alan Cox 已提交
1505
 *
1506 1507 1508
 */
static void release_tty(struct tty_struct *tty, int idx)
{
A
Alan Cox 已提交
1509 1510 1511
	/* This should always be true but check for the moment */
	WARN_ON(tty->index != idx);

1512
	if (tty->link)
A
Alan Cox 已提交
1513 1514
		tty_kref_put(tty->link);
	tty_kref_put(tty);
1515 1516
}

L
Linus Torvalds 已提交
1517 1518 1519 1520 1521 1522 1523 1524
/*
 * Even releasing the tty structures is a tricky business.. We have
 * to be very careful that the structures are all released at the
 * same time, as interrupts might otherwise get the wrong pointers.
 *
 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
 * lead to double frees or releasing memory still in use.
 */
1525
void tty_release_dev(struct file *filp)
L
Linus Torvalds 已提交
1526 1527 1528
{
	struct tty_struct *tty, *o_tty;
	int	pty_master, tty_closing, o_tty_closing, do_sleep;
1529
	int	devpts;
L
Linus Torvalds 已提交
1530 1531
	int	idx;
	char	buf[64];
1532
	struct 	inode *inode;
1533

1534
	inode = filp->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1535
	tty = (struct tty_struct *)filp->private_data;
1536
	if (tty_paranoia_check(tty, inode, "tty_release_dev"))
L
Linus Torvalds 已提交
1537 1538
		return;

1539
	check_tty_count(tty, "tty_release_dev");
L
Linus Torvalds 已提交
1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550

	tty_fasync(-1, filp, 0);

	idx = tty->index;
	pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
		      tty->driver->subtype == PTY_TYPE_MASTER);
	devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
	o_tty = tty->link;

#ifdef TTY_PARANOIA_CHECK
	if (idx < 0 || idx >= tty->driver->num) {
1551
		printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
L
Linus Torvalds 已提交
1552 1553 1554
				  "free (%s)\n", tty->name);
		return;
	}
A
Alan Cox 已提交
1555
	if (!devpts) {
L
Linus Torvalds 已提交
1556
		if (tty != tty->driver->ttys[idx]) {
1557
			printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
L
Linus Torvalds 已提交
1558 1559 1560 1561
			       "for (%s)\n", idx, tty->name);
			return;
		}
		if (tty->termios != tty->driver->termios[idx]) {
1562
			printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
L
Linus Torvalds 已提交
1563 1564 1565 1566 1567 1568 1569 1570
			       "for (%s)\n",
			       idx, tty->name);
			return;
		}
	}
#endif

#ifdef TTY_DEBUG_HANGUP
1571
	printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
L
Linus Torvalds 已提交
1572 1573 1574 1575 1576 1577 1578
	       tty_name(tty, buf), tty->count);
#endif

#ifdef TTY_PARANOIA_CHECK
	if (tty->driver->other &&
	     !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
		if (o_tty != tty->driver->other->ttys[idx]) {
1579
			printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
L
Linus Torvalds 已提交
1580 1581 1582 1583 1584
					  "not o_tty for (%s)\n",
			       idx, tty->name);
			return;
		}
		if (o_tty->termios != tty->driver->other->termios[idx]) {
1585
			printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
L
Linus Torvalds 已提交
1586 1587 1588 1589 1590
					  "not o_termios for (%s)\n",
			       idx, tty->name);
			return;
		}
		if (o_tty->link != tty) {
1591
			printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
L
Linus Torvalds 已提交
1592 1593 1594 1595
			return;
		}
	}
#endif
A
Alan Cox 已提交
1596 1597
	if (tty->ops->close)
		tty->ops->close(tty, filp);
L
Linus Torvalds 已提交
1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618

	/*
	 * Sanity check: if tty->count is going to zero, there shouldn't be
	 * any waiters on tty->read_wait or tty->write_wait.  We test the
	 * wait queues and kick everyone out _before_ actually starting to
	 * close.  This ensures that we won't block while releasing the tty
	 * structure.
	 *
	 * The test for the o_tty closing is necessary, since the master and
	 * slave sides may close in any order.  If the slave side closes out
	 * first, its count will be one, since the master side holds an open.
	 * Thus this test wouldn't be triggered at the time the slave closes,
	 * so we do it now.
	 *
	 * Note that it's possible for the tty to be opened again while we're
	 * flushing out waiters.  By recalculating the closing flags before
	 * each iteration we avoid any problems.
	 */
	while (1) {
		/* Guard against races with tty->count changes elsewhere and
		   opens on /dev/tty */
1619

I
Ingo Molnar 已提交
1620
		mutex_lock(&tty_mutex);
L
Linus Torvalds 已提交
1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648
		tty_closing = tty->count <= 1;
		o_tty_closing = o_tty &&
			(o_tty->count <= (pty_master ? 1 : 0));
		do_sleep = 0;

		if (tty_closing) {
			if (waitqueue_active(&tty->read_wait)) {
				wake_up(&tty->read_wait);
				do_sleep++;
			}
			if (waitqueue_active(&tty->write_wait)) {
				wake_up(&tty->write_wait);
				do_sleep++;
			}
		}
		if (o_tty_closing) {
			if (waitqueue_active(&o_tty->read_wait)) {
				wake_up(&o_tty->read_wait);
				do_sleep++;
			}
			if (waitqueue_active(&o_tty->write_wait)) {
				wake_up(&o_tty->write_wait);
				do_sleep++;
			}
		}
		if (!do_sleep)
			break;

1649
		printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
L
Linus Torvalds 已提交
1650
				    "active!\n", tty_name(tty, buf));
I
Ingo Molnar 已提交
1651
		mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
1652
		schedule();
1653
	}
L
Linus Torvalds 已提交
1654 1655

	/*
1656 1657
	 * The closing flags are now consistent with the open counts on
	 * both sides, and we've completed the last operation that could
L
Linus Torvalds 已提交
1658 1659 1660 1661
	 * block, so it's safe to proceed with closing.
	 */
	if (pty_master) {
		if (--o_tty->count < 0) {
1662
			printk(KERN_WARNING "tty_release_dev: bad pty slave count "
L
Linus Torvalds 已提交
1663 1664 1665 1666 1667 1668
					    "(%d) for %s\n",
			       o_tty->count, tty_name(o_tty, buf));
			o_tty->count = 0;
		}
	}
	if (--tty->count < 0) {
1669
		printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
L
Linus Torvalds 已提交
1670 1671 1672
		       tty->count, tty_name(tty, buf));
		tty->count = 0;
	}
1673

L
Linus Torvalds 已提交
1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692
	/*
	 * We've decremented tty->count, so we need to remove this file
	 * descriptor off the tty->tty_files list; this serves two
	 * purposes:
	 *  - check_tty_count sees the correct number of file descriptors
	 *    associated with this tty.
	 *  - do_tty_hangup no longer sees this file descriptor as
	 *    something that needs to be handled for hangups.
	 */
	file_kill(filp);
	filp->private_data = NULL;

	/*
	 * Perform some housekeeping before deciding whether to return.
	 *
	 * Set the TTY_CLOSING flag if this was the last open.  In the
	 * case of a pty we may have to wait around for the other side
	 * to close, and TTY_CLOSING makes sure we can't be reopened.
	 */
1693
	if (tty_closing)
L
Linus Torvalds 已提交
1694
		set_bit(TTY_CLOSING, &tty->flags);
1695
	if (o_tty_closing)
L
Linus Torvalds 已提交
1696 1697 1698 1699 1700 1701 1702 1703 1704
		set_bit(TTY_CLOSING, &o_tty->flags);

	/*
	 * If _either_ side is closing, make sure there aren't any
	 * processes that still think tty or o_tty is their controlling
	 * tty.
	 */
	if (tty_closing || o_tty_closing) {
		read_lock(&tasklist_lock);
1705
		session_clear_tty(tty->session);
L
Linus Torvalds 已提交
1706
		if (o_tty)
1707
			session_clear_tty(o_tty->session);
L
Linus Torvalds 已提交
1708 1709 1710
		read_unlock(&tasklist_lock);
	}

I
Ingo Molnar 已提交
1711
	mutex_unlock(&tty_mutex);
P
Paul Fulghum 已提交
1712

L
Linus Torvalds 已提交
1713 1714 1715
	/* check whether both sides are closing ... */
	if (!tty_closing || (o_tty && !o_tty_closing))
		return;
1716

L
Linus Torvalds 已提交
1717 1718 1719 1720
#ifdef TTY_DEBUG_HANGUP
	printk(KERN_DEBUG "freeing tty structure...");
#endif
	/*
1721
	 * Ask the line discipline code to release its structures
L
Linus Torvalds 已提交
1722
	 */
1723
	tty_ldisc_release(tty, o_tty);
L
Linus Torvalds 已提交
1724
	/*
1725
	 * The release_tty function takes care of the details of clearing
L
Linus Torvalds 已提交
1726 1727
	 * the slots and preserving the termios structure.
	 */
1728
	release_tty(tty, idx);
L
Linus Torvalds 已提交
1729 1730

	/* Make this pty number available for reallocation */
1731
	if (devpts)
1732
		devpts_kill_index(inode, idx);
L
Linus Torvalds 已提交
1733 1734
}

1735
/**
1736
 *	__tty_open		-	open a tty device
1737 1738
 *	@inode: inode of device file
 *	@filp: file pointer to tty
L
Linus Torvalds 已提交
1739
 *
1740 1741 1742
 *	tty_open and tty_release keep up the tty count that contains the
 *	number of opens done on a tty. We cannot use the inode-count, as
 *	different inodes might point to the same tty.
L
Linus Torvalds 已提交
1743
 *
1744 1745 1746 1747 1748 1749 1750
 *	Open-counting is needed for pty masters, as well as for keeping
 *	track of serial lines: DTR is dropped when the last close happens.
 *	(This is not done solely through tty->count, now.  - Ted 1/27/92)
 *
 *	The termios state of a pty is reset on first open so that
 *	settings don't persist across reuse.
 *
1751
 *	Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1752 1753
 *		 tty->count should protect the rest.
 *		 ->siglock protects ->signal/->sighand
L
Linus Torvalds 已提交
1754
 */
1755

1756
static int __tty_open(struct inode *inode, struct file *filp)
L
Linus Torvalds 已提交
1757
{
1758
	struct tty_struct *tty = NULL;
L
Linus Torvalds 已提交
1759 1760 1761 1762 1763 1764 1765
	int noctty, retval;
	struct tty_driver *driver;
	int index;
	dev_t device = inode->i_rdev;
	unsigned short saved_flags = filp->f_flags;

	nonseekable_open(inode, filp);
1766

L
Linus Torvalds 已提交
1767 1768 1769 1770
retry_open:
	noctty = filp->f_flags & O_NOCTTY;
	index  = -1;
	retval = 0;
1771

I
Ingo Molnar 已提交
1772
	mutex_lock(&tty_mutex);
L
Linus Torvalds 已提交
1773

1774
	if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1775 1776
		tty = get_current_tty();
		if (!tty) {
I
Ingo Molnar 已提交
1777
			mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
1778 1779
			return -ENXIO;
		}
A
Alan Cox 已提交
1780
		driver = tty_driver_kref_get(tty->driver);
1781
		index = tty->index;
L
Linus Torvalds 已提交
1782 1783
		filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
		/* noctty = 1; */
A
Alan Cox 已提交
1784 1785
		/* FIXME: Should we take a driver reference ? */
		tty_kref_put(tty);
L
Linus Torvalds 已提交
1786 1787 1788
		goto got_driver;
	}
#ifdef CONFIG_VT
1789
	if (device == MKDEV(TTY_MAJOR, 0)) {
L
Linus Torvalds 已提交
1790
		extern struct tty_driver *console_driver;
A
Alan Cox 已提交
1791
		driver = tty_driver_kref_get(console_driver);
L
Linus Torvalds 已提交
1792 1793 1794 1795 1796
		index = fg_console;
		noctty = 1;
		goto got_driver;
	}
#endif
1797
	if (device == MKDEV(TTYAUX_MAJOR, 1)) {
A
Alan Cox 已提交
1798
		driver = tty_driver_kref_get(console_device(&index));
L
Linus Torvalds 已提交
1799 1800 1801 1802 1803 1804
		if (driver) {
			/* Don't let /dev/console block */
			filp->f_flags |= O_NONBLOCK;
			noctty = 1;
			goto got_driver;
		}
I
Ingo Molnar 已提交
1805
		mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
1806 1807 1808 1809 1810
		return -ENODEV;
	}

	driver = get_tty_driver(device, &index);
	if (!driver) {
I
Ingo Molnar 已提交
1811
		mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
1812 1813 1814
		return -ENODEV;
	}
got_driver:
1815 1816
	if (!tty) {
		/* check whether we're reopening an existing tty */
1817
		tty = tty_driver_lookup_tty(driver, inode, index);
1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829

		if (IS_ERR(tty))
			return PTR_ERR(tty);
	}

	if (tty) {
		retval = tty_reopen(tty);
		if (retval)
			tty = ERR_PTR(retval);
	} else
		tty = tty_init_dev(driver, index, 0);

I
Ingo Molnar 已提交
1830
	mutex_unlock(&tty_mutex);
A
Alan Cox 已提交
1831
	tty_driver_kref_put(driver);
1832 1833
	if (IS_ERR(tty))
		return PTR_ERR(tty);
L
Linus Torvalds 已提交
1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844

	filp->private_data = tty;
	file_move(filp, &tty->tty_files);
	check_tty_count(tty, "tty_open");
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_MASTER)
		noctty = 1;
#ifdef TTY_DEBUG_HANGUP
	printk(KERN_DEBUG "opening %s...", tty->name);
#endif
	if (!retval) {
A
Alan Cox 已提交
1845 1846
		if (tty->ops->open)
			retval = tty->ops->open(tty, filp);
L
Linus Torvalds 已提交
1847 1848 1849 1850 1851
		else
			retval = -ENODEV;
	}
	filp->f_flags = saved_flags;

1852 1853
	if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
						!capable(CAP_SYS_ADMIN))
L
Linus Torvalds 已提交
1854 1855 1856 1857 1858 1859 1860
		retval = -EBUSY;

	if (retval) {
#ifdef TTY_DEBUG_HANGUP
		printk(KERN_DEBUG "error %d in opening %s...", retval,
		       tty->name);
#endif
1861
		tty_release_dev(filp);
L
Linus Torvalds 已提交
1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873
		if (retval != -ERESTARTSYS)
			return retval;
		if (signal_pending(current))
			return retval;
		schedule();
		/*
		 * Need to reset f_op in case a hangup happened.
		 */
		if (filp->f_op == &hung_up_tty_fops)
			filp->f_op = &tty_fops;
		goto retry_open;
	}
1874 1875 1876

	mutex_lock(&tty_mutex);
	spin_lock_irq(&current->sighand->siglock);
L
Linus Torvalds 已提交
1877 1878 1879
	if (!noctty &&
	    current->signal->leader &&
	    !current->signal->tty &&
1880
	    tty->session == NULL)
1881
		__proc_set_tty(current, tty);
1882 1883
	spin_unlock_irq(&current->sighand->siglock);
	mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
1884 1885 1886
	return 0;
}

1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899
/* BKL pushdown: scary code avoidance wrapper */
static int tty_open(struct inode *inode, struct file *filp)
{
	int ret;

	lock_kernel();
	ret = __tty_open(inode, filp);
	unlock_kernel();
	return ret;
}



L
Linus Torvalds 已提交
1900

1901 1902 1903 1904 1905 1906 1907 1908 1909
/**
 *	tty_release		-	vfs callback for close
 *	@inode: inode of tty
 *	@filp: file pointer for handle to tty
 *
 *	Called the last time each file handle is closed that references
 *	this tty. There may however be several such references.
 *
 *	Locking:
1910
 *		Takes bkl. See tty_release_dev
1911 1912
 */

1913
static int tty_release(struct inode *inode, struct file *filp)
L
Linus Torvalds 已提交
1914 1915
{
	lock_kernel();
1916
	tty_release_dev(filp);
L
Linus Torvalds 已提交
1917 1918 1919 1920
	unlock_kernel();
	return 0;
}

1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932
/**
 *	tty_poll	-	check tty status
 *	@filp: file being polled
 *	@wait: poll wait structures to update
 *
 *	Call the line discipline polling method to obtain the poll
 *	status of the device.
 *
 *	Locking: locks called line discipline but ldisc poll method
 *	may be re-entered freely by other callers.
 */

1933
static unsigned int tty_poll(struct file *filp, poll_table *wait)
L
Linus Torvalds 已提交
1934
{
1935
	struct tty_struct *tty;
L
Linus Torvalds 已提交
1936 1937 1938 1939
	struct tty_ldisc *ld;
	int ret = 0;

	tty = (struct tty_struct *)filp->private_data;
1940
	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
L
Linus Torvalds 已提交
1941
		return 0;
1942

L
Linus Torvalds 已提交
1943
	ld = tty_ldisc_ref_wait(tty);
A
Alan Cox 已提交
1944 1945
	if (ld->ops->poll)
		ret = (ld->ops->poll)(tty, filp, wait);
L
Linus Torvalds 已提交
1946 1947 1948 1949
	tty_ldisc_deref(ld);
	return ret;
}

1950
static int tty_fasync(int fd, struct file *filp, int on)
L
Linus Torvalds 已提交
1951
{
1952
	struct tty_struct *tty;
A
Alan Cox 已提交
1953
	unsigned long flags;
J
Jonathan Corbet 已提交
1954
	int retval = 0;
L
Linus Torvalds 已提交
1955

J
Jonathan Corbet 已提交
1956
	lock_kernel();
L
Linus Torvalds 已提交
1957
	tty = (struct tty_struct *)filp->private_data;
1958
	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
J
Jonathan Corbet 已提交
1959
		goto out;
1960

L
Linus Torvalds 已提交
1961 1962
	retval = fasync_helper(fd, filp, on, &tty->fasync);
	if (retval <= 0)
J
Jonathan Corbet 已提交
1963
		goto out;
L
Linus Torvalds 已提交
1964 1965

	if (on) {
1966 1967
		enum pid_type type;
		struct pid *pid;
L
Linus Torvalds 已提交
1968 1969
		if (!waitqueue_active(&tty->read_wait))
			tty->minimum_to_wake = 1;
A
Alan Cox 已提交
1970
		spin_lock_irqsave(&tty->ctrl_lock, flags);
1971 1972 1973 1974 1975 1976 1977
		if (tty->pgrp) {
			pid = tty->pgrp;
			type = PIDTYPE_PGID;
		} else {
			pid = task_pid(current);
			type = PIDTYPE_PID;
		}
A
Alan Cox 已提交
1978
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1979
		retval = __f_setown(filp, pid, type, 0);
L
Linus Torvalds 已提交
1980
		if (retval)
J
Jonathan Corbet 已提交
1981
			goto out;
L
Linus Torvalds 已提交
1982 1983 1984 1985
	} else {
		if (!tty->fasync && !waitqueue_active(&tty->read_wait))
			tty->minimum_to_wake = N_TTY_BUF_SIZE;
	}
J
Jonathan Corbet 已提交
1986 1987 1988 1989
	retval = 0;
out:
	unlock_kernel();
	return retval;
L
Linus Torvalds 已提交
1990 1991
}

1992 1993 1994 1995 1996
/**
 *	tiocsti			-	fake input character
 *	@tty: tty to fake input into
 *	@p: pointer to character
 *
1997
 *	Fake input to a tty device. Does the necessary locking and
1998 1999 2000 2001 2002 2003 2004
 *	input management.
 *
 *	FIXME: does not honour flow control ??
 *
 *	Locking:
 *		Called functions take tty_ldisc_lock
 *		current->signal->tty check is safe without locks
2005 2006
 *
 *	FIXME: may race normal receive processing
2007 2008
 */

L
Linus Torvalds 已提交
2009 2010 2011 2012
static int tiocsti(struct tty_struct *tty, char __user *p)
{
	char ch, mbz = 0;
	struct tty_ldisc *ld;
2013

L
Linus Torvalds 已提交
2014 2015 2016 2017 2018
	if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (get_user(ch, p))
		return -EFAULT;
	ld = tty_ldisc_ref_wait(tty);
A
Alan Cox 已提交
2019
	ld->ops->receive_buf(tty, &ch, &mbz, 1);
L
Linus Torvalds 已提交
2020 2021 2022 2023
	tty_ldisc_deref(ld);
	return 0;
}

2024 2025 2026 2027 2028
/**
 *	tiocgwinsz		-	implement window query ioctl
 *	@tty; tty
 *	@arg: user buffer for result
 *
A
Alan Cox 已提交
2029
 *	Copies the kernel idea of the window size into the user buffer.
2030
 *
2031
 *	Locking: tty->termios_mutex is taken to ensure the winsize data
A
Alan Cox 已提交
2032
 *		is consistent.
2033 2034
 */

2035
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
L
Linus Torvalds 已提交
2036
{
A
Alan Cox 已提交
2037 2038
	int err;

2039
	mutex_lock(&tty->termios_mutex);
A
Alan Cox 已提交
2040
	err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2041
	mutex_unlock(&tty->termios_mutex);
A
Alan Cox 已提交
2042 2043

	return err ? -EFAULT: 0;
L
Linus Torvalds 已提交
2044 2045
}

2046
/**
2047 2048
 *	tty_do_resize		-	resize event
 *	@tty: tty being resized
2049
 *	@real_tty: real tty (not the same as tty if using a pty/tty pair)
2050 2051 2052 2053 2054
 *	@rows: rows (character)
 *	@cols: cols (character)
 *
 *	Update the termios variables and send the neccessary signals to
 *	peform a terminal resize correctly
2055 2056
 */

2057 2058
int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
					struct winsize *ws)
L
Linus Torvalds 已提交
2059
{
A
Alan Cox 已提交
2060 2061
	struct pid *pgrp, *rpgrp;
	unsigned long flags;
L
Linus Torvalds 已提交
2062

2063 2064
	/* For a PTY we need to lock the tty side */
	mutex_lock(&real_tty->termios_mutex);
A
Alan Cox 已提交
2065
	if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
A
Alan Cox 已提交
2066
		goto done;
A
Alan Cox 已提交
2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081
	/* Get the PID values and reference them so we can
	   avoid holding the tty ctrl lock while sending signals */
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	pgrp = get_pid(tty->pgrp);
	rpgrp = get_pid(real_tty->pgrp);
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	if (pgrp)
		kill_pgrp(pgrp, SIGWINCH, 1);
	if (rpgrp != pgrp && rpgrp)
		kill_pgrp(rpgrp, SIGWINCH, 1);

	put_pid(pgrp);
	put_pid(rpgrp);

2082 2083
	tty->winsize = *ws;
	real_tty->winsize = *ws;
A
Alan Cox 已提交
2084
done:
2085
	mutex_unlock(&real_tty->termios_mutex);
L
Linus Torvalds 已提交
2086 2087 2088
	return 0;
}

2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116
/**
 *	tiocswinsz		-	implement window size set ioctl
 *	@tty; tty
 *	@arg: user buffer for result
 *
 *	Copies the user idea of the window size to the kernel. Traditionally
 *	this is just advisory information but for the Linux console it
 *	actually has driver level meaning and triggers a VC resize.
 *
 *	Locking:
 *		Driver dependant. The default do_resize method takes the
 *	tty termios mutex and ctrl_lock. The console takes its own lock
 *	then calls into the default method.
 */

static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
	struct winsize __user *arg)
{
	struct winsize tmp_ws;
	if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
		return -EFAULT;

	if (tty->ops->resize)
		return tty->ops->resize(tty, real_tty, &tmp_ws);
	else
		return tty_do_resize(tty, real_tty, &tmp_ws);
}

2117 2118 2119 2120 2121 2122 2123 2124 2125
/**
 *	tioccons	-	allow admin to move logical console
 *	@file: the file to become console
 *
 *	Allow the adminstrator to move the redirected console device
 *
 *	Locking: uses redirect_lock to guard the redirect information
 */

L
Linus Torvalds 已提交
2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150
static int tioccons(struct file *file)
{
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (file->f_op->write == redirected_tty_write) {
		struct file *f;
		spin_lock(&redirect_lock);
		f = redirect;
		redirect = NULL;
		spin_unlock(&redirect_lock);
		if (f)
			fput(f);
		return 0;
	}
	spin_lock(&redirect_lock);
	if (redirect) {
		spin_unlock(&redirect_lock);
		return -EBUSY;
	}
	get_file(file);
	redirect = file;
	spin_unlock(&redirect_lock);
	return 0;
}

2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161
/**
 *	fionbio		-	non blocking ioctl
 *	@file: file to set blocking value
 *	@p: user parameter
 *
 *	Historical tty interfaces had a blocking control ioctl before
 *	the generic functionality existed. This piece of history is preserved
 *	in the expected tty API of posix OS's.
 *
 *	Locking: none, the open fle handle ensures it won't go away.
 */
L
Linus Torvalds 已提交
2162 2163 2164 2165 2166 2167 2168 2169

static int fionbio(struct file *file, int __user *p)
{
	int nonblock;

	if (get_user(nonblock, p))
		return -EFAULT;

A
Alan Cox 已提交
2170 2171
	/* file->f_flags is still BKL protected in the fs layer - vomit */
	lock_kernel();
L
Linus Torvalds 已提交
2172 2173 2174 2175
	if (nonblock)
		file->f_flags |= O_NONBLOCK;
	else
		file->f_flags &= ~O_NONBLOCK;
A
Alan Cox 已提交
2176
	unlock_kernel();
L
Linus Torvalds 已提交
2177 2178 2179
	return 0;
}

2180 2181 2182 2183 2184 2185 2186 2187 2188
/**
 *	tiocsctty	-	set controlling tty
 *	@tty: tty structure
 *	@arg: user argument
 *
 *	This ioctl is used to manage job control. It permits a session
 *	leader to set this tty as the controlling tty for the session.
 *
 *	Locking:
2189
 *		Takes tty_mutex() to protect tty instance
2190 2191
 *		Takes tasklist_lock internally to walk sessions
 *		Takes ->siglock() when updating signal->tty
2192 2193
 */

L
Linus Torvalds 已提交
2194 2195
static int tiocsctty(struct tty_struct *tty, int arg)
{
2196
	int ret = 0;
2197
	if (current->signal->leader && (task_session(current) == tty->session))
2198 2199 2200
		return ret;

	mutex_lock(&tty_mutex);
L
Linus Torvalds 已提交
2201 2202 2203 2204
	/*
	 * The process must be a session leader and
	 * not have a controlling tty already.
	 */
2205 2206 2207 2208 2209
	if (!current->signal->leader || current->signal->tty) {
		ret = -EPERM;
		goto unlock;
	}

2210
	if (tty->session) {
L
Linus Torvalds 已提交
2211 2212 2213 2214
		/*
		 * This tty is already the controlling
		 * tty for another session group!
		 */
2215
		if (arg == 1 && capable(CAP_SYS_ADMIN)) {
L
Linus Torvalds 已提交
2216 2217 2218 2219
			/*
			 * Steal it away
			 */
			read_lock(&tasklist_lock);
2220
			session_clear_tty(tty->session);
L
Linus Torvalds 已提交
2221
			read_unlock(&tasklist_lock);
2222 2223 2224 2225
		} else {
			ret = -EPERM;
			goto unlock;
		}
L
Linus Torvalds 已提交
2226
	}
2227 2228
	proc_set_tty(current, tty);
unlock:
2229
	mutex_unlock(&tty_mutex);
2230
	return ret;
L
Linus Torvalds 已提交
2231 2232
}

2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253
/**
 *	tty_get_pgrp	-	return a ref counted pgrp pid
 *	@tty: tty to read
 *
 *	Returns a refcounted instance of the pid struct for the process
 *	group controlling the tty.
 */

struct pid *tty_get_pgrp(struct tty_struct *tty)
{
	unsigned long flags;
	struct pid *pgrp;

	spin_lock_irqsave(&tty->ctrl_lock, flags);
	pgrp = get_pid(tty->pgrp);
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	return pgrp;
}
EXPORT_SYMBOL_GPL(tty_get_pgrp);

2254 2255 2256 2257 2258 2259 2260 2261 2262
/**
 *	tiocgpgrp		-	get process group
 *	@tty: tty passed by user
 *	@real_tty: tty side of the tty pased by the user if a pty else the tty
 *	@p: returned pid
 *
 *	Obtain the process group of the tty. If there is no process group
 *	return an error.
 *
2263
 *	Locking: none. Reference to current->signal->tty is safe.
2264 2265
 */

L
Linus Torvalds 已提交
2266 2267
static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
2268 2269
	struct pid *pid;
	int ret;
L
Linus Torvalds 已提交
2270 2271 2272 2273 2274 2275
	/*
	 * (tty == real_tty) is a cheap way of
	 * testing if the tty is NOT a master pty.
	 */
	if (tty == real_tty && current->signal->tty != real_tty)
		return -ENOTTY;
2276 2277 2278 2279
	pid = tty_get_pgrp(real_tty);
	ret =  put_user(pid_vnr(pid), p);
	put_pid(pid);
	return ret;
L
Linus Torvalds 已提交
2280 2281
}

2282 2283 2284 2285 2286 2287 2288 2289 2290
/**
 *	tiocspgrp		-	attempt to set process group
 *	@tty: tty passed by user
 *	@real_tty: tty side device matching tty passed by user
 *	@p: pid pointer
 *
 *	Set the process group of the tty to the session passed. Only
 *	permitted where the tty session is our session.
 *
A
Alan Cox 已提交
2291
 *	Locking: RCU, ctrl lock
2292 2293
 */

L
Linus Torvalds 已提交
2294 2295
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
2296 2297
	struct pid *pgrp;
	pid_t pgrp_nr;
L
Linus Torvalds 已提交
2298
	int retval = tty_check_change(real_tty);
A
Alan Cox 已提交
2299
	unsigned long flags;
L
Linus Torvalds 已提交
2300 2301 2302 2303 2304 2305 2306

	if (retval == -EIO)
		return -ENOTTY;
	if (retval)
		return retval;
	if (!current->signal->tty ||
	    (current->signal->tty != real_tty) ||
2307
	    (real_tty->session != task_session(current)))
L
Linus Torvalds 已提交
2308
		return -ENOTTY;
2309
	if (get_user(pgrp_nr, p))
L
Linus Torvalds 已提交
2310
		return -EFAULT;
2311
	if (pgrp_nr < 0)
L
Linus Torvalds 已提交
2312
		return -EINVAL;
2313
	rcu_read_lock();
2314
	pgrp = find_vpid(pgrp_nr);
2315 2316 2317 2318 2319 2320 2321
	retval = -ESRCH;
	if (!pgrp)
		goto out_unlock;
	retval = -EPERM;
	if (session_of_pgrp(pgrp) != task_session(current))
		goto out_unlock;
	retval = 0;
A
Alan Cox 已提交
2322
	spin_lock_irqsave(&tty->ctrl_lock, flags);
2323 2324
	put_pid(real_tty->pgrp);
	real_tty->pgrp = get_pid(pgrp);
A
Alan Cox 已提交
2325
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2326 2327 2328
out_unlock:
	rcu_read_unlock();
	return retval;
L
Linus Torvalds 已提交
2329 2330
}

2331 2332 2333 2334 2335 2336 2337 2338 2339
/**
 *	tiocgsid		-	get session id
 *	@tty: tty passed by user
 *	@real_tty: tty side of the tty pased by the user if a pty else the tty
 *	@p: pointer to returned session id
 *
 *	Obtain the session id of the tty. If there is no session
 *	return an error.
 *
2340
 *	Locking: none. Reference to current->signal->tty is safe.
2341 2342
 */

L
Linus Torvalds 已提交
2343 2344 2345 2346 2347 2348 2349 2350
static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
	/*
	 * (tty == real_tty) is a cheap way of
	 * testing if the tty is NOT a master pty.
	*/
	if (tty == real_tty && current->signal->tty != real_tty)
		return -ENOTTY;
2351
	if (!real_tty->session)
L
Linus Torvalds 已提交
2352
		return -ENOTTY;
2353
	return put_user(pid_vnr(real_tty->session), p);
L
Linus Torvalds 已提交
2354 2355
}

2356 2357 2358 2359 2360 2361 2362 2363 2364 2365
/**
 *	tiocsetd	-	set line discipline
 *	@tty: tty device
 *	@p: pointer to user data
 *
 *	Set the line discipline according to user request.
 *
 *	Locking: see tty_set_ldisc, this function is just a helper
 */

L
Linus Torvalds 已提交
2366 2367 2368
static int tiocsetd(struct tty_struct *tty, int __user *p)
{
	int ldisc;
A
Alan Cox 已提交
2369
	int ret;
L
Linus Torvalds 已提交
2370 2371 2372

	if (get_user(ldisc, p))
		return -EFAULT;
A
Alan Cox 已提交
2373 2374 2375 2376 2377 2378

	lock_kernel();
	ret = tty_set_ldisc(tty, ldisc);
	unlock_kernel();

	return ret;
L
Linus Torvalds 已提交
2379 2380
}

2381 2382 2383 2384 2385 2386 2387 2388 2389
/**
 *	send_break	-	performed time break
 *	@tty: device to break on
 *	@duration: timeout in mS
 *
 *	Perform a timed break on hardware that lacks its own driver level
 *	timed break functionality.
 *
 *	Locking:
2390
 *		atomic_write_lock serializes
2391 2392 2393
 *
 */

2394
static int send_break(struct tty_struct *tty, unsigned int duration)
L
Linus Torvalds 已提交
2395
{
A
Alan Cox 已提交
2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418
	int retval;

	if (tty->ops->break_ctl == NULL)
		return 0;

	if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
		retval = tty->ops->break_ctl(tty, duration);
	else {
		/* Do the work ourselves */
		if (tty_write_lock(tty, 0) < 0)
			return -EINTR;
		retval = tty->ops->break_ctl(tty, -1);
		if (retval)
			goto out;
		if (!signal_pending(current))
			msleep_interruptible(duration);
		retval = tty->ops->break_ctl(tty, 0);
out:
		tty_write_unlock(tty);
		if (signal_pending(current))
			retval = -EINTR;
	}
	return retval;
L
Linus Torvalds 已提交
2419 2420
}

2421
/**
A
Alan Cox 已提交
2422
 *	tty_tiocmget		-	get modem status
2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433
 *	@tty: tty device
 *	@file: user file pointer
 *	@p: pointer to result
 *
 *	Obtain the modem status bits from the tty driver if the feature
 *	is supported. Return -EINVAL if it is not available.
 *
 *	Locking: none (up to the driver)
 */

static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
L
Linus Torvalds 已提交
2434 2435 2436
{
	int retval = -EINVAL;

A
Alan Cox 已提交
2437 2438
	if (tty->ops->tiocmget) {
		retval = tty->ops->tiocmget(tty, file);
L
Linus Torvalds 已提交
2439 2440 2441 2442 2443 2444 2445

		if (retval >= 0)
			retval = put_user(retval, p);
	}
	return retval;
}

2446
/**
A
Alan Cox 已提交
2447
 *	tty_tiocmset		-	set modem status
2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459
 *	@tty: tty device
 *	@file: user file pointer
 *	@cmd: command - clear bits, set bits or set all
 *	@p: pointer to desired bits
 *
 *	Set the modem status bits from the tty driver if the feature
 *	is supported. Return -EINVAL if it is not available.
 *
 *	Locking: none (up to the driver)
 */

static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
L
Linus Torvalds 已提交
2460 2461
	     unsigned __user *p)
{
A
Alan Cox 已提交
2462 2463
	int retval;
	unsigned int set, clear, val;
L
Linus Torvalds 已提交
2464

A
Alan Cox 已提交
2465 2466
	if (tty->ops->tiocmset == NULL)
		return -EINVAL;
L
Linus Torvalds 已提交
2467

A
Alan Cox 已提交
2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486
	retval = get_user(val, p);
	if (retval)
		return retval;
	set = clear = 0;
	switch (cmd) {
	case TIOCMBIS:
		set = val;
		break;
	case TIOCMBIC:
		clear = val;
		break;
	case TIOCMSET:
		set = val;
		clear = ~val;
		break;
	}
	set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
	clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
	return tty->ops->tiocmset(tty, file, set, clear);
L
Linus Torvalds 已提交
2487 2488 2489 2490 2491
}

/*
 * Split this up, as gcc can choke on it otherwise..
 */
A
Alan Cox 已提交
2492
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
L
Linus Torvalds 已提交
2493 2494 2495 2496 2497
{
	struct tty_struct *tty, *real_tty;
	void __user *p = (void __user *)arg;
	int retval;
	struct tty_ldisc *ld;
A
Alan Cox 已提交
2498
	struct inode *inode = file->f_dentry->d_inode;
2499

L
Linus Torvalds 已提交
2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517
	tty = (struct tty_struct *)file->private_data;
	if (tty_paranoia_check(tty, inode, "tty_ioctl"))
		return -EINVAL;

	real_tty = tty;
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_MASTER)
		real_tty = tty->link;


	/*
	 * Factor out some common prep work
	 */
	switch (cmd) {
	case TIOCSETD:
	case TIOCSBRK:
	case TIOCCBRK:
	case TCSBRK:
2518
	case TCSBRKP:
L
Linus Torvalds 已提交
2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529
		retval = tty_check_change(tty);
		if (retval)
			return retval;
		if (cmd != TIOCCBRK) {
			tty_wait_until_sent(tty, 0);
			if (signal_pending(current))
				return -EINTR;
		}
		break;
	}

A
Alan Cox 已提交
2530 2531 2532
	/*
	 *	Now do the stuff.
	 */
L
Linus Torvalds 已提交
2533
	switch (cmd) {
2534 2535 2536
	case TIOCSTI:
		return tiocsti(tty, p);
	case TIOCGWINSZ:
2537
		return tiocgwinsz(real_tty, p);
2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563
	case TIOCSWINSZ:
		return tiocswinsz(tty, real_tty, p);
	case TIOCCONS:
		return real_tty != tty ? -EINVAL : tioccons(file);
	case FIONBIO:
		return fionbio(file, p);
	case TIOCEXCL:
		set_bit(TTY_EXCLUSIVE, &tty->flags);
		return 0;
	case TIOCNXCL:
		clear_bit(TTY_EXCLUSIVE, &tty->flags);
		return 0;
	case TIOCNOTTY:
		if (current->signal->tty != tty)
			return -ENOTTY;
		no_tty();
		return 0;
	case TIOCSCTTY:
		return tiocsctty(tty, arg);
	case TIOCGPGRP:
		return tiocgpgrp(tty, real_tty, p);
	case TIOCSPGRP:
		return tiocspgrp(tty, real_tty, p);
	case TIOCGSID:
		return tiocgsid(tty, real_tty, p);
	case TIOCGETD:
A
Alan Cox 已提交
2564
		return put_user(tty->ldisc.ops->num, (int __user *)p);
2565 2566 2567 2568 2569 2570
	case TIOCSETD:
		return tiocsetd(tty, p);
	/*
	 * Break handling
	 */
	case TIOCSBRK:	/* Turn break on, unconditionally */
A
Alan Cox 已提交
2571
		if (tty->ops->break_ctl)
A
Alan Cox 已提交
2572
			return tty->ops->break_ctl(tty, -1);
2573 2574
		return 0;
	case TIOCCBRK:	/* Turn break off, unconditionally */
A
Alan Cox 已提交
2575
		if (tty->ops->break_ctl)
A
Alan Cox 已提交
2576
			return tty->ops->break_ctl(tty, 0);
2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600
		return 0;
	case TCSBRK:   /* SVID version: non-zero arg --> no break */
		/* non-zero arg means wait for all output data
		 * to be sent (performed above) but don't send break.
		 * This is used by the tcdrain() termios function.
		 */
		if (!arg)
			return send_break(tty, 250);
		return 0;
	case TCSBRKP:	/* support for POSIX tcsendbreak() */
		return send_break(tty, arg ? arg*100 : 250);

	case TIOCMGET:
		return tty_tiocmget(tty, file, p);
	case TIOCMSET:
	case TIOCMBIC:
	case TIOCMBIS:
		return tty_tiocmset(tty, file, cmd, p);
	case TCFLSH:
		switch (arg) {
		case TCIFLUSH:
		case TCIOFLUSH:
		/* flush tty buffer and allow ldisc to process ioctl */
			tty_buffer_flush(tty);
2601
			break;
2602 2603
		}
		break;
L
Linus Torvalds 已提交
2604
	}
A
Alan Cox 已提交
2605 2606
	if (tty->ops->ioctl) {
		retval = (tty->ops->ioctl)(tty, file, cmd, arg);
L
Linus Torvalds 已提交
2607 2608 2609 2610 2611
		if (retval != -ENOIOCTLCMD)
			return retval;
	}
	ld = tty_ldisc_ref_wait(tty);
	retval = -EINVAL;
A
Alan Cox 已提交
2612 2613
	if (ld->ops->ioctl) {
		retval = ld->ops->ioctl(tty, file, cmd, arg);
L
Linus Torvalds 已提交
2614 2615 2616 2617 2618 2619 2620
		if (retval == -ENOIOCTLCMD)
			retval = -EINVAL;
	}
	tty_ldisc_deref(ld);
	return retval;
}

P
Paul Fulghum 已提交
2621
#ifdef CONFIG_COMPAT
2622
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
P
Paul Fulghum 已提交
2623 2624 2625 2626 2627 2628 2629 2630 2631 2632
				unsigned long arg)
{
	struct inode *inode = file->f_dentry->d_inode;
	struct tty_struct *tty = file->private_data;
	struct tty_ldisc *ld;
	int retval = -ENOIOCTLCMD;

	if (tty_paranoia_check(tty, inode, "tty_ioctl"))
		return -EINVAL;

A
Alan Cox 已提交
2633 2634
	if (tty->ops->compat_ioctl) {
		retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
P
Paul Fulghum 已提交
2635 2636 2637 2638 2639
		if (retval != -ENOIOCTLCMD)
			return retval;
	}

	ld = tty_ldisc_ref_wait(tty);
A
Alan Cox 已提交
2640 2641
	if (ld->ops->compat_ioctl)
		retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
P
Paul Fulghum 已提交
2642 2643 2644 2645 2646
	tty_ldisc_deref(ld);

	return retval;
}
#endif
L
Linus Torvalds 已提交
2647 2648 2649 2650 2651 2652

/*
 * This implements the "Secure Attention Key" ---  the idea is to
 * prevent trojan horses by killing all processes associated with this
 * tty when the user hits the "Secure Attention Key".  Required for
 * super-paranoid applications --- see the Orange Book for more details.
2653
 *
L
Linus Torvalds 已提交
2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666
 * This code could be nicer; ideally it should send a HUP, wait a few
 * seconds, then send a INT, and then a KILL signal.  But you then
 * have to coordinate with the init process, since all processes associated
 * with the current tty must be dead before the new getty is allowed
 * to spawn.
 *
 * Now, if it would be correct ;-/ The current code has a nasty hole -
 * it doesn't catch files in flight. We may send the descriptor to ourselves
 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
 *
 * Nasty bug: do_SAK is being called in interrupt context.  This can
 * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
 */
2667
void __do_SAK(struct tty_struct *tty)
L
Linus Torvalds 已提交
2668 2669 2670 2671
{
#ifdef TTY_SOFT_SAK
	tty_hangup(tty);
#else
2672
	struct task_struct *g, *p;
2673
	struct pid *session;
L
Linus Torvalds 已提交
2674 2675
	int		i;
	struct file	*filp;
2676
	struct fdtable *fdt;
2677

L
Linus Torvalds 已提交
2678 2679
	if (!tty)
		return;
2680
	session = tty->session;
2681

2682
	tty_ldisc_flush(tty);
L
Linus Torvalds 已提交
2683

A
Alan Cox 已提交
2684
	tty_driver_flush_buffer(tty);
2685

L
Linus Torvalds 已提交
2686
	read_lock(&tasklist_lock);
2687
	/* Kill the entire session */
2688
	do_each_pid_task(session, PIDTYPE_SID, p) {
2689
		printk(KERN_NOTICE "SAK: killed process %d"
P
Pavel Emelianov 已提交
2690
			" (%s): task_session_nr(p)==tty->session\n",
2691
			task_pid_nr(p), p->comm);
2692
		send_sig(SIGKILL, p, 1);
2693
	} while_each_pid_task(session, PIDTYPE_SID, p);
2694 2695 2696 2697 2698
	/* Now kill any processes that happen to have the
	 * tty open.
	 */
	do_each_thread(g, p) {
		if (p->signal->tty == tty) {
L
Linus Torvalds 已提交
2699
			printk(KERN_NOTICE "SAK: killed process %d"
P
Pavel Emelianov 已提交
2700
			    " (%s): task_session_nr(p)==tty->session\n",
2701
			    task_pid_nr(p), p->comm);
L
Linus Torvalds 已提交
2702 2703 2704 2705 2706
			send_sig(SIGKILL, p, 1);
			continue;
		}
		task_lock(p);
		if (p->files) {
2707 2708 2709 2710 2711
			/*
			 * We don't take a ref to the file, so we must
			 * hold ->file_lock instead.
			 */
			spin_lock(&p->files->file_lock);
2712
			fdt = files_fdtable(p->files);
2713
			for (i = 0; i < fdt->max_fds; i++) {
L
Linus Torvalds 已提交
2714 2715 2716 2717 2718 2719 2720
				filp = fcheck_files(p->files, i);
				if (!filp)
					continue;
				if (filp->f_op->read == tty_read &&
				    filp->private_data == tty) {
					printk(KERN_NOTICE "SAK: killed process %d"
					    " (%s): fd#%d opened to the tty\n",
2721
					    task_pid_nr(p), p->comm, i);
2722
					force_sig(SIGKILL, p);
L
Linus Torvalds 已提交
2723 2724 2725
					break;
				}
			}
2726
			spin_unlock(&p->files->file_lock);
L
Linus Torvalds 已提交
2727 2728
		}
		task_unlock(p);
2729
	} while_each_thread(g, p);
L
Linus Torvalds 已提交
2730 2731 2732 2733
	read_unlock(&tasklist_lock);
#endif
}

2734 2735 2736 2737 2738 2739 2740
static void do_SAK_work(struct work_struct *work)
{
	struct tty_struct *tty =
		container_of(work, struct tty_struct, SAK_work);
	__do_SAK(tty);
}

L
Linus Torvalds 已提交
2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755
/*
 * The tq handling here is a little racy - tty->SAK_work may already be queued.
 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
 * the values which we write to it will be identical to the values which it
 * already has. --akpm
 */
void do_SAK(struct tty_struct *tty)
{
	if (!tty)
		return;
	schedule_work(&tty->SAK_work);
}

EXPORT_SYMBOL(do_SAK);

2756 2757 2758 2759 2760 2761 2762 2763
/**
 *	initialize_tty_struct
 *	@tty: tty to initialize
 *
 *	This subroutine initializes a tty structure that has been newly
 *	allocated.
 *
 *	Locking: none - tty in question must not be exposed at this point
L
Linus Torvalds 已提交
2764
 */
2765

2766 2767
void initialize_tty_struct(struct tty_struct *tty,
		struct tty_driver *driver, int idx)
L
Linus Torvalds 已提交
2768 2769
{
	memset(tty, 0, sizeof(struct tty_struct));
A
Alan Cox 已提交
2770
	kref_init(&tty->kref);
L
Linus Torvalds 已提交
2771
	tty->magic = TTY_MAGIC;
2772
	tty_ldisc_init(tty);
2773 2774
	tty->session = NULL;
	tty->pgrp = NULL;
L
Linus Torvalds 已提交
2775
	tty->overrun_time = jiffies;
A
Alan Cox 已提交
2776 2777
	tty->buf.head = tty->buf.tail = NULL;
	tty_buffer_init(tty);
2778
	mutex_init(&tty->termios_mutex);
L
Linus Torvalds 已提交
2779 2780
	init_waitqueue_head(&tty->write_wait);
	init_waitqueue_head(&tty->read_wait);
2781
	INIT_WORK(&tty->hangup_work, do_tty_hangup);
I
Ingo Molnar 已提交
2782 2783
	mutex_init(&tty->atomic_read_lock);
	mutex_init(&tty->atomic_write_lock);
L
Linus Torvalds 已提交
2784
	spin_lock_init(&tty->read_lock);
A
Alan Cox 已提交
2785
	spin_lock_init(&tty->ctrl_lock);
L
Linus Torvalds 已提交
2786
	INIT_LIST_HEAD(&tty->tty_files);
2787
	INIT_WORK(&tty->SAK_work, do_SAK_work);
2788 2789 2790 2791 2792

	tty->driver = driver;
	tty->ops = driver->ops;
	tty->index = idx;
	tty_line_name(driver, idx, tty->name);
L
Linus Torvalds 已提交
2793 2794
}

A
Alan Cox 已提交
2795 2796 2797 2798 2799 2800 2801 2802 2803 2804
/**
 *	tty_put_char	-	write one character to a tty
 *	@tty: tty
 *	@ch: character
 *
 *	Write one byte to the tty using the provided put_char method
 *	if present. Returns the number of characters successfully output.
 *
 *	Note: the specific put_char operation in the driver layer may go
 *	away soon. Don't call it directly, use this method
L
Linus Torvalds 已提交
2805
 */
2806

A
Alan Cox 已提交
2807
int tty_put_char(struct tty_struct *tty, unsigned char ch)
L
Linus Torvalds 已提交
2808
{
A
Alan Cox 已提交
2809 2810 2811
	if (tty->ops->put_char)
		return tty->ops->put_char(tty, ch);
	return tty->ops->write(tty, &ch, 1);
L
Linus Torvalds 已提交
2812
}
A
Alan Cox 已提交
2813 2814
EXPORT_SYMBOL_GPL(tty_put_char);

2815
struct class *tty_class;
L
Linus Torvalds 已提交
2816 2817

/**
2818 2819 2820 2821 2822 2823
 *	tty_register_device - register a tty device
 *	@driver: the tty driver that describes the tty device
 *	@index: the index in the tty driver for this tty device
 *	@device: a struct device that is associated with this tty device.
 *		This field is optional, if there is no known struct device
 *		for this tty device it can be set to NULL safely.
L
Linus Torvalds 已提交
2824
 *
2825 2826
 *	Returns a pointer to the struct device for this tty device
 *	(or ERR_PTR(-EFOO) on error).
2827
 *
2828 2829 2830 2831 2832 2833
 *	This call is required to be made to register an individual tty device
 *	if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
 *	that bit is not set, this function should not be called by a tty
 *	driver.
 *
 *	Locking: ??
L
Linus Torvalds 已提交
2834
 */
2835

2836 2837
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
				   struct device *device)
L
Linus Torvalds 已提交
2838 2839 2840 2841 2842 2843 2844
{
	char name[64];
	dev_t dev = MKDEV(driver->major, driver->minor_start) + index;

	if (index >= driver->num) {
		printk(KERN_ERR "Attempt to register invalid tty line number "
		       " (%d).\n", index);
2845
		return ERR_PTR(-EINVAL);
L
Linus Torvalds 已提交
2846 2847 2848 2849 2850 2851
	}

	if (driver->type == TTY_DRIVER_TYPE_PTY)
		pty_line_name(driver, index, name);
	else
		tty_line_name(driver, index, name);
2852

2853
	return device_create_drvdata(tty_class, device, dev, NULL, name);
L
Linus Torvalds 已提交
2854
}
A
Alan Cox 已提交
2855
EXPORT_SYMBOL(tty_register_device);
L
Linus Torvalds 已提交
2856 2857

/**
2858 2859 2860
 * 	tty_unregister_device - unregister a tty device
 * 	@driver: the tty driver that describes the tty device
 * 	@index: the index in the tty driver for this tty device
L
Linus Torvalds 已提交
2861
 *
2862 2863 2864 2865
 * 	If a tty device is registered with a call to tty_register_device() then
 *	this function must be called when the tty device is gone.
 *
 *	Locking: ??
L
Linus Torvalds 已提交
2866
 */
2867

L
Linus Torvalds 已提交
2868 2869
void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
2870 2871
	device_destroy(tty_class,
		MKDEV(driver->major, driver->minor_start) + index);
L
Linus Torvalds 已提交
2872 2873 2874 2875 2876 2877 2878
}
EXPORT_SYMBOL(tty_unregister_device);

struct tty_driver *alloc_tty_driver(int lines)
{
	struct tty_driver *driver;

J
Jean Delvare 已提交
2879
	driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
L
Linus Torvalds 已提交
2880
	if (driver) {
A
Alan Cox 已提交
2881
		kref_init(&driver->kref);
L
Linus Torvalds 已提交
2882 2883 2884 2885 2886 2887
		driver->magic = TTY_DRIVER_MAGIC;
		driver->num = lines;
		/* later we'll move allocation of tables here */
	}
	return driver;
}
A
Alan Cox 已提交
2888
EXPORT_SYMBOL(alloc_tty_driver);
L
Linus Torvalds 已提交
2889

A
Alan Cox 已提交
2890
static void destruct_tty_driver(struct kref *kref)
L
Linus Torvalds 已提交
2891
{
A
Alan Cox 已提交
2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914
	struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
	int i;
	struct ktermios *tp;
	void *p;

	if (driver->flags & TTY_DRIVER_INSTALLED) {
		/*
		 * Free the termios and termios_locked structures because
		 * we don't want to get memory leaks when modular tty
		 * drivers are removed from the kernel.
		 */
		for (i = 0; i < driver->num; i++) {
			tp = driver->termios[i];
			if (tp) {
				driver->termios[i] = NULL;
				kfree(tp);
			}
			if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
				tty_unregister_device(driver, i);
		}
		p = driver->ttys;
		proc_tty_unregister_driver(driver);
		driver->ttys = NULL;
A
Alan Cox 已提交
2915
		driver->termios = NULL;
A
Alan Cox 已提交
2916 2917 2918
		kfree(p);
		cdev_del(&driver->cdev);
	}
L
Linus Torvalds 已提交
2919 2920 2921
	kfree(driver);
}

A
Alan Cox 已提交
2922 2923 2924 2925 2926 2927
void tty_driver_kref_put(struct tty_driver *driver)
{
	kref_put(&driver->kref, destruct_tty_driver);
}
EXPORT_SYMBOL(tty_driver_kref_put);

J
Jeff Dike 已提交
2928 2929
void tty_set_operations(struct tty_driver *driver,
			const struct tty_operations *op)
L
Linus Torvalds 已提交
2930
{
A
Alan Cox 已提交
2931 2932
	driver->ops = op;
};
A
Alan Cox 已提交
2933
EXPORT_SYMBOL(tty_set_operations);
L
Linus Torvalds 已提交
2934

A
Alan Cox 已提交
2935 2936 2937 2938
void put_tty_driver(struct tty_driver *d)
{
	tty_driver_kref_put(d);
}
L
Linus Torvalds 已提交
2939 2940 2941 2942 2943 2944 2945 2946
EXPORT_SYMBOL(put_tty_driver);

/*
 * Called by a tty driver to register itself.
 */
int tty_register_driver(struct tty_driver *driver)
{
	int error;
2947
	int i;
L
Linus Torvalds 已提交
2948 2949 2950
	dev_t dev;
	void **p = NULL;

2951
	if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
A
Alan Cox 已提交
2952
		p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
L
Linus Torvalds 已提交
2953 2954 2955 2956 2957
		if (!p)
			return -ENOMEM;
	}

	if (!driver->major) {
2958 2959
		error = alloc_chrdev_region(&dev, driver->minor_start,
						driver->num, driver->name);
L
Linus Torvalds 已提交
2960 2961 2962 2963 2964 2965
		if (!error) {
			driver->major = MAJOR(dev);
			driver->minor_start = MINOR(dev);
		}
	} else {
		dev = MKDEV(driver->major, driver->minor_start);
2966
		error = register_chrdev_region(dev, driver->num, driver->name);
L
Linus Torvalds 已提交
2967 2968 2969 2970 2971 2972 2973 2974
	}
	if (error < 0) {
		kfree(p);
		return error;
	}

	if (p) {
		driver->ttys = (struct tty_struct **)p;
2975
		driver->termios = (struct ktermios **)(p + driver->num);
L
Linus Torvalds 已提交
2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986
	} else {
		driver->ttys = NULL;
		driver->termios = NULL;
	}

	cdev_init(&driver->cdev, &tty_fops);
	driver->cdev.owner = driver->owner;
	error = cdev_add(&driver->cdev, dev, driver->num);
	if (error) {
		unregister_chrdev_region(dev, driver->num);
		driver->ttys = NULL;
A
Alan Cox 已提交
2987
		driver->termios = NULL;
L
Linus Torvalds 已提交
2988 2989 2990 2991
		kfree(p);
		return error;
	}

2992
	mutex_lock(&tty_mutex);
L
Linus Torvalds 已提交
2993
	list_add(&driver->tty_drivers, &tty_drivers);
2994
	mutex_unlock(&tty_mutex);
2995 2996 2997

	if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
		for (i = 0; i < driver->num; i++)
L
Linus Torvalds 已提交
2998 2999 3000
		    tty_register_device(driver, i, NULL);
	}
	proc_tty_register_driver(driver);
A
Alan Cox 已提交
3001
	driver->flags |= TTY_DRIVER_INSTALLED;
L
Linus Torvalds 已提交
3002 3003 3004 3005 3006 3007 3008 3009 3010 3011
	return 0;
}

EXPORT_SYMBOL(tty_register_driver);

/*
 * Called by a tty driver to unregister itself.
 */
int tty_unregister_driver(struct tty_driver *driver)
{
A
Alan Cox 已提交
3012 3013
#if 0
	/* FIXME */
L
Linus Torvalds 已提交
3014 3015
	if (driver->refcount)
		return -EBUSY;
A
Alan Cox 已提交
3016
#endif
L
Linus Torvalds 已提交
3017 3018
	unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
				driver->num);
3019
	mutex_lock(&tty_mutex);
L
Linus Torvalds 已提交
3020
	list_del(&driver->tty_drivers);
3021
	mutex_unlock(&tty_mutex);
L
Linus Torvalds 已提交
3022 3023
	return 0;
}
A
Alan Cox 已提交
3024

L
Linus Torvalds 已提交
3025 3026
EXPORT_SYMBOL(tty_unregister_driver);

3027 3028 3029 3030 3031 3032 3033 3034
dev_t tty_devnum(struct tty_struct *tty)
{
	return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}
EXPORT_SYMBOL(tty_devnum);

void proc_clear_tty(struct task_struct *p)
{
3035
	unsigned long flags;
A
Alan Cox 已提交
3036
	struct tty_struct *tty;
3037
	spin_lock_irqsave(&p->sighand->siglock, flags);
A
Alan Cox 已提交
3038
	tty = p->signal->tty;
3039
	p->signal->tty = NULL;
3040
	spin_unlock_irqrestore(&p->sighand->siglock, flags);
A
Alan Cox 已提交
3041
	tty_kref_put(tty);
3042 3043
}

A
Alan Cox 已提交
3044 3045
/* Called under the sighand lock */

3046
static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3047 3048
{
	if (tty) {
A
Alan Cox 已提交
3049 3050 3051
		unsigned long flags;
		/* We should not have a session or pgrp to put here but.... */
		spin_lock_irqsave(&tty->ctrl_lock, flags);
3052 3053
		put_pid(tty->session);
		put_pid(tty->pgrp);
3054
		tty->pgrp = get_pid(task_pgrp(tsk));
A
Alan Cox 已提交
3055 3056
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		tty->session = get_pid(task_session(tsk));
A
Alan Cox 已提交
3057 3058 3059 3060
		if (tsk->signal->tty) {
			printk(KERN_DEBUG "tty not NULL!!\n");
			tty_kref_put(tsk->signal->tty);
		}
3061
	}
3062
	put_pid(tsk->signal->tty_old_pgrp);
A
Alan Cox 已提交
3063
	tsk->signal->tty = tty_kref_get(tty);
3064
	tsk->signal->tty_old_pgrp = NULL;
3065 3066
}

3067
static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3068 3069
{
	spin_lock_irq(&tsk->sighand->siglock);
3070
	__proc_set_tty(tsk, tty);
3071 3072 3073 3074 3075 3076
	spin_unlock_irq(&tsk->sighand->siglock);
}

struct tty_struct *get_current_tty(void)
{
	struct tty_struct *tty;
A
Alan Cox 已提交
3077 3078 3079
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
A
Alan Cox 已提交
3080
	tty = tty_kref_get(current->signal->tty);
A
Alan Cox 已提交
3081
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
3082 3083
	return tty;
}
3084
EXPORT_SYMBOL_GPL(get_current_tty);
L
Linus Torvalds 已提交
3085

3086 3087 3088 3089 3090
void tty_default_fops(struct file_operations *fops)
{
	*fops = tty_fops;
}

L
Linus Torvalds 已提交
3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101
/*
 * Initialize the console device. This is called *early*, so
 * we can't necessarily depend on lots of kernel help here.
 * Just do some early initializations, and do the complex setup
 * later.
 */
void __init console_init(void)
{
	initcall_t *call;

	/* Setup the default TTY line discipline. */
3102
	tty_ldisc_begin();
L
Linus Torvalds 已提交
3103 3104

	/*
3105
	 * set up the console device so that later boot sequences can
L
Linus Torvalds 已提交
3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116
	 * inform about problems etc..
	 */
	call = __con_initcall_start;
	while (call < __con_initcall_end) {
		(*call)();
		call++;
	}
}

static int __init tty_class_init(void)
{
3117
	tty_class = class_create(THIS_MODULE, "tty");
L
Linus Torvalds 已提交
3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138
	if (IS_ERR(tty_class))
		return PTR_ERR(tty_class);
	return 0;
}

postcore_initcall(tty_class_init);

/* 3/2004 jmc: why do these devices exist? */

static struct cdev tty_cdev, console_cdev;

/*
 * Ok, now we can initialize the rest of the tty devices and can count
 * on memory allocations, interrupts etc..
 */
static int __init tty_init(void)
{
	cdev_init(&tty_cdev, &tty_fops);
	if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
		panic("Couldn't register /dev/tty driver\n");
3139
	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3140
			      "tty");
L
Linus Torvalds 已提交
3141 3142 3143 3144 3145

	cdev_init(&console_cdev, &console_fops);
	if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
		panic("Couldn't register /dev/console driver\n");
3146
	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3147
			      "console");
L
Linus Torvalds 已提交
3148 3149

#ifdef CONFIG_VT
3150
	vty_init(&console_fops);
L
Linus Torvalds 已提交
3151 3152 3153 3154
#endif
	return 0;
}
module_init(tty_init);