path: root/drivers/tty/vt/vt_ioctl.c

/*
 *  Copyright (C) 1992 obz under the linux copyright
 *
 *  Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
 *  Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
 *  Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
 *  Some code moved for less code duplication - Andi Kleen - Mar 1997
 *  Check put/get_user, cleanups - acme@conectiva.com.br - Jun 2001
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/kernel.h>
#include <linux/compat.h>
#include <linux/module.h>
#include <linux/kd.h>
#include <linux/vt.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/console.h>
#include <linux/consolemap.h>
#include <linux/signal.h>
#include <linux/timex.h>

#include <asm/io.h>
#include <asm/uaccess.h>

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

char vt_dont_switch;
extern struct tty_driver *console_driver;

#define VT_IS_IN_USE(i)	(console_driver->ttys[i] && console_driver->ttys[i]->count)
#define VT_BUSY(i)	(VT_IS_IN_USE(i) || i == fg_console || vc_cons[i].d == sel_cons)

/*
 * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
 * experimentation and study of X386 SYSV handling.
 *
 * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
 * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
 * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
 * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
 * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
 * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
 * to the current console is done by the main ioctl code.
 */

#ifdef CONFIG_X86
#include <linux/syscalls.h>
#endif

static void complete_change_console(struct vc_data *vc);

/*
 *	User space VT_EVENT handlers
 */

struct vt_event_wait {
	struct list_head list;
	struct vt_event event;
	int done;
};

static LIST_HEAD(vt_events);
static DEFINE_SPINLOCK(vt_event_lock);
static DECLARE_WAIT_QUEUE_HEAD(vt_event_waitqueue);

/**
 *	vt_event_post
 *	@event: the event that occurred
 *	@old: old console
 *	@new: new console
 *
 *	Post an VT event to interested VT handlers
 */

void vt_event_post(unsigned int event, unsigned int old, unsigned int new)
{
	struct list_head *pos, *head;
	unsigned long flags;
	int wake = 0;

	spin_lock_irqsave(&vt_event_lock, flags);
	head = &vt_events;

	list_for_each(pos, head) {
		struct vt_event_wait *ve = list_entry(pos,
						struct vt_event_wait, list);
		if (!(ve->event.event & event))
			continue;
		ve->event.event = event;
		/* kernel view is consoles 0..n-1, user space view is
		   console 1..n with 0 meaning current, so we must bias */
		ve->event.oldev = old + 1;
		ve->event.newev = new + 1;
		wake = 1;
		ve->done = 1;
	}
	spin_unlock_irqrestore(&vt_event_lock, flags);
	if (wake)
		wake_up_interruptible(&vt_event_waitqueue);
}

/**
 *	vt_event_wait		-	wait for an event
 *	@vw: our event
 *
 *	Waits for an event to occur which completes our vt_event_wait
 *	structure. On return the structure has wv->done set to 1 for success
 *	or 0 if some event such as a signal ended the wait.
 */

static void vt_event_wait(struct vt_event_wait *vw)
{
	unsigned long flags;
	/* Prepare the event */
	INIT_LIST_HEAD(&vw->list);
	vw->done = 0;
	/* Queue our event */
	spin_lock_irqsave(&vt_event_lock, flags);
	list_add(&vw->list, &vt_events);
	spin_unlock_irqrestore(&vt_event_lock, flags);
	/* Wait for it to pass */
	wait_event_interruptible(vt_event_waitqueue, vw->done);
	/* Dequeue it */
	spin_lock_irqsave(&vt_event_lock, flags);
	list_del(&vw->list);
	spin_unlock_irqrestore(&vt_event_lock, flags);
}

/**
 *	vt_event_wait_ioctl	-	event ioctl handler
 *	@arg: argument to ioctl
 *
 *	Implement the VT_WAITEVENT ioctl using the VT event interface
 */

static int vt_event_wait_ioctl