openbsd-src / sys / dev / cons.c

/*	$OpenBSD: cons.c,v 1.31 2025/09/20 13:53:36 mpi Exp $	*/
/*	$NetBSD: cons.c,v 1.30 1996/04/08 19:57:30 jonathan Exp $	*/

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * from: Utah $Hdr: cons.c 1.7 92/01/21$
 *
 *	@(#)cons.c	8.2 (Berkeley) 1/12/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/conf.h>
#include <sys/vnode.h>

#include <dev/cons.h>

struct	tty *constty = NULL;		/* virtual console output device */
struct	vnode *cn_devvp = NULL;		/* vnode for underlying device. */

int
cnopen(dev_t dev, int flag, int mode, struct proc *p)
{
	dev_t cndev;

	if (cn_tab == NULL)
		return (0);

	/*
	 * always open the 'real' console device, so we don't get nailed
	 * later.  This follows normal device semantics; they always get
	 * open() calls.
	 */
	cndev = cn_tab->cn_dev;
	if (cndev == NODEV)
		return (ENXIO);
#ifdef DIAGNOSTIC
	if (cndev == dev)
		panic("cnopen: recursive");
#endif
	if (cn_devvp == NULL) {
		/* try to get a reference on its vnode, but fail silently */
		cdevvp(cndev, &cn_devvp);
	}
	return ((*cdevsw[major(cndev)].d_open)(cndev, flag, mode, p));
}
 
int
cnclose(dev_t dev, int flag, int mode, struct proc *p)
{
	struct vnode *vp;

	if (cn_tab == NULL)
		return (0);

	/*
	 * If the real console isn't otherwise open, close it.
	 * If it's otherwise open, don't close it, because that'll
	 * screw up others who have it open.
	 */
	dev = cn_tab->cn_dev;
	if (cn_devvp != NULL) {
		/* release our reference to real dev's vnode */
		vrele(cn_devvp);
		cn_devvp = NULL;
	}
	if (vfinddev(dev, VCHR, &vp) && vcount(vp))
		return (0);
	return ((*cdevsw[major(dev)].d_close)(dev, flag, mode, p));
}
 
int
cnread(dev_t dev, struct uio *uio, int flag)
{

	/*
	 * If we would redirect input, punt.  This will keep strange
	 * things from happening to people who are using the real
	 * console.  Nothing should be using /dev/console for
	 * input (except a shell in single-user mode, but then,
	 * one wouldn't TIOCCONS then).
	 */
	if (constty != NULL)
		return 0;
	else if (cn_tab == NULL)
		return ENXIO;

	dev = cn_tab->cn_dev;
	return ((*cdevsw[major(dev)].d_read)(dev, uio, flag));
}
 
int
cnwrite(dev_t dev, struct uio *uio, int flag)
{

	/*
	 * Redirect output, if that's appropriate.
	 * If there's no real console, return ENXIO.
	 */
	if (constty != NULL)
		dev = constty->t_dev;
	else if (cn_tab == NULL)
		return ENXIO;
	else
		dev = cn_tab->cn_dev;
	return ((*cdevsw[major(dev)].d_write)(dev, uio, flag));
}

int
cnstop(struct tty *tp, int flag)
{
	return (0);
}
 
int
cnioctl(dev_t dev, u_long cmd, caddr_t data, int flag,
    struct proc *p)
{
	int error;

	/*
	 * Superuser can always use this to wrest control of console
	 * output from the "virtual" console.
	 */
	if (cmd == TIOCCONS && constty != NULL) {
		error = suser(p);
		if (error)
			return (error);
		constty = NULL;
		return (0);
	}

	/*
	 * Redirect the ioctl, if that's appropriate.
	 * Note that strange things can happen, if a program does
	 * ioctls on /dev/console, then the console is redirected
	 * out from under it.
	 */
	if (constty != NULL)
		dev = constty->t_dev;
	else if (cn_tab == NULL)
		return ENXIO;
	else
		dev = cn_tab->cn_dev;
	return ((*cdevsw[major(dev)].d_ioctl)(dev, cmd, data, flag, p));
}

int
cnkqfilter(dev_t dev, struct knote *kn)
{

	/*
	 * Redirect output, if that's appropriate.
	 * If there's no real console, return 1.
	 */
	if (constty != NULL)
		dev = constty->t_dev;
	else if (cn_tab == NULL)
		return (ENXIO);
	else
		dev = cn_tab->cn_dev;
	if (cdevsw[major(dev)].d_kqfilter)
		return ((*cdevsw[major(dev)].d_kqfilter)(dev, kn));
	return (EOPNOTSUPP);
}

int
cngetc(void)
{

	if (cn_tab == NULL)
		return (0);
	return ((*cn_tab->cn_getc)(cn_tab->cn_dev));
}

void
cnputc(int c)
{

	if (cn_tab == NULL)
		return;			

	if (c) {
		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
		if (c == '\n')
			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
	}
}

void
cnpollc(int on)
{
	static int refcount = 0;

	if (cn_tab == NULL)
		return;
	if (!on)
		--refcount;
	if (refcount == 0)
		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
	if (on)
		++refcount;
}

void
nullcnpollc(dev_t dev, int on)
{

}

void
cnbell(u_int pitch, u_int period, u_int volume)
{
	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
		return;

	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
}