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Replace select backends with poll backends.  selscan() and pollscan()
now call the poll backend.  With this change we implement greater
poll(2) functionality instead of emulating it via the select backend.
Adapted from NetBSD and including some changes from FreeBSD.
Tested by many, deraadt@ OK

/*	$OpenBSD: tty_tty.c,v 1.8 2003/09/23 16:51:12 millert Exp $	*/
/*	$NetBSD: tty_tty.c,v 1.13 1996/03/30 22:24:46 christos Exp $	*/

/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 *	@(#)tty_tty.c	8.2 (Berkeley) 9/23/93
 */

/*
 * Indirect driver for controlling tty.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/conf.h>


#define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)

/*ARGSUSED*/
int
cttyopen(dev, flag, mode, p)
	dev_t dev;
	int flag, mode;
	struct proc *p;
{
	struct vnode *ttyvp = cttyvp(p);
	int error;

	if (ttyvp == NULL)
		return (ENXIO);
	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
#ifdef PARANOID
	/*
	 * Since group is tty and mode is 620 on most terminal lines
	 * and since sessions protect terminals from processes outside
	 * your session, this check is probably no longer necessary.
	 * Since it inhibits setuid root programs that later switch 
	 * to another user from accessing /dev/tty, we have decided
	 * to delete this test. (mckusick 5/93)
	 */
	error = VOP_ACCESS(ttyvp,
	  (flag&FREAD ? VREAD : 0) | (flag&FWRITE ? VWRITE : 0), p->p_ucred, p);
	if (!error)
#endif /* PARANOID */
		error = VOP_OPEN(ttyvp, flag, NOCRED, p);
	VOP_UNLOCK(ttyvp, 0, p);
	return (error);
}

/*ARGSUSED*/
int
cttyread(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	struct proc *p = uio->uio_procp;
	register struct vnode *ttyvp = cttyvp(uio->uio_procp);
	int error;

	if (ttyvp == NULL)
		return (EIO);
	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
	error = VOP_READ(ttyvp, uio, flag, NOCRED);
	VOP_UNLOCK(ttyvp, 0, p);
	return (error);
}

/*ARGSUSED*/
int
cttywrite(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	struct proc *p = uio->uio_procp;
	register struct vnode *ttyvp = cttyvp(uio->uio_procp);
	int error;

	if (ttyvp == NULL)
		return (EIO);
	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
	error = VOP_WRITE(ttyvp, uio, flag, NOCRED);
	VOP_UNLOCK(ttyvp, 0, p);
	return (error);
}

/*ARGSUSED*/
int
cttyioctl(dev, cmd, addr, flag, p)
	dev_t dev;
	u_long cmd;
	caddr_t addr;
	int flag;
	struct proc *p;
{
	struct vnode *ttyvp = cttyvp(p);

	if (ttyvp == NULL)
		return (EIO);
	if (cmd == TIOCSCTTY)		/* XXX */
		return (EINVAL);
	if (cmd == TIOCNOTTY) {
		if (!SESS_LEADER(p)) {
			p->p_flag &= ~P_CONTROLT;
			return (0);
		} else
			return (EINVAL);
	}
	return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED, p));
}

/*ARGSUSED*/
int
cttypoll(dev, events, p)
	dev_t dev;
	int events;
	struct proc *p;
{
	struct vnode *ttyvp = cttyvp(p);

	if (ttyvp == NULL)	/* try operation to get EOF/failure */
		return (seltrue(dev, events, p));
	return (VOP_POLL(ttyvp, events, p));
}