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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: vfs_vnops.c,v 1.44 2003/09/23 16:51:12 millert Exp $	*/
/*	$NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 *
 *	@(#)vfs_vnops.c	8.5 (Berkeley) 12/8/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/cdio.h>
#include <sys/poll.h>

#include <uvm/uvm_extern.h>

int	vn_read(struct file *fp, off_t *off, struct uio *uio, 
	    struct ucred *cred);
int	vn_write(struct file *fp, off_t *off, struct uio *uio, 
	    struct ucred *cred);
int	vn_poll(struct file *fp, int events, struct proc *p);
int	vn_kqfilter(struct file *fp, struct knote *kn);
int 	vn_closefile(struct file *fp, struct proc *p);
int	vn_ioctl(struct file *fp, u_long com, caddr_t data,
	    struct proc *p);

struct 	fileops vnops =
	{ vn_read, vn_write, vn_ioctl, vn_poll, vn_kqfilter, vn_statfile,
	  vn_closefile };

/*
 * Common code for vnode open operations.
 * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
 */
int
vn_open(ndp, fmode, cmode)
	register struct nameidata *ndp;
	int fmode, cmode;
{
	register struct vnode *vp;
	register struct proc *p = ndp->ni_cnd.cn_proc;
	register struct ucred *cred = p->p_ucred;
	struct vattr va;
	int error;

	if ((fmode & (FREAD|FWRITE)) == 0)
		return (EINVAL);
	if ((fmode & (O_TRUNC | FWRITE)) == O_TRUNC)
		return (EINVAL);
	if (fmode & O_CREAT) {
		ndp->ni_cnd.cn_nameiop = CREATE;
		ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
		if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
			ndp->ni_cnd.cn_flags |= FOLLOW;
		if ((error = namei(ndp)) != 0)
			return (error);

		if (ndp->ni_vp == NULL) {
			VATTR_NULL(&va);
			va.va_type = VREG;
			va.va_mode = cmode;
			VOP_LEASE(ndp->ni_dvp, p, cred, LEASE_WRITE);
			error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
					   &ndp->ni_cnd, &va);
			if (error)
				return (error);
			fmode &= ~O_TRUNC;
			vp = ndp->ni_vp;
		} else {
			VOP_ABORTOP(ndp->ni_dvp, &ndp->ni_cnd);
			if (ndp->ni_dvp == ndp->ni_vp)
				vrele(ndp->ni_dvp);
			else
				vput(ndp->ni_dvp);
			ndp->ni_dvp = NULL;
			vp = ndp->ni_vp;
			if (fmode & O_EXCL) {
				error = EEXIST;
				goto bad;
			}
			fmode &= ~O_CREAT;
		}
	} else {
		ndp->ni_cnd.cn_nameiop = LOOKUP;
		ndp->ni_cnd.cn_flags =
		    ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
		if ((error = namei(ndp)) != 0)
			return (error);
		vp = ndp->ni_vp;
	}
	if (vp->v_type == VSOCK) {
		error = EOPNOTSUPP;
		goto bad;
	}
	if (vp->v_type == VLNK) {
		error = EMLINK;
		goto bad;
	}
	if ((fmode & O_CREAT) == 0) {
		if (fmode & FREAD) {
			if ((error = VOP_ACCESS(vp, VREAD, cred, p)) != 0)
				goto bad;
		}
		if (fmode & FWRITE) {
			if (vp->v_type == VDIR) {
				error = EISDIR;
				goto bad;
			}
			if ((error = vn_writechk(vp)) != 0 ||
			    (error = VOP_ACCESS(vp, VWRITE, cred, p)) != 0)
				goto bad;
		}
	}
	if ((fmode & O_TRUNC) && vp->v_type == VREG) {
		VOP_UNLOCK(vp, 0, p);				/* XXX */
		VOP_LEASE(vp, p, cred, LEASE_WRITE);
		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);	/* XXX */
		VATTR_NULL(&va);
		va.va_size = 0;
		if ((error = VOP_SETATTR(vp, &va, cred, p)) != 0)
			goto bad;
	}
	if ((error = VOP_OPEN(vp, fmode, cred, p)) != 0)
		goto bad;
	if (fmode & FWRITE)
		vp->v_writecount++;
	return (0);
bad:
	vput(vp);
	return (error);
}

/*
 * Check for write permissions on the specified vnode.
 * Prototype text segments cannot be written.
 */
int
vn_writechk(vp)
	register struct vnode *vp;
{

	/*
	 * Disallow write attempts on read-only file systems;
	 * unless the file is a socket or a block or character
	 * device resident on the file system.
	 */
	if (vp->v_mount->mnt_flag & MNT_RDONLY) {
		switch (vp->v_type) {
		case VREG: case VDIR: case VLNK:
			return (EROFS);
		case VNON: case VCHR: case VSOCK:
		case VFIFO: case VBAD: case VBLK:
			break;
		}
	}
	/*
	 * If there's shared text associated with
	 * the vnode, try to free it up once.  If
	 * we fail, we can't allow writing.
	 */
	if ((vp->v_flag & VTEXT) && !uvm_vnp_uncache(vp))
		return (ETXTBSY);

	return (0);
}

/*
 * Mark a vnode as being the text image of a running process.
 */
void
vn_marktext(vp)
	struct vnode *vp;
{
	vp->v_flag |= VTEXT;
}

/*
 * Vnode close call
 */
int
vn_close(vp, flags, cred, p)
	register struct vnode *vp;
	int flags;
	struct ucred *cred;
	struct proc *p;
{
	int error;

	if (flags & FWRITE)
		vp->v_writecount--;
	error = VOP_CLOSE(vp, flags, cred, p);
	vrele(vp);
	return (error);
}

/*
 * Package up an I/O request on a vnode into a uio and do it.
 */
int
vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid, p)
	enum uio_rw rw;
	struct vnode *vp;
	caddr_t base;
	int len;
	off_t offset;
	enum uio_seg segflg;
	int ioflg;
	struct ucred *cred;
	size_t *aresid;
	struct proc *p;
{
	struct uio auio;
	struct iovec aiov;
	int error;

	if ((ioflg & IO_NODELOCKED) == 0)
		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	aiov.iov_base = base;
	aiov.iov_len = len;
	auio.uio_resid = len;
	auio.uio_offset = offset;
	auio.uio_segflg = segflg;
	auio.uio_rw = rw;
	auio.uio_procp = p;
	if (rw == UIO_READ) {
		error = VOP_READ(vp, &auio, ioflg, cred);
	} else {
		error = VOP_WRITE(vp, &auio, ioflg, cred);
	}
	if (aresid)
		*aresid = auio.uio_resid;
	else
		if (auio.uio_resid && error == 0)
			error = EIO;
	if ((ioflg & IO_NODELOCKED) == 0)
		VOP_UNLOCK(vp, 0, p);
	return (error);
}

/*
 * File table vnode read routine.
 */
int
vn_read(fp, poff, uio, cred)
	struct file *fp;
	off_t *poff;
	struct uio *uio;
	struct ucred *cred;
{
	register struct vnode *vp = (struct vnode *)fp->f_data;
	int error = 0;
	size_t count;
	struct proc *p = uio->uio_procp;

	VOP_LEASE(vp, uio->uio_procp, cred, LEASE_READ);
	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
	uio->uio_offset = *poff;
	count = uio->uio_resid;
	if (vp->v_type != VDIR)
		error = VOP_READ(vp, uio,
		    (fp->f_flag & FNONBLOCK) ? IO_NDELAY : 0, cred);
	*poff += count - uio->uio_resid;
	VOP_UNLOCK(vp, 0, p);
	return (error);
}

/*
 * File table vnode write routine.
 */
int
vn_write(fp, poff, uio, cred)
	struct file *fp;
	off_t *poff;
	struct uio *uio;
	struct ucred *cred;
{
	register struct vnode *vp = (struct vnode *)fp->f_data;
	struct proc *p = uio->uio_procp;
	int error, ioflag = IO_UNIT;
	size_t count;

	if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
		ioflag |= IO_APPEND;
	if (fp->f_flag & FNONBLOCK)
		ioflag |= IO_NDELAY;
	if ((fp->f_flag & FFSYNC) ||
	    (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
		ioflag |= IO_SYNC;
	VOP_LEASE(vp, uio->uio_procp, cred, LEASE_WRITE);
	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
	uio->uio_offset = *poff;
	count = uio->uio_resid;
	error = VOP_WRITE(vp, uio, ioflag, cred);
	if (ioflag & IO_APPEND)
		*poff = uio->uio_offset;
	else
		*poff += count - uio->uio_resid;
	VOP_UNLOCK(vp, 0, p);
	return (error);
}

/*
 * File table wrapper for vn_stat
 */
int
vn_statfile(fp, sb, p)
	struct file *fp;
	struct stat *sb;
	struct proc *p;
{
	struct vnode *vp = (struct vnode *)fp->f_data;

	return vn_stat(vp, sb, p);
}

/*
 * vnode stat routine.
 */
int
vn_stat(vp, sb, p)
	struct vnode *vp;
	register struct stat *sb;
	struct proc *p;
{
	struct vattr va;
	int error;
	u_short mode;

	error = VOP_GETATTR(vp, &va, p->p_ucred, p);
	if (error)
		return (error);
	/*
	 * Copy from vattr table
	 */
	sb->st_dev = va.va_fsid;
	sb->st_ino = va.va_fileid;
	mode = va.va_mode;
	switch (vp->v_type) {
	case VREG:
		mode |= S_IFREG;
		break;
	case VDIR:
		mode |= S_IFDIR;
		break;
	case VBLK:
		mode |= S_IFBLK;
		break;
	case VCHR:
		mode |= S_IFCHR;
		break;
	case VLNK:
		mode |= S_IFLNK;
		break;
	case VSOCK:
		mode |= S_IFSOCK;
		break;
	case VFIFO:
		mode |= S_IFIFO;
		break;
	default:
		return (EBADF);
	}
	sb->st_mode = mode;
	sb->st_nlink = va.va_nlink;
	sb->st_uid = va.va_uid;
	sb->st_gid = va.va_gid;
	sb->st_rdev = va.va_rdev;
	sb->st_size = va.va_size;
	sb->st_atimespec = va.va_atime;
	sb->st_mtimespec = va.va_mtime;
	sb->st_ctimespec = va.va_ctime;
	sb->st_blksize = va.va_blocksize;
	sb->st_flags = va.va_flags;
	sb->st_gen = va.va_gen;
	sb->st_blocks = va.va_bytes / S_BLKSIZE;
	return (0);
}

/*
 * File table vnode ioctl routine.
 */
int
vn_ioctl(fp, com, data, p)
	struct file *fp;
	u_long com;
	caddr_t data;
	struct proc *p;
{
	register struct vnode *vp = ((struct vnode *)fp->f_data);
	struct vattr vattr;
	int error;

	switch (vp->v_type) {

	case VREG:
	case VDIR:
		if (com == FIONREAD) {
			error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);
			if (error)
				return (error);
			*(int *)data = vattr.va_size - fp->f_offset;
			return (0);
		}
		if (com == FIBMAP)
			return VOP_IOCTL(vp, com, data, fp->f_flag,
					 p->p_ucred, p);
		if (com == FIONBIO || com == FIOASYNC)  /* XXX */
			return (0);			/* XXX */
		/* fall into... */

	default:
		return (ENOTTY);
		
	case VFIFO:
	case VCHR:
	case VBLK:
		error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
		if (error == 0 && com == TIOCSCTTY) {
			if (p->p_session->s_ttyvp)
				vrele(p->p_session->s_ttyvp);
			p->p_session->s_ttyvp = vp;
			VREF(vp);
		}
		return (error);
	}
}

/*
 * File table vnode poll routine.
 */
int
vn_poll(fp, events, p)
	struct file *fp;
	int events;
	struct proc *p;
{

	return (VOP_POLL(((struct vnode *)fp->f_data), events, p));
}

/*
 * Check that the vnode is still valid, and if so
 * acquire requested lock.
 */
int
vn_lock(struct vnode *vp, int flags, struct proc *p)
{
	int error;

	if ((flags & LK_RECURSEFAIL) == 0)
		flags |= LK_CANRECURSE;
	
	do {
		if ((flags & LK_INTERLOCK) == 0)
			simple_lock(&vp->v_interlock);
		if (vp->v_flag & VXLOCK) {
			vp->v_flag |= VXWANT;
			simple_unlock(&vp->v_interlock);
			tsleep(vp, PINOD, "vn_lock", 0);
			error = ENOENT;
		} else {
			error = VOP_LOCK(vp, flags | LK_INTERLOCK, p);
			if (error == 0)
				return (error);
		}
		flags &= ~LK_INTERLOCK;
	} while (flags & LK_RETRY);
	return (error);
}

/*
 * File table vnode close routine.
 */
int
vn_closefile(fp, p)
	struct file *fp;
	struct proc *p;
{

	return (vn_close(((struct vnode *)fp->f_data), fp->f_flag,
		fp->f_cred, p));
}

/*ARGSUSED*/
int
vn_kqfilter(struct file *fp, struct knote *kn)
{
	return (VOP_KQFILTER(((struct vnode *)fp->f_data), kn));
}