xref: /src/sys/kern/vfs_syscalls.c

/*	$NetBSD: vfs_syscalls.c,v 1.110 1998/02/05 08:00:05 mrg Exp $	*/

/*
 * Copyright (c) 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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_syscalls.c	8.28 (Berkeley) 12/10/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/dirent.h>

#include <sys/syscallargs.h>

#include <vm/vm.h>
#include <sys/sysctl.h>

#if defined(UVM)
#include <uvm/uvm_extern.h>
#endif

static int change_dir __P((struct nameidata *, struct proc *));
static int change_mode __P((struct vnode *, int, struct proc *p));
static int change_owner __P((struct vnode *, uid_t, gid_t, struct proc *));
static int change_utimes __P((struct vnode *vp, const struct timeval *,
	       struct proc *p));
static int rename_files __P((const char *, const char *, struct proc *, int));

void checkdirs __P((struct vnode *));
int dounmount __P((struct mount *, int, struct proc *));

/*
 * Virtual File System System Calls
 */

/*
 * Mount a file system.
 */

#if defined(COMPAT_09) || defined(COMPAT_43)
/*
 * This table is used to maintain compatibility with 4.3BSD
 * and NetBSD 0.9 mount syscalls.  Note, the order is important!
 */
static const char *mountcompatnames[] = {
	NULL,		/* 0 = MOUNT_NONE */
	MOUNT_FFS,	/* 1 */
	MOUNT_NFS,	/* 2 */
	MOUNT_MFS,	/* 3 */
	MOUNT_MSDOS,	/* 4 */
	MOUNT_LFS,	/* 5 */
	NULL,		/* 6 = MOUNT_LOFS */
	MOUNT_FDESC,	/* 7 */
	MOUNT_PORTAL,	/* 8 */
	MOUNT_NULL,	/* 9 */
	MOUNT_UMAP,	/* 10 */
	MOUNT_KERNFS,	/* 11 */
	MOUNT_PROCFS,	/* 12 */
	MOUNT_AFS,	/* 13 */
	MOUNT_CD9660,	/* 14 = MOUNT_ISOFS */
	MOUNT_UNION,	/* 15 */
	MOUNT_ADOSFS,	/* 16 */
	MOUNT_EXT2FS,	/* 17 */
};
static const int nmountcompatnames = sizeof(mountcompatnames) /
    sizeof(mountcompatnames[0]);
#endif /* COMPAT_09 || COMPAT_43 */

/* ARGSUSED */
int
sys_mount(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_mount_args /* {
		syscallarg(const char *) type;
		syscallarg(const char *) path;
		syscallarg(int) flags;
		syscallarg(void *) data;
	} */ *uap = v;
	register struct vnode *vp;
	register struct mount *mp;
	int error, flag = 0;
	char fstypename[MFSNAMELEN];
	struct vattr va;
	struct nameidata nd;
	struct vfsops *vfs;

	/*
	 * Get vnode to be covered
	 */
	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (SCARG(uap, flags) & MNT_UPDATE) {
		if ((vp->v_flag & VROOT) == 0) {
			vput(vp);
			return (EINVAL);
		}
		mp = vp->v_mount;
		flag = mp->mnt_flag;
		vfs = mp->mnt_op;
		/*
		 * We only allow the filesystem to be reloaded if it
		 * is currently mounted read-only.
		 */
		if ((SCARG(uap, flags) & MNT_RELOAD) &&
		    ((mp->mnt_flag & MNT_RDONLY) == 0)) {
			vput(vp);
			return (EOPNOTSUPP);	/* Needs translation */
		}
		mp->mnt_flag |=
		    SCARG(uap, flags) & (MNT_RELOAD | MNT_FORCE | MNT_UPDATE);
		/*
		 * Only root, or the user that did the original mount is
		 * permitted to update it.
		 */
		if (mp->mnt_stat.f_owner != p->p_ucred->cr_uid &&
		    (error = suser(p->p_ucred, &p->p_acflag)) != 0) {
			vput(vp);
			return (error);
		}
		/*
		 * Do not allow NFS export by non-root users. Silently
		 * enforce MNT_NOSUID and MNT_NODEV for non-root users.
		 */
		if (p->p_ucred->cr_uid != 0) {
			if (SCARG(uap, flags) & MNT_EXPORTED) {
				vput(vp);
				return (EPERM);
			}
			SCARG(uap, flags) |= MNT_NOSUID | MNT_NODEV;
		}
		VOP_UNLOCK(vp);
		goto update;
	}
	/*
	 * If the user is not root, ensure that they own the directory
	 * onto which we are attempting to mount.
	 */
	if ((error = VOP_GETATTR(vp, &va, p->p_ucred, p)) != 0 ||
	    (va.va_uid != p->p_ucred->cr_uid &&
		(error = suser(p->p_ucred, &p->p_acflag)) != 0)) {
		vput(vp);
		return (error);
	}
	/*
	 * Do not allow NFS export by non-root users. Silently
	 * enforce MNT_NOSUID and MNT_NODEV for non-root users.
	 */
	if (p->p_ucred->cr_uid != 0) {
		if (SCARG(uap, flags) & MNT_EXPORTED) {
			vput(vp);
			return (EPERM);
		}
		SCARG(uap, flags) |= MNT_NOSUID | MNT_NODEV;
	}
	if ((error = vinvalbuf(vp, V_SAVE, p->p_ucred, p, 0, 0)) != 0)
		return (error);
	if (vp->v_type != VDIR) {
		vput(vp);
		return (ENOTDIR);
	}
	error = copyinstr(SCARG(uap, type), fstypename, MFSNAMELEN, NULL);
	if (error) {
#if defined(COMPAT_09) || defined(COMPAT_43)
		/*
		 * Historically filesystem types were identified by number.
		 * If we get an integer for the filesystem type instead of a
		 * string, we check to see if it matches one of the historic
		 * filesystem types.
		 */
		u_long fsindex = (u_long)SCARG(uap, type);
		if (fsindex >= nmountcompatnames ||
		    mountcompatnames[fsindex] == NULL) {
			vput(vp);
			return (ENODEV);
		}
		strncpy(fstypename, mountcompatnames[fsindex], MFSNAMELEN);
#else
		vput(vp);
		return (error);
#endif
	}
#ifdef	COMPAT_10
	/* Accept `ufs' as an alias for `ffs'. */
	if (!strncmp(fstypename, "ufs", MFSNAMELEN))
		strncpy(fstypename, "ffs", MFSNAMELEN);
#endif
	if ((vfs = vfs_getopsbyname(fstypename)) == NULL) {
		vput(vp);
		return (ENODEV);
	}
	if (vp->v_mountedhere != NULL) {
		vput(vp);
		return (EBUSY);
	}

	/*
	 * Allocate and initialize the file system.
	 */
	mp = (struct mount *)malloc((u_long)sizeof(struct mount),
		M_MOUNT, M_WAITOK);
	bzero((char *)mp, (u_long)sizeof(struct mount));
	mp->mnt_op = vfs;
	if ((error = vfs_lock(mp)) != 0) {
		free((caddr_t)mp, M_MOUNT);
		vput(vp);
		return (error);
	}
	/* Do this early in case we block later. */
	vfs->vfs_refcount++;
	vp->v_mountedhere = mp;
	mp->mnt_vnodecovered = vp;
	mp->mnt_stat.f_owner = p->p_ucred->cr_uid;
update:
	/*
	 * Set the mount level flags.
	 */
	if (SCARG(uap, flags) & MNT_RDONLY)
		mp->mnt_flag |= MNT_RDONLY;
	else if (mp->mnt_flag & MNT_RDONLY)
		mp->mnt_flag |= MNT_WANTRDWR;
	mp->mnt_flag &=~ (MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
	    MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOCOREDUMP |
	    MNT_NOATIME | MNT_SYMPERM);
	mp->mnt_flag |= SCARG(uap, flags) & (MNT_NOSUID | MNT_NOEXEC |
	    MNT_NODEV | MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC |
	    MNT_NOCOREDUMP | MNT_NOATIME | MNT_SYMPERM);
	/*
	 * Mount the filesystem.
	 */
	error = VFS_MOUNT(mp, SCARG(uap, path), SCARG(uap, data), &nd, p);
	if (mp->mnt_flag & MNT_UPDATE) {
		vrele(vp);
		if (mp->mnt_flag & MNT_WANTRDWR)
			mp->mnt_flag &= ~MNT_RDONLY;
		mp->mnt_flag &=~
		    (MNT_UPDATE | MNT_RELOAD | MNT_FORCE | MNT_WANTRDWR);
		if (error)
			mp->mnt_flag = flag;
		return (error);
	}
	/*
	 * Put the new filesystem on the mount list after root.
	 */
	cache_purge(vp);
	if (!error) {
		CIRCLEQ_INSERT_TAIL(&mountlist, mp, mnt_list);
		checkdirs(vp);
		VOP_UNLOCK(vp);
		vfs_unlock(mp);
		(void) VFS_STATFS(mp, &mp->mnt_stat, p);
		error = VFS_START(mp, 0, p);
	} else {
		mp->mnt_vnodecovered->v_mountedhere = (struct mount *)0;
		vfs->vfs_refcount--;
		vfs_unlock(mp);
		free((caddr_t)mp, M_MOUNT);
		vput(vp);
	}
	return (error);
}

/*
 * Scan all active processes to see if any of them have a current
 * or root directory onto which the new filesystem has just been
 * mounted. If so, replace them with the new mount point.
 */
void
checkdirs(olddp)
	struct vnode *olddp;
{
	struct filedesc *fdp;
	struct vnode *newdp;
	struct proc *p;

	if (olddp->v_usecount == 1)
		return;
	if (VFS_ROOT(olddp->v_mountedhere, &newdp))
		panic("mount: lost mount");
	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
		fdp = p->p_fd;
		if (fdp->fd_cdir == olddp) {
			vrele(fdp->fd_cdir);
			VREF(newdp);
			fdp->fd_cdir = newdp;
		}
		if (fdp->fd_rdir == olddp) {
			vrele(fdp->fd_rdir);
			VREF(newdp);
			fdp->fd_rdir = newdp;
		}
	}
	if (rootvnode == olddp) {
		vrele(rootvnode);
		VREF(newdp);
		rootvnode = newdp;
	}
	vput(newdp);
}

/*
 * Unmount a file system.
 *
 * Note: unmount takes a path to the vnode mounted on as argument,
 * not special file (as before).
 */
/* ARGSUSED */
int
sys_unmount(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_unmount_args /* {
		syscallarg(const char *) path;
		syscallarg(int) flags;
	} */ *uap = v;
	register struct vnode *vp;
	struct mount *mp;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	mp = vp->v_mount;

	/*
	 * Only root, or the user that did the original mount is
	 * permitted to unmount this filesystem.
	 */
	if ((mp->mnt_stat.f_owner != p->p_ucred->cr_uid) &&
	    (error = suser(p->p_ucred, &p->p_acflag)) != 0) {
		vput(vp);
		return (error);
	}

	/*
	 * Don't allow unmounting the root file system.
	 */
	if (mp->mnt_flag & MNT_ROOTFS) {
		vput(vp);
		return (EINVAL);
	}

	/*
	 * Must be the root of the filesystem
	 */
	if ((vp->v_flag & VROOT) == 0) {
		vput(vp);
		return (EINVAL);
	}
	vput(vp);

	if (vfs_busy(mp))
		return (EBUSY);

	return (dounmount(mp, SCARG(uap, flags), p));
}

/*
 * Do the actual file system unmount. File system is assumed to have been
 * marked busy by the caller.
 */
int
dounmount(mp, flags, p)
	register struct mount *mp;
	int flags;
	struct proc *p;
{
	struct vnode *coveredvp;
	int error;

	coveredvp = mp->mnt_vnodecovered;
	mp->mnt_flag |= MNT_UNMOUNT;
	if ((error = vfs_lock(mp)) != 0) {
		vfs_unbusy(mp);
		return (error);
	}

	if (mp->mnt_flag & MNT_EXPUBLIC)
		vfs_setpublicfs(NULL, NULL, NULL);

	mp->mnt_flag &=~ MNT_ASYNC;
#if !defined(UVM)
	vnode_pager_umount(mp);	/* release cached vnodes */
#endif
	cache_purgevfs(mp);	/* remove cache entries for this file sys */
	if ((error = VFS_SYNC(mp, MNT_WAIT, p->p_ucred, p)) == 0 ||
	    (flags & MNT_FORCE))
		error = VFS_UNMOUNT(mp, flags, p);
	mp->mnt_flag &= ~MNT_UNMOUNT;
	vfs_unbusy(mp);
	if (error) {
		vfs_unlock(mp);
	} else {
		CIRCLEQ_REMOVE(&mountlist, mp, mnt_list);
		if (coveredvp != NULLVP) {
			vrele(coveredvp);
			coveredvp->v_mountedhere = (struct mount *)0;
		}
		mp->mnt_op->vfs_refcount--;
		vfs_unlock(mp);
		if (mp->mnt_vnodelist.lh_first != NULL)
			panic("unmount: dangling vnode");
		free((caddr_t)mp, M_MOUNT);
	}
	return (error);
}

/*
 * Sync each mounted filesystem.
 */
#ifdef DEBUG
int syncprt = 0;
struct ctldebug debug0 = { "syncprt", &syncprt };
#endif

/* ARGSUSED */
int
sys_sync(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct mount *mp, *nmp;
	int asyncflag;

	for (mp = mountlist.cqh_last; mp != (void *)&mountlist; mp = nmp) {
		/*
		 * Get the prev pointer in case we hang on vfs_busy
		 * while we are being unmounted.
		 */
		nmp = mp->mnt_list.cqe_prev;
		/*
		 * The lock check below is to avoid races with mount
		 * and unmount.
		 */
		if ((mp->mnt_flag & (MNT_MLOCK|MNT_RDONLY|MNT_MPBUSY)) == 0 &&
		    !vfs_busy(mp)) {
			asyncflag = mp->mnt_flag & MNT_ASYNC;
			mp->mnt_flag &= ~MNT_ASYNC;
#if defined(UVM)
			uvm_vnp_sync(mp);
#else
			vnode_pager_sync(mp);
#endif
			VFS_SYNC(mp, MNT_NOWAIT, p->p_ucred, p);
			if (asyncflag)
				mp->mnt_flag |= MNT_ASYNC;
			/*
			 * Get the prev pointer again, as the prior filesystem
			 * might have been unmounted while we were sync'ing.
			 */
			nmp = mp->mnt_list.cqe_prev;
			vfs_unbusy(mp);
		}
	}
#ifdef DEBUG
	if (syncprt)
		vfs_bufstats();
#endif /* DEBUG */
	return (0);
}

/*
 * Change filesystem quotas.
 */
/* ARGSUSED */
int
sys_quotactl(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_quotactl_args /* {
		syscallarg(const char *) path;
		syscallarg(int) cmd;
		syscallarg(int) uid;
		syscallarg(caddr_t) arg;
	} */ *uap = v;
	register struct mount *mp;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	mp = nd.ni_vp->v_mount;
	vrele(nd.ni_vp);
	return (VFS_QUOTACTL(mp, SCARG(uap, cmd), SCARG(uap, uid),
	    SCARG(uap, arg), p));
}

/*
 * Get filesystem statistics.
 */
/* ARGSUSED */
int
sys_statfs(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_statfs_args /* {
		syscallarg(const char *) path;
		syscallarg(struct statfs *) buf;
	} */ *uap = v;
	register struct mount *mp;
	register struct statfs *sp;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	mp = nd.ni_vp->v_mount;
	sp = &mp->mnt_stat;
	vrele(nd.ni_vp);
	if ((error = VFS_STATFS(mp, sp, p)) != 0)
		return (error);
	sp->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
	return (copyout(sp, SCARG(uap, buf), sizeof(*sp)));
}

/*
 * Get filesystem statistics.
 */
/* ARGSUSED */
int
sys_fstatfs(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_fstatfs_args /* {
		syscallarg(int) fd;
		syscallarg(struct statfs *) buf;
	} */ *uap = v;
	struct file *fp;
	struct mount *mp;
	register struct statfs *sp;
	int error;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);
	mp = ((struct vnode *)fp->f_data)->v_mount;
	sp = &mp->mnt_stat;
	if ((error = VFS_STATFS(mp, sp, p)) != 0)
		return (error);
	sp->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
	return (copyout(sp, SCARG(uap, buf), sizeof(*sp)));
}

/*
 * Get statistics on all filesystems.
 */
int
sys_getfsstat(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_getfsstat_args /* {
		syscallarg(struct statfs *) buf;
		syscallarg(long) bufsize;
		syscallarg(int) flags;
	} */ *uap = v;
	register struct mount *mp, *nmp;
	register struct statfs *sp;
	caddr_t sfsp;
	long count, maxcount, error;

	maxcount = SCARG(uap, bufsize) / sizeof(struct statfs);
	sfsp = (caddr_t)SCARG(uap, buf);
	for (count = 0,
	     mp = mountlist.cqh_first; mp != (void *)&mountlist; mp = nmp) {
		nmp = mp->mnt_list.cqe_next;
		if (sfsp && count < maxcount &&
		    ((mp->mnt_flag & MNT_MLOCK) == 0)) {
			sp = &mp->mnt_stat;
			/*
			 * If MNT_NOWAIT is specified, do not refresh the
			 * fsstat cache. MNT_WAIT overrides MNT_NOWAIT.
			 */
			if (((SCARG(uap, flags) & MNT_NOWAIT) == 0 ||
			    (SCARG(uap, flags) & MNT_WAIT)) &&
			    (error = VFS_STATFS(mp, sp, p)) != 0)
				continue;
			sp->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
			error = copyout(sp, sfsp, sizeof(*sp));
			if (error)
				return (error);
			sfsp += sizeof(*sp);
		}
		count++;
	}
	if (sfsp && count > maxcount)
		*retval = maxcount;
	else
		*retval = count;
	return (0);
}

/*
 * Change current working directory to a given file descriptor.
 */
/* ARGSUSED */
int
sys_fchdir(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_fchdir_args /* {
		syscallarg(int) fd;
	} */ *uap = v;
	register struct filedesc *fdp = p->p_fd;
	struct vnode *vp, *tdp;
	struct mount *mp;
	struct file *fp;
	int error;

	if ((error = getvnode(fdp, SCARG(uap, fd), &fp)) != 0)
		return (error);
	vp = (struct vnode *)fp->f_data;
	VREF(vp);
	VOP_LOCK(vp);
	if (vp->v_type != VDIR)
		error = ENOTDIR;
	else
		error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p);
	while (!error && (mp = vp->v_mountedhere) != NULL) {
		if (mp->mnt_flag & MNT_MLOCK) {
			mp->mnt_flag |= MNT_MWAIT;
			sleep((caddr_t)mp, PVFS);
			continue;
		}
		if ((error = VFS_ROOT(mp, &tdp)) != 0)
			break;
		vput(vp);
		vp = tdp;
	}
	VOP_UNLOCK(vp);
	if (error) {
		vrele(vp);
		return (error);
	}
	vrele(fdp->fd_cdir);
	fdp->fd_cdir = vp;
	return (0);
}

/*
 * Change current working directory (``.'').
 */
/* ARGSUSED */
int
sys_chdir(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_chdir_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	register struct filedesc *fdp = p->p_fd;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = change_dir(&nd, p)) != 0)
		return (error);
	vrele(fdp->fd_cdir);
	fdp->fd_cdir = nd.ni_vp;
	return (0);
}

/*
 * Change notion of root (``/'') directory.
 */
/* ARGSUSED */
int
sys_chroot(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_chroot_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	register struct filedesc *fdp = p->p_fd;
	int error;
	struct nameidata nd;

	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
		return (error);
	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = change_dir(&nd, p)) != 0)
		return (error);
	if (fdp->fd_rdir != NULL)
		vrele(fdp->fd_rdir);
	fdp->fd_rdir = nd.ni_vp;
	return (0);
}

/*
 * Common routine for chroot and chdir.
 */
static int
change_dir(ndp, p)
	register struct nameidata *ndp;
	struct proc *p;
{
	struct vnode *vp;
	int error;

	if ((error = namei(ndp)) != 0)
		return (error);
	vp = ndp->ni_vp;
	if (vp->v_type != VDIR)
		error = ENOTDIR;
	else
		error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p);
	VOP_UNLOCK(vp);
	if (error)
		vrele(vp);
	return (error);
}

/*
 * Check permissions, allocate an open file structure,
 * and call the device open routine if any.
 */
int
sys_open(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_open_args /* {
		syscallarg(const char *) path;
		syscallarg(int) flags;
		syscallarg(int) mode;
	} */ *uap = v;
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	register struct vnode *vp;
	int flags, cmode;
	struct file *nfp;
	int type, indx, error;
	struct flock lf;
	struct nameidata nd;
	extern struct fileops vnops;

	flags = FFLAGS(SCARG(uap, flags));
	if ((flags & (FREAD | FWRITE)) == 0)
		return (EINVAL);
	if ((error = falloc(p, &nfp, &indx)) != 0)
		return (error);
	fp = nfp;
	cmode = ((SCARG(uap, mode) &~ fdp->fd_cmask) & ALLPERMS) &~ S_ISTXT;
	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	p->p_dupfd = -indx - 1;			/* XXX check for fdopen */
	if ((error = vn_open(&nd, flags, cmode)) != 0) {
		ffree(fp);
		if ((error == ENODEV || error == ENXIO) &&
		    p->p_dupfd >= 0 &&			/* XXX from fdopen */
		    (error =
			dupfdopen(fdp, indx, p->p_dupfd, flags, error)) == 0) {
			*retval = indx;
			return (0);
		}
		if (error == ERESTART)
			error = EINTR;
		fdp->fd_ofiles[indx] = NULL;
		return (error);
	}
	p->p_dupfd = 0;
	vp = nd.ni_vp;
	fp->f_flag = flags & FMASK;
	fp->f_type = DTYPE_VNODE;
	fp->f_ops = &vnops;
	fp->f_data = (caddr_t)vp;
	if (flags & (O_EXLOCK | O_SHLOCK)) {
		lf.l_whence = SEEK_SET;
		lf.l_start = 0;
		lf.l_len = 0;
		if (flags & O_EXLOCK)
			lf.l_type = F_WRLCK;
		else
			lf.l_type = F_RDLCK;
		type = F_FLOCK;
		if ((flags & FNONBLOCK) == 0)
			type |= F_WAIT;
		VOP_UNLOCK(vp);
		error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, type);
		if (error) {
			(void) vn_close(vp, fp->f_flag, fp->f_cred, p);
			ffree(fp);
			fdp->fd_ofiles[indx] = NULL;
			return (error);
		}
		VOP_LOCK(vp);
		fp->f_flag |= FHASLOCK;
	}
	VOP_UNLOCK(vp);
	*retval = indx;
	return (0);
}

/*
 * Create a special file.
 */
/* ARGSUSED */
int
sys_mknod(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_mknod_args /* {
		syscallarg(const char *) path;
		syscallarg(int) mode;
		syscallarg(int) dev;
	} */ *uap = v;
	register struct vnode *vp;
	struct vattr vattr;
	int error;
	int whiteout = 0;
	struct nameidata nd;

	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
		return (error);
	NDINIT(&nd, CREATE, LOCKPARENT, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (vp != NULL)
		error = EEXIST;
	else {
		VATTR_NULL(&vattr);
		vattr.va_mode =
		    (SCARG(uap, mode) & ALLPERMS) &~ p->p_fd->fd_cmask;
		vattr.va_rdev = SCARG(uap, dev);
		whiteout = 0;

		switch (SCARG(uap, mode) & S_IFMT) {
		case S_IFMT:	/* used by badsect to flag bad sectors */
			vattr.va_type = VBAD;
			break;
		case S_IFCHR:
			vattr.va_type = VCHR;
			break;
		case S_IFBLK:
			vattr.va_type = VBLK;
			break;
		case S_IFWHT:
			whiteout = 1;
			break;
		default:
			error = EINVAL;
			break;
		}
	}
	if (!error) {
		VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
		if (whiteout) {
			error = VOP_WHITEOUT(nd.ni_dvp, &nd.ni_cnd, CREATE);
			if (error)
				VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
			vput(nd.ni_dvp);
		} else {
			error = VOP_MKNOD(nd.ni_dvp, &nd.ni_vp,
						&nd.ni_cnd, &vattr);
		}
	} else {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		if (vp)
			vrele(vp);
	}
	return (error);
}

/*
 * Create a named pipe.
 */
/* ARGSUSED */
int
sys_mkfifo(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
#ifndef FIFO
	return (EOPNOTSUPP);
#else
	register struct sys_mkfifo_args /* {
		syscallarg(const char *) path;
		syscallarg(int) mode;
	} */ *uap = v;
	struct vattr vattr;
	int error;
	struct nameidata nd;

	NDINIT(&nd, CREATE, LOCKPARENT, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	if (nd.ni_vp != NULL) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == nd.ni_vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vrele(nd.ni_vp);
		return (EEXIST);
	}
	VATTR_NULL(&vattr);
	vattr.va_type = VFIFO;
	vattr.va_mode = (SCARG(uap, mode) & ALLPERMS) &~ p->p_fd->fd_cmask;
	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	return (VOP_MKNOD(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr));
#endif /* FIFO */
}

/*
 * Make a hard file link.
 */
/* ARGSUSED */
int
sys_link(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_link_args /* {
		syscallarg(const char *) path;
		syscallarg(const char *) link;
	} */ *uap = v;
	register struct vnode *vp;
	struct nameidata nd;
	int error;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	NDINIT(&nd, CREATE, LOCKPARENT, UIO_USERSPACE, SCARG(uap, link), p);
	if ((error = namei(&nd)) != 0)
		goto out;
	if (nd.ni_vp) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == nd.ni_vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vrele(nd.ni_vp);
		error = EEXIST;
		goto out;
	}
	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	error = VOP_LINK(nd.ni_dvp, vp, &nd.ni_cnd);
out:
	vrele(vp);
	return (error);
}

/*
 * Make a symbolic link.
 */
/* ARGSUSED */
int
sys_symlink(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_symlink_args /* {
		syscallarg(const char *) path;
		syscallarg(const char *) link;
	} */ *uap = v;
	struct vattr vattr;
	char *path;
	int error;
	struct nameidata nd;

	MALLOC(path, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
	error = copyinstr(SCARG(uap, path), path, MAXPATHLEN, NULL);
	if (error)
		goto out;
	NDINIT(&nd, CREATE, LOCKPARENT, UIO_USERSPACE, SCARG(uap, link), p);
	if ((error = namei(&nd)) != 0)
		goto out;
	if (nd.ni_vp) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == nd.ni_vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vrele(nd.ni_vp);
		error = EEXIST;
		goto out;
	}
	VATTR_NULL(&vattr);
	vattr.va_mode = ACCESSPERMS &~ p->p_fd->fd_cmask;
	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	error = VOP_SYMLINK(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr, path);
out:
	FREE(path, M_NAMEI);
	return (error);
}

/*
 * Delete a whiteout from the filesystem.
 */
/* ARGSUSED */
int
sys_undelete(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_undelete_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, DELETE, LOCKPARENT|DOWHITEOUT, UIO_USERSPACE,
	    SCARG(uap, path), p);
	error = namei(&nd);
	if (error)
		return (error);

	if (nd.ni_vp != NULLVP || !(nd.ni_cnd.cn_flags & ISWHITEOUT)) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == nd.ni_vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		if (nd.ni_vp)
			vrele(nd.ni_vp);
		return (EEXIST);
	}

	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	if ((error = VOP_WHITEOUT(nd.ni_dvp, &nd.ni_cnd, DELETE)) != 0)
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
	vput(nd.ni_dvp);
	return (error);
}

/*
 * Delete a name from the filesystem.
 */
/* ARGSUSED */
int
sys_unlink(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_unlink_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	register struct vnode *vp;
	int error;
	struct nameidata nd;

	NDINIT(&nd, DELETE, LOCKPARENT | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;

	/*
	 * The root of a mounted filesystem cannot be deleted.
	 */
	if (vp->v_flag & VROOT) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vput(vp);
		error = EBUSY;
		goto out;
	}

#if defined(UVM)
	(void)uvm_vnp_uncache(vp);
#else
	(void)vnode_pager_uncache(vp);
#endif

	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	error = VOP_REMOVE(nd.ni_dvp, nd.ni_vp, &nd.ni_cnd);
out:
	return (error);
}

/*
 * Reposition read/write file offset.
 */
int
sys_lseek(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_lseek_args /* {
		syscallarg(int) fd;
		syscallarg(int) pad;
		syscallarg(off_t) offset;
		syscallarg(int) whence;
	} */ *uap = v;
	struct ucred *cred = p->p_ucred;
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	struct vnode *vp;
	struct vattr vattr;
	register off_t newoff;
	int error;

	if ((u_int)SCARG(uap, fd) >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[SCARG(uap, fd)]) == NULL)
		return (EBADF);

	vp = (struct vnode *)fp->f_data;
	if (fp->f_type != DTYPE_VNODE
#ifdef FIFO
	    || vp->v_type == VFIFO
#endif
	)
		return (ESPIPE);

	switch (SCARG(uap, whence)) {
	case SEEK_CUR:
		newoff = fp->f_offset + SCARG(uap, offset);
		break;
	case SEEK_END:
		error = VOP_GETATTR(vp, &vattr, cred, p);
		if (error)
			return (error);
		newoff = SCARG(uap, offset) + vattr.va_size;
		break;
	case SEEK_SET:
		newoff = SCARG(uap, offset);
		break;
	default:
		return (EINVAL);
	}
	if ((error = VOP_SEEK(vp, fp->f_offset, newoff, cred)) != 0)
		return (error);

	*(off_t *)retval = fp->f_offset = newoff;
	return (0);
}

/*
 * Check access permissions.
 */
int
sys_access(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_access_args /* {
		syscallarg(const char *) path;
		syscallarg(int) flags;
	} */ *uap = v;
	register struct ucred *cred = p->p_ucred;
	register struct vnode *vp;
	int error, flags, t_gid, t_uid;
	struct nameidata nd;

	t_uid = cred->cr_uid;
	t_gid = cred->cr_gid;
	cred->cr_uid = p->p_cred->p_ruid;
	cred->cr_gid = p->p_cred->p_rgid;
	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		goto out1;
	vp = nd.ni_vp;

	/* Flags == 0 means only check for existence. */
	if (SCARG(uap, flags)) {
		flags = 0;
		if (SCARG(uap, flags) & R_OK)
			flags |= VREAD;
		if (SCARG(uap, flags) & W_OK)
			flags |= VWRITE;
		if (SCARG(uap, flags) & X_OK)
			flags |= VEXEC;
		if ((flags & VWRITE) == 0 || (error = vn_writechk(vp)) == 0)
			error = VOP_ACCESS(vp, flags, cred, p);
	}
	vput(vp);
out1:
	cred->cr_uid = t_uid;
	cred->cr_gid = t_gid;
	return (error);
}

/*
 * Get file status; this version follows links.
 */
/* ARGSUSED */
int
sys___stat13(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys___stat13_args /* {
		syscallarg(const char *) path;
		syscallarg(struct stat *) ub;
	} */ *uap = v;
	struct stat sb;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	error = vn_stat(nd.ni_vp, &sb, p);
	vput(nd.ni_vp);
	if (error)
		return (error);
	error = copyout(&sb, SCARG(uap, ub), sizeof (sb));
	return (error);
}

/*
 * Get file status; this version does not follow links.
 */
/* ARGSUSED */
int
sys___lstat13(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys___lstat13_args /* {
		syscallarg(const char *) path;
		syscallarg(struct stat *) ub;
	} */ *uap = v;
	struct stat sb;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, NOFOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	error = vn_stat(nd.ni_vp, &sb, p);
	vput(nd.ni_vp);
	if (error)
		return (error);
	error = copyout(&sb, SCARG(uap, ub), sizeof (sb));
	return (error);
}

/*
 * Get configurable pathname variables.
 */
/* ARGSUSED */
int
sys_pathconf(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_pathconf_args /* {
		syscallarg(const char *) path;
		syscallarg(int) name;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	error = VOP_PATHCONF(nd.ni_vp, SCARG(uap, name), retval);
	vput(nd.ni_vp);
	return (error);
}

/*
 * Return target name of a symbolic link.
 */
/* ARGSUSED */
int
sys_readlink(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_readlink_args /* {
		syscallarg(const char *) path;
		syscallarg(char *) buf;
		syscallarg(int) count;
	} */ *uap = v;
	register struct vnode *vp;
	struct iovec aiov;
	struct uio auio;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, NOFOLLOW | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (vp->v_type != VLNK)
		error = EINVAL;
	else if (!(vp->v_mount->mnt_flag & MNT_SYMPERM) ||
	    (error = VOP_ACCESS(vp, VREAD, p->p_ucred, p)) == 0) {
		aiov.iov_base = SCARG(uap, buf);
		aiov.iov_len = SCARG(uap, count);
		auio.uio_iov = &aiov;
		auio.uio_iovcnt = 1;
		auio.uio_offset = 0;
		auio.uio_rw = UIO_READ;
		auio.uio_segflg = UIO_USERSPACE;
		auio.uio_procp = p;
		auio.uio_resid = SCARG(uap, count);
		error = VOP_READLINK(vp, &auio, p->p_ucred);
	}
	vput(vp);
	*retval = SCARG(uap, count) - auio.uio_resid;
	return (error);
}

/*
 * Change flags of a file given a path name.
 */
/* ARGSUSED */
int
sys_chflags(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_chflags_args /* {
		syscallarg(const char *) path;
		syscallarg(u_long) flags;
	} */ *uap = v;
	register struct vnode *vp;
	struct vattr vattr;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_mount->mnt_flag & MNT_RDONLY)
		error = EROFS;
	else {
		VATTR_NULL(&vattr);
		vattr.va_flags = SCARG(uap, flags);
		error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);
	}
	vput(vp);
	return (error);
}

/*
 * Change flags of a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchflags(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_fchflags_args /* {
		syscallarg(int) fd;
		syscallarg(u_long) flags;
	} */ *uap = v;
	struct vattr vattr;
	struct vnode *vp;
	struct file *fp;
	int error;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);
	vp = (struct vnode *)fp->f_data;
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_mount->mnt_flag & MNT_RDONLY)
		error = EROFS;
	else {
		VATTR_NULL(&vattr);
		vattr.va_flags = SCARG(uap, flags);
		error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);
	}
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Change mode of a file given path name; this version follows links.
 */
/* ARGSUSED */
int
sys_chmod(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_chmod_args /* {
		syscallarg(const char *) path;
		syscallarg(int) mode;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_mode(nd.ni_vp, SCARG(uap, mode), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Change mode of a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchmod(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_fchmod_args /* {
		syscallarg(int) fd;
		syscallarg(int) mode;
	} */ *uap = v;
	struct file *fp;
	int error;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);

	return (change_mode((struct vnode *)fp->f_data, SCARG(uap, mode), p));
}

/*
 * Change mode of a file given path name; this version does not follow links.
 */
/* ARGSUSED */
int
sys_lchmod(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_lchmod_args /* {
		syscallarg(const char *) path;
		syscallarg(int) mode;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_mode(nd.ni_vp, SCARG(uap, mode), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Common routine to set mode given a vnode.
 */
static int
change_mode(vp, mode, p)
	struct vnode *vp;
	int mode;
	struct proc *p;
{
	struct vattr vattr;
	int error;

	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_mount->mnt_flag & MNT_RDONLY)
		error = EROFS;
	else {
		VATTR_NULL(&vattr);
		vattr.va_mode = mode & ALLPERMS;
		error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);
	}
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Set ownership given a path name; this version follows links.
 */
/* ARGSUSED */
int
sys_chown(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_chown_args /* {
		syscallarg(const char *) path;
		syscallarg(uid_t) uid;
		syscallarg(gid_t) gid;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_owner(nd.ni_vp, SCARG(uap, uid), SCARG(uap, gid), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Set ownership given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchown(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_fchown_args /* {
		syscallarg(int) fd;
		syscallarg(uid_t) uid;
		syscallarg(gid_t) gid;
	} */ *uap = v;
	int error;
	struct file *fp;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);

	return (change_owner((struct vnode *)fp->f_data, SCARG(uap, uid),
	    SCARG(uap, gid), p));
}

/*
 * Set ownership given a path name; this version does not follow links.
 */
/* ARGSUSED */
int
sys_lchown(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_lchown_args /* {
		syscallarg(const char *) path;
		syscallarg(uid_t) uid;
		syscallarg(gid_t) gid;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_owner(nd.ni_vp, SCARG(uap, uid), SCARG(uap, gid), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Common routine to set ownership given a vnode.
 */
static int
change_owner(vp, uid, gid, p)
	register struct vnode *vp;
	uid_t uid;
	gid_t gid;
	struct proc *p;
{
	struct vattr vattr;
	mode_t newmode = VNOVAL;
	int error;

	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_mount->mnt_flag & MNT_RDONLY) {
		error = EROFS;
		goto out;
	}
	if ((error = VOP_GETATTR(vp, &vattr, p->p_ucred, p)) != 0)
		goto out;

	/*
	 * Unless the caller is the superuser, clear the (S_ISUID | S_ISGID)
	 * bits, but alter va_mode only if those are actually set on the vnode.
	 */
	if ((suser(p->p_ucred, NULL) != 0) &&
	    (vattr.va_mode & (S_ISUID | S_ISGID)))
		newmode = vattr.va_mode & ~(S_ISUID | S_ISGID);

	VATTR_NULL(&vattr);
	vattr.va_uid = uid;
	vattr.va_gid = gid;
	vattr.va_mode = newmode;
	error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);

out:
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Set the access and modification times given a path name; this
 * version follows links.
 */
/* ARGSUSED */
int
sys_utimes(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_utimes_args /* {
		syscallarg(const char *) path;
		syscallarg(const struct timeval *) tptr;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_utimes(nd.ni_vp, SCARG(uap, tptr), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Set the access and modification times given a file descriptor.
 */
/* ARGSUSED */
int
sys_futimes(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_futimes_args /* {
		syscallarg(int) fd;
		syscallarg(const struct timeval *) tptr;
	} */ *uap = v;
	int error;
	struct file *fp;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);

	return (change_utimes((struct vnode *)fp->f_data, SCARG(uap, tptr),
	    p));
}

/*
 * Set the access and modification times given a path name; this
 * version does not follow links.
 */
/* ARGSUSED */
int
sys_lutimes(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_lutimes_args /* {
		syscallarg(const char *) path;
		syscallarg(const struct timeval *) tptr;
	} */ *uap = v;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);

	error = change_utimes(nd.ni_vp, SCARG(uap, tptr), p);

	vrele(nd.ni_vp);
	return (error);
}

/*
 * Common routine to set access and modification times given a vnode.
 */
static int
change_utimes(vp, tptr, p)
	struct vnode *vp;
	const struct timeval *tptr;
	struct proc *p;
{
	struct timeval tv[2];
	struct vattr vattr;
	int error;

	VATTR_NULL(&vattr);
	if (tptr == NULL) {
		microtime(&tv[0]);
		tv[1] = tv[0];
		vattr.va_vaflags |= VA_UTIMES_NULL;
	} else {
		error = copyin(tptr, tv, sizeof (tv));
		if (error)
			return (error);
	}
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_mount->mnt_flag & MNT_RDONLY)
		error = EROFS;
	else {
		vattr.va_atime.tv_sec = tv[0].tv_sec;
		vattr.va_atime.tv_nsec = tv[0].tv_usec * 1000;
		vattr.va_mtime.tv_sec = tv[1].tv_sec;
		vattr.va_mtime.tv_nsec = tv[1].tv_usec * 1000;
		error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);
	}
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Truncate a file given its path name.
 */
/* ARGSUSED */
int
sys_truncate(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_truncate_args /* {
		syscallarg(const char *) path;
		syscallarg(int) pad;
		syscallarg(off_t) length;
	} */ *uap = v;
	register struct vnode *vp;
	struct vattr vattr;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_type == VDIR)
		error = EISDIR;
	else if ((error = vn_writechk(vp)) == 0 &&
	    (error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) == 0) {
		VATTR_NULL(&vattr);
		vattr.va_size = SCARG(uap, length);
		error = VOP_SETATTR(vp, &vattr, p->p_ucred, p);
	}
	vput(vp);
	return (error);
}

/*
 * Truncate a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_ftruncate(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_ftruncate_args /* {
		syscallarg(int) fd;
		syscallarg(int) pad;
		syscallarg(off_t) length;
	} */ *uap = v;
	struct vattr vattr;
	struct vnode *vp;
	struct file *fp;
	int error;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);
	if ((fp->f_flag & FWRITE) == 0)
		return (EINVAL);
	vp = (struct vnode *)fp->f_data;
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	VOP_LOCK(vp);
	if (vp->v_type == VDIR)
		error = EISDIR;
	else if ((error = vn_writechk(vp)) == 0) {
		VATTR_NULL(&vattr);
		vattr.va_size = SCARG(uap, length);
		error = VOP_SETATTR(vp, &vattr, fp->f_cred, p);
	}
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Sync an open file.
 */
/* ARGSUSED */
int
sys_fsync(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_fsync_args /* {
		syscallarg(int) fd;
	} */ *uap = v;
	register struct vnode *vp;
	struct file *fp;
	int error;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);
	vp = (struct vnode *)fp->f_data;
	VOP_LOCK(vp);
	error = VOP_FSYNC(vp, fp->f_cred, MNT_WAIT, p);
	VOP_UNLOCK(vp);
	return (error);
}

/*
 * Rename files, (standard) BSD semantics frontend.
 */
/* ARGSUSED */
int
sys_rename(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_rename_args /* {
		syscallarg(const char *) from;
		syscallarg(const char *) to;
	} */ *uap = v;

	return (rename_files(SCARG(uap, from), SCARG(uap, to), p, 0));
}

/*
 * Rename files, POSIX semantics frontend.
 */
/* ARGSUSED */
int
sys_posix_rename(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_posix_rename_args /* {
		syscallarg(const char *) from;
		syscallarg(const char *) to;
	} */ *uap = v;

	return (rename_files(SCARG(uap, from), SCARG(uap, to), p, 1));
}

/*
 * Rename files.  Source and destination must either both be directories,
 * or both not be directories.  If target is a directory, it must be empty.
 * If `from' and `to' refer to the same object, the value of the `retain'
 * argument is used to determine whether `from' will be
 *
 * (retain == 0)	deleted unless `from' and `to' refer to the same
 *			object in the file system's name space (BSD).
 * (retain == 1)	always retained (POSIX).
 */
static int
rename_files(from, to, p, retain)
	const char *from, *to;
	struct proc *p;
	int retain;
{
	register struct vnode *tvp, *fvp, *tdvp;
	struct nameidata fromnd, tond;
	int error;

	NDINIT(&fromnd, DELETE, WANTPARENT | SAVESTART, UIO_USERSPACE,
	    from, p);
	if ((error = namei(&fromnd)) != 0)
		return (error);
	fvp = fromnd.ni_vp;
	NDINIT(&tond, RENAME, LOCKPARENT | LOCKLEAF | NOCACHE | SAVESTART,
	    UIO_USERSPACE, to, p);
	if ((error = namei(&tond)) != 0) {
		VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
		vrele(fromnd.ni_dvp);
		vrele(fvp);
		goto out1;
	}
	tdvp = tond.ni_dvp;
	tvp = tond.ni_vp;

	if (tvp != NULL) {
		if (fvp->v_type == VDIR && tvp->v_type != VDIR) {
			error = ENOTDIR;
			goto out;
		} else if (fvp->v_type != VDIR && tvp->v_type == VDIR) {
			error = EISDIR;
			goto out;
		}
	}

	if (fvp == tdvp)
		error = EINVAL;

	/*
	 * Source and destination refer to the same object.
	 */
	if (fvp == tvp) {
		if (retain)
			error = -1;
		else if (fromnd.ni_dvp == tdvp &&
		    fromnd.ni_cnd.cn_namelen == tond.ni_cnd.cn_namelen &&
		    !bcmp(fromnd.ni_cnd.cn_nameptr,
		          tond.ni_cnd.cn_nameptr,
		          fromnd.ni_cnd.cn_namelen))
		error = -1;
	}

out:
	if (!error) {
		VOP_LEASE(tdvp, p, p->p_ucred, LEASE_WRITE);
		if (fromnd.ni_dvp != tdvp)
			VOP_LEASE(fromnd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
		if (tvp) {
#if defined(UVM)
			(void)uvm_vnp_uncache(tvp);
#else
			(void)vnode_pager_uncache(tvp);
#endif
			VOP_LEASE(tvp, p, p->p_ucred, LEASE_WRITE);
		}
		error = VOP_RENAME(fromnd.ni_dvp, fromnd.ni_vp, &fromnd.ni_cnd,
				   tond.ni_dvp, tond.ni_vp, &tond.ni_cnd);
	} else {
		VOP_ABORTOP(tond.ni_dvp, &tond.ni_cnd);
		if (tdvp == tvp)
			vrele(tdvp);
		else
			vput(tdvp);
		if (tvp)
			vput(tvp);
		VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
		vrele(fromnd.ni_dvp);
		vrele(fvp);
	}
	vrele(tond.ni_startdir);
	FREE(tond.ni_cnd.cn_pnbuf, M_NAMEI);
out1:
	if (fromnd.ni_startdir)
		vrele(fromnd.ni_startdir);
	FREE(fromnd.ni_cnd.cn_pnbuf, M_NAMEI);
	return (error == -1 ? 0 : error);
}

/*
 * Make a directory file.
 */
/* ARGSUSED */
int
sys_mkdir(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_mkdir_args /* {
		syscallarg(const char *) path;
		syscallarg(int) mode;
	} */ *uap = v;
	register struct vnode *vp;
	struct vattr vattr;
	int error;
	struct nameidata nd;

	NDINIT(&nd, CREATE, LOCKPARENT, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (vp != NULL) {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vrele(vp);
		return (EEXIST);
	}
	VATTR_NULL(&vattr);
	vattr.va_type = VDIR;
	vattr.va_mode = (SCARG(uap, mode) & ACCESSPERMS) &~ p->p_fd->fd_cmask;
	VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
	error = VOP_MKDIR(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
	if (!error)
		vput(nd.ni_vp);
	return (error);
}

/*
 * Remove a directory file.
 */
/* ARGSUSED */
int
sys_rmdir(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_rmdir_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	register struct vnode *vp;
	int error;
	struct nameidata nd;

	NDINIT(&nd, DELETE, LOCKPARENT | LOCKLEAF, UIO_USERSPACE,
	    SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (vp->v_type != VDIR) {
		error = ENOTDIR;
		goto out;
	}
	/*
	 * No rmdir "." please.
	 */
	if (nd.ni_dvp == vp) {
		error = EINVAL;
		goto out;
	}
	/*
	 * The root of a mounted filesystem cannot be deleted.
	 */
	if (vp->v_flag & VROOT)
		error = EBUSY;
out:
	if (!error) {
		VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
		VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
		error = VOP_RMDIR(nd.ni_dvp, nd.ni_vp, &nd.ni_cnd);
	} else {
		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
		if (nd.ni_dvp == vp)
			vrele(nd.ni_dvp);
		else
			vput(nd.ni_dvp);
		vput(vp);
	}
	return (error);
}

/*
 * Read a block of directory entries in a file system independent format.
 */
int
sys_getdents(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_getdents_args /* {
		syscallarg(int) fd;
		syscallarg(char *) buf;
		syscallarg(size_t) count;
	} */ *uap = v;
	struct file *fp;
	int error, done;

	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
		return (error);
	if ((fp->f_flag & FREAD) == 0)
		return (EBADF);
	error = vn_readdir(fp, SCARG(uap, buf), UIO_USERSPACE,
			SCARG(uap, count), &done, p, 0, 0);
	*retval = done;
	return (error);
}

/*
 * Set the mode mask for creation of filesystem nodes.
 */
int
sys_umask(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_umask_args /* {
		syscallarg(mode_t) newmask;
	} */ *uap = v;
	register struct filedesc *fdp;

	fdp = p->p_fd;
	*retval = fdp->fd_cmask;
	fdp->fd_cmask = SCARG(uap, newmask) & ALLPERMS;
	return (0);
}

/*
 * Void all references to file by ripping underlying filesystem
 * away from vnode.
 */
/* ARGSUSED */
int
sys_revoke(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	register struct sys_revoke_args /* {
		syscallarg(const char *) path;
	} */ *uap = v;
	register struct vnode *vp;
	struct vattr vattr;
	int error;
	struct nameidata nd;

	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p);
	if ((error = namei(&nd)) != 0)
		return (error);
	vp = nd.ni_vp;
	if (vp->v_type != VCHR && vp->v_type != VBLK) {
		error = EINVAL;
		goto out;
	}
	if ((error = VOP_GETATTR(vp, &vattr, p->p_ucred, p)) != 0)
		goto out;
	if (p->p_ucred->cr_uid != vattr.va_uid &&
	    (error = suser(p->p_ucred, &p->p_acflag)) != 0)
		goto out;
	if (vp->v_usecount > 1 || (vp->v_flag & VALIASED))
		vgoneall(vp);
out:
	vrele(vp);
	return (error);
}

/*
 * Convert a user file descriptor to a kernel file entry.
 */
int
getvnode(fdp, fd, fpp)
	struct filedesc *fdp;
	int fd;
	struct file **fpp;
{
	struct vnode *vp;
	struct file *fp;

	if ((u_int)fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[fd]) == NULL)
		return (EBADF);
	if (fp->f_type != DTYPE_VNODE)
		return (EINVAL);
	vp = (struct vnode *)fp->f_data;
	if (vp->v_type == VBAD)
		return (EBADF);
	*fpp = fp;
	return (0);
}