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[netbsd-mini2440.git] / sys / kern / vfs_syscalls.c

/*      $NetBSD: vfs_syscalls.c,v 1.401 2009/12/23 01:09:24 pooka Exp $ */

/*-
 * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Andrew Doran.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * 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. 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      8.42 (Berkeley) 7/31/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.401 2009/12/23 01:09:24 pooka Exp $");

#ifdef _KERNEL_OPT
#include "opt_fileassoc.h"
#include "veriexec.h"
#endif

#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/kmem.h>
#include <sys/dirent.h>
#include <sys/sysctl.h>
#include <sys/syscallargs.h>
#include <sys/vfs_syscalls.h>
#include <sys/ktrace.h>
#ifdef FILEASSOC
#include <sys/fileassoc.h>
#endif /* FILEASSOC */
#include <sys/verified_exec.h>
#include <sys/kauth.h>
#include <sys/atomic.h>
#include <sys/module.h>
#include <sys/buf.h>

#include <miscfs/genfs/genfs.h>
#include <miscfs/syncfs/syncfs.h>
#include <miscfs/specfs/specdev.h>

#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs.h>
#include <nfs/nfs_var.h>

MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount struct");

static int change_flags(struct vnode *, u_long, struct lwp *);
static int change_mode(struct vnode *, int, struct lwp *l);
static int change_owner(struct vnode *, uid_t, gid_t, struct lwp *, int);

void checkdirs(struct vnode *);

/*
 * Virtual File System System Calls
 */

/*
 * Mount a file system.
 */

/*
 * This table is used to maintain compatibility with 4.3BSD
 * and NetBSD 0.9 mount syscalls - and possibly other systems.
 * Note, the order is important!
 *
 * Do not modify this table. It should only contain filesystems
 * supported by NetBSD 0.9 and 4.3BSD.
 */
const char * const mountcompatnames[] = {
        NULL,           /* 0 = MOUNT_NONE */
        MOUNT_FFS,      /* 1 = MOUNT_UFS */
        MOUNT_NFS,      /* 2 */
        MOUNT_MFS,      /* 3 */
        MOUNT_MSDOS,    /* 4 */
        MOUNT_CD9660,   /* 5 = MOUNT_ISOFS */
        MOUNT_FDESC,    /* 6 */
        MOUNT_KERNFS,   /* 7 */
        NULL,           /* 8 = MOUNT_DEVFS */
        MOUNT_AFS,      /* 9 */
};
const int nmountcompatnames = sizeof(mountcompatnames) /
    sizeof(mountcompatnames[0]);

static int
mount_update(struct lwp *l, struct vnode *vp, const char *path, int flags,
    void *data, size_t *data_len)
{
        struct mount *mp;
        int error = 0, saved_flags;

        mp = vp->v_mount;
        saved_flags = mp->mnt_flag;

        /* We can operate only on VV_ROOT nodes. */
        if ((vp->v_vflag & VV_ROOT) == 0) {
                error = EINVAL;
                goto out;
        }

        /*
         * We only allow the filesystem to be reloaded if it
         * is currently mounted read-only.  Additionally, we
         * prevent read-write to read-only downgrades.
         */
        if ((flags & (MNT_RELOAD | MNT_RDONLY)) != 0 &&
            (mp->mnt_flag & MNT_RDONLY) == 0) {
                error = EOPNOTSUPP;     /* Needs translation */
                goto out;
        }

        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
            KAUTH_REQ_SYSTEM_MOUNT_UPDATE, mp, KAUTH_ARG(flags), data);
        if (error)
                goto out;

        if (vfs_busy(mp, NULL)) {
                error = EPERM;
                goto out;
        }

        mutex_enter(&mp->mnt_updating);

        mp->mnt_flag &= ~MNT_OP_FLAGS;
        mp->mnt_flag |= flags & (MNT_RELOAD | MNT_FORCE | MNT_UPDATE);

        /*
         * Set the mount level flags.
         */
        if (flags & MNT_RDONLY)
                mp->mnt_flag |= MNT_RDONLY;
        else if (mp->mnt_flag & MNT_RDONLY)
                mp->mnt_iflag |= IMNT_WANTRDWR;
        mp->mnt_flag &=
          ~(MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
            MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOCOREDUMP |
            MNT_NOATIME | MNT_NODEVMTIME | MNT_SYMPERM | MNT_SOFTDEP |
            MNT_LOG);
        mp->mnt_flag |= flags &
           (MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
            MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOCOREDUMP |
            MNT_NOATIME | MNT_NODEVMTIME | MNT_SYMPERM | MNT_SOFTDEP |
            MNT_LOG | MNT_IGNORE);

        error = VFS_MOUNT(mp, path, data, data_len);

        if (error && data != NULL) {
                int error2;

                /*
                 * Update failed; let's try and see if it was an
                 * export request.  For compat with 3.0 and earlier.
                 */
                error2 = vfs_hooks_reexport(mp, path, data);

                /*
                 * Only update error code if the export request was
                 * understood but some problem occurred while
                 * processing it.
                 */
                if (error2 != EJUSTRETURN)
                        error = error2;
        }

        if (mp->mnt_iflag & IMNT_WANTRDWR)
                mp->mnt_flag &= ~MNT_RDONLY;
        if (error)
                mp->mnt_flag = saved_flags;
        mp->mnt_flag &= ~MNT_OP_FLAGS;
        mp->mnt_iflag &= ~IMNT_WANTRDWR;
        if ((mp->mnt_flag & (MNT_RDONLY | MNT_ASYNC)) == 0) {
                if (mp->mnt_syncer == NULL)
                        error = vfs_allocate_syncvnode(mp);
        } else {
                if (mp->mnt_syncer != NULL)
                        vfs_deallocate_syncvnode(mp);
        }
        mutex_exit(&mp->mnt_updating);
        vfs_unbusy(mp, false, NULL);

 out:
        return (error);
}

static int
mount_get_vfsops(const char *fstype, struct vfsops **vfsops)
{
        char fstypename[sizeof(((struct statvfs *)NULL)->f_fstypename)];
        int error;

        /* Copy file-system type from userspace.  */
        error = copyinstr(fstype, fstypename, sizeof(fstypename), NULL);
        if (error) {
                /*
                 * Historically, filesystem types were identified by numbers.
                 * 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)fstype;
                if (fsindex >= nmountcompatnames ||
                    mountcompatnames[fsindex] == NULL)
                        return ENODEV;
                strlcpy(fstypename, mountcompatnames[fsindex],
                    sizeof(fstypename));
        }

        /* Accept `ufs' as an alias for `ffs', for compatibility. */
        if (strcmp(fstypename, "ufs") == 0)
                fstypename[0] = 'f';

        if ((*vfsops = vfs_getopsbyname(fstypename)) != NULL)
                return 0;

        /* If we can autoload a vfs module, try again */
        mutex_enter(&module_lock);
        (void)module_autoload(fstypename, MODULE_CLASS_VFS);
        mutex_exit(&module_lock);

        if ((*vfsops = vfs_getopsbyname(fstypename)) != NULL)
                return 0;

        return ENODEV;
}

static int
mount_domount(struct lwp *l, struct vnode **vpp, struct vfsops *vfsops,
    const char *path, int flags, void *data, size_t *data_len, u_int recurse)
{
        struct mount *mp;
        struct vnode *vp = *vpp;
        struct vattr va;
        int error;

        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
            KAUTH_REQ_SYSTEM_MOUNT_NEW, vp, KAUTH_ARG(flags), data);
        if (error)
                return error;

        /* Can't make a non-dir a mount-point (from here anyway). */
        if (vp->v_type != VDIR)
                return ENOTDIR;

        /*
         * 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, l->l_cred)) != 0 ||
            (va.va_uid != kauth_cred_geteuid(l->l_cred) &&
            (error = kauth_authorize_generic(l->l_cred,
            KAUTH_GENERIC_ISSUSER, NULL)) != 0)) {
                return error;
        }

        if (flags & MNT_EXPORTED)
                return EINVAL;

        if ((error = vinvalbuf(vp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
                return error;

        /*
         * Check if a file-system is not already mounted on this vnode.
         */
        if (vp->v_mountedhere != NULL)
                return EBUSY;

        if ((mp = vfs_mountalloc(vfsops, vp)) == NULL)
                return ENOMEM;

        mp->mnt_stat.f_owner = kauth_cred_geteuid(l->l_cred);

        /*
         * The underlying file system may refuse the mount for
         * various reasons.  Allow the user to force it to happen.
         *
         * Set the mount level flags.
         */
        mp->mnt_flag = flags &
           (MNT_FORCE | MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
            MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOCOREDUMP |
            MNT_NOATIME | MNT_NODEVMTIME | MNT_SYMPERM | MNT_SOFTDEP |
            MNT_LOG | MNT_IGNORE | MNT_RDONLY);

        mutex_enter(&mp->mnt_updating);
        error = VFS_MOUNT(mp, path, data, data_len);
        mp->mnt_flag &= ~MNT_OP_FLAGS;

        /*
         * Put the new filesystem on the mount list after root.
         */
        cache_purge(vp);
        if (error != 0) {
                vp->v_mountedhere = NULL;
                mutex_exit(&mp->mnt_updating);
                vfs_unbusy(mp, false, NULL);
                vfs_destroy(mp);
                return error;
        }

        mp->mnt_iflag &= ~IMNT_WANTRDWR;
        mutex_enter(&mountlist_lock);
        vp->v_mountedhere = mp;
        CIRCLEQ_INSERT_TAIL(&mountlist, mp, mnt_list);
        mutex_exit(&mountlist_lock);
        vn_restorerecurse(vp, recurse);
        VOP_UNLOCK(vp, 0);
        checkdirs(vp);
        if ((mp->mnt_flag & (MNT_RDONLY | MNT_ASYNC)) == 0)
                error = vfs_allocate_syncvnode(mp);
        /* Hold an additional reference to the mount across VFS_START(). */
        mutex_exit(&mp->mnt_updating);
        vfs_unbusy(mp, true, NULL);
        (void) VFS_STATVFS(mp, &mp->mnt_stat);
        error = VFS_START(mp, 0);
        if (error)
                vrele(vp);
        /* Drop reference held for VFS_START(). */
        vfs_destroy(mp);
        *vpp = NULL;
        return error;
}

static int
mount_getargs(struct lwp *l, struct vnode *vp, const char *path, int flags,
    void *data, size_t *data_len)
{
        struct mount *mp;
        int error;

        /* If MNT_GETARGS is specified, it should be the only flag. */
        if (flags & ~MNT_GETARGS)
                return EINVAL;

        mp = vp->v_mount;

        /* XXX: probably some notion of "can see" here if we want isolation. */ 
        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
            KAUTH_REQ_SYSTEM_MOUNT_GET, mp, data, NULL);
        if (error)
                return error;

        if ((vp->v_vflag & VV_ROOT) == 0)
                return EINVAL;

        if (vfs_busy(mp, NULL))
                return EPERM;

        mutex_enter(&mp->mnt_updating);
        mp->mnt_flag &= ~MNT_OP_FLAGS;
        mp->mnt_flag |= MNT_GETARGS;
        error = VFS_MOUNT(mp, path, data, data_len);
        mp->mnt_flag &= ~MNT_OP_FLAGS;
        mutex_exit(&mp->mnt_updating);

        vfs_unbusy(mp, false, NULL);
        return (error);
}

int
sys___mount50(struct lwp *l, const struct sys___mount50_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) type;
                syscallarg(const char *) path;
                syscallarg(int) flags;
                syscallarg(void *) data;
                syscallarg(size_t) data_len;
        } */

        return do_sys_mount(l, NULL, SCARG(uap, type), SCARG(uap, path),
            SCARG(uap, flags), SCARG(uap, data), UIO_USERSPACE,
            SCARG(uap, data_len), retval);
}

int
do_sys_mount(struct lwp *l, struct vfsops *vfsops, const char *type,
    const char *path, int flags, void *data, enum uio_seg data_seg,
    size_t data_len, register_t *retval)
{
        struct vnode *vp;
        void *data_buf = data;
        u_int recurse;
        int error;

        /*
         * Get vnode to be covered
         */
        error = namei_simple_user(path, NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        /*
         * A lookup in VFS_MOUNT might result in an attempt to
         * lock this vnode again, so make the lock recursive.
         */
        if (vfsops == NULL) {
                if (flags & (MNT_GETARGS | MNT_UPDATE)) {
                        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                        recurse = vn_setrecurse(vp);
                        vfsops = vp->v_mount->mnt_op;
                } else {
                        /* 'type' is userspace */
                        error = mount_get_vfsops(type, &vfsops);
                        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                        recurse = vn_setrecurse(vp);
                        if (error != 0)
                                goto done;
                }
        } else {
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                recurse = vn_setrecurse(vp);
        }

        if (data != NULL && data_seg == UIO_USERSPACE) {
                if (data_len == 0) {
                        /* No length supplied, use default for filesystem */
                        data_len = vfsops->vfs_min_mount_data;
                        if (data_len > VFS_MAX_MOUNT_DATA) {
                                error = EINVAL;
                                goto done;
                        }
                        /*
                         * Hopefully a longer buffer won't make copyin() fail.
                         * For compatibility with 3.0 and earlier.
                         */
                        if (flags & MNT_UPDATE
                            && data_len < sizeof (struct mnt_export_args30))
                                data_len = sizeof (struct mnt_export_args30);
                }
                data_buf = kmem_alloc(data_len, KM_SLEEP);

                /* NFS needs the buffer even for mnt_getargs .... */
                error = copyin(data, data_buf, data_len);
                if (error != 0)
                        goto done;
        }

        if (flags & MNT_GETARGS) {
                if (data_len == 0) {
                        error = EINVAL;
                        goto done;
                }
                error = mount_getargs(l, vp, path, flags, data_buf, &data_len);
                if (error != 0)
                        goto done;
                if (data_seg == UIO_USERSPACE)
                        error = copyout(data_buf, data, data_len);
                *retval = data_len;
        } else if (flags & MNT_UPDATE) {
                error = mount_update(l, vp, path, flags, data_buf, &data_len);
        } else {
                /* Locking is handled internally in mount_domount(). */
                error = mount_domount(l, &vp, vfsops, path, flags, data_buf,
                    &data_len, recurse);
        }

    done:
        if (vp != NULL) {
                vn_restorerecurse(vp, recurse);
                vput(vp);
        }
        if (data_buf != data)
                kmem_free(data_buf, data_len);
        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(struct vnode *olddp)
{
        struct cwdinfo *cwdi;
        struct vnode *newdp, *rele1, *rele2;
        struct proc *p;
        bool retry;

        if (olddp->v_usecount == 1)
                return;
        if (VFS_ROOT(olddp->v_mountedhere, &newdp))
                panic("mount: lost mount");

        do {
                retry = false;
                mutex_enter(proc_lock);
                PROCLIST_FOREACH(p, &allproc) {
                        if ((p->p_flag & PK_MARKER) != 0)
                                continue;
                        if ((cwdi = p->p_cwdi) == NULL)
                                continue;
                        /*
                         * Can't change to the old directory any more,
                         * so even if we see a stale value it's not a
                         * problem.
                         */
                        if (cwdi->cwdi_cdir != olddp &&
                            cwdi->cwdi_rdir != olddp)
                                continue;
                        retry = true;
                        rele1 = NULL;
                        rele2 = NULL;
                        atomic_inc_uint(&cwdi->cwdi_refcnt);
                        mutex_exit(proc_lock);
                        rw_enter(&cwdi->cwdi_lock, RW_WRITER);
                        if (cwdi->cwdi_cdir == olddp) {
                                rele1 = cwdi->cwdi_cdir;
                                vref(newdp);
                                cwdi->cwdi_cdir = newdp;
                        }
                        if (cwdi->cwdi_rdir == olddp) {
                                rele2 = cwdi->cwdi_rdir;
                                vref(newdp);
                                cwdi->cwdi_rdir = newdp;
                        }
                        rw_exit(&cwdi->cwdi_lock);
                        cwdfree(cwdi);
                        if (rele1 != NULL)
                                vrele(rele1);
                        if (rele2 != NULL)
                                vrele(rele2);
                        mutex_enter(proc_lock);
                        break;
                }
                mutex_exit(proc_lock);
        } while (retry);

        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(struct lwp *l, const struct sys_unmount_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) flags;
        } */
        struct vnode *vp;
        struct mount *mp;
        int error;
        struct nameidata nd;

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

        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
            KAUTH_REQ_SYSTEM_MOUNT_UNMOUNT, mp, NULL, NULL);
        if (error) {
                vrele(vp);
                vfs_destroy(mp);
                return (error);
        }

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

        /*
         * Must be the root of the filesystem
         */
        if ((vp->v_vflag & VV_ROOT) == 0) {
                vrele(vp);
                vfs_destroy(mp);
                return (EINVAL);
        }

        vrele(vp);
        error = dounmount(mp, SCARG(uap, flags), l);
        vfs_destroy(mp);
        return error;
}

/*
 * Do the actual file system unmount.  File system is assumed to have
 * been locked by the caller.
 *
 * => Caller hold reference to the mount, explicitly for dounmount().
 */
int
dounmount(struct mount *mp, int flags, struct lwp *l)
{
        struct vnode *coveredvp;
        int error;
        int async;
        int used_syncer;

#if NVERIEXEC > 0
        error = veriexec_unmountchk(mp);
        if (error)
                return (error);
#endif /* NVERIEXEC > 0 */

        /*
         * XXX Freeze syncer.  Must do this before locking the
         * mount point.  See dounmount() for details.
         */
        mutex_enter(&syncer_mutex);
        rw_enter(&mp->mnt_unmounting, RW_WRITER);
        if ((mp->mnt_iflag & IMNT_GONE) != 0) {
                rw_exit(&mp->mnt_unmounting);
                mutex_exit(&syncer_mutex);
                return ENOENT;
        }

        used_syncer = (mp->mnt_syncer != NULL);

        /*
         * XXX Syncer must be frozen when we get here.  This should really
         * be done on a per-mountpoint basis, but the syncer doesn't work
         * like that.
         *
         * The caller of dounmount() must acquire syncer_mutex because
         * the syncer itself acquires locks in syncer_mutex -> vfs_busy
         * order, and we must preserve that order to avoid deadlock.
         *
         * So, if the file system did not use the syncer, now is
         * the time to release the syncer_mutex.
         */
        if (used_syncer == 0)
                mutex_exit(&syncer_mutex);

        mp->mnt_iflag |= IMNT_UNMOUNT;
        async = mp->mnt_flag & MNT_ASYNC;
        mp->mnt_flag &= ~MNT_ASYNC;
        cache_purgevfs(mp);     /* remove cache entries for this file sys */
        if (mp->mnt_syncer != NULL)
                vfs_deallocate_syncvnode(mp);
        error = 0;
        if ((mp->mnt_flag & MNT_RDONLY) == 0) {
                error = VFS_SYNC(mp, MNT_WAIT, l->l_cred);
        }
        vfs_scrubvnlist(mp);
        if (error == 0 || (flags & MNT_FORCE))
                error = VFS_UNMOUNT(mp, flags);
        if (error) {
                if ((mp->mnt_flag & (MNT_RDONLY | MNT_ASYNC)) == 0)
                        (void) vfs_allocate_syncvnode(mp);
                mp->mnt_iflag &= ~IMNT_UNMOUNT;
                mp->mnt_flag |= async;
                rw_exit(&mp->mnt_unmounting);
                if (used_syncer)
                        mutex_exit(&syncer_mutex);
                return (error);
        }
        vfs_scrubvnlist(mp);
        mutex_enter(&mountlist_lock);
        if ((coveredvp = mp->mnt_vnodecovered) != NULLVP)
                coveredvp->v_mountedhere = NULL;
        CIRCLEQ_REMOVE(&mountlist, mp, mnt_list);
        mp->mnt_iflag |= IMNT_GONE;
        mutex_exit(&mountlist_lock);
        if (TAILQ_FIRST(&mp->mnt_vnodelist) != NULL)
                panic("unmount: dangling vnode");
        if (used_syncer)
                mutex_exit(&syncer_mutex);
        vfs_hooks_unmount(mp);
        rw_exit(&mp->mnt_unmounting);
        vfs_destroy(mp);        /* reference from mount() */
        if (coveredvp != NULLVP)
                vrele(coveredvp);
        return (0);
}

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

/* ARGSUSED */
int
sys_sync(struct lwp *l, const void *v, register_t *retval)
{
        struct mount *mp, *nmp;
        int asyncflag;

        if (l == NULL)
                l = &lwp0;

        mutex_enter(&mountlist_lock);
        for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
             mp = nmp) {
                if (vfs_busy(mp, &nmp)) {
                        continue;
                }
                mutex_enter(&mp->mnt_updating);
                if ((mp->mnt_flag & MNT_RDONLY) == 0) {
                        asyncflag = mp->mnt_flag & MNT_ASYNC;
                        mp->mnt_flag &= ~MNT_ASYNC;
                        VFS_SYNC(mp, MNT_NOWAIT, l->l_cred);
                        if (asyncflag)
                                 mp->mnt_flag |= MNT_ASYNC;
                }
                mutex_exit(&mp->mnt_updating);
                vfs_unbusy(mp, false, &nmp);
        }
        mutex_exit(&mountlist_lock);
#ifdef DEBUG
        if (syncprt)
                vfs_bufstats();
#endif /* DEBUG */
        return (0);
}

/*
 * Change filesystem quotas.
 */
/* ARGSUSED */
int
sys_quotactl(struct lwp *l, const struct sys_quotactl_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) cmd;
                syscallarg(int) uid;
                syscallarg(void *) arg;
        } */
        struct mount *mp;
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        mp = vp->v_mount;
        error = VFS_QUOTACTL(mp, SCARG(uap, cmd), SCARG(uap, uid),
            SCARG(uap, arg));
        vrele(vp);
        return (error);
}

int
dostatvfs(struct mount *mp, struct statvfs *sp, struct lwp *l, int flags,
    int root)
{
        struct cwdinfo *cwdi = l->l_proc->p_cwdi;
        int error = 0;

        /*
         * If MNT_NOWAIT or MNT_LAZY is specified, do not
         * refresh the fsstat cache. MNT_WAIT or MNT_LAZY
         * overrides MNT_NOWAIT.
         */
        if (flags == MNT_NOWAIT || flags == MNT_LAZY ||
            (flags != MNT_WAIT && flags != 0)) {
                memcpy(sp, &mp->mnt_stat, sizeof(*sp));
                goto done;
        }

        /* Get the filesystem stats now */
        memset(sp, 0, sizeof(*sp));
        if ((error = VFS_STATVFS(mp, sp)) != 0) {
                return error;
        }

        if (cwdi->cwdi_rdir == NULL)
                (void)memcpy(&mp->mnt_stat, sp, sizeof(mp->mnt_stat));
done:
        if (cwdi->cwdi_rdir != NULL) {
                size_t len;
                char *bp;
                char c;
                char *path = PNBUF_GET();

                bp = path + MAXPATHLEN;
                *--bp = '\0';
                rw_enter(&cwdi->cwdi_lock, RW_READER);
                error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp, path,
                    MAXPATHLEN / 2, 0, l);
                rw_exit(&cwdi->cwdi_lock);
                if (error) {
                        PNBUF_PUT(path);
                        return error;
                }
                len = strlen(bp);
                if (len != 1) {
                        /*
                         * for mount points that are below our root, we can see
                         * them, so we fix up the pathname and return them. The
                         * rest we cannot see, so we don't allow viewing the
                         * data.
                         */
                        if (strncmp(bp, sp->f_mntonname, len) == 0 &&
                            ((c = sp->f_mntonname[len]) == '/' || c == '\0')) {
                                (void)strlcpy(sp->f_mntonname,
                                    c == '\0' ? "/" : &sp->f_mntonname[len],
                                    sizeof(sp->f_mntonname));
                        } else {
                                if (root)
                                        (void)strlcpy(sp->f_mntonname, "/",
                                            sizeof(sp->f_mntonname));
                                else
                                        error = EPERM;
                        }
                }
                PNBUF_PUT(path);
        }
        sp->f_flag = mp->mnt_flag & MNT_VISFLAGMASK;
        return error;
}

/*
 * Get filesystem statistics by path.
 */
int
do_sys_pstatvfs(struct lwp *l, const char *path, int flags, struct statvfs *sb)
{
        struct mount *mp;
        int error;
        struct vnode *vp;

        error = namei_simple_user(path, NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return error;
        mp = vp->v_mount;
        error = dostatvfs(mp, sb, l, flags, 1);
        vrele(vp);
        return error;
}

/* ARGSUSED */
int
sys_statvfs1(struct lwp *l, const struct sys_statvfs1_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(struct statvfs *) buf;
                syscallarg(int) flags;
        } */
        struct statvfs *sb;
        int error;

        sb = STATVFSBUF_GET();
        error = do_sys_pstatvfs(l, SCARG(uap, path), SCARG(uap, flags), sb);
        if (error == 0)
                error = copyout(sb, SCARG(uap, buf), sizeof(*sb));
        STATVFSBUF_PUT(sb);
        return error;
}

/*
 * Get filesystem statistics by fd.
 */
int
do_sys_fstatvfs(struct lwp *l, int fd, int flags, struct statvfs *sb)
{
        file_t *fp;
        struct mount *mp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(fd, &fp)) != 0)
                return (error);
        mp = ((struct vnode *)fp->f_data)->v_mount;
        error = dostatvfs(mp, sb, curlwp, flags, 1);
        fd_putfile(fd);
        return error;
}

/* ARGSUSED */
int
sys_fstatvfs1(struct lwp *l, const struct sys_fstatvfs1_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(struct statvfs *) buf;
                syscallarg(int) flags;
        } */
        struct statvfs *sb;
        int error;

        sb = STATVFSBUF_GET();
        error = do_sys_fstatvfs(l, SCARG(uap, fd), SCARG(uap, flags), sb);
        if (error == 0)
                error = copyout(sb, SCARG(uap, buf), sizeof(*sb));
        STATVFSBUF_PUT(sb);
        return error;
}


/*
 * Get statistics on all filesystems.
 */
int
do_sys_getvfsstat(struct lwp *l, void *sfsp, size_t bufsize, int flags,
    int (*copyfn)(const void *, void *, size_t), size_t entry_sz,
    register_t *retval)
{
        int root = 0;
        struct proc *p = l->l_proc;
        struct mount *mp, *nmp;
        struct statvfs *sb;
        size_t count, maxcount;
        int error = 0;

        sb = STATVFSBUF_GET();
        maxcount = bufsize / entry_sz;
        mutex_enter(&mountlist_lock);
        count = 0;
        for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
             mp = nmp) {
                if (vfs_busy(mp, &nmp)) {
                        continue;
                }
                if (sfsp && count < maxcount) {
                        error = dostatvfs(mp, sb, l, flags, 0);
                        if (error) {
                                vfs_unbusy(mp, false, &nmp);
                                error = 0;
                                continue;
                        }
                        error = copyfn(sb, sfsp, entry_sz);
                        if (error) {
                                vfs_unbusy(mp, false, NULL);
                                goto out;
                        }
                        sfsp = (char *)sfsp + entry_sz;
                        root |= strcmp(sb->f_mntonname, "/") == 0;
                }
                count++;
                vfs_unbusy(mp, false, &nmp);
        }
        mutex_exit(&mountlist_lock);

        if (root == 0 && p->p_cwdi->cwdi_rdir) {
                /*
                 * fake a root entry
                 */
                error = dostatvfs(p->p_cwdi->cwdi_rdir->v_mount,
                    sb, l, flags, 1);
                if (error != 0)
                        goto out;
                if (sfsp) {
                        error = copyfn(sb, sfsp, entry_sz);
                        if (error != 0)
                                goto out;
                }
                count++;
        }
        if (sfsp && count > maxcount)
                *retval = maxcount;
        else
                *retval = count;
out:
        STATVFSBUF_PUT(sb);
        return error;
}

int
sys_getvfsstat(struct lwp *l, const struct sys_getvfsstat_args *uap, register_t *retval)
{
        /* {
                syscallarg(struct statvfs *) buf;
                syscallarg(size_t) bufsize;
                syscallarg(int) flags;
        } */

        return do_sys_getvfsstat(l, SCARG(uap, buf), SCARG(uap, bufsize),
            SCARG(uap, flags), copyout, sizeof (struct statvfs), retval);
}

/*
 * Change current working directory to a given file descriptor.
 */
/* ARGSUSED */
int
sys_fchdir(struct lwp *l, const struct sys_fchdir_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
        } */
        struct proc *p = l->l_proc;
        struct cwdinfo *cwdi;
        struct vnode *vp, *tdp;
        struct mount *mp;
        file_t *fp;
        int error, fd;

        /* fd_getvnode() will use the descriptor for us */
        fd = SCARG(uap, fd);
        if ((error = fd_getvnode(fd, &fp)) != 0)
                return (error);
        vp = fp->f_data;

        vref(vp);
        vn_lock(vp,  LK_EXCLUSIVE | LK_RETRY);
        if (vp->v_type != VDIR)
                error = ENOTDIR;
        else
                error = VOP_ACCESS(vp, VEXEC, l->l_cred);
        if (error) {
                vput(vp);
                goto out;
        }
        while ((mp = vp->v_mountedhere) != NULL) {
                error = vfs_busy(mp, NULL);
                vput(vp);
                if (error != 0)
                        goto out;
                error = VFS_ROOT(mp, &tdp);
                vfs_unbusy(mp, false, NULL);
                if (error)
                        goto out;
                vp = tdp;
        }
        VOP_UNLOCK(vp, 0);

        /*
         * Disallow changing to a directory not under the process's
         * current root directory (if there is one).
         */
        cwdi = p->p_cwdi;
        rw_enter(&cwdi->cwdi_lock, RW_WRITER);
        if (cwdi->cwdi_rdir && !vn_isunder(vp, NULL, l)) {
                vrele(vp);
                error = EPERM;  /* operation not permitted */
        } else {
                vrele(cwdi->cwdi_cdir);
                cwdi->cwdi_cdir = vp;
        }
        rw_exit(&cwdi->cwdi_lock);

 out:
        fd_putfile(fd);
        return (error);
}

/*
 * Change this process's notion of the root directory to a given file
 * descriptor.
 */
int
sys_fchroot(struct lwp *l, const struct sys_fchroot_args *uap, register_t *retval)
{
        struct proc *p = l->l_proc;
        struct vnode    *vp;
        file_t  *fp;
        int              error, fd = SCARG(uap, fd);

        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_CHROOT,
            KAUTH_REQ_SYSTEM_CHROOT_FCHROOT, NULL, NULL, NULL)) != 0)
                return error;
        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(fd, &fp)) != 0)
                return error;
        vp = fp->f_data;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (vp->v_type != VDIR)
                error = ENOTDIR;
        else
                error = VOP_ACCESS(vp, VEXEC, l->l_cred);
        VOP_UNLOCK(vp, 0);
        if (error)
                goto out;
        vref(vp);

        change_root(p->p_cwdi, vp, l);

 out:
        fd_putfile(fd);
        return (error);
}

/*
 * Change current working directory (``.'').
 */
/* ARGSUSED */
int
sys_chdir(struct lwp *l, const struct sys_chdir_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */
        struct proc *p = l->l_proc;
        struct cwdinfo *cwdi;
        int error;
        struct vnode *vp;

        if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
                                  &vp, l)) != 0)
                return (error);
        cwdi = p->p_cwdi;
        rw_enter(&cwdi->cwdi_lock, RW_WRITER);
        vrele(cwdi->cwdi_cdir);
        cwdi->cwdi_cdir = vp;
        rw_exit(&cwdi->cwdi_lock);
        return (0);
}

/*
 * Change notion of root (``/'') directory.
 */
/* ARGSUSED */
int
sys_chroot(struct lwp *l, const struct sys_chroot_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */
        struct proc *p = l->l_proc;
        int error;
        struct vnode *vp;

        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_CHROOT,
            KAUTH_REQ_SYSTEM_CHROOT_CHROOT, NULL, NULL, NULL)) != 0)
                return (error);
        if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
                                  &vp, l)) != 0)
                return (error);

        change_root(p->p_cwdi, vp, l);

        return (0);
}

/*
 * Common routine for chroot and fchroot.
 * NB: callers need to properly authorize the change root operation.
 */
void
change_root(struct cwdinfo *cwdi, struct vnode *vp, struct lwp *l)
{

        rw_enter(&cwdi->cwdi_lock, RW_WRITER);
        if (cwdi->cwdi_rdir != NULL)
                vrele(cwdi->cwdi_rdir);
        cwdi->cwdi_rdir = vp;

        /*
         * Prevent escaping from chroot by putting the root under
         * the working directory.  Silently chdir to / if we aren't
         * already there.
         */
        if (!vn_isunder(cwdi->cwdi_cdir, vp, l)) {
                /*
                 * XXX would be more failsafe to change directory to a
                 * deadfs node here instead
                 */
                vrele(cwdi->cwdi_cdir);
                vref(vp);
                cwdi->cwdi_cdir = vp;
        }
        rw_exit(&cwdi->cwdi_lock);
}

/*
 * Common routine for chroot and chdir.
 */
int
chdir_lookup(const char *path, int where, struct vnode **vpp, struct lwp *l)
{
        struct nameidata nd;
        int error;

        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, where,
            path);
        if ((error = namei(&nd)) != 0)
                return (error);
        *vpp = nd.ni_vp;
        if ((*vpp)->v_type != VDIR)
                error = ENOTDIR;
        else
                error = VOP_ACCESS(*vpp, VEXEC, l->l_cred);

        if (error)
                vput(*vpp);
        else
                VOP_UNLOCK(*vpp, 0);
        return (error);
}

/*
 * Check permissions, allocate an open file structure,
 * and call the device open routine if any.
 */
int
sys_open(struct lwp *l, const struct sys_open_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) flags;
                syscallarg(int) mode;
        } */
        struct proc *p = l->l_proc;
        struct cwdinfo *cwdi = p->p_cwdi;
        file_t *fp;
        struct vnode *vp;
        int flags, cmode;
        int type, indx, error;
        struct flock lf;
        struct nameidata nd;

        flags = FFLAGS(SCARG(uap, flags));
        if ((flags & (FREAD | FWRITE)) == 0)
                return (EINVAL);
        if ((error = fd_allocfile(&fp, &indx)) != 0)
                return (error);
        /* We're going to read cwdi->cwdi_cmask unlocked here. */
        cmode = ((SCARG(uap, mode) &~ cwdi->cwdi_cmask) & ALLPERMS) &~ S_ISTXT;
        NDINIT(&nd, LOOKUP, FOLLOW | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        l->l_dupfd = -indx - 1;                 /* XXX check for fdopen */
        if ((error = vn_open(&nd, flags, cmode)) != 0) {
                fd_abort(p, fp, indx);
                if ((error == EDUPFD || error == EMOVEFD) &&
                    l->l_dupfd >= 0 &&                  /* XXX from fdopen */
                    (error =
                        fd_dupopen(l->l_dupfd, &indx, flags, error)) == 0) {
                        *retval = indx;
                        return (0);
                }
                if (error == ERESTART)
                        error = EINTR;
                return (error);
        }

        l->l_dupfd = 0;
        vp = nd.ni_vp;
        fp->f_flag = flags & FMASK;
        fp->f_type = DTYPE_VNODE;
        fp->f_ops = &vnops;
        fp->f_data = 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, 0);
                error = VOP_ADVLOCK(vp, fp, F_SETLK, &lf, type);
                if (error) {
                        (void) vn_close(vp, fp->f_flag, fp->f_cred);
                        fd_abort(p, fp, indx);
                        return (error);
                }
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                atomic_or_uint(&fp->f_flag, FHASLOCK);
        }
        VOP_UNLOCK(vp, 0);
        *retval = indx;
        fd_affix(p, fp, indx);
        return (0);
}

static void
vfs__fhfree(fhandle_t *fhp)
{
        size_t fhsize;

        if (fhp == NULL) {
                return;
        }
        fhsize = FHANDLE_SIZE(fhp);
        kmem_free(fhp, fhsize);
}

/*
 * vfs_composefh: compose a filehandle.
 */

int
vfs_composefh(struct vnode *vp, fhandle_t *fhp, size_t *fh_size)
{
        struct mount *mp;
        struct fid *fidp;
        int error;
        size_t needfhsize;
        size_t fidsize;

        mp = vp->v_mount;
        fidp = NULL;
        if (*fh_size < FHANDLE_SIZE_MIN) {
                fidsize = 0;
        } else {
                fidsize = *fh_size - offsetof(fhandle_t, fh_fid);
                if (fhp != NULL) {
                        memset(fhp, 0, *fh_size);
                        fhp->fh_fsid = mp->mnt_stat.f_fsidx;
                        fidp = &fhp->fh_fid;
                }
        }
        error = VFS_VPTOFH(vp, fidp, &fidsize);
        needfhsize = FHANDLE_SIZE_FROM_FILEID_SIZE(fidsize);
        if (error == 0 && *fh_size < needfhsize) {
                error = E2BIG;
        }
        *fh_size = needfhsize;
        return error;
}

int
vfs_composefh_alloc(struct vnode *vp, fhandle_t **fhpp)
{
        struct mount *mp;
        fhandle_t *fhp;
        size_t fhsize;
        size_t fidsize;
        int error;

        *fhpp = NULL;
        mp = vp->v_mount;
        fidsize = 0;
        error = VFS_VPTOFH(vp, NULL, &fidsize);
        KASSERT(error != 0);
        if (error != E2BIG) {
                goto out;
        }
        fhsize = FHANDLE_SIZE_FROM_FILEID_SIZE(fidsize);
        fhp = kmem_zalloc(fhsize, KM_SLEEP);
        if (fhp == NULL) {
                error = ENOMEM;
                goto out;
        }
        fhp->fh_fsid = mp->mnt_stat.f_fsidx;
        error = VFS_VPTOFH(vp, &fhp->fh_fid, &fidsize);
        if (error == 0) {
                KASSERT((FHANDLE_SIZE(fhp) == fhsize &&
                    FHANDLE_FILEID(fhp)->fid_len == fidsize));
                *fhpp = fhp;
        } else {
                kmem_free(fhp, fhsize);
        }
out:
        return error;
}

void
vfs_composefh_free(fhandle_t *fhp)
{

        vfs__fhfree(fhp);
}

/*
 * vfs_fhtovp: lookup a vnode by a filehandle.
 */

int
vfs_fhtovp(fhandle_t *fhp, struct vnode **vpp)
{
        struct mount *mp;
        int error;

        *vpp = NULL;
        mp = vfs_getvfs(FHANDLE_FSID(fhp));
        if (mp == NULL) {
                error = ESTALE;
                goto out;
        }
        if (mp->mnt_op->vfs_fhtovp == NULL) {
                error = EOPNOTSUPP;
                goto out;
        }
        error = VFS_FHTOVP(mp, FHANDLE_FILEID(fhp), vpp);
out:
        return error;
}

/*
 * vfs_copyinfh_alloc: allocate and copyin a filehandle, given
 * the needed size.
 */

int
vfs_copyinfh_alloc(const void *ufhp, size_t fhsize, fhandle_t **fhpp)
{
        fhandle_t *fhp;
        int error;

        *fhpp = NULL;
        if (fhsize > FHANDLE_SIZE_MAX) {
                return EINVAL;
        }
        if (fhsize < FHANDLE_SIZE_MIN) {
                return EINVAL;
        }
again:
        fhp = kmem_alloc(fhsize, KM_SLEEP);
        if (fhp == NULL) {
                return ENOMEM;
        }
        error = copyin(ufhp, fhp, fhsize);
        if (error == 0) {
                /* XXX this check shouldn't be here */
                if (FHANDLE_SIZE(fhp) == fhsize) {
                        *fhpp = fhp;
                        return 0;
                } else if (fhsize == NFSX_V2FH && FHANDLE_SIZE(fhp) < fhsize) {
                        /*
                         * a kludge for nfsv2 padded handles.
                         */
                        size_t sz;

                        sz = FHANDLE_SIZE(fhp);
                        kmem_free(fhp, fhsize);
                        fhsize = sz;
                        goto again;
                } else {
                        /*
                         * userland told us wrong size.
                         */
                        error = EINVAL;
                }
        }
        kmem_free(fhp, fhsize);
        return error;
}

void
vfs_copyinfh_free(fhandle_t *fhp)
{

        vfs__fhfree(fhp);
}

/*
 * Get file handle system call
 */
int
sys___getfh30(struct lwp *l, const struct sys___getfh30_args *uap, register_t *retval)
{
        /* {
                syscallarg(char *) fname;
                syscallarg(fhandle_t *) fhp;
                syscallarg(size_t *) fh_size;
        } */
        struct vnode *vp;
        fhandle_t *fh;
        int error;
        struct nameidata nd;
        size_t sz;
        size_t usz;

        /*
         * Must be super user
         */
        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_FILEHANDLE,
            0, NULL, NULL, NULL);
        if (error)
                return (error);
        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, fname));
        error = namei(&nd);
        if (error)
                return (error);
        vp = nd.ni_vp;
        error = vfs_composefh_alloc(vp, &fh);
        vput(vp);
        if (error != 0) {
                goto out;
        }
        error = copyin(SCARG(uap, fh_size), &usz, sizeof(size_t));
        if (error != 0) {
                goto out;
        }
        sz = FHANDLE_SIZE(fh);
        error = copyout(&sz, SCARG(uap, fh_size), sizeof(size_t));
        if (error != 0) {
                goto out;
        }
        if (usz >= sz) {
                error = copyout(fh, SCARG(uap, fhp), sz);
        } else {
                error = E2BIG;
        }
out:
        vfs_composefh_free(fh);
        return (error);
}

/*
 * Open a file given a file handle.
 *
 * Check permissions, allocate an open file structure,
 * and call the device open routine if any.
 */

int
dofhopen(struct lwp *l, const void *ufhp, size_t fhsize, int oflags,
    register_t *retval)
{
        file_t *fp;
        struct vnode *vp = NULL;
        kauth_cred_t cred = l->l_cred;
        file_t *nfp;
        int type, indx, error=0;
        struct flock lf;
        struct vattr va;
        fhandle_t *fh;
        int flags;
        proc_t *p;

        p = curproc;

        /*
         * Must be super user
         */
        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_FILEHANDLE,
            0, NULL, NULL, NULL)))
                return (error);

        flags = FFLAGS(oflags);
        if ((flags & (FREAD | FWRITE)) == 0)
                return (EINVAL);
        if ((flags & O_CREAT))
                return (EINVAL);
        if ((error = fd_allocfile(&nfp, &indx)) != 0)
                return (error);
        fp = nfp;
        error = vfs_copyinfh_alloc(ufhp, fhsize, &fh);
        if (error != 0) {
                goto bad;
        }
        error = vfs_fhtovp(fh, &vp);
        if (error != 0) {
                goto bad;
        }

        /* Now do an effective vn_open */

        if (vp->v_type == VSOCK) {
                error = EOPNOTSUPP;
                goto bad;
        }
        error = vn_openchk(vp, cred, flags);
        if (error != 0)
                goto bad;
        if (flags & O_TRUNC) {
                VOP_UNLOCK(vp, 0);                      /* XXX */
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);   /* XXX */
                vattr_null(&va);
                va.va_size = 0;
                error = VOP_SETATTR(vp, &va, cred);
                if (error)
                        goto bad;
        }
        if ((error = VOP_OPEN(vp, flags, cred)) != 0)
                goto bad;
        if (flags & FWRITE) {
                mutex_enter(&vp->v_interlock);
                vp->v_writecount++;
                mutex_exit(&vp->v_interlock);
        }

        /* done with modified vn_open, now finish what sys_open does. */

        fp->f_flag = flags & FMASK;
        fp->f_type = DTYPE_VNODE;
        fp->f_ops = &vnops;
        fp->f_data = 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, 0);
                error = VOP_ADVLOCK(vp, fp, F_SETLK, &lf, type);
                if (error) {
                        (void) vn_close(vp, fp->f_flag, fp->f_cred);
                        fd_abort(p, fp, indx);
                        return (error);
                }
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                atomic_or_uint(&fp->f_flag, FHASLOCK);
        }
        VOP_UNLOCK(vp, 0);
        *retval = indx;
        fd_affix(p, fp, indx);
        vfs_copyinfh_free(fh);
        return (0);

bad:
        fd_abort(p, fp, indx);
        if (vp != NULL)
                vput(vp);
        vfs_copyinfh_free(fh);
        return (error);
}

int
sys___fhopen40(struct lwp *l, const struct sys___fhopen40_args *uap, register_t *retval)
{
        /* {
                syscallarg(const void *) fhp;
                syscallarg(size_t) fh_size;
                syscallarg(int) flags;
        } */

        return dofhopen(l, SCARG(uap, fhp), SCARG(uap, fh_size),
            SCARG(uap, flags), retval);
}

int
do_fhstat(struct lwp *l, const void *ufhp, size_t fhsize, struct stat *sb)
{
        int error;
        fhandle_t *fh;
        struct vnode *vp;

        /*
         * Must be super user
         */
        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_FILEHANDLE,
            0, NULL, NULL, NULL)))
                return (error);

        error = vfs_copyinfh_alloc(ufhp, fhsize, &fh);
        if (error != 0)
                return error;

        error = vfs_fhtovp(fh, &vp);
        vfs_copyinfh_free(fh);
        if (error != 0)
                return error;

        error = vn_stat(vp, sb);
        vput(vp);
        return error;
}


/* ARGSUSED */
int
sys___fhstat50(struct lwp *l, const struct sys___fhstat50_args *uap, register_t *retval)
{
        /* {
                syscallarg(const void *) fhp;
                syscallarg(size_t) fh_size;
                syscallarg(struct stat *) sb;
        } */
        struct stat sb;
        int error;

        error = do_fhstat(l, SCARG(uap, fhp), SCARG(uap, fh_size), &sb);
        if (error)
                return error;
        return copyout(&sb, SCARG(uap, sb), sizeof(sb));
}

int
do_fhstatvfs(struct lwp *l, const void *ufhp, size_t fhsize, struct statvfs *sb,
    int flags)
{
        fhandle_t *fh;
        struct mount *mp;
        struct vnode *vp;
        int error;

        /*
         * Must be super user
         */
        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_FILEHANDLE,
            0, NULL, NULL, NULL)))
                return error;

        error = vfs_copyinfh_alloc(ufhp, fhsize, &fh);
        if (error != 0)
                return error;

        error = vfs_fhtovp(fh, &vp);
        vfs_copyinfh_free(fh);
        if (error != 0)
                return error;

        mp = vp->v_mount;
        error = dostatvfs(mp, sb, l, flags, 1);
        vput(vp);
        return error;
}

/* ARGSUSED */
int
sys___fhstatvfs140(struct lwp *l, const struct sys___fhstatvfs140_args *uap, register_t *retval)
{
        /* {
                syscallarg(const void *) fhp;
                syscallarg(size_t) fh_size;
                syscallarg(struct statvfs *) buf;
                syscallarg(int) flags;
        } */
        struct statvfs *sb = STATVFSBUF_GET();
        int error;

        error = do_fhstatvfs(l, SCARG(uap, fhp), SCARG(uap, fh_size), sb,
            SCARG(uap, flags));
        if (error == 0)
                error = copyout(sb, SCARG(uap, buf), sizeof(*sb));
        STATVFSBUF_PUT(sb);
        return error;
}

/*
 * Create a special file.
 */
/* ARGSUSED */
int
sys___mknod50(struct lwp *l, const struct sys___mknod50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(mode_t) mode;
                syscallarg(dev_t) dev;
        } */
        return do_sys_mknod(l, SCARG(uap, path), SCARG(uap, mode),
            SCARG(uap, dev), retval, UIO_USERSPACE);
}

int
do_sys_mknod(struct lwp *l, const char *pathname, mode_t mode, dev_t dev,
    register_t *retval, enum uio_seg seg)
{
        struct proc *p = l->l_proc;
        struct vnode *vp;
        struct vattr vattr;
        int error, optype;
        struct nameidata nd;
        char *path;
        const char *cpath;

        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MKNOD,
            0, NULL, NULL, NULL)) != 0)
                return (error);

        optype = VOP_MKNOD_DESCOFFSET;

        VERIEXEC_PATH_GET(pathname, seg, cpath, path);
        NDINIT(&nd, CREATE, LOCKPARENT | TRYEMULROOT, seg, cpath);

        if ((error = namei(&nd)) != 0)
                goto out;
        vp = nd.ni_vp;
        if (vp != NULL)
                error = EEXIST;
        else {
                vattr_null(&vattr);
                /* We will read cwdi->cwdi_cmask unlocked. */
                vattr.va_mode = (mode & ALLPERMS) &~ p->p_cwdi->cwdi_cmask;
                vattr.va_rdev = dev;

                switch (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:
                        optype = VOP_WHITEOUT_DESCOFFSET;
                        break;
                case S_IFREG:
#if NVERIEXEC > 0
                        error = veriexec_openchk(l, nd.ni_vp, nd.ni_dirp,
                            O_CREAT);
#endif /* NVERIEXEC > 0 */
                        vattr.va_type = VREG;
                        vattr.va_rdev = VNOVAL;
                        optype = VOP_CREATE_DESCOFFSET;
                        break;
                default:
                        error = EINVAL;
                        break;
                }
        }
        if (!error) {
                switch (optype) {
                case VOP_WHITEOUT_DESCOFFSET:
                        error = VOP_WHITEOUT(nd.ni_dvp, &nd.ni_cnd, CREATE);
                        if (error)
                                VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
                        vput(nd.ni_dvp);
                        break;

                case VOP_MKNOD_DESCOFFSET:
                        error = VOP_MKNOD(nd.ni_dvp, &nd.ni_vp,
                                                &nd.ni_cnd, &vattr);
                        if (error == 0)
                                vput(nd.ni_vp);
                        break;

                case VOP_CREATE_DESCOFFSET:
                        error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp,
                                                &nd.ni_cnd, &vattr);
                        if (error == 0)
                                vput(nd.ni_vp);
                        break;
                }
        } 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);
        }
out:
        VERIEXEC_PATH_PUT(path);
        return (error);
}

/*
 * Create a named pipe.
 */
/* ARGSUSED */
int
sys_mkfifo(struct lwp *l, const struct sys_mkfifo_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) mode;
        } */
        struct proc *p = l->l_proc;
        struct vattr vattr;
        int error;
        struct nameidata nd;

        NDINIT(&nd, CREATE, LOCKPARENT | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        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;
        /* We will read cwdi->cwdi_cmask unlocked. */
        vattr.va_mode = (SCARG(uap, mode) & ALLPERMS) &~ p->p_cwdi->cwdi_cmask;
        error = VOP_MKNOD(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
        if (error == 0)
                vput(nd.ni_vp);
        return (error);
}

/*
 * Make a hard file link.
 */
/* ARGSUSED */
int
sys_link(struct lwp *l, const struct sys_link_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(const char *) link;
        } */
        struct vnode *vp;
        struct nameidata nd;
        int error;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        NDINIT(&nd, CREATE, LOCKPARENT | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, link));
        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;
        }
        error = VOP_LINK(nd.ni_dvp, vp, &nd.ni_cnd);
out:
        vrele(vp);
        return (error);
}

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

        path = PNBUF_GET();
        error = copyinstr(SCARG(uap, path), path, MAXPATHLEN, NULL);
        if (error)
                goto out;
        NDINIT(&nd, CREATE, LOCKPARENT | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, link));
        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_type = VLNK;
        /* We will read cwdi->cwdi_cmask unlocked. */
        vattr.va_mode = ACCESSPERMS &~ p->p_cwdi->cwdi_cmask;
        error = VOP_SYMLINK(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr, path);
        if (error == 0)
                vput(nd.ni_vp);
out:
        PNBUF_PUT(path);
        return (error);
}

/*
 * Delete a whiteout from the filesystem.
 */
/* ARGSUSED */
int
sys_undelete(struct lwp *l, const struct sys_undelete_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */
        int error;
        struct nameidata nd;

        NDINIT(&nd, DELETE, LOCKPARENT | DOWHITEOUT | TRYEMULROOT,
            UIO_USERSPACE, SCARG(uap, path));
        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);
        }
        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(struct lwp *l, const struct sys_unlink_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */

        return do_sys_unlink(SCARG(uap, path), UIO_USERSPACE);
}

int
do_sys_unlink(const char *arg, enum uio_seg seg)
{
        struct vnode *vp;
        int error;
        struct nameidata nd;
        char *path;
        const char *cpath;

        VERIEXEC_PATH_GET(arg, seg, cpath, path);
        NDINIT(&nd, DELETE, LOCKPARENT | LOCKLEAF | TRYEMULROOT, seg, cpath);

        if ((error = namei(&nd)) != 0)
                goto out;
        vp = nd.ni_vp;

        /*
         * The root of a mounted filesystem cannot be deleted.
         */
        if (vp->v_vflag & VV_ROOT) {
                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 NVERIEXEC > 0
        /* Handle remove requests for veriexec entries. */
        if ((error = veriexec_removechk(curlwp, nd.ni_vp, nd.ni_dirp)) != 0) {
                VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
                if (nd.ni_dvp == vp)
                        vrele(nd.ni_dvp);
                else
                        vput(nd.ni_dvp);
                vput(vp);
                goto out;
        }
#endif /* NVERIEXEC > 0 */
        
#ifdef FILEASSOC
        (void)fileassoc_file_delete(vp);
#endif /* FILEASSOC */
        error = VOP_REMOVE(nd.ni_dvp, nd.ni_vp, &nd.ni_cnd);
out:
        VERIEXEC_PATH_PUT(path);
        return (error);
}

/*
 * Reposition read/write file offset.
 */
int
sys_lseek(struct lwp *l, const struct sys_lseek_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(int) pad;
                syscallarg(off_t) offset;
                syscallarg(int) whence;
        } */
        kauth_cred_t cred = l->l_cred;
        file_t *fp;
        struct vnode *vp;
        struct vattr vattr;
        off_t newoff;
        int error, fd;

        fd = SCARG(uap, fd);

        if ((fp = fd_getfile(fd)) == NULL)
                return (EBADF);

        vp = fp->f_data;
        if (fp->f_type != DTYPE_VNODE || vp->v_type == VFIFO) {
                error = ESPIPE;
                goto out;
        }

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

/*
 * Positional read system call.
 */
int
sys_pread(struct lwp *l, const struct sys_pread_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(void *) buf;
                syscallarg(size_t) nbyte;
                syscallarg(off_t) offset;
        } */
        file_t *fp;
        struct vnode *vp;
        off_t offset;
        int error, fd = SCARG(uap, fd);

        if ((fp = fd_getfile(fd)) == NULL)
                return (EBADF);

        if ((fp->f_flag & FREAD) == 0) {
                fd_putfile(fd);
                return (EBADF);
        }

        vp = fp->f_data;
        if (fp->f_type != DTYPE_VNODE || vp->v_type == VFIFO) {
                error = ESPIPE;
                goto out;
        }

        offset = SCARG(uap, offset);

        /*
         * XXX This works because no file systems actually
         * XXX take any action on the seek operation.
         */
        if ((error = VOP_SEEK(vp, fp->f_offset, offset, fp->f_cred)) != 0)
                goto out;

        /* dofileread() will unuse the descriptor for us */
        return (dofileread(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
            &offset, 0, retval));

 out:
        fd_putfile(fd);
        return (error);
}

/*
 * Positional scatter read system call.
 */
int
sys_preadv(struct lwp *l, const struct sys_preadv_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(const struct iovec *) iovp;
                syscallarg(int) iovcnt;
                syscallarg(off_t) offset;
        } */
        off_t offset = SCARG(uap, offset);

        return do_filereadv(SCARG(uap, fd), SCARG(uap, iovp),
            SCARG(uap, iovcnt), &offset, 0, retval);
}

/*
 * Positional write system call.
 */
int
sys_pwrite(struct lwp *l, const struct sys_pwrite_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(const void *) buf;
                syscallarg(size_t) nbyte;
                syscallarg(off_t) offset;
        } */
        file_t *fp;
        struct vnode *vp;
        off_t offset;
        int error, fd = SCARG(uap, fd);

        if ((fp = fd_getfile(fd)) == NULL)
                return (EBADF);

        if ((fp->f_flag & FWRITE) == 0) {
                fd_putfile(fd);
                return (EBADF);
        }

        vp = fp->f_data;
        if (fp->f_type != DTYPE_VNODE || vp->v_type == VFIFO) {
                error = ESPIPE;
                goto out;
        }

        offset = SCARG(uap, offset);

        /*
         * XXX This works because no file systems actually
         * XXX take any action on the seek operation.
         */
        if ((error = VOP_SEEK(vp, fp->f_offset, offset, fp->f_cred)) != 0)
                goto out;

        /* dofilewrite() will unuse the descriptor for us */
        return (dofilewrite(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
            &offset, 0, retval));

 out:
        fd_putfile(fd);
        return (error);
}

/*
 * Positional gather write system call.
 */
int
sys_pwritev(struct lwp *l, const struct sys_pwritev_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(const struct iovec *) iovp;
                syscallarg(int) iovcnt;
                syscallarg(off_t) offset;
        } */
        off_t offset = SCARG(uap, offset);

        return do_filewritev(SCARG(uap, fd), SCARG(uap, iovp),
            SCARG(uap, iovcnt), &offset, 0, retval);
}

/*
 * Check access permissions.
 */
int
sys_access(struct lwp *l, const struct sys_access_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) flags;
        } */
        kauth_cred_t cred;
        struct vnode *vp;
        int error, flags;
        struct nameidata nd;

        cred = kauth_cred_dup(l->l_cred);
        kauth_cred_seteuid(cred, kauth_cred_getuid(l->l_cred));
        kauth_cred_setegid(cred, kauth_cred_getgid(l->l_cred));
        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        /* Override default credentials */
        nd.ni_cnd.cn_cred = cred;
        if ((error = namei(&nd)) != 0)
                goto out;
        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;

                error = VOP_ACCESS(vp, flags, cred);
                if (!error && (flags & VWRITE))
                        error = vn_writechk(vp);
        }
        vput(vp);
out:
        kauth_cred_free(cred);
        return (error);
}

/*
 * Common code for all sys_stat functions, including compat versions.
 */
int
do_sys_stat(const char *path, unsigned int nd_flags, struct stat *sb)
{
        int error;
        struct nameidata nd;

        NDINIT(&nd, LOOKUP, nd_flags | LOCKLEAF | TRYEMULROOT,
            UIO_USERSPACE, path);
        error = namei(&nd);
        if (error != 0)
                return error;
        error = vn_stat(nd.ni_vp, sb);
        vput(nd.ni_vp);
        return error;
}

/*
 * Get file status; this version follows links.
 */
/* ARGSUSED */
int
sys___stat50(struct lwp *l, const struct sys___stat50_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(struct stat *) ub;
        } */
        struct stat sb;
        int error;

        error = do_sys_stat(SCARG(uap, path), FOLLOW, &sb);
        if (error)
                return error;
        return copyout(&sb, SCARG(uap, ub), sizeof(sb));
}

/*
 * Get file status; this version does not follow links.
 */
/* ARGSUSED */
int
sys___lstat50(struct lwp *l, const struct sys___lstat50_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(struct stat *) ub;
        } */
        struct stat sb;
        int error;

        error = do_sys_stat(SCARG(uap, path), NOFOLLOW, &sb);
        if (error)
                return error;
        return copyout(&sb, SCARG(uap, ub), sizeof(sb));
}

/*
 * Get configurable pathname variables.
 */
/* ARGSUSED */
int
sys_pathconf(struct lwp *l, const struct sys_pathconf_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) name;
        } */
        int error;
        struct nameidata nd;

        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        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(struct lwp *l, const struct sys_readlink_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(char *) buf;
                syscallarg(size_t) count;
        } */
        struct vnode *vp;
        struct iovec aiov;
        struct uio auio;
        int error;
        struct nameidata nd;

        NDINIT(&nd, LOOKUP, NOFOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        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, l->l_cred)) == 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;
                KASSERT(l == curlwp);
                auio.uio_vmspace = l->l_proc->p_vmspace;
                auio.uio_resid = SCARG(uap, count);
                error = VOP_READLINK(vp, &auio, l->l_cred);
        }
        vput(vp);
        *retval = SCARG(uap, count) - auio.uio_resid;
        return (error);
}

/*
 * Change flags of a file given a path name.
 */
/* ARGSUSED */
int
sys_chflags(struct lwp *l, const struct sys_chflags_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(u_long) flags;
        } */
        struct vnode *vp;
        int error;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        error = change_flags(vp, SCARG(uap, flags), l);
        vput(vp);
        return (error);
}

/*
 * Change flags of a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchflags(struct lwp *l, const struct sys_fchflags_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(u_long) flags;
        } */
        struct vnode *vp;
        file_t *fp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        vp = fp->f_data;
        error = change_flags(vp, SCARG(uap, flags), l);
        VOP_UNLOCK(vp, 0);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Change flags of a file given a path name; this version does
 * not follow links.
 */
int
sys_lchflags(struct lwp *l, const struct sys_lchflags_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(u_long) flags;
        } */
        struct vnode *vp;
        int error;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_NOFOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        error = change_flags(vp, SCARG(uap, flags), l);
        vput(vp);
        return (error);
}

/*
 * Common routine to change flags of a file.
 */
int
change_flags(struct vnode *vp, u_long flags, struct lwp *l)
{
        struct vattr vattr;
        int error;

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        /*
         * Non-superusers cannot change the flags on devices, even if they
         * own them.
         */
        if (kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER, NULL)) {
                if ((error = VOP_GETATTR(vp, &vattr, l->l_cred)) != 0)
                        goto out;
                if (vattr.va_type == VCHR || vattr.va_type == VBLK) {
                        error = EINVAL;
                        goto out;
                }
        }
        vattr_null(&vattr);
        vattr.va_flags = flags;
        error = VOP_SETATTR(vp, &vattr, l->l_cred);
out:
        return (error);
}

/*
 * Change mode of a file given path name; this version follows links.
 */
/* ARGSUSED */
int
sys_chmod(struct lwp *l, const struct sys_chmod_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) mode;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_mode(vp, SCARG(uap, mode), l);

        vrele(vp);
        return (error);
}

/*
 * Change mode of a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchmod(struct lwp *l, const struct sys_fchmod_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(int) mode;
        } */
        file_t *fp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        error = change_mode(fp->f_data, SCARG(uap, mode), l);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Change mode of a file given path name; this version does not follow links.
 */
/* ARGSUSED */
int
sys_lchmod(struct lwp *l, const struct sys_lchmod_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) mode;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_NOFOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_mode(vp, SCARG(uap, mode), l);

        vrele(vp);
        return (error);
}

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

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        vattr_null(&vattr);
        vattr.va_mode = mode & ALLPERMS;
        error = VOP_SETATTR(vp, &vattr, l->l_cred);
        VOP_UNLOCK(vp, 0);
        return (error);
}

/*
 * Set ownership given a path name; this version follows links.
 */
/* ARGSUSED */
int
sys_chown(struct lwp *l, const struct sys_chown_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_owner(vp, SCARG(uap, uid), SCARG(uap, gid), l, 0);

        vrele(vp);
        return (error);
}

/*
 * Set ownership given a path name; this version follows links.
 * Provides POSIX semantics.
 */
/* ARGSUSED */
int
sys___posix_chown(struct lwp *l, const struct sys___posix_chown_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_owner(vp, SCARG(uap, uid), SCARG(uap, gid), l, 1);

        vrele(vp);
        return (error);
}

/*
 * Set ownership given a file descriptor.
 */
/* ARGSUSED */
int
sys_fchown(struct lwp *l, const struct sys_fchown_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        file_t *fp;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        error = change_owner(fp->f_data, SCARG(uap, uid), SCARG(uap, gid),
            l, 0);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Set ownership given a file descriptor, providing POSIX/XPG semantics.
 */
/* ARGSUSED */
int
sys___posix_fchown(struct lwp *l, const struct sys___posix_fchown_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        file_t *fp;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        error = change_owner(fp->f_data, SCARG(uap, uid), SCARG(uap, gid),
            l, 1);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Set ownership given a path name; this version does not follow links.
 */
/* ARGSUSED */
int
sys_lchown(struct lwp *l, const struct sys_lchown_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_NOFOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_owner(vp, SCARG(uap, uid), SCARG(uap, gid), l, 0);

        vrele(vp);
        return (error);
}

/*
 * Set ownership given a path name; this version does not follow links.
 * Provides POSIX/XPG semantics.
 */
/* ARGSUSED */
int
sys___posix_lchown(struct lwp *l, const struct sys___posix_lchown_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(uid_t) uid;
                syscallarg(gid_t) gid;
        } */
        int error;
        struct vnode *vp;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_NOFOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);

        error = change_owner(vp, SCARG(uap, uid), SCARG(uap, gid), l, 1);

        vrele(vp);
        return (error);
}

/*
 * Common routine to set ownership given a vnode.
 */
static int
change_owner(struct vnode *vp, uid_t uid, gid_t gid, struct lwp *l,
    int posix_semantics)
{
        struct vattr vattr;
        mode_t newmode;
        int error;

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if ((error = VOP_GETATTR(vp, &vattr, l->l_cred)) != 0)
                goto out;

#define CHANGED(x) ((int)(x) != -1)
        newmode = vattr.va_mode;
        if (posix_semantics) {
                /*
                 * POSIX/XPG semantics: if the caller is not the super-user,
                 * clear set-user-id and set-group-id bits.  Both POSIX and
                 * the XPG consider the behaviour for calls by the super-user
                 * implementation-defined; we leave the set-user-id and set-
                 * group-id settings intact in that case.
                 */
                if (kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER,
                                      NULL) != 0)
                        newmode &= ~(S_ISUID | S_ISGID);
        } else {
                /*
                 * NetBSD semantics: when changing owner and/or group,
                 * clear the respective bit(s).
                 */
                if (CHANGED(uid))
                        newmode &= ~S_ISUID;
                if (CHANGED(gid))
                        newmode &= ~S_ISGID;
        }
        /* Update va_mode iff altered. */
        if (vattr.va_mode == newmode)
                newmode = VNOVAL;

        vattr_null(&vattr);
        vattr.va_uid = CHANGED(uid) ? uid : (uid_t)VNOVAL;
        vattr.va_gid = CHANGED(gid) ? gid : (gid_t)VNOVAL;
        vattr.va_mode = newmode;
        error = VOP_SETATTR(vp, &vattr, l->l_cred);
#undef CHANGED

out:
        VOP_UNLOCK(vp, 0);
        return (error);
}

/*
 * Set the access and modification times given a path name; this
 * version follows links.
 */
/* ARGSUSED */
int
sys___utimes50(struct lwp *l, const struct sys___utimes50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(const struct timeval *) tptr;
        } */

        return do_sys_utimes(l, NULL, SCARG(uap, path), FOLLOW,
            SCARG(uap, tptr), UIO_USERSPACE);
}

/*
 * Set the access and modification times given a file descriptor.
 */
/* ARGSUSED */
int
sys___futimes50(struct lwp *l, const struct sys___futimes50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(const struct timeval *) tptr;
        } */
        int error;
        file_t *fp;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        error = do_sys_utimes(l, fp->f_data, NULL, 0, SCARG(uap, tptr),
            UIO_USERSPACE);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Set the access and modification times given a path name; this
 * version does not follow links.
 */
int
sys___lutimes50(struct lwp *l, const struct sys___lutimes50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(const struct timeval *) tptr;
        } */

        return do_sys_utimes(l, NULL, SCARG(uap, path), NOFOLLOW,
            SCARG(uap, tptr), UIO_USERSPACE);
}

/*
 * Common routine to set access and modification times given a vnode.
 */
int
do_sys_utimes(struct lwp *l, struct vnode *vp, const char *path, int flag,
    const struct timeval *tptr, enum uio_seg seg)
{
        struct vattr vattr;
        int error, dorele = 0;
        namei_simple_flags_t sflags;

        bool vanull, setbirthtime;
        struct timespec ts[2];

        /* 
         * I have checked all callers and they pass either FOLLOW,
         * NOFOLLOW, or 0 (when they don't pass a path), and NOFOLLOW
         * is 0. More to the point, they don't pass anything else.
         * Let's keep it that way at least until the namei interfaces
         * are fully sanitized.
         */
        KASSERT(flag == NOFOLLOW || flag == FOLLOW);
        sflags = (flag == FOLLOW) ? 
                NSM_FOLLOW_TRYEMULROOT : NSM_NOFOLLOW_TRYEMULROOT;

        if (tptr == NULL) {
                vanull = true;
                nanotime(&ts[0]);
                ts[1] = ts[0];
        } else {
                struct timeval tv[2];

                vanull = false;
                if (seg != UIO_SYSSPACE) {
                        error = copyin(tptr, tv, sizeof (tv));
                        if (error != 0)
                                return error;
                        tptr = tv;
                }
                TIMEVAL_TO_TIMESPEC(&tptr[0], &ts[0]);
                TIMEVAL_TO_TIMESPEC(&tptr[1], &ts[1]);
        }

        if (vp == NULL) {
                /* note: SEG describes TPTR, not PATH; PATH is always user */
                error = namei_simple_user(path, sflags, &vp);
                if (error != 0)
                        return error;
                dorele = 1;
        }

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        setbirthtime = (VOP_GETATTR(vp, &vattr, l->l_cred) == 0 &&
            timespeccmp(&ts[1], &vattr.va_birthtime, <));
        vattr_null(&vattr);
        vattr.va_atime = ts[0];
        vattr.va_mtime = ts[1];
        if (setbirthtime)
                vattr.va_birthtime = ts[1];
        if (vanull)
                vattr.va_vaflags |= VA_UTIMES_NULL;
        error = VOP_SETATTR(vp, &vattr, l->l_cred);
        VOP_UNLOCK(vp, 0);

        if (dorele != 0)
                vrele(vp);

        return error;
}

/*
 * Truncate a file given its path name.
 */
/* ARGSUSED */
int
sys_truncate(struct lwp *l, const struct sys_truncate_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) pad;
                syscallarg(off_t) length;
        } */
        struct vnode *vp;
        struct vattr vattr;
        int error;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (vp->v_type == VDIR)
                error = EISDIR;
        else if ((error = vn_writechk(vp)) == 0 &&
            (error = VOP_ACCESS(vp, VWRITE, l->l_cred)) == 0) {
                vattr_null(&vattr);
                vattr.va_size = SCARG(uap, length);
                error = VOP_SETATTR(vp, &vattr, l->l_cred);
        }
        vput(vp);
        return (error);
}

/*
 * Truncate a file given a file descriptor.
 */
/* ARGSUSED */
int
sys_ftruncate(struct lwp *l, const struct sys_ftruncate_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(int) pad;
                syscallarg(off_t) length;
        } */
        struct vattr vattr;
        struct vnode *vp;
        file_t *fp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        if ((fp->f_flag & FWRITE) == 0) {
                error = EINVAL;
                goto out;
        }
        vp = fp->f_data;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        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);
        }
        VOP_UNLOCK(vp, 0);
 out:
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Sync an open file.
 */
/* ARGSUSED */
int
sys_fsync(struct lwp *l, const struct sys_fsync_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
        } */
        struct vnode *vp;
        file_t *fp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        vp = fp->f_data;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_FSYNC(vp, fp->f_cred, FSYNC_WAIT, 0, 0);
        VOP_UNLOCK(vp, 0);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Sync a range of file data.  API modeled after that found in AIX.
 *
 * FDATASYNC indicates that we need only save enough metadata to be able
 * to re-read the written data.  Note we duplicate AIX's requirement that
 * the file be open for writing.
 */
/* ARGSUSED */
int
sys_fsync_range(struct lwp *l, const struct sys_fsync_range_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(int) flags;
                syscallarg(off_t) start;
                syscallarg(off_t) length;
        } */
        struct vnode *vp;
        file_t *fp;
        int flags, nflags;
        off_t s, e, len;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);

        if ((fp->f_flag & FWRITE) == 0) {
                error = EBADF;
                goto out;
        }

        flags = SCARG(uap, flags);
        if (((flags & (FDATASYNC | FFILESYNC)) == 0) ||
            ((~flags & (FDATASYNC | FFILESYNC)) == 0)) {
                error = EINVAL;
                goto out;
        }
        /* Now set up the flags for value(s) to pass to VOP_FSYNC() */
        if (flags & FDATASYNC)
                nflags = FSYNC_DATAONLY | FSYNC_WAIT;
        else
                nflags = FSYNC_WAIT;
        if (flags & FDISKSYNC)
                nflags |= FSYNC_CACHE;

        len = SCARG(uap, length);
        /* If length == 0, we do the whole file, and s = l = 0 will do that */
        if (len) {
                s = SCARG(uap, start);
                e = s + len;
                if (e < s) {
                        error = EINVAL;
                        goto out;
                }
        } else {
                e = 0;
                s = 0;
        }

        vp = fp->f_data;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_FSYNC(vp, fp->f_cred, nflags, s, e);
        VOP_UNLOCK(vp, 0);
out:
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Sync the data of an open file.
 */
/* ARGSUSED */
int
sys_fdatasync(struct lwp *l, const struct sys_fdatasync_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
        } */
        struct vnode *vp;
        file_t *fp;
        int error;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        if ((fp->f_flag & FWRITE) == 0) {
                fd_putfile(SCARG(uap, fd));
                return (EBADF);
        }
        vp = fp->f_data;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_FSYNC(vp, fp->f_cred, FSYNC_WAIT|FSYNC_DATAONLY, 0, 0);
        VOP_UNLOCK(vp, 0);
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Rename files, (standard) BSD semantics frontend.
 */
/* ARGSUSED */
int
sys_rename(struct lwp *l, const struct sys_rename_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) from;
                syscallarg(const char *) to;
        } */

        return (do_sys_rename(SCARG(uap, from), SCARG(uap, to), UIO_USERSPACE, 0));
}

/*
 * Rename files, POSIX semantics frontend.
 */
/* ARGSUSED */
int
sys___posix_rename(struct lwp *l, const struct sys___posix_rename_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) from;
                syscallarg(const char *) to;
        } */

        return (do_sys_rename(SCARG(uap, from), SCARG(uap, to), UIO_USERSPACE, 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).
 */
int
do_sys_rename(const char *from, const char *to, enum uio_seg seg, int retain)
{
        struct vnode *tvp, *fvp, *tdvp;
        struct nameidata fromnd, tond;
        struct mount *fs;
        struct lwp *l = curlwp;
        struct proc *p;
        uint32_t saveflag;
        int error;

        NDINIT(&fromnd, DELETE, LOCKPARENT | SAVESTART | TRYEMULROOT | INRENAME,
            seg, from);
        if ((error = namei(&fromnd)) != 0)
                return (error);
        if (fromnd.ni_dvp != fromnd.ni_vp)
                VOP_UNLOCK(fromnd.ni_dvp, 0);
        fvp = fromnd.ni_vp;

        fs = fvp->v_mount;
        error = VFS_RENAMELOCK_ENTER(fs);
        if (error) {
                VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
                vrele(fromnd.ni_dvp);
                vrele(fvp);
                goto out1;
        }

        /*
         * close, partially, yet another race - ideally we should only
         * go as far as getting fromnd.ni_dvp before getting the per-fs
         * lock, and then continue to get fromnd.ni_vp, but we can't do
         * that with namei as it stands.
         *
         * This still won't prevent rmdir from nuking fromnd.ni_vp
         * under us. The real fix is to get the locks in the right
         * order and do the lookups in the right places, but that's a
         * major rototill.
         *
         * Preserve the SAVESTART in cn_flags, because who knows what
         * might happen if we don't.
         *
         * Note: this logic (as well as this whole function) is cloned
         * in nfs_serv.c. Proceed accordingly.
         */
        vrele(fvp);
        if ((fromnd.ni_cnd.cn_namelen == 1 && 
             fromnd.ni_cnd.cn_nameptr[0] == '.') ||
            (fromnd.ni_cnd.cn_namelen == 2 && 
             fromnd.ni_cnd.cn_nameptr[0] == '.' &&
             fromnd.ni_cnd.cn_nameptr[1] == '.')) {
                error = EINVAL;
                VFS_RENAMELOCK_EXIT(fs);
                VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
                vrele(fromnd.ni_dvp);
                goto out1;
        }
        saveflag = fromnd.ni_cnd.cn_flags & SAVESTART;
        fromnd.ni_cnd.cn_flags &= ~SAVESTART;
        vn_lock(fromnd.ni_dvp, LK_EXCLUSIVE | LK_RETRY);
        error = relookup(fromnd.ni_dvp, &fromnd.ni_vp, &fromnd.ni_cnd);
        fromnd.ni_cnd.cn_flags |= saveflag;
        if (error) {
                VOP_UNLOCK(fromnd.ni_dvp, 0);
                VFS_RENAMELOCK_EXIT(fs);
                VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
                vrele(fromnd.ni_dvp);
                goto out1;
        }
        VOP_UNLOCK(fromnd.ni_vp, 0);
        if (fromnd.ni_dvp != fromnd.ni_vp)
                VOP_UNLOCK(fromnd.ni_dvp, 0);
        fvp = fromnd.ni_vp;

        NDINIT(&tond, RENAME,
            LOCKPARENT | LOCKLEAF | NOCACHE | SAVESTART | TRYEMULROOT
              | INRENAME | (fvp->v_type == VDIR ? CREATEDIR : 0),
            seg, to);
        if ((error = namei(&tond)) != 0) {
                VFS_RENAMELOCK_EXIT(fs);
                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 &&
                    !memcmp(fromnd.ni_cnd.cn_nameptr,
                          tond.ni_cnd.cn_nameptr,
                          fromnd.ni_cnd.cn_namelen))
                error = -1;
        }

#if NVERIEXEC > 0
        if (!error) {
                char *f1, *f2;
                size_t f1_len;
                size_t f2_len;

                f1_len = fromnd.ni_cnd.cn_namelen + 1;
                f1 = kmem_alloc(f1_len, KM_SLEEP);
                strlcpy(f1, fromnd.ni_cnd.cn_nameptr, f1_len);

                f2_len = tond.ni_cnd.cn_namelen + 1;
                f2 = kmem_alloc(f2_len, KM_SLEEP);
                strlcpy(f2, tond.ni_cnd.cn_nameptr, f2_len);

                error = veriexec_renamechk(l, fvp, f1, tvp, f2);

                kmem_free(f1, f1_len);
                kmem_free(f2, f2_len);
        }
#endif /* NVERIEXEC > 0 */

out:
        p = l->l_proc;
        if (!error) {
                error = VOP_RENAME(fromnd.ni_dvp, fromnd.ni_vp, &fromnd.ni_cnd,
                                   tond.ni_dvp, tond.ni_vp, &tond.ni_cnd);
                VFS_RENAMELOCK_EXIT(fs);
        } else {
                VOP_ABORTOP(tond.ni_dvp, &tond.ni_cnd);
                if (tdvp == tvp)
                        vrele(tdvp);
                else
                        vput(tdvp);
                if (tvp)
                        vput(tvp);
                VFS_RENAMELOCK_EXIT(fs);
                VOP_ABORTOP(fromnd.ni_dvp, &fromnd.ni_cnd);
                vrele(fromnd.ni_dvp);
                vrele(fvp);
        }
        vrele(tond.ni_startdir);
        PNBUF_PUT(tond.ni_cnd.cn_pnbuf);
out1:
        if (fromnd.ni_startdir)
                vrele(fromnd.ni_startdir);
        PNBUF_PUT(fromnd.ni_cnd.cn_pnbuf);
        return (error == -1 ? 0 : error);
}

/*
 * Make a directory file.
 */
/* ARGSUSED */
int
sys_mkdir(struct lwp *l, const struct sys_mkdir_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
                syscallarg(int) mode;
        } */

        return do_sys_mkdir(SCARG(uap, path), SCARG(uap, mode), UIO_USERSPACE);
}

int
do_sys_mkdir(const char *path, mode_t mode, enum uio_seg seg)
{
        struct proc *p = curlwp->l_proc;
        struct vnode *vp;
        struct vattr vattr;
        int error;
        struct nameidata nd;

        NDINIT(&nd, CREATE, LOCKPARENT | CREATEDIR | TRYEMULROOT,
            seg, path);
        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;
        /* We will read cwdi->cwdi_cmask unlocked. */
        vattr.va_mode = (mode & ACCESSPERMS) &~ p->p_cwdi->cwdi_cmask;
        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(struct lwp *l, const struct sys_rmdir_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */
        struct vnode *vp;
        int error;
        struct nameidata nd;

        NDINIT(&nd, DELETE, LOCKPARENT | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
            SCARG(uap, path));
        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_vflag & VV_ROOT) != 0 || vp->v_mountedhere != NULL) {
                error = EBUSY;
                goto out;
        }
        error = VOP_RMDIR(nd.ni_dvp, nd.ni_vp, &nd.ni_cnd);
        return (error);

out:
        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___getdents30(struct lwp *l, const struct sys___getdents30_args *uap, register_t *retval)
{
        /* {
                syscallarg(int) fd;
                syscallarg(char *) buf;
                syscallarg(size_t) count;
        } */
        file_t *fp;
        int error, done;

        /* fd_getvnode() will use the descriptor for us */
        if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
                return (error);
        if ((fp->f_flag & FREAD) == 0) {
                error = EBADF;
                goto out;
        }
        error = vn_readdir(fp, SCARG(uap, buf), UIO_USERSPACE,
                        SCARG(uap, count), &done, l, 0, 0);
        ktrgenio(SCARG(uap, fd), UIO_READ, SCARG(uap, buf), done, error);
        *retval = done;
 out:
        fd_putfile(SCARG(uap, fd));
        return (error);
}

/*
 * Set the mode mask for creation of filesystem nodes.
 */
int
sys_umask(struct lwp *l, const struct sys_umask_args *uap, register_t *retval)
{
        /* {
                syscallarg(mode_t) newmask;
        } */
        struct proc *p = l->l_proc;
        struct cwdinfo *cwdi;

        /*
         * cwdi->cwdi_cmask will be read unlocked elsewhere.  What's
         * important is that we serialize changes to the mask.  The
         * rw_exit() will issue a write memory barrier on our behalf,
         * and force the changes out to other CPUs (as it must use an
         * atomic operation, draining the local CPU's store buffers).
         */
        cwdi = p->p_cwdi;
        rw_enter(&cwdi->cwdi_lock, RW_WRITER);
        *retval = cwdi->cwdi_cmask;
        cwdi->cwdi_cmask = SCARG(uap, newmask) & ALLPERMS;
        rw_exit(&cwdi->cwdi_lock);

        return (0);
}

int
dorevoke(struct vnode *vp, kauth_cred_t cred)
{
        struct vattr vattr;
        int error;

        if ((error = VOP_GETATTR(vp, &vattr, cred)) != 0)
                return error;
        if (kauth_cred_geteuid(cred) == vattr.va_uid ||
            (error = kauth_authorize_generic(cred,
            KAUTH_GENERIC_ISSUSER, NULL)) == 0)
                VOP_REVOKE(vp, REVOKEALL);
        return (error);
}

/*
 * Void all references to file by ripping underlying filesystem
 * away from vnode.
 */
/* ARGSUSED */
int
sys_revoke(struct lwp *l, const struct sys_revoke_args *uap, register_t *retval)
{
        /* {
                syscallarg(const char *) path;
        } */
        struct vnode *vp;
        int error;

        error = namei_simple_user(SCARG(uap, path),
                                NSM_FOLLOW_TRYEMULROOT, &vp);
        if (error != 0)
                return (error);
        error = dorevoke(vp, l->l_cred);
        vrele(vp);
        return (error);
}