/*      $NetBSD: vfs_lookup.c,v 1.239 2025/09/14 14:24:13 andvar Exp $  */

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vfs_lookup.c        8.10 (Berkeley) 5/27/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.239 2025/09/14 14:24:13 andvar Exp $");

#ifdef _KERNEL_OPT
#include "opt_magiclinks.h"
#endif

#include <sys/param.h>
#include <sys/types.h>

#include <sys/dirent.h>
#include <sys/errno.h>
#include <sys/filedesc.h>
#include <sys/fstrans.h>
#include <sys/hash.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/ktrace.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/syslimits.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/vnode_impl.h>

#ifndef MAGICLINKS
#define MAGICLINKS 0
#endif

int vfs_magiclinks = MAGICLINKS;

__CTASSERT(MAXNAMLEN == NAME_MAX);

/*
 * Substitute replacement text for 'magic' strings in symlinks.
 * Returns 0 if successful, and returns non-zero if an error
 * occurs.  (Currently, the only possible error is running out
 * of temporary pathname space.)
 *
 * Looks for "@<string>" and "@<string>/", where <string> is a
 * recognized 'magic' string.  Replaces the "@<string>" with the
 * appropriate replacement text.  (Note that in some cases the
 * replacement text may have zero length.)
 *
 * This would have been table driven, but the variance in
 * replacement strings (and replacement string lengths) made
 * that impractical.
 */
#define VNL(x)                                                  \
        (sizeof(x) - 1)

#define VO      '{'
#define VC      '}'

#define MATCH(str)                                              \
        ((termchar == '/' && i + VNL(str) == *len) ||           \
         (i + VNL(str) < *len &&                                \
          cp[i + VNL(str)] == termchar)) &&                     \
        !strncmp((str), &cp[i], VNL(str))

#define SUBSTITUTE(m, s, sl)                                    \
        if ((newlen + (sl)) >= MAXPATHLEN)                      \
                return 1;                                       \
        i += VNL(m);                                            \
        if (termchar != '/')                                    \
                i++;                                            \
        (void)memcpy(&tmp[newlen], (s), (sl));                  \
        newlen += (sl);                                         \
        change = 1;                                             \
        termchar = '/';

static int
symlink_magic(struct proc *p, char *cp, size_t *len)
{
        char *tmp;
        size_t change, i, newlen, slen;
        char termchar = '/';
        char idtmp[11]; /* enough for 32 bit *unsigned* integer */


        tmp = PNBUF_GET();
        for (change = i = newlen = 0; i < *len; ) {
                if (cp[i] != '@') {
                        tmp[newlen++] = cp[i++];
                        continue;
                }

                i++;

                /* Check for @{var} syntax. */
                if (cp[i] == VO) {
                        termchar = VC;
                        i++;
                }

                /*
                 * The following checks should be ordered according
                 * to frequency of use.
                 */
                if (MATCH("machine_arch")) {
                        slen = strlen(PROC_MACHINE_ARCH(p));
                        SUBSTITUTE("machine_arch", PROC_MACHINE_ARCH(p), slen);
                } else if (MATCH("machine")) {
                        slen = VNL(MACHINE);
                        SUBSTITUTE("machine", MACHINE, slen);
                } else if (MATCH("hostname")) {
                        SUBSTITUTE("hostname", hostname, hostnamelen);
                } else if (MATCH("osrelease")) {
                        slen = strlen(osrelease);
                        SUBSTITUTE("osrelease", osrelease, slen);
                } else if (MATCH("emul")) {
                        slen = strlen(p->p_emul->e_name);
                        SUBSTITUTE("emul", p->p_emul->e_name, slen);
                } else if (MATCH("kernel_ident")) {
                        slen = strlen(kernel_ident);
                        SUBSTITUTE("kernel_ident", kernel_ident, slen);
                } else if (MATCH("domainname")) {
                        SUBSTITUTE("domainname", domainname, domainnamelen);
                } else if (MATCH("ostype")) {
                        slen = strlen(ostype);
                        SUBSTITUTE("ostype", ostype, slen);
                } else if (MATCH("uid")) {
                        slen = snprintf(idtmp, sizeof(idtmp), "%u",
                            kauth_cred_geteuid(kauth_cred_get()));
                        SUBSTITUTE("uid", idtmp, slen);
                } else if (MATCH("ruid")) {
                        slen = snprintf(idtmp, sizeof(idtmp), "%u",
                            kauth_cred_getuid(kauth_cred_get()));
                        SUBSTITUTE("ruid", idtmp, slen);
                } else if (MATCH("gid")) {
                        slen = snprintf(idtmp, sizeof(idtmp), "%u",
                            kauth_cred_getegid(kauth_cred_get()));
                        SUBSTITUTE("gid", idtmp, slen);
                } else if (MATCH("rgid")) {
                        slen = snprintf(idtmp, sizeof(idtmp), "%u",
                            kauth_cred_getgid(kauth_cred_get()));
                        SUBSTITUTE("rgid", idtmp, slen);
                } else {
                        tmp[newlen++] = '@';
                        if (termchar == VC)
                                tmp[newlen++] = VO;
                }
        }

        if (change) {
                (void)memcpy(cp, tmp, newlen);
                *len = newlen;
        }
        PNBUF_PUT(tmp);

        return 0;
}

#undef VNL
#undef VO
#undef VC
#undef MATCH
#undef SUBSTITUTE

////////////////////////////////////////////////////////////

/*
 * Determine the namei hash (for the namecache) for name.
 * If *ep != NULL, hash from name to ep-1.
 * If *ep == NULL, hash from name until the first NUL or '/', and
 * return the location of this termination character in *ep.
 *
 * This function returns an equivalent hash to the MI hash32_strn().
 * The latter isn't used because in the *ep == NULL case, determining
 * the length of the string to the first NUL or `/' and then calling
 * hash32_strn() involves unnecessary double-handling of the data.
 */
uint32_t
namei_hash(const char *name, const char **ep)
{
        uint32_t        hash;

        hash = HASH32_STR_INIT;
        if (*ep != NULL) {
                for (; name < *ep; name++)
                        hash = hash * 33 + *(const uint8_t *)name;
        } else {
                for (; *name != '\0' && *name != '/'; name++)
                        hash = hash * 33 + *(const uint8_t *)name;
                *ep = name;
        }
        return (hash + (hash >> 5));
}

////////////////////////////////////////////////////////////

/*
 * Sealed abstraction for pathnames.
 *
 * System-call-layer level code that is going to call namei should
 * first create a pathbuf and adjust all the bells and whistles on it
 * as needed by context.
 */

struct pathbuf {
        char *pb_path;
        char *pb_pathcopy;
        unsigned pb_pathcopyuses;
};

static struct pathbuf *
pathbuf_create_raw(void)
{
        struct pathbuf *pb;

        pb = kmem_alloc(sizeof(*pb), KM_SLEEP);
        pb->pb_path = PNBUF_GET();
        if (pb->pb_path == NULL) {
                kmem_free(pb, sizeof(*pb));
                return NULL;
        }
        pb->pb_pathcopy = NULL;
        pb->pb_pathcopyuses = 0;
        return pb;
}

void
pathbuf_destroy(struct pathbuf *pb)
{

        KASSERT(pb->pb_pathcopyuses == 0);
        KASSERT(pb->pb_pathcopy == NULL);
        PNBUF_PUT(pb->pb_path);
        kmem_free(pb, sizeof(*pb));
}

struct pathbuf *
pathbuf_assimilate(char *pnbuf)
{
        struct pathbuf *pb;

        pb = kmem_alloc(sizeof(*pb), KM_SLEEP);
        pb->pb_path = pnbuf;
        pb->pb_pathcopy = NULL;
        pb->pb_pathcopyuses = 0;
        return pb;
}

struct pathbuf *
pathbuf_create(const char *path)
{
        struct pathbuf *pb;
        int error;

        pb = pathbuf_create_raw();
        if (pb == NULL) {
                return NULL;
        }
        error = copystr(path, pb->pb_path, PATH_MAX, NULL);
        if (error != 0) {
                KASSERT(!"kernel path too long in pathbuf_create");
                /* make sure it's null-terminated, just in case */
                pb->pb_path[PATH_MAX-1] = '\0';
        }
        return pb;
}

int
pathbuf_copyin(const char *userpath, struct pathbuf **ret)
{
        struct pathbuf *pb;
        int error;

        pb = pathbuf_create_raw();
        if (pb == NULL) {
                return SET_ERROR(ENOMEM);
        }
        error = copyinstr(userpath, pb->pb_path, PATH_MAX, NULL);
        if (error) {
                pathbuf_destroy(pb);
                return error;
        }
        *ret = pb;
        return 0;
}

/*
 * XXX should not exist:
 *   1. whether a pointer is kernel or user should be statically checkable.
 *   2. copyin should be handled by the upper part of the syscall layer,
 *      not in here.
 */
int
pathbuf_maybe_copyin(const char *path, enum uio_seg seg, struct pathbuf **ret)
{

        if (seg == UIO_USERSPACE) {
                return pathbuf_copyin(path, ret);
        } else {
                *ret = pathbuf_create(path);
                if (*ret == NULL) {
                        return SET_ERROR(ENOMEM);
                }
                return 0;
        }
}

/*
 * Get a copy of the path buffer as it currently exists. If this is
 * called after namei starts the results may be arbitrary.
 */
void
pathbuf_copystring(const struct pathbuf *pb, char *buf, size_t maxlen)
{

        strlcpy(buf, pb->pb_path, maxlen);
}

/*
 * These two functions allow access to a saved copy of the original
 * path string. The first copy should be gotten before namei is
 * called. Each copy that is gotten should be put back.
 */

const char *
pathbuf_stringcopy_get(struct pathbuf *pb)
{

        if (pb->pb_pathcopyuses == 0) {
                pb->pb_pathcopy = PNBUF_GET();
                strcpy(pb->pb_pathcopy, pb->pb_path);
        }
        pb->pb_pathcopyuses++;
        return pb->pb_pathcopy;
}

void
pathbuf_stringcopy_put(struct pathbuf *pb, const char *str)
{

        KASSERT(str == pb->pb_pathcopy);
        KASSERT(pb->pb_pathcopyuses > 0);
        pb->pb_pathcopyuses--;
        if (pb->pb_pathcopyuses == 0) {
                PNBUF_PUT(pb->pb_pathcopy);
                pb->pb_pathcopy = NULL;
        }
}


////////////////////////////////////////////////////////////

/*
 * namei: convert a pathname into a pointer to a (maybe-locked) vnode,
 * and maybe also its parent directory vnode, and assorted other guff.
 * See namei(9) for the interface documentation.
 *
 *
 * The FOLLOW flag is set when symbolic links are to be followed
 * when they occur at the end of the name translation process.
 * Symbolic links are always followed for all other pathname
 * components other than the last.
 *
 * The segflg defines whether the name is to be copied from user
 * space or kernel space.
 *
 * Overall outline of namei:
 *
 *      copy in name
 *      get starting directory
 *      while (!done && !error) {
 *              call lookup to search path.
 *              if symbolic link, massage name in buffer and continue
 *      }
 */

/*
 * Search a pathname.
 * This is a very central and rather complicated routine.
 *
 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
 * The starting directory is passed in. The pathname is descended
 * until done, or a symbolic link is encountered. The variable ni_more
 * is clear if the path is completed; it is set to one if a symbolic
 * link needing interpretation is encountered.
 *
 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
 * whether the name is to be looked up, created, renamed, or deleted.
 * When CREATE, RENAME, or DELETE is specified, information usable in
 * creating, renaming, or deleting a directory entry may be calculated.
 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
 * locked.  Otherwise the parent directory is not returned. If the target
 * of the pathname exists and LOCKLEAF is or'ed into the flag the target
 * is returned locked, otherwise it is returned unlocked.  When creating
 * or renaming and LOCKPARENT is specified, the target may not be ".".
 * When deleting and LOCKPARENT is specified, the target may be ".".
 *
 * Overall outline of lookup:
 *
 * dirloop:
 *      identify next component of name at ndp->ni_ptr
 *      handle degenerate case where name is null string
 *      if .. and crossing mount points and on mounted filesys, find parent
 *      call VOP_LOOKUP routine for next component name
 *          directory vnode returned in ni_dvp, locked.
 *          component vnode returned in ni_vp (if it exists), locked.
 *      if result vnode is mounted on and crossing mount points,
 *          find mounted on vnode
 *      if more components of name, do next level at dirloop
 *      return the answer in ni_vp, locked if LOCKLEAF set
 *          if LOCKPARENT set, return locked parent in ni_dvp
 */


/*
 * Internal state for a namei operation.
 *
 * cnp is always equal to &ndp->ni_cnp.
 */
struct namei_state {
        struct nameidata *ndp;
        struct componentname *cnp;

        int docache;                    /* == 0 do not cache last component */
        int rdonly;                     /* lookup read-only flag bit */
        int slashes;

        unsigned attempt_retry:1;       /* true if error allows emul retry */
        unsigned root_referenced:1;     /* true if ndp->ni_rootdir and
                                            ndp->ni_erootdir were referenced */
};


/*
 * Initialize the namei working state.
 */
static void
namei_init(struct namei_state *state, struct nameidata *ndp)
{

        state->ndp = ndp;
        state->cnp = &ndp->ni_cnd;

        state->docache = 0;
        state->rdonly = 0;
        state->slashes = 0;

        state->root_referenced = 0;

        KASSERTMSG((state->cnp->cn_cred != NULL), "namei: bad cred/proc");
        KASSERTMSG(((state->cnp->cn_nameiop & (~OPMASK)) == 0),
            "namei: nameiop contaminated with flags: %08"PRIx32,
            state->cnp->cn_nameiop);
        KASSERTMSG(((state->cnp->cn_flags & OPMASK) == 0),
            "name: flags contaminated with nameiops: %08"PRIx32,
            state->cnp->cn_flags);

        /*
         * The buffer for name translation shall be the one inside the
         * pathbuf.
         */
        state->ndp->ni_pnbuf = state->ndp->ni_pathbuf->pb_path;
}

/*
 * Clean up the working namei state, leaving things ready for return
 * from namei.
 */
static void
namei_cleanup(struct namei_state *state)
{

        KASSERT(state->cnp == &state->ndp->ni_cnd);

        if (state->root_referenced) {
                if (state->ndp->ni_rootdir != NULL)
                        vrele(state->ndp->ni_rootdir);
                if (state->ndp->ni_erootdir != NULL)
                        vrele(state->ndp->ni_erootdir);
        }
}

//////////////////////////////

/*
 * Get the directory context.
 * Initializes the rootdir and erootdir state and returns a reference
 * to the starting dir.
 */
static struct vnode *
namei_getstartdir(struct namei_state *state)
{
        struct nameidata *ndp = state->ndp;
        struct componentname *cnp = state->cnp;
        struct cwdinfo *cwdi;           /* pointer to cwd state */
        struct lwp *self = curlwp;      /* thread doing namei() */
        struct vnode *rootdir, *erootdir, *curdir, *startdir;

        if (state->root_referenced) {
                if (state->ndp->ni_rootdir != NULL)
                        vrele(state->ndp->ni_rootdir);
                if (state->ndp->ni_erootdir != NULL)
                        vrele(state->ndp->ni_erootdir);
                state->root_referenced = 0;
        }

        cwdi = self->l_proc->p_cwdi;
        rw_enter(&cwdi->cwdi_lock, RW_READER);

        /* root dir */
        if (cwdi->cwdi_rdir == NULL || (cnp->cn_flags & NOCHROOT)) {
                rootdir = rootvnode;
        } else {
                rootdir = cwdi->cwdi_rdir;
        }

        /* emulation root dir, if any */
        if ((cnp->cn_flags & TRYEMULROOT) == 0) {
                /* if we don't want it, don't fetch it */
                erootdir = NULL;
        } else if (cnp->cn_flags & EMULROOTSET) {
                /* explicitly set emulroot; "/../" doesn't override this */
                erootdir = ndp->ni_erootdir;
        } else if (!strncmp(ndp->ni_pnbuf, "/../", 4)) {
                /* explicit reference to real rootdir */
                erootdir = NULL;
        } else {
                /* may be null */
                erootdir = cwdi->cwdi_edir;
        }

        /* current dir */
        curdir = cwdi->cwdi_cdir;

        if (ndp->ni_pnbuf[0] != '/') {
                if (ndp->ni_atdir != NULL) {
                        startdir = ndp->ni_atdir;
                } else {
                        startdir = curdir;
                }
                erootdir = NULL;
        } else if (cnp->cn_flags & TRYEMULROOT && erootdir != NULL) {
                startdir = erootdir;
        } else {
                startdir = rootdir;
                erootdir = NULL;
        }

        state->ndp->ni_rootdir = rootdir;
        state->ndp->ni_erootdir = erootdir;

        /*
         * Get a reference to the start dir so we can safely unlock cwdi.
         *
         * Must hold references to rootdir and erootdir while we're running.
         * A multithreaded process may chroot during namei.
         */
        if (startdir != NULL)
                vref(startdir);
        if (state->ndp->ni_rootdir != NULL)
                vref(state->ndp->ni_rootdir);
        if (state->ndp->ni_erootdir != NULL)
                vref(state->ndp->ni_erootdir);
        state->root_referenced = 1;

        rw_exit(&cwdi->cwdi_lock);
        return startdir;
}

/*
 * Get the directory context for the nfsd case, in parallel to
 * getstartdir. Initializes the rootdir and erootdir state and
 * returns a reference to the passed-in starting dir.
 */
static struct vnode *
namei_getstartdir_for_nfsd(struct namei_state *state)
{

        KASSERT(state->ndp->ni_atdir != NULL);

        /* always use the real root, and never set an emulation root */
        if (rootvnode == NULL) {
                return NULL;
        }
        state->ndp->ni_rootdir = rootvnode;
        state->ndp->ni_erootdir = NULL;

        vref(state->ndp->ni_atdir);
        KASSERT(! state->root_referenced);
        vref(state->ndp->ni_rootdir);
        state->root_referenced = 1;
        return state->ndp->ni_atdir;
}


/*
 * Ktrace the namei operation.
 */
static void
namei_ktrace(struct namei_state *state)
{
        struct nameidata *ndp = state->ndp;
        struct componentname *cnp = state->cnp;
        struct lwp *self = curlwp;      /* thread doing namei() */
        const char *emul_path;

        if (ktrpoint(KTR_NAMEI)) {
                if (ndp->ni_erootdir != NULL) {
                        /*
                         * To make any sense, the trace entry need to have the
                         * text of the emulation path prepended.
                         * Usually we can get this from the current process,
                         * but when called from emul_find_interp() it is only
                         * in the exec_package - so we get it passed in ni_next
                         * (this is a hack).
                         */
                        if (cnp->cn_flags & EMULROOTSET)
                                emul_path = ndp->ni_next;
                        else
                                emul_path = self->l_proc->p_emul->e_path;
                        ktrnamei2(emul_path, strlen(emul_path),
                            ndp->ni_pnbuf, ndp->ni_pathlen);
                } else
                        ktrnamei(ndp->ni_pnbuf, ndp->ni_pathlen);
        }
}

/*
 * Start up namei. Find the root dir and cwd, establish the starting
 * directory for lookup, and lock it. Also calls ktrace when
 * appropriate.
 */
static int
namei_start(struct namei_state *state, int isnfsd,
    struct vnode **startdir_ret)
{
        struct nameidata *ndp = state->ndp;
        struct vnode *startdir;

        /* length includes null terminator (was originally from copyinstr) */
        ndp->ni_pathlen = strlen(ndp->ni_pnbuf) + 1;

        /*
         * POSIX.1 requirement: "" is not a valid file name.
         */
        if (ndp->ni_pathlen == 1) {
                ndp->ni_erootdir = NULL;
                return SET_ERROR(ENOENT);
        }

        ndp->ni_loopcnt = 0;

        /* Get starting directory, set up root, and ktrace. */
        if (isnfsd) {
                startdir = namei_getstartdir_for_nfsd(state);
                /* no ktrace */
        } else {
                startdir = namei_getstartdir(state);
                namei_ktrace(state);
        }

        if (startdir == NULL) {
                return SET_ERROR(ENOENT);
        }

        /* NDAT may feed us with a non directory namei_getstartdir */
        if (startdir->v_type != VDIR) {
                vrele(startdir);
                return SET_ERROR(ENOTDIR);
        }

        *startdir_ret = startdir;
        return 0;
}

/*
 * Check for being at a symlink that we're going to follow.
 */
static inline int
namei_atsymlink(struct namei_state *state, struct vnode *foundobj)
{

        return (foundobj->v_type == VLNK) &&
            (state->cnp->cn_flags & (FOLLOW|REQUIREDIR));
}

/*
 * Follow a symlink.
 *
 * Updates searchdir. inhibitmagic causes magic symlinks to not be
 * interpreted; this is used by nfsd.
 *
 * Unlocks foundobj on success (ugh)
 */
static inline int
namei_follow(struct namei_state *state, int inhibitmagic,
    struct vnode *searchdir, struct vnode *foundobj,
    struct vnode **newsearchdir_ret)
{
        struct nameidata *ndp = state->ndp;
        struct componentname *cnp = state->cnp;

        struct lwp *self = curlwp;      /* thread doing namei() */
        struct iovec aiov;              /* uio for reading symbolic links */
        struct uio auio;
        char *cp;                       /* pointer into pathname argument */
        size_t linklen;
        int error;

        if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
                return SET_ERROR(ELOOP);
        }

        vn_lock(foundobj, LK_EXCLUSIVE | LK_RETRY);
        if (foundobj->v_mount->mnt_flag & MNT_SYMPERM) {
                error = VOP_ACCESS(foundobj, VEXEC, cnp->cn_cred);
                if (error != 0) {
                        VOP_UNLOCK(foundobj);
                        return error;
                }
        }

        /* FUTURE: fix this to not use a second buffer */
        cp = PNBUF_GET();
        aiov.iov_base = cp;
        aiov.iov_len = MAXPATHLEN;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_offset = 0;
        auio.uio_rw = UIO_READ;
        auio.uio_resid = MAXPATHLEN;
        UIO_SETUP_SYSSPACE(&auio);
        error = VOP_READLINK(foundobj, &auio, cnp->cn_cred);
        VOP_UNLOCK(foundobj);
        if (error) {
                PNBUF_PUT(cp);
                return error;
        }
        linklen = MAXPATHLEN - auio.uio_resid;
        if (linklen == 0) {
                PNBUF_PUT(cp);
                return SET_ERROR(ENOENT);
        }

        /*
         * Do symlink substitution, if appropriate, and
         * check length for potential overflow.
         *
         * Inhibit symlink substitution for nfsd.
         * XXX: This is how it was before; is that a bug or a feature?
         */
        if ((!inhibitmagic && vfs_magiclinks &&
                symlink_magic(self->l_proc, cp, &linklen)) ||
            (linklen + ndp->ni_pathlen >= MAXPATHLEN)) {
                PNBUF_PUT(cp);
                return SET_ERROR(ENAMETOOLONG);
        }
        if (ndp->ni_pathlen > 1) {
                /* includes a null-terminator */
                memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen);
        } else {
                cp[linklen] = '\0';
        }
        ndp->ni_pathlen += linklen;
        memcpy(ndp->ni_pnbuf, cp, ndp->ni_pathlen);
        PNBUF_PUT(cp);

        /* we're now starting from the beginning of the buffer again */
        cnp->cn_nameptr = ndp->ni_pnbuf;

        /*
         * Check if root directory should replace current directory.
         */
        if (ndp->ni_pnbuf[0] == '/') {
                vrele(searchdir);
                /* Keep absolute symbolic links inside emulation root */
                searchdir = ndp->ni_erootdir;
                if (searchdir == NULL ||
                    (ndp->ni_pnbuf[1] == '.'
                        && ndp->ni_pnbuf[2] == '.'
                        && ndp->ni_pnbuf[3] == '/')) {
                        ndp->ni_erootdir = NULL;
                        searchdir = ndp->ni_rootdir;
                }
                vref(searchdir);
                while (cnp->cn_nameptr[0] == '/') {
                        cnp->cn_nameptr++;
                        ndp->ni_pathlen--;
                }
        }

        *newsearchdir_ret = searchdir;
        return 0;
}

//////////////////////////////

/*
 * Inspect the leading path component and update the state accordingly.
 */
static int
lookup_parsepath(struct namei_state *state, struct vnode *searchdir)
{
        const char *cp;                 /* pointer into pathname argument */
        int error;
        struct componentname *cnp = state->cnp;
        struct nameidata *ndp = state->ndp;

        KASSERT(cnp == &ndp->ni_cnd);

        /*
         * Search a new directory.
         *
         * The last component of the filename is left accessible via
         * cnp->cn_nameptr for callers that need the name. Callers needing
         * the name set the SAVENAME flag. When done, they assume
         * responsibility for freeing the pathname buffer.
         *
         * At this point, our only vnode state is that the search dir
         * is held.
         */
        error = VOP_PARSEPATH(searchdir, cnp->cn_nameptr, &cnp->cn_namelen);
        if (error) {
                return error;
        }
        cp = cnp->cn_nameptr + cnp->cn_namelen;
        if (cnp->cn_namelen > KERNEL_NAME_MAX) {
                return SET_ERROR(ENAMETOOLONG);
        }
#ifdef NAMEI_DIAGNOSTIC
        { char c = *cp;
                *(char *)cp = '\0';
                printf("{%s}: ", cnp->cn_nameptr);
                *(char *)cp = c; }
#endif /* NAMEI_DIAGNOSTIC */
        ndp->ni_pathlen -= cnp->cn_namelen;
        ndp->ni_next = cp;
        /*
         * If this component is followed by a slash, then move the pointer to
         * the next component forward, and remember that this component must be
         * a directory.
         */
        if (*cp == '/') {
                do {
                        cp++;
                } while (*cp == '/');
                state->slashes = cp - ndp->ni_next;
                ndp->ni_pathlen -= state->slashes;
                ndp->ni_next = cp;
                cnp->cn_flags |= REQUIREDIR;
        } else {
                state->slashes = 0;
                cnp->cn_flags &= ~REQUIREDIR;
        }
        /*
         * We do special processing on the last component, whether or not it's
         * a directory.  Cache all intervening lookups, but not the final one.
         */
        if (*cp == '\0') {
                if (state->docache)
                        cnp->cn_flags |= MAKEENTRY;
                else
                        cnp->cn_flags &= ~MAKEENTRY;
                cnp->cn_flags |= ISLASTCN;
        } else {
                cnp->cn_flags |= MAKEENTRY;
                cnp->cn_flags &= ~ISLASTCN;
        }
        if (cnp->cn_namelen == 2 &&
            cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
                cnp->cn_flags |= ISDOTDOT;
        else
                cnp->cn_flags &= ~ISDOTDOT;

        return 0;
}

/*
 * Take care of crossing a mounted-on vnode.  On error, foundobj_ret will be
 * vrele'd, but searchdir is left alone.
 */
static int
lookup_crossmount(struct namei_state *state,
    struct vnode **searchdir_ret,
    struct vnode **foundobj_ret,
    bool *searchdir_locked)
{
        struct componentname *cnp = state->cnp;
        struct vnode *foundobj, *vp;
        struct vnode *searchdir;
        struct mount *mp;
        int error, lktype;

        searchdir = *searchdir_ret;
        foundobj = *foundobj_ret;
        error = 0;

        KASSERT((cnp->cn_flags & NOCROSSMOUNT) == 0);

        /* First, unlock searchdir (oof). */
        if (*searchdir_locked) {
                KASSERT(searchdir != NULL);
                lktype = VOP_ISLOCKED(searchdir);
                VOP_UNLOCK(searchdir);
                *searchdir_locked = false;
        } else {
                lktype = LK_NONE;
        }

        /*
         * Do an unlocked check to see if the vnode has been mounted on; if
         * so find the root of the mounted file system.
         */
        while (foundobj->v_type == VDIR &&
            (mp = foundobj->v_mountedhere) != NULL &&
            (cnp->cn_flags & NOCROSSMOUNT) == 0) {
                /*
                 * Try the namecache first.  If that doesn't work, do
                 * it the hard way.
                 */
                if (cache_lookup_mount(foundobj, &vp)) {
                        vrele(foundobj);
                        foundobj = vp;
                } else {
                        /* First get the vnodes mount stable. */
                        while ((mp = foundobj->v_mountedhere) != NULL) {
                                fstrans_start(mp);
                                if (fstrans_held(mp) &&
                                    mp == foundobj->v_mountedhere) {
                                        break;
                                }
                                fstrans_done(mp);
                        }
                        if (mp == NULL) {
                                break;
                        }

                        /*
                         * Now get a reference on the root vnode.
                         * XXX Future - maybe allow only VDIR here.
                         */
                        error = VFS_ROOT(mp, LK_NONE, &vp);

                        /*
                         * If successful, enter it into the cache while
                         * holding the mount busy (competing with unmount).
                         */
                        if (error == 0) {
                                cache_enter_mount(foundobj, vp);
                        }

                        /*
                         * Finally, drop references to foundobj & mountpoint.
                         */
                        vrele(foundobj);
                        fstrans_done(mp);
                        if (error) {
                                foundobj = NULL;
                                break;
                        }
                        foundobj = vp;
                }

                /*
                 * Avoid locking vnodes from two filesystems because
                 * it's prone to deadlock, e.g. when using puffs.
                 * Also, it isn't a good idea to propagate slowness of
                 * a filesystem up to the root directory. For now,
                 * only handle the common case, where foundobj is
                 * VDIR.
                 *
                 * In this case set searchdir to null to avoid using
                 * it again. It is not correct to set searchdir ==
                 * foundobj here as that will confuse the caller.
                 * (See PR 40740.)
                 */
                if (searchdir == NULL) {
                        /* already been here once; do nothing further */
                } else if (foundobj->v_type == VDIR) {
                        vrele(searchdir);
                        *searchdir_ret = searchdir = NULL;
                        lktype = LK_NONE;
                }
        }

        /* If searchdir is still around, re-lock it. */
        if (error == 0 && lktype != LK_NONE) {
                vn_lock(searchdir, lktype | LK_RETRY);
                *searchdir_locked = true;
        }
        *foundobj_ret = foundobj;
        return error;
}

/*
 * Determine the desired locking mode for the directory of a lookup.
 */
static int
lookup_lktype(struct vnode *searchdir, struct componentname *cnp)
{

        /*
         * If the file system supports VOP_LOOKUP() with a shared lock, and
         * we are not making any modifications (nameiop LOOKUP) or this is
         * not the last component then get a shared lock.  Where we can't do
         * fast-forwarded lookups (for example with layered file systems)
         * then this is the fallback for reducing lock contention.
         */
        if ((searchdir->v_mount->mnt_iflag & IMNT_SHRLOOKUP) != 0 &&
            (cnp->cn_nameiop == LOOKUP || (cnp->cn_flags & ISLASTCN) == 0)) {
                return LK_SHARED;
        } else {
                return LK_EXCLUSIVE;
        }
}

/*
 * Call VOP_LOOKUP for a single lookup; return a new search directory
 * (used when crossing mountpoints up or searching union mounts down) and
 * the found object, which for create operations may be NULL on success.
 *
 * Note that the new search directory may be null, which means the
 * searchdir was unlocked and released. This happens in the common case
 * when crossing a mount point downwards, in order to avoid coupling
 * locks between different file system volumes. Importantly, this can
 * happen even if the call fails. (XXX: this is gross and should be
 * tidied somehow.)
 */
static int
lookup_once(struct namei_state *state,
    struct vnode *searchdir,
    struct vnode **newsearchdir_ret,
    struct vnode **foundobj_ret,
    bool *newsearchdir_locked_ret)
{
        struct vnode *tmpvn;            /* scratch vnode */
        struct vnode *foundobj;         /* result */
        struct lwp *l = curlwp;
        bool searchdir_locked = false;
        int error, lktype;

        struct componentname *cnp = state->cnp;
        struct nameidata *ndp = state->ndp;

        KASSERT(cnp == &ndp->ni_cnd);
        *newsearchdir_ret = searchdir;

        /*
         * Handle "..": two special cases.
         * 1. If at root directory (e.g. after chroot)
         *    or at absolute root directory
         *    then ignore it so can't get out.
         * 1a. If at the root of the emulation filesystem go to the real
         *    root. So "/../<path>" is always absolute.
         * 1b. If we have somehow gotten out of a jail, warn
         *    and also ignore it so we can't get farther out.
         * 2. If this vnode is the root of a mounted
         *    filesystem, then replace it with the
         *    vnode which was mounted on so we take the
         *    .. in the other file system.
         */
        if (cnp->cn_flags & ISDOTDOT) {
                struct proc *p = l->l_proc;

                for (;;) {
                        if (searchdir == ndp->ni_rootdir ||
                            searchdir == rootvnode) {
                                foundobj = searchdir;
                                vref(foundobj);
                                *foundobj_ret = foundobj;
                                if (cnp->cn_flags & LOCKPARENT) {
                                        lktype = lookup_lktype(searchdir, cnp);
                                        vn_lock(searchdir, lktype | LK_RETRY);
                                        searchdir_locked = true;
                                }
                                error = 0;
                                goto done;
                        }
                        if (ndp->ni_rootdir != rootvnode) {
                                int retval;

                                retval = vn_isunder(searchdir, ndp->ni_rootdir,
                                    l);
                                if (!retval) {
                                        /* Oops! We got out of jail! */
                                        log(LOG_WARNING,
                                            "chrooted pid %d uid %d (%s) "
                                            "detected outside of its chroot\n",
                                            p->p_pid,
                                            kauth_cred_geteuid(l->l_cred),
                                            p->p_comm);
                                        /* Put us at the jail root. */
                                        vrele(searchdir);
                                        searchdir = NULL;
                                        foundobj = ndp->ni_rootdir;
                                        vref(foundobj);
                                        vref(foundobj);
                                        *newsearchdir_ret = foundobj;
                                        *foundobj_ret = foundobj;
                                        error = 0;
                                        goto done;
                                }
                        }
                        if ((searchdir->v_vflag & VV_ROOT) == 0 ||
                            (cnp->cn_flags & NOCROSSMOUNT))
                                break;
                        tmpvn = searchdir;
                        searchdir = searchdir->v_mount->mnt_vnodecovered;
                        vref(searchdir);
                        vrele(tmpvn);
                        *newsearchdir_ret = searchdir;
                }
        }

        lktype = lookup_lktype(searchdir, cnp);

        /*
         * We now have a segment name to search for, and a directory to search.
         * Our vnode state here is that "searchdir" is held.
         */
unionlookup:
        foundobj = NULL;
        if (!searchdir_locked) {
                vn_lock(searchdir, lktype | LK_RETRY);
                searchdir_locked = true;
        }
        error = VOP_LOOKUP(searchdir, &foundobj, cnp);

        if (error != 0) {
                KASSERTMSG((foundobj == NULL),
                    "leaf `%s' should be empty but is %p",
                    cnp->cn_nameptr, foundobj);
#ifdef NAMEI_DIAGNOSTIC
                printf("not found\n");
#endif /* NAMEI_DIAGNOSTIC */

                /*
                 * If ENOLCK, the file system needs us to retry the lookup
                 * with an exclusive lock.  It's likely nothing was found in
                 * cache and/or modifications need to be made.
                 */
                if (error == ENOLCK) {
                        KASSERT(VOP_ISLOCKED(searchdir) == LK_SHARED);
                        KASSERT(searchdir_locked);
                        if (vn_lock(searchdir, LK_UPGRADE | LK_NOWAIT)) {
                                VOP_UNLOCK(searchdir);
                                searchdir_locked = false;
                        }
                        lktype = LK_EXCLUSIVE;
                        goto unionlookup;
                }

                if ((error == ENOENT) &&
                    (searchdir->v_vflag & VV_ROOT) &&
                    (searchdir->v_mount->mnt_flag & MNT_UNION)) {
                        tmpvn = searchdir;
                        searchdir = searchdir->v_mount->mnt_vnodecovered;
                        vref(searchdir);
                        vput(tmpvn);
                        searchdir_locked = false;
                        *newsearchdir_ret = searchdir;
                        goto unionlookup;
                }

                if (error != EJUSTRETURN)
                        goto done;

                /*
                 * If this was not the last component, or there were trailing
                 * slashes, and we are not going to create a directory,
                 * then the name must exist.
                 */
                if ((cnp->cn_flags & (REQUIREDIR | CREATEDIR)) == REQUIREDIR) {
                        error = SET_ERROR(ENOENT);
                        goto done;
                }

                /*
                 * If creating and at end of pathname, then can consider
                 * allowing file to be created.
                 */
                if (state->rdonly) {
                        error = SET_ERROR(EROFS);
                        goto done;
                }

                /*
                 * We return success and a NULL foundobj to indicate
                 * that the entry doesn't currently exist, leaving a
                 * pointer to the (normally, locked) directory vnode
                 * as searchdir.
                 */
                *foundobj_ret = NULL;
                error = 0;
                goto done;
        }
#ifdef NAMEI_DIAGNOSTIC
        printf("found\n");
#endif /* NAMEI_DIAGNOSTIC */

        /* Unlock, unless the caller needs the parent locked. */
        if (searchdir != NULL) {
                KASSERT(searchdir_locked);
                if ((cnp->cn_flags & (ISLASTCN | LOCKPARENT)) !=
                    (ISLASTCN | LOCKPARENT)) {
                        VOP_UNLOCK(searchdir);
                        searchdir_locked = false;
                }
        } else {
                KASSERT(!searchdir_locked);
        }

        *foundobj_ret = foundobj;
        error = 0;
done:
        *newsearchdir_locked_ret = searchdir_locked;
        return error;
}

/*
 * Parse out the first path name component that we need to to consider.
 *
 * While doing this, attempt to use the name cache to fast-forward through
 * as many "easy" to find components of the path as possible.
 *
 * We use the namecache's node locks to form a chain, and avoid as many
 * vnode references and locks as possible.  In the ideal case, only the
 * final vnode will have its reference count adjusted and lock taken.
 */
static int
lookup_fastforward(struct namei_state *state, struct vnode **searchdir_ret,
    struct vnode **foundobj_ret)
{
        struct componentname *cnp = state->cnp;
        struct nameidata *ndp = state->ndp;
        krwlock_t *plock;
        struct vnode *foundobj, *searchdir;
        int error, error2;
        size_t oldpathlen;
        const char *oldnameptr;
        bool terminal;

        /*
         * Eat as many path name components as possible before giving up and
         * letting lookup_once() handle it.  Remember the starting point in
         * case we can't get vnode references and need to roll back.
         */
        plock = NULL;
        searchdir = *searchdir_ret;
        oldnameptr = cnp->cn_nameptr;
        oldpathlen = ndp->ni_pathlen;
        terminal = false;
        for (;;) {
                foundobj = NULL;

                /*
                 * Get the next component name.  There should be no slashes
                 * here, and we shouldn't have looped around if we were
                 * done.
                 */
                KASSERT(cnp->cn_nameptr[0] != '/');
                KASSERT(cnp->cn_nameptr[0] != '\0');
                if ((error = lookup_parsepath(state, searchdir)) != 0) {
                        break;
                }

                /*
                 * Can't deal with DOTDOT lookups if NOCROSSMOUNT or the
                 * lookup is chrooted.
                 */
                if ((cnp->cn_flags & ISDOTDOT) != 0) {
                        if ((searchdir->v_vflag & VV_ROOT) != 0 &&
                            (cnp->cn_flags & NOCROSSMOUNT)) {
                                error = SET_ERROR(EOPNOTSUPP);
                                break;
                        }
                        if (ndp->ni_rootdir != rootvnode) {
                                error = SET_ERROR(EOPNOTSUPP);
                                break;
                        }
                }

                /*
                 * Can't deal with last component when modifying; this needs
                 * searchdir locked and VOP_LOOKUP() called (which can and
                 * does modify state, despite the name).  NB: this case means
                 * terminal is never set true when LOCKPARENT.
                 */
                if ((cnp->cn_flags & ISLASTCN) != 0) {
                        if (cnp->cn_nameiop != LOOKUP ||
                            (cnp->cn_flags & LOCKPARENT) != 0) {
                                error = SET_ERROR(EOPNOTSUPP);
                                break;
                        }
                }

                /*
                 * Good, now look for it in cache.  cache_lookup_linked()
                 * will fail if there's nothing there, or if there's no
                 * ownership info for the directory, or if the user doesn't
                 * have permission to look up files in this directory.
                 */
                if (!cache_lookup_linked(searchdir, cnp->cn_nameptr,
                        cnp->cn_namelen, &foundobj, &plock, cnp->cn_cred)) {
                        error = SET_ERROR(EOPNOTSUPP);
                        break;
                }
                KASSERT(plock != NULL);
                KASSERT(rw_lock_held(plock));

                /*
                 * Scored a hit.  Negative is good too (ENOENT).  If there's
                 * a '-o union' mount here, punt and let lookup_once() deal
                 * with it.
                 */
                if (foundobj == NULL) {
                        if ((searchdir->v_vflag & VV_ROOT) != 0 &&
                            (searchdir->v_mount->mnt_flag & MNT_UNION) != 0) {
                                error = SET_ERROR(EOPNOTSUPP);
                        } else {
                                error = SET_ERROR(ENOENT);
                                terminal = ((cnp->cn_flags & ISLASTCN) != 0);
                        }
                        break;
                }

                /*
                 * Stop and get a hold on the vnode if we've encountered
                 * something other than a directory.
                 */
                if (foundobj->v_type != VDIR) {
                        error = vcache_tryvget(foundobj);
                        if (error != 0) {
                                foundobj = NULL;
                                error = SET_ERROR(EOPNOTSUPP);
                        } else {
                                terminal = (foundobj->v_type != VLNK &&
                                    (cnp->cn_flags & ISLASTCN) != 0);
                        }
                        break;
                }

                /*
                 * Try to cross mountpoints, bearing in mind that they can
                 * be stacked.  If at any point we can't go further, stop
                 * and try to get a reference on the vnode.  If we are able
                 * to get a ref then lookup_crossmount() will take care of
                 * it, otherwise we'll fall through to lookup_once().
                 */
                if (foundobj->v_mountedhere != NULL) {
                        while (foundobj->v_mountedhere != NULL &&
                            (cnp->cn_flags & NOCROSSMOUNT) == 0 &&
                            cache_cross_mount(&foundobj, &plock)) {
                                KASSERT(foundobj != NULL);
                                KASSERT(foundobj->v_type == VDIR);
                        }
                        if (foundobj->v_mountedhere != NULL) {
                                error = vcache_tryvget(foundobj);
                                if (error != 0) {
                                        foundobj = NULL;
                                        error = SET_ERROR(EOPNOTSUPP);
                                }
                                break;
                        } else {
                                searchdir = NULL;
                        }
                }

                /*
                 * Time to stop if we found the last component & traversed
                 * all mounts.
                 */
                if ((cnp->cn_flags & ISLASTCN) != 0) {
                        error = vcache_tryvget(foundobj);
                        if (error != 0) {
                                foundobj = NULL;
                                error = SET_ERROR(EOPNOTSUPP);
                        } else {
                                terminal = (foundobj->v_type != VLNK);
                        }
                        break;
                }

                /*
                 * Otherwise, we're still in business.  Set the found VDIR
                 * vnode as the search dir for the next component and
                 * continue on to it.
                 */
                cnp->cn_nameptr = ndp->ni_next;
                searchdir = foundobj;
        }

        if (terminal) {
                /*
                 * If we exited the loop above having successfully located
                 * the last component with a zero error code, and it's not a
                 * symbolic link, then the parent directory is not needed.
                 * Release reference to the starting parent and make the
                 * terminal parent disappear into thin air.
                 */
                KASSERT(plock != NULL);
                rw_exit(plock);
                vrele(*searchdir_ret);
                *searchdir_ret = NULL;
        } else if (searchdir != *searchdir_ret) {
                /*
                 * Otherwise we need to return the parent.  If we ended up
                 * with a new search dir, ref it before dropping the
                 * namecache's lock.  The lock prevents both searchdir and
                 * foundobj from disappearing.  If we can't ref the new
                 * searchdir, we have a bit of a problem.  Roll back the
                 * fastforward to the beginning and let lookup_once() take
                 * care of it.
                 */
                if (searchdir == NULL) {
                        /*
                         * It's possible for searchdir to be NULL in the
                         * case of a root vnode being reclaimed while
                         * trying to cross a mount.
                         */
                        error2 = SET_ERROR(EOPNOTSUPP);
                } else {
                        error2 = vcache_tryvget(searchdir);
                }
                KASSERT(plock != NULL);
                rw_exit(plock);
                if (__predict_true(error2 == 0)) {
                        /* Returning new searchdir, and maybe new foundobj. */
                        vrele(*searchdir_ret);
                        *searchdir_ret = searchdir;
                } else {
                        /* Returning nothing. */
                        if (foundobj != NULL) {
                                vrele(foundobj);
                                foundobj = NULL;
                        }
                        cnp->cn_nameptr = oldnameptr;
                        ndp->ni_pathlen = oldpathlen;
                        error = lookup_parsepath(state, *searchdir_ret);
                        if (error == 0) {
                                error = SET_ERROR(EOPNOTSUPP);
                        }
                }
        } else if (plock != NULL) {
                /* Drop any namecache lock still held. */
                rw_exit(plock);
        }

        KASSERT(error == 0 ? foundobj != NULL : foundobj == NULL);
        *foundobj_ret = foundobj;
        return error;
}

//////////////////////////////

/*
 * Do a complete path search from a single root directory.
 * (This is called up to twice if TRYEMULROOT is in effect.)
 */
static int
namei_oneroot(struct namei_state *state,
    int neverfollow, int inhibitmagic, int isnfsd)
{
        struct nameidata *ndp = state->ndp;
        struct componentname *cnp = state->cnp;
        struct vnode *searchdir, *foundobj;
        bool searchdir_locked = false;
        int error;

        error = namei_start(state, isnfsd, &searchdir);
        if (error) {
                ndp->ni_dvp = NULL;
                ndp->ni_vp = NULL;
                return error;
        }
        KASSERT(searchdir->v_type == VDIR);

        /*
         * Setup: break out flag bits into variables.
         */
        state->docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
        if (cnp->cn_nameiop == DELETE)
                state->docache = 0;
        state->rdonly = cnp->cn_flags & RDONLY;

        /*
         * Keep going until we run out of path components.
         */
        cnp->cn_nameptr = ndp->ni_pnbuf;

        /* drop leading slashes (already used them to choose startdir) */
        while (cnp->cn_nameptr[0] == '/') {
                cnp->cn_nameptr++;
                ndp->ni_pathlen--;
        }
        /* was it just "/"? */
        if (cnp->cn_nameptr[0] == '\0') {
                foundobj = searchdir;
                searchdir = NULL;
                cnp->cn_flags |= ISLASTCN;

                /* bleh */
                goto skiploop;
        }

        for (;;) {
                KASSERT(searchdir != NULL);
                KASSERT(!searchdir_locked);

                /*
                 * Parse out the first path name component that we need to
                 * to consider.  While doing this, attempt to use the name
                 * cache to fast-forward through as many "easy" to find
                 * components of the path as possible.
                 */
                error = lookup_fastforward(state, &searchdir, &foundobj);

                /*
                 * If we didn't get a good answer from the namecache, then
                 * go directly to the file system.
                 */
                if (error == EOPNOTSUPP) {
                        error = lookup_once(state, searchdir, &searchdir,
                            &foundobj, &searchdir_locked);
                }

                /*
                 * If the vnode we found is mounted on, then cross the mount
                 * and get the root vnode in foundobj.  If this encounters
                 * an error, it will dispose of foundobj, but searchdir is
                 * untouched.
                 */
                if (error == 0 && foundobj != NULL &&
                    foundobj->v_type == VDIR &&
                    foundobj->v_mountedhere != NULL &&
                    (cnp->cn_flags & NOCROSSMOUNT) == 0) {
                        error = lookup_crossmount(state, &searchdir,
                            &foundobj, &searchdir_locked);
                }

                if (error) {
                        if (searchdir != NULL) {
                                if (searchdir_locked) {
                                        searchdir_locked = false;
                                        vput(searchdir);
                                } else {
                                        vrele(searchdir);
                                }
                        }
                        ndp->ni_dvp = NULL;
                        ndp->ni_vp = NULL;
                        /*
                         * Note that if we're doing TRYEMULROOT we can
                         * retry with the normal root. Where this is
                         * currently set matches previous practice,
                         * but the previous practice didn't make much
                         * sense and somebody should sit down and
                         * figure out which cases should cause retry
                         * and which shouldn't. XXX.
                         */
                        state->attempt_retry = 1;
                        return error;
                }

                if (foundobj == NULL) {
                        /*
                         * Success with no object returned means we're
                         * creating something and it isn't already
                         * there. Break out of the main loop now so
                         * the code below doesn't have to test for
                         * foundobj == NULL.
                         */
                        /* lookup_once can't have dropped the searchdir */
                        KASSERT(searchdir != NULL ||
                            (cnp->cn_flags & ISLASTCN) != 0);
                        break;
                }

                /*
                 * Check for symbolic link. If we've reached one,
                 * follow it, unless we aren't supposed to. Back up
                 * over any slashes that we skipped, as we will need
                 * them again.
                 */
                if (namei_atsymlink(state, foundobj)) {
                        /* Don't need searchdir locked any more. */
                        if (searchdir_locked) {
                                searchdir_locked = false;
                                VOP_UNLOCK(searchdir);
                        }
                        ndp->ni_pathlen += state->slashes;
                        ndp->ni_next -= state->slashes;
                        if (neverfollow) {
                                error = SET_ERROR(EINVAL);
                        } else if (searchdir == NULL) {
                                /*
                                 * dholland 20160410: lookup_once only
                                 * drops searchdir if it crossed a
                                 * mount point. Therefore, if we get
                                 * here it means we crossed a mount
                                 * point to a mounted filesystem whose
                                 * root vnode is a symlink. In theory
                                 * we could continue at this point by
                                 * using the pre-crossing searchdir
                                 * (e.g. just take out an extra
                                 * reference on it before calling
                                 * lookup_once so we still have it),
                                 * but this will make an ugly mess and
                                 * it should never happen in practice
                                 * as only badly broken filesystems
                                 * have non-directory root vnodes. (I
                                 * have seen this sort of thing with
                                 * NFS occasionally but even then it
                                 * means something's badly wrong.)
                                 */
                                error = SET_ERROR(ENOTDIR);
                        } else {
                                /*
                                 * dholland 20110410: if we're at a
                                 * union mount it might make sense to
                                 * use the top of the union stack here
                                 * rather than the layer we found the
                                 * symlink in. (FUTURE)
                                 */
                                error = namei_follow(state, inhibitmagic,
                                    searchdir, foundobj,
                                    &searchdir);
                        }
                        if (error) {
                                KASSERT(searchdir != foundobj);
                                if (searchdir != NULL) {
                                        vrele(searchdir);
                                }
                                vrele(foundobj);
                                ndp->ni_dvp = NULL;
                                ndp->ni_vp = NULL;
                                return error;
                        }
                        vrele(foundobj);
                        foundobj = NULL;

                        /*
                         * If we followed a symlink to `/' and there
                         * are no more components after the symlink,
                         * we're done with the loop and what we found
                         * is the searchdir.
                         */
                        if (cnp->cn_nameptr[0] == '\0') {
                                KASSERT(searchdir != NULL);
                                foundobj = searchdir;
                                searchdir = NULL;
                                cnp->cn_flags |= ISLASTCN;
                                break;
                        }

                        continue;
                }

                /*
                 * Not a symbolic link.
                 *
                 * Check for directory, if the component was
                 * followed by a series of slashes.
                 */
                if ((foundobj->v_type != VDIR) &&
                    (cnp->cn_flags & REQUIREDIR)) {
                        KASSERT(foundobj != searchdir);
                        if (searchdir) {
                                if (searchdir_locked) {
                                        searchdir_locked = false;
                                        vput(searchdir);
                                } else {
                                        vrele(searchdir);
                                }
                        } else {
                                KASSERT(!searchdir_locked);
                        }
                        vrele(foundobj);
                        ndp->ni_dvp = NULL;
                        ndp->ni_vp = NULL;
                        state->attempt_retry = 1;
                        return SET_ERROR(ENOTDIR);
                }

                /*
                 * Stop if we've reached the last component.
                 */
                if (cnp->cn_flags & ISLASTCN) {
                        break;
                }

                /*
                 * Continue with the next component.
                 */
                cnp->cn_nameptr = ndp->ni_next;
                if (searchdir != NULL) {
                        if (searchdir_locked) {
                                searchdir_locked = false;
                                vput(searchdir);
                        } else {
                                vrele(searchdir);
                        }
                }
                searchdir = foundobj;
                foundobj = NULL;
        }

        KASSERT((cnp->cn_flags & LOCKPARENT) == 0 || searchdir == NULL ||
            VOP_ISLOCKED(searchdir) == LK_EXCLUSIVE);

skiploop:
        if (foundobj != NULL) {
                if (foundobj == ndp->ni_erootdir) {
                        /*
                         * We are about to return the emulation root.
                         * This isn't a good idea because code might
                         * repeatedly lookup ".." until the file
                         * matches that returned for "/" and loop
                         * forever.  So convert it to the real root.
                         */
                        if (searchdir != NULL) {
                                if (searchdir_locked) {
                                        vput(searchdir);
                                        searchdir_locked = false;
                                } else {
                                        vrele(searchdir);
                                }
                                searchdir = NULL;
                        }
                        vrele(foundobj);
                        foundobj = ndp->ni_rootdir;
                        vref(foundobj);
                }

                /*
                 * If the caller requested the parent node (i.e. it's
                 * a CREATE, DELETE, or RENAME), and we don't have one
                 * (because this is the root directory, or we crossed
                 * a mount point), then we must fail.
                 *
                 * 20210604 dholland when NONEXCLHACK is set (open
                 * with O_CREAT but not O_EXCL) skip this logic. Since
                 * we have a foundobj, open will not be creating, so
                 * it doesn't actually need or use the searchdir, so
                 * it's ok to return it even if it's on a different
                 * volume, and it's also ok to return NULL; by setting
                 * NONEXCLHACK the open code promises to cope with
                 * those cases correctly. (That is, it should do what
                 * it would do anyway, that is, just release the
                 * searchdir, except not crash if it's null.) This is
                 * needed because otherwise opening mountpoints with
                 * O_CREAT but not O_EXCL fails... which is a silly
                 * thing to do but ought to work. (This whole issue
                 * came to light because 3rd party code wanted to open
                 * certain procfs nodes with O_CREAT for some 3rd
                 * party reason, and it failed.)
                 *
                 * Note that NONEXCLHACK is properly a different
                 * nameiop (it is partway between LOOKUP and CREATE)
                 * but it was stuffed in as a flag instead to make the
                 * resulting patch less invasive for pullup. Blah.
                 */
                if (cnp->cn_nameiop != LOOKUP &&
                    (searchdir == NULL ||
                        searchdir->v_mount != foundobj->v_mount) &&
                    (cnp->cn_flags & NONEXCLHACK) == 0) {
                        if (searchdir) {
                                if (searchdir_locked) {
                                        vput(searchdir);
                                        searchdir_locked = false;
                                } else {
                                        vrele(searchdir);
                                }
                                searchdir = NULL;
                        }
                        vrele(foundobj);
                        foundobj = NULL;
                        ndp->ni_dvp = NULL;
                        ndp->ni_vp = NULL;
                        state->attempt_retry = 1;

                        switch (cnp->cn_nameiop) {
                        case CREATE:
                                return SET_ERROR(EEXIST);
                        case DELETE:
                        case RENAME:
                                return SET_ERROR(EBUSY);
                        default:
                                break;
                        }
                        panic("Invalid nameiop\n");
                }

                /*
                 * Disallow directory write attempts on read-only lookups.
                 * Prefers EEXIST over EROFS for the CREATE case.
                 */
                if (state->rdonly &&
                    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
                        if (searchdir) {
                                if (searchdir_locked) {
                                        vput(searchdir);
                                        searchdir_locked = false;
                                } else {
                                        vrele(searchdir);
                                }
                                searchdir = NULL;
                        }
                        vrele(foundobj);
                        foundobj = NULL;
                        ndp->ni_dvp = NULL;
                        ndp->ni_vp = NULL;
                        state->attempt_retry = 1;
                        return SET_ERROR(EROFS);
                }

                /* Lock the leaf node if requested. */
                if ((cnp->cn_flags & (LOCKLEAF | LOCKPARENT)) == LOCKPARENT &&
                    searchdir == foundobj) {
                        /*
                         * Note: if LOCKPARENT but not LOCKLEAF is
                         * set, and searchdir == foundobj, this code
                         * necessarily unlocks the parent as well as
                         * the leaf. That is, just because you specify
                         * LOCKPARENT doesn't mean you necessarily get
                         * a locked parent vnode. The code in
                         * vfs_syscalls.c, and possibly elsewhere,
                         * that uses this combination "knows" this, so
                         * it can't be safely changed. Feh. XXX
                         */
                        KASSERT(searchdir_locked);
                        VOP_UNLOCK(searchdir);
                        searchdir_locked = false;
                } else if ((cnp->cn_flags & LOCKLEAF) != 0 &&
                    (searchdir != foundobj ||
                        (cnp->cn_flags & LOCKPARENT) == 0)) {
                        const int lktype = (cnp->cn_flags & LOCKSHARED) != 0 ?
                            LK_SHARED : LK_EXCLUSIVE;
                        vn_lock(foundobj, lktype | LK_RETRY);
                }
        }

        /*
         * Done.
         */

        /*
         * If LOCKPARENT is not set, the parent directory isn't returned.
         */
        if ((cnp->cn_flags & LOCKPARENT) == 0 && searchdir != NULL) {
                vrele(searchdir);
                searchdir = NULL;
        }

        ndp->ni_dvp = searchdir;
        ndp->ni_vp = foundobj;
        return 0;
}

/*
 * Do namei; wrapper layer that handles TRYEMULROOT.
 */
static int
namei_tryemulroot(struct namei_state *state,
    int neverfollow, int inhibitmagic, int isnfsd)
{
        int error;

        struct nameidata *ndp = state->ndp;
        struct componentname *cnp = state->cnp;
        const char *savepath = NULL;

        KASSERT(cnp == &ndp->ni_cnd);

        if (cnp->cn_flags & TRYEMULROOT) {
                savepath = pathbuf_stringcopy_get(ndp->ni_pathbuf);
        }

emul_retry:
        state->attempt_retry = 0;

        error = namei_oneroot(state, neverfollow, inhibitmagic, isnfsd);
        if (error) {
                /*
                 * Once namei has started up, the existence of ni_erootdir
                 * tells us whether we're working from an emulation root.
                 * The TRYEMULROOT flag isn't necessarily authoritative.
                 */
                if (ndp->ni_erootdir != NULL && state->attempt_retry) {
                        /* Retry the whole thing using the normal root */
                        cnp->cn_flags &= ~TRYEMULROOT;
                        state->attempt_retry = 0;

                        /* kinda gross */
                        strcpy(ndp->ni_pathbuf->pb_path, savepath);
                        pathbuf_stringcopy_put(ndp->ni_pathbuf, savepath);
                        savepath = NULL;

                        goto emul_retry;
                }
        }
        if (savepath != NULL) {
                pathbuf_stringcopy_put(ndp->ni_pathbuf, savepath);
        }
        return error;
}

/*
 * External interface.
 */
int
namei(struct nameidata *ndp)
{
        struct namei_state state;
        int error;

        namei_init(&state, ndp);
        error = namei_tryemulroot(&state,
            0/*!neverfollow*/, 0/*!inhibitmagic*/, 0/*isnfsd*/);
        namei_cleanup(&state);

        if (error) {
                /* make sure no stray refs leak out */
                KASSERT(ndp->ni_dvp == NULL);
                KASSERT(ndp->ni_vp == NULL);
        }

        return error;
}

////////////////////////////////////////////////////////////

/*
 * External interface used by nfsd. This is basically different from
 * namei only in that it has the ability to pass in the "current
 * directory", and uses an extra flag "neverfollow" for which there's
 * no physical flag defined in namei.h. (There used to be a cut&paste
 * copy of about half of namei in nfsd to allow these minor
 * adjustments to exist.)
 *
 * XXX: the namei interface should be adjusted so nfsd can just use
 * ordinary namei().
 */
int
lookup_for_nfsd(struct nameidata *ndp, struct vnode *forcecwd, int neverfollow)
{
        struct namei_state state;
        int error;

        KASSERT(ndp->ni_atdir == NULL);
        ndp->ni_atdir = forcecwd;

        namei_init(&state, ndp);
        error = namei_tryemulroot(&state,
            neverfollow, 1/*inhibitmagic*/, 1/*isnfsd*/);
        namei_cleanup(&state);

        if (error) {
                /* make sure no stray refs leak out */
                KASSERT(ndp->ni_dvp == NULL);
                KASSERT(ndp->ni_vp == NULL);
        }

        return error;
}

/*
 * A second external interface used by nfsd. This turns out to be a
 * single lookup used by the WebNFS code (ha!) to get "index.html" or
 * equivalent when asked for a directory. It should eventually evolve
 * into some kind of namei_once() call; for the time being it's kind
 * of a mess. XXX.
 *
 * dholland 20110109: I don't think it works, and I don't think it
 * worked before I started hacking and slashing either, and I doubt
 * anyone will ever notice.
 */

/*
 * Internals. This calls lookup_once() after setting up the assorted
 * pieces of state the way they ought to be.
 */
static int
do_lookup_for_nfsd_index(struct namei_state *state)
{
        int error;

        struct componentname *cnp = state->cnp;
        struct nameidata *ndp = state->ndp;
        struct vnode *startdir;
        struct vnode *foundobj;
        bool startdir_locked;
        const char *cp;                 /* pointer into pathname argument */

        KASSERT(cnp == &ndp->ni_cnd);

        startdir = state->ndp->ni_atdir;

        cnp->cn_nameptr = ndp->ni_pnbuf;
        state->docache = 1;
        state->rdonly = cnp->cn_flags & RDONLY;
        ndp->ni_dvp = NULL;

        error = VOP_PARSEPATH(startdir, cnp->cn_nameptr, &cnp->cn_namelen);
        if (error) {
                return error;
        }

        cp = cnp->cn_nameptr + cnp->cn_namelen;
        KASSERT(cnp->cn_namelen <= KERNEL_NAME_MAX);
        ndp->ni_pathlen -= cnp->cn_namelen;
        ndp->ni_next = cp;
        state->slashes = 0;
        cnp->cn_flags &= ~REQUIREDIR;
        cnp->cn_flags |= MAKEENTRY|ISLASTCN;

        if (cnp->cn_namelen == 2 &&
            cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
                cnp->cn_flags |= ISDOTDOT;
        else
                cnp->cn_flags &= ~ISDOTDOT;

        /*
         * Because lookup_once can change the startdir, we need our
         * own reference to it to avoid consuming the caller's.
         */
        vref(startdir);
        error = lookup_once(state, startdir, &startdir, &foundobj,
            &startdir_locked);

        KASSERT((cnp->cn_flags & LOCKPARENT) == 0);
        if (startdir_locked) {
                VOP_UNLOCK(startdir);
                startdir_locked = false;
        }

        /*
         * If the vnode we found is mounted on, then cross the mount and get
         * the root vnode in foundobj.  If this encounters an error, it will
         * dispose of foundobj, but searchdir is untouched.
         */
        if (error == 0 && foundobj != NULL &&
            foundobj->v_type == VDIR &&
            foundobj->v_mountedhere != NULL &&
            (cnp->cn_flags & NOCROSSMOUNT) == 0) {
                error = lookup_crossmount(state, &startdir, &foundobj,
                    &startdir_locked);
        }

        /* Now toss startdir and see if we have an error. */
        if (startdir != NULL)
                vrele(startdir);
        if (error)
                foundobj = NULL;
        else if (foundobj != NULL && (cnp->cn_flags & LOCKLEAF) != 0)
                vn_lock(foundobj, LK_EXCLUSIVE | LK_RETRY);

        ndp->ni_vp = foundobj;
        return error;
}

/*
 * External interface. The partitioning between this function and the
 * above isn't very clear - the above function exists mostly so code
 * that uses "state->" can be shuffled around without having to change
 * it to "state.".
 */
int
lookup_for_nfsd_index(struct nameidata *ndp, struct vnode *startdir)
{
        struct namei_state state;
        int error;

        KASSERT(ndp->ni_atdir == NULL);
        ndp->ni_atdir = startdir;

        /*
         * Note: the name sent in here (is not|should not be) allowed
         * to contain a slash.
         */
        if (strlen(ndp->ni_pathbuf->pb_path) > KERNEL_NAME_MAX) {
                return SET_ERROR(ENAMETOOLONG);
        }
        if (strchr(ndp->ni_pathbuf->pb_path, '/')) {
                return SET_ERROR(EINVAL);
        }

        ndp->ni_pathlen = strlen(ndp->ni_pathbuf->pb_path) + 1;
        ndp->ni_pnbuf = NULL;
        ndp->ni_cnd.cn_nameptr = NULL;

        namei_init(&state, ndp);
        error = do_lookup_for_nfsd_index(&state);
        namei_cleanup(&state);

        return error;
}

////////////////////////////////////////////////////////////

/*
 * Reacquire a path name component.
 * dvp is locked on entry and exit.
 * *vpp is locked on exit unless it's NULL.
 */
int
relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
    int dummy)
{
        int rdonly;                     /* lookup read-only flag bit */
        int error = 0;
#ifdef DEBUG
        size_t newlen;                  /* DEBUG: check name len */
        const char *cp;                 /* DEBUG: check name ptr */
#endif /* DEBUG */

        (void)dummy;

        /*
         * Setup: break out flag bits into variables.
         */
        rdonly = cnp->cn_flags & RDONLY;

        /*
         * Search a new directory.
         *
         * The cn_hash value is for use by vfs_cache.
         * The last component of the filename is left accessible via
         * cnp->cn_nameptr for callers that need the name. Callers needing
         * the name set the SAVENAME flag. When done, they assume
         * responsibility for freeing the pathname buffer.
         */
#ifdef DEBUG
#if 0
        cp = NULL;
        newhash = namei_hash(cnp->cn_nameptr, &cp);
        if ((uint32_t)newhash != (uint32_t)cnp->cn_hash)
                panic("relookup: bad hash");
#endif
        error = VOP_PARSEPATH(dvp, cnp->cn_nameptr, &newlen);
        if (error) {
                panic("relookup: parsepath failed with error %d", error);
        }
        if (cnp->cn_namelen != newlen)
                panic("relookup: bad len");
        cp = cnp->cn_nameptr + cnp->cn_namelen;
        while (*cp == '/')
                cp++;
        if (*cp != 0)
                panic("relookup: not last component");
#endif /* DEBUG */

        /*
         * Check for degenerate name (e.g. / or "")
         * which is a way of talking about a directory,
         * e.g. like "/." or ".".
         */
        if (cnp->cn_nameptr[0] == '\0')
                panic("relookup: null name");

        if (cnp->cn_flags & ISDOTDOT)
                panic("relookup: lookup on dot-dot");

        /*
         * We now have a segment name to search for, and a directory to search.
         */
        *vpp = NULL;
        error = VOP_LOOKUP(dvp, vpp, cnp);
        if ((error) != 0) {
                KASSERTMSG((*vpp == NULL),
                    "leaf `%s' should be empty but is %p",
                    cnp->cn_nameptr, *vpp);
                if (error != EJUSTRETURN)
                        goto bad;
        }

        /*
         * Check for symbolic link
         */
        KASSERTMSG((*vpp == NULL || (*vpp)->v_type != VLNK ||
                (cnp->cn_flags & FOLLOW) == 0),
            "relookup: symlink found");

        /*
         * Check for read-only lookups.
         */
        if (rdonly && cnp->cn_nameiop != LOOKUP) {
                error = SET_ERROR(EROFS);
                if (*vpp) {
                        vrele(*vpp);
                }
                goto bad;
        }
        /*
         * Lock result.
         */
        if (*vpp && *vpp != dvp) {
                error = vn_lock(*vpp, LK_EXCLUSIVE);
                if (error != 0) {
                        vrele(*vpp);
                        goto bad;
                }
        }
        return 0;

bad:
        *vpp = NULL;
        return error;
}

/*
 * namei_simple - simple forms of namei.
 *
 * These are wrappers to allow the simple case callers of namei to be
 * left alone while everything else changes under them.
 */

/* Flags */
struct namei_simple_flags_type {
        int dummy;
};
static const struct namei_simple_flags_type ns_nn, ns_nt, ns_fn, ns_ft;
const namei_simple_flags_t NSM_NOFOLLOW_NOEMULROOT = &ns_nn;
const namei_simple_flags_t NSM_NOFOLLOW_TRYEMULROOT = &ns_nt;
const namei_simple_flags_t NSM_FOLLOW_NOEMULROOT = &ns_fn;
const namei_simple_flags_t NSM_FOLLOW_TRYEMULROOT = &ns_ft;

static int
namei_simple_convert_flags(namei_simple_flags_t sflags)
{

        if (sflags == NSM_NOFOLLOW_NOEMULROOT)
                return NOFOLLOW | 0;
        if (sflags == NSM_NOFOLLOW_TRYEMULROOT)
                return NOFOLLOW | TRYEMULROOT;
        if (sflags == NSM_FOLLOW_NOEMULROOT)
                return FOLLOW | 0;
        if (sflags == NSM_FOLLOW_TRYEMULROOT)
                return FOLLOW | TRYEMULROOT;
        panic("namei_simple_convert_flags: bogus sflags\n");
        return 0;
}

int
namei_simple_kernel(const char *path, namei_simple_flags_t sflags,
    struct vnode **vp_ret)
{

        return nameiat_simple_kernel(NULL, path, sflags, vp_ret);
}

int
nameiat_simple(struct vnode *dvp, struct pathbuf *pb,
    namei_simple_flags_t sflags, struct vnode **vp_ret)
{
        struct nameidata nd;
        int error;

        NDINIT(&nd, LOOKUP, namei_simple_convert_flags(sflags), pb);

        if (dvp != NULL)
                NDAT(&nd, dvp);

        error = namei(&nd);
        if (error != 0)
                return error;

        *vp_ret = nd.ni_vp;
        return 0;
}

int
nameiat_simple_kernel(struct vnode *dvp, const char *path,
    namei_simple_flags_t sflags, struct vnode **vp_ret)
{
        struct pathbuf *pb;
        int error;

        pb = pathbuf_create(path);
        if (pb == NULL)
                return SET_ERROR(ENOMEM);

        error = nameiat_simple(dvp, pb, sflags, vp_ret);

        pathbuf_destroy(pb);
        return error;
}

int
namei_simple_user(const char *path, namei_simple_flags_t sflags,
    struct vnode **vp_ret)
{

        return nameiat_simple_user(NULL, path, sflags, vp_ret);
}

int
nameiat_simple_user(struct vnode *dvp, const char *path,
    namei_simple_flags_t sflags, struct vnode **vp_ret)
{
        struct pathbuf *pb;
        int error;

        error = pathbuf_copyin(path, &pb);
        if (error)
                return error;

        error = nameiat_simple(dvp, pb, sflags, vp_ret);

        pathbuf_destroy(pb);
        return error;
}