xnu-517.tar.gz

[apple/xnu.git] / bsd / hfs / hfs_lookup.c

/*
 * Copyright (c) 1999-2003 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *        notice, this list of conditions and the following disclaimer in the
 *        documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *        must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *        may be used to endorse or promote products derived from this software
 *        without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.      IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)hfs_lookup.c        1.0
 *      derived from @(#)ufs_lookup.c   8.15 (Berkeley) 6/16/95
 *
 *      (c) 1998-1999   Apple Computer, Inc.     All Rights Reserved
 *      (c) 1990, 1992  NeXT Computer, Inc.     All Rights Reserved
 *      
 *
 *      hfs_lookup.c -- code to handle directory traversal on HFS/HFS+ volume
 */
#define LEGACY_FORK_NAMES       0

#include <sys/param.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/paths.h>

#include "hfs.h"
#include "hfs_catalog.h"
#include "hfs_cnode.h"


static int forkcomponent(struct componentname *cnp, int *rsrcfork);

#define _PATH_DATAFORKSPEC      "/..namedfork/data"

#ifdef LEGACY_FORK_NAMES
#define LEGACY_RSRCFORKSPEC     "/rsrc"
#endif

/*      
 * FROM FREEBSD 3.1
 * Convert a component of a pathname into a pointer to a locked cnode.
 * This is a very central and rather complicated routine.
 * If the file system is not maintained in a strict tree hierarchy,
 * this can result in a deadlock situation (see comments in code below).
 *
 * The cnp->cn_nameiop 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.
 * Notice that these are the only operations that can affect the directory of the target.
 *
 * If flag has LOCKPARENT or'ed into it and the target of the pathname
 * exists, lookup returns both the target and its parent directory locked.
 * When creating or renaming and LOCKPARENT is specified, the target may
 * not be ".".  When deleting and LOCKPARENT is specified, the target may
 * be "."., but the caller must check to ensure it does an vrele and vput
 * instead of two vputs.
 *
 * LOCKPARENT and WANTPARENT actually refer to the parent of the last item,
 * so if ISLASTCN is not set, they should be ignored. Also they are mutually exclusive, or
 * WANTPARENT really implies DONTLOCKPARENT. Either of them set means that the calling
 * routine wants to access the parent of the target, locked or unlocked.
 *
 * Keeping the parent locked as long as possible protects from other processes
 * looking up the same item, so it has to be locked until the cnode is totally finished
 *
 * This routine is actually used as VOP_CACHEDLOOKUP method, and the
 * filesystem employs the generic hfs_cache_lookup() as VOP_LOOKUP
 * method.
 *
 * hfs_cache_lookup() performs the following for us:
 *      check that it is a directory
 *      check accessibility of directory
 *      check for modification attempts on read-only mounts
 *      if name found in cache
 *              if at end of path and deleting or creating
 *              drop it
 *               else
 *              return name.
 *      return VOP_CACHEDLOOKUP()
 *
 * Overall outline of hfs_lookup:
 *
 *      handle simple cases of . and ..
 *      search for name in directory, to found or notfound
 * notfound:
 *      if creating, return locked directory, leaving info on available slots
 *      else return error
 * found:
 *      if at end of path and deleting, return information to allow delete
 *      if at end of path and rewriting (RENAME and LOCKPARENT), lock target
 *        cnode and return info to allow rewrite
 *      if not at end, add name to cache; if at end and neither creating
 *        nor deleting, add name to cache
 */

/*      
 *      Lookup *nm in directory *pvp, return it in *a_vpp.
 *      **a_vpp is held on exit.
 *      We create a cnode for the file, but we do NOT open the file here.

#% lookup       dvp L ? ?
#% lookup       vpp - L -

        IN struct vnode *dvp - Parent node of file;
        INOUT struct vnode **vpp - node of target file, its a new node if
                the target vnode did not exist;
        IN struct componentname *cnp - Name of file;

 *      When should we lock parent_hp in here ??
 */

__private_extern__
int
hfs_lookup(ap)
        struct vop_cachedlookup_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
        } */ *ap;
{
        struct vnode *dvp;      /* vnode for directory being searched */
        struct cnode *dcp;      /* cnode for directory being searched */
        struct vnode *tvp;      /* target vnode */
        struct hfsmount *hfsmp;
        struct componentname *cnp;      
        struct ucred *cred;
        struct proc *p;
        int wantrsrc = 0;
        int forknamelen = 0;
        int flags;
        int wantparent;
        int nameiop;
        int retval = 0;
        int isDot;
        struct cat_desc desc = {0};
        struct cat_desc cndesc;
        struct cat_attr attr;
        struct cat_fork fork;
        struct vnode **vpp;

        vpp = ap->a_vpp;
        cnp = ap->a_cnp;
        dvp = ap->a_dvp;
        dcp = VTOC(dvp);
        hfsmp = VTOHFS(dvp);
        *vpp = NULL;
        isDot = FALSE;
        tvp = NULL;
        nameiop = cnp->cn_nameiop;
        cred = cnp->cn_cred;
        p = cnp->cn_proc;
        flags = cnp->cn_flags;
        wantparent = flags & (LOCKPARENT|WANTPARENT);

        /*
         * First check to see if it is a . or .., else look it up.
         */
        if (flags & ISDOTDOT) {         /* Wanting the parent */
                goto found;     /* .. is always defined */
        } else if ((cnp->cn_nameptr[0] == '.') && (cnp->cn_namelen == 1)) {
                isDot = TRUE;
                goto found;     /* We always know who we are */
        } else {
                /* Check fork suffix to see if we want the resource fork */
                forknamelen = forkcomponent(cnp, &wantrsrc);

                /* No need to go to catalog if there are no children */
                if (dcp->c_entries == 0)
                        goto notfound;

                bzero(&cndesc, sizeof(cndesc));
                cndesc.cd_nameptr = cnp->cn_nameptr;
                cndesc.cd_namelen = cnp->cn_namelen;
                cndesc.cd_parentcnid = dcp->c_cnid;
                cndesc.cd_hint = dcp->c_childhint;

                /* Lock catalog b-tree */
                retval = hfs_metafilelocking(hfsmp, kHFSCatalogFileID, LK_SHARED, p);
                if (retval)
                           goto exit;
                retval = cat_lookup(hfsmp, &cndesc, wantrsrc, &desc, &attr, &fork);
                
                if (retval == 0 && S_ISREG(attr.ca_mode) && attr.ca_blocks < fork.cf_blocks)
                        panic("hfs_lookup: bad ca_blocks (too small)");
        
                /* Unlock catalog b-tree */
                (void) hfs_metafilelocking(hfsmp, kHFSCatalogFileID, LK_RELEASE, p);
                if (retval == 0) {
                        dcp->c_childhint = desc.cd_hint;
                        goto found;
                }
notfound:
                /*
                 * This is a non-existing entry
                 *
                 * If creating, and at end of pathname and current
                 * directory has not been removed, then can consider
                 * allowing file to be created.
                 */
                if ((nameiop == CREATE || nameiop == RENAME ||
                    (nameiop == DELETE &&
                    (ap->a_cnp->cn_flags & DOWHITEOUT) &&
                    (ap->a_cnp->cn_flags & ISWHITEOUT))) &&
                    (flags & ISLASTCN)) {
                        /*
                         * Access for write is interpreted as allowing
                         * creation of files in the directory.
                         */
                        retval = VOP_ACCESS(dvp, VWRITE, cred, cnp->cn_proc);
                        if (retval) {
                                goto exit;
                        }
                
                        cnp->cn_flags |= SAVENAME;
                        if (!(flags & LOCKPARENT))
                                VOP_UNLOCK(dvp, 0, p);
                        retval = EJUSTRETURN;
                        goto exit;
                }

                /*
                 * Insert name into cache (as non-existent) if appropriate.
                 *
                 * Only done for case-sensitive HFS+ volumes.
                 */
                if ((hfsmp->hfs_flags & HFS_CASE_SENSITIVE) &&
                    (cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
                        cache_enter(dvp, *vpp, cnp);
                retval = ENOENT;
                goto exit;
        }

found:
        /*
         * Process any fork specifiers
         */
        if (forknamelen && S_ISREG(attr.ca_mode)) {
                /* fork names are only for lookups */
                if ((nameiop != LOOKUP) && (nameiop != CREATE)) {
                        retval = EPERM;  
                        goto exit;
                }
                cnp->cn_consume = forknamelen;
                flags |= ISLASTCN;
        } else {
                wantrsrc = 0;
                forknamelen = 0;
        }

        /*
         * If deleting, and at end of pathname, return
         * parameters which can be used to remove file.
         */
        if (nameiop == DELETE && (flags & ISLASTCN)) {
                /*
                * Write access to directory required to delete files.
                */
                if ((retval = VOP_ACCESS(dvp, VWRITE, cred, cnp->cn_proc)))
                        goto exit;
                
                if (isDot) {    /* Want to return ourselves */
                        VREF(dvp);
                        *vpp = dvp;
                        goto exit;
                } else if (flags & ISDOTDOT) {
                        retval = hfs_getcnode(hfsmp, dcp->c_parentcnid,
                                NULL, 0, NULL, NULL, &tvp);
                        if (retval)
                                goto exit;
                } else {
                        retval = hfs_getcnode(hfsmp, attr.ca_fileid,
                                &desc, wantrsrc, &attr, &fork, &tvp);
                        if (retval)
                                goto exit;
                }

                /*
                 * If directory is "sticky", then user must own
                 * the directory, or the file in it, else she
                 * may not delete it (unless she's root). This
                 * implements append-only directories.
                 */
                if ((dcp->c_mode & S_ISTXT) &&
                        (cred->cr_uid != 0) &&
                        (cred->cr_uid != dcp->c_uid) &&
                        (tvp->v_type != VLNK) &&
                        (hfs_owner_rights(hfsmp, VTOC(tvp)->c_uid, cred, p, false))) {
                        vput(tvp);
                        retval = EPERM;
                        goto exit;
                }

                /*
                 * If this is a link node then we need to save the name
                 * (of the link) so we can delete it from the catalog b-tree.
                 * In this case, hfs_remove will then free the component name.
                 *
                 * DJB - IS THIS STILL NEEDED????
                 */
                if (tvp && (VTOC(tvp)->c_flag & C_HARDLINK))
                        cnp->cn_flags |= SAVENAME;
  
                if (!(flags & LOCKPARENT))
                        VOP_UNLOCK(dvp, 0, p);
                *vpp = tvp;
                goto exit;
         }

        /*
         * If renaming, return the cnode and save the current name.
         */
        if (nameiop == RENAME && wantparent && (flags & ISLASTCN)) {
                if ((retval = VOP_ACCESS(dvp, VWRITE, cred, cnp->cn_proc)) != 0)
                        goto exit;
                /*
                 * Careful about locking second cnode.
                 */
                if (isDot) {
                        retval = EISDIR;
                        goto exit;
                } else if (flags & ISDOTDOT) {
                        retval = hfs_getcnode(hfsmp, dcp->c_parentcnid,
                                NULL, 0, NULL, NULL, &tvp);
                        if (retval)
                                goto exit;
                } else {
                        retval = hfs_getcnode(hfsmp, attr.ca_fileid,
                                &desc, wantrsrc, &attr, &fork, &tvp);
                        if (retval)
                                goto exit;
                }
                cnp->cn_flags |= SAVENAME;
                if (!(flags & LOCKPARENT))
                        VOP_UNLOCK(dvp, 0, p);
                *vpp = tvp;
                goto exit;
         }

        /*
         * We must get the target cnode before unlocking
         * the directory to insure that the cnode will not be removed
         * before we get it.  We prevent deadlock by always fetching
         * cnodes from the root, moving down the directory tree. Thus
         * when following backward pointers ".." we must unlock the
         * parent directory before getting the requested directory.
         * There is a potential race condition here if both the current
         * and parent directories are removed before the VFS_VGET for the
         * cnode associated with ".." returns.  We hope that this occurs
         * infrequently since we cannot avoid this race condition without
         * implementing a sophisticated deadlock detection algorithm.
         */
        if (flags & ISDOTDOT) {
                VOP_UNLOCK(dvp, 0, p);  /* race to get the cnode */
                retval = hfs_getcnode(hfsmp, dcp->c_parentcnid,
                        NULL, 0, NULL, NULL, &tvp);
                if (retval) {
                        vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, p);
                        goto exit;
                }
                if ((flags & LOCKPARENT) && (flags & ISLASTCN) && (dvp != tvp) && 
                    (retval = vn_lock(dvp, LK_EXCLUSIVE, p))) {
                        vput(tvp);
                        goto exit;
                }
                *vpp = tvp;
        } else if (isDot) {
                VREF(dvp);      /* we want ourself, ie "." */
                *vpp = dvp;
        } else {
                int type = (attr.ca_mode & S_IFMT);

                if (!(flags & ISLASTCN) && type != S_IFDIR && type != S_IFLNK) {
                        retval = ENOTDIR;
                        goto exit;
                }

                retval = hfs_getcnode(hfsmp, attr.ca_fileid,
                        &desc, wantrsrc, &attr, &fork, &tvp);
                if (retval)
                        goto exit;

                if (!(flags & LOCKPARENT) || !(flags & ISLASTCN))
                        VOP_UNLOCK(dvp, 0, p);
                *vpp = tvp;
        }

        /*
         * Insert name in cache if appropriate.
         *  - "." and ".." are not cached.
         *  - Resource fork names are not cached.
         *  - Names with composed chars are not cached.
         */
        if ((cnp->cn_flags & MAKEENTRY)
            && !isDot
            && !(flags & ISDOTDOT)
            && !wantrsrc
            && (cnp->cn_namelen == VTOC(*vpp)->c_desc.cd_namelen)) {
                cache_enter(dvp, *vpp, cnp);
        }


        //
        // have to patch up the resource fork name because
        // it won't happen properly in the layers above us.
        //
        if (wantrsrc) {
            if (VTOC(*vpp)->c_vp == NULL) {
                if (VNAME(*vpp) == NULL) {
                    VNAME(*vpp) = add_name(cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, 0);
                }
                if (VPARENT(*vpp) == NULL) {
                    vget(dvp, 0, p);
                    VPARENT(*vpp) = dvp;
                }
            } else {
                if (VNAME(*vpp) == NULL) {
                    // the +1/-2 thing is to skip the leading "/" on the rsrc fork spec
                    // and to not count the trailing null byte at the end of the string.
                    VNAME(*vpp) = add_name(_PATH_RSRCFORKSPEC+1, sizeof(_PATH_RSRCFORKSPEC)-2, 0, 0);
                }
                if (VPARENT(*vpp) == NULL && *vpp != VTOC(*vpp)->c_vp) {
                    VPARENT(*vpp) = VTOC(*vpp)->c_vp;
                    VTOC(*vpp)->c_flag |= C_VPREFHELD;
                    vget(VTOC(*vpp)->c_vp, 0, p);
                }
            }
        }

exit:
        cat_releasedesc(&desc);
        return (retval);
}



/*
 * Based on vn_cache_lookup (which is vfs_cache_lookup in FreeBSD 3.1)
 *
 * Name caching works as follows:
 *
 * Names found by directory scans are retained in a cache
 * for future reference.  It is managed LRU, so frequently
 * used names will hang around.  Cache is indexed by hash value
 * obtained from (vp, name) where vp refers to the directory
 * containing name.
 *
 * If it is a "negative" entry, (i.e. for a name that is known NOT to
 * exist) the vnode pointer will be NULL.
 *
 * Upon reaching the last segment of a path, if the reference
 * is for DELETE, or NOCACHE is set (rewrite), and the
 * name is located in the cache, it will be dropped.
 *
 */

#define S_IXALL 0000111

__private_extern__
int
hfs_cache_lookup(ap)
        struct vop_lookup_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
        } */ *ap;
{
        struct vnode *dvp;
        struct vnode *vp;
        struct cnode *cp;
        struct cnode *dcp;
        int lockparent; 
        int error;
        struct vnode **vpp = ap->a_vpp;
        struct componentname *cnp = ap->a_cnp;
        int flags = cnp->cn_flags;
        struct proc *p = cnp->cn_proc;
        u_long vpid;    /* capability number of vnode */

        dvp = ap->a_dvp;
        lockparent = flags & LOCKPARENT;

        /*
         * Check accessiblity of directory.
         */
        if (dvp->v_type != VDIR)
                return (ENOTDIR);
        if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
            (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
                error = EROFS;
                goto err_exit;
        }
        dcp = VTOC(dvp);

        if (((dcp->c_mode & S_IXALL) != S_IXALL) && (cnp->cn_cred->cr_uid != 0)) {
                if ((error = VOP_ACCESS(dvp, VEXEC, cnp->cn_cred, p))) {
                        goto err_exit;
                }
        }
        /*
         * Lookup an entry in the cache
         * If the lookup succeeds, the vnode is returned in *vpp, and a status of -1 is
         * returned. If the lookup determines that the name does not exist
         * (negative cacheing), a status of ENOENT is returned. If the lookup
         * fails, a status of zero is returned.
         */
        error = cache_lookup(dvp, vpp, cnp);
        if (error != -1) {
                if (error == 0)  {              /* Unsuccessfull */
                        goto lookup;
                }
                
                if (error == ENOENT) {
                        goto err_exit;
                }
        }
        /* We have a name that matched */
        vp = *vpp;
        vpid = vp->v_id;

        /*
         * If this is a hard-link vnode then we need to update
         * the name (of the link), the parent ID, the cnid, the
         * text encoding and the catalog hint.  This enables
         * getattrlist calls to return the correct link info.
         */
        cp = VTOC(vp);
        if ((flags & ISLASTCN) && (cp->c_flag & C_HARDLINK) &&
             ((cp->c_parentcnid != VTOC(ap->a_dvp)->c_cnid) ||
              (bcmp(cnp->cn_nameptr, cp->c_desc.cd_nameptr, cp->c_desc.cd_namelen) != 0))) {
              
                struct cat_desc desc;

                /*
                 * Get an updated descriptor
                 */
                bzero(&desc, sizeof(desc));
                desc.cd_nameptr = cnp->cn_nameptr;
                desc.cd_namelen = cnp->cn_namelen;
                desc.cd_parentcnid = VTOC(ap->a_dvp)->c_cnid;
                desc.cd_hint = VTOC(ap->a_dvp)->c_childhint;
                if (cat_lookup(VTOHFS(vp), &desc, 0, &desc, NULL, NULL) == 0)
                        replace_desc(cp, &desc);
        }

        if (dvp == vp) {        /* lookup on "." */
                VREF(vp);
                error = 0;
        } else if (flags & ISDOTDOT) {
                /* 
                 * Carefull on the locking policy,
                 * remember we always lock from parent to child, so have
                 * to release lock on child before trying to lock parent
                 * then regain lock if needed
                 */
                VOP_UNLOCK(dvp, 0, p);
                error = vget(vp, LK_EXCLUSIVE, p);
                if (!error && lockparent && (flags & ISLASTCN))
                        error = vn_lock(dvp, LK_EXCLUSIVE, p);
        } else {
                if ((flags & ISLASTCN) == 0 && vp->v_type == VREG) {
                        int wantrsrc = 0;

                        cnp->cn_consume = forkcomponent(cnp, &wantrsrc);
                        if (cnp->cn_consume) {
                                flags |= ISLASTCN;
                                /* Fork names are only for lookups */
                                if (cnp->cn_nameiop != LOOKUP &&
                                    cnp->cn_nameiop != CREATE) {
                                        error = EPERM;

                                        goto err_exit;
                                }
                        }

                        if (wantrsrc) {
                                /* Use cnode's rsrcfork vnode (if available) */
                                if (cp->c_rsrc_vp != NULL) {
                                        *vpp = vp = cp->c_rsrc_vp;
                                        if (VNAME(vp) == NULL) {
                                            // the +1/-2 thing is to skip the leading "/" on the rsrc fork spec
                                            // and to not count the trailing null byte at the end of the string.
                                            VNAME(vp) = add_name(_PATH_RSRCFORKSPEC+1, sizeof(_PATH_RSRCFORKSPEC)-2, 0, 0);
                                        }
                                        if (VPARENT(vp) == NULL) {
                                            vget(cp->c_vp, 0, p);
                                            VPARENT(vp) = cp->c_vp;
                                        }
                                        vpid = vp->v_id;
                                } else {
                                        goto lookup;
                                }
                        }
                }
                error = vget(vp, 0, p);
                if (error == 0) {
                        if (VTOC(vp) == NULL || vp->v_data != (void *)cp) {
                                panic("hfs: cache lookup: my cnode disappeared/went bad! vp 0x%x 0x%x 0x%x\n",
                                          vp, vp->v_data, cp);
                        }
                        if (cnp->cn_nameiop == LOOKUP &&
                            (!(flags & ISLASTCN) || (flags & SHAREDLEAF)))
                                error = lockmgr(&VTOC(vp)->c_lock, LK_SHARED, NULL, p);
                        else
                                error = lockmgr(&VTOC(vp)->c_lock, LK_EXCLUSIVE, NULL, p);
                }
                if (!lockparent || error || !(flags & ISLASTCN)) {
                        (void) lockmgr(&dcp->c_lock, LK_RELEASE, NULL, p);
                }
        }
        /*
         * Check that the capability number did not change
         * while we were waiting for the lock.
         */
        if (!error) {
                if (vpid == vp->v_id)
                        return (0);
                /*
                 * The above is the NORMAL exit, after this point is an error
                 * condition.
                 */
                vput(vp);
                if (lockparent && (dvp != vp) && (flags & ISLASTCN))
                        VOP_UNLOCK(dvp, 0, p);
        }

        if ((error = vn_lock(dvp, LK_EXCLUSIVE, p)))
                return (error);
lookup:
        return (hfs_lookup(ap));

err_exit:
        *vpp = NULL;
        return (error);
}


/*
 * forkcomponent - look for a fork suffix in the component name
 *
 */
static int
forkcomponent(struct componentname *cnp, int *rsrcfork)
{
        char *suffix = cnp->cn_nameptr + cnp->cn_namelen;
        int consume = 0;

        *rsrcfork = 0;
        if (*suffix == '\0')
                return (0);
        /*
         * There are only 3 valid fork suffixes:
         *      "/..namedfork/rsrc"
         *      "/..namedfork/data"
         *      "/rsrc"  (legacy)
         */
        if (bcmp(suffix, _PATH_RSRCFORKSPEC, sizeof(_PATH_RSRCFORKSPEC)) == 0) {
                consume = sizeof(_PATH_RSRCFORKSPEC) - 1;
                *rsrcfork = 1;
        } else if (bcmp(suffix, _PATH_DATAFORKSPEC, sizeof(_PATH_DATAFORKSPEC)) == 0) {
                consume = sizeof(_PATH_DATAFORKSPEC) - 1;
        }

#ifdef LEGACY_FORK_NAMES
        else if (bcmp(suffix, LEGACY_RSRCFORKSPEC, sizeof(LEGACY_RSRCFORKSPEC)) == 0) {
                consume = sizeof(LEGACY_RSRCFORKSPEC) - 1;
                *rsrcfork = 1;
        }
#endif
        return (consume);
}