459 lines
14 KiB
C
459 lines
14 KiB
C
/*
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* Copyright (c) 1989 The Regents of the University of California.
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* All rights reserved.
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*
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* Copyright (c) 1983 Atsushi Murai (amurai@spec.co.jp)
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* All rights reserved for Rock Ridge Extension Support.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
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* $Id: isofs_lookup.c,v 1.13 1993/12/18 04:31:35 mycroft Exp $
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*/
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#include <sys/param.h>
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#include <sys/namei.h>
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#include <sys/buf.h>
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#include <sys/file.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <isofs/iso.h>
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#include <isofs/isofs_node.h>
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#include <isofs/iso_rrip.h>
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#include <isofs/isofs_rrip.h>
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struct nchstats iso_nchstats;
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/*
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* Convert a component of a pathname into a pointer to a locked inode.
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* This is a very central and rather complicated routine.
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* If the file system is not maintained in a strict tree hierarchy,
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* this can result in a deadlock situation (see comments in code below).
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*
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* The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
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* whether the name is to be looked up, created, renamed, or deleted.
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* When CREATE, RENAME, or DELETE is specified, information usable in
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* creating, renaming, or deleting a directory entry may be calculated.
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* If flag has LOCKPARENT or'ed into it and the target of the pathname
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* exists, lookup returns both the target and its parent directory locked.
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* When creating or renaming and LOCKPARENT is specified, the target may
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* not be ".". When deleting and LOCKPARENT is specified, the target may
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* be "."., but the caller must check to ensure it does an vrele and iput
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* instead of two iputs.
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*
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* Overall outline of ufs_lookup:
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*
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* check accessibility of directory
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* look for name in cache, if found, then if at end of path
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* and deleting or creating, drop it, else return name
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* search for name in directory, to found or notfound
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* notfound:
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* if creating, return locked directory, leaving info on available slots
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* else return error
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* found:
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* if at end of path and deleting, return information to allow delete
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* if at end of path and rewriting (RENAME and LOCKPARENT), lock target
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* inode and return info to allow rewrite
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* if not at end, add name to cache; if at end and neither creating
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* nor deleting, add name to cache
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*
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* NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
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*/
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isofs_lookup(vdp, ndp, p)
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register struct vnode *vdp;
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register struct nameidata *ndp;
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struct proc *p;
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{
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register struct iso_node *dp; /* the directory we are searching */
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register struct iso_mnt *imp; /* file system that directory is in */
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struct buf *bp = 0; /* a buffer of directory entries */
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struct iso_directory_record *ep;/* the current directory entry */
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off_t entryoffsetinblock; /* offset of ep in bp's buffer */
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off_t saveoffset; /* offset of last directory entry in dir */
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int numdirpasses; /* strategy for directory search */
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off_t endsearch; /* offset to end directory search */
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struct iso_node *pdp; /* saved dp during symlink work */
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struct iso_node *tdp; /* returned by iget */
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int flag; /* LOOKUP, CREATE, RENAME, or DELETE */
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int lockparent; /* 1 => lockparent flag is set */
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int wantparent; /* 1 => wantparent or lockparent flag */
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int error;
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ino_t ino = 0;
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int reclen;
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u_short namelen;
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char altname[NAME_MAX];
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int res;
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int assoc, len;
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char *name;
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ndp->ni_dvp = vdp;
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ndp->ni_vp = NULL;
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dp = VTOI(vdp);
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imp = dp->i_mnt;
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lockparent = ndp->ni_nameiop & LOCKPARENT;
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flag = ndp->ni_nameiop & OPMASK;
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wantparent = ndp->ni_nameiop & (LOCKPARENT|WANTPARENT);
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/*
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* Check accessiblity of directory.
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*/
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if (vdp->v_type != VDIR)
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return ENOTDIR;
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/*
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* We now have a segment name to search for, and a directory to search.
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*
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* Before tediously performing a linear scan of the directory,
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* check the name cache to see if the directory/name pair
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* we are looking for is known already.
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*/
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if (error = cache_lookup(ndp)) {
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int vpid; /* capability number of vnode */
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if (error == ENOENT)
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return (error);
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#ifdef PARANOID
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if (vdp == ndp->ni_rootdir && ndp->ni_isdotdot)
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panic("ufs_lookup: .. through root");
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#endif
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/*
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* Get the next vnode in the path.
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* See comment below starting `Step through' for
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* an explaination of the locking protocol.
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*/
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pdp = dp;
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dp = VTOI(ndp->ni_vp);
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vdp = ndp->ni_vp;
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vpid = vdp->v_id;
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if (pdp == dp) {
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VREF(vdp);
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error = 0;
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} else if (ndp->ni_isdotdot) {
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ISO_IUNLOCK(pdp);
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error = vget(vdp);
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if (!error && lockparent && *ndp->ni_next == '\0')
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ISO_ILOCK(pdp);
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} else {
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error = vget(vdp);
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if (!lockparent || error || *ndp->ni_next != '\0')
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ISO_IUNLOCK(pdp);
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}
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/*
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* Check that the capability number did not change
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* while we were waiting for the lock.
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*/
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if (!error) {
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if (vpid == vdp->v_id)
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return (0);
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iso_iput(dp);
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if (lockparent && pdp != dp && *ndp->ni_next == '\0')
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ISO_IUNLOCK(pdp);
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}
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ISO_ILOCK(pdp);
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dp = pdp;
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vdp = ITOV(dp);
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ndp->ni_vp = NULL;
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}
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len = ndp->ni_namelen;
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name = ndp->ni_ptr;
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/*
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* A leading `=' means, we are looking for an associated file
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*/
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if (assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)) {
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len--;
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name++;
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}
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/*
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* If there is cached information on a previous search of
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* this directory, pick up where we last left off.
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* We cache only lookups as these are the most common
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* and have the greatest payoff. Caching CREATE has little
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* benefit as it usually must search the entire directory
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* to determine that the entry does not exist. Caching the
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* location of the last DELETE or RENAME has not reduced
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* profiling time and hence has been removed in the interest
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* of simplicity.
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*/
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if (flag != LOOKUP || dp->i_diroff == 0 || dp->i_diroff > dp->i_size) {
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ndp->ni_ufs.ufs_offset = 0;
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numdirpasses = 1;
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} else {
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ndp->ni_ufs.ufs_offset = dp->i_diroff;
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entryoffsetinblock = iso_blkoff(imp, ndp->ni_ufs.ufs_offset);
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if (entryoffsetinblock != 0) {
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if (error = iso_blkatoff(dp,ndp->ni_ufs.ufs_offset,&bp))
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return error;
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}
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numdirpasses = 2;
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iso_nchstats.ncs_2passes++;
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}
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endsearch = roundup(dp->i_size,imp->logical_block_size);
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searchloop:
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while (ndp->ni_ufs.ufs_offset < endsearch) {
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/*
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* If offset is on a block boundary,
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* read the next directory block.
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* Release previous if it exists.
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*/
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if (iso_blkoff(imp,ndp->ni_ufs.ufs_offset) == 0) {
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if (bp != NULL)
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brelse(bp);
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if (error = iso_blkatoff(dp,ndp->ni_ufs.ufs_offset,&bp))
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return error;
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entryoffsetinblock = 0;
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}
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/*
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* Get pointer to next entry.
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*/
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ep = (struct iso_directory_record *)
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(bp->b_un.b_addr + entryoffsetinblock);
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reclen = isonum_711 (ep->length);
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if (reclen == 0) {
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/* skip to next block, if any */
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ndp->ni_ufs.ufs_offset =
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roundup(ndp->ni_ufs.ufs_offset,
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imp->logical_block_size);
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continue;
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}
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if (reclen < ISO_DIRECTORY_RECORD_SIZE)
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/* illegal entry, stop */
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break;
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if (entryoffsetinblock + reclen >= imp->logical_block_size)
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/* entries are not allowed to cross boundaries */
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break;
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/*
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* Check for a name match.
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*/
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namelen = isonum_711(ep->name_len);
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if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
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/* illegal entry, stop */
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break;
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switch (imp->iso_ftype) {
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default:
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if ((!(isonum_711(ep->flags)&4)) == !assoc) {
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if ((len == 1
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&& *name == '.')
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|| ndp->ni_isdotdot) {
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if (namelen == 1
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&& ep->name[0] == (ndp->ni_isdotdot ? 1 : 0)) {
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/*
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* Save directory entry's inode number and
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* reclen in ndp->ni_ufs area, and release
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* directory buffer.
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*/
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isodirino(&ndp->ni_ufs.ufs_ino,ep,imp);
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goto found;
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}
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if (namelen != 1
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|| ep->name[0] != 0)
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goto notfound;
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} else if (!(res = isofncmp(name,len,
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ep->name,namelen))) {
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if (isonum_711(ep->flags)&2)
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isodirino(&ino,ep,imp);
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else
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ino = (bp->b_blkno << DEV_BSHIFT)
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+ entryoffsetinblock;
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saveoffset = ndp->ni_ufs.ufs_offset;
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} else if (ino)
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goto foundino;
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#ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
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else if (res < 0)
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goto notfound;
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else if (res > 0 && numdirpasses == 2)
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numdirpasses++;
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#endif
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}
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break;
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case ISO_FTYPE_RRIP:
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if (isonum_711(ep->flags)&2)
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isodirino(&ino,ep,imp);
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else
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ino = (bp->b_blkno << DEV_BSHIFT) + entryoffsetinblock;
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ndp->ni_ufs.ufs_ino = ino;
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isofs_rrip_getname(ep,altname,&namelen,&ndp->ni_ufs.ufs_ino,imp);
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if (namelen == ndp->ni_namelen
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&& !bcmp(name,altname,namelen))
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goto found;
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ino = 0;
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break;
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}
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ndp->ni_ufs.ufs_offset += reclen;
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entryoffsetinblock += reclen;
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}
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if (ino) {
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foundino:
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ndp->ni_ufs.ufs_ino = ino;
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if (saveoffset != ndp->ni_ufs.ufs_offset) {
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if (iso_lblkno(imp,ndp->ni_ufs.ufs_offset)
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!= iso_lblkno(imp,saveoffset)) {
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if (bp != NULL)
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brelse(bp);
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if (error = iso_blkatoff(dp,saveoffset,&bp))
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return error;
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}
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ep = (struct iso_directory_record *)(bp->b_un.b_addr
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+ iso_blkoff(imp,saveoffset));
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ndp->ni_ufs.ufs_offset = saveoffset;
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}
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goto found;
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}
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notfound:
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/*
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* If we started in the middle of the directory and failed
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* to find our target, we must check the beginning as well.
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*/
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if (numdirpasses == 2) {
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numdirpasses--;
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ndp->ni_ufs.ufs_offset = 0;
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endsearch = dp->i_diroff;
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goto searchloop;
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}
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if (bp != NULL)
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brelse(bp);
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/*
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* Insert name into cache (as non-existent) if appropriate.
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*/
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if (ndp->ni_makeentry)
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cache_enter(ndp);
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if (flag == CREATE || flag == RENAME)
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return EJUSTRETURN;
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return (ENOENT);
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found:
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if (numdirpasses > 1)
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iso_nchstats.ncs_pass2++;
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/*
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* Found component in pathname.
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* If the final component of path name, save information
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* in the cache as to where the entry was found.
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*/
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if (*ndp->ni_next == '\0' && flag == LOOKUP)
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dp->i_diroff = ndp->ni_ufs.ufs_offset;
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/*
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* Step through the translation in the name. We do not `iput' the
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* directory because we may need it again if a symbolic link
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* is relative to the current directory. Instead we save it
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* unlocked as "pdp". We must get the target inode before unlocking
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* the directory to insure that the inode will not be removed
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* before we get it. We prevent deadlock by always fetching
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* inodes from the root, moving down the directory tree. Thus
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* when following backward pointers ".." we must unlock the
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* parent directory before getting the requested directory.
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* There is a potential race condition here if both the current
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* and parent directories are removed before the `iget' for the
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* inode associated with ".." returns. We hope that this occurs
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* infrequently since we cannot avoid this race condition without
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* implementing a sophisticated deadlock detection algorithm.
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* Note also that this simple deadlock detection scheme will not
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* work if the file system has any hard links other than ".."
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* that point backwards in the directory structure.
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*/
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pdp = dp;
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/*
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* If ino is different from ndp->ni_ufs.ufs_ino,
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* it's a relocated directory.
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*/
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if (ndp->ni_isdotdot) {
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ISO_IUNLOCK(pdp); /* race to get the inode */
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if (error = iso_iget(dp,ndp->ni_ufs.ufs_ino,
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ndp->ni_ufs.ufs_ino != ino,
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&tdp,ep)) {
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brelse(bp);
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ISO_ILOCK(pdp);
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return error;
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}
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if (lockparent && *ndp->ni_next == '\0')
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ISO_ILOCK(pdp);
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ndp->ni_vp = ITOV(tdp);
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} else if (dp->i_number == ndp->ni_ufs.ufs_ino) {
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VREF(vdp); /* we want ourself, ie "." */
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ndp->ni_vp = vdp;
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} else {
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if (error = iso_iget(dp,ndp->ni_ufs.ufs_ino,
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ndp->ni_ufs.ufs_ino != ino,
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&tdp,ep)) {
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brelse(bp);
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return error;
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}
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if (!lockparent || *ndp->ni_next != '\0')
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ISO_IUNLOCK(pdp);
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ndp->ni_vp = ITOV(tdp);
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}
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brelse(bp);
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/*
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* Insert name into cache if appropriate.
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*/
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if (ndp->ni_makeentry)
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cache_enter(ndp);
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return 0;
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}
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/*
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* Return buffer with contents of block "offset"
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* from the beginning of directory "ip". If "res"
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* is non-zero, fill it in with a pointer to the
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* remaining space in the directory.
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*/
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iso_blkatoff(ip, offset, bpp)
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struct iso_node *ip;
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off_t offset;
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struct buf **bpp;
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{
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register struct iso_mnt *imp = ip->i_mnt;
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daddr_t lbn = iso_lblkno(imp,offset);
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int bsize = iso_blksize(imp,ip,lbn);
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struct buf *bp;
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int error;
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if (error = bread(ITOV(ip),lbn,bsize,NOCRED,&bp)) {
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brelse(bp);
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*bpp = 0;
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return error;
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}
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*bpp = bp;
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return 0;
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}
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