492 lines
15 KiB
C
492 lines
15 KiB
C
/*-
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* Copyright (c) 1989, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley
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* by Pace Willisson (pace@blitz.com). The Rock Ridge Extension
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* Support code is derived from software contributed to Berkeley
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* by Atsushi Murai (amurai@spec.co.jp).
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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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*
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* @(#)cd9660_lookup.c 8.2 (Berkeley) 1/23/94
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* $Id: cd9660_lookup.c,v 1.15 1997/03/08 16:09:38 bde Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/namei.h>
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#include <sys/buf.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <isofs/cd9660/iso.h>
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#include <isofs/cd9660/cd9660_node.h>
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#include <isofs/cd9660/iso_rrip.h>
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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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int
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cd9660_lookup(ap)
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struct vop_lookup_args /* {
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struct vnode *a_dvp;
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struct vnode **a_vpp;
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struct componentname *a_cnp;
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} */ *ap;
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{
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register struct vnode *vdp; /* vnode for directory being searched */
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register struct iso_node *dp; /* inode for directory being searched */
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register struct iso_mnt *imp; /* file system that directory is in */
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struct buf *bp; /* a buffer of directory entries */
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struct iso_directory_record *ep = 0;/* the current directory entry */
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int entryoffsetinblock; /* offset of ep in bp's buffer */
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int saveoffset = 0; /* offset of last directory entry in dir */
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int numdirpasses; /* strategy for directory search */
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doff_t endsearch; /* offset to end directory search */
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struct vnode *pdp; /* saved dp during symlink work */
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struct vnode *tdp; /* returned by cd9660_vget_internal */
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u_long bmask; /* block offset mask */
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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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int isoflags;
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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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struct vnode **vpp = ap->a_vpp;
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struct componentname *cnp = ap->a_cnp;
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struct ucred *cred = cnp->cn_cred;
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int flags = cnp->cn_flags;
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int nameiop = cnp->cn_nameiop;
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struct proc *p = cnp->cn_proc;
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bp = NULL;
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*vpp = NULL;
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vdp = ap->a_dvp;
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dp = VTOI(vdp);
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imp = dp->i_mnt;
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lockparent = flags & LOCKPARENT;
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wantparent = flags & (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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if (error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc))
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return (error);
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if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
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(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
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return (EROFS);
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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(vdp, vpp, cnp))) {
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u_long 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->v_flag & VROOT) && (flags & ISDOTDOT))
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panic("cd9660_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 = vdp;
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dp = VTOI(*vpp);
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vdp = *vpp;
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vpid = vdp->v_id;
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if (pdp == vdp) {
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VREF(vdp);
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error = 0;
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} else if (flags & ISDOTDOT) {
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VOP_UNLOCK(pdp, 0, p);
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error = vget(vdp, LK_EXCLUSIVE, p);
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if (!error && lockparent && (flags & ISLASTCN))
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error = vn_lock(pdp, LK_EXCLUSIVE, p);
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} else {
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error = vget(vdp, LK_EXCLUSIVE, p);
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if (!lockparent || error || !(flags & ISLASTCN))
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VOP_UNLOCK(pdp, 0, p);
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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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vput(vdp);
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if (lockparent && pdp != vdp && (flags & ISLASTCN))
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VOP_UNLOCK(pdp, 0, p);
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}
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if (error = vn_lock(pdp, LK_EXCLUSIVE, p))
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return (error);
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vdp = pdp;
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dp = VTOI(pdp);
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*vpp = NULL;
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}
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len = cnp->cn_namelen;
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name = cnp->cn_nameptr;
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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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{
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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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bmask = imp->im_bmask;
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if (nameiop != LOOKUP || dp->i_diroff == 0 ||
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dp->i_diroff > dp->i_size) {
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entryoffsetinblock = 0;
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dp->i_offset = 0;
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numdirpasses = 1;
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} else {
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dp->i_offset = dp->i_diroff;
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if ((entryoffsetinblock = dp->i_offset & bmask) &&
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(error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)))
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return (error);
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numdirpasses = 2;
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nchstats.ncs_2passes++;
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}
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endsearch = dp->i_size;
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searchloop:
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while (dp->i_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 ((dp->i_offset & bmask) == 0) {
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if (bp != NULL)
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brelse(bp);
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if (error =
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VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &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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((char *)bp->b_data + 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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dp->i_offset =
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(dp->i_offset & ~bmask) + 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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namelen = isonum_711(ep->name_len);
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isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA?
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&ep->date[6]: ep->flags);
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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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/*
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* Check for a name match.
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*/
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switch (imp->iso_ftype) {
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default:
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if (!(isoflags & 4) == !assoc) {
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if ((len == 1
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&& *name == '.')
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|| (flags & ISDOTDOT)) {
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if (namelen == 1
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&& ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
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/*
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* Save directory entry's inode number and
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* release directory buffer.
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*/
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dp->i_ino = isodirino(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 (isoflags & 2)
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ino = isodirino(ep, imp);
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else
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ino = dbtob(bp->b_blkno)
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+ entryoffsetinblock;
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saveoffset = dp->i_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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ino = isodirino(ep, imp);
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else
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ino = dbtob(bp->b_blkno) + entryoffsetinblock;
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dp->i_ino = ino;
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cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
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if (namelen == cnp->cn_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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dp->i_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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dp->i_ino = ino;
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if (saveoffset != dp->i_offset) {
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if (lblkno(imp, dp->i_offset) !=
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lblkno(imp, saveoffset)) {
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if (bp != NULL)
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brelse(bp);
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if (error = VOP_BLKATOFF(vdp,
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(off_t)saveoffset, NULL, &bp))
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return (error);
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}
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entryoffsetinblock = saveoffset & bmask;
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ep = (struct iso_directory_record *)
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((char *)bp->b_data + entryoffsetinblock);
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dp->i_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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dp->i_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 (cnp->cn_flags & MAKEENTRY)
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cache_enter(vdp, *vpp, cnp);
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if (nameiop == CREATE || nameiop == RENAME)
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return (EROFS);
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return (ENOENT);
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found:
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if (numdirpasses == 2)
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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 ((flags & ISLASTCN) && nameiop == LOOKUP)
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dp->i_diroff = dp->i_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 = vdp;
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/*
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* If ino is different from dp->i_ino,
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* it's a relocated directory.
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*/
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if (flags & ISDOTDOT) {
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VOP_UNLOCK(pdp, 0, p); /* race to get the inode */
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error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
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dp->i_ino != ino, ep);
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brelse(bp);
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if (error) {
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vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p);
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return (error);
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}
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if (lockparent && (flags & ISLASTCN) &&
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(error = vn_lock(pdp, LK_EXCLUSIVE, p))) {
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vput(tdp);
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return (error);
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}
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*vpp = tdp;
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} else if (dp->i_number == dp->i_ino) {
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brelse(bp);
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VREF(vdp); /* we want ourself, ie "." */
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*vpp = vdp;
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} else {
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error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
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dp->i_ino != ino, ep);
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brelse(bp);
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if (error)
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return (error);
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if (!lockparent || !(flags & ISLASTCN))
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VOP_UNLOCK(pdp, 0, p);
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*vpp = tdp;
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}
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/*
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* Insert name into cache if appropriate.
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*/
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if (cnp->cn_flags & MAKEENTRY)
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cache_enter(vdp, *vpp, cnp);
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return (0);
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}
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/*
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* Return buffer with the contents of block "offset" from the beginning of
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* directory "ip". If "res" 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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int
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cd9660_blkatoff(ap)
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struct vop_blkatoff_args /* {
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struct vnode *a_vp;
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off_t a_offset;
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char **a_res;
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struct buf **a_bpp;
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} */ *ap;
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{
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struct iso_node *ip;
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register struct iso_mnt *imp;
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struct buf *bp;
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daddr_t lbn;
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int bsize, error;
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ip = VTOI(ap->a_vp);
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imp = ip->i_mnt;
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lbn = lblkno(imp, ap->a_offset);
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bsize = blksize(imp, ip, lbn);
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if (error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) {
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brelse(bp);
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*ap->a_bpp = NULL;
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return (error);
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}
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if (ap->a_res)
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*ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset);
|
|
*ap->a_bpp = bp;
|
|
return (0);
|
|
}
|