msdosfs_lookup.c revision 3152
1/*	$Id: msdosfs_lookup.c,v 1.1 1994/09/19 15:41:44 dfr Exp $ */
2/*	$NetBSD: msdosfs_lookup.c,v 1.14 1994/08/21 18:44:07 ws Exp $	*/
3
4/*-
5 * Copyright (C) 1994 Wolfgang Solfrank.
6 * Copyright (C) 1994 TooLs GmbH.
7 * All rights reserved.
8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by TooLs GmbH.
21 * 4. The name of TooLs GmbH may not be used to endorse or promote products
22 *    derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
30 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35/*
36 * Written by Paul Popelka (paulp@uts.amdahl.com)
37 *
38 * You can do anything you want with this software, just don't say you wrote
39 * it, and don't remove this notice.
40 *
41 * This software is provided "as is".
42 *
43 * The author supplies this software to be publicly redistributed on the
44 * understanding that the author is not responsible for the correct
45 * functioning of this software in any circumstances and is not liable for
46 * any damages caused by this software.
47 *
48 * October 1992
49 */
50
51#include <sys/param.h>
52#include <sys/namei.h>
53#include <sys/buf.h>
54#include <sys/vnode.h>
55#include <sys/mount.h>
56#include <sys/systm.h>
57
58#include <msdosfs/bpb.h>
59#include <msdosfs/direntry.h>
60#include <msdosfs/denode.h>
61#include <msdosfs/msdosfsmount.h>
62#include <msdosfs/fat.h>
63
64/*
65 * When we search a directory the blocks containing directory entries are
66 * read and examined.  The directory entries contain information that would
67 * normally be in the inode of a unix filesystem.  This means that some of
68 * a directory's contents may also be in memory resident denodes (sort of
69 * an inode).  This can cause problems if we are searching while some other
70 * process is modifying a directory.  To prevent one process from accessing
71 * incompletely modified directory information we depend upon being the
72 * soul owner of a directory block.  bread/brelse provide this service.
73 * This being the case, when a process modifies a directory it must first
74 * acquire the disk block that contains the directory entry to be modified.
75 * Then update the disk block and the denode, and then write the disk block
76 * out to disk.  This way disk blocks containing directory entries and in
77 * memory denode's will be in synch.
78 */
79int
80msdosfs_lookup(ap)
81	struct vop_lookup_args /* {
82		struct vnode *a_dvp;
83		struct vnode **a_vpp;
84		struct componentname *a_cnp;
85	} */ *ap;
86{
87	struct vnode *vdp = ap->a_dvp;
88	struct vnode **vpp = ap->a_vpp;
89	struct componentname *cnp = ap->a_cnp;
90	daddr_t bn;
91	int error;
92	int lockparent;
93	int wantparent;
94	int slotstatus;
95
96#define	NONE	0
97#define	FOUND	1
98	int slotoffset = -1;
99	int slotcluster = -1;
100	int frcn;
101	u_long cluster;
102	int rootreloff;
103	int diroff;
104	int isadir;		/* ~0 if found direntry is a directory	 */
105	u_long scn;		/* starting cluster number		 */
106	struct vnode *pdp;
107	struct denode *dp;
108	struct denode *tdp;
109	struct msdosfsmount *pmp;
110	struct buf *bp = 0;
111	struct direntry *dep = NULL;
112	u_char dosfilename[12];
113	int flags = cnp->cn_flags;
114	int nameiop = cnp->cn_nameiop;
115
116#ifdef MSDOSFS_DEBUG
117	printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
118#endif
119	dp = VTODE(vdp);
120	pmp = dp->de_pmp;
121	*vpp = NULL;
122	lockparent = flags & LOCKPARENT;
123	wantparent = flags & (LOCKPARENT | WANTPARENT);
124#ifdef MSDOSFS_DEBUG
125	printf("msdosfs_lookup(): vdp %08x, dp %08x, Attr %02x\n",
126	       vdp, dp, dp->de_Attributes);
127#endif
128
129	/*
130	 * Be sure vdp is a directory.  Since dos filesystems don't have
131	 * the concept of execute permission anybody can search a
132	 * directory.
133	 */
134	if ((dp->de_Attributes & ATTR_DIRECTORY) == 0)
135		return ENOTDIR;
136
137	/*
138	 * See if the component of the pathname we are looking for is in
139	 * the directory cache.  If so then do a few things and return.
140	 */
141	error = cache_lookup(vdp, vpp, cnp);
142	if (error) {
143		int vpid;
144
145		if (error == ENOENT)
146			return error;
147		pdp = vdp;
148		vdp = *vpp;
149		dp = VTODE(vdp);
150		vpid = vdp->v_id;
151		if (pdp == vdp) {
152			VREF(vdp);
153			error = 0;
154		} else if (flags & ISDOTDOT) {
155			VOP_UNLOCK(pdp);
156			error = vget(vdp, 1);
157			if (!error && lockparent && (flags & ISLASTCN))
158				error = VOP_LOCK(pdp);
159		} else {
160			error = vget(vdp, 1);
161			if (!lockparent || error || !(flags & ISLASTCN))
162				VOP_UNLOCK(pdp);
163		}
164
165		if (!error) {
166			if (vpid == vdp->v_id) {
167#ifdef MSDOSFS_DEBUG
168				printf("msdosfs_lookup(): cache hit, vnode %08x, file %s\n",
169				       vdp, dp->de_Name);
170#endif
171				return 0;
172			}
173			vput(vdp);
174			if (lockparent && pdp != vdp && (flags & ISLASTCN))
175				VOP_UNLOCK(pdp);
176		}
177		error = VOP_LOCK(pdp);
178		if (error)
179			return error;
180		vdp = pdp;
181		dp = VTODE(vdp);
182		*vpp = NULL;
183	}
184
185	/*
186	 * If they are going after the . or .. entry in the root directory,
187	 * they won't find it.  DOS filesystems don't have them in the root
188	 * directory.  So, we fake it. deget() is in on this scam too.
189	 */
190	if ((vdp->v_flag & VROOT) && cnp->cn_nameptr[0] == '.' &&
191	    (cnp->cn_namelen == 1 ||
192		(cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
193		isadir = ATTR_DIRECTORY;
194		scn = MSDOSFSROOT;
195#ifdef MSDOSFS_DEBUG
196		printf("msdosfs_lookup(): looking for . or .. in root directory\n");
197#endif
198		cluster = MSDOSFSROOT;
199		diroff = MSDOSFSROOT_OFS;
200		goto foundroot;
201	}
202
203	/*
204	 * Don't search for free slots unless we are creating a filename
205	 * and we are at the end of the pathname.
206	 */
207	slotstatus = FOUND;
208	if ((nameiop == CREATE || nameiop == RENAME) && (flags & ISLASTCN)) {
209		slotstatus = NONE;
210		slotoffset = -1;
211	}
212
213	unix2dosfn((u_char *) cnp->cn_nameptr, dosfilename, cnp->cn_namelen);
214	dosfilename[11] = 0;
215#ifdef MSDOSFS_DEBUG
216	printf("msdosfs_lookup(): dos version of filename %s, length %d\n",
217	       dosfilename, cnp->cn_namelen);
218#endif
219	/*
220	 * Search the directory pointed at by vdp for the name pointed at
221	 * by cnp->cn_nameptr.
222	 */
223	tdp = NULL;
224	/*
225	 * The outer loop ranges over the clusters that make up the
226	 * directory.  Note that the root directory is different from all
227	 * other directories.  It has a fixed number of blocks that are not
228	 * part of the pool of allocatable clusters.  So, we treat it a
229	 * little differently. The root directory starts at "cluster" 0.
230	 */
231	rootreloff = 0;
232	for (frcn = 0;; frcn++) {
233		error = pcbmap(dp, frcn, &bn, &cluster);
234		if (error) {
235			if (error == E2BIG)
236				break;
237			return error;
238		}
239		error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster,NOCRED,&bp);
240		if (error)
241			return error;
242		for (diroff = 0; diroff < pmp->pm_depclust; diroff++) {
243			dep = (struct direntry *) bp->b_data + diroff;
244
245			/*
246			 * If the slot is empty and we are still looking
247			 * for an empty then remember this one.  If the
248			 * slot is not empty then check to see if it
249			 * matches what we are looking for.  If the slot
250			 * has never been filled with anything, then the
251			 * remainder of the directory has never been used,
252			 * so there is no point in searching it.
253			 */
254			if (dep->deName[0] == SLOT_EMPTY ||
255			    dep->deName[0] == SLOT_DELETED) {
256				if (slotstatus != FOUND) {
257					slotstatus = FOUND;
258					if (cluster == MSDOSFSROOT)
259						slotoffset = rootreloff;
260					else
261						slotoffset = diroff;
262					slotcluster = cluster;
263				}
264				if (dep->deName[0] == SLOT_EMPTY) {
265					brelse(bp);
266					goto notfound;
267				}
268			} else {
269				/*
270				 * Ignore volume labels (anywhere, not just
271				 * the root directory).
272				 */
273				if ((dep->deAttributes & ATTR_VOLUME) == 0 &&
274				    bcmp(dosfilename, dep->deName, 11) == 0) {
275#ifdef MSDOSFS_DEBUG
276					printf("msdosfs_lookup(): match diroff %d, rootreloff %d\n",
277					       diroff, rootreloff);
278#endif
279					/*
280					 * Remember where this directory
281					 * entry came from for whoever did
282					 * this lookup. If this is the root
283					 * directory we are interested in
284					 * the offset relative to the
285					 * beginning of the directory (not
286					 * the beginning of the cluster).
287					 */
288					if (cluster == MSDOSFSROOT)
289						diroff = rootreloff;
290					dp->de_fndoffset = diroff;
291					dp->de_fndclust = cluster;
292					goto found;
293				}
294			}
295			rootreloff++;
296		}		/* for (diroff = 0; .... */
297		/*
298		 * Release the buffer holding the directory cluster just
299		 * searched.
300		 */
301		brelse(bp);
302	}			/* for (frcn = 0; ; frcn++) */
303notfound:;
304	/*
305	 * We hold no disk buffers at this point.
306	 */
307
308	/*
309	 * If we get here we didn't find the entry we were looking for. But
310	 * that's ok if we are creating or renaming and are at the end of
311	 * the pathname and the directory hasn't been removed.
312	 */
313#ifdef MSDOSFS_DEBUG
314	printf("msdosfs_lookup(): op %d, refcnt %d, slotstatus %d\n",
315	       nameiop, dp->de_refcnt, slotstatus);
316	printf("               slotoffset %d, slotcluster %d\n",
317	       slotoffset, slotcluster);
318#endif
319	if ((nameiop == CREATE || nameiop == RENAME) &&
320	    (flags & ISLASTCN) && dp->de_refcnt != 0) {
321		if (slotstatus == NONE) {
322			dp->de_fndoffset = (u_long)-1;
323			dp->de_fndclust = (u_long)-1;
324		} else {
325#ifdef MSDOSFS_DEBUG
326			printf("msdosfs_lookup(): saving empty slot location\n");
327#endif
328			dp->de_fndoffset = slotoffset;
329			dp->de_fndclust = slotcluster;
330		}
331		/* dp->de_flag |= DE_UPDATE;  never update dos directories */
332		cnp->cn_flags |= SAVENAME;
333		if (!lockparent)/* leave searched dir locked?	 */
334			VOP_UNLOCK(vdp);
335		return EJUSTRETURN;
336	}
337	/*
338	 * Insert name in cache as non-existant if not trying to create it.
339	 */
340	if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
341		cache_enter(vdp, *vpp, cnp);
342	return ENOENT;
343
344found:	;
345	/*
346	 * NOTE:  We still have the buffer with matched directory entry at
347	 * this point.
348	 */
349	isadir = dep->deAttributes & ATTR_DIRECTORY;
350	scn = getushort(dep->deStartCluster);
351
352foundroot:;
353	/*
354	 * If we entered at foundroot, then we are looking for the . or ..
355	 * entry of the filesystems root directory.  isadir and scn were
356	 * setup before jumping here.  And, bp is null.  There is no buf
357	 * header.
358	 */
359
360	/*
361	 * If deleting and at the end of the path, then if we matched on
362	 * "." then don't deget() we would probably panic().  Otherwise
363	 * deget() the directory entry.
364	 */
365	if (nameiop == DELETE && (flags & ISLASTCN)) {
366		if (dp->de_StartCluster == scn && isadir) {	/* "." */
367			VREF(vdp);
368			*vpp = vdp;
369			if (bp)
370				brelse(bp);
371			return 0;
372		}
373		error = deget(pmp, cluster, diroff, dep, &tdp);
374		if (error) {
375			if (bp)
376				brelse(bp);
377			return error;
378		}
379		*vpp = DETOV(tdp);
380		if (!lockparent)
381			VOP_UNLOCK(vdp);
382		if (bp)
383			brelse(bp);
384		return 0;
385	}
386
387	/*
388	 * If renaming.
389	 */
390	if (nameiop == RENAME && wantparent && (flags & ISLASTCN)) {
391		if (dp->de_StartCluster == scn && isadir) {
392			if (bp)
393				brelse(bp);
394			return EISDIR;
395		}
396		error = deget(pmp, cluster, diroff, dep, &tdp);
397		if (error) {
398			if (bp)
399				brelse(bp);
400			return error;
401		}
402		*vpp = DETOV(tdp);
403		cnp->cn_flags |= SAVENAME;
404		if (!lockparent)
405			VOP_UNLOCK(vdp);
406		if (bp)
407			brelse(bp);
408		return 0;
409	}
410
411	/*
412	 * ?
413	 */
414	pdp = vdp;
415	if (flags & ISDOTDOT) {
416		VOP_UNLOCK(pdp);
417		error = deget(pmp, cluster, diroff, dep, &tdp);
418		if (error) {
419			VOP_LOCK(pdp);
420			if (bp)
421				brelse(bp);
422			return error;
423		}
424		if (lockparent && (flags & ISLASTCN)
425		    && (error = VOP_LOCK(pdp))) {
426			vput(DETOV(tdp));
427			return error;
428		}
429		*vpp = DETOV(tdp);
430	} else if (dp->de_StartCluster == scn && isadir) {		/* "." */
431		VREF(vdp);
432		*vpp = vdp;
433	} else {
434		error = deget(pmp, cluster, diroff, dep, &tdp);
435		if (error) {
436			if (bp)
437				brelse(bp);
438			return error;
439		}
440		if (!lockparent || !(flags & ISLASTCN))
441			VOP_UNLOCK(pdp);
442		*vpp = DETOV(tdp);
443	}
444	if (bp)
445		brelse(bp);
446
447	/*
448	 * Insert name in cache if wanted.
449	 */
450	if (cnp->cn_flags & MAKEENTRY)
451		cache_enter(vdp, *vpp, cnp);
452	return 0;
453}
454
455/*
456 * dep  - directory entry to copy into the directory
457 * ddep - directory to add to
458 * depp - return the address of the denode for the created directory entry
459 *	  if depp != 0
460 */
461int
462createde(dep, ddep, depp)
463	struct denode *dep;
464	struct denode *ddep;
465	struct denode **depp;
466{
467	int error;
468	u_long dirclust, diroffset;
469	struct direntry *ndep;
470	struct msdosfsmount *pmp = ddep->de_pmp;
471	struct buf *bp;
472
473#ifdef MSDOSFS_DEBUG
474	printf("createde(dep %08x, ddep %08x, depp %08x)\n", dep, ddep, depp);
475#endif
476
477	/*
478	 * If no space left in the directory then allocate another cluster
479	 * and chain it onto the end of the file.  There is one exception
480	 * to this.  That is, if the root directory has no more space it
481	 * can NOT be expanded.  extendfile() checks for and fails attempts
482	 * to extend the root directory.  We just return an error in that
483	 * case.
484	 */
485	if (ddep->de_fndclust == (u_long)-1) {
486		error = extendfile(ddep, 1, &bp, &dirclust, DE_CLEAR);
487		if (error)
488			return error;
489		ndep = (struct direntry *) bp->b_data;
490		/*
491		 * Let caller know where we put the directory entry.
492		 */
493		ddep->de_fndclust = dirclust;
494		ddep->de_fndoffset = diroffset = 0;
495		/*
496		 * Update the size of the directory
497		 */
498		ddep->de_FileSize += pmp->pm_bpcluster;
499	} else {
500		/*
501		 * There is space in the existing directory.  So, we just
502		 * read in the cluster with space.  Copy the new directory
503		 * entry in.  Then write it to disk. NOTE:  DOS directories
504		 * do not get smaller as clusters are emptied.
505		 */
506		dirclust = ddep->de_fndclust;
507		diroffset = ddep->de_fndoffset;
508
509		error = readep(pmp, dirclust, diroffset, &bp, &ndep);
510		if (error)
511			return error;
512	}
513	DE_EXTERNALIZE(ndep, dep);
514
515	/*
516	 * If they want us to return with the denode gotten.
517	 */
518	if (depp) {
519		error = deget(pmp, dirclust, diroffset, ndep, depp);
520		if (error)
521			return error;
522	}
523	error = bwrite(bp);
524	if (error) {
525		vput(DETOV(*depp));	/* free the vnode we got on error */
526		return error;
527	}
528	return 0;
529}
530
531/*
532 * Read in a directory entry and mark it as being deleted.
533 */
534int
535markdeleted(pmp, dirclust, diroffset)
536	struct msdosfsmount *pmp;
537	u_long dirclust;
538	u_long diroffset;
539{
540	int error;
541	struct direntry *ep;
542	struct buf *bp;
543
544	error = readep(pmp, dirclust, diroffset, &bp, &ep);
545	if (error)
546		return error;
547	ep->deName[0] = SLOT_DELETED;
548	return bwrite(bp);
549}
550
551/*
552 * Remove a directory entry. At this point the file represented by the
553 * directory entry to be removed is still full length until no one has it
554 * open.  When the file no longer being used msdosfs_inactive() is called
555 * and will truncate the file to 0 length.  When the vnode containing the
556 * denode is needed for some other purpose by VFS it will call
557 * msdosfs_reclaim() which will remove the denode from the denode cache.
558 */
559int
560removede(pdep,dep)
561	struct denode *pdep;	/* directory where the entry is removed */
562	struct denode *dep;	/* file to be removed */
563{
564	struct msdosfsmount *pmp = pdep->de_pmp;
565	int error;
566
567#ifdef MSDOSFS_DEBUG
568	printf("removede(): filename %s\n", dep->de_Name);
569	printf("removede(): dep %08x, ndpcluster %d, ndpoffset %d\n",
570	       dep, pdep->de_fndclust, pdep->de_fndoffset);
571#endif
572
573	/*
574	 * Read the directory block containing the directory entry we are
575	 * to make free.  The nameidata structure holds the cluster number
576	 * and directory entry index number of the entry to free.
577	 */
578	error = markdeleted(pmp, pdep->de_fndclust, pdep->de_fndoffset);
579
580	if (error == 0)
581		dep->de_refcnt--;
582	return error;
583}
584
585/*
586 * Be sure a directory is empty except for "." and "..". Return 1 if empty,
587 * return 0 if not empty or error.
588 */
589int
590dosdirempty(dep)
591	struct denode *dep;
592{
593	int dei;
594	int error;
595	u_long cn;
596	daddr_t bn;
597	struct buf *bp;
598	struct msdosfsmount *pmp = dep->de_pmp;
599	struct direntry *dentp;
600
601	/*
602	 * Since the filesize field in directory entries for a directory is
603	 * zero, we just have to feel our way through the directory until
604	 * we hit end of file.
605	 */
606	for (cn = 0;; cn++) {
607		error = pcbmap(dep, cn, &bn, 0);
608		if (error == E2BIG)
609			return 1;	/* it's empty */
610		error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, NOCRED,
611		    &bp);
612		if (error)
613			return error;
614		dentp = (struct direntry *) bp->b_data;
615		for (dei = 0; dei < pmp->pm_depclust; dei++) {
616			if (dentp->deName[0] != SLOT_DELETED) {
617				/*
618				 * In dos directories an entry whose name
619				 * starts with SLOT_EMPTY (0) starts the
620				 * beginning of the unused part of the
621				 * directory, so we can just return that it
622				 * is empty.
623				 */
624				if (dentp->deName[0] == SLOT_EMPTY) {
625					brelse(bp);
626					return 1;
627				}
628				/*
629				 * Any names other than "." and ".." in a
630				 * directory mean it is not empty.
631				 */
632				if (bcmp(dentp->deName, ".          ", 11) &&
633				    bcmp(dentp->deName, "..         ", 11)) {
634					brelse(bp);
635#ifdef MSDOSFS_DEBUG
636					printf("dosdirempty(): entry %d found %02x, %02x\n",
637					       dei, dentp->deName[0], dentp->deName[1]);
638#endif
639					return 0;	/* not empty */
640				}
641			}
642			dentp++;
643		}
644		brelse(bp);
645	}
646	/* NOTREACHED */
647}
648
649/*
650 * Check to see if the directory described by target is in some
651 * subdirectory of source.  This prevents something like the following from
652 * succeeding and leaving a bunch or files and directories orphaned. mv
653 * /a/b/c /a/b/c/d/e/f Where c and f are directories.
654 *
655 * source - the inode for /a/b/c
656 * target - the inode for /a/b/c/d/e/f
657 *
658 * Returns 0 if target is NOT a subdirectory of source.
659 * Otherwise returns a non-zero error number.
660 * The target inode is always unlocked on return.
661 */
662int
663doscheckpath(source, target)
664	struct denode *source;
665	struct denode *target;
666{
667	daddr_t scn;
668	struct msdosfsmount *pmp;
669	struct direntry *ep;
670	struct denode *dep;
671	struct buf *bp = NULL;
672	int error = 0;
673
674	dep = target;
675	if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
676	    (source->de_Attributes & ATTR_DIRECTORY) == 0) {
677		error = ENOTDIR;
678		goto out;
679	}
680	if (dep->de_StartCluster == source->de_StartCluster) {
681		error = EEXIST;
682		goto out;
683	}
684	if (dep->de_StartCluster == MSDOSFSROOT)
685		goto out;
686	for (;;) {
687		if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
688			error = ENOTDIR;
689			goto out;
690		}
691		pmp = dep->de_pmp;
692		scn = dep->de_StartCluster;
693		error = bread(pmp->pm_devvp, cntobn(pmp, scn),
694		    pmp->pm_bpcluster, NOCRED, &bp);
695		if (error) {
696			break;
697		}
698		ep = (struct direntry *) bp->b_data + 1;
699		if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
700		    bcmp(ep->deName, "..         ", 11) != 0) {
701			error = ENOTDIR;
702			break;
703		}
704		scn = getushort(ep->deStartCluster);
705		if (scn == source->de_StartCluster) {
706			error = EINVAL;
707			break;
708		}
709		if (scn == MSDOSFSROOT)
710			break;
711		vput(DETOV(dep));
712		/* NOTE: deget() clears dep on error */
713		error = deget(pmp, scn, 0, ep, &dep);
714		brelse(bp);
715		bp = NULL;
716		if (error)
717			break;
718	}
719out:	;
720	if (bp)
721		brelse(bp);
722	if (error == ENOTDIR)
723		printf("doscheckpath(): .. not a directory?\n");
724	if (dep != NULL)
725		vput(DETOV(dep));
726	return error;
727}
728
729/*
730 * Read in the disk block containing the directory entry (dirclu, dirofs)
731 * and return the address of the buf header, and the address of the
732 * directory entry within the block.
733 */
734int
735readep(pmp, dirclu, dirofs, bpp, epp)
736	struct msdosfsmount *pmp;
737	u_long dirclu, dirofs;
738	struct buf **bpp;
739	struct direntry **epp;
740{
741	int error;
742	daddr_t bn;
743
744	bn = detobn(pmp, dirclu, dirofs);
745	error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, NOCRED, bpp);
746	if (error) {
747		*bpp = NULL;
748		return error;
749	}
750	if (epp)
751		*epp = bptoep(pmp, *bpp, dirofs);
752	return 0;
753}
754
755
756/*
757 * Read in the disk block containing the directory entry dep came from and
758 * return the address of the buf header, and the address of the directory
759 * entry within the block.
760 */
761int
762readde(dep, bpp, epp)
763	struct denode *dep;
764	struct buf **bpp;
765	struct direntry **epp;
766{
767	return readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
768	    bpp, epp);
769}
770