xref: /freebsd/sys/fs/msdosfs/msdosfs_lookup.c (revision 4f52dfbb8d6c4d446500c5b097e3806ec219fbd4)
1 /* $FreeBSD$ */
2 /*	$NetBSD: msdosfs_lookup.c,v 1.37 1997/11/17 15:36:54 ws Exp $	*/
3 
4 /*-
5  * SPDX-License-Identifier: BSD-4-Clause
6  *
7  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
8  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
9  * All rights reserved.
10  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by TooLs GmbH.
23  * 4. The name of TooLs GmbH may not be used to endorse or promote products
24  *    derived from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
32  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
33  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
34  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  */
37 /*-
38  * Written by Paul Popelka (paulp@uts.amdahl.com)
39  *
40  * You can do anything you want with this software, just don't say you wrote
41  * it, and don't remove this notice.
42  *
43  * This software is provided "as is".
44  *
45  * The author supplies this software to be publicly redistributed on the
46  * understanding that the author is not responsible for the correct
47  * functioning of this software in any circumstances and is not liable for
48  * any damages caused by this software.
49  *
50  * October 1992
51  */
52 
53 #include <sys/param.h>
54 #include <sys/systm.h>
55 #include <sys/buf.h>
56 #include <sys/mount.h>
57 #include <sys/namei.h>
58 #include <sys/vnode.h>
59 
60 #include <fs/msdosfs/bpb.h>
61 #include <fs/msdosfs/direntry.h>
62 #include <fs/msdosfs/denode.h>
63 #include <fs/msdosfs/fat.h>
64 #include <fs/msdosfs/msdosfsmount.h>
65 
66 static int msdosfs_lookup_(struct vnode *vdp, struct vnode **vpp,
67     struct componentname *cnp, uint64_t *inum);
68 
69 int
70 msdosfs_lookup(struct vop_cachedlookup_args *ap)
71 {
72 
73 	return (msdosfs_lookup_(ap->a_dvp, ap->a_vpp, ap->a_cnp, NULL));
74 }
75 
76 struct deget_dotdot {
77 	u_long cluster;
78 	int blkoff;
79 };
80 
81 static int
82 msdosfs_deget_dotdot(struct mount *mp, void *arg, int lkflags,
83     struct vnode **rvp)
84 {
85 	struct deget_dotdot *dd_arg;
86 	struct denode *rdp;
87 	struct msdosfsmount *pmp;
88 	int error;
89 
90 	pmp = VFSTOMSDOSFS(mp);
91 	dd_arg = arg;
92 	error = deget(pmp, dd_arg->cluster, dd_arg->blkoff,  &rdp);
93 	if (error == 0)
94 		*rvp = DETOV(rdp);
95 	return (error);
96 }
97 
98 /*
99  * When we search a directory the blocks containing directory entries are
100  * read and examined.  The directory entries contain information that would
101  * normally be in the inode of a unix filesystem.  This means that some of
102  * a directory's contents may also be in memory resident denodes (sort of
103  * an inode).  This can cause problems if we are searching while some other
104  * process is modifying a directory.  To prevent one process from accessing
105  * incompletely modified directory information we depend upon being the
106  * sole owner of a directory block.  bread/brelse provide this service.
107  * This being the case, when a process modifies a directory it must first
108  * acquire the disk block that contains the directory entry to be modified.
109  * Then update the disk block and the denode, and then write the disk block
110  * out to disk.  This way disk blocks containing directory entries and in
111  * memory denode's will be in synch.
112  */
113 static int
114 msdosfs_lookup_(struct vnode *vdp, struct vnode **vpp,
115     struct componentname *cnp, uint64_t *dd_inum)
116 {
117 	struct mbnambuf nb;
118 	daddr_t bn;
119 	int error;
120 	int slotcount;
121 	int slotoffset = 0;
122 	int frcn;
123 	u_long cluster;
124 	int blkoff;
125 	int diroff;
126 	int blsize;
127 	int isadir;		/* ~0 if found direntry is a directory	 */
128 	u_long scn;		/* starting cluster number		 */
129 	struct vnode *pdp;
130 	struct denode *dp;
131 	struct denode *tdp;
132 	struct msdosfsmount *pmp;
133 	struct buf *bp = NULL;
134 	struct direntry *dep = NULL;
135 	struct deget_dotdot dd_arg;
136 	u_char dosfilename[12];
137 	int flags = cnp->cn_flags;
138 	int nameiop = cnp->cn_nameiop;
139 	int unlen;
140 	uint64_t inode1;
141 
142 	int wincnt = 1;
143 	int chksum = -1, chksum_ok;
144 	int olddos = 1;
145 
146 #ifdef MSDOSFS_DEBUG
147 	printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
148 #endif
149 	dp = VTODE(vdp);
150 	pmp = dp->de_pmp;
151 #ifdef MSDOSFS_DEBUG
152 	printf("msdosfs_lookup(): vdp %p, dp %p, Attr %02x\n",
153 	    vdp, dp, dp->de_Attributes);
154 #endif
155 
156  restart:
157 	if (vpp != NULL)
158 		*vpp = NULL;
159 	/*
160 	 * If they are going after the . or .. entry in the root directory,
161 	 * they won't find it.  DOS filesystems don't have them in the root
162 	 * directory.  So, we fake it. deget() is in on this scam too.
163 	 */
164 	if ((vdp->v_vflag & VV_ROOT) && cnp->cn_nameptr[0] == '.' &&
165 	    (cnp->cn_namelen == 1 ||
166 		(cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
167 		isadir = ATTR_DIRECTORY;
168 		scn = MSDOSFSROOT;
169 #ifdef MSDOSFS_DEBUG
170 		printf("msdosfs_lookup(): looking for . or .. in root directory\n");
171 #endif
172 		cluster = MSDOSFSROOT;
173 		blkoff = MSDOSFSROOT_OFS;
174 		goto foundroot;
175 	}
176 
177 	switch (unix2dosfn((const u_char *)cnp->cn_nameptr, dosfilename,
178 	    cnp->cn_namelen, 0, pmp)) {
179 	case 0:
180 		return (EINVAL);
181 	case 1:
182 		break;
183 	case 2:
184 		wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
185 		    cnp->cn_namelen, pmp) + 1;
186 		break;
187 	case 3:
188 		olddos = 0;
189 		wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
190 		    cnp->cn_namelen, pmp) + 1;
191 		break;
192 	}
193 	if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME) {
194 		wincnt = 1;
195 		olddos = 1;
196 	}
197 	unlen = winLenFixup(cnp->cn_nameptr, cnp->cn_namelen);
198 
199 	/*
200 	 * Suppress search for slots unless creating
201 	 * file and at end of pathname, in which case
202 	 * we watch for a place to put the new file in
203 	 * case it doesn't already exist.
204 	 */
205 	slotcount = wincnt;
206 	if ((nameiop == CREATE || nameiop == RENAME) &&
207 	    (flags & ISLASTCN))
208 		slotcount = 0;
209 
210 #ifdef MSDOSFS_DEBUG
211 	printf("msdosfs_lookup(): dos version of filename %s, length %ld\n",
212 	    dosfilename, cnp->cn_namelen);
213 #endif
214 	/*
215 	 * Search the directory pointed at by vdp for the name pointed at
216 	 * by cnp->cn_nameptr.
217 	 */
218 	tdp = NULL;
219 	mbnambuf_init(&nb);
220 	/*
221 	 * The outer loop ranges over the clusters that make up the
222 	 * directory.  Note that the root directory is different from all
223 	 * other directories.  It has a fixed number of blocks that are not
224 	 * part of the pool of allocatable clusters.  So, we treat it a
225 	 * little differently. The root directory starts at "cluster" 0.
226 	 */
227 	diroff = 0;
228 	for (frcn = 0;; frcn++) {
229 		error = pcbmap(dp, frcn, &bn, &cluster, &blsize);
230 		if (error) {
231 			if (error == E2BIG)
232 				break;
233 			return (error);
234 		}
235 		error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
236 		if (error) {
237 			brelse(bp);
238 			return (error);
239 		}
240 		for (blkoff = 0; blkoff < blsize;
241 		     blkoff += sizeof(struct direntry),
242 		     diroff += sizeof(struct direntry)) {
243 			dep = (struct direntry *)(bp->b_data + blkoff);
244 			/*
245 			 * If the slot is empty and we are still looking
246 			 * for an empty then remember this one.  If the
247 			 * slot is not empty then check to see if it
248 			 * matches what we are looking for.  If the slot
249 			 * has never been filled with anything, then the
250 			 * remainder of the directory has never been used,
251 			 * so there is no point in searching it.
252 			 */
253 			if (dep->deName[0] == SLOT_EMPTY ||
254 			    dep->deName[0] == SLOT_DELETED) {
255 				/*
256 				 * Drop memory of previous long matches
257 				 */
258 				chksum = -1;
259 				mbnambuf_init(&nb);
260 
261 				if (slotcount < wincnt) {
262 					slotcount++;
263 					slotoffset = diroff;
264 				}
265 				if (dep->deName[0] == SLOT_EMPTY) {
266 					brelse(bp);
267 					goto notfound;
268 				}
269 			} else {
270 				/*
271 				 * If there wasn't enough space for our winentries,
272 				 * forget about the empty space
273 				 */
274 				if (slotcount < wincnt)
275 					slotcount = 0;
276 
277 				/*
278 				 * Check for Win95 long filename entry
279 				 */
280 				if (dep->deAttributes == ATTR_WIN95) {
281 					if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
282 						continue;
283 
284 					chksum = win2unixfn(&nb,
285 					    (struct winentry *)dep, chksum,
286 					    pmp);
287 					continue;
288 				}
289 
290 				chksum = winChkName(&nb,
291 				    (const u_char *)cnp->cn_nameptr, unlen,
292 				    chksum, pmp);
293 				if (chksum == -2) {
294 					chksum = -1;
295 					continue;
296 				}
297 
298 				/*
299 				 * Ignore volume labels (anywhere, not just
300 				 * the root directory).
301 				 */
302 				if (dep->deAttributes & ATTR_VOLUME) {
303 					chksum = -1;
304 					continue;
305 				}
306 
307 				/*
308 				 * Check for a checksum or name match
309 				 */
310 				chksum_ok = (chksum == winChksum(dep->deName));
311 				if (!chksum_ok
312 				    && (!olddos || bcmp(dosfilename, dep->deName, 11))) {
313 					chksum = -1;
314 					continue;
315 				}
316 #ifdef MSDOSFS_DEBUG
317 				printf("msdosfs_lookup(): match blkoff %d, diroff %d\n",
318 				    blkoff, diroff);
319 #endif
320 				/*
321 				 * Remember where this directory
322 				 * entry came from for whoever did
323 				 * this lookup.
324 				 */
325 				dp->de_fndoffset = diroff;
326 				if (chksum_ok && nameiop == RENAME) {
327 					/*
328 					 * Target had correct long name
329 					 * directory entries, reuse them
330 					 * as needed.
331 					 */
332 					dp->de_fndcnt = wincnt - 1;
333 				} else {
334 					/*
335 					 * Long name directory entries
336 					 * not present or corrupt, can only
337 					 * reuse dos directory entry.
338 					 */
339 					dp->de_fndcnt = 0;
340 				}
341 
342 				goto found;
343 			}
344 		}	/* for (blkoff = 0; .... */
345 		/*
346 		 * Release the buffer holding the directory cluster just
347 		 * searched.
348 		 */
349 		brelse(bp);
350 	}	/* for (frcn = 0; ; frcn++) */
351 
352 notfound:
353 	/*
354 	 * We hold no disk buffers at this point.
355 	 */
356 
357 	/*
358 	 * Fixup the slot description to point to the place where
359 	 * we might put the new DOS direntry (putting the Win95
360 	 * long name entries before that)
361 	 */
362 	if (!slotcount) {
363 		slotcount = 1;
364 		slotoffset = diroff;
365 	}
366 	if (wincnt > slotcount)
367 		slotoffset += sizeof(struct direntry) * (wincnt - slotcount);
368 
369 	/*
370 	 * If we get here we didn't find the entry we were looking for. But
371 	 * that's ok if we are creating or renaming and are at the end of
372 	 * the pathname and the directory hasn't been removed.
373 	 */
374 #ifdef MSDOSFS_DEBUG
375 	printf("msdosfs_lookup(): op %d, refcnt %ld\n",
376 	    nameiop, dp->de_refcnt);
377 	printf("               slotcount %d, slotoffset %d\n",
378 	       slotcount, slotoffset);
379 #endif
380 	if ((nameiop == CREATE || nameiop == RENAME) &&
381 	    (flags & ISLASTCN) && dp->de_refcnt != 0) {
382 		/*
383 		 * Access for write is interpreted as allowing
384 		 * creation of files in the directory.
385 		 */
386 		error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
387 		if (error)
388 			return (error);
389 		/*
390 		 * Return an indication of where the new directory
391 		 * entry should be put.
392 		 */
393 		dp->de_fndoffset = slotoffset;
394 		dp->de_fndcnt = wincnt - 1;
395 
396 		/*
397 		 * We return with the directory locked, so that
398 		 * the parameters we set up above will still be
399 		 * valid if we actually decide to do a direnter().
400 		 * We return ni_vp == NULL to indicate that the entry
401 		 * does not currently exist; we leave a pointer to
402 		 * the (locked) directory inode in ndp->ni_dvp.
403 		 * The pathname buffer is saved so that the name
404 		 * can be obtained later.
405 		 *
406 		 * NB - if the directory is unlocked, then this
407 		 * information cannot be used.
408 		 */
409 		cnp->cn_flags |= SAVENAME;
410 		return (EJUSTRETURN);
411 	}
412 #if 0
413 	/*
414 	 * Insert name into cache (as non-existent) if appropriate.
415 	 *
416 	 * XXX Negative caching is broken for msdosfs because the name
417 	 * cache doesn't understand peculiarities such as case insensitivity
418 	 * and 8.3 filenames.  Hence, it may not invalidate all negative
419 	 * entries if a file with this name is later created.
420 	 */
421 	if ((cnp->cn_flags & MAKEENTRY) != 0)
422 		cache_enter(vdp, *vpp, cnp);
423 #endif
424 	return (ENOENT);
425 
426 found:
427 	/*
428 	 * NOTE:  We still have the buffer with matched directory entry at
429 	 * this point.
430 	 */
431 	isadir = dep->deAttributes & ATTR_DIRECTORY;
432 	scn = getushort(dep->deStartCluster);
433 	if (FAT32(pmp)) {
434 		scn |= getushort(dep->deHighClust) << 16;
435 		if (scn == pmp->pm_rootdirblk) {
436 			/*
437 			 * There should actually be 0 here.
438 			 * Just ignore the error.
439 			 */
440 			scn = MSDOSFSROOT;
441 		}
442 	}
443 
444 	if (isadir) {
445 		cluster = scn;
446 		if (cluster == MSDOSFSROOT)
447 			blkoff = MSDOSFSROOT_OFS;
448 		else
449 			blkoff = 0;
450 	} else if (cluster == MSDOSFSROOT)
451 		blkoff = diroff;
452 
453 	/*
454 	 * Now release buf to allow deget to read the entry again.
455 	 * Reserving it here and giving it to deget could result
456 	 * in a deadlock.
457 	 */
458 	brelse(bp);
459 	bp = NULL;
460 
461 foundroot:
462 	/*
463 	 * If we entered at foundroot, then we are looking for the . or ..
464 	 * entry of the filesystems root directory.  isadir and scn were
465 	 * setup before jumping here.  And, bp is already null.
466 	 */
467 	if (FAT32(pmp) && scn == MSDOSFSROOT)
468 		scn = pmp->pm_rootdirblk;
469 
470 	if (dd_inum != NULL) {
471 		*dd_inum = (uint64_t)pmp->pm_bpcluster * scn + blkoff;
472 		return (0);
473 	}
474 
475 	/*
476 	 * If deleting, and at end of pathname, return
477 	 * parameters which can be used to remove file.
478 	 */
479 	if (nameiop == DELETE && (flags & ISLASTCN)) {
480 		/*
481 		 * Don't allow deleting the root.
482 		 */
483 		if (blkoff == MSDOSFSROOT_OFS)
484 			return (EBUSY);
485 
486 		/*
487 		 * Write access to directory required to delete files.
488 		 */
489 		error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
490 		if (error)
491 			return (error);
492 
493 		/*
494 		 * Return pointer to current entry in dp->i_offset.
495 		 * Save directory inode pointer in ndp->ni_dvp for dirremove().
496 		 */
497 		if (dp->de_StartCluster == scn && isadir) {	/* "." */
498 			VREF(vdp);
499 			*vpp = vdp;
500 			return (0);
501 		}
502 		error = deget(pmp, cluster, blkoff, &tdp);
503 		if (error)
504 			return (error);
505 		*vpp = DETOV(tdp);
506 		return (0);
507 	}
508 
509 	/*
510 	 * If rewriting (RENAME), return the inode and the
511 	 * information required to rewrite the present directory
512 	 * Must get inode of directory entry to verify it's a
513 	 * regular file, or empty directory.
514 	 */
515 	if (nameiop == RENAME && (flags & ISLASTCN)) {
516 		if (blkoff == MSDOSFSROOT_OFS)
517 			return (EBUSY);
518 
519 		error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
520 		if (error)
521 			return (error);
522 
523 		/*
524 		 * Careful about locking second inode.
525 		 * This can only occur if the target is ".".
526 		 */
527 		if (dp->de_StartCluster == scn && isadir)
528 			return (EISDIR);
529 
530 		if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
531 			return (error);
532 		*vpp = DETOV(tdp);
533 		cnp->cn_flags |= SAVENAME;
534 		return (0);
535 	}
536 
537 	/*
538 	 * Step through the translation in the name.  We do not `vput' the
539 	 * directory because we may need it again if a symbolic link
540 	 * is relative to the current directory.  Instead we save it
541 	 * unlocked as "pdp".  We must get the target inode before unlocking
542 	 * the directory to insure that the inode will not be removed
543 	 * before we get it.  We prevent deadlock by always fetching
544 	 * inodes from the root, moving down the directory tree. Thus
545 	 * when following backward pointers ".." we must unlock the
546 	 * parent directory before getting the requested directory.
547 	 */
548 	pdp = vdp;
549 	if (flags & ISDOTDOT) {
550 		dd_arg.cluster = cluster;
551 		dd_arg.blkoff = blkoff;
552 		error = vn_vget_ino_gen(vdp, msdosfs_deget_dotdot,
553 		    &dd_arg, cnp->cn_lkflags, vpp);
554 		if (error != 0) {
555 			*vpp = NULL;
556 			return (error);
557 		}
558 		/*
559 		 * Recheck that ".." still points to the inode we
560 		 * looked up before pdp lock was dropped.
561 		 */
562 		error = msdosfs_lookup_(pdp, NULL, cnp, &inode1);
563 		if (error) {
564 			vput(*vpp);
565 			*vpp = NULL;
566 			return (error);
567 		}
568 		if (VTODE(*vpp)->de_inode != inode1) {
569 			vput(*vpp);
570 			goto restart;
571 		}
572 	} else if (dp->de_StartCluster == scn && isadir) {
573 		VREF(vdp);	/* we want ourself, ie "." */
574 		*vpp = vdp;
575 	} else {
576 		if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
577 			return (error);
578 		*vpp = DETOV(tdp);
579 	}
580 
581 	/*
582 	 * Insert name into cache if appropriate.
583 	 */
584 	if (cnp->cn_flags & MAKEENTRY)
585 		cache_enter(vdp, *vpp, cnp);
586 	return (0);
587 }
588 
589 /*
590  * dep  - directory entry to copy into the directory
591  * ddep - directory to add to
592  * depp - return the address of the denode for the created directory entry
593  *	  if depp != 0
594  * cnp  - componentname needed for Win95 long filenames
595  */
596 int
597 createde(struct denode *dep, struct denode *ddep, struct denode **depp,
598     struct componentname *cnp)
599 {
600 	int error;
601 	u_long dirclust, diroffset;
602 	struct direntry *ndep;
603 	struct msdosfsmount *pmp = ddep->de_pmp;
604 	struct buf *bp;
605 	daddr_t bn;
606 	int blsize;
607 
608 #ifdef MSDOSFS_DEBUG
609 	printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
610 	    dep, ddep, depp, cnp);
611 #endif
612 
613 	/*
614 	 * If no space left in the directory then allocate another cluster
615 	 * and chain it onto the end of the file.  There is one exception
616 	 * to this.  That is, if the root directory has no more space it
617 	 * can NOT be expanded.  extendfile() checks for and fails attempts
618 	 * to extend the root directory.  We just return an error in that
619 	 * case.
620 	 */
621 	if (ddep->de_fndoffset >= ddep->de_FileSize) {
622 		diroffset = ddep->de_fndoffset + sizeof(struct direntry)
623 		    - ddep->de_FileSize;
624 		dirclust = de_clcount(pmp, diroffset);
625 		error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR);
626 		if (error) {
627 			(void)detrunc(ddep, ddep->de_FileSize, 0, NOCRED);
628 			return error;
629 		}
630 
631 		/*
632 		 * Update the size of the directory
633 		 */
634 		ddep->de_FileSize += de_cn2off(pmp, dirclust);
635 	}
636 
637 	/*
638 	 * We just read in the cluster with space.  Copy the new directory
639 	 * entry in.  Then write it to disk. NOTE:  DOS directories
640 	 * do not get smaller as clusters are emptied.
641 	 */
642 	error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
643 		       &bn, &dirclust, &blsize);
644 	if (error)
645 		return error;
646 	diroffset = ddep->de_fndoffset;
647 	if (dirclust != MSDOSFSROOT)
648 		diroffset &= pmp->pm_crbomask;
649 	if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) != 0) {
650 		brelse(bp);
651 		return error;
652 	}
653 	ndep = bptoep(pmp, bp, ddep->de_fndoffset);
654 
655 	DE_EXTERNALIZE(ndep, dep);
656 
657 	/*
658 	 * Now write the Win95 long name
659 	 */
660 	if (ddep->de_fndcnt > 0) {
661 		uint8_t chksum = winChksum(ndep->deName);
662 		const u_char *un = (const u_char *)cnp->cn_nameptr;
663 		int unlen = cnp->cn_namelen;
664 		int cnt = 1;
665 
666 		while (--ddep->de_fndcnt >= 0) {
667 			if (!(ddep->de_fndoffset & pmp->pm_crbomask)) {
668 				if (DOINGASYNC(DETOV(ddep)))
669 					bdwrite(bp);
670 				else if ((error = bwrite(bp)) != 0)
671 					return error;
672 
673 				ddep->de_fndoffset -= sizeof(struct direntry);
674 				error = pcbmap(ddep,
675 					       de_cluster(pmp,
676 							  ddep->de_fndoffset),
677 					       &bn, 0, &blsize);
678 				if (error)
679 					return error;
680 
681 				error = bread(pmp->pm_devvp, bn, blsize,
682 					      NOCRED, &bp);
683 				if (error) {
684 					brelse(bp);
685 					return error;
686 				}
687 				ndep = bptoep(pmp, bp, ddep->de_fndoffset);
688 			} else {
689 				ndep--;
690 				ddep->de_fndoffset -= sizeof(struct direntry);
691 			}
692 			if (!unix2winfn(un, unlen, (struct winentry *)ndep,
693 					cnt++, chksum, pmp))
694 				break;
695 		}
696 	}
697 
698 	if (DOINGASYNC(DETOV(ddep)))
699 		bdwrite(bp);
700 	else if ((error = bwrite(bp)) != 0)
701 		return error;
702 
703 	/*
704 	 * If they want us to return with the denode gotten.
705 	 */
706 	if (depp) {
707 		if (dep->de_Attributes & ATTR_DIRECTORY) {
708 			dirclust = dep->de_StartCluster;
709 			if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
710 				dirclust = MSDOSFSROOT;
711 			if (dirclust == MSDOSFSROOT)
712 				diroffset = MSDOSFSROOT_OFS;
713 			else
714 				diroffset = 0;
715 		}
716 		return deget(pmp, dirclust, diroffset, depp);
717 	}
718 
719 	return 0;
720 }
721 
722 /*
723  * Be sure a directory is empty except for "." and "..". Return 1 if empty,
724  * return 0 if not empty or error.
725  */
726 int
727 dosdirempty(struct denode *dep)
728 {
729 	int blsize;
730 	int error;
731 	u_long cn;
732 	daddr_t bn;
733 	struct buf *bp;
734 	struct msdosfsmount *pmp = dep->de_pmp;
735 	struct direntry *dentp;
736 
737 	/*
738 	 * Since the filesize field in directory entries for a directory is
739 	 * zero, we just have to feel our way through the directory until
740 	 * we hit end of file.
741 	 */
742 	for (cn = 0;; cn++) {
743 		if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
744 			if (error == E2BIG)
745 				return (1);	/* it's empty */
746 			return (0);
747 		}
748 		error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
749 		if (error) {
750 			brelse(bp);
751 			return (0);
752 		}
753 		for (dentp = (struct direntry *)bp->b_data;
754 		     (char *)dentp < bp->b_data + blsize;
755 		     dentp++) {
756 			if (dentp->deName[0] != SLOT_DELETED &&
757 			    (dentp->deAttributes & ATTR_VOLUME) == 0) {
758 				/*
759 				 * In dos directories an entry whose name
760 				 * starts with SLOT_EMPTY (0) starts the
761 				 * beginning of the unused part of the
762 				 * directory, so we can just return that it
763 				 * is empty.
764 				 */
765 				if (dentp->deName[0] == SLOT_EMPTY) {
766 					brelse(bp);
767 					return (1);
768 				}
769 				/*
770 				 * Any names other than "." and ".." in a
771 				 * directory mean it is not empty.
772 				 */
773 				if (bcmp(dentp->deName, ".          ", 11) &&
774 				    bcmp(dentp->deName, "..         ", 11)) {
775 					brelse(bp);
776 #ifdef MSDOSFS_DEBUG
777 					printf("dosdirempty(): entry found %02x, %02x\n",
778 					    dentp->deName[0], dentp->deName[1]);
779 #endif
780 					return (0);	/* not empty */
781 				}
782 			}
783 		}
784 		brelse(bp);
785 	}
786 	/* NOTREACHED */
787 }
788 
789 /*
790  * Check to see if the directory described by target is in some
791  * subdirectory of source.  This prevents something like the following from
792  * succeeding and leaving a bunch or files and directories orphaned. mv
793  * /a/b/c /a/b/c/d/e/f Where c and f are directories.
794  *
795  * source - the inode for /a/b/c
796  * target - the inode for /a/b/c/d/e/f
797  *
798  * Returns 0 if target is NOT a subdirectory of source.
799  * Otherwise returns a non-zero error number.
800  * The target inode is always unlocked on return.
801  */
802 int
803 doscheckpath(struct denode *source, struct denode *target)
804 {
805 	daddr_t scn;
806 	struct msdosfsmount *pmp;
807 	struct direntry *ep;
808 	struct denode *dep;
809 	struct buf *bp = NULL;
810 	int error = 0;
811 
812 	dep = target;
813 	if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
814 	    (source->de_Attributes & ATTR_DIRECTORY) == 0) {
815 		error = ENOTDIR;
816 		goto out;
817 	}
818 	if (dep->de_StartCluster == source->de_StartCluster) {
819 		error = EEXIST;
820 		goto out;
821 	}
822 	if (dep->de_StartCluster == MSDOSFSROOT)
823 		goto out;
824 	pmp = dep->de_pmp;
825 #ifdef	DIAGNOSTIC
826 	if (pmp != source->de_pmp)
827 		panic("doscheckpath: source and target on different filesystems");
828 #endif
829 	if (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)
830 		goto out;
831 
832 	for (;;) {
833 		if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
834 			error = ENOTDIR;
835 			break;
836 		}
837 		scn = dep->de_StartCluster;
838 		error = bread(pmp->pm_devvp, cntobn(pmp, scn),
839 			      pmp->pm_bpcluster, NOCRED, &bp);
840 		if (error)
841 			break;
842 
843 		ep = (struct direntry *) bp->b_data + 1;
844 		if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
845 		    bcmp(ep->deName, "..         ", 11) != 0) {
846 			error = ENOTDIR;
847 			break;
848 		}
849 		scn = getushort(ep->deStartCluster);
850 		if (FAT32(pmp))
851 			scn |= getushort(ep->deHighClust) << 16;
852 
853 		if (scn == source->de_StartCluster) {
854 			error = EINVAL;
855 			break;
856 		}
857 		if (scn == MSDOSFSROOT)
858 			break;
859 		if (FAT32(pmp) && scn == pmp->pm_rootdirblk) {
860 			/*
861 			 * scn should be 0 in this case,
862 			 * but we silently ignore the error.
863 			 */
864 			break;
865 		}
866 
867 		vput(DETOV(dep));
868 		brelse(bp);
869 		bp = NULL;
870 		/* NOTE: deget() clears dep on error */
871 		if ((error = deget(pmp, scn, 0, &dep)) != 0)
872 			break;
873 	}
874 out:;
875 	if (bp)
876 		brelse(bp);
877 #ifdef MSDOSFS_DEBUG
878 	if (error == ENOTDIR)
879 		printf("doscheckpath(): .. not a directory?\n");
880 #endif
881 	if (dep != NULL)
882 		vput(DETOV(dep));
883 	return (error);
884 }
885 
886 /*
887  * Read in the disk block containing the directory entry (dirclu, dirofs)
888  * and return the address of the buf header, and the address of the
889  * directory entry within the block.
890  */
891 int
892 readep(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset,
893     struct buf **bpp, struct direntry **epp)
894 {
895 	int error;
896 	daddr_t bn;
897 	int blsize;
898 
899 	blsize = pmp->pm_bpcluster;
900 	if (dirclust == MSDOSFSROOT
901 	    && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
902 		blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
903 	bn = detobn(pmp, dirclust, diroffset);
904 	if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, bpp)) != 0) {
905 		brelse(*bpp);
906 		*bpp = NULL;
907 		return (error);
908 	}
909 	if (epp)
910 		*epp = bptoep(pmp, *bpp, diroffset);
911 	return (0);
912 }
913 
914 /*
915  * Read in the disk block containing the directory entry dep came from and
916  * return the address of the buf header, and the address of the directory
917  * entry within the block.
918  */
919 int
920 readde(struct denode *dep, struct buf **bpp, struct direntry **epp)
921 {
922 
923 	return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
924 	    bpp, epp));
925 }
926 
927 /*
928  * Remove a directory entry. At this point the file represented by the
929  * directory entry to be removed is still full length until no one has it
930  * open.  When the file no longer being used msdosfs_inactive() is called
931  * and will truncate the file to 0 length.  When the vnode containing the
932  * denode is needed for some other purpose by VFS it will call
933  * msdosfs_reclaim() which will remove the denode from the denode cache.
934  *
935  * pdep	directory where the entry is removed
936  * dep	file to be removed
937  */
938 int
939 removede(struct denode *pdep, struct denode *dep)
940 {
941 	int error;
942 	struct direntry *ep;
943 	struct buf *bp;
944 	daddr_t bn;
945 	int blsize;
946 	struct msdosfsmount *pmp = pdep->de_pmp;
947 	u_long offset = pdep->de_fndoffset;
948 
949 #ifdef MSDOSFS_DEBUG
950 	printf("removede(): filename %s, dep %p, offset %08lx\n",
951 	    dep->de_Name, dep, offset);
952 #endif
953 
954 	dep->de_refcnt--;
955 	offset += sizeof(struct direntry);
956 	do {
957 		offset -= sizeof(struct direntry);
958 		error = pcbmap(pdep, de_cluster(pmp, offset), &bn, 0, &blsize);
959 		if (error)
960 			return error;
961 		error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
962 		if (error) {
963 			brelse(bp);
964 			return error;
965 		}
966 		ep = bptoep(pmp, bp, offset);
967 		/*
968 		 * Check whether, if we came here the second time, i.e.
969 		 * when underflowing into the previous block, the last
970 		 * entry in this block is a longfilename entry, too.
971 		 */
972 		if (ep->deAttributes != ATTR_WIN95
973 		    && offset != pdep->de_fndoffset) {
974 			brelse(bp);
975 			break;
976 		}
977 		offset += sizeof(struct direntry);
978 		while (1) {
979 			/*
980 			 * We are a bit aggressive here in that we delete any Win95
981 			 * entries preceding this entry, not just the ones we "own".
982 			 * Since these presumably aren't valid anyway,
983 			 * there should be no harm.
984 			 */
985 			offset -= sizeof(struct direntry);
986 			ep--->deName[0] = SLOT_DELETED;
987 			if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
988 			    || !(offset & pmp->pm_crbomask)
989 			    || ep->deAttributes != ATTR_WIN95)
990 				break;
991 		}
992 		if (DOINGASYNC(DETOV(pdep)))
993 			bdwrite(bp);
994 		else if ((error = bwrite(bp)) != 0)
995 			return error;
996 	} while (!(pmp->pm_flags & MSDOSFSMNT_NOWIN95)
997 	    && !(offset & pmp->pm_crbomask)
998 	    && offset);
999 	return 0;
1000 }
1001 
1002 /*
1003  * Create a unique DOS name in dvp
1004  */
1005 int
1006 uniqdosname(struct denode *dep, struct componentname *cnp, u_char *cp)
1007 {
1008 	struct msdosfsmount *pmp = dep->de_pmp;
1009 	struct direntry *dentp;
1010 	int gen;
1011 	int blsize;
1012 	u_long cn;
1013 	daddr_t bn;
1014 	struct buf *bp;
1015 	int error;
1016 
1017 	if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
1018 		return (unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
1019 		    cnp->cn_namelen, 0, pmp) ? 0 : EINVAL);
1020 
1021 	for (gen = 1;; gen++) {
1022 		/*
1023 		 * Generate DOS name with generation number
1024 		 */
1025 		if (!unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
1026 		    cnp->cn_namelen, gen, pmp))
1027 			return gen == 1 ? EINVAL : EEXIST;
1028 
1029 		/*
1030 		 * Now look for a dir entry with this exact name
1031 		 */
1032 		for (cn = error = 0; !error; cn++) {
1033 			if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
1034 				if (error == E2BIG)	/* EOF reached and not found */
1035 					return 0;
1036 				return error;
1037 			}
1038 			error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
1039 			if (error) {
1040 				brelse(bp);
1041 				return error;
1042 			}
1043 			for (dentp = (struct direntry *)bp->b_data;
1044 			     (char *)dentp < bp->b_data + blsize;
1045 			     dentp++) {
1046 				if (dentp->deName[0] == SLOT_EMPTY) {
1047 					/*
1048 					 * Last used entry and not found
1049 					 */
1050 					brelse(bp);
1051 					return 0;
1052 				}
1053 				/*
1054 				 * Ignore volume labels and Win95 entries
1055 				 */
1056 				if (dentp->deAttributes & ATTR_VOLUME)
1057 					continue;
1058 				if (!bcmp(dentp->deName, cp, 11)) {
1059 					error = EEXIST;
1060 					break;
1061 				}
1062 			}
1063 			brelse(bp);
1064 		}
1065 	}
1066 }
1067