xref: /freebsd/sbin/umount/umount.c (revision 77a0943ded95b9e6438f7db70c4a28e4d93946d4)
1 /*-
2  * Copyright (c) 1980, 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 static const char copyright[] =
36 "@(#) Copyright (c) 1980, 1989, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 #if 0
42 static char sccsid[] = "@(#)umount.c	8.8 (Berkeley) 5/8/95";
43 #endif
44 static const char rcsid[] =
45   "$FreeBSD$";
46 #endif /* not lint */
47 
48 #include <sys/param.h>
49 #include <sys/mount.h>
50 
51 #include <netdb.h>
52 #include <rpc/rpc.h>
53 #include <nfs/rpcv2.h>
54 
55 #include <err.h>
56 #include <fstab.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <unistd.h>
61 
62 #include "mounttab.h"
63 
64 #define ISDOT(x)	((x)[0] == '.' && (x)[1] == '\0')
65 #define ISDOTDOT(x)	((x)[0] == '.' && (x)[1] == '.' && (x)[2] == '\0')
66 
67 typedef enum { MNTON, MNTFROM, NOTHING } mntwhat;
68 typedef enum { MARK, UNMARK, NAME, COUNT, FREE } dowhat;
69 
70 struct	mtablist *mtabhead;
71 int	fflag, vflag;
72 char   *nfshost;
73 
74 void	 checkmntlist (char *, char **, char **, char **);
75 int	 checkvfsname (const char *, char **);
76 char	*getmntname (const char *, const char *,
77 	 mntwhat, char **, dowhat);
78 char 	*getrealname(char *, char *resolved_path);
79 char   **makevfslist (const char *);
80 size_t	 mntinfo (struct statfs **);
81 int	 namematch (struct hostent *);
82 int	 umountall (char **);
83 int	 umountfs (char *, char **);
84 void	 usage (void);
85 int	 xdr_dir (XDR *, char *);
86 
87 int
88 main(int argc, char *argv[])
89 {
90 	int all, errs, ch, mntsize;
91 	char **typelist = NULL, *mntonname, *mntfromname;
92 	char *type, *mntfromnamerev, *mntonnamerev;
93 	struct statfs *mntbuf;
94 
95 	/* Start disks transferring immediately. */
96 	sync();
97 
98 	all = errs = 0;
99 	while ((ch = getopt(argc, argv, "Aafh:t:v")) != -1)
100 		switch (ch) {
101 		case 'A':
102 			all = 2;
103 			break;
104 		case 'a':
105 			all = 1;
106 			break;
107 		case 'f':
108 			fflag = MNT_FORCE;
109 			break;
110 		case 'h':	/* -h implies -A. */
111 			all = 2;
112 			nfshost = optarg;
113 			break;
114 		case 't':
115 			if (typelist != NULL)
116 				err(1, "only one -t option may be specified");
117 			typelist = makevfslist(optarg);
118 			break;
119 		case 'v':
120 			vflag = 1;
121 			break;
122 		default:
123 			usage();
124 			/* NOTREACHED */
125 		}
126 	argc -= optind;
127 	argv += optind;
128 
129 	if ((argc == 0 && !all) || (argc != 0 && all))
130 		usage();
131 
132 	/* -h implies "-t nfs" if no -t flag. */
133 	if ((nfshost != NULL) && (typelist == NULL))
134 		typelist = makevfslist("nfs");
135 
136 	switch (all) {
137 	case 2:
138 		if ((mntsize = mntinfo(&mntbuf)) <= 0)
139 			break;
140 		/*
141 		 * We unmount the nfs-mounts in the reverse order
142 		 * that they were mounted.
143 		 */
144 		for (errs = 0, mntsize--; mntsize > 0; mntsize--) {
145 			if (checkvfsname(mntbuf[mntsize].f_fstypename,
146 			    typelist))
147 				continue;
148 			/*
149 			 * Check if a mountpoint is laid over by another mount.
150 			 * A warning will be printed to stderr if this is
151 			 * the case. The laid over mount remains unmounted.
152 			 */
153 			mntonname = mntbuf[mntsize].f_mntonname;
154 			mntfromname = mntbuf[mntsize].f_mntfromname;
155 			mntonnamerev = getmntname(getmntname(mntonname,
156 			    NULL, MNTFROM, &type, NAME), NULL,
157 			    MNTON, &type, NAME);
158 
159 			mntfromnamerev = getmntname(mntonnamerev,
160 			    NULL, MNTFROM, &type, NAME);
161 
162 			if (strcmp(mntonnamerev, mntonname) == 0 &&
163 			    strcmp(mntfromnamerev, mntfromname ) != 0)
164 				warnx("cannot umount %s, %s\n        "
165 				    "is mounted there, umount it first",
166 				    mntonname, mntfromnamerev);
167 
168 			if (umountfs(mntbuf[mntsize].f_mntonname,
169 			    typelist) != 0)
170 				errs = 1;
171 		}
172 		free(mntbuf);
173 		break;
174 	case 1:
175 		if (setfsent() == 0)
176 			err(1, "%s", _PATH_FSTAB);
177 		errs = umountall(typelist);
178 		break;
179 	case 0:
180 		for (errs = 0; *argv != NULL; ++argv)
181 			if (umountfs(*argv, typelist) != 0)
182 				errs = 1;
183 		break;
184 	}
185 	(void)getmntname(NULL, NULL, NOTHING, NULL, FREE);
186 	exit(errs);
187 }
188 
189 int
190 umountall(char **typelist)
191 {
192 	struct vfsconf vfc;
193 	struct fstab *fs;
194 	int rval;
195 	char *cp;
196 	static int firstcall = 1;
197 
198 	if ((fs = getfsent()) != NULL)
199 		firstcall = 0;
200 	else if (firstcall)
201 		errx(1, "fstab reading failure");
202 	else
203 		return (0);
204 	do {
205 		/* Ignore the root. */
206 		if (strcmp(fs->fs_file, "/") == 0)
207 			continue;
208 		/*
209 		 * !!!
210 		 * Historic practice: ignore unknown FSTAB_* fields.
211 		 */
212 		if (strcmp(fs->fs_type, FSTAB_RW) &&
213 		    strcmp(fs->fs_type, FSTAB_RO) &&
214 		    strcmp(fs->fs_type, FSTAB_RQ))
215 			continue;
216 		/* Ignore unknown file system types. */
217 		if (getvfsbyname(fs->fs_vfstype, &vfc) == -1)
218 			continue;
219 		if (checkvfsname(fs->fs_vfstype, typelist))
220 			continue;
221 
222 		/*
223 		 * We want to unmount the file systems in the reverse order
224 		 * that they were mounted.  So, we save off the file name
225 		 * in some allocated memory, and then call recursively.
226 		 */
227 		if ((cp = malloc((size_t)strlen(fs->fs_file) + 1)) == NULL)
228 			err(1, "malloc failed");
229 		(void)strcpy(cp, fs->fs_file);
230 		rval = umountall(typelist);
231 		rval = umountfs(cp, typelist) || rval;
232 		free(cp);
233 		return (rval);
234 	} while ((fs = getfsent()) != NULL);
235 	return (0);
236 }
237 
238 int
239 umountfs(char *name, char **typelist)
240 {
241 	enum clnt_stat clnt_stat;
242 	struct hostent *hp;
243 	struct mtablist *mtab;
244 	struct sockaddr_in saddr;
245 	struct timeval pertry, try;
246 	CLIENT *clp;
247 	size_t len;
248 	int so, speclen, do_rpc;
249 	char *mntonname, *mntfromname;
250 	char *mntfromnamerev;
251 	char *nfsdirname, *orignfsdirname;
252 	char *resolved, realname[MAXPATHLEN];
253 	char *type, *delimp, *hostp, *origname;
254 
255 	len = 0;
256 	mtab = NULL;
257 	mntfromname = mntonname = delimp = hostp = orignfsdirname = NULL;
258 
259 	/*
260 	 * 1. Check if the name exists in the mounttable.
261 	 */
262 	(void)checkmntlist(name, &mntfromname, &mntonname, &type);
263 	/*
264 	 * 2. Remove trailing slashes if there are any. After that
265 	 * we look up the name in the mounttable again.
266 	 */
267 	if (mntfromname == NULL && mntonname == NULL) {
268 		speclen = strlen(name);
269 		for (speclen = strlen(name);
270 		    speclen > 1 && name[speclen - 1] == '/';
271 		    speclen--)
272 			name[speclen - 1] = '\0';
273 		(void)checkmntlist(name, &mntfromname, &mntonname, &type);
274 		resolved = name;
275 		/* Save off original name in origname */
276 		if ((origname = strdup(name)) == NULL)
277 			err(1, "strdup");
278 		/*
279 		 * 3. Check if the deprecated nfs-syntax with an '@'
280 		 * has been used and translate it to the ':' syntax.
281 		 * Look up the name in the mounttable again.
282 		 */
283 		if (mntfromname == NULL && mntonname == NULL) {
284 			if ((delimp = strrchr(name, '@')) != NULL) {
285 				hostp = delimp + 1;
286 				if (*hostp != '\0') {
287 					/*
288 					 * Make both '@' and ':'
289 					 * notations equal
290 					 */
291 					char *host = strdup(hostp);
292 					len = strlen(hostp);
293 					if (host == NULL)
294 						err(1, "strdup");
295 					memmove(name + len + 1, name,
296 					    (size_t)(delimp - name));
297 					name[len] = ':';
298 					memmove(name, host, len);
299 					free(host);
300 				}
301 				for (speclen = strlen(name);
302 				    speclen > 1 && name[speclen - 1] == '/';
303 				    speclen--)
304 					name[speclen - 1] = '\0';
305 				name[len + speclen + 1] = '\0';
306 				(void)checkmntlist(name, &mntfromname,
307 				    &mntonname, &type);
308 				resolved = name;
309 			}
310 			/*
311 			 * 4. Check if a relative mountpoint has been
312 			 * specified. This should happen as last check,
313 			 * the order is important. To prevent possible
314 			 * nfs-hangs, we just call realpath(3) on the
315 			 * basedir of mountpoint and add the dirname again.
316 			 * Check the name in mounttable one last time.
317 			 */
318 			if (mntfromname == NULL && mntonname == NULL) {
319 				(void)strcpy(name, origname);
320 				if ((getrealname(name, realname)) != NULL) {
321 					(void)checkmntlist(realname,
322 					    &mntfromname, &mntonname, &type);
323 					resolved = realname;
324 				}
325 				/*
326 				 * All tests failed, return to main()
327 				 */
328 				if (mntfromname == NULL && mntonname == NULL) {
329 					(void)strcpy(name, origname);
330 					warnx("%s: not currently mounted",
331 					    origname);
332 					free(origname);
333 					return (1);
334 				}
335 			}
336 		}
337 		free(origname);
338 	} else
339 		resolved = name;
340 
341 	if (checkvfsname(type, typelist))
342 		return (1);
343 
344 	hp = NULL;
345 	nfsdirname = NULL;
346 	if (!strcmp(type, "nfs")) {
347 		if ((nfsdirname = strdup(mntfromname)) == NULL)
348 			err(1, "strdup");
349 		orignfsdirname = nfsdirname;
350 		if ((delimp = strchr(nfsdirname, ':')) != NULL) {
351 			*delimp = '\0';
352 			hostp = nfsdirname;
353 			if ((hp = gethostbyname(hostp)) == NULL) {
354 				warnx("can't get net id for host");
355 			}
356 			nfsdirname = delimp + 1;
357 		}
358 	}
359 	/*
360 	 * Check if the reverse entrys of the mounttable are really the
361 	 * same as the normal ones.
362 	 */
363 	if ((mntfromnamerev = strdup(getmntname(getmntname(mntfromname,
364 	    NULL, MNTON, &type, NAME), NULL, MNTFROM, &type, NAME))) == NULL)
365 		err(1, "strdup");
366 	/*
367 	 * Mark the uppermost mount as unmounted.
368 	 */
369 	(void)getmntname(mntfromname, mntonname, NOTHING, &type, MARK);
370 	/*
371 	 * If several equal mounts are in the mounttable, check the order
372 	 * and warn the user if necessary.
373 	 */
374 	if (strcmp(mntfromnamerev, mntfromname ) != 0 &&
375 	    strcmp(resolved, mntonname) != 0) {
376 		warnx("cannot umount %s, %s\n        "
377 		    "is mounted there, umount it first",
378 		    mntonname, mntfromnamerev);
379 
380 		/* call getmntname again to set mntcheck[i] to 0 */
381 		(void)getmntname(mntfromname, mntonname,
382 		    NOTHING, &type, UNMARK);
383 		return (1);
384 	}
385 	free(mntfromnamerev);
386 	/*
387 	 * Check if we have to start the rpc-call later.
388 	 * If there are still identical nfs-names mounted,
389 	 * we skip the rpc-call. Obviously this has to
390 	 * happen before unmount(2), but it should happen
391 	 * after the previous namecheck.
392 	 */
393 	if (strcmp(type, "nfs") == 0 && getmntname(mntfromname, NULL, NOTHING,
394 	    &type, COUNT) != NULL)
395 		do_rpc = 1;
396 	else
397 		do_rpc = 0;
398 	if (!namematch(hp))
399 		return (1);
400 	if (unmount(mntonname, fflag) != 0 ) {
401 		warn("unmount of %s failed", mntonname);
402 		return (1);
403 	}
404 	if (vflag)
405 		(void)printf("%s: unmount from %s\n", mntfromname, mntonname);
406 	/*
407 	 * Report to mountd-server which nfsname
408 	 * has been unmounted.
409 	 */
410 	if (hp != NULL && !(fflag & MNT_FORCE) && do_rpc) {
411 		memset(&saddr, 0, sizeof(saddr));
412 		saddr.sin_family = AF_INET;
413 		saddr.sin_port = 0;
414 		memmove(&saddr.sin_addr, hp->h_addr,
415 		    MIN(hp->h_length, sizeof(saddr.sin_addr)));
416 		pertry.tv_sec = 3;
417 		pertry.tv_usec = 0;
418 		so = RPC_ANYSOCK;
419 		if ((clp = clntudp_create(&saddr,
420 		    RPCPROG_MNT, RPCMNT_VER1, pertry, &so)) == NULL) {
421 			clnt_pcreateerror("Cannot MNT PRC");
422 			return (1);
423 		}
424 		clp->cl_auth = authunix_create_default();
425 		try.tv_sec = 20;
426 		try.tv_usec = 0;
427 		clnt_stat = clnt_call(clp, RPCMNT_UMOUNT, xdr_dir,
428 		    nfsdirname, xdr_void, (caddr_t)0, try);
429 		if (clnt_stat != RPC_SUCCESS) {
430 			clnt_perror(clp, "Bad MNT RPC");
431 			return (1);
432 		}
433 		/*
434 		 * Remove the unmounted entry from /var/db/mounttab.
435 		 */
436 		if (read_mtab(mtab)) {
437 			mtab = mtabhead;
438 			clean_mtab(hostp, nfsdirname);
439 			if(!write_mtab())
440 				warnx("cannot remove entry %s:%s",
441 				    hostp, nfsdirname);
442 			free_mtab();
443 		}
444 		free(orignfsdirname);
445 		auth_destroy(clp->cl_auth);
446 		clnt_destroy(clp);
447 	}
448 	return (0);
449 }
450 
451 char *
452 getmntname(const char *fromname, const char *onname,
453     mntwhat what, char **type, dowhat mark)
454 {
455 	static struct statfs *mntbuf;
456 	static size_t mntsize = 0;
457 	static char *mntcheck = NULL;
458 	static char *mntcount = NULL;
459 	int i, count;
460 
461 	if (mntsize <= 0) {
462 		if ((mntsize = mntinfo(&mntbuf)) <= 0)
463 			return (NULL);
464 	}
465 	if (mntcheck == NULL) {
466 		if ((mntcheck = calloc(mntsize + 1, sizeof(int))) == NULL ||
467 		    (mntcount = calloc(mntsize + 1, sizeof(int))) == NULL)
468 			err(1, "calloc");
469 	}
470 	/*
471 	 * We want to get the file systems in the reverse order
472 	 * that they were mounted. Mounted and unmounted filesystems
473 	 * are marked or unmarked in a table called 'mntcheck'.
474 	 * Unmount(const char *dir, int flags) does only take the
475 	 * mountpoint as argument, not the destination. If we don't pay
476 	 * attention to the order, it can happen that a overlaying
477 	 * filesystem get's unmounted instead of the one the user
478 	 * has choosen.
479 	 */
480 	switch (mark) {
481 	case NAME:
482 		/* Return only the specific name */
483 		for (i = mntsize - 1; i >= 0; i--) {
484 			if (fromname != NULL && what == MNTON &&
485 			    !strcmp(mntbuf[i].f_mntfromname, fromname) &&
486 			    mntcheck[i] != 1) {
487 				if (type)
488 					*type = mntbuf[i].f_fstypename;
489 				return (mntbuf[i].f_mntonname);
490 			}
491 			if (fromname != NULL && what == MNTFROM &&
492 			    !strcmp(mntbuf[i].f_mntonname, fromname) &&
493 			    mntcheck[i] != 1) {
494 				if (type)
495 					*type = mntbuf[i].f_fstypename;
496 				return (mntbuf[i].f_mntfromname);
497 			}
498 		}
499 		return (NULL);
500 	case MARK:
501 		/* Mark current mount with '1' and return name */
502 		for (i = mntsize - 1; i >= 0; i--) {
503 			if (mntcheck[i] == 0 &&
504 			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
505 			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
506 				mntcheck[i] = 1;
507 				return (mntbuf[i].f_mntonname);
508 			}
509 		}
510 		return (NULL);
511 	case UNMARK:
512 		/* Unmark current mount with '0' and return name */
513 		for (i = 0; i < mntsize; i++) {
514 			if (mntcheck[i] == 1 &&
515 			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
516 			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
517 				mntcheck[i] = 0;
518 				return (mntbuf[i].f_mntonname);
519 			}
520 		}
521 		return (NULL);
522 	case COUNT:
523 		/* Count the equal mntfromnames */
524 		count = 0;
525 		for (i = mntsize - 1; i >= 0; i--) {
526 			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)
527 				count++;
528 		}
529 		/* Mark the already unmounted mounts and return
530 		 * mntfromname if count <= 1. Else return NULL.
531 		 */
532 		for (i = mntsize - 1; i >= 0; i--) {
533 			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0) {
534 				if (mntcount[i] == 1)
535 					count--;
536 				else {
537 					mntcount[i] = 1;
538 					break;
539 				}
540 			}
541 		}
542 		if (count <= 1)
543 			return (mntbuf[i].f_mntonname);
544 		else
545 			return (NULL);
546 	case FREE:
547 		free(mntbuf);
548 		free(mntcheck);
549 		free(mntcount);
550 		return (NULL);
551 	default:
552 		return (NULL);
553 	}
554 }
555 
556 int
557 namematch(struct hostent *hp)
558 {
559 	char *cp, **np;
560 
561 	if ((hp == NULL) || (nfshost == NULL))
562 		return (1);
563 
564 	if (strcasecmp(nfshost, hp->h_name) == 0)
565 		return (1);
566 
567 	if ((cp = strchr(hp->h_name, '.')) != NULL) {
568 		*cp = '\0';
569 		if (strcasecmp(nfshost, hp->h_name) == 0)
570 			return (1);
571 	}
572 	for (np = hp->h_aliases; *np; np++) {
573 		if (strcasecmp(nfshost, *np) == 0)
574 			return (1);
575 		if ((cp = strchr(*np, '.')) != NULL) {
576 			*cp = '\0';
577 			if (strcasecmp(nfshost, *np) == 0)
578 				return (1);
579 		}
580 	}
581 	return (0);
582 }
583 
584 void
585 checkmntlist(char *name, char **fromname, char **onname, char **type)
586 {
587 
588 	*fromname = getmntname(name, NULL, MNTFROM, type, NAME);
589 	if (*fromname == NULL) {
590 		*onname = getmntname(name, NULL, MNTON, type, NAME);
591 		if (*onname != NULL)
592 			*fromname = name;
593 	} else
594 		*onname = name;
595 }
596 
597 size_t
598 mntinfo(struct statfs **mntbuf)
599 {
600 	static struct statfs *origbuf;
601 	size_t bufsize;
602 	int mntsize;
603 
604 	mntsize = getfsstat(NULL, 0, MNT_NOWAIT);
605 	if (mntsize <= 0)
606 		return (0);
607 	bufsize = (mntsize + 1) * sizeof(struct statfs);
608 	if ((origbuf = malloc(bufsize)) == NULL)
609 		err(1, "malloc");
610 	mntsize = getfsstat(origbuf, (long)bufsize, MNT_NOWAIT);
611 	*mntbuf = origbuf;
612 	return (mntsize);
613 }
614 
615 char *
616 getrealname(char *name, char *realname)
617 {
618 	char *dirname;
619 	int havedir;
620 	size_t baselen;
621 	size_t dirlen;
622 
623 	dirname = '\0';
624 	havedir = 0;
625 	if (*name == '/') {
626 		if (ISDOT(name + 1) || ISDOTDOT(name + 1))
627 			strcpy(realname, "/");
628 		else {
629 			if ((dirname = strrchr(name + 1, '/')) == NULL)
630 				snprintf(realname, MAXPATHLEN, "%s", name);
631 			else
632 				havedir = 1;
633 		}
634 	} else {
635 		if (ISDOT(name) || ISDOTDOT(name))
636 			(void)realpath(name, realname);
637 		else {
638 			if ((dirname = strrchr(name, '/')) == NULL) {
639 				if ((realpath(name, realname)) == NULL)
640 					return (NULL);
641 			} else
642 				havedir = 1;
643 		}
644 	}
645 	if (havedir) {
646 		*dirname++ = '\0';
647 		if (ISDOT(dirname)) {
648 			*dirname = '\0';
649 			if ((realpath(name, realname)) == NULL)
650 				return (NULL);
651 		} else if (ISDOTDOT(dirname)) {
652 			*--dirname = '/';
653 			if ((realpath(name, realname)) == NULL)
654 				return (NULL);
655 		} else {
656 			if ((realpath(name, realname)) == NULL)
657 				return (NULL);
658 			baselen = strlen(realname);
659 			dirlen = strlen(dirname);
660 			if (baselen + dirlen + 1 > MAXPATHLEN)
661 				return (NULL);
662 			if (realname[1] == '\0') {
663 				memmove(realname + 1, dirname, dirlen);
664 				realname[dirlen + 1] = '\0';
665 			} else {
666 				realname[baselen] = '/';
667 				memmove(realname + baselen + 1,
668 				    dirname, dirlen);
669 				realname[baselen + dirlen + 1] = '\0';
670 			}
671 		}
672 	}
673 	return (realname);
674 }
675 
676 /*
677  * xdr routines for mount rpc's
678  */
679 int
680 xdr_dir(XDR *xdrsp, char *dirp)
681 {
682 
683 	return (xdr_string(xdrsp, &dirp, RPCMNT_PATHLEN));
684 }
685 
686 void
687 usage()
688 {
689 
690 	(void)fprintf(stderr, "%s\n%s\n",
691 	    "usage: umount [-fv] special | node",
692 	    "       umount -a | -A [-fv] [-h host] [-t type]");
693 	exit(1);
694 }
695