umount.c revision 80146 
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
35static 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
42static char sccsid[] = "@(#)umount.c	8.8 (Berkeley) 5/8/95";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/sbin/umount/umount.c 80146 2001-07-22 12:17:51Z iedowse $";
46#endif /* not lint */
47
48#include <sys/param.h>
49#include <sys/mount.h>
50#include <sys/socket.h>
51
52#include <netdb.h>
53#include <rpc/rpc.h>
54#include <nfs/rpcv2.h>
55
56#include <err.h>
57#include <fstab.h>
58#include <stdio.h>
59#include <stdlib.h>
60#include <string.h>
61#include <unistd.h>
62
63#include "mounttab.h"
64
65#define ISDOT(x)	((x)[0] == '.' && (x)[1] == '\0')
66#define ISDOTDOT(x)	((x)[0] == '.' && (x)[1] == '.' && (x)[2] == '\0')
67
68typedef enum { MNTON, MNTFROM, NOTHING } mntwhat;
69typedef enum { MARK, UNMARK, NAME, COUNT, FREE } dowhat;
70
71struct  addrinfo *nfshost_ai = NULL;
72int	fflag, vflag;
73char   *nfshost;
74
75void	 checkmntlist (char *, char **, char **, char **);
76int	 checkvfsname (const char *, char **);
77char	*getmntname (const char *, const char *,
78	 mntwhat, char **, dowhat);
79char 	*getrealname(char *, char *resolved_path);
80char   **makevfslist (const char *);
81size_t	 mntinfo (struct statfs **);
82int	 namematch (struct addrinfo *);
83int	 sacmp (struct sockaddr *, struct sockaddr *);
84int	 umountall (char **);
85int	 checkname (char *, char **);
86int	 umountfs (char *, char *, char *);
87void	 usage (void);
88int	 xdr_dir (XDR *, char *);
89
90int
91main(int argc, char *argv[])
92{
93	int all, errs, ch, mntsize, error;
94	char **typelist = NULL, *mntonname, *mntfromname;
95	char *type, *mntfromnamerev, *mntonnamerev;
96	struct statfs *mntbuf;
97	struct addrinfo hints;
98
99	/* Start disks transferring immediately. */
100	sync();
101
102	all = errs = 0;
103	while ((ch = getopt(argc, argv, "Aafh:t:v")) != -1)
104		switch (ch) {
105		case 'A':
106			all = 2;
107			break;
108		case 'a':
109			all = 1;
110			break;
111		case 'f':
112			fflag = MNT_FORCE;
113			break;
114		case 'h':	/* -h implies -A. */
115			all = 2;
116			nfshost = optarg;
117			break;
118		case 't':
119			if (typelist != NULL)
120				err(1, "only one -t option may be specified");
121			typelist = makevfslist(optarg);
122			break;
123		case 'v':
124			vflag = 1;
125			break;
126		default:
127			usage();
128			/* NOTREACHED */
129		}
130	argc -= optind;
131	argv += optind;
132
133	if ((argc == 0 && !all) || (argc != 0 && all))
134		usage();
135
136	/* -h implies "-t nfs" if no -t flag. */
137	if ((nfshost != NULL) && (typelist == NULL))
138		typelist = makevfslist("nfs");
139
140	if (nfshost != NULL) {
141		memset(&hints, 0, sizeof hints);
142		error = getaddrinfo(nfshost, NULL, &hints, &nfshost_ai);
143		errx(1, "%s: %s", nfshost, gai_strerror(error));
144	}
145
146	switch (all) {
147	case 2:
148		if ((mntsize = mntinfo(&mntbuf)) <= 0)
149			break;
150		/*
151		 * We unmount the nfs-mounts in the reverse order
152		 * that they were mounted.
153		 */
154		for (errs = 0, mntsize--; mntsize > 0; mntsize--) {
155			if (checkvfsname(mntbuf[mntsize].f_fstypename,
156			    typelist))
157				continue;
158			/*
159			 * Check if a mountpoint is laid over by another mount.
160			 * A warning will be printed to stderr if this is
161			 * the case. The laid over mount remains unmounted.
162			 */
163			mntonname = mntbuf[mntsize].f_mntonname;
164			mntfromname = mntbuf[mntsize].f_mntfromname;
165			mntonnamerev = getmntname(getmntname(mntonname,
166			    NULL, MNTFROM, &type, NAME), NULL,
167			    MNTON, &type, NAME);
168
169			mntfromnamerev = getmntname(mntonnamerev,
170			    NULL, MNTFROM, &type, NAME);
171
172			if (strcmp(mntonnamerev, mntonname) == 0 &&
173			    strcmp(mntfromnamerev, mntfromname ) != 0)
174				warnx("cannot umount %s, %s\n        "
175				    "is mounted there, umount it first",
176				    mntonname, mntfromnamerev);
177
178			if (checkname(mntbuf[mntsize].f_mntonname,
179			    typelist) != 0)
180				errs = 1;
181		}
182		free(mntbuf);
183		break;
184	case 1:
185		if (setfsent() == 0)
186			err(1, "%s", _PATH_FSTAB);
187		errs = umountall(typelist);
188		break;
189	case 0:
190		for (errs = 0; *argv != NULL; ++argv)
191			if (checkname(*argv, typelist) != 0)
192				errs = 1;
193		break;
194	}
195	(void)getmntname(NULL, NULL, NOTHING, NULL, FREE);
196	exit(errs);
197}
198
199int
200umountall(char **typelist)
201{
202	struct vfsconf vfc;
203	struct fstab *fs;
204	int rval;
205	char *cp;
206	static int firstcall = 1;
207
208	if ((fs = getfsent()) != NULL)
209		firstcall = 0;
210	else if (firstcall)
211		errx(1, "fstab reading failure");
212	else
213		return (0);
214	do {
215		/* Ignore the root. */
216		if (strcmp(fs->fs_file, "/") == 0)
217			continue;
218		/*
219		 * !!!
220		 * Historic practice: ignore unknown FSTAB_* fields.
221		 */
222		if (strcmp(fs->fs_type, FSTAB_RW) &&
223		    strcmp(fs->fs_type, FSTAB_RO) &&
224		    strcmp(fs->fs_type, FSTAB_RQ))
225			continue;
226		/* Ignore unknown file system types. */
227		if (getvfsbyname(fs->fs_vfstype, &vfc) == -1)
228			continue;
229		if (checkvfsname(fs->fs_vfstype, typelist))
230			continue;
231
232		/*
233		 * We want to unmount the file systems in the reverse order
234		 * that they were mounted.  So, we save off the file name
235		 * in some allocated memory, and then call recursively.
236		 */
237		if ((cp = malloc((size_t)strlen(fs->fs_file) + 1)) == NULL)
238			err(1, "malloc failed");
239		(void)strcpy(cp, fs->fs_file);
240		rval = umountall(typelist);
241		rval = checkname(cp, typelist) || rval;
242		free(cp);
243		return (rval);
244	} while ((fs = getfsent()) != NULL);
245	return (0);
246}
247
248/*
249 * Do magic checks on mountpoint and device or hand over
250 * it to unmount(2) if everything fails.
251 */
252int
253checkname(char *name, char **typelist)
254{
255	size_t len;
256	int speclen;
257	char *mntonname, *mntfromname;
258	char *mntfromnamerev;
259	char *resolved, realname[MAXPATHLEN];
260	char *type, *hostp, *delimp, *origname;
261
262	len = 0;
263	mntfromname = mntonname = delimp = hostp = NULL;
264
265	/*
266	 * 1. Check if the name exists in the mounttable.
267	 */
268	(void)checkmntlist(name, &mntfromname, &mntonname, &type);
269	/*
270	 * 2. Remove trailing slashes if there are any. After that
271	 * we look up the name in the mounttable again.
272	 */
273	if (mntfromname == NULL && mntonname == NULL) {
274		speclen = strlen(name);
275		for (speclen = strlen(name);
276		    speclen > 1 && name[speclen - 1] == '/';
277		    speclen--)
278			name[speclen - 1] = '\0';
279		(void)checkmntlist(name, &mntfromname, &mntonname, &type);
280		resolved = name;
281		/* Save off original name in origname */
282		if ((origname = strdup(name)) == NULL)
283			err(1, "strdup");
284		/*
285		 * 3. Check if the deprecated nfs-syntax with an '@'
286		 * has been used and translate it to the ':' syntax.
287		 * Look up the name in the mounttable again.
288		 */
289		if (mntfromname == NULL && mntonname == NULL) {
290			if ((delimp = strrchr(name, '@')) != NULL) {
291				hostp = delimp + 1;
292				if (*hostp != '\0') {
293					/*
294					 * Make both '@' and ':'
295					 * notations equal
296					 */
297					char *host = strdup(hostp);
298					len = strlen(hostp);
299					if (host == NULL)
300						err(1, "strdup");
301					memmove(name + len + 1, name,
302					    (size_t)(delimp - name));
303					name[len] = ':';
304					memmove(name, host, len);
305					free(host);
306				}
307				for (speclen = strlen(name);
308				    speclen > 1 && name[speclen - 1] == '/';
309				    speclen--)
310					name[speclen - 1] = '\0';
311				name[len + speclen + 1] = '\0';
312				(void)checkmntlist(name, &mntfromname,
313				    &mntonname, &type);
314				resolved = name;
315			}
316			/*
317			 * 4. Check if a relative mountpoint has been
318			 * specified. This should happen as last check,
319			 * the order is important. To prevent possible
320			 * nfs-hangs, we just call realpath(3) on the
321			 * basedir of mountpoint and add the dirname again.
322			 * Check the name in mounttable one last time.
323			 */
324			if (mntfromname == NULL && mntonname == NULL) {
325				(void)strcpy(name, origname);
326				if ((getrealname(name, realname)) != NULL) {
327					(void)checkmntlist(realname,
328					    &mntfromname, &mntonname, &type);
329					resolved = realname;
330				}
331				/*
332				 * 5. All tests failed, just hand over the
333				 * mountpoint to the kernel, maybe the statfs
334				 * structure has been truncated or is not
335				 * useful anymore because of a chroot(2).
336				 * Please note that nfs will not be able to
337				 * notify the nfs-server about unmounting.
338				 * These things can change in future when the
339				 * fstat structure get's more reliable,
340				 * but at the moment we cannot thrust it.
341				 */
342				if (mntfromname == NULL && mntonname == NULL) {
343					(void)strcpy(name, origname);
344					if (umountfs(NULL, origname,
345					    "none") == 0) {;
346						warnx("%s not found in "
347						    "mount table, "
348						    "unmounted it anyway",
349						    origname);
350						free(origname);
351						return (0);
352					} else
353						free(origname);
354						return (1);
355				}
356			}
357		}
358		free(origname);
359	} else
360		resolved = name;
361
362	if (checkvfsname(type, typelist))
363		return (1);
364
365	/*
366	 * Check if the reverse entrys of the mounttable are really the
367	 * same as the normal ones.
368	 */
369	if ((mntfromnamerev = strdup(getmntname(getmntname(mntfromname,
370	    NULL, MNTON, &type, NAME), NULL, MNTFROM, &type, NAME))) == NULL)
371		err(1, "strdup");
372	/*
373	 * Mark the uppermost mount as unmounted.
374	 */
375	(void)getmntname(mntfromname, mntonname, NOTHING, &type, MARK);
376	/*
377	 * If several equal mounts are in the mounttable, check the order
378	 * and warn the user if necessary.
379	 */
380	if (strcmp(mntfromnamerev, mntfromname ) != 0 &&
381	    strcmp(resolved, mntonname) != 0) {
382		warnx("cannot umount %s, %s\n        "
383		    "is mounted there, umount it first",
384		    mntonname, mntfromnamerev);
385
386		/* call getmntname again to set mntcheck[i] to 0 */
387		(void)getmntname(mntfromname, mntonname,
388		    NOTHING, &type, UNMARK);
389		return (1);
390	}
391	free(mntfromnamerev);
392	return (umountfs(mntfromname, mntonname, type));
393}
394
395/*
396 * NFS stuff and unmount(2) call
397 */
398int
399umountfs(char *mntfromname, char *mntonname, char *type)
400{
401	enum clnt_stat clnt_stat;
402	struct timeval try;
403	struct addrinfo *ai, hints;
404	int do_rpc;
405	CLIENT *clp;
406	char *nfsdirname, *orignfsdirname;
407	char *hostp, *delimp;
408
409	ai = NULL;
410	do_rpc = 0;
411	hostp = NULL;
412	nfsdirname = delimp = orignfsdirname = NULL;
413	memset(&hints, 0, sizeof hints);
414
415	if (strcmp(type, "nfs") == 0) {
416		if ((nfsdirname = strdup(mntfromname)) == NULL)
417			err(1, "strdup");
418		orignfsdirname = nfsdirname;
419		if ((delimp = strrchr(nfsdirname, ':')) != NULL) {
420			*delimp = '\0';
421			hostp = nfsdirname;
422			getaddrinfo(hostp, NULL, &hints, &ai);
423			if (ai == NULL) {
424				warnx("can't get net id for host");
425			}
426			nfsdirname = delimp + 1;
427		}
428
429		/*
430		 * Check if we have to start the rpc-call later.
431		 * If there are still identical nfs-names mounted,
432		 * we skip the rpc-call. Obviously this has to
433		 * happen before unmount(2), but it should happen
434		 * after the previous namecheck.
435		 * A non-NULL return means that this is the last
436		 * mount from mntfromname that is still mounted.
437		 */
438		if (getmntname(mntfromname, NULL, NOTHING, &type, COUNT)
439		     != NULL)
440			do_rpc = 1;
441	}
442
443	if (!namematch(ai))
444		return (1);
445	if (unmount(mntonname, fflag) != 0 ) {
446		warn("unmount of %s failed", mntonname);
447		return (1);
448	}
449	if (vflag)
450		(void)printf("%s: unmount from %s\n", mntfromname, mntonname);
451	/*
452	 * Report to mountd-server which nfsname
453	 * has been unmounted.
454	 */
455	if (ai != NULL && !(fflag & MNT_FORCE) && do_rpc) {
456		clp = clnt_create(hostp, RPCPROG_MNT, RPCMNT_VER1, "udp");
457		if (clp  == NULL) {
458			warnx("%s: %s", hostp,
459			    clnt_spcreateerror("RPCPROG_MNT"));
460			return (1);
461		}
462		clp->cl_auth = authsys_create_default();
463		try.tv_sec = 20;
464		try.tv_usec = 0;
465		clnt_stat = clnt_call(clp, RPCMNT_UMOUNT, xdr_dir,
466		    nfsdirname, xdr_void, (caddr_t)0, try);
467		if (clnt_stat != RPC_SUCCESS) {
468			warnx("%s: %s", hostp,
469			    clnt_sperror(clp, "RPCMNT_UMOUNT"));
470			return (1);
471		}
472		/*
473		 * Remove the unmounted entry from /var/db/mounttab.
474		 */
475		if (read_mtab()) {
476			clean_mtab(hostp, nfsdirname, vflag);
477			if(!write_mtab(vflag))
478				warnx("cannot remove mounttab entry %s:%s",
479				    hostp, nfsdirname);
480			free_mtab();
481		}
482		free(orignfsdirname);
483		auth_destroy(clp->cl_auth);
484		clnt_destroy(clp);
485	}
486	return (0);
487}
488
489char *
490getmntname(const char *fromname, const char *onname,
491    mntwhat what, char **type, dowhat mark)
492{
493	static struct statfs *mntbuf;
494	static size_t mntsize = 0;
495	static char *mntcheck = NULL;
496	static char *mntcount = NULL;
497	int i, count;
498
499	if (mntsize <= 0) {
500		if ((mntsize = mntinfo(&mntbuf)) <= 0)
501			return (NULL);
502	}
503	if (mntcheck == NULL) {
504		if ((mntcheck = calloc(mntsize + 1, sizeof(int))) == NULL ||
505		    (mntcount = calloc(mntsize + 1, sizeof(int))) == NULL)
506			err(1, "calloc");
507	}
508	/*
509	 * We want to get the file systems in the reverse order
510	 * that they were mounted. Mounted and unmounted filesystems
511	 * are marked or unmarked in a table called 'mntcheck'.
512	 * Unmount(const char *dir, int flags) does only take the
513	 * mountpoint as argument, not the destination. If we don't pay
514	 * attention to the order, it can happen that a overlaying
515	 * filesystem get's unmounted instead of the one the user
516	 * has choosen.
517	 */
518	switch (mark) {
519	case NAME:
520		/* Return only the specific name */
521		for (i = mntsize - 1; i >= 0; i--) {
522			if (fromname != NULL && what == MNTON &&
523			    !strcmp(mntbuf[i].f_mntfromname, fromname) &&
524			    mntcheck[i] != 1) {
525				if (type)
526					*type = mntbuf[i].f_fstypename;
527				return (mntbuf[i].f_mntonname);
528			}
529			if (fromname != NULL && what == MNTFROM &&
530			    !strcmp(mntbuf[i].f_mntonname, fromname) &&
531			    mntcheck[i] != 1) {
532				if (type)
533					*type = mntbuf[i].f_fstypename;
534				return (mntbuf[i].f_mntfromname);
535			}
536		}
537		return (NULL);
538	case MARK:
539		/* Mark current mount with '1' and return name */
540		for (i = mntsize - 1; i >= 0; i--) {
541			if (mntcheck[i] == 0 &&
542			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
543			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
544				mntcheck[i] = 1;
545				return (mntbuf[i].f_mntonname);
546			}
547		}
548		return (NULL);
549	case UNMARK:
550		/* Unmark current mount with '0' and return name */
551		for (i = 0; i < mntsize; i++) {
552			if (mntcheck[i] == 1 &&
553			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
554			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
555				mntcheck[i] = 0;
556				return (mntbuf[i].f_mntonname);
557			}
558		}
559		return (NULL);
560	case COUNT:
561		/* Count the equal mntfromnames */
562		count = 0;
563		for (i = mntsize - 1; i >= 0; i--) {
564			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)
565				count++;
566		}
567		/* Mark the already unmounted mounts and return
568		 * mntfromname if count <= 1. Else return NULL.
569		 */
570		for (i = mntsize - 1; i >= 0; i--) {
571			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0) {
572				if (mntcount[i] == 1)
573					count--;
574				else {
575					mntcount[i] = 1;
576					break;
577				}
578			}
579		}
580		if (count <= 1)
581			return (mntbuf[i].f_mntonname);
582		else
583			return (NULL);
584	case FREE:
585		free(mntbuf);
586		free(mntcheck);
587		free(mntcount);
588		return (NULL);
589	default:
590		return (NULL);
591	}
592}
593
594int
595sacmp(struct sockaddr *sa1, struct sockaddr *sa2)
596{
597	void *p1, *p2;
598	int len;
599
600	if (sa1->sa_family != sa2->sa_family)
601		return (1);
602
603	switch (sa1->sa_family) {
604	case AF_INET:
605		p1 = &((struct sockaddr_in *)sa1)->sin_addr;
606		p2 = &((struct sockaddr_in *)sa2)->sin_addr;
607		len = 4;
608		break;
609	case AF_INET6:
610		p1 = &((struct sockaddr_in6 *)sa1)->sin6_addr;
611		p2 = &((struct sockaddr_in6 *)sa2)->sin6_addr;
612		len = 16;
613		if (((struct sockaddr_in6 *)sa1)->sin6_scope_id !=
614		    ((struct sockaddr_in6 *)sa2)->sin6_scope_id)
615			return (1);
616		break;
617	default:
618		return (1);
619	}
620
621	return memcmp(p1, p2, len);
622}
623
624int
625namematch(struct addrinfo *ai)
626{
627	struct addrinfo *aip;
628
629	if (nfshost == NULL || nfshost_ai == NULL)
630		return (1);
631
632	while (ai != NULL) {
633		aip = nfshost_ai;
634		while (aip != NULL) {
635			if (sacmp(ai->ai_addr, aip->ai_addr) == 0)
636				return (1);
637			aip = aip->ai_next;
638		}
639		ai = ai->ai_next;
640	}
641
642	return (0);
643}
644
645void
646checkmntlist(char *name, char **fromname, char **onname, char **type)
647{
648
649	*fromname = getmntname(name, NULL, MNTFROM, type, NAME);
650	if (*fromname == NULL) {
651		*onname = getmntname(name, NULL, MNTON, type, NAME);
652		if (*onname != NULL)
653			*fromname = name;
654	} else
655		*onname = name;
656}
657
658size_t
659mntinfo(struct statfs **mntbuf)
660{
661	static struct statfs *origbuf;
662	size_t bufsize;
663	int mntsize;
664
665	mntsize = getfsstat(NULL, 0, MNT_NOWAIT);
666	if (mntsize <= 0)
667		return (0);
668	bufsize = (mntsize + 1) * sizeof(struct statfs);
669	if ((origbuf = malloc(bufsize)) == NULL)
670		err(1, "malloc");
671	mntsize = getfsstat(origbuf, (long)bufsize, MNT_NOWAIT);
672	*mntbuf = origbuf;
673	return (mntsize);
674}
675
676char *
677getrealname(char *name, char *realname)
678{
679	char *dirname;
680	int havedir;
681	size_t baselen;
682	size_t dirlen;
683
684	dirname = '\0';
685	havedir = 0;
686	if (*name == '/') {
687		if (ISDOT(name + 1) || ISDOTDOT(name + 1))
688			strcpy(realname, "/");
689		else {
690			if ((dirname = strrchr(name + 1, '/')) == NULL)
691				snprintf(realname, MAXPATHLEN, "%s", name);
692			else
693				havedir = 1;
694		}
695	} else {
696		if (ISDOT(name) || ISDOTDOT(name))
697			(void)realpath(name, realname);
698		else {
699			if ((dirname = strrchr(name, '/')) == NULL) {
700				if ((realpath(name, realname)) == NULL)
701					return (NULL);
702			} else
703				havedir = 1;
704		}
705	}
706	if (havedir) {
707		*dirname++ = '\0';
708		if (ISDOT(dirname)) {
709			*dirname = '\0';
710			if ((realpath(name, realname)) == NULL)
711				return (NULL);
712		} else if (ISDOTDOT(dirname)) {
713			*--dirname = '/';
714			if ((realpath(name, realname)) == NULL)
715				return (NULL);
716		} else {
717			if ((realpath(name, realname)) == NULL)
718				return (NULL);
719			baselen = strlen(realname);
720			dirlen = strlen(dirname);
721			if (baselen + dirlen + 1 > MAXPATHLEN)
722				return (NULL);
723			if (realname[1] == '\0') {
724				memmove(realname + 1, dirname, dirlen);
725				realname[dirlen + 1] = '\0';
726			} else {
727				realname[baselen] = '/';
728				memmove(realname + baselen + 1,
729				    dirname, dirlen);
730				realname[baselen + dirlen + 1] = '\0';
731			}
732		}
733	}
734	return (realname);
735}
736
737/*
738 * xdr routines for mount rpc's
739 */
740int
741xdr_dir(XDR *xdrsp, char *dirp)
742{
743
744	return (xdr_string(xdrsp, &dirp, RPCMNT_PATHLEN));
745}
746
747void
748usage()
749{
750
751	(void)fprintf(stderr, "%s\n%s\n",
752	    "usage: umount [-fv] special | node",
753	    "       umount -a | -A [-fv] [-h host] [-t type]");
754	exit(1);
755}
756