umount.c revision 80118 
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 80118 2001-07-22 00:45:29Z 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	mtablist *mtabhead;
72struct  addrinfo *nfshost_ai = NULL;
73int	fflag, vflag;
74char   *nfshost;
75
76void	 checkmntlist (char *, char **, char **, char **);
77int	 checkvfsname (const char *, char **);
78char	*getmntname (const char *, const char *,
79	 mntwhat, char **, dowhat);
80char 	*getrealname(char *, char *resolved_path);
81char   **makevfslist (const char *);
82size_t	 mntinfo (struct statfs **);
83int	 namematch (struct addrinfo *);
84int	 sacmp (struct sockaddr *, struct sockaddr *);
85int	 umountall (char **);
86int	 checkname (char *, char **);
87int	 umountfs (char *, char *, char *);
88void	 usage (void);
89int	 xdr_dir (XDR *, char *);
90
91int
92main(int argc, char *argv[])
93{
94	int all, errs, ch, mntsize, error;
95	char **typelist = NULL, *mntonname, *mntfromname;
96	char *type, *mntfromnamerev, *mntonnamerev;
97	struct statfs *mntbuf;
98	struct addrinfo hints;
99
100	/* Start disks transferring immediately. */
101	sync();
102
103	all = errs = 0;
104	while ((ch = getopt(argc, argv, "Aafh:t:v")) != -1)
105		switch (ch) {
106		case 'A':
107			all = 2;
108			break;
109		case 'a':
110			all = 1;
111			break;
112		case 'f':
113			fflag = MNT_FORCE;
114			break;
115		case 'h':	/* -h implies -A. */
116			all = 2;
117			nfshost = optarg;
118			break;
119		case 't':
120			if (typelist != NULL)
121				err(1, "only one -t option may be specified");
122			typelist = makevfslist(optarg);
123			break;
124		case 'v':
125			vflag = 1;
126			break;
127		default:
128			usage();
129			/* NOTREACHED */
130		}
131	argc -= optind;
132	argv += optind;
133
134	if ((argc == 0 && !all) || (argc != 0 && all))
135		usage();
136
137	/* -h implies "-t nfs" if no -t flag. */
138	if ((nfshost != NULL) && (typelist == NULL))
139		typelist = makevfslist("nfs");
140
141	if (nfshost != NULL) {
142		memset(&hints, 0, sizeof hints);
143		error = getaddrinfo(nfshost, NULL, &hints, &nfshost_ai);
144		errx(1, "%s: %s", nfshost, gai_strerror(error));
145	}
146
147	switch (all) {
148	case 2:
149		if ((mntsize = mntinfo(&mntbuf)) <= 0)
150			break;
151		/*
152		 * We unmount the nfs-mounts in the reverse order
153		 * that they were mounted.
154		 */
155		for (errs = 0, mntsize--; mntsize > 0; mntsize--) {
156			if (checkvfsname(mntbuf[mntsize].f_fstypename,
157			    typelist))
158				continue;
159			/*
160			 * Check if a mountpoint is laid over by another mount.
161			 * A warning will be printed to stderr if this is
162			 * the case. The laid over mount remains unmounted.
163			 */
164			mntonname = mntbuf[mntsize].f_mntonname;
165			mntfromname = mntbuf[mntsize].f_mntfromname;
166			mntonnamerev = getmntname(getmntname(mntonname,
167			    NULL, MNTFROM, &type, NAME), NULL,
168			    MNTON, &type, NAME);
169
170			mntfromnamerev = getmntname(mntonnamerev,
171			    NULL, MNTFROM, &type, NAME);
172
173			if (strcmp(mntonnamerev, mntonname) == 0 &&
174			    strcmp(mntfromnamerev, mntfromname ) != 0)
175				warnx("cannot umount %s, %s\n        "
176				    "is mounted there, umount it first",
177				    mntonname, mntfromnamerev);
178
179			if (checkname(mntbuf[mntsize].f_mntonname,
180			    typelist) != 0)
181				errs = 1;
182		}
183		free(mntbuf);
184		break;
185	case 1:
186		if (setfsent() == 0)
187			err(1, "%s", _PATH_FSTAB);
188		errs = umountall(typelist);
189		break;
190	case 0:
191		for (errs = 0; *argv != NULL; ++argv)
192			if (checkname(*argv, typelist) != 0)
193				errs = 1;
194		break;
195	}
196	(void)getmntname(NULL, NULL, NOTHING, NULL, FREE);
197	exit(errs);
198}
199
200int
201umountall(char **typelist)
202{
203	struct vfsconf vfc;
204	struct fstab *fs;
205	int rval;
206	char *cp;
207	static int firstcall = 1;
208
209	if ((fs = getfsent()) != NULL)
210		firstcall = 0;
211	else if (firstcall)
212		errx(1, "fstab reading failure");
213	else
214		return (0);
215	do {
216		/* Ignore the root. */
217		if (strcmp(fs->fs_file, "/") == 0)
218			continue;
219		/*
220		 * !!!
221		 * Historic practice: ignore unknown FSTAB_* fields.
222		 */
223		if (strcmp(fs->fs_type, FSTAB_RW) &&
224		    strcmp(fs->fs_type, FSTAB_RO) &&
225		    strcmp(fs->fs_type, FSTAB_RQ))
226			continue;
227		/* Ignore unknown file system types. */
228		if (getvfsbyname(fs->fs_vfstype, &vfc) == -1)
229			continue;
230		if (checkvfsname(fs->fs_vfstype, typelist))
231			continue;
232
233		/*
234		 * We want to unmount the file systems in the reverse order
235		 * that they were mounted.  So, we save off the file name
236		 * in some allocated memory, and then call recursively.
237		 */
238		if ((cp = malloc((size_t)strlen(fs->fs_file) + 1)) == NULL)
239			err(1, "malloc failed");
240		(void)strcpy(cp, fs->fs_file);
241		rval = umountall(typelist);
242		rval = checkname(cp, typelist) || rval;
243		free(cp);
244		return (rval);
245	} while ((fs = getfsent()) != NULL);
246	return (0);
247}
248
249/*
250 * Do magic checks on mountpoint and device or hand over
251 * it to unmount(2) if everything fails.
252 */
253int
254checkname(char *name, char **typelist)
255{
256	size_t len;
257	int speclen;
258	char *mntonname, *mntfromname;
259	char *mntfromnamerev;
260	char *resolved, realname[MAXPATHLEN];
261	char *type, *hostp, *delimp, *origname;
262
263	len = 0;
264	mntfromname = mntonname = delimp = hostp = NULL;
265
266	/*
267	 * 1. Check if the name exists in the mounttable.
268	 */
269	(void)checkmntlist(name, &mntfromname, &mntonname, &type);
270	/*
271	 * 2. Remove trailing slashes if there are any. After that
272	 * we look up the name in the mounttable again.
273	 */
274	if (mntfromname == NULL && mntonname == NULL) {
275		speclen = strlen(name);
276		for (speclen = strlen(name);
277		    speclen > 1 && name[speclen - 1] == '/';
278		    speclen--)
279			name[speclen - 1] = '\0';
280		(void)checkmntlist(name, &mntfromname, &mntonname, &type);
281		resolved = name;
282		/* Save off original name in origname */
283		if ((origname = strdup(name)) == NULL)
284			err(1, "strdup");
285		/*
286		 * 3. Check if the deprecated nfs-syntax with an '@'
287		 * has been used and translate it to the ':' syntax.
288		 * Look up the name in the mounttable again.
289		 */
290		if (mntfromname == NULL && mntonname == NULL) {
291			if ((delimp = strrchr(name, '@')) != NULL) {
292				hostp = delimp + 1;
293				if (*hostp != '\0') {
294					/*
295					 * Make both '@' and ':'
296					 * notations equal
297					 */
298					char *host = strdup(hostp);
299					len = strlen(hostp);
300					if (host == NULL)
301						err(1, "strdup");
302					memmove(name + len + 1, name,
303					    (size_t)(delimp - name));
304					name[len] = ':';
305					memmove(name, host, len);
306					free(host);
307				}
308				for (speclen = strlen(name);
309				    speclen > 1 && name[speclen - 1] == '/';
310				    speclen--)
311					name[speclen - 1] = '\0';
312				name[len + speclen + 1] = '\0';
313				(void)checkmntlist(name, &mntfromname,
314				    &mntonname, &type);
315				resolved = name;
316			}
317			/*
318			 * 4. Check if a relative mountpoint has been
319			 * specified. This should happen as last check,
320			 * the order is important. To prevent possible
321			 * nfs-hangs, we just call realpath(3) on the
322			 * basedir of mountpoint and add the dirname again.
323			 * Check the name in mounttable one last time.
324			 */
325			if (mntfromname == NULL && mntonname == NULL) {
326				(void)strcpy(name, origname);
327				if ((getrealname(name, realname)) != NULL) {
328					(void)checkmntlist(realname,
329					    &mntfromname, &mntonname, &type);
330					resolved = realname;
331				}
332				/*
333				 * 5. All tests failed, just hand over the
334				 * mountpoint to the kernel, maybe the statfs
335				 * structure has been truncated or is not
336				 * useful anymore because of a chroot(2).
337				 * Please note that nfs will not be able to
338				 * notify the nfs-server about unmounting.
339				 * These things can change in future when the
340				 * fstat structure get's more reliable,
341				 * but at the moment we cannot thrust it.
342				 */
343				if (mntfromname == NULL && mntonname == NULL) {
344					(void)strcpy(name, origname);
345					if (umountfs(NULL, origname,
346					    "none") == 0) {;
347						warnx("%s not found in "
348						    "mount table, "
349						    "unmounted it anyway",
350						    origname);
351						free(origname);
352						return (0);
353					} else
354						free(origname);
355						return (1);
356				}
357			}
358		}
359		free(origname);
360	} else
361		resolved = name;
362
363	if (checkvfsname(type, typelist))
364		return (1);
365
366	/*
367	 * Check if the reverse entrys of the mounttable are really the
368	 * same as the normal ones.
369	 */
370	if ((mntfromnamerev = strdup(getmntname(getmntname(mntfromname,
371	    NULL, MNTON, &type, NAME), NULL, MNTFROM, &type, NAME))) == NULL)
372		err(1, "strdup");
373	/*
374	 * Mark the uppermost mount as unmounted.
375	 */
376	(void)getmntname(mntfromname, mntonname, NOTHING, &type, MARK);
377	/*
378	 * If several equal mounts are in the mounttable, check the order
379	 * and warn the user if necessary.
380	 */
381	if (strcmp(mntfromnamerev, mntfromname ) != 0 &&
382	    strcmp(resolved, mntonname) != 0) {
383		warnx("cannot umount %s, %s\n        "
384		    "is mounted there, umount it first",
385		    mntonname, mntfromnamerev);
386
387		/* call getmntname again to set mntcheck[i] to 0 */
388		(void)getmntname(mntfromname, mntonname,
389		    NOTHING, &type, UNMARK);
390		return (1);
391	}
392	free(mntfromnamerev);
393	return (umountfs(mntfromname, mntonname, type));
394}
395
396/*
397 * NFS stuff and unmount(2) call
398 */
399int
400umountfs(char *mntfromname, char *mntonname, char *type)
401{
402	enum clnt_stat clnt_stat;
403	struct timeval try;
404	struct addrinfo *ai, hints;
405	int do_rpc;
406	CLIENT *clp;
407	char *nfsdirname, *orignfsdirname;
408	char *hostp, *delimp;
409
410	ai = NULL;
411	do_rpc = 0;
412	hostp = NULL;
413	nfsdirname = delimp = orignfsdirname = NULL;
414	memset(&hints, 0, sizeof hints);
415
416	if (strcmp(type, "nfs") == 0) {
417		if ((nfsdirname = strdup(mntfromname)) == NULL)
418			err(1, "strdup");
419		orignfsdirname = nfsdirname;
420		if ((delimp = strrchr(nfsdirname, ':')) != NULL) {
421			*delimp = '\0';
422			hostp = nfsdirname;
423			getaddrinfo(hostp, NULL, &hints, &ai);
424			if (ai == NULL) {
425				warnx("can't get net id for host");
426			}
427			nfsdirname = delimp + 1;
428		}
429
430		/*
431		 * Check if we have to start the rpc-call later.
432		 * If there are still identical nfs-names mounted,
433		 * we skip the rpc-call. Obviously this has to
434		 * happen before unmount(2), but it should happen
435		 * after the previous namecheck.
436		 * A non-NULL return means that this is the last
437		 * mount from mntfromname that is still mounted.
438		 */
439		if (getmntname(mntfromname, NULL, NOTHING, &type, COUNT)
440		     != NULL)
441			do_rpc = 1;
442	}
443
444	if (!namematch(ai))
445		return (1);
446	if (unmount(mntonname, fflag) != 0 ) {
447		warn("unmount of %s failed", mntonname);
448		return (1);
449	}
450	if (vflag)
451		(void)printf("%s: unmount from %s\n", mntfromname, mntonname);
452	/*
453	 * Report to mountd-server which nfsname
454	 * has been unmounted.
455	 */
456	if (ai != NULL && !(fflag & MNT_FORCE) && do_rpc) {
457		clp = clnt_create(hostp, RPCPROG_MNT, RPCMNT_VER1, "udp");
458		if (clp  == NULL) {
459			warnx("%s: %s", hostp,
460			    clnt_spcreateerror("RPCPROG_MNT"));
461			return (1);
462		}
463		clp->cl_auth = authsys_create_default();
464		try.tv_sec = 20;
465		try.tv_usec = 0;
466		clnt_stat = clnt_call(clp, RPCMNT_UMOUNT, xdr_dir,
467		    nfsdirname, xdr_void, (caddr_t)0, try);
468		if (clnt_stat != RPC_SUCCESS) {
469			warnx("%s: %s", hostp,
470			    clnt_sperror(clp, "RPCMNT_UMOUNT"));
471			return (1);
472		}
473		/*
474		 * Remove the unmounted entry from /var/db/mounttab.
475		 */
476		if (read_mtab(NULL)) {
477			clean_mtab(hostp, nfsdirname);
478			if(!write_mtab())
479				warnx("cannot remove mounttab entry %s:%s",
480				    hostp, nfsdirname);
481			free_mtab();
482		}
483		free(orignfsdirname);
484		auth_destroy(clp->cl_auth);
485		clnt_destroy(clp);
486	}
487	return (0);
488}
489
490char *
491getmntname(const char *fromname, const char *onname,
492    mntwhat what, char **type, dowhat mark)
493{
494	static struct statfs *mntbuf;
495	static size_t mntsize = 0;
496	static char *mntcheck = NULL;
497	static char *mntcount = NULL;
498	int i, count;
499
500	if (mntsize <= 0) {
501		if ((mntsize = mntinfo(&mntbuf)) <= 0)
502			return (NULL);
503	}
504	if (mntcheck == NULL) {
505		if ((mntcheck = calloc(mntsize + 1, sizeof(int))) == NULL ||
506		    (mntcount = calloc(mntsize + 1, sizeof(int))) == NULL)
507			err(1, "calloc");
508	}
509	/*
510	 * We want to get the file systems in the reverse order
511	 * that they were mounted. Mounted and unmounted filesystems
512	 * are marked or unmarked in a table called 'mntcheck'.
513	 * Unmount(const char *dir, int flags) does only take the
514	 * mountpoint as argument, not the destination. If we don't pay
515	 * attention to the order, it can happen that a overlaying
516	 * filesystem get's unmounted instead of the one the user
517	 * has choosen.
518	 */
519	switch (mark) {
520	case NAME:
521		/* Return only the specific name */
522		for (i = mntsize - 1; i >= 0; i--) {
523			if (fromname != NULL && what == MNTON &&
524			    !strcmp(mntbuf[i].f_mntfromname, fromname) &&
525			    mntcheck[i] != 1) {
526				if (type)
527					*type = mntbuf[i].f_fstypename;
528				return (mntbuf[i].f_mntonname);
529			}
530			if (fromname != NULL && what == MNTFROM &&
531			    !strcmp(mntbuf[i].f_mntonname, fromname) &&
532			    mntcheck[i] != 1) {
533				if (type)
534					*type = mntbuf[i].f_fstypename;
535				return (mntbuf[i].f_mntfromname);
536			}
537		}
538		return (NULL);
539	case MARK:
540		/* Mark current mount with '1' and return name */
541		for (i = mntsize - 1; i >= 0; i--) {
542			if (mntcheck[i] == 0 &&
543			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
544			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
545				mntcheck[i] = 1;
546				return (mntbuf[i].f_mntonname);
547			}
548		}
549		return (NULL);
550	case UNMARK:
551		/* Unmark current mount with '0' and return name */
552		for (i = 0; i < mntsize; i++) {
553			if (mntcheck[i] == 1 &&
554			    (strcmp(mntbuf[i].f_mntonname, onname) == 0) &&
555			    (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)) {
556				mntcheck[i] = 0;
557				return (mntbuf[i].f_mntonname);
558			}
559		}
560		return (NULL);
561	case COUNT:
562		/* Count the equal mntfromnames */
563		count = 0;
564		for (i = mntsize - 1; i >= 0; i--) {
565			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0)
566				count++;
567		}
568		/* Mark the already unmounted mounts and return
569		 * mntfromname if count <= 1. Else return NULL.
570		 */
571		for (i = mntsize - 1; i >= 0; i--) {
572			if (strcmp(mntbuf[i].f_mntfromname, fromname) == 0) {
573				if (mntcount[i] == 1)
574					count--;
575				else {
576					mntcount[i] = 1;
577					break;
578				}
579			}
580		}
581		if (count <= 1)
582			return (mntbuf[i].f_mntonname);
583		else
584			return (NULL);
585	case FREE:
586		free(mntbuf);
587		free(mntcheck);
588		free(mntcount);
589		return (NULL);
590	default:
591		return (NULL);
592	}
593}
594
595int
596sacmp(struct sockaddr *sa1, struct sockaddr *sa2)
597{
598	void *p1, *p2;
599	int len;
600
601	if (sa1->sa_family != sa2->sa_family)
602		return (1);
603
604	switch (sa1->sa_family) {
605	case AF_INET:
606		p1 = &((struct sockaddr_in *)sa1)->sin_addr;
607		p2 = &((struct sockaddr_in *)sa2)->sin_addr;
608		len = 4;
609		break;
610	case AF_INET6:
611		p1 = &((struct sockaddr_in6 *)sa1)->sin6_addr;
612		p2 = &((struct sockaddr_in6 *)sa2)->sin6_addr;
613		len = 16;
614		if (((struct sockaddr_in6 *)sa1)->sin6_scope_id !=
615		    ((struct sockaddr_in6 *)sa2)->sin6_scope_id)
616			return (1);
617		break;
618	default:
619		return (1);
620	}
621
622	return memcmp(p1, p2, len);
623}
624
625int
626namematch(struct addrinfo *ai)
627{
628	struct addrinfo *aip;
629
630	if (nfshost == NULL || nfshost_ai == NULL)
631		return (1);
632
633	while (ai != NULL) {
634		aip = nfshost_ai;
635		while (aip != NULL) {
636			if (sacmp(ai->ai_addr, aip->ai_addr) == 0)
637				return (1);
638			aip = aip->ai_next;
639		}
640		ai = ai->ai_next;
641	}
642
643	return (0);
644}
645
646void
647checkmntlist(char *name, char **fromname, char **onname, char **type)
648{
649
650	*fromname = getmntname(name, NULL, MNTFROM, type, NAME);
651	if (*fromname == NULL) {
652		*onname = getmntname(name, NULL, MNTON, type, NAME);
653		if (*onname != NULL)
654			*fromname = name;
655	} else
656		*onname = name;
657}
658
659size_t
660mntinfo(struct statfs **mntbuf)
661{
662	static struct statfs *origbuf;
663	size_t bufsize;
664	int mntsize;
665
666	mntsize = getfsstat(NULL, 0, MNT_NOWAIT);
667	if (mntsize <= 0)
668		return (0);
669	bufsize = (mntsize + 1) * sizeof(struct statfs);
670	if ((origbuf = malloc(bufsize)) == NULL)
671		err(1, "malloc");
672	mntsize = getfsstat(origbuf, (long)bufsize, MNT_NOWAIT);
673	*mntbuf = origbuf;
674	return (mntsize);
675}
676
677char *
678getrealname(char *name, char *realname)
679{
680	char *dirname;
681	int havedir;
682	size_t baselen;
683	size_t dirlen;
684
685	dirname = '\0';
686	havedir = 0;
687	if (*name == '/') {
688		if (ISDOT(name + 1) || ISDOTDOT(name + 1))
689			strcpy(realname, "/");
690		else {
691			if ((dirname = strrchr(name + 1, '/')) == NULL)
692				snprintf(realname, MAXPATHLEN, "%s", name);
693			else
694				havedir = 1;
695		}
696	} else {
697		if (ISDOT(name) || ISDOTDOT(name))
698			(void)realpath(name, realname);
699		else {
700			if ((dirname = strrchr(name, '/')) == NULL) {
701				if ((realpath(name, realname)) == NULL)
702					return (NULL);
703			} else
704				havedir = 1;
705		}
706	}
707	if (havedir) {
708		*dirname++ = '\0';
709		if (ISDOT(dirname)) {
710			*dirname = '\0';
711			if ((realpath(name, realname)) == NULL)
712				return (NULL);
713		} else if (ISDOTDOT(dirname)) {
714			*--dirname = '/';
715			if ((realpath(name, realname)) == NULL)
716				return (NULL);
717		} else {
718			if ((realpath(name, realname)) == NULL)
719				return (NULL);
720			baselen = strlen(realname);
721			dirlen = strlen(dirname);
722			if (baselen + dirlen + 1 > MAXPATHLEN)
723				return (NULL);
724			if (realname[1] == '\0') {
725				memmove(realname + 1, dirname, dirlen);
726				realname[dirlen + 1] = '\0';
727			} else {
728				realname[baselen] = '/';
729				memmove(realname + baselen + 1,
730				    dirname, dirlen);
731				realname[baselen + dirlen + 1] = '\0';
732			}
733		}
734	}
735	return (realname);
736}
737
738/*
739 * xdr routines for mount rpc's
740 */
741int
742xdr_dir(XDR *xdrsp, char *dirp)
743{
744
745	return (xdr_string(xdrsp, &dirp, RPCMNT_PATHLEN));
746}
747
748void
749usage()
750{
751
752	(void)fprintf(stderr, "%s\n%s\n",
753	    "usage: umount [-fv] special | node",
754	    "       umount -a | -A [-fv] [-h host] [-t type]");
755	exit(1);
756}
757