xref: /freebsd/sbin/mdmfs/mdmfs.c (revision a25896ca1270e25b657ceaa8d47d5699515f5c25)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2001 Dima Dorfman.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 /*
30  * mdmfs (md/MFS) is a wrapper around mdconfig(8),
31  * newfs(8), and mount(8) that mimics the command line option set of
32  * the deprecated mount_mfs(8).
33  */
34 
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include <sys/param.h>
39 #include <sys/linker.h>
40 #include <sys/mdioctl.h>
41 #include <sys/module.h>
42 #include <sys/mount.h>
43 #include <sys/stat.h>
44 #include <sys/wait.h>
45 
46 #include <assert.h>
47 #include <err.h>
48 #include <errno.h>
49 #include <fcntl.h>
50 #include <grp.h>
51 #include <inttypes.h>
52 #include <paths.h>
53 #include <pwd.h>
54 #include <stdarg.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <ctype.h>
59 #include <unistd.h>
60 
61 typedef enum { false, true } bool;
62 
63 struct mtpt_info {
64 	uid_t		 mi_uid;
65 	bool		 mi_have_uid;
66 	gid_t		 mi_gid;
67 	bool		 mi_have_gid;
68 	mode_t		 mi_mode;
69 	bool		 mi_have_mode;
70 	bool		 mi_forced_pw;
71 };
72 
73 static	bool debug;		/* Emit debugging information? */
74 static	bool loudsubs;		/* Suppress output from helper programs? */
75 static	bool norun;		/* Actually run the helper programs? */
76 static	int unit;      		/* The unit we're working with. */
77 static	const char *mdname;	/* Name of memory disk device (e.g., "md"). */
78 static	const char *mdsuffix;	/* Suffix of memory disk device (e.g., ".uzip"). */
79 static	size_t mdnamelen;	/* Length of mdname. */
80 static	const char *path_mdconfig =_PATH_MDCONFIG;
81 
82 static void	 argappend(char **, const char *, ...) __printflike(2, 3);
83 static void	 debugprintf(const char *, ...) __printflike(1, 2);
84 static void	 do_mdconfig_attach(const char *, const enum md_types);
85 static void	 do_mdconfig_attach_au(const char *, const enum md_types);
86 static void	 do_mdconfig_detach(void);
87 static void	 do_mount_md(const char *, const char *);
88 static void	 do_mount_tmpfs(const char *, const char *);
89 static void	 do_mtptsetup(const char *, struct mtpt_info *);
90 static void	 do_newfs(const char *);
91 static void	 extract_ugid(const char *, struct mtpt_info *);
92 static int	 run(int *, const char *, ...) __printflike(2, 3);
93 static const char *run_exitstr(int);
94 static int	 run_exitnumber(int);
95 static void	 usage(void);
96 
97 int
98 main(int argc, char **argv)
99 {
100 	struct mtpt_info mi;		/* Mountpoint info. */
101 	intmax_t mdsize;
102 	char *mdconfig_arg, *newfs_arg,	/* Args to helper programs. */
103 	    *mount_arg;
104 	enum md_types mdtype;		/* The type of our memory disk. */
105 	bool have_mdtype, mlmac;
106 	bool detach, softdep, autounit, newfs;
107 	const char *mtpoint, *size_arg, *unitstr;
108 	char *p;
109 	int ch, idx;
110 	void *set;
111 	unsigned long ul;
112 
113 	/* Misc. initialization. */
114 	(void)memset(&mi, '\0', sizeof(mi));
115 	detach = true;
116 	softdep = true;
117 	autounit = false;
118 	mlmac = false;
119 	newfs = true;
120 	have_mdtype = false;
121 	mdtype = MD_SWAP;
122 	mdname = MD_NAME;
123 	mdnamelen = strlen(mdname);
124 	mdsize = 0;
125 	/*
126 	 * Can't set these to NULL.  They may be passed to the
127 	 * respective programs without modification.  I.e., we may not
128 	 * receive any command-line options which will caused them to
129 	 * be modified.
130 	 */
131 	mdconfig_arg = strdup("");
132 	newfs_arg = strdup("");
133 	mount_arg = strdup("");
134 	size_arg = NULL;
135 
136 	/* If we were started as mount_mfs or mfs, imply -C. */
137 	if (strcmp(getprogname(), "mount_mfs") == 0 ||
138 	    strcmp(getprogname(), "mfs") == 0) {
139 		/* Make compatibility assumptions. */
140 		mi.mi_mode = 01777;
141 		mi.mi_have_mode = true;
142 	}
143 
144 	while ((ch = getopt(argc, argv,
145 	    "a:b:Cc:Dd:E:e:F:f:hi:LlMm:NnO:o:Pp:Ss:tT:Uv:w:X")) != -1)
146 		switch (ch) {
147 		case 'a':
148 			argappend(&newfs_arg, "-a %s", optarg);
149 			break;
150 		case 'b':
151 			argappend(&newfs_arg, "-b %s", optarg);
152 			break;
153 		case 'C':
154 			/* Ignored for compatibility. */
155 			break;
156 		case 'c':
157 			argappend(&newfs_arg, "-c %s", optarg);
158 			break;
159 		case 'D':
160 			detach = false;
161 			break;
162 		case 'd':
163 			argappend(&newfs_arg, "-d %s", optarg);
164 			break;
165 		case 'E':
166 			path_mdconfig = optarg;
167 			break;
168 		case 'e':
169 			argappend(&newfs_arg, "-e %s", optarg);
170 			break;
171 		case 'F':
172 			if (have_mdtype)
173 				usage();
174 			mdtype = MD_VNODE;
175 			have_mdtype = true;
176 			argappend(&mdconfig_arg, "-f %s", optarg);
177 			break;
178 		case 'f':
179 			argappend(&newfs_arg, "-f %s", optarg);
180 			break;
181 		case 'h':
182 			usage();
183 			break;
184 		case 'i':
185 			argappend(&newfs_arg, "-i %s", optarg);
186 			break;
187 		case 'L':
188 			loudsubs = true;
189 			break;
190 		case 'l':
191 			mlmac = true;
192 			argappend(&newfs_arg, "-l");
193 			break;
194 		case 'M':
195 			if (have_mdtype)
196 				usage();
197 			mdtype = MD_MALLOC;
198 			have_mdtype = true;
199 			break;
200 		case 'm':
201 			argappend(&newfs_arg, "-m %s", optarg);
202 			break;
203 		case 'N':
204 			norun = true;
205 			break;
206 		case 'n':
207 			argappend(&newfs_arg, "-n");
208 			break;
209 		case 'O':
210 			argappend(&newfs_arg, "-o %s", optarg);
211 			break;
212 		case 'o':
213 			argappend(&mount_arg, "-o %s", optarg);
214 			break;
215 		case 'P':
216 			newfs = false;
217 			break;
218 		case 'p':
219 			if ((set = setmode(optarg)) == NULL)
220 				usage();
221 			mi.mi_mode = getmode(set, S_IRWXU | S_IRWXG | S_IRWXO);
222 			mi.mi_have_mode = true;
223 			mi.mi_forced_pw = true;
224 			free(set);
225 			break;
226 		case 'S':
227 			softdep = false;
228 			break;
229 		case 's':
230 			size_arg = optarg;
231 			break;
232 		case 't':
233 			argappend(&newfs_arg, "-t");
234 			break;
235 		case 'T':
236 			argappend(&mount_arg, "-t %s", optarg);
237 			break;
238 		case 'U':
239 			softdep = true;
240 			break;
241 		case 'v':
242 			argappend(&newfs_arg, "-O %s", optarg);
243 			break;
244 		case 'w':
245 			extract_ugid(optarg, &mi);
246 			mi.mi_forced_pw = true;
247 			break;
248 		case 'X':
249 			debug = true;
250 			break;
251 		default:
252 			usage();
253 		}
254 	argc -= optind;
255 	argv += optind;
256 	if (argc < 2)
257 		usage();
258 
259 	/*
260 	 * Historically our size arg was passed directly to mdconfig, which
261 	 * treats a number without a suffix as a count of 512-byte sectors;
262 	 * tmpfs would treat it as a count of bytes.  To get predictable
263 	 * behavior for 'auto' we document that the size always uses mdconfig
264 	 * rules.  To make that work, decode the size here so it can be passed
265 	 * to either tmpfs or mdconfig as a count of bytes.
266 	 */
267 	if (size_arg != NULL) {
268 		mdsize = (intmax_t)strtoumax(size_arg, &p, 0);
269 		if (p == size_arg || (p[0] != 0 && p[1] != 0) || mdsize < 0)
270 			errx(1, "invalid size '%s'", size_arg);
271 		switch (*p) {
272 		case 'p':
273 		case 'P':
274 			mdsize *= 1024;
275 		case 't':
276 		case 'T':
277 			mdsize *= 1024;
278 		case 'g':
279 		case 'G':
280 			mdsize *= 1024;
281 		case 'm':
282 		case 'M':
283 			mdsize *= 1024;
284 		case 'k':
285 		case 'K':
286 			mdsize *= 1024;
287 		case 'b':
288 		case 'B':
289 			break;
290 		case '\0':
291 			mdsize *= 512;
292 			break;
293 		default:
294 			errx(1, "invalid size suffix on '%s'", size_arg);
295 		}
296 	}
297 
298 	/*
299 	 * Based on the command line 'md-device' either mount a tmpfs filesystem
300 	 * or configure the md device then format and mount a filesystem on it.
301 	 * If the device is 'auto' use tmpfs if it is available and there is no
302 	 * request for multilabel MAC (which tmpfs does not support).
303 	 */
304 	unitstr = argv[0];
305 	mtpoint = argv[1];
306 
307 	if (strcmp(unitstr, "auto") == 0) {
308 		if (mlmac)
309 			idx = -1; /* Must use md for mlmac. */
310 		else if ((idx = modfind("tmpfs")) == -1)
311 			idx = kldload("tmpfs");
312 		if (idx == -1)
313 			unitstr = "md";
314 		else
315 			unitstr = "tmpfs";
316 	}
317 
318 	if (strcmp(unitstr, "tmpfs") == 0) {
319 		if (size_arg != NULL && mdsize != 0)
320 			argappend(&mount_arg, "-o size=%jd", mdsize);
321 		do_mount_tmpfs(mount_arg, mtpoint);
322 	} else {
323 		if (size_arg != NULL)
324 			argappend(&mdconfig_arg, "-s %jdB", mdsize);
325 		if (strncmp(unitstr, "/dev/", 5) == 0)
326 			unitstr += 5;
327 		if (strncmp(unitstr, mdname, mdnamelen) == 0)
328 			unitstr += mdnamelen;
329 		if (!isdigit(*unitstr)) {
330 			autounit = true;
331 			unit = -1;
332 			mdsuffix = unitstr;
333 		} else {
334 			ul = strtoul(unitstr, &p, 10);
335 			if (ul == ULONG_MAX)
336 				errx(1, "bad device unit: %s", unitstr);
337 			unit = ul;
338 			mdsuffix = p;	/* can be empty */
339 		}
340 
341 		if (!have_mdtype)
342 			mdtype = MD_SWAP;
343 		if (softdep)
344 			argappend(&newfs_arg, "-U");
345 		if (mdtype != MD_VNODE && !newfs)
346 			errx(1, "-P requires a vnode-backed disk");
347 
348 		/* Do the work. */
349 		if (detach && !autounit)
350 			do_mdconfig_detach();
351 		if (autounit)
352 			do_mdconfig_attach_au(mdconfig_arg, mdtype);
353 		else
354 			do_mdconfig_attach(mdconfig_arg, mdtype);
355 		if (newfs)
356 			do_newfs(newfs_arg);
357 		do_mount_md(mount_arg, mtpoint);
358 	}
359 
360 	do_mtptsetup(mtpoint, &mi);
361 
362 	return (0);
363 }
364 
365 /*
366  * Append the expansion of 'fmt' to the buffer pointed to by '*dstp';
367  * reallocate as required.
368  */
369 static void
370 argappend(char **dstp, const char *fmt, ...)
371 {
372 	char *old, *new;
373 	va_list ap;
374 
375 	old = *dstp;
376 	assert(old != NULL);
377 
378 	va_start(ap, fmt);
379 	if (vasprintf(&new, fmt,ap) == -1)
380 		errx(1, "vasprintf");
381 	va_end(ap);
382 
383 	*dstp = new;
384 	if (asprintf(&new, "%s %s", old, new) == -1)
385 		errx(1, "asprintf");
386 	free(*dstp);
387 	free(old);
388 
389 	*dstp = new;
390 }
391 
392 /*
393  * If run-time debugging is enabled, print the expansion of 'fmt'.
394  * Otherwise, do nothing.
395  */
396 static void
397 debugprintf(const char *fmt, ...)
398 {
399 	va_list ap;
400 
401 	if (!debug)
402 		return;
403 	fprintf(stderr, "DEBUG: ");
404 	va_start(ap, fmt);
405 	vfprintf(stderr, fmt, ap);
406 	va_end(ap);
407 	fprintf(stderr, "\n");
408 	fflush(stderr);
409 }
410 
411 /*
412  * Attach a memory disk with a known unit.
413  */
414 static void
415 do_mdconfig_attach(const char *args, const enum md_types mdtype)
416 {
417 	int rv;
418 	const char *ta;		/* Type arg. */
419 
420 	switch (mdtype) {
421 	case MD_SWAP:
422 		ta = "-t swap";
423 		break;
424 	case MD_VNODE:
425 		ta = "-t vnode";
426 		break;
427 	case MD_MALLOC:
428 		ta = "-t malloc";
429 		break;
430 	default:
431 		abort();
432 	}
433 	rv = run(NULL, "%s -a %s%s -u %s%d", path_mdconfig, ta, args,
434 	    mdname, unit);
435 	if (rv)
436 		errx(1, "mdconfig (attach) exited %s %d", run_exitstr(rv),
437 		    run_exitnumber(rv));
438 }
439 
440 /*
441  * Attach a memory disk with an unknown unit; use autounit.
442  */
443 static void
444 do_mdconfig_attach_au(const char *args, const enum md_types mdtype)
445 {
446 	const char *ta;		/* Type arg. */
447 	char *linep, *linebuf; 	/* Line pointer, line buffer. */
448 	int fd;			/* Standard output of mdconfig invocation. */
449 	FILE *sfd;
450 	int rv;
451 	char *p;
452 	size_t linelen;
453 	unsigned long ul;
454 
455 	switch (mdtype) {
456 	case MD_SWAP:
457 		ta = "-t swap";
458 		break;
459 	case MD_VNODE:
460 		ta = "-t vnode";
461 		break;
462 	case MD_MALLOC:
463 		ta = "-t malloc";
464 		break;
465 	default:
466 		abort();
467 	}
468 	rv = run(&fd, "%s -a %s%s", path_mdconfig, ta, args);
469 	if (rv)
470 		errx(1, "mdconfig (attach) exited %s %d", run_exitstr(rv),
471 		    run_exitnumber(rv));
472 
473 	/* Receive the unit number. */
474 	if (norun) {	/* Since we didn't run, we can't read.  Fake it. */
475 		unit = 0;
476 		return;
477 	}
478 	sfd = fdopen(fd, "r");
479 	if (sfd == NULL)
480 		err(1, "fdopen");
481 	linep = fgetln(sfd, &linelen);
482 	if (linep == NULL && linelen < mdnamelen + 1)
483 		errx(1, "unexpected output from mdconfig (attach)");
484 	/* If the output format changes, we want to know about it. */
485 	assert(strncmp(linep, mdname, mdnamelen) == 0);
486 	linebuf = malloc(linelen - mdnamelen + 1);
487 	assert(linebuf != NULL);
488 	/* Can't use strlcpy because linep is not NULL-terminated. */
489 	strncpy(linebuf, linep + mdnamelen, linelen);
490 	linebuf[linelen] = '\0';
491 	ul = strtoul(linebuf, &p, 10);
492 	if (ul == ULONG_MAX || *p != '\n')
493 		errx(1, "unexpected output from mdconfig (attach)");
494 	unit = ul;
495 
496 	fclose(sfd);
497 	close(fd);
498 }
499 
500 /*
501  * Detach a memory disk.
502  */
503 static void
504 do_mdconfig_detach(void)
505 {
506 	int rv;
507 
508 	rv = run(NULL, "%s -d -u %s%d", path_mdconfig, mdname, unit);
509 	if (rv && debug)	/* This is allowed to fail. */
510 		warnx("mdconfig (detach) exited %s %d (ignored)",
511 		    run_exitstr(rv), run_exitnumber(rv));
512 }
513 
514 /*
515  * Mount the configured memory disk.
516  */
517 static void
518 do_mount_md(const char *args, const char *mtpoint)
519 {
520 	int rv;
521 
522 	rv = run(NULL, "%s%s /dev/%s%d%s %s", _PATH_MOUNT, args,
523 	    mdname, unit, mdsuffix, mtpoint);
524 	if (rv)
525 		errx(1, "mount exited %s %d", run_exitstr(rv),
526 		    run_exitnumber(rv));
527 }
528 
529 /*
530  * Mount the configured tmpfs.
531  */
532 static void
533 do_mount_tmpfs(const char *args, const char *mtpoint)
534 {
535 	int rv;
536 
537 	rv = run(NULL, "%s -t tmpfs %s tmp %s", _PATH_MOUNT, args, mtpoint);
538 	if (rv)
539 		errx(1, "tmpfs mount exited %s %d", run_exitstr(rv),
540 		    run_exitnumber(rv));
541 }
542 
543 /*
544  * Various configuration of the mountpoint.  Mostly, enact 'mip'.
545  */
546 static void
547 do_mtptsetup(const char *mtpoint, struct mtpt_info *mip)
548 {
549 	struct statfs sfs;
550 
551 	if (!mip->mi_have_mode && !mip->mi_have_uid && !mip->mi_have_gid)
552 		return;
553 
554 	if (!norun) {
555 		if (statfs(mtpoint, &sfs) == -1) {
556 			warn("statfs: %s", mtpoint);
557 			return;
558 		}
559 		if ((sfs.f_flags & MNT_RDONLY) != 0) {
560 			if (mip->mi_forced_pw) {
561 				warnx(
562 	"Not changing mode/owner of %s since it is read-only",
563 				    mtpoint);
564 			} else {
565 				debugprintf(
566 	"Not changing mode/owner of %s since it is read-only",
567 				    mtpoint);
568 			}
569 			return;
570 		}
571 	}
572 
573 	if (mip->mi_have_mode) {
574 		debugprintf("changing mode of %s to %o.", mtpoint,
575 		    mip->mi_mode);
576 		if (!norun)
577 			if (chmod(mtpoint, mip->mi_mode) == -1)
578 				err(1, "chmod: %s", mtpoint);
579 	}
580 	/*
581 	 * We have to do these separately because the user may have
582 	 * only specified one of them.
583 	 */
584 	if (mip->mi_have_uid) {
585 		debugprintf("changing owner (user) or %s to %u.", mtpoint,
586 		    mip->mi_uid);
587 		if (!norun)
588 			if (chown(mtpoint, mip->mi_uid, -1) == -1)
589 				err(1, "chown %s to %u (user)", mtpoint,
590 				    mip->mi_uid);
591 	}
592 	if (mip->mi_have_gid) {
593 		debugprintf("changing owner (group) or %s to %u.", mtpoint,
594 		    mip->mi_gid);
595 		if (!norun)
596 			if (chown(mtpoint, -1, mip->mi_gid) == -1)
597 				err(1, "chown %s to %u (group)", mtpoint,
598 				    mip->mi_gid);
599 	}
600 }
601 
602 /*
603  * Put a file system on the memory disk.
604  */
605 static void
606 do_newfs(const char *args)
607 {
608 	int rv;
609 
610 	rv = run(NULL, "%s%s /dev/%s%d", _PATH_NEWFS, args, mdname, unit);
611 	if (rv)
612 		errx(1, "newfs exited %s %d", run_exitstr(rv),
613 		    run_exitnumber(rv));
614 }
615 
616 /*
617  * 'str' should be a user and group name similar to the last argument
618  * to chown(1); i.e., a user, followed by a colon, followed by a
619  * group.  The user and group in 'str' may be either a [ug]id or a
620  * name.  Upon return, the uid and gid fields in 'mip' will contain
621  * the uid and gid of the user and group name in 'str', respectively.
622  *
623  * In other words, this derives a user and group id from a string
624  * formatted like the last argument to chown(1).
625  *
626  * Notice: At this point we don't support only a username or only a
627  * group name. do_mtptsetup already does, so when this feature is
628  * desired, this is the only routine that needs to be changed.
629  */
630 static void
631 extract_ugid(const char *str, struct mtpt_info *mip)
632 {
633 	char *ug;			/* Writable 'str'. */
634 	char *user, *group;		/* Result of extracton. */
635 	struct passwd *pw;
636 	struct group *gr;
637 	char *p;
638 	uid_t *uid;
639 	gid_t *gid;
640 
641 	uid = &mip->mi_uid;
642 	gid = &mip->mi_gid;
643 	mip->mi_have_uid = mip->mi_have_gid = false;
644 
645 	/* Extract the user and group from 'str'.  Format above. */
646 	ug = strdup(str);
647 	assert(ug != NULL);
648 	group = ug;
649 	user = strsep(&group, ":");
650 	if (user == NULL || group == NULL || *user == '\0' || *group == '\0')
651 		usage();
652 
653 	/* Derive uid. */
654 	*uid = strtoul(user, &p, 10);
655 	if (*uid == (uid_t)ULONG_MAX)
656 		usage();
657 	if (*p != '\0') {
658 		pw = getpwnam(user);
659 		if (pw == NULL)
660 			errx(1, "invalid user: %s", user);
661 		*uid = pw->pw_uid;
662 	}
663 	mip->mi_have_uid = true;
664 
665 	/* Derive gid. */
666 	*gid = strtoul(group, &p, 10);
667 	if (*gid == (gid_t)ULONG_MAX)
668 		usage();
669 	if (*p != '\0') {
670 		gr = getgrnam(group);
671 		if (gr == NULL)
672 			errx(1, "invalid group: %s", group);
673 		*gid = gr->gr_gid;
674 	}
675 	mip->mi_have_gid = true;
676 
677 	free(ug);
678 }
679 
680 /*
681  * Run a process with command name and arguments pointed to by the
682  * formatted string 'cmdline'.  Since system(3) is not used, the first
683  * space-delimited token of 'cmdline' must be the full pathname of the
684  * program to run.
685  *
686  * The return value is the return code of the process spawned, or a negative
687  * signal number if the process exited due to an uncaught signal.
688  *
689  * If 'ofd' is non-NULL, it is set to the standard output of
690  * the program spawned (i.e., you can read from ofd and get the output
691  * of the program).
692  */
693 static int
694 run(int *ofd, const char *cmdline, ...)
695 {
696 	char **argv, **argvp;		/* Result of splitting 'cmd'. */
697 	int argc;
698 	char *cmd;			/* Expansion of 'cmdline'. */
699 	int pid, status;		/* Child info. */
700 	int pfd[2];			/* Pipe to the child. */
701 	int nfd;			/* Null (/dev/null) file descriptor. */
702 	bool dup2dn;			/* Dup /dev/null to stdout? */
703 	va_list ap;
704 	char *p;
705 	int rv, i;
706 
707 	dup2dn = true;
708 	va_start(ap, cmdline);
709 	rv = vasprintf(&cmd, cmdline, ap);
710 	if (rv == -1)
711 		err(1, "vasprintf");
712 	va_end(ap);
713 
714 	/* Split up 'cmd' into 'argv' for use with execve. */
715 	for (argc = 1, p = cmd; (p = strchr(p, ' ')) != NULL; p++)
716 		argc++;		/* 'argc' generation loop. */
717 	argv = (char **)malloc(sizeof(*argv) * (argc + 1));
718 	assert(argv != NULL);
719 	for (p = cmd, argvp = argv; (*argvp = strsep(&p, " ")) != NULL;)
720 		if (**argvp != '\0')
721 			if (++argvp >= &argv[argc]) {
722 				*argvp = NULL;
723 				break;
724 			}
725 	assert(*argv);
726 	/* The argv array ends up NULL-terminated here. */
727 
728 	/* Make sure the above loop works as expected. */
729 	if (debug) {
730 		/*
731 		 * We can't, but should, use debugprintf here.  First,
732 		 * it appends a trailing newline to the output, and
733 		 * second it prepends "DEBUG: " to the output.  The
734 		 * former is a problem for this would-be first call,
735 		 * and the latter for the would-be call inside the
736 		 * loop.
737 		 */
738 		(void)fprintf(stderr, "DEBUG: running:");
739 		/* Should be equivalent to 'cmd' (before strsep, of course). */
740 		for (i = 0; argv[i] != NULL; i++)
741 			(void)fprintf(stderr, " %s", argv[i]);
742 		(void)fprintf(stderr, "\n");
743 	}
744 
745 	/* Create a pipe if necessary and fork the helper program. */
746 	if (ofd != NULL) {
747 		if (pipe(&pfd[0]) == -1)
748 			err(1, "pipe");
749 		*ofd = pfd[0];
750 		dup2dn = false;
751 	}
752 	pid = fork();
753 	switch (pid) {
754 	case 0:
755 		/* XXX can we call err() in here? */
756 		if (norun)
757 			_exit(0);
758 		if (ofd != NULL)
759 			if (dup2(pfd[1], STDOUT_FILENO) < 0)
760 				err(1, "dup2");
761 		if (!loudsubs) {
762 			nfd = open(_PATH_DEVNULL, O_RDWR);
763 			if (nfd == -1)
764 				err(1, "open: %s", _PATH_DEVNULL);
765 			if (dup2(nfd, STDIN_FILENO) < 0)
766 				err(1, "dup2");
767 			if (dup2dn)
768 				if (dup2(nfd, STDOUT_FILENO) < 0)
769 				   err(1, "dup2");
770 			if (dup2(nfd, STDERR_FILENO) < 0)
771 				err(1, "dup2");
772 		}
773 
774 		(void)execv(argv[0], argv);
775 		warn("exec: %s", argv[0]);
776 		_exit(-1);
777 	case -1:
778 		err(1, "fork");
779 	}
780 
781 	free(cmd);
782 	free(argv);
783 	while (waitpid(pid, &status, 0) != pid)
784 		;
785 	if (WIFEXITED(status))
786 		return (WEXITSTATUS(status));
787 	if (WIFSIGNALED(status))
788 		return (-WTERMSIG(status));
789 	err(1, "unexpected waitpid status: 0x%x", status);
790 }
791 
792 /*
793  * If run() returns non-zero, provide a string explaining why.
794  */
795 static const char *
796 run_exitstr(int rv)
797 {
798 	if (rv > 0)
799 		return ("with error code");
800 	if (rv < 0)
801 		return ("with signal");
802 	return (NULL);
803 }
804 
805 /*
806  * If run returns non-zero, provide a relevant number.
807  */
808 static int
809 run_exitnumber(int rv)
810 {
811 	if (rv < 0)
812 		return (-rv);
813 	return (rv);
814 }
815 
816 static void
817 usage(void)
818 {
819 
820 	fprintf(stderr,
821 "usage: %s [-DLlMNnPStUX] [-a maxcontig] [-b block-size]\n"
822 "\t[-c blocks-per-cylinder-group][-d max-extent-size] [-E path-mdconfig]\n"
823 "\t[-e maxbpg] [-F file] [-f frag-size] [-i bytes] [-m percent-free]\n"
824 "\t[-O optimization] [-o mount-options]\n"
825 "\t[-p permissions] [-s size] [-v version] [-w user:group]\n"
826 "\tmd-device mount-point\n", getprogname());
827 	exit(1);
828 }
829