xref: /freebsd/sbin/mdmfs/mdmfs.c (revision 0957b409a90fd597c1e9124cbaf3edd2b488f4ac)
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 			argappend(&mdconfig_arg, "-o reserve");
200 			break;
201 		case 'm':
202 			argappend(&newfs_arg, "-m %s", optarg);
203 			break;
204 		case 'N':
205 			norun = true;
206 			break;
207 		case 'n':
208 			argappend(&newfs_arg, "-n");
209 			break;
210 		case 'O':
211 			argappend(&newfs_arg, "-o %s", optarg);
212 			break;
213 		case 'o':
214 			argappend(&mount_arg, "-o %s", optarg);
215 			break;
216 		case 'P':
217 			newfs = false;
218 			break;
219 		case 'p':
220 			if ((set = setmode(optarg)) == NULL)
221 				usage();
222 			mi.mi_mode = getmode(set, S_IRWXU | S_IRWXG | S_IRWXO);
223 			mi.mi_have_mode = true;
224 			mi.mi_forced_pw = true;
225 			free(set);
226 			break;
227 		case 'S':
228 			softdep = false;
229 			break;
230 		case 's':
231 			size_arg = optarg;
232 			break;
233 		case 't':
234 			argappend(&newfs_arg, "-t");
235 			break;
236 		case 'T':
237 			argappend(&mount_arg, "-t %s", optarg);
238 			break;
239 		case 'U':
240 			softdep = true;
241 			break;
242 		case 'v':
243 			argappend(&newfs_arg, "-O %s", optarg);
244 			break;
245 		case 'w':
246 			extract_ugid(optarg, &mi);
247 			mi.mi_forced_pw = true;
248 			break;
249 		case 'X':
250 			debug = true;
251 			break;
252 		default:
253 			usage();
254 		}
255 	argc -= optind;
256 	argv += optind;
257 	if (argc < 2)
258 		usage();
259 
260 	/*
261 	 * Historically our size arg was passed directly to mdconfig, which
262 	 * treats a number without a suffix as a count of 512-byte sectors;
263 	 * tmpfs would treat it as a count of bytes.  To get predictable
264 	 * behavior for 'auto' we document that the size always uses mdconfig
265 	 * rules.  To make that work, decode the size here so it can be passed
266 	 * to either tmpfs or mdconfig as a count of bytes.
267 	 */
268 	if (size_arg != NULL) {
269 		mdsize = (intmax_t)strtoumax(size_arg, &p, 0);
270 		if (p == size_arg || (p[0] != 0 && p[1] != 0) || mdsize < 0)
271 			errx(1, "invalid size '%s'", size_arg);
272 		switch (*p) {
273 		case 'p':
274 		case 'P':
275 			mdsize *= 1024;
276 		case 't':
277 		case 'T':
278 			mdsize *= 1024;
279 		case 'g':
280 		case 'G':
281 			mdsize *= 1024;
282 		case 'm':
283 		case 'M':
284 			mdsize *= 1024;
285 		case 'k':
286 		case 'K':
287 			mdsize *= 1024;
288 		case 'b':
289 		case 'B':
290 			break;
291 		case '\0':
292 			mdsize *= 512;
293 			break;
294 		default:
295 			errx(1, "invalid size suffix on '%s'", size_arg);
296 		}
297 	}
298 
299 	/*
300 	 * Based on the command line 'md-device' either mount a tmpfs filesystem
301 	 * or configure the md device then format and mount a filesystem on it.
302 	 * If the device is 'auto' use tmpfs if it is available and there is no
303 	 * request for multilabel MAC (which tmpfs does not support).
304 	 */
305 	unitstr = argv[0];
306 	mtpoint = argv[1];
307 
308 	if (strcmp(unitstr, "auto") == 0) {
309 		if (mlmac)
310 			idx = -1; /* Must use md for mlmac. */
311 		else if ((idx = modfind("tmpfs")) == -1)
312 			idx = kldload("tmpfs");
313 		if (idx == -1)
314 			unitstr = "md";
315 		else
316 			unitstr = "tmpfs";
317 	}
318 
319 	if (strcmp(unitstr, "tmpfs") == 0) {
320 		if (size_arg != NULL && mdsize != 0)
321 			argappend(&mount_arg, "-o size=%jd", mdsize);
322 		do_mount_tmpfs(mount_arg, mtpoint);
323 	} else {
324 		if (size_arg != NULL)
325 			argappend(&mdconfig_arg, "-s %jdB", mdsize);
326 		if (strncmp(unitstr, "/dev/", 5) == 0)
327 			unitstr += 5;
328 		if (strncmp(unitstr, mdname, mdnamelen) == 0)
329 			unitstr += mdnamelen;
330 		if (!isdigit(*unitstr)) {
331 			autounit = true;
332 			unit = -1;
333 			mdsuffix = unitstr;
334 		} else {
335 			ul = strtoul(unitstr, &p, 10);
336 			if (ul == ULONG_MAX)
337 				errx(1, "bad device unit: %s", unitstr);
338 			unit = ul;
339 			mdsuffix = p;	/* can be empty */
340 		}
341 
342 		if (!have_mdtype)
343 			mdtype = MD_SWAP;
344 		if (softdep)
345 			argappend(&newfs_arg, "-U");
346 		if (mdtype != MD_VNODE && !newfs)
347 			errx(1, "-P requires a vnode-backed disk");
348 
349 		/* Do the work. */
350 		if (detach && !autounit)
351 			do_mdconfig_detach();
352 		if (autounit)
353 			do_mdconfig_attach_au(mdconfig_arg, mdtype);
354 		else
355 			do_mdconfig_attach(mdconfig_arg, mdtype);
356 		if (newfs)
357 			do_newfs(newfs_arg);
358 		do_mount_md(mount_arg, mtpoint);
359 	}
360 
361 	do_mtptsetup(mtpoint, &mi);
362 
363 	return (0);
364 }
365 
366 /*
367  * Append the expansion of 'fmt' to the buffer pointed to by '*dstp';
368  * reallocate as required.
369  */
370 static void
371 argappend(char **dstp, const char *fmt, ...)
372 {
373 	char *old, *new;
374 	va_list ap;
375 
376 	old = *dstp;
377 	assert(old != NULL);
378 
379 	va_start(ap, fmt);
380 	if (vasprintf(&new, fmt,ap) == -1)
381 		errx(1, "vasprintf");
382 	va_end(ap);
383 
384 	*dstp = new;
385 	if (asprintf(&new, "%s %s", old, new) == -1)
386 		errx(1, "asprintf");
387 	free(*dstp);
388 	free(old);
389 
390 	*dstp = new;
391 }
392 
393 /*
394  * If run-time debugging is enabled, print the expansion of 'fmt'.
395  * Otherwise, do nothing.
396  */
397 static void
398 debugprintf(const char *fmt, ...)
399 {
400 	va_list ap;
401 
402 	if (!debug)
403 		return;
404 	fprintf(stderr, "DEBUG: ");
405 	va_start(ap, fmt);
406 	vfprintf(stderr, fmt, ap);
407 	va_end(ap);
408 	fprintf(stderr, "\n");
409 	fflush(stderr);
410 }
411 
412 /*
413  * Attach a memory disk with a known unit.
414  */
415 static void
416 do_mdconfig_attach(const char *args, const enum md_types mdtype)
417 {
418 	int rv;
419 	const char *ta;		/* Type arg. */
420 
421 	switch (mdtype) {
422 	case MD_SWAP:
423 		ta = "-t swap";
424 		break;
425 	case MD_VNODE:
426 		ta = "-t vnode";
427 		break;
428 	case MD_MALLOC:
429 		ta = "-t malloc";
430 		break;
431 	default:
432 		abort();
433 	}
434 	rv = run(NULL, "%s -a %s%s -u %s%d", path_mdconfig, ta, args,
435 	    mdname, unit);
436 	if (rv)
437 		errx(1, "mdconfig (attach) exited %s %d", run_exitstr(rv),
438 		    run_exitnumber(rv));
439 }
440 
441 /*
442  * Attach a memory disk with an unknown unit; use autounit.
443  */
444 static void
445 do_mdconfig_attach_au(const char *args, const enum md_types mdtype)
446 {
447 	const char *ta;		/* Type arg. */
448 	char *linep;
449 	char linebuf[12];	/* 32-bit unit (10) + '\n' (1) + '\0' (1) */
450 	int fd;			/* Standard output of mdconfig invocation. */
451 	FILE *sfd;
452 	int rv;
453 	char *p;
454 	size_t linelen;
455 	unsigned long ul;
456 
457 	switch (mdtype) {
458 	case MD_SWAP:
459 		ta = "-t swap";
460 		break;
461 	case MD_VNODE:
462 		ta = "-t vnode";
463 		break;
464 	case MD_MALLOC:
465 		ta = "-t malloc";
466 		break;
467 	default:
468 		abort();
469 	}
470 	rv = run(&fd, "%s -a %s%s", path_mdconfig, ta, args);
471 	if (rv)
472 		errx(1, "mdconfig (attach) exited %s %d", run_exitstr(rv),
473 		    run_exitnumber(rv));
474 
475 	/* Receive the unit number. */
476 	if (norun) {	/* Since we didn't run, we can't read.  Fake it. */
477 		unit = 0;
478 		return;
479 	}
480 	sfd = fdopen(fd, "r");
481 	if (sfd == NULL)
482 		err(1, "fdopen");
483 	linep = fgetln(sfd, &linelen);
484 	/* If the output format changes, we want to know about it. */
485 	if (linep == NULL || linelen <= mdnamelen + 1 ||
486 	    linelen - mdnamelen >= sizeof(linebuf) ||
487 	    strncmp(linep, mdname, mdnamelen) != 0)
488 		errx(1, "unexpected output from mdconfig (attach)");
489 	linep += mdnamelen;
490 	linelen -= mdnamelen;
491 	/* Can't use strlcpy because linep is not NULL-terminated. */
492 	strncpy(linebuf, linep, linelen);
493 	linebuf[linelen] = '\0';
494 	ul = strtoul(linebuf, &p, 10);
495 	if (ul == ULONG_MAX || *p != '\n')
496 		errx(1, "unexpected output from mdconfig (attach)");
497 	unit = ul;
498 
499 	fclose(sfd);
500 }
501 
502 /*
503  * Detach a memory disk.
504  */
505 static void
506 do_mdconfig_detach(void)
507 {
508 	int rv;
509 
510 	rv = run(NULL, "%s -d -u %s%d", path_mdconfig, mdname, unit);
511 	if (rv && debug)	/* This is allowed to fail. */
512 		warnx("mdconfig (detach) exited %s %d (ignored)",
513 		    run_exitstr(rv), run_exitnumber(rv));
514 }
515 
516 /*
517  * Mount the configured memory disk.
518  */
519 static void
520 do_mount_md(const char *args, const char *mtpoint)
521 {
522 	int rv;
523 
524 	rv = run(NULL, "%s%s /dev/%s%d%s %s", _PATH_MOUNT, args,
525 	    mdname, unit, mdsuffix, mtpoint);
526 	if (rv)
527 		errx(1, "mount exited %s %d", run_exitstr(rv),
528 		    run_exitnumber(rv));
529 }
530 
531 /*
532  * Mount the configured tmpfs.
533  */
534 static void
535 do_mount_tmpfs(const char *args, const char *mtpoint)
536 {
537 	int rv;
538 
539 	rv = run(NULL, "%s -t tmpfs %s tmp %s", _PATH_MOUNT, args, mtpoint);
540 	if (rv)
541 		errx(1, "tmpfs mount exited %s %d", run_exitstr(rv),
542 		    run_exitnumber(rv));
543 }
544 
545 /*
546  * Various configuration of the mountpoint.  Mostly, enact 'mip'.
547  */
548 static void
549 do_mtptsetup(const char *mtpoint, struct mtpt_info *mip)
550 {
551 	struct statfs sfs;
552 
553 	if (!mip->mi_have_mode && !mip->mi_have_uid && !mip->mi_have_gid)
554 		return;
555 
556 	if (!norun) {
557 		if (statfs(mtpoint, &sfs) == -1) {
558 			warn("statfs: %s", mtpoint);
559 			return;
560 		}
561 		if ((sfs.f_flags & MNT_RDONLY) != 0) {
562 			if (mip->mi_forced_pw) {
563 				warnx(
564 	"Not changing mode/owner of %s since it is read-only",
565 				    mtpoint);
566 			} else {
567 				debugprintf(
568 	"Not changing mode/owner of %s since it is read-only",
569 				    mtpoint);
570 			}
571 			return;
572 		}
573 	}
574 
575 	if (mip->mi_have_mode) {
576 		debugprintf("changing mode of %s to %o.", mtpoint,
577 		    mip->mi_mode);
578 		if (!norun)
579 			if (chmod(mtpoint, mip->mi_mode) == -1)
580 				err(1, "chmod: %s", mtpoint);
581 	}
582 	/*
583 	 * We have to do these separately because the user may have
584 	 * only specified one of them.
585 	 */
586 	if (mip->mi_have_uid) {
587 		debugprintf("changing owner (user) or %s to %u.", mtpoint,
588 		    mip->mi_uid);
589 		if (!norun)
590 			if (chown(mtpoint, mip->mi_uid, -1) == -1)
591 				err(1, "chown %s to %u (user)", mtpoint,
592 				    mip->mi_uid);
593 	}
594 	if (mip->mi_have_gid) {
595 		debugprintf("changing owner (group) or %s to %u.", mtpoint,
596 		    mip->mi_gid);
597 		if (!norun)
598 			if (chown(mtpoint, -1, mip->mi_gid) == -1)
599 				err(1, "chown %s to %u (group)", mtpoint,
600 				    mip->mi_gid);
601 	}
602 }
603 
604 /*
605  * Put a file system on the memory disk.
606  */
607 static void
608 do_newfs(const char *args)
609 {
610 	int rv;
611 
612 	rv = run(NULL, "%s%s /dev/%s%d", _PATH_NEWFS, args, mdname, unit);
613 	if (rv)
614 		errx(1, "newfs exited %s %d", run_exitstr(rv),
615 		    run_exitnumber(rv));
616 }
617 
618 /*
619  * 'str' should be a user and group name similar to the last argument
620  * to chown(1); i.e., a user, followed by a colon, followed by a
621  * group.  The user and group in 'str' may be either a [ug]id or a
622  * name.  Upon return, the uid and gid fields in 'mip' will contain
623  * the uid and gid of the user and group name in 'str', respectively.
624  *
625  * In other words, this derives a user and group id from a string
626  * formatted like the last argument to chown(1).
627  *
628  * Notice: At this point we don't support only a username or only a
629  * group name. do_mtptsetup already does, so when this feature is
630  * desired, this is the only routine that needs to be changed.
631  */
632 static void
633 extract_ugid(const char *str, struct mtpt_info *mip)
634 {
635 	char *ug;			/* Writable 'str'. */
636 	char *user, *group;		/* Result of extracton. */
637 	struct passwd *pw;
638 	struct group *gr;
639 	char *p;
640 	uid_t *uid;
641 	gid_t *gid;
642 
643 	uid = &mip->mi_uid;
644 	gid = &mip->mi_gid;
645 	mip->mi_have_uid = mip->mi_have_gid = false;
646 
647 	/* Extract the user and group from 'str'.  Format above. */
648 	ug = strdup(str);
649 	assert(ug != NULL);
650 	group = ug;
651 	user = strsep(&group, ":");
652 	if (user == NULL || group == NULL || *user == '\0' || *group == '\0')
653 		usage();
654 
655 	/* Derive uid. */
656 	*uid = strtoul(user, &p, 10);
657 	if (*uid == (uid_t)ULONG_MAX)
658 		usage();
659 	if (*p != '\0') {
660 		pw = getpwnam(user);
661 		if (pw == NULL)
662 			errx(1, "invalid user: %s", user);
663 		*uid = pw->pw_uid;
664 	}
665 	mip->mi_have_uid = true;
666 
667 	/* Derive gid. */
668 	*gid = strtoul(group, &p, 10);
669 	if (*gid == (gid_t)ULONG_MAX)
670 		usage();
671 	if (*p != '\0') {
672 		gr = getgrnam(group);
673 		if (gr == NULL)
674 			errx(1, "invalid group: %s", group);
675 		*gid = gr->gr_gid;
676 	}
677 	mip->mi_have_gid = true;
678 
679 	free(ug);
680 }
681 
682 /*
683  * Run a process with command name and arguments pointed to by the
684  * formatted string 'cmdline'.  Since system(3) is not used, the first
685  * space-delimited token of 'cmdline' must be the full pathname of the
686  * program to run.
687  *
688  * The return value is the return code of the process spawned, or a negative
689  * signal number if the process exited due to an uncaught signal.
690  *
691  * If 'ofd' is non-NULL, it is set to the standard output of
692  * the program spawned (i.e., you can read from ofd and get the output
693  * of the program).
694  */
695 static int
696 run(int *ofd, const char *cmdline, ...)
697 {
698 	char **argv, **argvp;		/* Result of splitting 'cmd'. */
699 	int argc;
700 	char *cmd;			/* Expansion of 'cmdline'. */
701 	int pid, status;		/* Child info. */
702 	int pfd[2];			/* Pipe to the child. */
703 	int nfd;			/* Null (/dev/null) file descriptor. */
704 	bool dup2dn;			/* Dup /dev/null to stdout? */
705 	va_list ap;
706 	char *p;
707 	int rv, i;
708 
709 	dup2dn = true;
710 	va_start(ap, cmdline);
711 	rv = vasprintf(&cmd, cmdline, ap);
712 	if (rv == -1)
713 		err(1, "vasprintf");
714 	va_end(ap);
715 
716 	/* Split up 'cmd' into 'argv' for use with execve. */
717 	for (argc = 1, p = cmd; (p = strchr(p, ' ')) != NULL; p++)
718 		argc++;		/* 'argc' generation loop. */
719 	argv = (char **)malloc(sizeof(*argv) * (argc + 1));
720 	assert(argv != NULL);
721 	for (p = cmd, argvp = argv; (*argvp = strsep(&p, " ")) != NULL;)
722 		if (**argvp != '\0')
723 			if (++argvp >= &argv[argc]) {
724 				*argvp = NULL;
725 				break;
726 			}
727 	assert(*argv);
728 	/* The argv array ends up NULL-terminated here. */
729 
730 	/* Make sure the above loop works as expected. */
731 	if (debug) {
732 		/*
733 		 * We can't, but should, use debugprintf here.  First,
734 		 * it appends a trailing newline to the output, and
735 		 * second it prepends "DEBUG: " to the output.  The
736 		 * former is a problem for this would-be first call,
737 		 * and the latter for the would-be call inside the
738 		 * loop.
739 		 */
740 		(void)fprintf(stderr, "DEBUG: running:");
741 		/* Should be equivalent to 'cmd' (before strsep, of course). */
742 		for (i = 0; argv[i] != NULL; i++)
743 			(void)fprintf(stderr, " %s", argv[i]);
744 		(void)fprintf(stderr, "\n");
745 	}
746 
747 	/* Create a pipe if necessary and fork the helper program. */
748 	if (ofd != NULL) {
749 		if (pipe(&pfd[0]) == -1)
750 			err(1, "pipe");
751 		*ofd = pfd[0];
752 		dup2dn = false;
753 	}
754 	pid = fork();
755 	switch (pid) {
756 	case 0:
757 		/* XXX can we call err() in here? */
758 		if (norun)
759 			_exit(0);
760 		if (ofd != NULL)
761 			if (dup2(pfd[1], STDOUT_FILENO) < 0)
762 				err(1, "dup2");
763 		if (!loudsubs) {
764 			nfd = open(_PATH_DEVNULL, O_RDWR);
765 			if (nfd == -1)
766 				err(1, "open: %s", _PATH_DEVNULL);
767 			if (dup2(nfd, STDIN_FILENO) < 0)
768 				err(1, "dup2");
769 			if (dup2dn)
770 				if (dup2(nfd, STDOUT_FILENO) < 0)
771 				   err(1, "dup2");
772 			if (dup2(nfd, STDERR_FILENO) < 0)
773 				err(1, "dup2");
774 		}
775 
776 		(void)execv(argv[0], argv);
777 		warn("exec: %s", argv[0]);
778 		_exit(-1);
779 	case -1:
780 		err(1, "fork");
781 	}
782 
783 	free(cmd);
784 	free(argv);
785 	while (waitpid(pid, &status, 0) != pid)
786 		;
787 	if (WIFEXITED(status))
788 		return (WEXITSTATUS(status));
789 	if (WIFSIGNALED(status))
790 		return (-WTERMSIG(status));
791 	err(1, "unexpected waitpid status: 0x%x", status);
792 }
793 
794 /*
795  * If run() returns non-zero, provide a string explaining why.
796  */
797 static const char *
798 run_exitstr(int rv)
799 {
800 	if (rv > 0)
801 		return ("with error code");
802 	if (rv < 0)
803 		return ("with signal");
804 	return (NULL);
805 }
806 
807 /*
808  * If run returns non-zero, provide a relevant number.
809  */
810 static int
811 run_exitnumber(int rv)
812 {
813 	if (rv < 0)
814 		return (-rv);
815 	return (rv);
816 }
817 
818 static void
819 usage(void)
820 {
821 
822 	fprintf(stderr,
823 "usage: %s [-DLlMNnPStUX] [-a maxcontig] [-b block-size]\n"
824 "\t[-c blocks-per-cylinder-group][-d max-extent-size] [-E path-mdconfig]\n"
825 "\t[-e maxbpg] [-F file] [-f frag-size] [-i bytes] [-m percent-free]\n"
826 "\t[-O optimization] [-o mount-options]\n"
827 "\t[-p permissions] [-s size] [-v version] [-w user:group]\n"
828 "\tmd-device mount-point\n", getprogname());
829 	exit(1);
830 }
831