xref: /freebsd/bin/df/df.c (revision bdcbfde31e8e9b343f113a1956384bdf30d1ed62)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1980, 1990, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  * (c) UNIX System Laboratories, Inc.
7  * All or some portions of this file are derived from material licensed
8  * to the University of California by American Telephone and Telegraph
9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10  * the permission of UNIX System Laboratories, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #if 0
38 #ifndef lint
39 static const char copyright[] =
40 "@(#) Copyright (c) 1980, 1990, 1993, 1994\n\
41 	The Regents of the University of California.  All rights reserved.\n";
42 #endif /* not lint */
43 
44 #endif
45 #include <sys/cdefs.h>
46 #include <sys/param.h>
47 #include <sys/stat.h>
48 #include <sys/mount.h>
49 #include <sys/sysctl.h>
50 #include <getopt.h>
51 #include <libutil.h>
52 #include <locale.h>
53 #include <stdint.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <sysexits.h>
58 #include <unistd.h>
59 #include <libxo/xo.h>
60 
61 #define UNITS_SI	1
62 #define UNITS_2		2
63 
64 /* Maximum widths of various fields. */
65 struct maxwidths {
66 	int	mntfrom;
67 	int	fstype;
68 	int	total;
69 	int	used;
70 	int	avail;
71 	int	iused;
72 	int	ifree;
73 };
74 
75 static void	  addstat(struct statfs *, struct statfs *);
76 static char	 *getmntpt(const char *);
77 static const char **makevfslist(char *fslist, int *skip);
78 static int	  checkvfsname(const char *vfsname, const char **vfslist, int skip);
79 static int	  checkvfsselected(char *);
80 static int	  int64width(int64_t);
81 static char	 *makenetvfslist(void);
82 static void	  prthuman(const struct statfs *, int64_t);
83 static void	  prthumanval(const char *, int64_t);
84 static intmax_t	  fsbtoblk(int64_t, uint64_t, u_long);
85 static void	  prtstat(struct statfs *, struct maxwidths *);
86 static size_t	  regetmntinfo(struct statfs **, long);
87 static void	  update_maxwidths(struct maxwidths *, const struct statfs *);
88 static void	  usage(void);
89 
90 static __inline int
91 imax(int a, int b)
92 {
93 	return (a > b ? a : b);
94 }
95 
96 static int	  aflag = 0, cflag, hflag, iflag, kflag, lflag = 0, nflag, Tflag;
97 static int	  thousands;
98 static int	  skipvfs_l, skipvfs_t;
99 static const char **vfslist_l, **vfslist_t;
100 
101 static const struct option long_options[] =
102 {
103 	{ "si", no_argument, NULL, 'H' },
104 	{ NULL, no_argument, NULL, 0 },
105 };
106 
107 int
108 main(int argc, char *argv[])
109 {
110 	struct stat stbuf;
111 	struct statfs statfsbuf, totalbuf;
112 	struct maxwidths maxwidths;
113 	struct statfs *mntbuf;
114 	char *mntpt;
115 	int i, mntsize;
116 	int ch, rv;
117 
118 	(void)setlocale(LC_ALL, "");
119 	memset(&maxwidths, 0, sizeof(maxwidths));
120 	memset(&totalbuf, 0, sizeof(totalbuf));
121 	totalbuf.f_bsize = DEV_BSIZE;
122 	strlcpy(totalbuf.f_mntfromname, "total", MNAMELEN);
123 
124 	argc = xo_parse_args(argc, argv);
125 	if (argc < 0)
126 		exit(1);
127 
128 	while ((ch = getopt_long(argc, argv, "+abcgHhiklmnPt:T,", long_options,
129 	    NULL)) != -1)
130 		switch (ch) {
131 		case 'a':
132 			aflag = 1;
133 			break;
134 		case 'b':
135 				/* FALLTHROUGH */
136 		case 'P':
137 			/*
138 			 * POSIX specifically discusses the behavior of
139 			 * both -k and -P. It states that the blocksize should
140 			 * be set to 1024. Thus, if this occurs, simply break
141 			 * rather than clobbering the old blocksize.
142 			 */
143 			if (kflag)
144 				break;
145 			setenv("BLOCKSIZE", "512", 1);
146 			hflag = 0;
147 			break;
148 		case 'c':
149 			cflag = 1;
150 			break;
151 		case 'g':
152 			setenv("BLOCKSIZE", "1g", 1);
153 			hflag = 0;
154 			break;
155 		case 'H':
156 			hflag = UNITS_SI;
157 			break;
158 		case 'h':
159 			hflag = UNITS_2;
160 			break;
161 		case 'i':
162 			iflag = 1;
163 			break;
164 		case 'k':
165 			kflag++;
166 			setenv("BLOCKSIZE", "1024", 1);
167 			hflag = 0;
168 			break;
169 		case 'l':
170 			/* Ignore duplicate -l */
171 			if (lflag)
172 				break;
173 			vfslist_l = makevfslist(makenetvfslist(), &skipvfs_l);
174 			lflag = 1;
175 			break;
176 		case 'm':
177 			setenv("BLOCKSIZE", "1m", 1);
178 			hflag = 0;
179 			break;
180 		case 'n':
181 			nflag = 1;
182 			break;
183 		case 't':
184 			if (vfslist_t != NULL)
185 				xo_errx(1, "only one -t option may be specified");
186 			vfslist_t = makevfslist(optarg, &skipvfs_t);
187 			break;
188 		case 'T':
189 			Tflag = 1;
190 			break;
191 		case ',':
192 			thousands = 1;
193 			break;
194 		case '?':
195 		default:
196 			usage();
197 		}
198 	argc -= optind;
199 	argv += optind;
200 
201 	rv = EXIT_SUCCESS;
202 	if (!*argv) {
203 		/* everything (modulo -t) */
204 		mntsize = getmntinfo(&mntbuf, MNT_NOWAIT);
205 		mntsize = regetmntinfo(&mntbuf, mntsize);
206 	} else {
207 		/* just the filesystems specified on the command line */
208 		mntbuf = malloc(argc * sizeof(*mntbuf));
209 		if (mntbuf == NULL)
210 			xo_err(1, "malloc()");
211 		mntsize = 0;
212 		/* continued in for loop below */
213 	}
214 
215 	xo_open_container("storage-system-information");
216 	xo_open_list("filesystem");
217 
218 	/* iterate through specified filesystems */
219 	for (; *argv; argv++) {
220 		if (stat(*argv, &stbuf) < 0) {
221 			if ((mntpt = getmntpt(*argv)) == NULL) {
222 				xo_warn("%s", *argv);
223 				rv = EXIT_FAILURE;
224 				continue;
225 			}
226 		} else if (S_ISCHR(stbuf.st_mode)) {
227 			mntpt = getmntpt(*argv);
228 			if (mntpt == NULL) {
229 				xo_warnx("%s: not mounted", *argv);
230 				rv = EXIT_FAILURE;
231 				continue;
232 			}
233 		} else {
234 			mntpt = *argv;
235 		}
236 
237 		/*
238 		 * Statfs does not take a `wait' flag, so we cannot
239 		 * implement nflag here.
240 		 */
241 		if (statfs(mntpt, &statfsbuf) < 0) {
242 			xo_warn("%s", mntpt);
243 			rv = EXIT_FAILURE;
244 			continue;
245 		}
246 
247 		/*
248 		 * Check to make sure the arguments we've been given are
249 		 * satisfied.  Return an error if we have been asked to
250 		 * list a mount point that does not match the other args
251 		 * we've been given (-l, -t, etc.).
252 		 */
253 		if (checkvfsselected(statfsbuf.f_fstypename) != 0) {
254 			rv = EXIT_FAILURE;
255 			continue;
256 		}
257 
258 		/* the user asked for it, so ignore the ignore flag */
259 		statfsbuf.f_flags &= ~MNT_IGNORE;
260 
261 		/* add to list */
262 		mntbuf[mntsize++] = statfsbuf;
263 	}
264 
265 	memset(&maxwidths, 0, sizeof(maxwidths));
266 	for (i = 0; i < mntsize; i++) {
267 		if (aflag || (mntbuf[i].f_flags & MNT_IGNORE) == 0) {
268 			update_maxwidths(&maxwidths, &mntbuf[i]);
269 			if (cflag)
270 				addstat(&totalbuf, &mntbuf[i]);
271 		}
272 	}
273 	for (i = 0; i < mntsize; i++)
274 		if (aflag || (mntbuf[i].f_flags & MNT_IGNORE) == 0)
275 			prtstat(&mntbuf[i], &maxwidths);
276 
277 	xo_close_list("filesystem");
278 
279 	if (cflag)
280 		prtstat(&totalbuf, &maxwidths);
281 
282 	xo_close_container("storage-system-information");
283 	if (xo_finish() < 0)
284 		rv = EXIT_FAILURE;
285 	exit(rv);
286 }
287 
288 static char *
289 getmntpt(const char *name)
290 {
291 	size_t mntsize, i;
292 	struct statfs *mntbuf;
293 
294 	mntsize = getmntinfo(&mntbuf, MNT_NOWAIT);
295 	for (i = 0; i < mntsize; i++) {
296 		if (!strcmp(mntbuf[i].f_mntfromname, name))
297 			return (mntbuf[i].f_mntonname);
298 	}
299 	return (NULL);
300 }
301 
302 static const char **
303 makevfslist(char *fslist, int *skip)
304 {
305 	const char **av;
306 	int i;
307 	char *nextcp;
308 
309 	if (fslist == NULL)
310 		return (NULL);
311 	*skip = 0;
312 	if (fslist[0] == 'n' && fslist[1] == 'o') {
313 		fslist += 2;
314 		*skip = 1;
315 	}
316 	for (i = 0, nextcp = fslist; *nextcp; nextcp++)
317 		if (*nextcp == ',')
318 			i++;
319 	if ((av = malloc((size_t)(i + 2) * sizeof(char *))) == NULL) {
320 		xo_warnx("malloc failed");
321 		return (NULL);
322 	}
323 	nextcp = fslist;
324 	i = 0;
325 	av[i++] = nextcp;
326 	while ((nextcp = strchr(nextcp, ',')) != NULL) {
327 		*nextcp++ = '\0';
328 		av[i++] = nextcp;
329 	}
330 	av[i++] = NULL;
331 	return (av);
332 }
333 
334 static int
335 checkvfsname(const char *vfsname, const char **vfslist, int skip)
336 {
337 
338 	if (vfslist == NULL)
339 		return (0);
340 	while (*vfslist != NULL) {
341 		if (strcmp(vfsname, *vfslist) == 0)
342 			return (skip);
343 		++vfslist;
344 	}
345 	return (!skip);
346 }
347 
348 /*
349  * Without -l and -t option, all file system types are enabled.
350  * The -l option selects the local file systems, if present.
351  * A -t option modifies the selection by adding or removing further
352  * file system types, based on the argument that is passed.
353  */
354 static int
355 checkvfsselected(char *fstypename)
356 {
357 	int result;
358 
359 	if (vfslist_t) {
360 		/* if -t option used then select passed types */
361 		result = checkvfsname(fstypename, vfslist_t, skipvfs_t);
362 		if (vfslist_l) {
363 			/* if -l option then adjust selection */
364 			if (checkvfsname(fstypename, vfslist_l, skipvfs_l) == skipvfs_t)
365 				result = skipvfs_t;
366 		}
367 	} else {
368 		/* no -t option then -l decides */
369 		result = checkvfsname(fstypename, vfslist_l, skipvfs_l);
370 	}
371 	return (result);
372 }
373 
374 /*
375  * Make a pass over the file system info in ``mntbuf'' filtering out
376  * file system types not in vfslist_{l,t} and possibly re-stating to get
377  * current (not cached) info.  Returns the new count of valid statfs bufs.
378  */
379 static size_t
380 regetmntinfo(struct statfs **mntbufp, long mntsize)
381 {
382 	int error, i, j;
383 	struct statfs *mntbuf;
384 
385 	if (vfslist_l == NULL && vfslist_t == NULL)
386 		return (nflag ? mntsize : getmntinfo(mntbufp, MNT_WAIT));
387 
388 	mntbuf = *mntbufp;
389 	for (j = 0, i = 0; i < mntsize; i++) {
390 		if (checkvfsselected(mntbuf[i].f_fstypename) != 0)
391 			continue;
392 		/*
393 		 * XXX statfs(2) can fail for various reasons. It may be
394 		 * possible that the user does not have access to the
395 		 * pathname, if this happens, we will fall back on
396 		 * "stale" filesystem statistics.
397 		 */
398 		error = statfs(mntbuf[i].f_mntonname, &mntbuf[j]);
399 		if (nflag || error < 0)
400 			if (i != j) {
401 				if (error < 0)
402 					xo_warnx("%s stats possibly stale",
403 					    mntbuf[i].f_mntonname);
404 				mntbuf[j] = mntbuf[i];
405 			}
406 		j++;
407 	}
408 	return (j);
409 }
410 
411 static void
412 prthuman(const struct statfs *sfsp, int64_t used)
413 {
414 
415 	prthumanval("  {:blocks/%6s}", sfsp->f_blocks * sfsp->f_bsize);
416 	prthumanval("  {:used/%6s}", used * sfsp->f_bsize);
417 	prthumanval("  {:available/%6s}", sfsp->f_bavail * sfsp->f_bsize);
418 }
419 
420 static void
421 prthumanval(const char *fmt, int64_t bytes)
422 {
423 	char buf[6];
424 	int flags;
425 
426 	flags = HN_B | HN_NOSPACE | HN_DECIMAL;
427 	if (hflag == UNITS_SI)
428 		flags |= HN_DIVISOR_1000;
429 
430 	humanize_number(buf, sizeof(buf) - (bytes < 0 ? 0 : 1),
431 	    bytes, "", HN_AUTOSCALE, flags);
432 
433 	xo_attr("value", "%lld", (long long) bytes);
434 	xo_emit(fmt, buf);
435 }
436 
437 /*
438  * Print an inode count in "human-readable" format.
439  */
440 static void
441 prthumanvalinode(const char *fmt, int64_t bytes)
442 {
443 	char buf[6];
444 	int flags;
445 
446 	flags = HN_NOSPACE | HN_DECIMAL | HN_DIVISOR_1000;
447 
448 	humanize_number(buf, sizeof(buf) - (bytes < 0 ? 0 : 1),
449 	    bytes, "", HN_AUTOSCALE, flags);
450 
451 	xo_attr("value", "%lld", (long long) bytes);
452 	xo_emit(fmt, buf);
453 }
454 
455 /*
456  * Convert statfs returned file system size into BLOCKSIZE units.
457  */
458 static intmax_t
459 fsbtoblk(int64_t num, uint64_t fsbs, u_long bs)
460 {
461 	return (num * (intmax_t) fsbs / (int64_t) bs);
462 }
463 
464 /*
465  * Print out status about a file system.
466  */
467 static void
468 prtstat(struct statfs *sfsp, struct maxwidths *mwp)
469 {
470 	static long blocksize;
471 	static int headerlen, timesthrough = 0;
472 	static const char *header;
473 	int64_t used, availblks, inodes;
474 	const char *format;
475 
476 	if (++timesthrough == 1) {
477 		mwp->mntfrom = imax(mwp->mntfrom, (int)strlen("Filesystem"));
478 		mwp->fstype = imax(mwp->fstype, (int)strlen("Type"));
479 		if (thousands) {		/* make space for commas */
480 		    mwp->total += (mwp->total - 1) / 3;
481 		    mwp->used  += (mwp->used - 1) / 3;
482 		    mwp->avail += (mwp->avail - 1) / 3;
483 		    mwp->iused += (mwp->iused - 1) / 3;
484 		    mwp->ifree += (mwp->ifree - 1) / 3;
485 		}
486 		if (hflag) {
487 			header = "   Size";
488 			mwp->total = mwp->used = mwp->avail =
489 			    (int)strlen(header);
490 		} else {
491 			header = getbsize(&headerlen, &blocksize);
492 			mwp->total = imax(mwp->total, headerlen);
493 		}
494 		mwp->used = imax(mwp->used, (int)strlen("Used"));
495 		mwp->avail = imax(mwp->avail, (int)strlen("Avail"));
496 
497 		xo_emit("{T:/%-*s}", mwp->mntfrom, "Filesystem");
498 		if (Tflag)
499 			xo_emit("  {T:/%-*s}", mwp->fstype, "Type");
500 		xo_emit(" {T:/%*s} {T:/%*s} {T:/%*s} {T:Capacity}",
501 			mwp->total, header,
502 			mwp->used, "Used", mwp->avail, "Avail");
503 		if (iflag) {
504 			mwp->iused = imax(hflag ? 0 : mwp->iused,
505 			    (int)strlen("  iused"));
506 			mwp->ifree = imax(hflag ? 0 : mwp->ifree,
507 			    (int)strlen("ifree"));
508 			xo_emit(" {T:/%*s} {T:/%*s} {T:\%iused}",
509 			    mwp->iused - 2, "iused", mwp->ifree, "ifree");
510 		}
511 		xo_emit("  {T:Mounted on}\n");
512 	}
513 
514 	xo_open_instance("filesystem");
515 	/* Check for 0 block size.  Can this happen? */
516 	if (sfsp->f_bsize == 0) {
517 		xo_warnx ("File system %s does not have a block size, assuming 512.",
518 		    sfsp->f_mntonname);
519 		sfsp->f_bsize = 512;
520 	}
521 	xo_emit("{tk:name/%-*s}", mwp->mntfrom, sfsp->f_mntfromname);
522 	if (Tflag)
523 		xo_emit("  {:type/%-*s}", mwp->fstype, sfsp->f_fstypename);
524 	used = sfsp->f_blocks - sfsp->f_bfree;
525 	availblks = sfsp->f_bavail + used;
526 	if (hflag) {
527 		prthuman(sfsp, used);
528 	} else {
529 		if (thousands)
530 		    format = " {t:total-blocks/%*j'd} {t:used-blocks/%*j'd} "
531 			"{t:available-blocks/%*j'd}";
532 		else
533 		    format = " {t:total-blocks/%*jd} {t:used-blocks/%*jd} "
534 			"{t:available-blocks/%*jd}";
535 		xo_emit(format,
536 		    mwp->total, fsbtoblk(sfsp->f_blocks,
537 		    sfsp->f_bsize, blocksize),
538 		    mwp->used, fsbtoblk(used, sfsp->f_bsize, blocksize),
539 		    mwp->avail, fsbtoblk(sfsp->f_bavail,
540 		    sfsp->f_bsize, blocksize));
541 	}
542 	xo_emit(" {:used-percent/%5.0f}{U:%%}",
543 	    availblks == 0 ? 100.0 : (double)used / (double)availblks * 100.0);
544 	if (iflag) {
545 		inodes = sfsp->f_files;
546 		used = inodes - sfsp->f_ffree;
547 		if (hflag) {
548 			xo_emit("  ");
549 			prthumanvalinode(" {:inodes-used/%5s}", used);
550 			prthumanvalinode(" {:inodes-free/%5s}", sfsp->f_ffree);
551 		} else {
552 			if (thousands)
553 			    format = " {:inodes-used/%*j'd} {:inodes-free/%*j'd}";
554 			else
555 			    format = " {:inodes-used/%*jd} {:inodes-free/%*jd}";
556 			xo_emit(format, mwp->iused, (intmax_t)used,
557 			    mwp->ifree, (intmax_t)sfsp->f_ffree);
558 		}
559 		if (inodes == 0)
560 			xo_emit(" {:inodes-used-percent/    -}{U:} ");
561 		else {
562 			xo_emit(" {:inodes-used-percent/%4.0f}{U:%%} ",
563 				(double)used / (double)inodes * 100.0);
564 		}
565 	} else
566 		xo_emit("  ");
567 	if (strncmp(sfsp->f_mntfromname, "total", MNAMELEN) != 0)
568 		xo_emit("  {:mounted-on}", sfsp->f_mntonname);
569 	xo_emit("\n");
570 	xo_close_instance("filesystem");
571 }
572 
573 static void
574 addstat(struct statfs *totalfsp, struct statfs *statfsp)
575 {
576 	uint64_t bsize;
577 
578 	bsize = statfsp->f_bsize / totalfsp->f_bsize;
579 	totalfsp->f_blocks += statfsp->f_blocks * bsize;
580 	totalfsp->f_bfree += statfsp->f_bfree * bsize;
581 	totalfsp->f_bavail += statfsp->f_bavail * bsize;
582 	totalfsp->f_files += statfsp->f_files;
583 	totalfsp->f_ffree += statfsp->f_ffree;
584 }
585 
586 /*
587  * Update the maximum field-width information in `mwp' based on
588  * the file system specified by `sfsp'.
589  */
590 static void
591 update_maxwidths(struct maxwidths *mwp, const struct statfs *sfsp)
592 {
593 	static long blocksize = 0;
594 	int dummy;
595 
596 	if (blocksize == 0)
597 		getbsize(&dummy, &blocksize);
598 
599 	mwp->mntfrom = imax(mwp->mntfrom, (int)strlen(sfsp->f_mntfromname));
600 	mwp->fstype = imax(mwp->fstype, (int)strlen(sfsp->f_fstypename));
601 	mwp->total = imax(mwp->total, int64width(
602 	    fsbtoblk((int64_t)sfsp->f_blocks, sfsp->f_bsize, blocksize)));
603 	mwp->used = imax(mwp->used,
604 	    int64width(fsbtoblk((int64_t)sfsp->f_blocks -
605 	    (int64_t)sfsp->f_bfree, sfsp->f_bsize, blocksize)));
606 	mwp->avail = imax(mwp->avail, int64width(fsbtoblk(sfsp->f_bavail,
607 	    sfsp->f_bsize, blocksize)));
608 	mwp->iused = imax(mwp->iused, int64width((int64_t)sfsp->f_files -
609 	    sfsp->f_ffree));
610 	mwp->ifree = imax(mwp->ifree, int64width(sfsp->f_ffree));
611 }
612 
613 /* Return the width in characters of the specified value. */
614 static int
615 int64width(int64_t val)
616 {
617 	int len;
618 
619 	len = 0;
620 	/* Negative or zero values require one extra digit. */
621 	if (val <= 0) {
622 		val = -val;
623 		len++;
624 	}
625 	while (val > 0) {
626 		len++;
627 		val /= 10;
628 	}
629 
630 	return (len);
631 }
632 
633 static void
634 usage(void)
635 {
636 
637 	xo_error(
638 "usage: df [-b | -g | -H | -h | -k | -m | -P] [-acilnT] [-t type] [-,]\n"
639 "          [file | filesystem ...]\n");
640 	exit(EX_USAGE);
641 }
642 
643 static char *
644 makenetvfslist(void)
645 {
646 	char *str, *strptr, **listptr;
647 	struct xvfsconf *xvfsp, *keep_xvfsp;
648 	size_t buflen;
649 	int cnt, i, maxvfsconf;
650 
651 	if (sysctlbyname("vfs.conflist", NULL, &buflen, NULL, 0) < 0) {
652 		xo_warn("sysctl(vfs.conflist)");
653 		return (NULL);
654 	}
655 	xvfsp = malloc(buflen);
656 	if (xvfsp == NULL) {
657 		xo_warnx("malloc failed");
658 		return (NULL);
659 	}
660 	keep_xvfsp = xvfsp;
661 	if (sysctlbyname("vfs.conflist", xvfsp, &buflen, NULL, 0) < 0) {
662 		xo_warn("sysctl(vfs.conflist)");
663 		free(keep_xvfsp);
664 		return (NULL);
665 	}
666 	maxvfsconf = buflen / sizeof(struct xvfsconf);
667 
668 	if ((listptr = malloc(sizeof(char*) * maxvfsconf)) == NULL) {
669 		xo_warnx("malloc failed");
670 		free(keep_xvfsp);
671 		return (NULL);
672 	}
673 
674 	for (cnt = 0, i = 0; i < maxvfsconf; i++) {
675 		if (xvfsp->vfc_flags & VFCF_NETWORK) {
676 			listptr[cnt++] = strdup(xvfsp->vfc_name);
677 			if (listptr[cnt-1] == NULL) {
678 				xo_warnx("malloc failed");
679 				free(listptr);
680 				free(keep_xvfsp);
681 				return (NULL);
682 			}
683 		}
684 		xvfsp++;
685 	}
686 
687 	if (cnt == 0 ||
688 	    (str = malloc(sizeof(char) * (32 * cnt + cnt + 2))) == NULL) {
689 		if (cnt > 0)
690 			xo_warnx("malloc failed");
691 		free(listptr);
692 		free(keep_xvfsp);
693 		return (NULL);
694 	}
695 
696 	*str = 'n'; *(str + 1) = 'o';
697 	for (i = 0, strptr = str + 2; i < cnt; i++, strptr++) {
698 		strlcpy(strptr, listptr[i], 32);
699 		strptr += strlen(listptr[i]);
700 		*strptr = ',';
701 		free(listptr[i]);
702 	}
703 	*(--strptr) = '\0';
704 
705 	free(keep_xvfsp);
706 	free(listptr);
707 	return (str);
708 }
709