xref: /freebsd/lib/libc/gen/sysconf.c (revision 3d8ce33a50d2ddac133ac799f4334d5b73f0b218)
1 /*-
2  * Copyright (c) 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Sean Eric Fagan of Cygnus Support.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. 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 defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)sysconf.c	8.2 (Berkeley) 3/20/94";
39 #endif /* LIBC_SCCS and not lint */
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 #include <sys/param.h>
44 #include <sys/time.h>
45 #include <sys/sysctl.h>
46 #include <sys/resource.h>
47 #include <sys/socket.h>
48 
49 #include <errno.h>
50 #include <limits.h>
51 #include <paths.h>
52 #include <pthread.h>		/* we just need the limits */
53 #include <time.h>
54 #include <unistd.h>
55 
56 #include "../stdlib/atexit.h"
57 #include "../stdtime/tzfile.h"
58 
59 #define	_PATH_ZONEINFO	TZDIR	/* from tzfile.h */
60 
61 /*
62  * sysconf --
63  *	get configurable system variables.
64  *
65  * XXX
66  * POSIX 1003.1 (ISO/IEC 9945-1, 4.8.1.3) states that the variable values
67  * not change during the lifetime of the calling process.  This would seem
68  * to require that any change to system limits kill all running processes.
69  * A workaround might be to cache the values when they are first retrieved
70  * and then simply return the cached value on subsequent calls.  This is
71  * less useful than returning up-to-date values, however.
72  */
73 long
74 sysconf(name)
75 	int name;
76 {
77 	struct rlimit rl;
78 	size_t len;
79 	int mib[2], sverrno, value;
80 	long defaultresult;
81 	const char *path;
82 
83 	len = sizeof(value);
84 	defaultresult = -1;
85 
86 	switch (name) {
87 	case _SC_ARG_MAX:
88 		mib[0] = CTL_KERN;
89 		mib[1] = KERN_ARGMAX;
90 		break;
91 	case _SC_CHILD_MAX:
92 		if (getrlimit(RLIMIT_NPROC, &rl) != 0)
93 			return (-1);
94 		if (rl.rlim_cur == RLIM_INFINITY)
95 			return (-1);
96 		if (rl.rlim_cur > LONG_MAX) {
97 			errno = EOVERFLOW;
98 			return (-1);
99 		}
100 		return ((long)rl.rlim_cur);
101 	case _SC_CLK_TCK:
102 		return (CLK_TCK);
103 	case _SC_NGROUPS_MAX:
104 		mib[0] = CTL_KERN;
105 		mib[1] = KERN_NGROUPS;
106 		break;
107 	case _SC_OPEN_MAX:
108 	case _SC_STREAM_MAX:	/* assume fds run out before memory does */
109 		if (getrlimit(RLIMIT_NOFILE, &rl) != 0)
110 			return (-1);
111 		if (rl.rlim_cur == RLIM_INFINITY)
112 			return (-1);
113 		if (rl.rlim_cur > LONG_MAX) {
114 			errno = EOVERFLOW;
115 			return (-1);
116 		}
117 		return ((long)rl.rlim_cur);
118 	case _SC_JOB_CONTROL:
119 		return (_POSIX_JOB_CONTROL);
120 	case _SC_SAVED_IDS:
121 		/* XXX - must be 1 */
122 		mib[0] = CTL_KERN;
123 		mib[1] = KERN_SAVED_IDS;
124 		goto yesno;
125 	case _SC_VERSION:
126 		mib[0] = CTL_KERN;
127 		mib[1] = KERN_POSIX1;
128 		break;
129 	case _SC_BC_BASE_MAX:
130 		return (BC_BASE_MAX);
131 	case _SC_BC_DIM_MAX:
132 		return (BC_DIM_MAX);
133 	case _SC_BC_SCALE_MAX:
134 		return (BC_SCALE_MAX);
135 	case _SC_BC_STRING_MAX:
136 		return (BC_STRING_MAX);
137 	case _SC_COLL_WEIGHTS_MAX:
138 		return (COLL_WEIGHTS_MAX);
139 	case _SC_EXPR_NEST_MAX:
140 		return (EXPR_NEST_MAX);
141 	case _SC_LINE_MAX:
142 		return (LINE_MAX);
143 	case _SC_RE_DUP_MAX:
144 		return (RE_DUP_MAX);
145 	case _SC_2_VERSION:
146 		/*
147 		 * This is something of a lie, but it would be silly at
148 		 * this point to try to deduce this from the contents
149 		 * of the filesystem.
150 		 */
151 		return (_POSIX2_VERSION);
152 	case _SC_2_C_BIND:
153 		return (_POSIX2_C_BIND);
154 	case _SC_2_C_DEV:
155 		return (_POSIX2_C_DEV);
156 	case _SC_2_CHAR_TERM:
157 		return (_POSIX2_CHAR_TERM);
158 	case _SC_2_FORT_DEV:
159 		return (_POSIX2_FORT_DEV);
160 	case _SC_2_FORT_RUN:
161 		return (_POSIX2_FORT_RUN);
162 	case _SC_2_LOCALEDEF:
163 		return (_POSIX2_LOCALEDEF);
164 	case _SC_2_SW_DEV:
165 		return (_POSIX2_SW_DEV);
166 	case _SC_2_UPE:
167 		return (_POSIX2_UPE);
168 	case _SC_TZNAME_MAX:
169 		path = _PATH_ZONEINFO;
170 do_NAME_MAX:
171 		sverrno = errno;
172 		errno = 0;
173 		value = pathconf(path, _PC_NAME_MAX);
174 		if (value == -1 && errno != 0)
175 			return (-1);
176 		errno = sverrno;
177 		return (value);
178 
179 	case _SC_ASYNCHRONOUS_IO:
180 #if _POSIX_ASYNCHRONOUS_IO == 0
181 		mib[0] = CTL_P1003_1B;
182 		mib[1] = CTL_P1003_1B_ASYNCHRONOUS_IO;
183 		break;
184 #else
185 		return (_POSIX_ASYNCHRONOUS_IO);
186 #endif
187 	case _SC_MAPPED_FILES:
188 		return (_POSIX_MAPPED_FILES);
189 	case _SC_MEMLOCK:
190 		return (_POSIX_MEMLOCK);
191 	case _SC_MEMLOCK_RANGE:
192 		return (_POSIX_MEMLOCK_RANGE);
193 	case _SC_MEMORY_PROTECTION:
194 		return (_POSIX_MEMORY_PROTECTION);
195 	case _SC_MESSAGE_PASSING:
196 #if _POSIX_MESSAGE_PASSING == 0
197 		mib[0] = CTL_P1003_1B;
198 		mib[1] = CTL_P1003_1B_MESSAGE_PASSING;
199 		goto yesno;
200 #else
201 		return (_POSIX_MESSAGE_PASSING);
202 #endif
203 	case _SC_PRIORITIZED_IO:
204 #if _POSIX_PRIORITIZED_IO == 0
205 		mib[0] = CTL_P1003_1B;
206 		mib[1] = CTL_P1003_1B_PRIORITIZED_IO;
207 		goto yesno;
208 #else
209 		return (_POSIX_PRIORITIZED_IO);
210 #endif
211 	case _SC_PRIORITY_SCHEDULING:
212 #if _POSIX_PRIORITY_SCHEDULING == 0
213 		mib[0] = CTL_P1003_1B;
214 		mib[1] = CTL_P1003_1B_PRIORITY_SCHEDULING;
215 		goto yesno;
216 #else
217 		return (_POSIX_PRIORITY_SCHEDULING);
218 #endif
219 	case _SC_REALTIME_SIGNALS:
220 #if _POSIX_REALTIME_SIGNALS == 0
221 		mib[0] = CTL_P1003_1B;
222 		mib[1] = CTL_P1003_1B_REALTIME_SIGNALS;
223 		goto yesno;
224 #else
225 		return (_POSIX_REALTIME_SIGNALS);
226 #endif
227 	case _SC_SEMAPHORES:
228 #if _POSIX_SEMAPHORES == 0
229 		mib[0] = CTL_P1003_1B;
230 		mib[1] = CTL_P1003_1B_SEMAPHORES;
231 		goto yesno;
232 #else
233 		return (_POSIX_SEMAPHORES);
234 #endif
235 	case _SC_FSYNC:
236 		return (_POSIX_FSYNC);
237 
238 	case _SC_SHARED_MEMORY_OBJECTS:
239 		return (_POSIX_SHARED_MEMORY_OBJECTS);
240 	case _SC_SYNCHRONIZED_IO:
241 #if _POSIX_SYNCHRONIZED_IO == 0
242 		mib[0] = CTL_P1003_1B;
243 		mib[1] = CTL_P1003_1B_SYNCHRONIZED_IO;
244 		goto yesno;
245 #else
246 		return (_POSIX_SYNCHRONIZED_IO);
247 #endif
248 	case _SC_TIMERS:
249 #if _POSIX_TIMERS == 0
250 		mib[0] = CTL_P1003_1B;
251 		mib[1] = CTL_P1003_1B_TIMERS;
252 		goto yesno;
253 #else
254 		return (_POSIX_TIMERS);
255 #endif
256 	case _SC_AIO_LISTIO_MAX:
257 		defaultresult = _POSIX_AIO_LISTIO_MAX;
258 		mib[0] = CTL_P1003_1B;
259 		mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
260 		goto yesno;
261 	case _SC_AIO_MAX:
262 		defaultresult = _POSIX_AIO_MAX;
263 		mib[0] = CTL_P1003_1B;
264 		mib[1] = CTL_P1003_1B_AIO_MAX;
265 		goto yesno;
266 	case _SC_AIO_PRIO_DELTA_MAX:
267 		defaultresult = 0;
268 		mib[0] = CTL_P1003_1B;
269 		mib[1] = CTL_P1003_1B_AIO_PRIO_DELTA_MAX;
270 		goto yesno;
271 	case _SC_DELAYTIMER_MAX:
272 		mib[0] = CTL_P1003_1B;
273 		mib[1] = CTL_P1003_1B_DELAYTIMER_MAX;
274 		goto yesno;
275 	case _SC_MQ_OPEN_MAX:
276 		mib[0] = CTL_P1003_1B;
277 		mib[1] = CTL_P1003_1B_MQ_OPEN_MAX;
278 		goto yesno;
279 	case _SC_PAGESIZE:
280 		defaultresult = getpagesize();
281 		mib[0] = CTL_P1003_1B;
282 		mib[1] = CTL_P1003_1B_PAGESIZE;
283 		goto yesno;
284 	case _SC_RTSIG_MAX:
285 		mib[0] = CTL_P1003_1B;
286 		mib[1] = CTL_P1003_1B_RTSIG_MAX;
287 		goto yesno;
288 	case _SC_SEM_NSEMS_MAX:
289 		mib[0] = CTL_P1003_1B;
290 		mib[1] = CTL_P1003_1B_SEM_NSEMS_MAX;
291 		goto yesno;
292 	case _SC_SEM_VALUE_MAX:
293 		mib[0] = CTL_P1003_1B;
294 		mib[1] = CTL_P1003_1B_SEM_VALUE_MAX;
295 		goto yesno;
296 	case _SC_SIGQUEUE_MAX:
297 		mib[0] = CTL_P1003_1B;
298 		mib[1] = CTL_P1003_1B_SIGQUEUE_MAX;
299 		goto yesno;
300 	case _SC_TIMER_MAX:
301 		mib[0] = CTL_P1003_1B;
302 		mib[1] = CTL_P1003_1B_TIMER_MAX;
303 
304 yesno:		if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
305 			return (-1);
306 		if (value == 0)
307 			return (defaultresult);
308 		return (value);
309 
310 	case _SC_2_PBS:
311 	case _SC_2_PBS_ACCOUNTING:
312 	case _SC_2_PBS_CHECKPOINT:
313 	case _SC_2_PBS_LOCATE:
314 	case _SC_2_PBS_MESSAGE:
315 	case _SC_2_PBS_TRACK:
316 #if _POSIX2_PBS == 0
317 #error "don't know how to determine _SC_2_PBS"
318 		/*
319 		 * This probably requires digging through the filesystem
320 		 * to see if the appropriate package has been installed.
321 		 * Since we don't currently support this option at all,
322 		 * it's not worth the effort to write the code now.
323 		 * Figuring out which of the sub-options are supported
324 		 * would be even more difficult, so it's probably easier
325 		 * to always say ``no''.
326 		 */
327 #else
328 		return (_POSIX2_PBS);
329 #endif
330 	case _SC_ADVISORY_INFO:
331 #if _POSIX_ADVISORY_INFO == 0
332 #error "_POSIX_ADVISORY_INFO"
333 #else
334 		return (_POSIX_ADVISORY_INFO);
335 #endif
336 	case _SC_BARRIERS:
337 #if _POSIX_BARRIERS == 0
338 #error "_POSIX_BARRIERS"
339 #else
340 		return (_POSIX_BARRIERS);
341 #endif
342 	case _SC_CLOCK_SELECTION:
343 #if _POSIX_CLOCK_SELECTION == 0
344 #error "_POSIX_CLOCK_SELECTION"
345 #else
346 		return (_POSIX_CLOCK_SELECTION);
347 #endif
348 	case _SC_CPUTIME:
349 #if _POSIX_CPUTIME == 0
350 #error "_POSIX_CPUTIME"
351 #else
352 		return (_POSIX_CPUTIME);
353 #endif
354 #ifdef notdef
355 	case _SC_FILE_LOCKING:
356 		/*
357 		 * XXX - The standard doesn't tell us how to define
358 		 * _POSIX_FILE_LOCKING, so we can't answer this one.
359 		 */
360 #endif
361 #if _POSIX_THREAD_SAFE_FUNCTIONS > -1
362 	case _SC_GETGR_R_SIZE_MAX:
363 	case _SC_GETPW_R_SIZE_MAX:
364 #error "somebody needs to implement this"
365 #endif
366 	case _SC_HOST_NAME_MAX:
367 		return (MAXHOSTNAMELEN - 1); /* does not include \0 */
368 	case _SC_LOGIN_NAME_MAX:
369 		return (MAXLOGNAME);
370 	case _SC_MONOTONIC_CLOCK:
371 #if _POSIX_MONOTONIC_CLOCK == 0
372 #error "_POSIX_MONOTONIC_CLOCK"
373 #else
374 		return (_POSIX_MONOTONIC_CLOCK);
375 #endif
376 #if _POSIX_MESSAGE_PASSING > -1
377 	case _SC_MQ_PRIO_MAX:
378 		return (MQ_PRIO_MAX);
379 #endif
380 	case _SC_READER_WRITER_LOCKS:
381 		return (_POSIX_READER_WRITER_LOCKS);
382 	case _SC_REGEXP:
383 		return (_POSIX_REGEXP);
384 	case _SC_SHELL:
385 		return (_POSIX_SHELL);
386 	case _SC_SPAWN:
387 		return (_POSIX_SPAWN);
388 	case _SC_SPIN_LOCKS:
389 		return (_POSIX_SPIN_LOCKS);
390 	case _SC_SPORADIC_SERVER:
391 #if _POSIX_SPORADIC_SERVER == 0
392 #error "_POSIX_SPORADIC_SERVER"
393 #else
394 		return (_POSIX_SPORADIC_SERVER);
395 #endif
396 	case _SC_THREAD_ATTR_STACKADDR:
397 		return (_POSIX_THREAD_ATTR_STACKADDR);
398 	case _SC_THREAD_ATTR_STACKSIZE:
399 		return (_POSIX_THREAD_ATTR_STACKSIZE);
400 	case _SC_THREAD_CPUTIME:
401 		return (_POSIX_THREAD_CPUTIME);
402 	case _SC_THREAD_DESTRUCTOR_ITERATIONS:
403 		return (PTHREAD_DESTRUCTOR_ITERATIONS);
404 	case _SC_THREAD_KEYS_MAX:
405 		return (PTHREAD_KEYS_MAX);
406 	case _SC_THREAD_PRIO_INHERIT:
407 		return (_POSIX_THREAD_PRIO_INHERIT);
408 	case _SC_THREAD_PRIO_PROTECT:
409 		return (_POSIX_THREAD_PRIO_PROTECT);
410 	case _SC_THREAD_PRIORITY_SCHEDULING:
411 		return (_POSIX_THREAD_PRIORITY_SCHEDULING);
412 	case _SC_THREAD_PROCESS_SHARED:
413 		return (_POSIX_THREAD_PROCESS_SHARED);
414 	case _SC_THREAD_SAFE_FUNCTIONS:
415 		return (_POSIX_THREAD_SAFE_FUNCTIONS);
416 	case _SC_THREAD_STACK_MIN:
417 		return (PTHREAD_STACK_MIN);
418 	case _SC_THREAD_THREADS_MAX:
419 		return (PTHREAD_THREADS_MAX); /* XXX wrong type! */
420 	case _SC_TIMEOUTS:
421 		return (_POSIX_TIMEOUTS);
422 	case _SC_THREADS:
423 		return (_POSIX_THREADS);
424 	case _SC_TRACE:
425 #if _POSIX_TRACE == 0
426 #error "_POSIX_TRACE"
427 		/* While you're implementing this, also do the ones below. */
428 #else
429 		return (_POSIX_TRACE);
430 #endif
431 #if _POSIX_TRACE > -1
432 	case _SC_TRACE_EVENT_FILTER:
433 		return (_POSIX_TRACE_EVENT_FILTER);
434 	case _SC_TRACE_INHERIT:
435 		return (_POSIX_TRACE_INHERIT);
436 	case _SC_TRACE_LOG:
437 		return (_POSIX_TRACE_LOG);
438 #endif
439 	case _SC_TTY_NAME_MAX:
440 		path = _PATH_DEV;
441 		goto do_NAME_MAX;
442 	case _SC_TYPED_MEMORY_OBJECTS:
443 #if _POSIX_TYPED_MEMORY_OBJECTS == 0
444 #error "_POSIX_TYPED_MEMORY_OBJECTS"
445 #else
446 		return (_POSIX_TYPED_MEMORY_OBJECTS);
447 #endif
448 	case _SC_V6_ILP32_OFF32:
449 #if _V6_ILP32_OFF32 == 0
450 		if (sizeof(int) * CHAR_BIT == 32 &&
451 		    sizeof(int) == sizeof(long) &&
452 		    sizeof(long) == sizeof(void *) &&
453 		    sizeof(void *) == sizeof(off_t))
454 			return 1;
455 		else
456 			return -1;
457 #else
458 		return (_V6_ILP32_OFF32);
459 #endif
460 	case _SC_V6_ILP32_OFFBIG:
461 #if _V6_ILP32_OFFBIG == 0
462 		if (sizeof(int) * CHAR_BIT == 32 &&
463 		    sizeof(int) == sizeof(long) &&
464 		    sizeof(long) == sizeof(void *) &&
465 		    sizeof(off_t) * CHAR_BIT >= 64)
466 			return 1;
467 		else
468 			return -1;
469 #else
470 		return (_V6_ILP32_OFFBIG);
471 #endif
472 	case _SC_V6_LP64_OFF64:
473 #if _V6_LP64_OFF64 == 0
474 		if (sizeof(int) * CHAR_BIT == 32 &&
475 		    sizeof(long) * CHAR_BIT == 64 &&
476 		    sizeof(long) == sizeof(void *) &&
477 		    sizeof(void *) == sizeof(off_t))
478 			return 1;
479 		else
480 			return -1;
481 #else
482 		return (_V6_LP64_OFF64);
483 #endif
484 	case _SC_V6_LPBIG_OFFBIG:
485 #if _V6_LPBIG_OFFBIG == 0
486 		if (sizeof(int) * CHAR_BIT >= 32 &&
487 		    sizeof(long) * CHAR_BIT >= 64 &&
488 		    sizeof(void *) * CHAR_BIT >= 64 &&
489 		    sizeof(off_t) * CHAR_BIT >= 64)
490 			return 1;
491 		else
492 			return -1;
493 #else
494 		return (_V6_LPBIG_OFFBIG);
495 #endif
496 	case _SC_ATEXIT_MAX:
497 		return (ATEXIT_SIZE);
498 	case _SC_IOV_MAX:
499 		mib[0] = CTL_KERN;
500 		mib[1] = KERN_IOV_MAX;
501 		break;
502 	case _SC_XOPEN_CRYPT:
503 		return (_XOPEN_CRYPT);
504 	case _SC_XOPEN_ENH_I18N:
505 		return (_XOPEN_ENH_I18N);
506 	case _SC_XOPEN_LEGACY:
507 		return (_XOPEN_LEGACY);
508 	case _SC_XOPEN_REALTIME:
509 #if _XOPEN_REALTIME == 0
510 		sverrno = errno;
511 		value = sysconf(_SC_ASYNCHRONOUS_IO) > 0 &&
512 			sysconf(_SC_MEMLOCK) > 0 &&
513 			sysconf(_SC_MEMLOCK_RANGE) > 0 &&
514 			sysconf(_SC_MESSAGE_PASSING) > 0 &&
515 			sysconf(_SC_PRIORITY_SCHEDULING) > 0 &&
516 			sysconf(_SC_REALTIME_SIGNALS) > 0 &&
517 			sysconf(_SC_SEMAPHORES) > 0 &&
518 			sysconf(_SC_SHARED_MEMORY_OBJECTS) > 0 &&
519 			sysconf(_SC_SYNCHRONIZED_IO) > 0 &&
520 			sysconf(_SC_TIMERS) > 0;
521 		errno = sverrno;
522 		if (value)
523 			return (200112L);
524 		else
525 			return (-1);
526 #else
527 		return (_XOPEN_REALTIME);
528 #endif
529 	case _SC_XOPEN_REALTIME_THREADS:
530 #if _XOPEN_REALTIME_THREADS == 0
531 #error "_XOPEN_REALTIME_THREADS"
532 #else
533 		return (_XOPEN_REALTIME_THREADS);
534 #endif
535 	case _SC_XOPEN_SHM:
536 		sverrno = errno;
537 		if (sysctlbyname("kern.ipc.shmmin", &value, &len, NULL,
538 		    0) == -1) {
539 			errno = sverrno;
540 			return (-1);
541 		}
542 		errno = sverrno;
543 		return (1);
544 	case _SC_XOPEN_STREAMS:
545 		return (_XOPEN_STREAMS);
546 	case _SC_XOPEN_UNIX:
547 		return (_XOPEN_UNIX);
548 #ifdef _XOPEN_VERSION
549 	case _SC_XOPEN_VERSION:
550 		return (_XOPEN_VERSION);
551 #endif
552 #ifdef _XOPEN_XCU_VERSION
553 	case _SC_XOPEN_XCU_VERSION:
554 		return (_XOPEN_XCU_VERSION);
555 #endif
556 	case _SC_SYMLOOP_MAX:
557 		return (MAXSYMLINKS);
558 	case _SC_RAW_SOCKETS:
559 		return (_POSIX_RAW_SOCKETS);
560 	case _SC_IPV6:
561 #if _POSIX_IPV6 == 0
562 		sverrno = errno;
563 		value = socket(PF_INET6, SOCK_DGRAM, 0);
564 		errno = sverrno;
565 		if (value >= 0) {
566 			close(value);
567 			return (200112L);
568 		} else
569 			return (0);
570 #else
571 		return (_POSIX_IPV6);
572 #endif
573 
574 	case _SC_NPROCESSORS_CONF:
575 	case _SC_NPROCESSORS_ONLN:
576 		mib[0] = CTL_HW;
577 		mib[1] = HW_NCPU;
578 		break;
579 
580 	default:
581 		errno = EINVAL;
582 		return (-1);
583 	}
584 	return (sysctl(mib, 2, &value, &len, NULL, 0) == -1 ? -1 : value);
585 }
586