xref: /freebsd/lib/libc/gen/sysconf.c (revision d056fa046c6a91b90cd98165face0e42a33a5173)
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 		mib[0] = CTL_P1003_1B;
258 		mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
259 		break;
260 	case _SC_AIO_MAX:
261 		mib[0] = CTL_P1003_1B;
262 		mib[1] = CTL_P1003_1B_AIO_MAX;
263 		break;
264 	case _SC_AIO_PRIO_DELTA_MAX:
265 		mib[0] = CTL_P1003_1B;
266 		mib[1] = CTL_P1003_1B_AIO_PRIO_DELTA_MAX;
267 		break;
268 	case _SC_DELAYTIMER_MAX:
269 		mib[0] = CTL_P1003_1B;
270 		mib[1] = CTL_P1003_1B_DELAYTIMER_MAX;
271 		goto yesno;
272 	case _SC_MQ_OPEN_MAX:
273 		mib[0] = CTL_P1003_1B;
274 		mib[1] = CTL_P1003_1B_MQ_OPEN_MAX;
275 		goto yesno;
276 	case _SC_PAGESIZE:
277 		defaultresult = getpagesize();
278 		mib[0] = CTL_P1003_1B;
279 		mib[1] = CTL_P1003_1B_PAGESIZE;
280 		goto yesno;
281 	case _SC_RTSIG_MAX:
282 		mib[0] = CTL_P1003_1B;
283 		mib[1] = CTL_P1003_1B_RTSIG_MAX;
284 		goto yesno;
285 	case _SC_SEM_NSEMS_MAX:
286 		mib[0] = CTL_P1003_1B;
287 		mib[1] = CTL_P1003_1B_SEM_NSEMS_MAX;
288 		goto yesno;
289 	case _SC_SEM_VALUE_MAX:
290 		mib[0] = CTL_P1003_1B;
291 		mib[1] = CTL_P1003_1B_SEM_VALUE_MAX;
292 		goto yesno;
293 	case _SC_SIGQUEUE_MAX:
294 		mib[0] = CTL_P1003_1B;
295 		mib[1] = CTL_P1003_1B_SIGQUEUE_MAX;
296 		goto yesno;
297 	case _SC_TIMER_MAX:
298 		mib[0] = CTL_P1003_1B;
299 		mib[1] = CTL_P1003_1B_TIMER_MAX;
300 
301 yesno:		if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
302 			return (-1);
303 		if (value == 0)
304 			return (defaultresult);
305 		return (value);
306 
307 	case _SC_2_PBS:
308 	case _SC_2_PBS_ACCOUNTING:
309 	case _SC_2_PBS_CHECKPOINT:
310 	case _SC_2_PBS_LOCATE:
311 	case _SC_2_PBS_MESSAGE:
312 	case _SC_2_PBS_TRACK:
313 #if _POSIX2_PBS == 0
314 #error "don't know how to determine _SC_2_PBS"
315 		/*
316 		 * This probably requires digging through the filesystem
317 		 * to see if the appropriate package has been installed.
318 		 * Since we don't currently support this option at all,
319 		 * it's not worth the effort to write the code now.
320 		 * Figuring out which of the sub-options are supported
321 		 * would be even more difficult, so it's probably easier
322 		 * to always say ``no''.
323 		 */
324 #else
325 		return (_POSIX2_PBS);
326 #endif
327 	case _SC_ADVISORY_INFO:
328 #if _POSIX_ADVISORY_INFO == 0
329 #error "_POSIX_ADVISORY_INFO"
330 #else
331 		return (_POSIX_ADVISORY_INFO);
332 #endif
333 	case _SC_BARRIERS:
334 #if _POSIX_BARRIERS == 0
335 #error "_POSIX_BARRIERS"
336 #else
337 		return (_POSIX_BARRIERS);
338 #endif
339 	case _SC_CLOCK_SELECTION:
340 #if _POSIX_CLOCK_SELECTION == 0
341 #error "_POSIX_CLOCK_SELECTION"
342 #else
343 		return (_POSIX_CLOCK_SELECTION);
344 #endif
345 	case _SC_CPUTIME:
346 #if _POSIX_CPUTIME == 0
347 #error "_POSIX_CPUTIME"
348 #else
349 		return (_POSIX_CPUTIME);
350 #endif
351 #ifdef notdef
352 	case _SC_FILE_LOCKING:
353 		/*
354 		 * XXX - The standard doesn't tell us how to define
355 		 * _POSIX_FILE_LOCKING, so we can't answer this one.
356 		 */
357 #endif
358 #if _POSIX_THREAD_SAFE_FUNCTIONS > -1
359 	case _SC_GETGR_R_SIZE_MAX:
360 	case _SC_GETPW_R_SIZE_MAX:
361 #error "somebody needs to implement this"
362 #endif
363 	case _SC_HOST_NAME_MAX:
364 		return (MAXHOSTNAMELEN - 1); /* does not include \0 */
365 	case _SC_LOGIN_NAME_MAX:
366 		return (MAXLOGNAME);
367 	case _SC_MONOTONIC_CLOCK:
368 #if _POSIX_MONOTONIC_CLOCK == 0
369 #error "_POSIX_MONOTONIC_CLOCK"
370 #else
371 		return (_POSIX_MONOTONIC_CLOCK);
372 #endif
373 #if _POSIX_MESSAGE_PASSING > -1
374 	case _SC_MQ_PRIO_MAX:
375 		return (MQ_PRIO_MAX);
376 #endif
377 	case _SC_READER_WRITER_LOCKS:
378 		return (_POSIX_READER_WRITER_LOCKS);
379 	case _SC_REGEXP:
380 		return (_POSIX_REGEXP);
381 	case _SC_SHELL:
382 		return (_POSIX_SHELL);
383 	case _SC_SPAWN:
384 		return (_POSIX_SPAWN);
385 	case _SC_SPIN_LOCKS:
386 		return (_POSIX_SPIN_LOCKS);
387 	case _SC_SPORADIC_SERVER:
388 #if _POSIX_SPORADIC_SERVER == 0
389 #error "_POSIX_SPORADIC_SERVER"
390 #else
391 		return (_POSIX_SPORADIC_SERVER);
392 #endif
393 	case _SC_THREAD_ATTR_STACKADDR:
394 		return (_POSIX_THREAD_ATTR_STACKADDR);
395 	case _SC_THREAD_ATTR_STACKSIZE:
396 		return (_POSIX_THREAD_ATTR_STACKSIZE);
397 	case _SC_THREAD_CPUTIME:
398 		return (_POSIX_THREAD_CPUTIME);
399 	case _SC_THREAD_DESTRUCTOR_ITERATIONS:
400 		return (PTHREAD_DESTRUCTOR_ITERATIONS);
401 	case _SC_THREAD_KEYS_MAX:
402 		return (PTHREAD_KEYS_MAX);
403 	case _SC_THREAD_PRIO_INHERIT:
404 		return (_POSIX_THREAD_PRIO_INHERIT);
405 	case _SC_THREAD_PRIO_PROTECT:
406 		return (_POSIX_THREAD_PRIO_PROTECT);
407 	case _SC_THREAD_PRIORITY_SCHEDULING:
408 		return (_POSIX_THREAD_PRIORITY_SCHEDULING);
409 	case _SC_THREAD_PROCESS_SHARED:
410 		return (_POSIX_THREAD_PROCESS_SHARED);
411 	case _SC_THREAD_SAFE_FUNCTIONS:
412 		return (_POSIX_THREAD_SAFE_FUNCTIONS);
413 	case _SC_THREAD_STACK_MIN:
414 		return (PTHREAD_STACK_MIN);
415 	case _SC_THREAD_THREADS_MAX:
416 		return (PTHREAD_THREADS_MAX); /* XXX wrong type! */
417 	case _SC_TIMEOUTS:
418 		return (_POSIX_TIMEOUTS);
419 	case _SC_THREADS:
420 		return (_POSIX_THREADS);
421 	case _SC_TRACE:
422 #if _POSIX_TRACE == 0
423 #error "_POSIX_TRACE"
424 		/* While you're implementing this, also do the ones below. */
425 #else
426 		return (_POSIX_TRACE);
427 #endif
428 #if _POSIX_TRACE > -1
429 	case _SC_TRACE_EVENT_FILTER:
430 		return (_POSIX_TRACE_EVENT_FILTER);
431 	case _SC_TRACE_INHERIT:
432 		return (_POSIX_TRACE_INHERIT);
433 	case _SC_TRACE_LOG:
434 		return (_POSIX_TRACE_LOG);
435 #endif
436 	case _SC_TTY_NAME_MAX:
437 		path = _PATH_DEV;
438 		goto do_NAME_MAX;
439 	case _SC_TYPED_MEMORY_OBJECTS:
440 #if _POSIX_TYPED_MEMORY_OBJECTS == 0
441 #error "_POSIX_TYPED_MEMORY_OBJECTS"
442 #else
443 		return (_POSIX_TYPED_MEMORY_OBJECTS);
444 #endif
445 	case _SC_V6_ILP32_OFF32:
446 #if _V6_ILP32_OFF32 == 0
447 		if (sizeof(int) * CHAR_BIT == 32 &&
448 		    sizeof(int) == sizeof(long) &&
449 		    sizeof(long) == sizeof(void *) &&
450 		    sizeof(void *) == sizeof(off_t))
451 			return 1;
452 		else
453 			return -1;
454 #else
455 		return (_V6_ILP32_OFF32);
456 #endif
457 	case _SC_V6_ILP32_OFFBIG:
458 #if _V6_ILP32_OFFBIG == 0
459 		if (sizeof(int) * CHAR_BIT == 32 &&
460 		    sizeof(int) == sizeof(long) &&
461 		    sizeof(long) == sizeof(void *) &&
462 		    sizeof(off_t) * CHAR_BIT >= 64)
463 			return 1;
464 		else
465 			return -1;
466 #else
467 		return (_V6_ILP32_OFFBIG);
468 #endif
469 	case _SC_V6_LP64_OFF64:
470 #if _V6_LP64_OFF64 == 0
471 		if (sizeof(int) * CHAR_BIT == 32 &&
472 		    sizeof(long) * CHAR_BIT == 64 &&
473 		    sizeof(long) == sizeof(void *) &&
474 		    sizeof(void *) == sizeof(off_t))
475 			return 1;
476 		else
477 			return -1;
478 #else
479 		return (_V6_LP64_OFF64);
480 #endif
481 	case _SC_V6_LPBIG_OFFBIG:
482 #if _V6_LPBIG_OFFBIG == 0
483 		if (sizeof(int) * CHAR_BIT >= 32 &&
484 		    sizeof(long) * CHAR_BIT >= 64 &&
485 		    sizeof(void *) * CHAR_BIT >= 64 &&
486 		    sizeof(off_t) * CHAR_BIT >= 64)
487 			return 1;
488 		else
489 			return -1;
490 #else
491 		return (_V6_LPBIG_OFFBIG);
492 #endif
493 	case _SC_ATEXIT_MAX:
494 		return (ATEXIT_SIZE);
495 	case _SC_IOV_MAX:
496 		mib[0] = CTL_KERN;
497 		mib[1] = KERN_IOV_MAX;
498 		break;
499 	case _SC_XOPEN_CRYPT:
500 		return (_XOPEN_CRYPT);
501 	case _SC_XOPEN_ENH_I18N:
502 		return (_XOPEN_ENH_I18N);
503 	case _SC_XOPEN_LEGACY:
504 		return (_XOPEN_LEGACY);
505 	case _SC_XOPEN_REALTIME:
506 #if _XOPEN_REALTIME == 0
507 		sverrno = errno;
508 		value = sysconf(_SC_ASYNCHRONOUS_IO) > 0 &&
509 			sysconf(_SC_MEMLOCK) > 0 &&
510 			sysconf(_SC_MEMLOCK_RANGE) > 0 &&
511 			sysconf(_SC_MESSAGE_PASSING) > 0 &&
512 			sysconf(_SC_PRIORITY_SCHEDULING) > 0 &&
513 			sysconf(_SC_REALTIME_SIGNALS) > 0 &&
514 			sysconf(_SC_SEMAPHORES) > 0 &&
515 			sysconf(_SC_SHARED_MEMORY_OBJECTS) > 0 &&
516 			sysconf(_SC_SYNCHRONIZED_IO) > 0 &&
517 			sysconf(_SC_TIMERS) > 0;
518 		errno = sverrno;
519 		if (value)
520 			return (200112L);
521 		else
522 			return (-1);
523 #else
524 		return (_XOPEN_REALTIME);
525 #endif
526 	case _SC_XOPEN_REALTIME_THREADS:
527 #if _XOPEN_REALTIME_THREADS == 0
528 #error "_XOPEN_REALTIME_THREADS"
529 #else
530 		return (_XOPEN_REALTIME_THREADS);
531 #endif
532 	case _SC_XOPEN_SHM:
533 		sverrno = errno;
534 		if (sysctlbyname("kern.ipc.shmmin", &value, &len, NULL,
535 		    0) == -1) {
536 			errno = sverrno;
537 			return (-1);
538 		}
539 		errno = sverrno;
540 		return (1);
541 	case _SC_XOPEN_STREAMS:
542 		return (_XOPEN_STREAMS);
543 	case _SC_XOPEN_UNIX:
544 		return (_XOPEN_UNIX);
545 #ifdef _XOPEN_VERSION
546 	case _SC_XOPEN_VERSION:
547 		return (_XOPEN_VERSION);
548 #endif
549 #ifdef _XOPEN_XCU_VERSION
550 	case _SC_XOPEN_XCU_VERSION:
551 		return (_XOPEN_XCU_VERSION);
552 #endif
553 	case _SC_SYMLOOP_MAX:
554 		return (MAXSYMLINKS);
555 	case _SC_RAW_SOCKETS:
556 		return (_POSIX_RAW_SOCKETS);
557 	case _SC_IPV6:
558 #if _POSIX_IPV6 == 0
559 		sverrno = errno;
560 		value = socket(PF_INET6, SOCK_DGRAM, 0);
561 		errno = sverrno;
562 		if (value >= 0) {
563 			close(value);
564 			return (200112L);
565 		} else
566 			return (0);
567 #else
568 		return (_POSIX_IPV6);
569 #endif
570 
571 	case _SC_NPROCESSORS_CONF:
572 	case _SC_NPROCESSORS_ONLN:
573 		mib[0] = CTL_HW;
574 		mib[1] = HW_NCPU;
575 		break;
576 
577 	default:
578 		errno = EINVAL;
579 		return (-1);
580 	}
581 	return (sysctl(mib, 2, &value, &len, NULL, 0) == -1 ? -1 : value);
582 }
583