xref: /freebsd/lib/libc/gen/sysconf.c (revision f856af0466c076beef4ea9b15d088e1119a945b8)
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 	const char *sname;
83 
84 	len = sizeof(value);
85 	defaultresult = -1;
86 	sname = NULL;
87 
88 	switch (name) {
89 	case _SC_ARG_MAX:
90 		mib[0] = CTL_KERN;
91 		mib[1] = KERN_ARGMAX;
92 		break;
93 	case _SC_CHILD_MAX:
94 		if (getrlimit(RLIMIT_NPROC, &rl) != 0)
95 			return (-1);
96 		if (rl.rlim_cur == RLIM_INFINITY)
97 			return (-1);
98 		if (rl.rlim_cur > LONG_MAX) {
99 			errno = EOVERFLOW;
100 			return (-1);
101 		}
102 		return ((long)rl.rlim_cur);
103 	case _SC_CLK_TCK:
104 		return (CLK_TCK);
105 	case _SC_NGROUPS_MAX:
106 		mib[0] = CTL_KERN;
107 		mib[1] = KERN_NGROUPS;
108 		break;
109 	case _SC_OPEN_MAX:
110 	case _SC_STREAM_MAX:	/* assume fds run out before memory does */
111 		if (getrlimit(RLIMIT_NOFILE, &rl) != 0)
112 			return (-1);
113 		if (rl.rlim_cur == RLIM_INFINITY)
114 			return (-1);
115 		if (rl.rlim_cur > LONG_MAX) {
116 			errno = EOVERFLOW;
117 			return (-1);
118 		}
119 		return ((long)rl.rlim_cur);
120 	case _SC_JOB_CONTROL:
121 		return (_POSIX_JOB_CONTROL);
122 	case _SC_SAVED_IDS:
123 		/* XXX - must be 1 */
124 		mib[0] = CTL_KERN;
125 		mib[1] = KERN_SAVED_IDS;
126 		goto yesno;
127 	case _SC_VERSION:
128 		mib[0] = CTL_KERN;
129 		mib[1] = KERN_POSIX1;
130 		break;
131 	case _SC_BC_BASE_MAX:
132 		return (BC_BASE_MAX);
133 	case _SC_BC_DIM_MAX:
134 		return (BC_DIM_MAX);
135 	case _SC_BC_SCALE_MAX:
136 		return (BC_SCALE_MAX);
137 	case _SC_BC_STRING_MAX:
138 		return (BC_STRING_MAX);
139 	case _SC_COLL_WEIGHTS_MAX:
140 		return (COLL_WEIGHTS_MAX);
141 	case _SC_EXPR_NEST_MAX:
142 		return (EXPR_NEST_MAX);
143 	case _SC_LINE_MAX:
144 		return (LINE_MAX);
145 	case _SC_RE_DUP_MAX:
146 		return (RE_DUP_MAX);
147 	case _SC_2_VERSION:
148 		/*
149 		 * This is something of a lie, but it would be silly at
150 		 * this point to try to deduce this from the contents
151 		 * of the filesystem.
152 		 */
153 		return (_POSIX2_VERSION);
154 	case _SC_2_C_BIND:
155 		return (_POSIX2_C_BIND);
156 	case _SC_2_C_DEV:
157 		return (_POSIX2_C_DEV);
158 	case _SC_2_CHAR_TERM:
159 		return (_POSIX2_CHAR_TERM);
160 	case _SC_2_FORT_DEV:
161 		return (_POSIX2_FORT_DEV);
162 	case _SC_2_FORT_RUN:
163 		return (_POSIX2_FORT_RUN);
164 	case _SC_2_LOCALEDEF:
165 		return (_POSIX2_LOCALEDEF);
166 	case _SC_2_SW_DEV:
167 		return (_POSIX2_SW_DEV);
168 	case _SC_2_UPE:
169 		return (_POSIX2_UPE);
170 	case _SC_TZNAME_MAX:
171 		path = _PATH_ZONEINFO;
172 do_NAME_MAX:
173 		sverrno = errno;
174 		errno = 0;
175 		value = pathconf(path, _PC_NAME_MAX);
176 		if (value == -1 && errno != 0)
177 			return (-1);
178 		errno = sverrno;
179 		return (value);
180 
181 	case _SC_ASYNCHRONOUS_IO:
182 #if _POSIX_ASYNCHRONOUS_IO == 0
183 		mib[0] = CTL_P1003_1B;
184 		mib[1] = CTL_P1003_1B_ASYNCHRONOUS_IO;
185 		break;
186 #else
187 		return (_POSIX_ASYNCHRONOUS_IO);
188 #endif
189 	case _SC_MAPPED_FILES:
190 		return (_POSIX_MAPPED_FILES);
191 	case _SC_MEMLOCK:
192 		return (_POSIX_MEMLOCK);
193 	case _SC_MEMLOCK_RANGE:
194 		return (_POSIX_MEMLOCK_RANGE);
195 	case _SC_MEMORY_PROTECTION:
196 		return (_POSIX_MEMORY_PROTECTION);
197 	case _SC_MESSAGE_PASSING:
198 #if _POSIX_MESSAGE_PASSING == 0
199 		mib[0] = CTL_P1003_1B;
200 		mib[1] = CTL_P1003_1B_MESSAGE_PASSING;
201 		goto yesno;
202 #else
203 		return (_POSIX_MESSAGE_PASSING);
204 #endif
205 	case _SC_PRIORITIZED_IO:
206 #if _POSIX_PRIORITIZED_IO == 0
207 		mib[0] = CTL_P1003_1B;
208 		mib[1] = CTL_P1003_1B_PRIORITIZED_IO;
209 		goto yesno;
210 #else
211 		return (_POSIX_PRIORITIZED_IO);
212 #endif
213 	case _SC_PRIORITY_SCHEDULING:
214 #if _POSIX_PRIORITY_SCHEDULING == 0
215 		mib[0] = CTL_P1003_1B;
216 		mib[1] = CTL_P1003_1B_PRIORITY_SCHEDULING;
217 		goto yesno;
218 #else
219 		return (_POSIX_PRIORITY_SCHEDULING);
220 #endif
221 	case _SC_REALTIME_SIGNALS:
222 #if _POSIX_REALTIME_SIGNALS == 0
223 		mib[0] = CTL_P1003_1B;
224 		mib[1] = CTL_P1003_1B_REALTIME_SIGNALS;
225 		goto yesno;
226 #else
227 		return (_POSIX_REALTIME_SIGNALS);
228 #endif
229 	case _SC_SEMAPHORES:
230 #if _POSIX_SEMAPHORES == 0
231 		mib[0] = CTL_P1003_1B;
232 		mib[1] = CTL_P1003_1B_SEMAPHORES;
233 		goto yesno;
234 #else
235 		return (_POSIX_SEMAPHORES);
236 #endif
237 	case _SC_FSYNC:
238 		return (_POSIX_FSYNC);
239 
240 	case _SC_SHARED_MEMORY_OBJECTS:
241 		return (_POSIX_SHARED_MEMORY_OBJECTS);
242 	case _SC_SYNCHRONIZED_IO:
243 #if _POSIX_SYNCHRONIZED_IO == 0
244 		mib[0] = CTL_P1003_1B;
245 		mib[1] = CTL_P1003_1B_SYNCHRONIZED_IO;
246 		goto yesno;
247 #else
248 		return (_POSIX_SYNCHRONIZED_IO);
249 #endif
250 	case _SC_TIMERS:
251 #if _POSIX_TIMERS == 0
252 		mib[0] = CTL_P1003_1B;
253 		mib[1] = CTL_P1003_1B_TIMERS;
254 		goto yesno;
255 #else
256 		return (_POSIX_TIMERS);
257 #endif
258 	case _SC_AIO_LISTIO_MAX:
259 		mib[0] = CTL_P1003_1B;
260 		mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
261 		break;
262 	case _SC_AIO_MAX:
263 		mib[0] = CTL_P1003_1B;
264 		mib[1] = CTL_P1003_1B_AIO_MAX;
265 		break;
266 	case _SC_AIO_PRIO_DELTA_MAX:
267 		mib[0] = CTL_P1003_1B;
268 		mib[1] = CTL_P1003_1B_AIO_PRIO_DELTA_MAX;
269 		break;
270 	case _SC_DELAYTIMER_MAX:
271 		mib[0] = CTL_P1003_1B;
272 		mib[1] = CTL_P1003_1B_DELAYTIMER_MAX;
273 		goto yesno;
274 	case _SC_MQ_OPEN_MAX:
275 		mib[0] = CTL_P1003_1B;
276 		mib[1] = CTL_P1003_1B_MQ_OPEN_MAX;
277 		goto yesno;
278 	case _SC_PAGESIZE:
279 		defaultresult = getpagesize();
280 		mib[0] = CTL_P1003_1B;
281 		mib[1] = CTL_P1003_1B_PAGESIZE;
282 		goto yesno;
283 	case _SC_RTSIG_MAX:
284 		mib[0] = CTL_P1003_1B;
285 		mib[1] = CTL_P1003_1B_RTSIG_MAX;
286 		goto yesno;
287 	case _SC_SEM_NSEMS_MAX:
288 		mib[0] = CTL_P1003_1B;
289 		mib[1] = CTL_P1003_1B_SEM_NSEMS_MAX;
290 		goto yesno;
291 	case _SC_SEM_VALUE_MAX:
292 		mib[0] = CTL_P1003_1B;
293 		mib[1] = CTL_P1003_1B_SEM_VALUE_MAX;
294 		goto yesno;
295 	case _SC_SIGQUEUE_MAX:
296 		mib[0] = CTL_P1003_1B;
297 		mib[1] = CTL_P1003_1B_SIGQUEUE_MAX;
298 		goto yesno;
299 	case _SC_TIMER_MAX:
300 		mib[0] = CTL_P1003_1B;
301 		mib[1] = CTL_P1003_1B_TIMER_MAX;
302 
303 yesno:		if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
304 			return (-1);
305 		if (value == 0)
306 			return (defaultresult);
307 		return (value);
308 
309 	case _SC_2_PBS:
310 	case _SC_2_PBS_ACCOUNTING:
311 	case _SC_2_PBS_CHECKPOINT:
312 	case _SC_2_PBS_LOCATE:
313 	case _SC_2_PBS_MESSAGE:
314 	case _SC_2_PBS_TRACK:
315 #if _POSIX2_PBS == 0
316 #error "don't know how to determine _SC_2_PBS"
317 		/*
318 		 * This probably requires digging through the filesystem
319 		 * to see if the appropriate package has been installed.
320 		 * Since we don't currently support this option at all,
321 		 * it's not worth the effort to write the code now.
322 		 * Figuring out which of the sub-options are supported
323 		 * would be even more difficult, so it's probably easier
324 		 * to always say ``no''.
325 		 */
326 #else
327 		return (_POSIX2_PBS);
328 #endif
329 	case _SC_ADVISORY_INFO:
330 #if _POSIX_ADVISORY_INFO == 0
331 #error "_POSIX_ADVISORY_INFO"
332 #else
333 		return (_POSIX_ADVISORY_INFO);
334 #endif
335 	case _SC_BARRIERS:
336 #if _POSIX_BARRIERS == 0
337 #error "_POSIX_BARRIERS"
338 #else
339 		return (_POSIX_BARRIERS);
340 #endif
341 	case _SC_CLOCK_SELECTION:
342 #if _POSIX_CLOCK_SELECTION == 0
343 #error "_POSIX_CLOCK_SELECTION"
344 #else
345 		return (_POSIX_CLOCK_SELECTION);
346 #endif
347 	case _SC_CPUTIME:
348 #if _POSIX_CPUTIME == 0
349 #error "_POSIX_CPUTIME"
350 #else
351 		return (_POSIX_CPUTIME);
352 #endif
353 #ifdef notdef
354 	case _SC_FILE_LOCKING:
355 		/*
356 		 * XXX - The standard doesn't tell us how to define
357 		 * _POSIX_FILE_LOCKING, so we can't answer this one.
358 		 */
359 #endif
360 #if _POSIX_THREAD_SAFE_FUNCTIONS > -1
361 	case _SC_GETGR_R_SIZE_MAX:
362 	case _SC_GETPW_R_SIZE_MAX:
363 #error "somebody needs to implement this"
364 #endif
365 	case _SC_HOST_NAME_MAX:
366 		return (MAXHOSTNAMELEN - 1); /* does not include \0 */
367 	case _SC_LOGIN_NAME_MAX:
368 		return (MAXLOGNAME);
369 	case _SC_MONOTONIC_CLOCK:
370 #if _POSIX_MONOTONIC_CLOCK == 0
371 #error "_POSIX_MONOTONIC_CLOCK"
372 #else
373 		return (_POSIX_MONOTONIC_CLOCK);
374 #endif
375 #if _POSIX_MESSAGE_PASSING > -1
376 	case _SC_MQ_PRIO_MAX:
377 		return (MQ_PRIO_MAX);
378 #endif
379 	case _SC_READER_WRITER_LOCKS:
380 		return (_POSIX_READER_WRITER_LOCKS);
381 	case _SC_REGEXP:
382 		return (_POSIX_REGEXP);
383 	case _SC_SHELL:
384 		return (_POSIX_SHELL);
385 	case _SC_SPAWN:
386 		return (_POSIX_SPAWN);
387 	case _SC_SPIN_LOCKS:
388 		return (_POSIX_SPIN_LOCKS);
389 	case _SC_SPORADIC_SERVER:
390 #if _POSIX_SPORADIC_SERVER == 0
391 #error "_POSIX_SPORADIC_SERVER"
392 #else
393 		return (_POSIX_SPORADIC_SERVER);
394 #endif
395 	case _SC_THREAD_ATTR_STACKADDR:
396 		return (_POSIX_THREAD_ATTR_STACKADDR);
397 	case _SC_THREAD_ATTR_STACKSIZE:
398 		return (_POSIX_THREAD_ATTR_STACKSIZE);
399 	case _SC_THREAD_CPUTIME:
400 		return (_POSIX_THREAD_CPUTIME);
401 	case _SC_THREAD_DESTRUCTOR_ITERATIONS:
402 		return (PTHREAD_DESTRUCTOR_ITERATIONS);
403 	case _SC_THREAD_KEYS_MAX:
404 		return (PTHREAD_KEYS_MAX);
405 	case _SC_THREAD_PRIO_INHERIT:
406 		return (_POSIX_THREAD_PRIO_INHERIT);
407 	case _SC_THREAD_PRIO_PROTECT:
408 		return (_POSIX_THREAD_PRIO_PROTECT);
409 	case _SC_THREAD_PRIORITY_SCHEDULING:
410 		return (_POSIX_THREAD_PRIORITY_SCHEDULING);
411 	case _SC_THREAD_PROCESS_SHARED:
412 		return (_POSIX_THREAD_PROCESS_SHARED);
413 	case _SC_THREAD_SAFE_FUNCTIONS:
414 		return (_POSIX_THREAD_SAFE_FUNCTIONS);
415 	case _SC_THREAD_STACK_MIN:
416 		return (PTHREAD_STACK_MIN);
417 	case _SC_THREAD_THREADS_MAX:
418 		return (PTHREAD_THREADS_MAX); /* XXX wrong type! */
419 	case _SC_TIMEOUTS:
420 		return (_POSIX_TIMEOUTS);
421 	case _SC_THREADS:
422 		return (_POSIX_THREADS);
423 	case _SC_TRACE:
424 #if _POSIX_TRACE == 0
425 #error "_POSIX_TRACE"
426 		/* While you're implementing this, also do the ones below. */
427 #else
428 		return (_POSIX_TRACE);
429 #endif
430 #if _POSIX_TRACE > -1
431 	case _SC_TRACE_EVENT_FILTER:
432 		return (_POSIX_TRACE_EVENT_FILTER);
433 	case _SC_TRACE_INHERIT:
434 		return (_POSIX_TRACE_INHERIT);
435 	case _SC_TRACE_LOG:
436 		return (_POSIX_TRACE_LOG);
437 #endif
438 	case _SC_TTY_NAME_MAX:
439 		path = _PATH_DEV;
440 		goto do_NAME_MAX;
441 	case _SC_TYPED_MEMORY_OBJECTS:
442 #if _POSIX_TYPED_MEMORY_OBJECTS == 0
443 #error "_POSIX_TYPED_MEMORY_OBJECTS"
444 #else
445 		return (_POSIX_TYPED_MEMORY_OBJECTS);
446 #endif
447 	case _SC_V6_ILP32_OFF32:
448 #if _V6_ILP32_OFF32 == 0
449 		if (sizeof(int) * CHAR_BIT == 32 &&
450 		    sizeof(int) == sizeof(long) &&
451 		    sizeof(long) == sizeof(void *) &&
452 		    sizeof(void *) == sizeof(off_t))
453 			return 1;
454 		else
455 			return -1;
456 #else
457 		return (_V6_ILP32_OFF32);
458 #endif
459 	case _SC_V6_ILP32_OFFBIG:
460 #if _V6_ILP32_OFFBIG == 0
461 		if (sizeof(int) * CHAR_BIT == 32 &&
462 		    sizeof(int) == sizeof(long) &&
463 		    sizeof(long) == sizeof(void *) &&
464 		    sizeof(off_t) * CHAR_BIT >= 64)
465 			return 1;
466 		else
467 			return -1;
468 #else
469 		return (_V6_ILP32_OFFBIG);
470 #endif
471 	case _SC_V6_LP64_OFF64:
472 #if _V6_LP64_OFF64 == 0
473 		if (sizeof(int) * CHAR_BIT == 32 &&
474 		    sizeof(long) * CHAR_BIT == 64 &&
475 		    sizeof(long) == sizeof(void *) &&
476 		    sizeof(void *) == sizeof(off_t))
477 			return 1;
478 		else
479 			return -1;
480 #else
481 		return (_V6_LP64_OFF64);
482 #endif
483 	case _SC_V6_LPBIG_OFFBIG:
484 #if _V6_LPBIG_OFFBIG == 0
485 		if (sizeof(int) * CHAR_BIT >= 32 &&
486 		    sizeof(long) * CHAR_BIT >= 64 &&
487 		    sizeof(void *) * CHAR_BIT >= 64 &&
488 		    sizeof(off_t) * CHAR_BIT >= 64)
489 			return 1;
490 		else
491 			return -1;
492 #else
493 		return (_V6_LPBIG_OFFBIG);
494 #endif
495 	case _SC_ATEXIT_MAX:
496 		return (ATEXIT_SIZE);
497 	case _SC_IOV_MAX:
498 		mib[0] = CTL_KERN;
499 		mib[1] = KERN_IOV_MAX;
500 		break;
501 	case _SC_XOPEN_CRYPT:
502 		return (_XOPEN_CRYPT);
503 	case _SC_XOPEN_ENH_I18N:
504 		return (_XOPEN_ENH_I18N);
505 	case _SC_XOPEN_LEGACY:
506 		return (_XOPEN_LEGACY);
507 	case _SC_XOPEN_REALTIME:
508 #if _XOPEN_REALTIME == 0
509 		sverrno = errno;
510 		value = sysconf(_SC_ASYNCHRONOUS_IO) > 0 &&
511 			sysconf(_SC_MEMLOCK) > 0 &&
512 			sysconf(_SC_MEMLOCK_RANGE) > 0 &&
513 			sysconf(_SC_MESSAGE_PASSING) > 0 &&
514 			sysconf(_SC_PRIORITY_SCHEDULING) > 0 &&
515 			sysconf(_SC_REALTIME_SIGNALS) > 0 &&
516 			sysconf(_SC_SEMAPHORES) > 0 &&
517 			sysconf(_SC_SHARED_MEMORY_OBJECTS) > 0 &&
518 			sysconf(_SC_SYNCHRONIZED_IO) > 0 &&
519 			sysconf(_SC_TIMERS) > 0;
520 		errno = sverrno;
521 		if (value)
522 			return (200112L);
523 		else
524 			return (-1);
525 #else
526 		return (_XOPEN_REALTIME);
527 #endif
528 	case _SC_XOPEN_REALTIME_THREADS:
529 #if _XOPEN_REALTIME_THREADS == 0
530 #error "_XOPEN_REALTIME_THREADS"
531 #else
532 		return (_XOPEN_REALTIME_THREADS);
533 #endif
534 	case _SC_XOPEN_SHM:
535 		sverrno = errno;
536 		if (sysctlbyname("kern.ipc.shmmin", &value, &len, NULL,
537 		    0) == -1) {
538 			errno = sverrno;
539 			return (-1);
540 		}
541 		errno = sverrno;
542 		return (1);
543 	case _SC_XOPEN_STREAMS:
544 		return (_XOPEN_STREAMS);
545 	case _SC_XOPEN_UNIX:
546 		return (_XOPEN_UNIX);
547 #ifdef _XOPEN_VERSION
548 	case _SC_XOPEN_VERSION:
549 		return (_XOPEN_VERSION);
550 #endif
551 #ifdef _XOPEN_XCU_VERSION
552 	case _SC_XOPEN_XCU_VERSION:
553 		return (_XOPEN_XCU_VERSION);
554 #endif
555 	case _SC_SYMLOOP_MAX:
556 		return (MAXSYMLINKS);
557 	case _SC_RAW_SOCKETS:
558 		return (_POSIX_RAW_SOCKETS);
559 	case _SC_IPV6:
560 #if _POSIX_IPV6 == 0
561 		sverrno = errno;
562 		value = socket(PF_INET6, SOCK_DGRAM, 0);
563 		errno = sverrno;
564 		if (value >= 0) {
565 			close(value);
566 			return (200112L);
567 		} else
568 			return (0);
569 #else
570 		return (_POSIX_IPV6);
571 #endif
572 
573 	case _SC_NPROCESSORS_CONF:
574 	case _SC_NPROCESSORS_ONLN:
575 		mib[0] = CTL_HW;
576 		mib[1] = HW_NCPU;
577 		break;
578 
579 #ifdef _SC_PHYS_PAGES
580 	case _SC_PHYS_PAGES:
581 		sname = "hw.availpages";
582 		break;
583 #endif
584 
585 	default:
586 		errno = EINVAL;
587 		return (-1);
588 	}
589 	if (sname == NULL) {
590 		if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
591 			value = -1;
592 	} else {
593 		if (sysctlbyname(sname, &value, &len, NULL, 0) == -1)
594 			value = -1;
595 	}
596 	return (value);
597 }
598