xref: /freebsd/lib/libc/gen/sysconf.c (revision 118063fb70c3f74f16678dc7ddbc8528c483a528)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Sean Eric Fagan of Cygnus Support.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)sysconf.c	8.2 (Berkeley) 3/20/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include "namespace.h"
42 #include <sys/param.h>
43 #include <sys/time.h>
44 #include <sys/sysctl.h>
45 #include <sys/resource.h>
46 #include <sys/socket.h>
47 
48 #include <elf.h>
49 #include <errno.h>
50 #include <limits.h>
51 #include <paths.h>
52 #include <pthread.h>		/* we just need the limits */
53 #include <semaphore.h>
54 #include <time.h>
55 #include <unistd.h>
56 #include "un-namespace.h"
57 
58 #include "../stdlib/atexit.h"
59 #include "tzfile.h"		/* from ../../../contrib/tzcode/stdtime */
60 #include "libc_private.h"
61 
62 #define	_PATH_ZONEINFO	TZDIR	/* from tzfile.h */
63 
64 /*
65  * sysconf --
66  *	get configurable system variables.
67  *
68  * XXX
69  * POSIX 1003.1 (ISO/IEC 9945-1, 4.8.1.3) states that the variable values
70  * not change during the lifetime of the calling process.  This would seem
71  * to require that any change to system limits kill all running processes.
72  * A workaround might be to cache the values when they are first retrieved
73  * and then simply return the cached value on subsequent calls.  This is
74  * less useful than returning up-to-date values, however.
75  */
76 long
77 sysconf(int name)
78 {
79 	struct rlimit rl;
80 	size_t len;
81 	int mib[2], sverrno, value;
82 	long lvalue, defaultresult;
83 	const char *path;
84 
85 	defaultresult = -1;
86 
87 	switch (name) {
88 	case _SC_ARG_MAX:
89 		mib[0] = CTL_KERN;
90 		mib[1] = KERN_ARGMAX;
91 		break;
92 	case _SC_CHILD_MAX:
93 		if (getrlimit(RLIMIT_NPROC, &rl) != 0)
94 			return (-1);
95 		if (rl.rlim_cur == RLIM_INFINITY)
96 			return (-1);
97 		if (rl.rlim_cur > LONG_MAX) {
98 			errno = EOVERFLOW;
99 			return (-1);
100 		}
101 		return ((long)rl.rlim_cur);
102 	case _SC_CLK_TCK:
103 		return (CLK_TCK);
104 	case _SC_NGROUPS_MAX:
105 		mib[0] = CTL_KERN;
106 		mib[1] = KERN_NGROUPS;
107 		break;
108 	case _SC_OPEN_MAX:
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_STREAM_MAX:
119 		if (getrlimit(RLIMIT_NOFILE, &rl) != 0)
120 			return (-1);
121 		if (rl.rlim_cur == RLIM_INFINITY)
122 			return (-1);
123 		if (rl.rlim_cur > LONG_MAX) {
124 			errno = EOVERFLOW;
125 			return (-1);
126 		}
127 		/*
128 		 * struct __sFILE currently has a limitation that
129 		 * file descriptors must fit in a signed short.
130 		 * This doesn't precisely capture the letter of POSIX
131 		 * but approximates the spirit.
132 		 */
133 		if (rl.rlim_cur > SHRT_MAX)
134 			return (SHRT_MAX);
135 
136 		return ((long)rl.rlim_cur);
137 	case _SC_JOB_CONTROL:
138 		return (_POSIX_JOB_CONTROL);
139 	case _SC_SAVED_IDS:
140 		/* XXX - must be 1 */
141 		mib[0] = CTL_KERN;
142 		mib[1] = KERN_SAVED_IDS;
143 		goto yesno;
144 	case _SC_VERSION:
145 		mib[0] = CTL_KERN;
146 		mib[1] = KERN_POSIX1;
147 		break;
148 	case _SC_BC_BASE_MAX:
149 		return (BC_BASE_MAX);
150 	case _SC_BC_DIM_MAX:
151 		return (BC_DIM_MAX);
152 	case _SC_BC_SCALE_MAX:
153 		return (BC_SCALE_MAX);
154 	case _SC_BC_STRING_MAX:
155 		return (BC_STRING_MAX);
156 	case _SC_COLL_WEIGHTS_MAX:
157 		return (COLL_WEIGHTS_MAX);
158 	case _SC_EXPR_NEST_MAX:
159 		return (EXPR_NEST_MAX);
160 	case _SC_LINE_MAX:
161 		return (LINE_MAX);
162 	case _SC_RE_DUP_MAX:
163 		return (RE_DUP_MAX);
164 	case _SC_2_VERSION:
165 		/*
166 		 * This is something of a lie, but it would be silly at
167 		 * this point to try to deduce this from the contents
168 		 * of the filesystem.
169 		 */
170 		return (_POSIX2_VERSION);
171 	case _SC_2_C_BIND:
172 		return (_POSIX2_C_BIND);
173 	case _SC_2_C_DEV:
174 		return (_POSIX2_C_DEV);
175 	case _SC_2_CHAR_TERM:
176 		return (_POSIX2_CHAR_TERM);
177 	case _SC_2_FORT_DEV:
178 		return (_POSIX2_FORT_DEV);
179 	case _SC_2_FORT_RUN:
180 		return (_POSIX2_FORT_RUN);
181 	case _SC_2_LOCALEDEF:
182 		return (_POSIX2_LOCALEDEF);
183 	case _SC_2_SW_DEV:
184 		return (_POSIX2_SW_DEV);
185 	case _SC_2_UPE:
186 		return (_POSIX2_UPE);
187 	case _SC_TZNAME_MAX:
188 		path = _PATH_ZONEINFO;
189 do_NAME_MAX:
190 		sverrno = errno;
191 		errno = 0;
192 		lvalue = pathconf(path, _PC_NAME_MAX);
193 		if (lvalue == -1 && errno != 0)
194 			return (-1);
195 		errno = sverrno;
196 		return (lvalue);
197 
198 	case _SC_ASYNCHRONOUS_IO:
199 #if _POSIX_ASYNCHRONOUS_IO == 0
200 		mib[0] = CTL_P1003_1B;
201 		mib[1] = CTL_P1003_1B_ASYNCHRONOUS_IO;
202 		break;
203 #else
204 		return (_POSIX_ASYNCHRONOUS_IO);
205 #endif
206 	case _SC_MAPPED_FILES:
207 		return (_POSIX_MAPPED_FILES);
208 	case _SC_MEMLOCK:
209 		return (_POSIX_MEMLOCK);
210 	case _SC_MEMLOCK_RANGE:
211 		return (_POSIX_MEMLOCK_RANGE);
212 	case _SC_MEMORY_PROTECTION:
213 		return (_POSIX_MEMORY_PROTECTION);
214 	case _SC_MESSAGE_PASSING:
215 #if _POSIX_MESSAGE_PASSING == 0
216 		mib[0] = CTL_P1003_1B;
217 		mib[1] = CTL_P1003_1B_MESSAGE_PASSING;
218 		goto yesno;
219 #else
220 		return (_POSIX_MESSAGE_PASSING);
221 #endif
222 	case _SC_PRIORITIZED_IO:
223 #if _POSIX_PRIORITIZED_IO == 0
224 		mib[0] = CTL_P1003_1B;
225 		mib[1] = CTL_P1003_1B_PRIORITIZED_IO;
226 		goto yesno;
227 #else
228 		return (_POSIX_PRIORITIZED_IO);
229 #endif
230 	case _SC_PRIORITY_SCHEDULING:
231 #if _POSIX_PRIORITY_SCHEDULING == 0
232 		mib[0] = CTL_P1003_1B;
233 		mib[1] = CTL_P1003_1B_PRIORITY_SCHEDULING;
234 		goto yesno;
235 #else
236 		return (_POSIX_PRIORITY_SCHEDULING);
237 #endif
238 	case _SC_REALTIME_SIGNALS:
239 #if _POSIX_REALTIME_SIGNALS == 0
240 		mib[0] = CTL_P1003_1B;
241 		mib[1] = CTL_P1003_1B_REALTIME_SIGNALS;
242 		goto yesno;
243 #else
244 		return (_POSIX_REALTIME_SIGNALS);
245 #endif
246 	case _SC_SEMAPHORES:
247 #if _POSIX_SEMAPHORES == 0
248 		mib[0] = CTL_P1003_1B;
249 		mib[1] = CTL_P1003_1B_SEMAPHORES;
250 		goto yesno;
251 #else
252 		return (_POSIX_SEMAPHORES);
253 #endif
254 	case _SC_FSYNC:
255 		return (_POSIX_FSYNC);
256 
257 	case _SC_SHARED_MEMORY_OBJECTS:
258 		return (_POSIX_SHARED_MEMORY_OBJECTS);
259 	case _SC_SYNCHRONIZED_IO:
260 #if _POSIX_SYNCHRONIZED_IO == 0
261 		mib[0] = CTL_P1003_1B;
262 		mib[1] = CTL_P1003_1B_SYNCHRONIZED_IO;
263 		goto yesno;
264 #else
265 		return (_POSIX_SYNCHRONIZED_IO);
266 #endif
267 	case _SC_TIMERS:
268 #if _POSIX_TIMERS == 0
269 		mib[0] = CTL_P1003_1B;
270 		mib[1] = CTL_P1003_1B_TIMERS;
271 		goto yesno;
272 #else
273 		return (_POSIX_TIMERS);
274 #endif
275 	case _SC_AIO_LISTIO_MAX:
276 		mib[0] = CTL_P1003_1B;
277 		mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
278 		break;
279 	case _SC_AIO_MAX:
280 		mib[0] = CTL_P1003_1B;
281 		mib[1] = CTL_P1003_1B_AIO_MAX;
282 		break;
283 	case _SC_AIO_PRIO_DELTA_MAX:
284 		mib[0] = CTL_P1003_1B;
285 		mib[1] = CTL_P1003_1B_AIO_PRIO_DELTA_MAX;
286 		break;
287 	case _SC_DELAYTIMER_MAX:
288 		mib[0] = CTL_P1003_1B;
289 		mib[1] = CTL_P1003_1B_DELAYTIMER_MAX;
290 		goto yesno;
291 	case _SC_MQ_OPEN_MAX:
292 		mib[0] = CTL_P1003_1B;
293 		mib[1] = CTL_P1003_1B_MQ_OPEN_MAX;
294 		goto yesno;
295 	case _SC_PAGESIZE:
296 		defaultresult = getpagesize();
297 		mib[0] = CTL_P1003_1B;
298 		mib[1] = CTL_P1003_1B_PAGESIZE;
299 		goto yesno;
300 	case _SC_RTSIG_MAX:
301 		mib[0] = CTL_P1003_1B;
302 		mib[1] = CTL_P1003_1B_RTSIG_MAX;
303 		goto yesno;
304 	case _SC_SEM_NSEMS_MAX:
305 		return (-1);
306 	case _SC_SEM_VALUE_MAX:
307 		return (SEM_VALUE_MAX);
308 	case _SC_SIGQUEUE_MAX:
309 		mib[0] = CTL_P1003_1B;
310 		mib[1] = CTL_P1003_1B_SIGQUEUE_MAX;
311 		goto yesno;
312 	case _SC_TIMER_MAX:
313 		mib[0] = CTL_P1003_1B;
314 		mib[1] = CTL_P1003_1B_TIMER_MAX;
315 yesno:
316 		len = sizeof(value);
317 		if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
318 			return (-1);
319 		if (value == 0)
320 			return (defaultresult);
321 		return ((long)value);
322 
323 	case _SC_2_PBS:
324 	case _SC_2_PBS_ACCOUNTING:
325 	case _SC_2_PBS_CHECKPOINT:
326 	case _SC_2_PBS_LOCATE:
327 	case _SC_2_PBS_MESSAGE:
328 	case _SC_2_PBS_TRACK:
329 #if _POSIX2_PBS == 0
330 #error "don't know how to determine _SC_2_PBS"
331 		/*
332 		 * This probably requires digging through the filesystem
333 		 * to see if the appropriate package has been installed.
334 		 * Since we don't currently support this option at all,
335 		 * it's not worth the effort to write the code now.
336 		 * Figuring out which of the sub-options are supported
337 		 * would be even more difficult, so it's probably easier
338 		 * to always say ``no''.
339 		 */
340 #else
341 		return (_POSIX2_PBS);
342 #endif
343 	case _SC_ADVISORY_INFO:
344 #if _POSIX_ADVISORY_INFO == 0
345 #error "_POSIX_ADVISORY_INFO"
346 #else
347 		return (_POSIX_ADVISORY_INFO);
348 #endif
349 	case _SC_BARRIERS:
350 #if _POSIX_BARRIERS == 0
351 #error "_POSIX_BARRIERS"
352 #else
353 		return (_POSIX_BARRIERS);
354 #endif
355 	case _SC_CLOCK_SELECTION:
356 #if _POSIX_CLOCK_SELECTION == 0
357 #error "_POSIX_CLOCK_SELECTION"
358 #else
359 		return (_POSIX_CLOCK_SELECTION);
360 #endif
361 	case _SC_CPUTIME:
362 		return (_POSIX_CPUTIME);
363 #ifdef notdef
364 	case _SC_FILE_LOCKING:
365 		/*
366 		 * XXX - The standard doesn't tell us how to define
367 		 * _POSIX_FILE_LOCKING, so we can't answer this one.
368 		 */
369 #endif
370 
371 	/*
372 	 * SUSv4tc1 says the following about _SC_GETGR_R_SIZE_MAX and
373 	 * _SC_GETPW_R_SIZE_MAX:
374 	 * Note that sysconf(_SC_GETGR_R_SIZE_MAX) may return -1 if
375 	 * there is no hard limit on the size of the buffer needed to
376 	 * store all the groups returned.
377 	 */
378 	case _SC_GETGR_R_SIZE_MAX:
379 	case _SC_GETPW_R_SIZE_MAX:
380 		return (-1);
381 	case _SC_HOST_NAME_MAX:
382 		return (MAXHOSTNAMELEN - 1); /* does not include \0 */
383 	case _SC_LOGIN_NAME_MAX:
384 		return (MAXLOGNAME);
385 	case _SC_MONOTONIC_CLOCK:
386 #if _POSIX_MONOTONIC_CLOCK == 0
387 #error "_POSIX_MONOTONIC_CLOCK"
388 #else
389 		return (_POSIX_MONOTONIC_CLOCK);
390 #endif
391 #if _POSIX_MESSAGE_PASSING > -1
392 	case _SC_MQ_PRIO_MAX:
393 		return (MQ_PRIO_MAX);
394 #endif
395 	case _SC_READER_WRITER_LOCKS:
396 		return (_POSIX_READER_WRITER_LOCKS);
397 	case _SC_REGEXP:
398 		return (_POSIX_REGEXP);
399 	case _SC_SHELL:
400 		return (_POSIX_SHELL);
401 	case _SC_SPAWN:
402 		return (_POSIX_SPAWN);
403 	case _SC_SPIN_LOCKS:
404 		return (_POSIX_SPIN_LOCKS);
405 	case _SC_SPORADIC_SERVER:
406 #if _POSIX_SPORADIC_SERVER == 0
407 #error "_POSIX_SPORADIC_SERVER"
408 #else
409 		return (_POSIX_SPORADIC_SERVER);
410 #endif
411 	case _SC_THREAD_ATTR_STACKADDR:
412 		return (_POSIX_THREAD_ATTR_STACKADDR);
413 	case _SC_THREAD_ATTR_STACKSIZE:
414 		return (_POSIX_THREAD_ATTR_STACKSIZE);
415 	case _SC_THREAD_CPUTIME:
416 		return (_POSIX_THREAD_CPUTIME);
417 	case _SC_THREAD_DESTRUCTOR_ITERATIONS:
418 		return (PTHREAD_DESTRUCTOR_ITERATIONS);
419 	case _SC_THREAD_KEYS_MAX:
420 		return (PTHREAD_KEYS_MAX);
421 	case _SC_THREAD_PRIO_INHERIT:
422 		return (_POSIX_THREAD_PRIO_INHERIT);
423 	case _SC_THREAD_PRIO_PROTECT:
424 		return (_POSIX_THREAD_PRIO_PROTECT);
425 	case _SC_THREAD_PRIORITY_SCHEDULING:
426 		return (_POSIX_THREAD_PRIORITY_SCHEDULING);
427 	case _SC_THREAD_PROCESS_SHARED:
428 		return (_POSIX_THREAD_PROCESS_SHARED);
429 	case _SC_THREAD_SAFE_FUNCTIONS:
430 		return (_POSIX_THREAD_SAFE_FUNCTIONS);
431 	case _SC_THREAD_STACK_MIN:
432 		return (PTHREAD_STACK_MIN);
433 	case _SC_THREAD_THREADS_MAX:
434 		return (PTHREAD_THREADS_MAX); /* XXX wrong type! */
435 	case _SC_TIMEOUTS:
436 		return (_POSIX_TIMEOUTS);
437 	case _SC_THREADS:
438 		return (_POSIX_THREADS);
439 	case _SC_TRACE:
440 #if _POSIX_TRACE == 0
441 #error "_POSIX_TRACE"
442 		/* While you're implementing this, also do the ones below. */
443 #else
444 		return (_POSIX_TRACE);
445 #endif
446 #if _POSIX_TRACE > -1
447 	case _SC_TRACE_EVENT_FILTER:
448 		return (_POSIX_TRACE_EVENT_FILTER);
449 	case _SC_TRACE_INHERIT:
450 		return (_POSIX_TRACE_INHERIT);
451 	case _SC_TRACE_LOG:
452 		return (_POSIX_TRACE_LOG);
453 #endif
454 	case _SC_TTY_NAME_MAX:
455 		path = _PATH_DEV;
456 		goto do_NAME_MAX;
457 	case _SC_TYPED_MEMORY_OBJECTS:
458 #if _POSIX_TYPED_MEMORY_OBJECTS == 0
459 #error "_POSIX_TYPED_MEMORY_OBJECTS"
460 #else
461 		return (_POSIX_TYPED_MEMORY_OBJECTS);
462 #endif
463 	case _SC_V6_ILP32_OFF32:
464 #if _V6_ILP32_OFF32 == 0
465 		if (sizeof(int) * CHAR_BIT == 32 &&
466 		    sizeof(int) == sizeof(long) &&
467 		    sizeof(long) == sizeof(void *) &&
468 		    sizeof(void *) == sizeof(off_t))
469 			return 1;
470 		else
471 			return -1;
472 #else
473 		return (_V6_ILP32_OFF32);
474 #endif
475 	case _SC_V6_ILP32_OFFBIG:
476 #if _V6_ILP32_OFFBIG == 0
477 		if (sizeof(int) * CHAR_BIT == 32 &&
478 		    sizeof(int) == sizeof(long) &&
479 		    sizeof(long) == sizeof(void *) &&
480 		    sizeof(off_t) * CHAR_BIT >= 64)
481 			return 1;
482 		else
483 			return -1;
484 #else
485 		return (_V6_ILP32_OFFBIG);
486 #endif
487 	case _SC_V6_LP64_OFF64:
488 #if _V6_LP64_OFF64 == 0
489 		if (sizeof(int) * CHAR_BIT == 32 &&
490 		    sizeof(long) * CHAR_BIT == 64 &&
491 		    sizeof(long) == sizeof(void *) &&
492 		    sizeof(void *) == sizeof(off_t))
493 			return 1;
494 		else
495 			return -1;
496 #else
497 		return (_V6_LP64_OFF64);
498 #endif
499 	case _SC_V6_LPBIG_OFFBIG:
500 #if _V6_LPBIG_OFFBIG == 0
501 		if (sizeof(int) * CHAR_BIT >= 32 &&
502 		    sizeof(long) * CHAR_BIT >= 64 &&
503 		    sizeof(void *) * CHAR_BIT >= 64 &&
504 		    sizeof(off_t) * CHAR_BIT >= 64)
505 			return 1;
506 		else
507 			return -1;
508 #else
509 		return (_V6_LPBIG_OFFBIG);
510 #endif
511 	case _SC_ATEXIT_MAX:
512 		return (ATEXIT_SIZE);
513 	case _SC_IOV_MAX:
514 		mib[0] = CTL_KERN;
515 		mib[1] = KERN_IOV_MAX;
516 		break;
517 	case _SC_XOPEN_CRYPT:
518 		return (_XOPEN_CRYPT);
519 	case _SC_XOPEN_ENH_I18N:
520 		return (_XOPEN_ENH_I18N);
521 	case _SC_XOPEN_LEGACY:
522 		return (_XOPEN_LEGACY);
523 	case _SC_XOPEN_REALTIME:
524 #if _XOPEN_REALTIME == 0
525 		sverrno = errno;
526 		value = sysconf(_SC_ASYNCHRONOUS_IO) > 0 &&
527 			sysconf(_SC_MEMLOCK) > 0 &&
528 			sysconf(_SC_MEMLOCK_RANGE) > 0 &&
529 			sysconf(_SC_MESSAGE_PASSING) > 0 &&
530 			sysconf(_SC_PRIORITY_SCHEDULING) > 0 &&
531 			sysconf(_SC_REALTIME_SIGNALS) > 0 &&
532 			sysconf(_SC_SEMAPHORES) > 0 &&
533 			sysconf(_SC_SHARED_MEMORY_OBJECTS) > 0 &&
534 			sysconf(_SC_SYNCHRONIZED_IO) > 0 &&
535 			sysconf(_SC_TIMERS) > 0;
536 		errno = sverrno;
537 		if (value)
538 			return (200112L);
539 		else
540 			return (-1);
541 #else
542 		return (_XOPEN_REALTIME);
543 #endif
544 	case _SC_XOPEN_REALTIME_THREADS:
545 #if _XOPEN_REALTIME_THREADS == 0
546 #error "_XOPEN_REALTIME_THREADS"
547 #else
548 		return (_XOPEN_REALTIME_THREADS);
549 #endif
550 	case _SC_XOPEN_SHM:
551 		len = sizeof(lvalue);
552 		sverrno = errno;
553 		if (sysctlbyname("kern.ipc.shmmin", &lvalue, &len, NULL,
554 		    0) == -1) {
555 			errno = sverrno;
556 			return (-1);
557 		}
558 		errno = sverrno;
559 		return (1);
560 	case _SC_XOPEN_STREAMS:
561 		return (_XOPEN_STREAMS);
562 	case _SC_XOPEN_UNIX:
563 		return (_XOPEN_UNIX);
564 #ifdef _XOPEN_VERSION
565 	case _SC_XOPEN_VERSION:
566 		return (_XOPEN_VERSION);
567 #endif
568 #ifdef _XOPEN_XCU_VERSION
569 	case _SC_XOPEN_XCU_VERSION:
570 		return (_XOPEN_XCU_VERSION);
571 #endif
572 	case _SC_SYMLOOP_MAX:
573 		return (MAXSYMLINKS);
574 	case _SC_RAW_SOCKETS:
575 		return (_POSIX_RAW_SOCKETS);
576 	case _SC_IPV6:
577 #if _POSIX_IPV6 == 0
578 		sverrno = errno;
579 		value = _socket(PF_INET6, SOCK_DGRAM, 0);
580 		errno = sverrno;
581 		if (value >= 0) {
582 			_close(value);
583 			return (200112L);
584 		} else
585 			return (0);
586 #else
587 		return (_POSIX_IPV6);
588 #endif
589 
590 	case _SC_NPROCESSORS_CONF:
591 	case _SC_NPROCESSORS_ONLN:
592 		if (_elf_aux_info(AT_NCPUS, &value, sizeof(value)) == 0)
593 			return ((long)value);
594 		mib[0] = CTL_HW;
595 		mib[1] = HW_NCPU;
596 		break;
597 
598 #ifdef _SC_PHYS_PAGES
599 	case _SC_PHYS_PAGES:
600 		len = sizeof(lvalue);
601 		if (sysctlbyname("hw.availpages", &lvalue, &len, NULL, 0) == -1)
602 			return (-1);
603 		return (lvalue);
604 #endif
605 
606 #ifdef _SC_CPUSET_SIZE
607 	case _SC_CPUSET_SIZE:
608 		len = sizeof(value);
609 		if (sysctlbyname("kern.sched.cpusetsize", &value, &len, NULL,
610 		    0) == -1)
611 			return (-1);
612 		return ((long)value);
613 #endif
614 
615 	default:
616 		errno = EINVAL;
617 		return (-1);
618 	}
619 	len = sizeof(value);
620 	if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
621 		value = -1;
622 	return ((long)value);
623 }
624