lib/libc/gen/sysconf.c

   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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#)sysconf.c        8.2 (Berkeley) 3/20/94
  33  * $FreeBSD: src/lib/libc/gen/sysconf.c,v 1.26 2008/02/27 05:56:57 wollman Exp $
  34  * $DragonFly: src/lib/libc/gen/sysconf.c,v 1.5 2008/02/21 12:47:54 hasso Exp $
  35  */
  36
  37 #include <sys/param.h>
  38 #include <sys/time.h>
  39 #include <sys/sysctl.h>
  40 #include <sys/resource.h>
  41 #include <sys/socket.h>
  42
  43 #include <errno.h>
  44 #include <limits.h>
  45 #include <paths.h>
  46 #include <pthread.h>            /* we just need the limits */
  47 #include <time.h>
  48 #include <unistd.h>
  49
  50 #include "../stdlib/atexit.h"
  51 #include "../stdtime/tzfile.h"
  52
  53 #define _PATH_ZONEINFO  TZDIR   /* from tzfile.h */
  54
  55 /*
  56  * sysconf --
  57  *      get configurable system variables.
  58  *
  59  * XXX
  60  * POSIX 1003.1 (ISO/IEC 9945-1, 4.8.1.3) states that the variable values
  61  * not change during the lifetime of the calling process.  This would seem
  62  * to require that any change to system limits kill all running processes.
  63  * A workaround might be to cache the values when they are first retrieved
  64  * and then simply return the cached value on subsequent calls.  This is
  65  * less useful than returning up-to-date values, however.
  66  */
  67 long
  68 sysconf(int name)
  69 {
  70         struct rlimit rl;
  71         size_t len;
  72         int mib[2], sverrno, value;
  73         long lvalue, defaultresult;
  74         const char *path;
  75
  76         defaultresult = -1;
  77
  78         switch (name) {
  79         case _SC_ARG_MAX:
  80                 mib[0] = CTL_KERN;
  81                 mib[1] = KERN_ARGMAX;
  82                 break;
  83         case _SC_CHILD_MAX:
  84                 if (getrlimit(RLIMIT_NPROC, &rl) != 0)
  85                         return (-1);
  86                 if (rl.rlim_cur == RLIM_INFINITY)
  87                         return (-1);
  88                 if (rl.rlim_cur > LONG_MAX) {
  89                         errno = EOVERFLOW;
  90                         return (-1);
  91                 }
  92                 return ((long)rl.rlim_cur);
  93         case _SC_CLK_TCK:
  94                 return (CLK_TCK);
  95         case _SC_NGROUPS_MAX:
  96                 mib[0] = CTL_KERN;
  97                 mib[1] = KERN_NGROUPS;
  98                 break;
  99         case _SC_OPEN_MAX:
 100                 if (getrlimit(RLIMIT_NOFILE, &rl) != 0)
 101                         return (-1);
 102                 if (rl.rlim_cur == RLIM_INFINITY)
 103                         return (-1);
 104                 if (rl.rlim_cur > LONG_MAX) {
 105                         errno = EOVERFLOW;
 106                         return (-1);
 107                 }
 108                 return ((long)rl.rlim_cur);
 109         case _SC_STREAM_MAX:
 110                 if (getrlimit(RLIMIT_NOFILE, &rl) != 0)
 111                         return (-1);
 112                 if (rl.rlim_cur == RLIM_INFINITY)
 113                         return (-1);
 114                 if (rl.rlim_cur > LONG_MAX) {
 115                         errno = EOVERFLOW;
 116                         return (-1);
 117                 }
 118                 /*
 119                  * struct __sFILE currently has a limitation that
 120                  * file descriptors must fit in a signed short.
 121                  * This doesn't precisely capture the letter of POSIX
 122                  * but approximates the spirit.
 123                  */
 124                 if (rl.rlim_cur > SHRT_MAX)
 125                         return (SHRT_MAX);
 126
 127                 return ((long)rl.rlim_cur);
 128         case _SC_JOB_CONTROL:
 129                 return (_POSIX_JOB_CONTROL);
 130         case _SC_SAVED_IDS:
 131                 /* XXX - must be 1 */
 132                 mib[0] = CTL_KERN;
 133                 mib[1] = KERN_SAVED_IDS;
 134                 goto yesno;
 135         case _SC_VERSION:
 136                 mib[0] = CTL_KERN;
 137                 mib[1] = KERN_POSIX1;
 138                 break;
 139         case _SC_BC_BASE_MAX:
 140                 return (BC_BASE_MAX);
 141         case _SC_BC_DIM_MAX:
 142                 return (BC_DIM_MAX);
 143         case _SC_BC_SCALE_MAX:
 144                 return (BC_SCALE_MAX);
 145         case _SC_BC_STRING_MAX:
 146                 return (BC_STRING_MAX);
 147         case _SC_COLL_WEIGHTS_MAX:
 148                 return (COLL_WEIGHTS_MAX);
 149         case _SC_EXPR_NEST_MAX:
 150                 return (EXPR_NEST_MAX);
 151         case _SC_LINE_MAX:
 152                 return (LINE_MAX);
 153         case _SC_RE_DUP_MAX:
 154                 return (RE_DUP_MAX);
 155         case _SC_2_VERSION:
 156                 /*
 157                  * This is something of a lie, but it would be silly at
 158                  * this point to try to deduce this from the contents
 159                  * of the filesystem.
 160                  */
 161                 return (_POSIX2_VERSION);
 162         case _SC_2_C_BIND:
 163                 return (_POSIX2_C_BIND);
 164         case _SC_2_C_DEV:
 165                 return (_POSIX2_C_DEV);
 166         case _SC_2_CHAR_TERM:
 167                 return (_POSIX2_CHAR_TERM);
 168         case _SC_2_FORT_DEV:
 169                 return (_POSIX2_FORT_DEV);
 170         case _SC_2_FORT_RUN:
 171                 return (_POSIX2_FORT_RUN);
 172         case _SC_2_LOCALEDEF:
 173                 return (_POSIX2_LOCALEDEF);
 174         case _SC_2_SW_DEV:
 175                 return (_POSIX2_SW_DEV);
 176         case _SC_2_UPE:
 177                 return (_POSIX2_UPE);
 178         case _SC_TZNAME_MAX:
 179                 path = _PATH_ZONEINFO;
 180 do_NAME_MAX:
 181                 sverrno = errno;
 182                 errno = 0;
 183                 lvalue = pathconf(path, _PC_NAME_MAX);
 184                 if (lvalue == -1 && errno != 0)
 185                         return (-1);
 186                 errno = sverrno;
 187                 return (lvalue);
 188
 189         case _SC_ASYNCHRONOUS_IO:
 190 #if _POSIX_ASYNCHRONOUS_IO == 0
 191                 mib[0] = CTL_P1003_1B;
 192                 mib[1] = CTL_P1003_1B_ASYNCHRONOUS_IO;
 193                 break;
 194 #else
 195                 return (_POSIX_ASYNCHRONOUS_IO);
 196 #endif
 197         case _SC_MAPPED_FILES:
 198                 return (_POSIX_MAPPED_FILES);
 199         case _SC_MEMLOCK:
 200                 return (_POSIX_MEMLOCK);
 201         case _SC_MEMLOCK_RANGE:
 202                 return (_POSIX_MEMLOCK_RANGE);
 203         case _SC_MEMORY_PROTECTION:
 204                 return (_POSIX_MEMORY_PROTECTION);
 205         case _SC_MESSAGE_PASSING:
 206 #if _POSIX_MESSAGE_PASSING == 0
 207                 mib[0] = CTL_P1003_1B;
 208                 mib[1] = CTL_P1003_1B_MESSAGE_PASSING;
 209                 goto yesno;
 210 #else
 211                 return (_POSIX_MESSAGE_PASSING);
 212 #endif
 213         case _SC_PRIORITIZED_IO:
 214 #if _POSIX_PRIORITIZED_IO == 0
 215                 mib[0] = CTL_P1003_1B;
 216                 mib[1] = CTL_P1003_1B_PRIORITIZED_IO;
 217                 goto yesno;
 218 #else
 219                 return (_POSIX_PRIORITIZED_IO);
 220 #endif
 221         case _SC_PRIORITY_SCHEDULING:
 222 #if _POSIX_PRIORITY_SCHEDULING == 0
 223                 mib[0] = CTL_P1003_1B;
 224                 mib[1] = CTL_P1003_1B_PRIORITY_SCHEDULING;
 225                 goto yesno;
 226 #else
 227                 return (_POSIX_PRIORITY_SCHEDULING);
 228 #endif
 229         case _SC_REALTIME_SIGNALS:
 230 #if _POSIX_REALTIME_SIGNALS == 0
 231                 mib[0] = CTL_P1003_1B;
 232                 mib[1] = CTL_P1003_1B_REALTIME_SIGNALS;
 233                 goto yesno;
 234 #else
 235                 return (_POSIX_REALTIME_SIGNALS);
 236 #endif
 237         case _SC_SEMAPHORES:
 238 #if _POSIX_SEMAPHORES == 0
 239                 mib[0] = CTL_P1003_1B;
 240                 mib[1] = CTL_P1003_1B_SEMAPHORES;
 241                 goto yesno;
 242 #else
 243                 return (_POSIX_SEMAPHORES);
 244 #endif
 245         case _SC_FSYNC:
 246                 return (_POSIX_FSYNC);
 247
 248         case _SC_SHARED_MEMORY_OBJECTS:
 249                 return (_POSIX_SHARED_MEMORY_OBJECTS);
 250         case _SC_SYNCHRONIZED_IO:
 251 #if _POSIX_SYNCHRONIZED_IO == 0
 252                 mib[0] = CTL_P1003_1B;
 253                 mib[1] = CTL_P1003_1B_SYNCHRONIZED_IO;
 254                 goto yesno;
 255 #else
 256                 return (_POSIX_SYNCHRONIZED_IO);
 257 #endif
 258         case _SC_TIMERS:
 259 #if _POSIX_TIMERS == 0
 260                 mib[0] = CTL_P1003_1B;
 261                 mib[1] = CTL_P1003_1B_TIMERS;
 262                 goto yesno;
 263 #else
 264                 return (_POSIX_TIMERS);
 265 #endif
 266         case _SC_AIO_LISTIO_MAX:
 267                 mib[0] = CTL_P1003_1B;
 268                 mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
 269                 break;
 270         case _SC_AIO_MAX:
 271                 mib[0] = CTL_P1003_1B;
 272                 mib[1] = CTL_P1003_1B_AIO_MAX;
 273                 break;
 274         case _SC_AIO_PRIO_DELTA_MAX:
 275                 mib[0] = CTL_P1003_1B;
 276                 mib[1] = CTL_P1003_1B_AIO_PRIO_DELTA_MAX;
 277                 break;
 278         case _SC_DELAYTIMER_MAX:
 279                 mib[0] = CTL_P1003_1B;
 280                 mib[1] = CTL_P1003_1B_DELAYTIMER_MAX;
 281                 goto yesno;
 282         case _SC_MQ_OPEN_MAX:
 283                 mib[0] = CTL_P1003_1B;
 284                 mib[1] = CTL_P1003_1B_MQ_OPEN_MAX;
 285                 goto yesno;
 286         case _SC_PAGESIZE:
 287                 defaultresult = getpagesize();
 288                 mib[0] = CTL_P1003_1B;
 289                 mib[1] = CTL_P1003_1B_PAGESIZE;
 290                 goto yesno;
 291         case _SC_RTSIG_MAX:
 292                 mib[0] = CTL_P1003_1B;
 293                 mib[1] = CTL_P1003_1B_RTSIG_MAX;
 294                 goto yesno;
 295         case _SC_SEM_NSEMS_MAX:
 296                 mib[0] = CTL_P1003_1B;
 297                 mib[1] = CTL_P1003_1B_SEM_NSEMS_MAX;
 298                 goto yesno;
 299         case _SC_SEM_VALUE_MAX:
 300                 mib[0] = CTL_P1003_1B;
 301                 mib[1] = CTL_P1003_1B_SEM_VALUE_MAX;
 302                 goto yesno;
 303         case _SC_SIGQUEUE_MAX:
 304                 mib[0] = CTL_P1003_1B;
 305                 mib[1] = CTL_P1003_1B_SIGQUEUE_MAX;
 306                 goto yesno;
 307         case _SC_TIMER_MAX:
 308                 mib[0] = CTL_P1003_1B;
 309                 mib[1] = CTL_P1003_1B_TIMER_MAX;
 310 yesno:
 311                 len = sizeof(value);
 312                 if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
 313                         return (-1);
 314                 if (value == 0)
 315                         return (defaultresult);
 316                 return ((long)value);
 317
 318         case _SC_2_PBS:
 319         case _SC_2_PBS_ACCOUNTING:
 320         case _SC_2_PBS_CHECKPOINT:
 321         case _SC_2_PBS_LOCATE:
 322         case _SC_2_PBS_MESSAGE:
 323         case _SC_2_PBS_TRACK:
 324 #if _POSIX2_PBS == 0
 325 #error "don't know how to determine _SC_2_PBS"
 326                 /*
 327                  * This probably requires digging through the filesystem
 328                  * to see if the appropriate package has been installed.
 329                  * Since we don't currently support this option at all,
 330                  * it's not worth the effort to write the code now.
 331                  * Figuring out which of the sub-options are supported
 332                  * would be even more difficult, so it's probably easier
 333                  * to always say ``no''.
 334                  */
 335 #else
 336                 return (_POSIX2_PBS);
 337 #endif
 338         case _SC_ADVISORY_INFO:
 339 #if _POSIX_ADVISORY_INFO == 0
 340 #error "_POSIX_ADVISORY_INFO"
 341 #else
 342                 return (_POSIX_ADVISORY_INFO);
 343 #endif
 344 #if 0
 345         case _SC_BARRIERS:
 346 #if _POSIX_BARRIERS == 0
 347 #error "_POSIX_BARRIERS"
 348 #else
 349                 return (_POSIX_BARRIERS);
 350 #endif
 351 #endif
 352         case _SC_CLOCK_SELECTION:
 353 #if _POSIX_CLOCK_SELECTION == 0
 354 #error "_POSIX_CLOCK_SELECTION"
 355 #else
 356                 return (_POSIX_CLOCK_SELECTION);
 357 #endif
 358         case _SC_CPUTIME:
 359 #if _POSIX_CPUTIME == 0
 360 #error "_POSIX_CPUTIME"
 361 #else
 362                 return (_POSIX_CPUTIME);
 363 #endif
 364 #ifdef notdef
 365         case _SC_FILE_LOCKING:
 366                 /*
 367                  * XXX - The standard doesn't tell us how to define
 368                  * _POSIX_FILE_LOCKING, so we can't answer this one.
 369                  */
 370 #endif
 371 #if _POSIX_THREAD_SAFE_FUNCTIONS > -1
 372         case _SC_GETGR_R_SIZE_MAX:
 373         case _SC_GETPW_R_SIZE_MAX:
 374 #error "somebody needs to implement this"
 375 #endif
 376         case _SC_HOST_NAME_MAX:
 377                 return (MAXHOSTNAMELEN - 1); /* does not include \0 */
 378         case _SC_LOGIN_NAME_MAX:
 379                 return (MAXLOGNAME);
 380         case _SC_MONOTONIC_CLOCK:
 381 #if _POSIX_MONOTONIC_CLOCK == 0
 382 #error "_POSIX_MONOTONIC_CLOCK"
 383 #else
 384                 return (_POSIX_MONOTONIC_CLOCK);
 385 #endif
 386 #if _POSIX_MESSAGE_PASSING > -1
 387         case _SC_MQ_PRIO_MAX:
 388                 return (MQ_PRIO_MAX);
 389 #endif
 390         case _SC_READER_WRITER_LOCKS:
 391                 return (_POSIX_READER_WRITER_LOCKS);
 392         case _SC_REGEXP:
 393                 return (_POSIX_REGEXP);
 394         case _SC_SHELL:
 395                 return (_POSIX_SHELL);
 396         case _SC_SPAWN:
 397                 return (_POSIX_SPAWN);
 398 #if 0
 399         case _SC_SPIN_LOCKS:
 400                 return (_POSIX_SPIN_LOCKS);
 401 #endif
 402         case _SC_SPORADIC_SERVER:
 403 #if _POSIX_SPORADIC_SERVER == 0
 404 #error "_POSIX_SPORADIC_SERVER"
 405 #else
 406                 return (_POSIX_SPORADIC_SERVER);
 407 #endif
 408         case _SC_THREAD_ATTR_STACKADDR:
 409                 return (_POSIX_THREAD_ATTR_STACKADDR);
 410         case _SC_THREAD_ATTR_STACKSIZE:
 411                 return (_POSIX_THREAD_ATTR_STACKSIZE);
 412         case _SC_THREAD_CPUTIME:
 413                 return (_POSIX_THREAD_CPUTIME);
 414         case _SC_THREAD_DESTRUCTOR_ITERATIONS:
 415                 return (PTHREAD_DESTRUCTOR_ITERATIONS);
 416         case _SC_THREAD_KEYS_MAX:
 417                 return (PTHREAD_KEYS_MAX);
 418         case _SC_THREAD_PRIO_INHERIT:
 419                 return (_POSIX_THREAD_PRIO_INHERIT);
 420         case _SC_THREAD_PRIO_PROTECT:
 421                 return (_POSIX_THREAD_PRIO_PROTECT);
 422         case _SC_THREAD_PRIORITY_SCHEDULING:
 423                 return (_POSIX_THREAD_PRIORITY_SCHEDULING);
 424         case _SC_THREAD_PROCESS_SHARED:
 425                 return (_POSIX_THREAD_PROCESS_SHARED);
 426         case _SC_THREAD_SAFE_FUNCTIONS:
 427                 return (_POSIX_THREAD_SAFE_FUNCTIONS);
 428         case _SC_THREAD_STACK_MIN:
 429                 return (PTHREAD_STACK_MIN);
 430         case _SC_THREAD_THREADS_MAX:
 431                 return (PTHREAD_THREADS_MAX); /* XXX wrong type! */
 432         case _SC_TIMEOUTS:
 433                 return (_POSIX_TIMEOUTS);
 434         case _SC_THREADS:
 435                 return (_POSIX_THREADS);
 436         case _SC_TRACE:
 437 #if _POSIX_TRACE == 0
 438 #error "_POSIX_TRACE"
 439                 /* While you're implementing this, also do the ones below. */
 440 #else
 441                 return (_POSIX_TRACE);
 442 #endif
 443 #if _POSIX_TRACE > -1
 444         case _SC_TRACE_EVENT_FILTER:
 445                 return (_POSIX_TRACE_EVENT_FILTER);
 446         case _SC_TRACE_INHERIT:
 447                 return (_POSIX_TRACE_INHERIT);
 448         case _SC_TRACE_LOG:
 449                 return (_POSIX_TRACE_LOG);
 450 #endif
 451         case _SC_TTY_NAME_MAX:
 452                 path = _PATH_DEV;
 453                 goto do_NAME_MAX;
 454         case _SC_TYPED_MEMORY_OBJECTS:
 455 #if _POSIX_TYPED_MEMORY_OBJECTS == 0
 456 #error "_POSIX_TYPED_MEMORY_OBJECTS"
 457 #else
 458                 return (_POSIX_TYPED_MEMORY_OBJECTS);
 459 #endif
 460         case _SC_V6_ILP32_OFF32:
 461 #if _V6_ILP32_OFF32 == 0
 462                 if (sizeof(int) * CHAR_BIT == 32 &&
 463                     sizeof(int) == sizeof(long) &&
 464                     sizeof(long) == sizeof(void *) &&
 465                     sizeof(void *) == sizeof(off_t))
 466                         return 1;
 467                 else
 468                         return -1;
 469 #else
 470                 return (_V6_ILP32_OFF32);
 471 #endif
 472         case _SC_V6_ILP32_OFFBIG:
 473 #if _V6_ILP32_OFFBIG == 0
 474                 if (sizeof(int) * CHAR_BIT == 32 &&
 475                     sizeof(int) == sizeof(long) &&
 476                     sizeof(long) == sizeof(void *) &&
 477                     sizeof(off_t) * CHAR_BIT >= 64)
 478                         return 1;
 479                 else
 480                         return -1;
 481 #else
 482                 return (_V6_ILP32_OFFBIG);
 483 #endif
 484         case _SC_V6_LP64_OFF64:
 485 #if _V6_LP64_OFF64 == 0
 486                 if (sizeof(int) * CHAR_BIT == 32 &&
 487                     sizeof(long) * CHAR_BIT == 64 &&
 488                     sizeof(long) == sizeof(void *) &&
 489                     sizeof(void *) == sizeof(off_t))
 490                         return 1;
 491                 else
 492                         return -1;
 493 #else
 494                 return (_V6_LP64_OFF64);
 495 #endif
 496         case _SC_V6_LPBIG_OFFBIG:
 497 #if _V6_LPBIG_OFFBIG == 0
 498                 if (sizeof(int) * CHAR_BIT >= 32 &&
 499                     sizeof(long) * CHAR_BIT >= 64 &&
 500                     sizeof(void *) * CHAR_BIT >= 64 &&
 501                     sizeof(off_t) * CHAR_BIT >= 64)
 502                         return 1;
 503                 else
 504                         return -1;
 505 #else
 506                 return (_V6_LPBIG_OFFBIG);
 507 #endif
 508         case _SC_ATEXIT_MAX:
 509                 return (ATEXIT_SIZE);
 510         case _SC_IOV_MAX:
 511                 mib[0] = CTL_KERN;
 512                 mib[1] = KERN_IOV_MAX;
 513                 break;
 514         case _SC_XOPEN_CRYPT:
 515                 return (_XOPEN_CRYPT);
 516         case _SC_XOPEN_ENH_I18N:
 517                 return (_XOPEN_ENH_I18N);
 518         case _SC_XOPEN_LEGACY:
 519                 return (_XOPEN_LEGACY);
 520         case _SC_XOPEN_REALTIME:
 521 #if _XOPEN_REALTIME == 0
 522                 sverrno = errno;
 523                 value = sysconf(_SC_ASYNCHRONOUS_IO) > 0 &&
 524                         sysconf(_SC_MEMLOCK) > 0 &&
 525                         sysconf(_SC_MEMLOCK_RANGE) > 0 &&
 526                         sysconf(_SC_MESSAGE_PASSING) > 0 &&
 527                         sysconf(_SC_PRIORITY_SCHEDULING) > 0 &&
 528                         sysconf(_SC_REALTIME_SIGNALS) > 0 &&
 529                         sysconf(_SC_SEMAPHORES) > 0 &&
 530                         sysconf(_SC_SHARED_MEMORY_OBJECTS) > 0 &&
 531                         sysconf(_SC_SYNCHRONIZED_IO) > 0 &&
 532                         sysconf(_SC_TIMERS) > 0;
 533                 errno = sverrno;
 534                 if (value)
 535                         return (200112L);
 536                 else
 537                         return (-1);
 538 #else
 539                 return (_XOPEN_REALTIME);
 540 #endif
 541         case _SC_XOPEN_REALTIME_THREADS:
 542 #if _XOPEN_REALTIME_THREADS == 0
 543 #error "_XOPEN_REALTIME_THREADS"
 544 #else
 545                 return (_XOPEN_REALTIME_THREADS);
 546 #endif
 547         case _SC_XOPEN_SHM:
 548                 len = sizeof(lvalue);
 549                 sverrno = errno;
 550                 if (sysctlbyname("kern.ipc.shmmin", &lvalue, &len, NULL,
 551                     0) == -1) {
 552                         errno = sverrno;
 553                         return (-1);
 554                 }
 555                 errno = sverrno;
 556                 return (1);
 557         case _SC_XOPEN_STREAMS:
 558                 return (_XOPEN_STREAMS);
 559         case _SC_XOPEN_UNIX:
 560                 return (_XOPEN_UNIX);
 561 #ifdef _XOPEN_VERSION
 562         case _SC_XOPEN_VERSION:
 563                 return (_XOPEN_VERSION);
 564 #endif
 565 #ifdef _XOPEN_XCU_VERSION
 566         case _SC_XOPEN_XCU_VERSION:
 567                 return (_XOPEN_XCU_VERSION);
 568 #endif
 569         case _SC_SYMLOOP_MAX:
 570                 return (MAXSYMLINKS);
 571         case _SC_RAW_SOCKETS:
 572                 return (_POSIX_RAW_SOCKETS);
 573         case _SC_IPV6:
 574 #if _POSIX_IPV6 == 0
 575                 sverrno = errno;
 576                 value = socket(PF_INET6, SOCK_DGRAM, 0);
 577                 errno = sverrno;
 578                 if (value >= 0) {
 579                         close(value);
 580                         return (200112L);
 581                 } else
 582                         return (0);
 583 #else
 584                 return (_POSIX_IPV6);
 585 #endif
 586
 587         case _SC_NPROCESSORS_CONF:
 588         case _SC_NPROCESSORS_ONLN:
 589                 mib[0] = CTL_HW;
 590                 mib[1] = HW_NCPU;
 591                 break;
 592
 593 #ifdef _SC_PHYS_PAGES
 594         case _SC_PHYS_PAGES:
 595                 len = sizeof(lvalue);
 596                 if (sysctlbyname("hw.availpages", &lvalue, &len, NULL, 0) == -1)
 597                         return (-1);
 598                 return (lvalue);
 599 #endif
 600
 601         default:
 602                 errno = EINVAL;
 603                 return (-1);
 604         }
 605         len = sizeof(value);
 606         if (sysctl(mib, 2, &value, &len, NULL, 0) == -1)
 607                 value = -1;
 608         return ((long)value);
 609 }