src/runtime/bsd-os.c

   1 /*
   2  * OS-dependent routines for BSD-ish systems
   3  *
   4  * This file (along with os.h) exports an OS-independent interface to
   5  * the operating system VM facilities. This interface looks a lot like
   6  * the Mach interface (but simpler in some places). For some operating
   7  * systems, a subset of these functions will have to be emulated.
   8  */
   9
  10 /*
  11  * This software is part of the SBCL system. See the README file for
  12  * more information.
  13  *
  14  * This software is derived from the CMU CL system, which was
  15  * written at Carnegie Mellon University and released into the
  16  * public domain. The software is in the public domain and is
  17  * provided with absolutely no warranty. See the COPYING and CREDITS
  18  * files for more information.
  19  */
  20
  21 #include <stdio.h>
  22 #include <sys/param.h>
  23 #include <sys/file.h>
  24 #include <unistd.h>
  25 #include <utime.h>
  26 #include <assert.h>
  27 #include <errno.h>
  28 #include "sbcl.h"
  29 #include "./signal.h"
  30 #include "os.h"
  31 #include "arch.h"
  32 #include "globals.h"
  33 #include "interrupt.h"
  34 #include "interr.h"
  35 #include "lispregs.h"
  36 #include "thread.h"
  37 #include "runtime.h"
  38 #include "genesis/static-symbols.h"
  39 #include "genesis/fdefn.h"
  40
  41 #include <sys/types.h>
  42 #include <signal.h>
  43 /* #include <sys/sysinfo.h> */
  44 #include "validate.h"
  45 #if defined LISP_FEATURE_GENCGC
  46 #include "gencgc-internal.h"
  47 #endif
  48
  49 #if defined(LISP_FEATURE_SB_WTIMER) && !defined(LISP_FEATURE_DARWIN)
  50 # include <sys/event.h>
  51 #endif
  52
  53 \f
  54 os_vm_size_t os_vm_page_size;
  55
  56 #ifdef __NetBSD__
  57 #include <sys/resource.h>
  58 #include <sys/sysctl.h>
  59 #include <string.h>
  60 #include <sys/stat.h> /* For the stat-family wrappers. */
  61 #include <dirent.h>   /* For the opendir()/readdir() wrappers */
  62 #include <sys/socket.h> /* For the socket() wrapper */
  63 static void netbsd_init();
  64 static os_vm_size_t max_allocation_size;
  65 #endif /* __NetBSD__ */
  66
  67 #if defined LISP_FEATURE_FREEBSD
  68 #include <sys/sysctl.h>
  69 #if defined(LISP_FEATURE_SB_THREAD) && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
  70 #include <sys/umtx.h>
  71 #endif
  72
  73 static void freebsd_init();
  74 #endif /* __FreeBSD__ */
  75
  76 #ifdef __DragonFly__
  77 #include <sys/sysctl.h>
  78
  79 static void dragonfly_init();
  80 #endif /* __DragonFly__ */
  81
  82 #ifdef __OpenBSD__
  83 #include <sys/types.h>
  84 #include <sys/resource.h>
  85 #include <sys/stat.h>
  86 #include <sys/sysctl.h>
  87 #include <dlfcn.h>
  88 #ifdef LISP_FEATURE_X86
  89 #include <machine/cpu.h>
  90 #endif
  91
  92 static void openbsd_init();
  93 #endif
  94
  95 void
  96 os_init(char *argv[], char *envp[])
  97 {
  98     os_vm_page_size = BACKEND_PAGE_BYTES;
  99
 100 #ifdef __NetBSD__
 101     netbsd_init();
 102 #elif defined(LISP_FEATURE_FREEBSD)
 103     freebsd_init();
 104 #elif defined(__OpenBSD__)
 105     openbsd_init();
 106 #elif defined(LISP_FEATURE_DARWIN)
 107     darwin_init();
 108 #elif defined(__DragonFly__)
 109     dragonfly_init();
 110 #endif
 111 }
 112
 113 sigset_t *
 114 os_context_sigmask_addr(os_context_t *context)
 115 {
 116     /* (Unlike most of the other context fields that we access, the
 117      * signal mask field is a field of the basic, outermost context
 118      * struct itself both in FreeBSD 4.0 and in OpenBSD 2.6.) */
 119 #if defined(LISP_FEATURE_FREEBSD) || defined(__NetBSD__) || defined(LISP_FEATURE_DARWIN) \
 120     || defined(__DragonFly__)
 121     return &context->uc_sigmask;
 122 #elif defined (__OpenBSD__)
 123     return &context->sc_mask;
 124 #else
 125 #error unsupported BSD variant
 126 #endif
 127 }
 128
 129 os_vm_address_t
 130 os_validate(os_vm_address_t addr, os_vm_size_t len)
 131 {
 132     int flags = MAP_PRIVATE | MAP_ANON;
 133
 134     if (addr)
 135         flags |= MAP_FIXED;
 136
 137 #ifdef __NetBSD__
 138     if (addr) {
 139         os_vm_address_t curaddr = addr;
 140
 141         while (len > 0) {
 142             os_vm_address_t resaddr;
 143             os_vm_size_t curlen = MIN(max_allocation_size, len);
 144
 145             resaddr = mmap(curaddr, curlen, OS_VM_PROT_ALL, flags, -1, 0);
 146
 147             if (resaddr == (os_vm_address_t) - 1) {
 148                 perror("mmap");
 149
 150                 while (curaddr > addr) {
 151                     curaddr -= max_allocation_size;
 152                     munmap(curaddr, max_allocation_size);
 153                 }
 154
 155                 return NULL;
 156             }
 157
 158             curaddr += curlen;
 159             len -= curlen;
 160         }
 161     } else
 162 #endif
 163     {
 164         addr = mmap(addr, len, OS_VM_PROT_ALL, flags, -1, 0);
 165     }
 166
 167     if (addr == MAP_FAILED) {
 168         perror("mmap");
 169         return NULL;
 170     }
 171
 172     return addr;
 173 }
 174
 175 void
 176 os_invalidate(os_vm_address_t addr, os_vm_size_t len)
 177 {
 178     if (munmap(addr, len) == -1)
 179         perror("munmap");
 180 }
 181
 182 os_vm_address_t
 183 os_map(int fd, int offset, os_vm_address_t addr, os_vm_size_t len)
 184 {
 185     addr = mmap(addr, len,
 186                 OS_VM_PROT_ALL,
 187                 MAP_PRIVATE | MAP_FILE | MAP_FIXED,
 188                 fd, (off_t) offset);
 189
 190     if (addr == MAP_FAILED) {
 191         perror("mmap");
 192         lose("unexpected mmap(..) failure\n");
 193     }
 194
 195     return addr;
 196 }
 197
 198 void
 199 os_protect(os_vm_address_t address, os_vm_size_t length, os_vm_prot_t prot)
 200 {
 201     if (mprotect(address, length, prot) == -1) {
 202         perror("mprotect");
 203     }
 204 }
 205 \f
 206 static boolean
 207 in_range_p(os_vm_address_t a, lispobj sbeg, size_t slen)
 208 {
 209     char* beg = (char*) sbeg;
 210     char* end = (char*) sbeg + slen;
 211     char* adr = (char*) a;
 212     return (adr >= beg && adr < end);
 213 }
 214
 215 boolean
 216 is_valid_lisp_addr(os_vm_address_t addr)
 217 {
 218     struct thread *th;
 219
 220     if (in_range_p(addr, READ_ONLY_SPACE_START, READ_ONLY_SPACE_SIZE) ||
 221         in_range_p(addr, STATIC_SPACE_START, STATIC_SPACE_SIZE) ||
 222         in_range_p(addr, DYNAMIC_SPACE_START, dynamic_space_size))
 223         return 1;
 224     for_each_thread(th) {
 225         if (((os_vm_address_t)th->control_stack_start <= addr) &&
 226             (addr < (os_vm_address_t)th->control_stack_end))
 227             return 1;
 228         if (in_range_p(addr, (lispobj) th->binding_stack_start,
 229                        BINDING_STACK_SIZE))
 230             return 1;
 231     }
 232     return 0;
 233 }
 234 \f
 235 /*
 236  * any OS-dependent special low-level handling for signals
 237  */
 238
 239 #if defined LISP_FEATURE_GENCGC
 240
 241 /*
 242  * The GENCGC needs to be hooked into whatever signal is raised for
 243  * page fault on this OS.
 244  */
 245
 246 void
 247 memory_fault_handler(int signal, siginfo_t *siginfo, os_context_t *context)
 248 {
 249     void *fault_addr = arch_get_bad_addr(signal, siginfo, context);
 250
 251 #if defined(LISP_FEATURE_RESTORE_TLS_SEGMENT_REGISTER_FROM_CONTEXT)
 252     FSHOW_SIGNAL((stderr, "/ TLS: restoring fs: %p in memory_fault_handler\n",
 253                   *CONTEXT_ADDR_FROM_STEM(fs)));
 254     os_restore_tls_segment_register(context);
 255 #endif
 256
 257     FSHOW((stderr, "Memory fault at: %p, PC: %p\n", fault_addr, *os_context_pc_addr(context)));
 258
 259 #ifdef LISP_FEATURE_SB_SAFEPOINT
 260     if (!handle_safepoint_violation(context, fault_addr))
 261 #endif
 262
 263     if (!gencgc_handle_wp_violation(fault_addr))
 264         if(!handle_guard_page_triggered(context,fault_addr))
 265             lisp_memory_fault_error(context, fault_addr);
 266 }
 267
 268 #if defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 269 void
 270 mach_error_memory_fault_handler(int signal, siginfo_t *siginfo,
 271                                 os_context_t *context) {
 272     lose("Unhandled memory fault. Exiting.");
 273 }
 274 #endif
 275
 276 void
 277 os_install_interrupt_handlers(void)
 278 {
 279     SHOW("os_install_interrupt_handlers()/bsd-os/defined(GENCGC)");
 280 #if defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 281     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 282                                                  mach_error_memory_fault_handler);
 283 #else
 284     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 285 #if defined(LISP_FEATURE_FREEBSD) && !defined(__GLIBC__)
 286                                                  (__siginfohandler_t *)
 287 #endif
 288                                                  memory_fault_handler);
 289 #endif
 290
 291 #ifdef LISP_FEATURE_SB_THREAD
 292 # ifdef LISP_FEATURE_SB_SAFEPOINT
 293 #  ifdef LISP_FEATURE_SB_THRUPTION
 294     undoably_install_low_level_interrupt_handler(SIGPIPE, thruption_handler);
 295 #  endif
 296 # else
 297     undoably_install_low_level_interrupt_handler(SIG_STOP_FOR_GC,
 298                                                  sig_stop_for_gc_handler);
 299 # endif
 300 #endif
 301     SHOW("leaving os_install_interrupt_handlers()");
 302 }
 303
 304 #else /* Currently PPC/Darwin/Cheney only */
 305
 306 static void
 307 sigsegv_handler(int signal, siginfo_t *info, os_context_t *context)
 308 {
 309 #if 0
 310     unsigned int pc =  (unsigned int *)(*os_context_pc_addr(context));
 311 #endif
 312     os_vm_address_t addr;
 313
 314     addr = arch_get_bad_addr(signal, info, context);
 315     if (!cheneygc_handle_wp_violation(context, addr))
 316         if (!handle_guard_page_triggered(context, addr))
 317             interrupt_handle_now(signal, info, context);
 318 }
 319
 320 void
 321 os_install_interrupt_handlers(void)
 322 {
 323     SHOW("os_install_interrupt_handlers()/bsd-os/!defined(GENCGC)");
 324     undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
 325                                                  sigsegv_handler);
 326 }
 327
 328 #endif /* defined GENCGC */
 329
 330 #ifdef __NetBSD__
 331 static void netbsd_init()
 332 {
 333     struct rlimit rl;
 334     int mib[2], osrev;
 335     size_t len;
 336
 337     /* Are we running on a sufficiently functional kernel? */
 338     mib[0] = CTL_KERN;
 339     mib[1] = KERN_OSREV;
 340
 341     len = sizeof(osrev);
 342     sysctl(mib, 2, &osrev, &len, NULL, 0);
 343
 344     /* If we're older than 2.0... */
 345     if (osrev < 200000000) {
 346         fprintf(stderr, "osrev = %d (needed at least 200000000).\n", osrev);
 347         lose("NetBSD kernel too old to run sbcl.\n");
 348     }
 349
 350     /* NetBSD counts mmap()ed space against the process's data size limit,
 351      * so yank it up. This might be a nasty thing to do? */
 352     getrlimit (RLIMIT_DATA, &rl);
 353     if (rl.rlim_cur < rl.rlim_max) {
 354         rl.rlim_cur = rl.rlim_max;
 355         if (setrlimit (RLIMIT_DATA, &rl) < 0) {
 356             fprintf (stderr,
 357                      "RUNTIME WARNING: unable to raise process data size limit:\n\
 358 %s.\n\
 359 The system may fail to start.\n",
 360                      strerror(errno));
 361         }
 362     }
 363     max_allocation_size = (os_vm_size_t)((rl.rlim_cur / 2) &
 364       ~(32 * 1024 * 1024));
 365
 366 #ifdef LISP_FEATURE_X86
 367     {
 368         size_t len;
 369         int sse;
 370
 371         len = sizeof(sse);
 372         if (sysctlbyname("machdep.sse", &sse, &len,
 373                          NULL, 0) == 0 && sse != 0) {
 374             /* Use the SSE detector */
 375             fast_bzero_pointer = fast_bzero_detect;
 376         }
 377      }
 378 #endif /* LISP_FEATURE_X86 */
 379 }
 380
 381 /* Various routines in NetBSD's C library are compatibility wrappers
 382    for old versions. Programs must be processed by the C toolchain in
 383    order to get up-to-date definitions of such routines. */
 384 /* The stat-family, opendir, and readdir are used only in sb-posix, as
 385    of 2007-01-16. -- RMK */
 386 int
 387 _stat(const char *path, struct stat *sb)
 388 {
 389     return stat(path, sb);
 390 }
 391 int
 392 _lstat(const char *path, struct stat *sb)
 393 {
 394     return lstat(path, sb);
 395 }
 396 int
 397 _fstat(int fd, struct stat *sb)
 398 {
 399     return fstat(fd, sb);
 400 }
 401
 402 DIR *
 403 _opendir(const char *filename)
 404 {
 405     return opendir(filename);
 406 }
 407 struct dirent *
 408 _readdir(DIR *dirp)
 409 {
 410     return readdir(dirp);
 411 }
 412
 413 int
 414 _utime(const char *file, const struct utimbuf *timep)
 415 {
 416     return utime(file, timep);
 417 }
 418
 419 /* Used in sb-bsd-sockets. */
 420 int
 421 _socket(int domain, int type, int protocol)
 422 {
 423     return socket(domain, type, protocol);
 424 }
 425 #endif /* __NetBSD__ */
 426
 427 #if defined(LISP_FEATURE_FREEBSD)
 428 #ifndef __GLIBC__
 429 extern int getosreldate(void);
 430 #endif
 431
 432 int sig_memory_fault;
 433
 434 static void freebsd_init()
 435 {
 436     /* Memory fault signal on FreeBSD was changed from SIGBUS to
 437      * SIGSEGV. */
 438 #ifdef __GLIBC__
 439         sig_memory_fault = SIGSEGV;
 440 #else
 441     if (getosreldate() < 700004)
 442         sig_memory_fault = SIGBUS;
 443     else
 444         sig_memory_fault = SIGSEGV;
 445 #endif
 446
 447     /* Quote from sbcl-devel (NIIMI Satoshi): "Some OSes, like FreeBSD
 448      * 4.x with GENERIC kernel, does not enable SSE support even on
 449      * SSE capable CPUs". Detect this situation and skip the
 450      * fast_bzero sse/base selection logic that's normally done in
 451      * x86-assem.S.
 452      */
 453 #ifdef LISP_FEATURE_X86
 454     {
 455         size_t len;
 456         int instruction_sse;
 457
 458         len = sizeof(instruction_sse);
 459         if (sysctlbyname("hw.instruction_sse", &instruction_sse, &len,
 460                          NULL, 0) == 0 && instruction_sse != 0) {
 461             /* Use the SSE detector */
 462             fast_bzero_pointer = fast_bzero_detect;
 463         }
 464     }
 465 #endif /* LISP_FEATURE_X86 */
 466 }
 467
 468 #if defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_SB_FUTEX) \
 469     && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
 470 int
 471 futex_wait(int *lock_word, long oldval, long sec, unsigned long usec)
 472 {
 473     struct timespec timeout;
 474     int ret;
 475
 476     if (sec < 0)
 477         ret = umtx_wait((void *)lock_word, oldval, NULL);
 478     else {
 479         timeout.tv_sec = sec;
 480         timeout.tv_nsec = usec * 1000;
 481         ret = umtx_wait((void *)lock_word, oldval, &timeout);
 482     }
 483
 484     switch (ret) {
 485     case 0:
 486         return 0;
 487     case ETIMEDOUT:
 488         return 1;
 489     case EINTR:
 490         return 2;
 491     default:
 492         /* EWOULDBLOCK and others, need to check the lock */
 493         return -1;
 494     }
 495 }
 496
 497 int
 498 futex_wake(int *lock_word, int n)
 499 {
 500     return umtx_wake((void *)lock_word, n);
 501 }
 502 #endif
 503 #endif /* __FreeBSD__ */
 504
 505 #ifdef __DragonFly__
 506 static void dragonfly_init()
 507 {
 508 #ifdef LISP_FEATURE_X86
 509     size_t len;
 510     int instruction_sse;
 511
 512     len = sizeof(instruction_sse);
 513     if (sysctlbyname("hw.instruction_sse", &instruction_sse, &len,
 514                      NULL, 0) == 0 && instruction_sse != 0) {
 515         /* Use the SSE detector */
 516         fast_bzero_pointer = fast_bzero_detect;
 517     }
 518 #endif /* LISP_FEATURE_X86 */
 519 }
 520
 521
 522 #if defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_SB_FUTEX) \
 523     && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
 524 int
 525 futex_wait(int *lock_word, long oldval, long sec, unsigned long usec)
 526 {
 527     int ret;
 528
 529     if (sec < 0)
 530         ret = umtx_sleep(lock_word, oldval, 0);
 531     else {
 532         int count = usec + 1000000 * sec;
 533         ret = umtx_sleep(lock_word, oldval, count);
 534     }
 535
 536     if (ret == 0) return 0;
 537     else {
 538         switch (errno) {
 539         case EWOULDBLOCK: // Operation timed out
 540             return 1;
 541         case EINTR:
 542             return 2;
 543         default: // Such as EINVAL or EBUSY
 544             return -1;
 545         }
 546     }
 547 }
 548
 549 int
 550 futex_wake(int *lock_word, int n)
 551 {
 552     return umtx_wakeup(lock_word, n);
 553 }
 554 #endif
 555 #endif /* __DragonFly__ */
 556
 557 #ifdef LISP_FEATURE_DARWIN
 558 /* defined in ppc-darwin-os.c instead */
 559 #elif defined(LISP_FEATURE_FREEBSD)
 560 #ifndef KERN_PROC_PATHNAME
 561 #define KERN_PROC_PATHNAME 12
 562 #endif
 563
 564 char *
 565 os_get_runtime_executable_path(int external)
 566 {
 567     char path[PATH_MAX + 1];
 568
 569 #ifndef __GLIBC__
 570     if (getosreldate() >= 600024) {
 571 #endif
 572         /* KERN_PROC_PATHNAME is available */
 573         size_t len = PATH_MAX + 1;
 574         int mib[4];
 575
 576         mib[0] = CTL_KERN;
 577         mib[1] = KERN_PROC;
 578         mib[2] = KERN_PROC_PATHNAME;
 579         mib[3] = -1;
 580         if (sysctl(mib, 4, &path, &len, NULL, 0) != 0)
 581             return NULL;
 582 #ifndef __GLIBC__
 583     } else {
 584         int size;
 585         size = readlink("/proc/curproc/file", path, sizeof(path) - 1);
 586         if (size < 0)
 587             return NULL;
 588         path[size] = '\0';
 589     }
 590 #endif
 591     if (strcmp(path, "unknown") == 0)
 592         return NULL;
 593     return copied_string(path);
 594 }
 595 #elif defined(LISP_FEATURE_DRAGONFLY)
 596 char *
 597 os_get_runtime_executable_path(int external)
 598 {
 599     char path[PATH_MAX + 1];
 600     int size = readlink("/proc/curproc/file", path, sizeof(path) - 1);
 601     if (size < 0)
 602         return NULL;
 603     path[size] = '\0';
 604
 605     if (strcmp(path, "unknown") == 0)
 606         return NULL;
 607     return copied_string(path);
 608 }
 609 #elif defined(LISP_FEATURE_NETBSD) || defined(LISP_FEATURE_OPENBSD)
 610 char *
 611 os_get_runtime_executable_path(int external)
 612 {
 613     struct stat sb;
 614     if (!external && stat("/proc/curproc/file", &sb) == 0)
 615         return copied_string("/proc/curproc/file");
 616     return NULL;
 617 }
 618 #else /* Not DARWIN or FREEBSD or NETBSD or OPENBSD or DragonFly */
 619 char *
 620 os_get_runtime_executable_path(int external)
 621 {
 622     return NULL;
 623 }
 624 #endif
 625
 626 #ifdef __OpenBSD__
 627
 628 int openbsd_use_fxsave = 0;
 629
 630 void
 631 openbsd_init()
 632 {
 633 #ifdef LISP_FEATURE_X86
 634     int mib[2];
 635     size_t size;
 636 #endif
 637     /*
 638      * Show a warning if it looks like the memory available after
 639      * allocating the spaces won't be at least this much.
 640      */
 641 #ifdef LISP_FEATURE_X86_64
 642     const int wantfree = 64 * 1024 * 1024;
 643 #else
 644     const int wantfree = 32 * 1024 * 1024;
 645 #endif
 646     struct rlimit rl;
 647
 648 #ifdef LISP_FEATURE_X86
 649     /* Save the machdep.osfxsr sysctl for use by os_restore_fp_control() */
 650     mib[0] = CTL_MACHDEP;
 651     mib[1] = CPU_OSFXSR;
 652     size = sizeof (openbsd_use_fxsave);
 653     sysctl(mib, 2, &openbsd_use_fxsave, &size, NULL, 0);
 654 #endif
 655
 656     /* OpenBSD, like NetBSD, counts mmap()ed space against the
 657      * process's data size limit. If the soft limit is lower than the
 658      * hard limit then try to yank it up, this lets users in the
 659      * "staff" or "daemon" login classes run sbcl with larger dynamic
 660      * space sizes.
 661      */
 662     getrlimit (RLIMIT_DATA, &rl);
 663     if (rl.rlim_cur < rl.rlim_max) {
 664         rl.rlim_cur = rl.rlim_max;
 665         if (setrlimit (RLIMIT_DATA, &rl) < 0) {
 666             fprintf (stderr,
 667                      "RUNTIME WARNING: unable to raise process data size limit:\n\
 668   %s.\n\
 669 The system may fail to start.\n",
 670                      strerror(errno));
 671         }
 672     }
 673
 674     /*
 675      * Display a (hopefully) helpful warning if it looks like we won't
 676      * be able to allocate enough memory.
 677      */
 678     getrlimit (RLIMIT_DATA, &rl);
 679     if (dynamic_space_size + READ_ONLY_SPACE_SIZE + STATIC_SPACE_SIZE +
 680         LINKAGE_TABLE_SPACE_SIZE + wantfree > rl.rlim_cur)
 681         fprintf (stderr,
 682                  "RUNTIME WARNING: data size resource limit may be too low,\n"
 683                  "  try decreasing the dynamic space size with --dynamic-space-size\n"
 684                  "  or raising the datasize or datasize-max limits in /etc/login.conf\n");
 685 }
 686
 687 /* OpenBSD's dlsym() relies on the gcc bulitin
 688  * __builtin_return_address(0) returning an address in the
 689  * executable's text segment, but when called from lisp it will return
 690  * an address in the dynamic space.  Work around this by calling this
 691  * wrapper function instead. Note that tail-call optimization will
 692  * defeat this, disable it by saving the dlsym() return value in a
 693  * volatile variable.
 694 */
 695 void *
 696 os_dlsym(void *handle, const char *symbol)
 697 {
 698     void * volatile ret = dlsym(handle, symbol);
 699     return ret;
 700 }
 701
 702 #endif
 703
 704 #if defined(LISP_FEATURE_SB_WTIMER) && !defined(LISP_FEATURE_DARWIN)
 705 /*
 706  * Waitable timer implementation for the safepoint-based (SIGALRM-free)
 707  * timer facility using kqueue.
 708  */
 709 int
 710 os_create_wtimer()
 711 {
 712     int kq = kqueue();
 713     if (kq == -1)
 714         lose("os_create_wtimer: kqueue");
 715     return kq;
 716 }
 717
 718 int
 719 os_wait_for_wtimer(int kq)
 720 {
 721     struct kevent ev;
 722     int n;
 723     if ( (n = kevent(kq, 0, 0, &ev, 1, 0)) == -1) {
 724         if (errno != EINTR)
 725             lose("os_wtimer_listen failed");
 726         n = 0;
 727     }
 728     return n != 1;
 729 }
 730
 731 void
 732 os_close_wtimer(int kq)
 733 {
 734     if (close(kq) == -1)
 735         lose("os_close_wtimer failed");
 736 }
 737
 738 void
 739 os_set_wtimer(int kq, int sec, int nsec)
 740 {
 741     long long msec
 742         = ((long long) sec) * 1000 + (long long) (nsec+999999) / 1000000;
 743     if (msec > INT_MAX) msec = INT_MAX;
 744
 745     struct kevent ev;
 746     EV_SET(&ev, 1, EVFILT_TIMER, EV_ADD|EV_ENABLE|EV_ONESHOT, 0, (int)msec, 0);
 747     if (kevent(kq, &ev, 1, 0, 0, 0) == -1)
 748         perror("os_set_wtimer: kevent");
 749 }
 750
 751 void
 752 os_cancel_wtimer(int kq)
 753 {
 754     struct kevent ev;
 755     EV_SET(&ev, 1, EVFILT_TIMER, EV_DISABLE, 0, 0, 0);
 756     if (kevent(kq, &ev, 1, 0, 0, 0) == -1 && errno != ENOENT)
 757         perror("os_cancel_wtimer: kevent");
 758 }
 759 #endif