1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include "lint.h"
28 #include <sys/feature_tests.h>
29 /*
30 * setcontext() really can return, if UC_CPU is not specified.
31 * Make the compiler shut up about it.
32 */
33 #if defined(__NORETURN)
34 #undef __NORETURN
35 #endif
36 #define __NORETURN
37 #include "thr_uberdata.h"
38 #include "asyncio.h"
39 #include <signal.h>
40 #include <siginfo.h>
41 #include <sys/systm.h>
42
43 /* maskable signals */
44 const sigset_t maskset = {MASKSET0, MASKSET1, MASKSET2, MASKSET3};
45
46 /*
47 * Return true if the valid signal bits in both sets are the same.
48 */
49 int
50 sigequalset(const sigset_t *s1, const sigset_t *s2)
51 {
52 /*
53 * We only test valid signal bits, not rubbish following MAXSIG
54 * (for speed). Algorithm:
55 * if (s1 & fillset) == (s2 & fillset) then (s1 ^ s2) & fillset == 0
56 */
57 /* see lib/libc/inc/thr_uberdata.h for why this must be true */
58 #if (MAXSIG > (2 * 32) && MAXSIG <= (3 * 32))
59 return (!((s1->__sigbits[0] ^ s2->__sigbits[0]) |
60 (s1->__sigbits[1] ^ s2->__sigbits[1]) |
61 ((s1->__sigbits[2] ^ s2->__sigbits[2]) & FILLSET2)));
62 #else
63 #error "fix me: MAXSIG out of bounds"
64 #endif
65 }
66
67 /*
68 * Common code for calling the user-specified signal handler.
69 */
70 void
71 call_user_handler(int sig, siginfo_t *sip, ucontext_t *ucp)
72 {
73 ulwp_t *self = curthread;
74 uberdata_t *udp = self->ul_uberdata;
75 struct sigaction uact;
76 volatile struct sigaction *sap;
77
78 /*
79 * If we are taking a signal while parked or about to be parked
80 * on __lwp_park() then remove ourself from the sleep queue so
81 * that we can grab locks. The code in mutex_lock_queue() and
82 * cond_wait_common() will detect this and deal with it when
83 * __lwp_park() returns.
84 */
85 unsleep_self();
86 set_parking_flag(self, 0);
87
88 if (__td_event_report(self, TD_CATCHSIG, udp)) {
89 self->ul_td_evbuf.eventnum = TD_CATCHSIG;
90 self->ul_td_evbuf.eventdata = (void *)(intptr_t)sig;
91 tdb_event(TD_CATCHSIG, udp);
92 }
93
94 /*
95 * Get a self-consistent set of flags, handler, and mask
96 * while holding the sig's sig_lock for the least possible time.
97 * We must acquire the sig's sig_lock because some thread running
98 * in sigaction() might be establishing a new signal handler.
99 * The code in sigaction() acquires the writer lock; here
100 * we acquire the readers lock to ehance concurrency in the
101 * face of heavy signal traffic, such as generated by java.
102 *
103 * Locking exceptions:
104 * No locking for a child of vfork().
105 * If the signal is SIGPROF with an si_code of PROF_SIG,
106 * then we assume that this signal was generated by
107 * setitimer(ITIMER_REALPROF) set up by the dbx collector.
108 * If the signal is SIGEMT with an si_code of EMT_CPCOVF,
109 * then we assume that the signal was generated by
110 * a hardware performance counter overflow.
111 * In these cases, assume that we need no locking. It is the
112 * monitoring program's responsibility to ensure correctness.
113 */
114 sap = &udp->siguaction[sig].sig_uaction;
115 if (self->ul_vfork ||
116 (sip != NULL &&
117 ((sig == SIGPROF && sip->si_code == PROF_SIG) ||
118 (sig == SIGEMT && sip->si_code == EMT_CPCOVF)))) {
119 /* we wish this assignment could be atomic */
120 (void) memcpy(&uact, (void *)sap, sizeof (uact));
121 } else {
122 rwlock_t *rwlp = &udp->siguaction[sig].sig_lock;
123 lrw_rdlock(rwlp);
124 (void) memcpy(&uact, (void *)sap, sizeof (uact));
125 if ((sig == SIGCANCEL || sig == SIGAIOCANCEL) &&
126 (sap->sa_flags & SA_RESETHAND))
127 sap->sa_sigaction = SIG_DFL;
128 lrw_unlock(rwlp);
129 }
130
131 /*
132 * Set the proper signal mask and call the user's signal handler.
133 * (We overrode the user-requested signal mask with maskset
134 * so we currently have all blockable signals blocked.)
135 *
136 * We would like to ASSERT() that the signal is not a member of the
137 * signal mask at the previous level (ucp->uc_sigmask) or the specified
138 * signal mask for sigsuspend() or pollsys() (self->ul_tmpmask) but
139 * /proc can override this via PCSSIG, so we don't bother.
140 *
141 * We would also like to ASSERT() that the signal mask at the previous
142 * level equals self->ul_sigmask (maskset for sigsuspend() / pollsys()),
143 * but /proc can change the thread's signal mask via PCSHOLD, so we
144 * don't bother with that either.
145 */
146 ASSERT(ucp->uc_flags & UC_SIGMASK);
147 if (self->ul_sigsuspend) {
148 ucp->uc_sigmask = self->ul_sigmask;
149 self->ul_sigsuspend = 0;
150 /* the sigsuspend() or pollsys() signal mask */
151 sigorset(&uact.sa_mask, &self->ul_tmpmask);
152 } else {
153 /* the signal mask at the previous level */
154 sigorset(&uact.sa_mask, &ucp->uc_sigmask);
155 }
156 if (!(uact.sa_flags & SA_NODEFER)) /* add current signal */
157 (void) sigaddset(&uact.sa_mask, sig);
158 self->ul_sigmask = uact.sa_mask;
159 self->ul_siglink = ucp;
160 (void) __lwp_sigmask(SIG_SETMASK, &uact.sa_mask);
161
162 /*
163 * If this thread has been sent SIGCANCEL from the kernel
164 * or from pthread_cancel(), it is being asked to exit.
165 * The kernel may send SIGCANCEL without a siginfo struct.
166 * If the SIGCANCEL is process-directed (from kill() or
167 * sigqueue()), treat it as an ordinary signal.
168 */
169 if (sig == SIGCANCEL) {
170 if (sip == NULL || SI_FROMKERNEL(sip) ||
171 sip->si_code == SI_LWP) {
172 do_sigcancel();
173 goto out;
174 }
175 /* SIGCANCEL is ignored by default */
176 if (uact.sa_sigaction == SIG_DFL ||
177 uact.sa_sigaction == SIG_IGN)
178 goto out;
179 }
180
181 /*
182 * If this thread has been sent SIGAIOCANCEL (SIGLWP) and
183 * we are an aio worker thread, cancel the aio request.
184 */
185 if (sig == SIGAIOCANCEL) {
186 aio_worker_t *aiowp = pthread_getspecific(_aio_key);
187
188 if (sip != NULL && sip->si_code == SI_LWP && aiowp != NULL)
189 siglongjmp(aiowp->work_jmp_buf, 1);
190 /* SIGLWP is ignored by default */
191 if (uact.sa_sigaction == SIG_DFL ||
192 uact.sa_sigaction == SIG_IGN)
193 goto out;
194 }
195
196 if (!(uact.sa_flags & SA_SIGINFO))
197 sip = NULL;
198 __sighndlr(sig, sip, ucp, uact.sa_sigaction);
199
200 #if defined(sparc) || defined(__sparc)
201 /*
202 * If this is a floating point exception and the queue
203 * is non-empty, pop the top entry from the queue. This
204 * is to maintain expected behavior.
205 */
206 if (sig == SIGFPE && ucp->uc_mcontext.fpregs.fpu_qcnt) {
207 fpregset_t *fp = &ucp->uc_mcontext.fpregs;
208
209 if (--fp->fpu_qcnt > 0) {
210 unsigned char i;
211 struct fq *fqp;
212
213 fqp = fp->fpu_q;
214 for (i = 0; i < fp->fpu_qcnt; i++)
215 fqp[i] = fqp[i+1];
216 }
217 }
218 #endif /* sparc */
219
220 out:
221 (void) setcontext(ucp);
222 thr_panic("call_user_handler(): setcontext() returned");
223 }
224
225 /*
226 * take_deferred_signal() is called when ul_critical and ul_sigdefer become
227 * zero and a deferred signal has been recorded on the current thread.
228 * We are out of the critical region and are ready to take a signal.
229 * The kernel has all signals blocked on this lwp, but our value of
230 * ul_sigmask is the correct signal mask for the previous context.
231 *
232 * We call __sigresend() to atomically restore the signal mask and
233 * cause the signal to be sent again with the remembered siginfo.
234 * We will not return successfully from __sigresend() until the
235 * application's signal handler has been run via sigacthandler().
236 */
237 void
238 take_deferred_signal(int sig)
239 {
240 extern int __sigresend(int, siginfo_t *, sigset_t *);
241 ulwp_t *self = curthread;
242 siguaction_t *suap = &self->ul_uberdata->siguaction[sig];
243 siginfo_t *sip;
244 int error;
245
246 ASSERT((self->ul_critical | self->ul_sigdefer | self->ul_cursig) == 0);
247
248 /*
249 * If the signal handler was established with SA_RESETHAND,
250 * the kernel has reset the handler to SIG_DFL, so we have
251 * to reestablish the handler now so that it will be entered
252 * again when we call __sigresend(), below.
253 *
254 * Logically, we should acquire and release the signal's
255 * sig_lock around this operation to protect the integrity
256 * of the signal action while we copy it, as is done below
257 * in _libc_sigaction(). However, we may be on a user-level
258 * sleep queue at this point and lrw_wrlock(&suap->sig_lock)
259 * might attempt to sleep on a different sleep queue and
260 * that would corrupt the entire sleep queue mechanism.
261 *
262 * If we are on a sleep queue we will remove ourself from
263 * it in call_user_handler(), called from sigacthandler(),
264 * before entering the application's signal handler.
265 * In the meantime, we must not acquire any locks.
266 */
267 if (suap->sig_uaction.sa_flags & SA_RESETHAND) {
268 struct sigaction tact = suap->sig_uaction;
269 tact.sa_flags &= ~SA_NODEFER;
270 tact.sa_sigaction = self->ul_uberdata->sigacthandler;
271 tact.sa_mask = maskset;
272 (void) __sigaction(sig, &tact, NULL);
273 }
274
275 if (self->ul_siginfo.si_signo == 0)
276 sip = NULL;
277 else
278 sip = &self->ul_siginfo;
279
280 /* EAGAIN can happen only for a pending SIGSTOP signal */
281 while ((error = __sigresend(sig, sip, &self->ul_sigmask)) == EAGAIN)
282 continue;
283 if (error)
284 thr_panic("take_deferred_signal(): __sigresend() failed");
285 }
286
287 void
288 sigacthandler(int sig, siginfo_t *sip, void *uvp)
289 {
290 ucontext_t *ucp = uvp;
291 ulwp_t *self = curthread;
292
293 /*
294 * Do this in case we took a signal while in a cancelable system call.
295 * It does no harm if we were not in such a system call.
296 */
297 self->ul_sp = 0;
298 if (sig != SIGCANCEL)
299 self->ul_cancel_async = self->ul_save_async;
300
301 /*
302 * If this thread has performed a longjmp() from a signal handler
303 * back to main level some time in the past, it has left the kernel
304 * thinking that it is still in the signal context. We repair this
305 * possible damage by setting ucp->uc_link to NULL if we know that
306 * we are actually executing at main level (self->ul_siglink == NULL).
307 * See the code for setjmp()/longjmp() for more details.
308 */
309 if (self->ul_siglink == NULL)
310 ucp->uc_link = NULL;
311
312 /*
313 * If we are not in a critical region and are
314 * not deferring signals, take the signal now.
315 */
316 if ((self->ul_critical + self->ul_sigdefer) == 0) {
317 call_user_handler(sig, sip, ucp);
318 /*
319 * On the surface, the following call seems redundant
320 * because call_user_handler() cannot return. However,
321 * we don't want to return from here because the compiler
322 * might recycle our frame. We want to keep it on the
323 * stack to assist debuggers such as pstack in identifying
324 * signal frames. The call to thr_panic() serves to prevent
325 * tail-call optimisation here.
326 */
327 thr_panic("sigacthandler(): call_user_handler() returned");
328 }
329
330 /*
331 * We are in a critical region or we are deferring signals. When
332 * we emerge from the region we will call take_deferred_signal().
333 */
334 ASSERT(self->ul_cursig == 0);
335 self->ul_cursig = (char)sig;
336 if (sip != NULL)
337 (void) memcpy(&self->ul_siginfo,
338 sip, sizeof (siginfo_t));
339 else
340 self->ul_siginfo.si_signo = 0;
341
342 /*
343 * Make sure that if we return to a call to __lwp_park()
344 * or ___lwp_cond_wait() that it returns right away
345 * (giving us a spurious wakeup but not a deadlock).
346 */
347 set_parking_flag(self, 0);
348
349 /*
350 * Return to the previous context with all signals blocked.
351 * We will restore the signal mask in take_deferred_signal().
352 * Note that we are calling the system call trap here, not
353 * the setcontext() wrapper. We don't want to change the
354 * thread's ul_sigmask by this operation.
355 */
356 ucp->uc_sigmask = maskset;
357 (void) __setcontext(ucp);
358 thr_panic("sigacthandler(): __setcontext() returned");
359 }
360
361 #pragma weak _sigaction = sigaction
362 int
363 sigaction(int sig, const struct sigaction *nact, struct sigaction *oact)
364 {
365 ulwp_t *self = curthread;
366 uberdata_t *udp = self->ul_uberdata;
367 struct sigaction oaction;
368 struct sigaction tact;
369 struct sigaction *tactp = NULL;
370 int rv;
371
372 if (sig <= 0 || sig >= NSIG) {
373 errno = EINVAL;
374 return (-1);
375 }
376
377 if (!self->ul_vfork)
378 lrw_wrlock(&udp->siguaction[sig].sig_lock);
379
380 oaction = udp->siguaction[sig].sig_uaction;
381
382 if (nact != NULL) {
383 tact = *nact; /* make a copy so we can modify it */
384 tactp = &tact;
385 delete_reserved_signals(&tact.sa_mask);
386
387 #if !defined(_LP64)
388 tact.sa_resv[0] = tact.sa_resv[1] = 0; /* cleanliness */
389 #endif
390 /*
391 * To be compatible with the behavior of SunOS 4.x:
392 * If the new signal handler is SIG_IGN or SIG_DFL, do
393 * not change the signal's entry in the siguaction array.
394 * This allows a child of vfork(2) to set signal handlers
395 * to SIG_IGN or SIG_DFL without affecting the parent.
396 *
397 * This also covers a race condition with some thread
398 * setting the signal action to SIG_DFL or SIG_IGN
399 * when the thread has also received and deferred
400 * that signal. When the thread takes the deferred
401 * signal, even though it has set the action to SIG_DFL
402 * or SIG_IGN, it will execute the old signal handler
403 * anyway. This is an inherent signaling race condition
404 * and is not a bug.
405 *
406 * A child of vfork() is not allowed to change signal
407 * handlers to anything other than SIG_DFL or SIG_IGN.
408 */
409 if (self->ul_vfork) {
410 if (tact.sa_sigaction != SIG_IGN)
411 tact.sa_sigaction = SIG_DFL;
412 } else if (sig == SIGCANCEL || sig == SIGAIOCANCEL) {
413 /*
414 * Always catch these signals.
415 * We need SIGCANCEL for pthread_cancel() to work.
416 * We need SIGAIOCANCEL for aio_cancel() to work.
417 */
418 udp->siguaction[sig].sig_uaction = tact;
419 if (tact.sa_sigaction == SIG_DFL ||
420 tact.sa_sigaction == SIG_IGN)
421 tact.sa_flags = SA_SIGINFO;
422 else {
423 tact.sa_flags |= SA_SIGINFO;
424 tact.sa_flags &=
425 ~(SA_NODEFER | SA_RESETHAND | SA_RESTART);
426 }
427 tact.sa_sigaction = udp->sigacthandler;
428 tact.sa_mask = maskset;
429 } else if (tact.sa_sigaction != SIG_DFL &&
430 tact.sa_sigaction != SIG_IGN) {
431 udp->siguaction[sig].sig_uaction = tact;
432 tact.sa_flags &= ~SA_NODEFER;
433 tact.sa_sigaction = udp->sigacthandler;
434 tact.sa_mask = maskset;
435 }
436 }
437
438 if ((rv = __sigaction(sig, tactp, oact)) != 0)
439 udp->siguaction[sig].sig_uaction = oaction;
440 else if (oact != NULL &&
441 oact->sa_sigaction != SIG_DFL &&
442 oact->sa_sigaction != SIG_IGN)
443 *oact = oaction;
444
445 /*
446 * We detect setting the disposition of SIGIO just to set the
447 * _sigio_enabled flag for the asynchronous i/o (aio) code.
448 */
449 if (sig == SIGIO && rv == 0 && tactp != NULL) {
450 _sigio_enabled =
451 (tactp->sa_handler != SIG_DFL &&
452 tactp->sa_handler != SIG_IGN);
453 }
454
455 if (!self->ul_vfork)
456 lrw_unlock(&udp->siguaction[sig].sig_lock);
457 return (rv);
458 }
459
460 /*
461 * This is a private interface for the linux brand interface.
462 */
463 void
464 setsigacthandler(void (*nsigacthandler)(int, siginfo_t *, void *),
465 void (**osigacthandler)(int, siginfo_t *, void *))
466 {
467 ulwp_t *self = curthread;
468 uberdata_t *udp = self->ul_uberdata;
469
470 if (osigacthandler != NULL)
471 *osigacthandler = udp->sigacthandler;
472
473 udp->sigacthandler = nsigacthandler;
474 }
475
476 /*
477 * Tell the kernel to block all signals.
478 * Use the schedctl interface, or failing that, use __lwp_sigmask().
479 * This action can be rescinded only by making a system call that
480 * sets the signal mask:
481 * __lwp_sigmask(), __sigprocmask(), __setcontext(),
482 * __sigsuspend() or __pollsys().
483 * In particular, this action cannot be reversed by assigning
484 * scp->sc_sigblock = 0. That would be a way to lose signals.
485 * See the definition of restore_signals(self).
486 */
487 void
488 block_all_signals(ulwp_t *self)
489 {
490 volatile sc_shared_t *scp;
491
492 enter_critical(self);
493 if ((scp = self->ul_schedctl) != NULL ||
494 (scp = setup_schedctl()) != NULL)
495 scp->sc_sigblock = 1;
496 else
497 (void) __lwp_sigmask(SIG_SETMASK, &maskset);
498 exit_critical(self);
499 }
500
501 /*
502 * setcontext() has code that forcibly restores the curthread
503 * pointer in a context passed to the setcontext(2) syscall.
504 *
505 * Certain processes may need to disable this feature, so these routines
506 * provide the mechanism to do so.
507 *
508 * (As an example, branded 32-bit x86 processes may use %gs for their own
509 * purposes, so they need to be able to specify a %gs value to be restored
510 * on return from a signal handler via the passed ucontext_t.)
511 */
512 static int setcontext_enforcement = 1;
513
514 void
515 set_setcontext_enforcement(int on)
516 {
517 setcontext_enforcement = on;
518 }
519
520 #pragma weak _setcontext = setcontext
521 int
522 setcontext(const ucontext_t *ucp)
523 {
524 ulwp_t *self = curthread;
525 int ret;
526 ucontext_t uc;
527
528 /*
529 * Returning from the main context (uc_link == NULL) causes
530 * the thread to exit. See setcontext(2) and makecontext(3C).
531 */
532 if (ucp == NULL)
533 thr_exit(NULL);
534 (void) memcpy(&uc, ucp, sizeof (uc));
535
536 /*
537 * Restore previous signal mask and context link.
538 */
539 if (uc.uc_flags & UC_SIGMASK) {
540 block_all_signals(self);
541 delete_reserved_signals(&uc.uc_sigmask);
542 self->ul_sigmask = uc.uc_sigmask;
543 if (self->ul_cursig) {
544 /*
545 * We have a deferred signal present.
546 * The signal mask will be set when the
547 * signal is taken in take_deferred_signal().
548 */
549 ASSERT(self->ul_critical + self->ul_sigdefer != 0);
550 uc.uc_flags &= ~UC_SIGMASK;
551 }
552 }
553 self->ul_siglink = uc.uc_link;
554
555 /*
556 * We don't know where this context structure has been.
557 * Preserve the curthread pointer, at least.
558 *
559 * Allow this feature to be disabled if a particular process
560 * requests it.
561 */
562 if (setcontext_enforcement) {
563 #if defined(__sparc)
564 uc.uc_mcontext.gregs[REG_G7] = (greg_t)self;
565 #elif defined(__amd64)
566 uc.uc_mcontext.gregs[REG_FS] = (greg_t)0; /* null for fsbase */
567 #elif defined(__i386)
568 uc.uc_mcontext.gregs[GS] = (greg_t)LWPGS_SEL;
569 #else
570 #error "none of __sparc, __amd64, __i386 defined"
571 #endif
572 }
573
574 /*
575 * Make sure that if we return to a call to __lwp_park()
576 * or ___lwp_cond_wait() that it returns right away
577 * (giving us a spurious wakeup but not a deadlock).
578 */
579 set_parking_flag(self, 0);
580 self->ul_sp = 0;
581 ret = __setcontext(&uc);
582
583 /*
584 * It is OK for setcontext() to return if the user has not specified
585 * UC_CPU.
586 */
587 if (uc.uc_flags & UC_CPU)
588 thr_panic("setcontext(): __setcontext() returned");
589 return (ret);
590 }
591
592 #pragma weak _thr_sigsetmask = thr_sigsetmask
593 int
594 thr_sigsetmask(int how, const sigset_t *set, sigset_t *oset)
595 {
596 ulwp_t *self = curthread;
597 sigset_t saveset;
598
599 if (set == NULL) {
600 enter_critical(self);
601 if (oset != NULL)
602 *oset = self->ul_sigmask;
603 exit_critical(self);
604 } else {
605 switch (how) {
606 case SIG_BLOCK:
607 case SIG_UNBLOCK:
608 case SIG_SETMASK:
609 break;
610 default:
611 return (EINVAL);
612 }
613
614 /*
615 * The assignments to self->ul_sigmask must be protected from
616 * signals. The nuances of this code are subtle. Be careful.
617 */
618 block_all_signals(self);
619 if (oset != NULL)
620 saveset = self->ul_sigmask;
621 switch (how) {
622 case SIG_BLOCK:
623 self->ul_sigmask.__sigbits[0] |= set->__sigbits[0];
624 self->ul_sigmask.__sigbits[1] |= set->__sigbits[1];
625 self->ul_sigmask.__sigbits[2] |= set->__sigbits[2];
626 self->ul_sigmask.__sigbits[3] |= set->__sigbits[3];
627 break;
628 case SIG_UNBLOCK:
629 self->ul_sigmask.__sigbits[0] &= ~set->__sigbits[0];
630 self->ul_sigmask.__sigbits[1] &= ~set->__sigbits[1];
631 self->ul_sigmask.__sigbits[2] &= ~set->__sigbits[2];
632 self->ul_sigmask.__sigbits[3] &= ~set->__sigbits[3];
633 break;
634 case SIG_SETMASK:
635 self->ul_sigmask.__sigbits[0] = set->__sigbits[0];
636 self->ul_sigmask.__sigbits[1] = set->__sigbits[1];
637 self->ul_sigmask.__sigbits[2] = set->__sigbits[2];
638 self->ul_sigmask.__sigbits[3] = set->__sigbits[3];
639 break;
640 }
641 delete_reserved_signals(&self->ul_sigmask);
642 if (oset != NULL)
643 *oset = saveset;
644 restore_signals(self);
645 }
646
647 return (0);
648 }
649
650 #pragma weak _pthread_sigmask = pthread_sigmask
651 int
652 pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
653 {
654 return (thr_sigsetmask(how, set, oset));
655 }
656
657 #pragma weak _sigprocmask = sigprocmask
658 int
659 sigprocmask(int how, const sigset_t *set, sigset_t *oset)
660 {
661 int error;
662
663 /*
664 * Guard against children of vfork().
665 */
666 if (curthread->ul_vfork)
667 return (__sigprocmask(how, set, oset));
668
669 if ((error = thr_sigsetmask(how, set, oset)) != 0) {
670 errno = error;
671 return (-1);
672 }
673
674 return (0);
675 }
676
677 /*
678 * Called at library initialization to set up signal handling.
679 * All we really do is initialize the sig_lock rwlocks.
680 * All signal handlers are either SIG_DFL or SIG_IGN on exec().
681 * However, if any signal handlers were established on alternate
682 * link maps before the primary link map has been initialized,
683 * then inform the kernel of the new sigacthandler.
684 */
685 void
686 signal_init()
687 {
688 uberdata_t *udp = curthread->ul_uberdata;
689 struct sigaction *sap;
690 struct sigaction act;
691 rwlock_t *rwlp;
692 int sig;
693
694 for (sig = 0; sig < NSIG; sig++) {
695 rwlp = &udp->siguaction[sig].sig_lock;
696 rwlp->rwlock_magic = RWL_MAGIC;
697 rwlp->mutex.mutex_flag = LOCK_INITED;
698 rwlp->mutex.mutex_magic = MUTEX_MAGIC;
699 sap = &udp->siguaction[sig].sig_uaction;
700 if (sap->sa_sigaction != SIG_DFL &&
701 sap->sa_sigaction != SIG_IGN &&
702 __sigaction(sig, NULL, &act) == 0 &&
703 act.sa_sigaction != SIG_DFL &&
704 act.sa_sigaction != SIG_IGN) {
705 act = *sap;
706 act.sa_flags &= ~SA_NODEFER;
707 act.sa_sigaction = udp->sigacthandler;
708 act.sa_mask = maskset;
709 (void) __sigaction(sig, &act, NULL);
710 }
711 }
712 }
713
714 /*
715 * Common code for cancelling self in _sigcancel() and pthread_cancel().
716 * First record the fact that a cancellation is pending.
717 * Then, if cancellation is disabled or if we are holding unprotected
718 * libc locks, just return to defer the cancellation.
719 * Then, if we are at a cancellation point (ul_cancelable) just
720 * return and let _canceloff() do the exit.
721 * Else exit immediately if async mode is in effect.
722 */
723 void
724 do_sigcancel(void)
725 {
726 ulwp_t *self = curthread;
727
728 ASSERT(self->ul_critical == 0);
729 ASSERT(self->ul_sigdefer == 0);
730 self->ul_cancel_pending = 1;
731 if (self->ul_cancel_async &&
732 !self->ul_cancel_disabled &&
733 self->ul_libc_locks == 0 &&
734 !self->ul_cancelable)
735 pthread_exit(PTHREAD_CANCELED);
736 set_cancel_pending_flag(self, 0);
737 }
738
739 /*
740 * Set up the SIGCANCEL handler for threads cancellation,
741 * needed only when we have more than one thread,
742 * or the SIGAIOCANCEL handler for aio cancellation,
743 * called when aio is initialized, in __uaio_init().
744 */
745 void
746 setup_cancelsig(int sig)
747 {
748 uberdata_t *udp = curthread->ul_uberdata;
749 rwlock_t *rwlp = &udp->siguaction[sig].sig_lock;
750 struct sigaction act;
751
752 ASSERT(sig == SIGCANCEL || sig == SIGAIOCANCEL);
753 lrw_rdlock(rwlp);
754 act = udp->siguaction[sig].sig_uaction;
755 lrw_unlock(rwlp);
756 if (act.sa_sigaction == SIG_DFL ||
757 act.sa_sigaction == SIG_IGN)
758 act.sa_flags = SA_SIGINFO;
759 else {
760 act.sa_flags |= SA_SIGINFO;
761 act.sa_flags &= ~(SA_NODEFER | SA_RESETHAND | SA_RESTART);
762 }
763 act.sa_sigaction = udp->sigacthandler;
764 act.sa_mask = maskset;
765 (void) __sigaction(sig, &act, NULL);
766 }