2 * interrupt-handling magic
6 * This software is part of the SBCL system. See the README file for
9 * This software is derived from the CMU CL system, which was
10 * written at Carnegie Mellon University and released into the
11 * public domain. The software is in the public domain and is
12 * provided with absolutely no warranty. See the COPYING and CREDITS
13 * files for more information.
17 /* As far as I can tell, what's going on here is:
19 * In the case of most signals, when Lisp asks us to handle the
20 * signal, the outermost handler (the one actually passed to UNIX) is
21 * either interrupt_handle_now(..) or maybe_now_maybe_later(..).
22 * In that case, the Lisp-level handler is stored in interrupt_handlers[..]
23 * and interrupt_low_level_handlers[..] is cleared.
25 * However, some signals need special handling, e.g.
27 * o the SIGSEGV (for e.g. Linux) or SIGBUS (for e.g. FreeBSD) used by the
28 * garbage collector to detect violations of write protection,
29 * because some cases of such signals (e.g. GC-related violations of
30 * write protection) are handled at C level and never passed on to
31 * Lisp. For such signals, we still store any Lisp-level handler
32 * in interrupt_handlers[..], but for the outermost handle we use
33 * the value from interrupt_low_level_handlers[..], instead of the
34 * ordinary interrupt_handle_now(..) or interrupt_handle_later(..).
36 * o the SIGTRAP (Linux/Alpha) which Lisp code uses to handle breakpoints,
37 * pseudo-atomic sections, and some classes of error (e.g. "function
38 * not defined"). This never goes anywhere near the Lisp handlers at all.
39 * See runtime/alpha-arch.c and code/signal.lisp
41 * - WHN 20000728, dan 20010128 */
53 #include "interrupt.h"
62 #include "genesis/fdefn.h"
63 #include "genesis/simple-fun.h"
65 void run_deferred_handler(struct interrupt_data *data, void *v_context) ;
66 static void store_signal_data_for_later (struct interrupt_data *data,
67 void *handler, int signal,
69 os_context_t *context);
70 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
72 extern volatile lispobj all_threads_lock;
73 extern volatile int countdown_to_gc;
76 * This is a workaround for some slightly silly Linux/GNU Libc
77 * behaviour: glibc defines sigset_t to support 1024 signals, which is
78 * more than the kernel. This is usually not a problem, but becomes
79 * one when we want to save a signal mask from a ucontext, and restore
80 * it later into another ucontext: the ucontext is allocated on the
81 * stack by the kernel, so copying a libc-sized sigset_t into it will
82 * overflow and cause other data on the stack to be corrupted */
84 #define REAL_SIGSET_SIZE_BYTES ((NSIG/8))
86 void sigaddset_blockable(sigset_t *s)
90 sigaddset(s, SIGQUIT);
91 sigaddset(s, SIGPIPE);
92 sigaddset(s, SIGALRM);
95 sigaddset(s, SIGTSTP);
96 sigaddset(s, SIGCHLD);
98 sigaddset(s, SIGXCPU);
99 sigaddset(s, SIGXFSZ);
100 sigaddset(s, SIGVTALRM);
101 sigaddset(s, SIGPROF);
102 sigaddset(s, SIGWINCH);
103 sigaddset(s, SIGUSR1);
104 sigaddset(s, SIGUSR2);
105 #ifdef LISP_FEATURE_SB_THREAD
106 sigaddset(s, SIG_STOP_FOR_GC);
107 sigaddset(s, SIG_INTERRUPT_THREAD);
111 /* When we catch an internal error, should we pass it back to Lisp to
112 * be handled in a high-level way? (Early in cold init, the answer is
113 * 'no', because Lisp is still too brain-dead to handle anything.
114 * After sufficient initialization has been completed, the answer
116 boolean internal_errors_enabled = 0;
118 struct interrupt_data * global_interrupt_data;
120 /* this is used from Lisp in toplevel.lisp, replacing an older
121 * (sigsetmask 0) - we'd like to find out when the signal mask is
124 /* This check was introduced in 0.8.4.x and some day will go away
125 * again unless we find a way to trigger it */
127 void warn_when_signals_masked ()
129 /* and as a side-eeffect, unmask them */
134 sigprocmask(SIG_SETMASK,&new,&old);
135 for(i=1; i<NSIG; i++) {
136 if(sigismember(&old,i)) {
138 "Warning: signal %d is masked: this is unexpected\n",i);
143 fprintf(stderr,"If this version of SBCL is less than three months old, please report this.\nOtherwise, please try a newer version first\n. Reset signal mask.\n");
148 * utility routines used by various signal handlers
152 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
154 #ifndef LISP_FEATURE_X86
158 /* Build a fake stack frame or frames */
160 current_control_frame_pointer =
161 (lispobj *)(*os_context_register_addr(context, reg_CSP));
162 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
163 == current_control_frame_pointer) {
164 /* There is a small window during call where the callee's
165 * frame isn't built yet. */
166 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
167 == FUN_POINTER_LOWTAG) {
168 /* We have called, but not built the new frame, so
169 * build it for them. */
170 current_control_frame_pointer[0] =
171 *os_context_register_addr(context, reg_OCFP);
172 current_control_frame_pointer[1] =
173 *os_context_register_addr(context, reg_LRA);
174 current_control_frame_pointer += 8;
175 /* Build our frame on top of it. */
176 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
179 /* We haven't yet called, build our frame as if the
180 * partial frame wasn't there. */
181 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
184 /* We can't tell whether we are still in the caller if it had to
185 * allocate a stack frame due to stack arguments. */
186 /* This observation provoked some past CMUCL maintainer to ask
187 * "Can anything strange happen during return?" */
190 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
193 current_control_stack_pointer = current_control_frame_pointer + 8;
195 current_control_frame_pointer[0] = oldcont;
196 current_control_frame_pointer[1] = NIL;
197 current_control_frame_pointer[2] =
198 (lispobj)(*os_context_register_addr(context, reg_CODE));
203 fake_foreign_function_call(os_context_t *context)
206 struct thread *thread=arch_os_get_current_thread();
208 /* Get current Lisp state from context. */
210 dynamic_space_free_pointer =
211 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
213 if ((long)dynamic_space_free_pointer & 1) {
214 lose("dead in fake_foreign_function_call, context = %x", context);
219 current_binding_stack_pointer =
220 (lispobj *)(*os_context_register_addr(context, reg_BSP));
223 build_fake_control_stack_frames(thread,context);
225 /* Do dynamic binding of the active interrupt context index
226 * and save the context in the context array. */
228 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
230 if (context_index >= MAX_INTERRUPTS) {
231 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
234 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
235 make_fixnum(context_index + 1),thread);
237 thread->interrupt_contexts[context_index] = context;
239 /* no longer in Lisp now */
240 foreign_function_call_active = 1;
243 /* blocks all blockable signals. If you are calling from a signal handler,
244 * the usual signal mask will be restored from the context when the handler
245 * finishes. Otherwise, be careful */
248 undo_fake_foreign_function_call(os_context_t *context)
250 struct thread *thread=arch_os_get_current_thread();
251 /* Block all blockable signals. */
254 sigaddset_blockable(&block);
255 sigprocmask(SIG_BLOCK, &block, 0);
257 /* going back into Lisp */
258 foreign_function_call_active = 0;
260 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
264 /* Put the dynamic space free pointer back into the context. */
265 *os_context_register_addr(context, reg_ALLOC) =
266 (unsigned long) dynamic_space_free_pointer;
270 /* a handler for the signal caused by execution of a trap opcode
271 * signalling an internal error */
273 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
276 lispobj context_sap = 0;
278 fake_foreign_function_call(context);
280 /* Allocate the SAP object while the interrupts are still
282 if (internal_errors_enabled) {
283 context_sap = alloc_sap(context);
286 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
288 if (internal_errors_enabled) {
289 SHOW("in interrupt_internal_error");
291 /* Display some rudimentary debugging information about the
292 * error, so that even if the Lisp error handler gets badly
293 * confused, we have a chance to determine what's going on. */
294 describe_internal_error(context);
296 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
297 continuable ? T : NIL);
299 describe_internal_error(context);
300 /* There's no good way to recover from an internal error
301 * before the Lisp error handling mechanism is set up. */
302 lose("internal error too early in init, can't recover");
304 undo_fake_foreign_function_call(context); /* blocks signals again */
306 arch_skip_instruction(context);
311 interrupt_handle_pending(os_context_t *context)
313 struct thread *thread;
314 struct interrupt_data *data;
316 thread=arch_os_get_current_thread();
317 data=thread->interrupt_data;
318 /* FIXME I'm not altogether sure this is appropriate if we're
319 * here as the result of a pseudo-atomic */
320 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
322 /* restore the saved signal mask from the original signal (the
323 * one that interrupted us during the critical section) into the
324 * os_context for the signal we're currently in the handler for.
325 * This should ensure that when we return from the handler the
326 * blocked signals are unblocked */
328 memcpy(os_context_sigmask_addr(context), &data->pending_mask,
329 REAL_SIGSET_SIZE_BYTES);
331 sigemptyset(&data->pending_mask);
332 /* This will break on sparc linux: the deferred handler really wants
333 * to be called with a void_context */
334 run_deferred_handler(data,(void *)context);
338 * the two main signal handlers:
339 * interrupt_handle_now(..)
340 * maybe_now_maybe_later(..)
342 * to which we have added interrupt_handle_now_handler(..). Why?
343 * Well, mostly because the SPARC/Linux platform doesn't quite do
344 * signals the way we want them done. The third argument in the
345 * handler isn't filled in by the kernel properly, so we fix it up
346 * ourselves in the arch_os_get_context(..) function; however, we only
347 * want to do this when we first hit the handler, and not when
348 * interrupt_handle_now(..) is being called from some other handler
349 * (when the fixup will already have been done). -- CSR, 2002-07-23
353 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
355 os_context_t *context = (os_context_t*)void_context;
356 struct thread *thread=arch_os_get_current_thread();
357 #ifndef LISP_FEATURE_X86
358 boolean were_in_lisp;
360 union interrupt_handler handler;
362 #ifdef LISP_FEATURE_LINUX
363 /* Under Linux on some architectures, we appear to have to restore
364 the FPU control word from the context, as after the signal is
365 delivered we appear to have a null FPU control word. */
366 os_restore_fp_control(context);
368 handler = thread->interrupt_data->interrupt_handlers[signal];
370 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
374 #ifndef LISP_FEATURE_X86
375 were_in_lisp = !foreign_function_call_active;
379 fake_foreign_function_call(context);
384 "/entering interrupt_handle_now(%d, info, context)\n",
388 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
390 /* This can happen if someone tries to ignore or default one
391 * of the signals we need for runtime support, and the runtime
392 * support decides to pass on it. */
393 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
395 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
396 /* Once we've decided what to do about contexts in a
397 * return-elsewhere world (the original context will no longer
398 * be available; should we copy it or was nobody using it anyway?)
399 * then we should convert this to return-elsewhere */
401 /* CMUCL comment said "Allocate the SAPs while the interrupts
402 * are still disabled.". I (dan, 2003.08.21) assume this is
403 * because we're not in pseudoatomic and allocation shouldn't
404 * be interrupted. In which case it's no longer an issue as
405 * all our allocation from C now goes through a PA wrapper,
406 * but still, doesn't hurt */
408 lispobj info_sap,context_sap = alloc_sap(context);
409 info_sap = alloc_sap(info);
410 /* Allow signals again. */
411 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
414 SHOW("calling Lisp-level handler");
417 funcall3(handler.lisp,
424 SHOW("calling C-level handler");
427 /* Allow signals again. */
428 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
430 (*handler.c)(signal, info, void_context);
433 #ifndef LISP_FEATURE_X86
437 undo_fake_foreign_function_call(context); /* block signals again */
442 "/returning from interrupt_handle_now(%d, info, context)\n",
447 /* This is called at the end of a critical section if the indications
448 * are that some signal was deferred during the section. Note that as
449 * far as C or the kernel is concerned we dealt with the signal
450 * already; we're just doing the Lisp-level processing now that we
454 run_deferred_handler(struct interrupt_data *data, void *v_context) {
455 (*(data->pending_handler))
456 (data->pending_signal,&(data->pending_info), v_context);
457 data->pending_handler=0;
461 maybe_defer_handler(void *handler, struct interrupt_data *data,
462 int signal, siginfo_t *info, os_context_t *context)
464 struct thread *thread=arch_os_get_current_thread();
465 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
466 store_signal_data_for_later(data,handler,signal,info,context);
467 SetSymbolValue(INTERRUPT_PENDING, T,thread);
470 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
471 * actually use its argument for anything on x86, so this branch
472 * may succeed even when context is null (gencgc alloc()) */
474 #ifndef LISP_FEATURE_X86
475 (!foreign_function_call_active) &&
477 arch_pseudo_atomic_atomic(context)) {
478 store_signal_data_for_later(data,handler,signal,info,context);
479 arch_set_pseudo_atomic_interrupted(context);
485 store_signal_data_for_later (struct interrupt_data *data, void *handler,
487 siginfo_t *info, os_context_t *context)
489 data->pending_handler = handler;
490 data->pending_signal = signal;
492 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
494 /* the signal mask in the context (from before we were
495 * interrupted) is copied to be restored when
496 * run_deferred_handler happens. Then the usually-blocked
497 * signals are added to the mask in the context so that we are
498 * running with blocked signals when the handler returns */
499 sigemptyset(&(data->pending_mask));
500 memcpy(&(data->pending_mask),
501 os_context_sigmask_addr(context),
502 REAL_SIGSET_SIZE_BYTES);
503 sigaddset_blockable(os_context_sigmask_addr(context));
505 /* this is also called from gencgc alloc(), in which case
506 * there has been no signal and is therefore no context. */
509 sigaddset_blockable(&new);
510 sigprocmask(SIG_BLOCK,&new,&(data->pending_mask));
516 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
518 os_context_t *context = arch_os_get_context(&void_context);
519 struct thread *thread=arch_os_get_current_thread();
520 struct interrupt_data *data=thread->interrupt_data;
521 #ifdef LISP_FEATURE_LINUX
522 os_restore_fp_control(context);
524 if(maybe_defer_handler(interrupt_handle_now,data,
525 signal,info,context))
527 interrupt_handle_now(signal, info, context);
531 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
533 os_context_t *context = arch_os_get_context(&void_context);
534 struct thread *thread=arch_os_get_current_thread();
535 struct interrupt_data *data=thread->interrupt_data;
538 if(maybe_defer_handler(sig_stop_for_gc_handler,data,
539 signal,info,context)){
542 /* need the context stored so it can have registers scavenged */
543 fake_foreign_function_call(context);
545 get_spinlock(&all_threads_lock,thread->pid);
547 thread->state=STATE_STOPPED;
548 release_spinlock(&all_threads_lock);
549 kill(thread->pid,SIGSTOP);
551 undo_fake_foreign_function_call(context);
555 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
557 os_context_t *context = arch_os_get_context(&void_context);
558 interrupt_handle_now(signal, info, context);
562 * stuff to detect and handle hitting the GC trigger
565 #ifndef LISP_FEATURE_GENCGC
566 /* since GENCGC has its own way to record trigger */
568 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
570 if (current_auto_gc_trigger == NULL)
573 void *badaddr=arch_get_bad_addr(signal,info,context);
574 return (badaddr >= (void *)current_auto_gc_trigger &&
575 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
580 /* manipulate the signal context and stack such that when the handler
581 * returns, it will call function instead of whatever it was doing
585 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
586 extern void post_signal_tramp(void);
587 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
589 void * fun=native_pointer(function);
590 char *code = &(((struct simple_fun *) fun)->code);
592 /* Build a stack frame showing `interrupted' so that the
593 * user's backtrace makes (as much) sense (as usual) */
594 #ifdef LISP_FEATURE_X86
595 /* Suppose the existence of some function that saved all
596 * registers, called call_into_lisp, then restored GP registers and
597 * returned. We shortcut this: fake the stack that call_into_lisp
598 * would see, then arrange to have it called directly. post_signal_tramp
599 * is the second half of this function
601 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
603 *(sp-14) = post_signal_tramp; /* return address for call_into_lisp */
604 *(sp-13) = function; /* args for call_into_lisp : function*/
605 *(sp-12) = 0; /* arg array */
606 *(sp-11) = 0; /* no. args */
607 /* this order matches that used in POPAD */
608 *(sp-10)=*os_context_register_addr(context,reg_EDI);
609 *(sp-9)=*os_context_register_addr(context,reg_ESI);
610 /* this gets overwritten again before it's used, anyway */
611 *(sp-8)=*os_context_register_addr(context,reg_EBP);
612 *(sp-7)=0 ; /* POPAD doesn't set ESP, but expects a gap for it anyway */
613 *(sp-6)=*os_context_register_addr(context,reg_EBX);
615 *(sp-5)=*os_context_register_addr(context,reg_EDX);
616 *(sp-4)=*os_context_register_addr(context,reg_ECX);
617 *(sp-3)=*os_context_register_addr(context,reg_EAX);
618 *(sp-2)=*os_context_register_addr(context,reg_EBP);
619 *(sp-1)=*os_context_pc_addr(context);
622 struct thread *th=arch_os_get_current_thread();
623 build_fake_control_stack_frames(th,context);
626 #ifdef LISP_FEATURE_X86
627 *os_context_pc_addr(context) = call_into_lisp;
628 *os_context_register_addr(context,reg_ECX) = 0;
629 *os_context_register_addr(context,reg_EBP) = sp-2;
630 *os_context_register_addr(context,reg_ESP) = sp-14;
632 /* this much of the calling convention is common to all
634 *os_context_pc_addr(context) = code;
635 *os_context_register_addr(context,reg_NARGS) = 0;
636 *os_context_register_addr(context,reg_LIP) = code;
637 *os_context_register_addr(context,reg_CFP) =
638 current_control_frame_pointer;
640 #ifdef ARCH_HAS_NPC_REGISTER
641 *os_context_npc_addr(context) =
642 4 + *os_context_pc_addr(context);
644 #ifdef LISP_FEATURE_SPARC
645 *os_context_register_addr(context,reg_CODE) =
646 fun + FUN_POINTER_LOWTAG;
650 #ifdef LISP_FEATURE_SB_THREAD
651 void handle_rt_signal(int num, siginfo_t *info, void *v_context)
653 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
654 struct thread *th=arch_os_get_current_thread();
655 struct interrupt_data *data=
656 th ? th->interrupt_data : global_interrupt_data;
657 if(maybe_defer_handler(handle_rt_signal,data,num,info,context)){
660 arrange_return_to_lisp_function(context,info->si_value.sival_int);
664 boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){
665 struct thread *th=arch_os_get_current_thread();
666 /* note the os_context hackery here. When the signal handler returns,
667 * it won't go back to what it was doing ... */
668 if(addr>=(void *)CONTROL_STACK_GUARD_PAGE(th) &&
669 addr<(void *)(CONTROL_STACK_GUARD_PAGE(th)+os_vm_page_size)) {
670 /* we hit the end of the control stack. disable protection
671 * temporarily so the error handler has some headroom */
672 protect_control_stack_guard_page(th->pid,0L);
674 arrange_return_to_lisp_function
675 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
681 #ifndef LISP_FEATURE_GENCGC
682 /* This function gets called from the SIGSEGV (for e.g. Linux or
683 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
684 * whether the signal was due to treading on the mprotect()ed zone -
685 * and if so, arrange for a GC to happen. */
686 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
689 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
691 os_context_t *context=(os_context_t *) void_context;
692 struct thread *th=arch_os_get_current_thread();
693 struct interrupt_data *data=
694 th ? th->interrupt_data : global_interrupt_data;
696 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
697 clear_auto_gc_trigger();
698 if(!maybe_defer_handler
699 (interrupt_maybe_gc_int,data,signal,info,void_context))
700 interrupt_maybe_gc_int(signal,info,void_context);
708 /* this is also used by gencgc, in alloc() */
710 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
713 os_context_t *context=(os_context_t *) void_context;
714 fake_foreign_function_call(context);
715 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
716 * which case we will be running with no gc trigger barrier
717 * thing for a while. But it shouldn't be long until the end
718 * of WITHOUT-GCING. */
721 sigaddset_blockable(&new);
722 /* enable signals before calling into Lisp */
723 sigprocmask(SIG_UNBLOCK,&new,0);
724 funcall0(SymbolFunction(SUB_GC));
725 undo_fake_foreign_function_call(context);
731 * noise to install handlers
735 undoably_install_low_level_interrupt_handler (int signal,
741 struct thread *th=arch_os_get_current_thread();
742 struct interrupt_data *data=
743 th ? th->interrupt_data : global_interrupt_data;
745 if (0 > signal || signal >= NSIG) {
746 lose("bad signal number %d", signal);
749 sa.sa_sigaction = handler;
750 sigemptyset(&sa.sa_mask);
751 sigaddset_blockable(&sa.sa_mask);
752 sa.sa_flags = SA_SIGINFO | SA_RESTART;
753 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
754 if((signal==SIG_MEMORY_FAULT)
755 #ifdef SIG_INTERRUPT_THREAD
756 || (signal==SIG_INTERRUPT_THREAD)
759 sa.sa_flags|= SA_ONSTACK;
762 sigaction(signal, &sa, NULL);
763 data->interrupt_low_level_handlers[signal] =
764 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
767 /* This is called from Lisp. */
769 install_handler(int signal, void handler(int, siginfo_t*, void*))
773 union interrupt_handler oldhandler;
774 struct thread *th=arch_os_get_current_thread();
775 struct interrupt_data *data=
776 th ? th->interrupt_data : global_interrupt_data;
778 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
781 sigaddset(&new, signal);
782 sigprocmask(SIG_BLOCK, &new, &old);
785 sigaddset_blockable(&new);
787 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%d\n",
788 interrupt_low_level_handlers[signal]));
789 if (data->interrupt_low_level_handlers[signal]==0) {
790 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
791 ARE_SAME_HANDLER(handler, SIG_IGN)) {
792 sa.sa_sigaction = handler;
793 } else if (sigismember(&new, signal)) {
794 sa.sa_sigaction = maybe_now_maybe_later;
796 sa.sa_sigaction = interrupt_handle_now_handler;
799 sigemptyset(&sa.sa_mask);
800 sigaddset_blockable(&sa.sa_mask);
801 sa.sa_flags = SA_SIGINFO | SA_RESTART;
802 sigaction(signal, &sa, NULL);
805 oldhandler = data->interrupt_handlers[signal];
806 data->interrupt_handlers[signal].c = handler;
808 sigprocmask(SIG_SETMASK, &old, 0);
810 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
812 return (unsigned long)oldhandler.lisp;
819 SHOW("entering interrupt_init()");
820 global_interrupt_data=calloc(sizeof(struct interrupt_data), 1);
822 /* Set up high level handler information. */
823 for (i = 0; i < NSIG; i++) {
824 global_interrupt_data->interrupt_handlers[i].c =
825 /* (The cast here blasts away the distinction between
826 * SA_SIGACTION-style three-argument handlers and
827 * signal(..)-style one-argument handlers, which is OK
828 * because it works to call the 1-argument form where the
829 * 3-argument form is expected.) */
830 (void (*)(int, siginfo_t*, void*))SIG_DFL;
833 SHOW("returning from interrupt_init()");