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 lispobj all_threads_lock;
73 extern 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 /* don't block STOP_FOR_GC, we need to be able to interrupt threads
107 * for GC purposes even when they are blocked on queues etc */
108 sigaddset(s, SIG_INTERRUPT_THREAD);
112 /* When we catch an internal error, should we pass it back to Lisp to
113 * be handled in a high-level way? (Early in cold init, the answer is
114 * 'no', because Lisp is still too brain-dead to handle anything.
115 * After sufficient initialization has been completed, the answer
117 boolean internal_errors_enabled = 0;
119 struct interrupt_data * global_interrupt_data;
123 * utility routines used by various signal handlers
127 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
129 #ifndef LISP_FEATURE_X86
133 /* Build a fake stack frame or frames */
135 current_control_frame_pointer =
136 (lispobj *)(*os_context_register_addr(context, reg_CSP));
137 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
138 == current_control_frame_pointer) {
139 /* There is a small window during call where the callee's
140 * frame isn't built yet. */
141 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
142 == FUN_POINTER_LOWTAG) {
143 /* We have called, but not built the new frame, so
144 * build it for them. */
145 current_control_frame_pointer[0] =
146 *os_context_register_addr(context, reg_OCFP);
147 current_control_frame_pointer[1] =
148 *os_context_register_addr(context, reg_LRA);
149 current_control_frame_pointer += 8;
150 /* Build our frame on top of it. */
151 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
154 /* We haven't yet called, build our frame as if the
155 * partial frame wasn't there. */
156 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
159 /* We can't tell whether we are still in the caller if it had to
160 * allocate a stack frame due to stack arguments. */
161 /* This observation provoked some past CMUCL maintainer to ask
162 * "Can anything strange happen during return?" */
165 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
168 current_control_stack_pointer = current_control_frame_pointer + 8;
170 current_control_frame_pointer[0] = oldcont;
171 current_control_frame_pointer[1] = NIL;
172 current_control_frame_pointer[2] =
173 (lispobj)(*os_context_register_addr(context, reg_CODE));
178 fake_foreign_function_call(os_context_t *context)
181 struct thread *thread=arch_os_get_current_thread();
183 /* Get current Lisp state from context. */
185 dynamic_space_free_pointer =
186 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
188 if ((long)dynamic_space_free_pointer & 1) {
189 lose("dead in fake_foreign_function_call, context = %x", context);
194 current_binding_stack_pointer =
195 (lispobj *)(*os_context_register_addr(context, reg_BSP));
198 build_fake_control_stack_frames(thread,context);
200 /* Do dynamic binding of the active interrupt context index
201 * and save the context in the context array. */
203 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
205 if (context_index >= MAX_INTERRUPTS) {
206 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
209 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
210 make_fixnum(context_index + 1),thread);
212 thread->interrupt_contexts[context_index] = context;
214 /* no longer in Lisp now */
215 foreign_function_call_active = 1;
218 /* blocks all blockable signals. If you are calling from a signal handler,
219 * the usual signal mask will be restored from the context when the handler
220 * finishes. Otherwise, be careful */
223 undo_fake_foreign_function_call(os_context_t *context)
225 struct thread *thread=arch_os_get_current_thread();
226 /* Block all blockable signals. */
229 sigaddset_blockable(&block);
230 sigprocmask(SIG_BLOCK, &block, 0);
232 /* going back into Lisp */
233 foreign_function_call_active = 0;
235 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
239 /* Put the dynamic space free pointer back into the context. */
240 *os_context_register_addr(context, reg_ALLOC) =
241 (unsigned long) dynamic_space_free_pointer;
245 /* a handler for the signal caused by execution of a trap opcode
246 * signalling an internal error */
248 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
251 lispobj context_sap = 0;
253 fake_foreign_function_call(context);
255 /* Allocate the SAP object while the interrupts are still
257 if (internal_errors_enabled) {
258 context_sap = alloc_sap(context);
261 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
263 if (internal_errors_enabled) {
264 SHOW("in interrupt_internal_error");
266 /* Display some rudimentary debugging information about the
267 * error, so that even if the Lisp error handler gets badly
268 * confused, we have a chance to determine what's going on. */
269 describe_internal_error(context);
271 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
272 continuable ? T : NIL);
274 describe_internal_error(context);
275 /* There's no good way to recover from an internal error
276 * before the Lisp error handling mechanism is set up. */
277 lose("internal error too early in init, can't recover");
279 undo_fake_foreign_function_call(context);
281 arch_skip_instruction(context);
286 interrupt_handle_pending(os_context_t *context)
288 struct thread *thread;
289 struct interrupt_data *data;
291 thread=arch_os_get_current_thread();
292 data=thread->interrupt_data;
293 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
295 /* restore the saved signal mask from the original signal (the
296 * one that interrupted us during the critical section) into the
297 * os_context for the signal we're currently in the handler for.
298 * This should ensure that when we return from the handler the
299 * blocked signals are unblocked */
301 memcpy(os_context_sigmask_addr(context), &data->pending_mask,
302 REAL_SIGSET_SIZE_BYTES);
304 sigemptyset(&data->pending_mask);
305 /* This will break on sparc linux: the deferred handler really wants
306 * to be called with a void_context */
307 run_deferred_handler(data,(void *)context);
311 * the two main signal handlers:
312 * interrupt_handle_now(..)
313 * maybe_now_maybe_later(..)
315 * to which we have added interrupt_handle_now_handler(..). Why?
316 * Well, mostly because the SPARC/Linux platform doesn't quite do
317 * signals the way we want them done. The third argument in the
318 * handler isn't filled in by the kernel properly, so we fix it up
319 * ourselves in the arch_os_get_context(..) function; however, we only
320 * want to do this when we first hit the handler, and not when
321 * interrupt_handle_now(..) is being called from some other handler
322 * (when the fixup will already have been done). -- CSR, 2002-07-23
326 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
328 os_context_t *context = (os_context_t*)void_context;
329 struct thread *thread=arch_os_get_current_thread();
331 boolean were_in_lisp;
333 union interrupt_handler handler;
335 #ifdef LISP_FEATURE_LINUX
336 /* Under Linux on some architectures, we appear to have to restore
337 the FPU control word from the context, as after the signal is
338 delivered we appear to have a null FPU control word. */
339 os_restore_fp_control(context);
341 handler = thread->interrupt_data->interrupt_handlers[signal];
343 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
348 were_in_lisp = !foreign_function_call_active;
352 fake_foreign_function_call(context);
357 "/entering interrupt_handle_now(%d, info, context)\n",
361 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
363 /* This can happen if someone tries to ignore or default one
364 * of the signals we need for runtime support, and the runtime
365 * support decides to pass on it. */
366 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
368 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
369 /* Once we've decided what to do about contexts in a
370 * return-elsewhere world (the original context will no longer
371 * be available; should we copy it or was nobody using it anyway?)
372 * then we should convert this to return-elsewhere */
374 /* CMUCL comment said "Allocate the SAPs while the interrupts
375 * are still disabled.". I (dan, 2003.08.21) assume this is
376 * because we're not in pseudoatomic and allocation shouldn't
377 * be interrupted. In which case it's no longer an issue as
378 * all our allocation from C now goes through a PA wrapper,
379 * but still, doesn't hurt */
381 lispobj info_sap,context_sap = alloc_sap(context);
382 info_sap = alloc_sap(info);
383 /* Allow signals again. */
384 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
387 SHOW("calling Lisp-level handler");
390 funcall3(handler.lisp,
397 SHOW("calling C-level handler");
400 /* Allow signals again. */
401 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
403 (*handler.c)(signal, info, void_context);
410 undo_fake_foreign_function_call(context);
415 "/returning from interrupt_handle_now(%d, info, context)\n",
420 /* This is called at the end of a critical section if the indications
421 * are that some signal was deferred during the section. Note that as
422 * far as C or the kernel is concerned we dealt with the signal
423 * already; we're just doing the Lisp-level processing now that we
427 run_deferred_handler(struct interrupt_data *data, void *v_context) {
428 fprintf(stderr,"Running deferred handler for %d, 0x%x\n",
429 data->pending_signal, data->pending_handler);
430 (*(data->pending_handler))
431 (data->pending_signal,&(data->pending_info), v_context);
435 maybe_defer_handler(void *handler, struct interrupt_data *data,
436 int signal, siginfo_t *info, os_context_t *context)
438 struct thread *thread=arch_os_get_current_thread();
439 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
440 store_signal_data_for_later(data,handler,signal,info,context);
441 SetSymbolValue(INTERRUPT_PENDING, T,thread);
444 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
445 * actually use its argument for anything on x86, so this branch
446 * may succeed even when context is null (gencgc alloc()) */
449 (!foreign_function_call_active) &&
451 arch_pseudo_atomic_atomic(context)) {
452 store_signal_data_for_later(data,handler,signal,info,context);
453 arch_set_pseudo_atomic_interrupted(context);
459 store_signal_data_for_later (struct interrupt_data *data, void *handler,
461 siginfo_t *info, os_context_t *context)
463 data->pending_handler = handler;
464 data->pending_signal = signal;
466 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
468 /* the signal mask in the context (from before we were
469 * interrupted) is copied to be restored when
470 * run_deferred_handler happens. Then the usually-blocked
471 * signals are added to the mask in the context so that we are
472 * running with blocked signals when the handler returns */
473 sigemptyset(&(data->pending_mask));
474 memcpy(&(data->pending_mask),
475 os_context_sigmask_addr(context),
476 REAL_SIGSET_SIZE_BYTES);
477 sigaddset_blockable(os_context_sigmask_addr(context));
479 /* this is also called from gencgc alloc(), in which case
480 * there has been no signal and is therefore no context. */
483 sigaddset_blockable(&new);
484 sigprocmask(SIG_BLOCK,&new,&(data->pending_mask));
490 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
492 os_context_t *context = arch_os_get_context(&void_context);
493 struct thread *thread=arch_os_get_current_thread();
494 struct interrupt_data *data=thread->interrupt_data;
495 #ifdef LISP_FEATURE_LINUX
496 os_restore_fp_control(context);
498 if(maybe_defer_handler(interrupt_handle_now,data,
499 signal,info,context))
501 interrupt_handle_now(signal, info, context);
505 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
507 os_context_t *context = arch_os_get_context(&void_context);
508 struct thread *thread=arch_os_get_current_thread();
509 struct interrupt_data *data=thread->interrupt_data;
512 if(maybe_defer_handler(sig_stop_for_gc_handler,data,
513 signal,info,context)){
517 sigaddset_blockable(&block);
518 sigprocmask(SIG_BLOCK, &block, 0);
520 /* need the context stored so it can have registers scavenged */
521 fake_foreign_function_call(context);
523 get_spinlock(&all_threads_lock,thread->pid);
525 release_spinlock(&all_threads_lock);
526 kill(getpid(),SIGSTOP);
528 undo_fake_foreign_function_call(context);
532 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
534 os_context_t *context = arch_os_get_context(&void_context);
535 interrupt_handle_now(signal, info, context);
539 * stuff to detect and handle hitting the GC trigger
542 #ifndef LISP_FEATURE_GENCGC
543 /* since GENCGC has its own way to record trigger */
545 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
547 if (current_auto_gc_trigger == NULL)
550 void *badaddr=arch_get_bad_addr(signal,info,context);
551 return (badaddr >= (void *)current_auto_gc_trigger &&
552 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
557 /* manipulate the signal context and stack such that when the handler
558 * returns, it will call function instead of whatever it was doing
562 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
563 extern void post_signal_tramp(void);
564 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
566 void * fun=native_pointer(function);
567 char *code = &(((struct simple_fun *) fun)->code);
569 /* Build a stack frame showing `interrupted' so that the
570 * user's backtrace makes (as much) sense (as usual) */
571 #ifdef LISP_FEATURE_X86
572 /* Suppose the existence of some function that saved all
573 * registers, called call_into_lisp, then restored GP registers and
574 * returned. We shortcut this: fake the stack that call_into_lisp
575 * would see, then arrange to have it called directly. post_signal_tramp
576 * is the second half of this function
578 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
580 *(sp-14) = post_signal_tramp; /* return address for call_into_lisp */
581 *(sp-13) = function; /* args for call_into_lisp : function*/
582 *(sp-12) = 0; /* arg array */
583 *(sp-11) = 0; /* no. args */
584 /* this order matches that used in POPAD */
585 *(sp-10)=*os_context_register_addr(context,reg_EDI);
586 *(sp-9)=*os_context_register_addr(context,reg_ESI);
587 /* this gets overwritten again before it's used, anyway */
588 *(sp-8)=*os_context_register_addr(context,reg_EBP);
589 *(sp-7)=0 ; /* POPAD doesn't set ESP, but expects a gap for it anyway */
590 *(sp-6)=*os_context_register_addr(context,reg_EBX);
592 *(sp-5)=*os_context_register_addr(context,reg_EDX);
593 *(sp-4)=*os_context_register_addr(context,reg_ECX);
594 *(sp-3)=*os_context_register_addr(context,reg_EAX);
595 *(sp-2)=*os_context_register_addr(context,reg_EBP);
596 *(sp-1)=*os_context_pc_addr(context);
599 struct thread *th=arch_os_get_current_thread();
600 build_fake_control_stack_frames(th,context);
603 #ifdef LISP_FEATURE_X86
604 *os_context_pc_addr(context) = call_into_lisp;
605 *os_context_register_addr(context,reg_ECX) = 0;
606 *os_context_register_addr(context,reg_EBP) = sp-2;
607 *os_context_register_addr(context,reg_ESP) = sp-14;
609 /* this much of the calling convention is common to all
611 *os_context_pc_addr(context) = code;
612 *os_context_register_addr(context,reg_NARGS) = 0;
613 *os_context_register_addr(context,reg_LIP) = code;
614 *os_context_register_addr(context,reg_CFP) =
615 current_control_frame_pointer;
617 #ifdef ARCH_HAS_NPC_REGISTER
618 *os_context_npc_addr(context) =
619 4 + *os_context_pc_addr(context);
621 #ifdef LISP_FEATURE_SPARC
622 *os_context_register_addr(context,reg_CODE) =
623 fun + FUN_POINTER_LOWTAG;
627 #ifdef LISP_FEATURE_SB_THREAD
628 void handle_rt_signal(int num, siginfo_t *info, void *v_context)
630 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
631 struct thread *th=arch_os_get_current_thread();
632 struct interrupt_data *data=
633 th ? th->interrupt_data : global_interrupt_data;
634 if(maybe_defer_handler(handle_rt_signal,data,num,info,context)){
637 arrange_return_to_lisp_function(context,info->si_value.sival_int);
641 boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){
642 struct thread *th=arch_os_get_current_thread();
643 /* note the os_context hackery here. When the signal handler returns,
644 * it won't go back to what it was doing ... */
645 if(addr>=(void *)CONTROL_STACK_GUARD_PAGE(th) &&
646 addr<(void *)(CONTROL_STACK_GUARD_PAGE(th)+os_vm_page_size)) {
647 /* we hit the end of the control stack. disable protection
648 * temporarily so the error handler has some headroom */
649 protect_control_stack_guard_page(th->pid,0L);
651 arrange_return_to_lisp_function
652 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
658 #ifndef LISP_FEATURE_GENCGC
659 /* This function gets called from the SIGSEGV (for e.g. Linux or
660 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
661 * whether the signal was due to treading on the mprotect()ed zone -
662 * and if so, arrange for a GC to happen. */
663 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
666 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
668 os_context_t *context=(os_context_t *) void_context;
669 struct thread *th=arch_os_get_current_thread();
670 struct interrupt_data *data=
671 th ? th->interrupt_data : global_interrupt_data;
673 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
674 clear_auto_gc_trigger();
675 if(!maybe_defer_handler
676 (interrupt_maybe_gc_int,data,signal,info,void_context))
677 interrupt_maybe_gc_int(signal,info,void_context);
685 /* this is also used by from gencgc.c alloc() */
687 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
689 os_context_t *context=(os_context_t *) void_context;
690 fake_foreign_function_call(context);
691 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
692 * which case we will be running with no gc trigger barrier
693 * thing for a while. But it shouldn't be long until the end
694 * of WITHOUT-GCING. */
695 funcall0(SymbolFunction(SUB_GC));
696 undo_fake_foreign_function_call(context);
702 * noise to install handlers
706 undoably_install_low_level_interrupt_handler (int signal,
712 struct thread *th=arch_os_get_current_thread();
713 struct interrupt_data *data=
714 th ? th->interrupt_data : global_interrupt_data;
716 if (0 > signal || signal >= NSIG) {
717 lose("bad signal number %d", signal);
720 sa.sa_sigaction = handler;
721 sigemptyset(&sa.sa_mask);
722 sigaddset_blockable(&sa.sa_mask);
723 sa.sa_flags = SA_SIGINFO | SA_RESTART;
724 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
725 if((signal==SIG_MEMORY_FAULT)
726 #ifdef SIG_INTERRUPT_THREAD
727 || (signal==SIG_INTERRUPT_THREAD)
730 sa.sa_flags|= SA_ONSTACK;
733 sigaction(signal, &sa, NULL);
734 data->interrupt_low_level_handlers[signal] =
735 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
738 /* This is called from Lisp. */
740 install_handler(int signal, void handler(int, siginfo_t*, void*))
744 union interrupt_handler oldhandler;
745 struct thread *th=arch_os_get_current_thread();
746 struct interrupt_data *data=
747 th ? th->interrupt_data : global_interrupt_data;
749 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
752 sigaddset(&new, signal);
753 sigprocmask(SIG_BLOCK, &new, &old);
756 sigaddset_blockable(&new);
758 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%d\n",
759 interrupt_low_level_handlers[signal]));
760 if (data->interrupt_low_level_handlers[signal]==0) {
761 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
762 ARE_SAME_HANDLER(handler, SIG_IGN)) {
763 sa.sa_sigaction = handler;
764 } else if (sigismember(&new, signal)) {
765 sa.sa_sigaction = maybe_now_maybe_later;
767 sa.sa_sigaction = interrupt_handle_now_handler;
770 sigemptyset(&sa.sa_mask);
771 sigaddset_blockable(&sa.sa_mask);
772 sa.sa_flags = SA_SIGINFO | SA_RESTART;
773 sigaction(signal, &sa, NULL);
776 oldhandler = data->interrupt_handlers[signal];
777 data->interrupt_handlers[signal].c = handler;
779 sigprocmask(SIG_SETMASK, &old, 0);
781 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
783 return (unsigned long)oldhandler.lisp;
790 SHOW("entering interrupt_init()");
791 global_interrupt_data=calloc(sizeof(struct interrupt_data), 1);
793 /* Set up high level handler information. */
794 for (i = 0; i < NSIG; i++) {
795 global_interrupt_data->interrupt_handlers[i].c =
796 /* (The cast here blasts away the distinction between
797 * SA_SIGACTION-style three-argument handlers and
798 * signal(..)-style one-argument handlers, which is OK
799 * because it works to call the 1-argument form where the
800 * 3-argument form is expected.) */
801 (void (*)(int, siginfo_t*, void*))SIG_DFL;
804 SHOW("returning from interrupt_init()");