*/
#include <stdio.h>
+#include <stdlib.h>
#include <signal.h>
#ifdef mach /* KLUDGE: #ifdef on lowercase symbols? Ick. -- WHN 19990904 */
*
* However, some signals need special handling, e.g.
*
- * o the SIGSEGV (for Linux) or SIGBUS (for FreeBSD) used by the
+ * o the SIGSEGV (for e.g. Linux) or SIGBUS (for e.g. FreeBSD) used by the
* garbage collector to detect violations of write protection,
* because some cases of such signals (e.g. GC-related violations of
* write protection) are handled at C level and never passed on to
* FREE_INTERRUPT_CONTEXT_INDEX? If so, we should say so. And
* perhaps yes, unbind_to_here() really would be clearer and less
* fragile.. */
+ /* dan (2001.08.10) thinks the above supposition is probably correct */
unbind();
#ifdef reg_ALLOC
}
#ifdef QSHOW_SIGNALS
- FSHOW((stderr, "in interrupt_handle_now(%d, info, context)\n", signal));
+ FSHOW((stderr,
+ "/entering interrupt_handle_now(%d, info, context)\n",
+ signal));
#endif
if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
{
undo_fake_foreign_function_call(context);
}
+
+#ifdef QSHOW_SIGNALS
+ FSHOW((stderr,
+ "/returning from interrupt_handle_now(%d, info, context)\n",
+ signal));
+#endif
}
static void
#endif
#ifndef __i386__
-/* This function gets called from the SIGSEGV (Linux) or SIGBUS (BSD)
- * handler. Here we check whether the signal was due to treading on
- * the mprotect()ed zone - and if so, arrange for a GC to happen.
- */
+/* This function gets called from the SIGSEGV (for e.g. Linux or
+ * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
+ * whether the signal was due to treading on the mprotect()ed zone -
+ * and if so, arrange for a GC to happen. */
boolean
interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
{
* noise to install handlers
*/
-/* Install a special low-level handler for signal; or if handler is
- * SIG_DFL, remove any special handling for signal. */
+/*
+ * what low-level signal handlers looked like before
+ * undoably_install_low_level_interrupt_handler() got involved
+ */
+struct low_level_signal_handler_state {
+ int was_modified;
+ void (*handler)(int, siginfo_t*, void*);
+} old_low_level_signal_handler_states[NSIG];
+
void
-interrupt_install_low_level_handler (int signal,
- void handler(int, siginfo_t*, void*))
+uninstall_low_level_interrupt_handlers_atexit(void)
+{
+ int signal;
+ for (signal = 0; signal < NSIG; ++signal) {
+ struct low_level_signal_handler_state
+ *old_low_level_signal_handler_state =
+ old_low_level_signal_handler_states + signal;
+ if (old_low_level_signal_handler_state->was_modified) {
+ struct sigaction sa;
+ sa.sa_sigaction = old_low_level_signal_handler_state->handler;
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_SIGINFO | SA_RESTART;
+ sigaction(signal, &sa, NULL);
+ }
+ }
+}
+
+/* Undoably install a special low-level handler for signal; or if
+ * handler is SIG_DFL, remove any special handling for signal.
+ *
+ * The "undoably" aspect is because we also arrange with atexit() for
+ * the handler to be restored to its old value. This is for tidiness:
+ * it shouldn't matter much ordinarily, but it does remove a window
+ * where e.g. memory fault signals (SIGSEGV or SIGBUS, which in
+ * ordinary operation of SBCL are sent to the generational garbage
+ * collector, then possibly onward to Lisp code) or SIGINT (which is
+ * ordinarily passed to Lisp code) could otherwise be handled
+ * bizarrely/brokenly because the Lisp code would try to deal with
+ * them using machinery (like stream output buffers) which has already
+ * been dismantled. */
+void
+undoably_install_low_level_interrupt_handler (int signal,
+ void handler(int,
+ siginfo_t*,
+ void*))
{
struct sigaction sa;
+ struct low_level_signal_handler_state *old_low_level_signal_handler_state =
+ old_low_level_signal_handler_states + signal;
+
+ if (0 > signal || signal >= NSIG) {
+ lose("bad signal number %d", signal);
+ }
sa.sa_sigaction = handler;
sigemptyset(&sa.sa_mask);
sigaddset_blockable(&sa.sa_mask);
sa.sa_flags = SA_SIGINFO | SA_RESTART;
- sigaction(signal, &sa, NULL);
+ /* In the case of interrupt handlers which are modified more than
+ * once, we only save the original unmodified copy. */
+ if (!old_low_level_signal_handler_state->was_modified) {
+ struct sigaction *old_handler =
+ (struct sigaction*) &old_low_level_signal_handler_state->handler;
+ old_low_level_signal_handler_state->was_modified = 1;
+ sigaction(signal, &sa, old_handler);
+ } else {
+ sigaction(signal, &sa, NULL);
+ }
+
interrupt_low_level_handlers[signal] =
- (ARE_SAME_HANDLER(handler,SIG_DFL) ? 0 : handler);
+ (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
}
/* This is called from Lisp. */
sigset_t old, new;
union interrupt_handler oldhandler;
- FSHOW((stderr, "entering POSIX install_handler(%d, ..)\n", signal));
+ FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
sigemptyset(&new);
sigaddset(&new, signal);
sigemptyset(&new);
sigaddset_blockable(&new);
- FSHOW((stderr, "interrupt_low_level_handlers[signal]=%d\n",
+ FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%d\n",
interrupt_low_level_handlers[signal]));
if (interrupt_low_level_handlers[signal]==0) {
if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
sigprocmask(SIG_SETMASK, &old, 0);
- FSHOW((stderr, "leaving POSIX install_handler(%d, ..)\n", signal));
+ FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
return (unsigned long)oldhandler.lisp;
}
{
int i;
+ SHOW("entering interrupt_init()");
+
+ /* Set up for recovery from any installed low-level handlers. */
+ atexit(&uninstall_low_level_interrupt_handlers_atexit);
+
+ /* Set up high level handler information. */
for (i = 0; i < NSIG; i++) {
interrupt_handlers[i].c =
/* (The cast here blasts away the distinction between
* 3-argument form is expected.) */
(void (*)(int, siginfo_t*, void*))SIG_DFL;
}
+
+ SHOW("returning from interrupt_init()");
}
projects / sbcl.git / blobdiff