/* -----------------------------------------------------------------------------
- * $Id: Signals.c,v 1.5 1999/03/02 20:01:55 sof Exp $
+ * $Id: Signals.c,v 1.30 2002/12/05 14:20:55 stolz Exp $
*
* (c) The GHC Team, 1998-1999
*
*
* ---------------------------------------------------------------------------*/
+/* This is non-Posix-compliant.
+ #include "PosixSource.h"
+*/
#include "Rts.h"
#include "SchedAPI.h"
+#include "Schedule.h"
#include "Signals.h"
#include "RtsUtils.h"
#include "RtsFlags.h"
#include "StablePriv.h"
+#ifdef alpha_TARGET_ARCH
+# include <machine/fpu.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+#include <stdlib.h>
+
#ifndef mingw32_TARGET_OS
#ifndef PAR
+/* SUP: The type of handlers is a little bit, well, doubtful... */
static StgInt *handlers = NULL; /* Dynamically grown array of signal handlers */
static StgInt nHandlers = 0; /* Size of handlers array */
+static nat n_haskell_handlers = 0;
+
#define N_PENDING_HANDLERS 16
StgPtr pending_handler_buf[N_PENDING_HANDLERS];
StgInt nocldstop = 0;
/* -----------------------------------------------------------------------------
- Allocate/resize the table of signal handlers.
- -------------------------------------------------------------------------- */
+ * Allocate/resize the table of signal handlers.
+ * -------------------------------------------------------------------------- */
static void
more_handlers(I_ sig)
{
- I_ i;
+ StgInt i;
if (sig < nHandlers)
return;
if (handlers == NULL)
- handlers = (I_ *) malloc((sig + 1) * sizeof(I_));
+ handlers = (StgInt *) malloc((sig + 1) * sizeof(StgInt));
else
- handlers = (I_ *) realloc(handlers, (sig + 1) * sizeof(I_));
+ handlers = (StgInt *) realloc(handlers, (sig + 1) * sizeof(StgInt));
if (handlers == NULL) {
- fflush(stdout);
- fprintf(stderr, "VM exhausted (in more_handlers)\n");
- exit(EXIT_FAILURE);
+ // don't fflush(stdout); WORKAROUND bug in Linux glibc
+ barf("VM exhausted (in more_handlers)");
}
for(i = nHandlers; i <= sig; i++)
- /* Fill in the new slots with default actions */
+ // Fill in the new slots with default actions
handlers[i] = STG_SIG_DFL;
nHandlers = sig + 1;
}
/* -----------------------------------------------------------------------------
- Low-level signal handler
+ * SIGCONT handler
+ *
+ * It seems that shells tend to put stdin back into blocking mode
+ * following a suspend/resume of the process. Here we arrange to put
+ * it back into non-blocking mode. We don't do anything to
+ * stdout/stderr because these handles don't get put into non-blocking
+ * mode at all - see the comments on stdout/stderr in PrelHandle.hsc.
+ * -------------------------------------------------------------------------- */
+
+static void
+cont_handler(int sig STG_UNUSED)
+{
+ setNonBlockingFd(0);
+}
- Places the requested handler on a stack of pending handlers to be
- started up at the next context switch.
- -------------------------------------------------------------------------- */
+/* -----------------------------------------------------------------------------
+ * Low-level signal handler
+ *
+ * Places the requested handler on a stack of pending handlers to be
+ * started up at the next context switch.
+ * -------------------------------------------------------------------------- */
static void
generic_handler(int sig)
either. However, we have to schedule a new thread somehow.
It's probably ok to request a context switch and allow the
- scheduler to start the handler thread, but how to we
+ scheduler to start the handler thread, but how do we
communicate this to the scheduler?
We need some kind of locking, but with low overhead (i.e. no
circumstances, depending on the signal.
*/
- *next_pending_handler++ = deRefStablePtr(handlers[sig]);
+ *next_pending_handler++ = deRefStablePtr((StgStablePtr)handlers[sig]);
- /* stack full? */
+ // stack full?
if (next_pending_handler == &pending_handler_buf[N_PENDING_HANDLERS]) {
- barf("too many pending signals");
+ barf("too many pending signals");
}
- /* re-establish the signal handler, and carry on */
+ // re-establish the signal handler, and carry on
sigemptyset(&signals);
sigaddset(&signals, sig);
sigprocmask(SIG_UNBLOCK, &signals, NULL);
+
+ // *always* do the SIGCONT handler, even if the user overrides it.
+ if (sig == SIGCONT) {
+ cont_handler(sig);
+ }
+
+ context_switch = 1;
}
/* -----------------------------------------------------------------------------
- Blocking/Unblocking of the user signals
- -------------------------------------------------------------------------- */
+ * Blocking/Unblocking of the user signals
+ * -------------------------------------------------------------------------- */
static sigset_t userSignals;
static sigset_t savedSignals;
sigprocmask(SIG_SETMASK, &savedSignals, NULL);
}
+rtsBool
+anyUserHandlers(void)
+{
+ return n_haskell_handlers != 0;
+}
+
+void
+awaitUserSignals(void)
+{
+ while (!signals_pending() && !interrupted) {
+ pause();
+ }
+}
/* -----------------------------------------------------------------------------
- Install a Haskell signal handler.
- -------------------------------------------------------------------------- */
+ * Install a Haskell signal handler.
+ * -------------------------------------------------------------------------- */
-StgInt
-sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
+int
+stg_sig_install(int sig, int spi, StgStablePtr *handler, void *mask)
{
- sigset_t signals;
+ sigset_t signals, osignals;
struct sigaction action;
StgInt previous_spi;
- /* Block the signal until we figure out what to do */
- /* Count on this to fail if the signal number is invalid */
- if(sig < 0 || sigemptyset(&signals) || sigaddset(&signals, sig) ||
- sigprocmask(SIG_BLOCK, &signals, NULL))
- return STG_SIG_ERR;
-
+ // Block the signal until we figure out what to do
+ // Count on this to fail if the signal number is invalid
+ if (sig < 0 || sigemptyset(&signals) ||
+ sigaddset(&signals, sig) || sigprocmask(SIG_BLOCK, &signals, &osignals)) {
+ return STG_SIG_ERR;
+ }
+
more_handlers(sig);
previous_spi = handlers[sig];
sigdelset(&userSignals, sig);
action.sa_handler = SIG_DFL;
break;
+
case STG_SIG_HAN:
- handlers[sig] = (I_)handler;
+ case STG_SIG_RST:
+ handlers[sig] = (StgInt)*handler;
sigaddset(&userSignals, sig);
action.sa_handler = generic_handler;
+ if (spi == STG_SIG_RST) {
+ action.sa_flags = SA_RESETHAND;
+ }
+ n_haskell_handlers++;
break;
+
default:
- barf("sig_install: bad spi");
+ barf("stg_sig_install: bad spi");
}
- if (mask != 0)
- action.sa_mask = *mask;
+ if (mask != NULL)
+ action.sa_mask = *(sigset_t *)mask;
else
sigemptyset(&action.sa_mask);
- action.sa_flags = sig == SIGCHLD && nocldstop ? SA_NOCLDSTOP : 0;
+ action.sa_flags |= sig == SIGCHLD && nocldstop ? SA_NOCLDSTOP : 0;
if (sigaction(sig, &action, NULL) ||
- sigprocmask(SIG_UNBLOCK, &signals, NULL))
+ sigprocmask(SIG_SETMASK, &osignals, NULL))
{
- /* need to return an error code, so avoid a stable pointer leak
- * by freeing the previous handler if there was one.
- */
- if (previous_spi >= 0) {
- freeStablePtr(handlers[sig]);
- }
- return STG_SIG_ERR;
+ // need to return an error code, so avoid a stable pointer leak
+ // by freeing the previous handler if there was one.
+ if (previous_spi >= 0) {
+ freeStablePtr(stgCast(StgStablePtr,handlers[sig]));
+ n_haskell_handlers--;
+ }
+ return STG_SIG_ERR;
+ }
+
+ if (previous_spi == STG_SIG_DFL || previous_spi == STG_SIG_IGN
+ || previous_spi == STG_SIG_ERR) {
+ return previous_spi;
+ } else {
+ *handler = (StgStablePtr)previous_spi;
+ return STG_SIG_HAN;
}
-
- return previous_spi;
}
/* -----------------------------------------------------------------------------
- Creating new threads for the pending signal handlers.
- -------------------------------------------------------------------------- */
-
+ * Creating new threads for the pending signal handlers.
+ * -------------------------------------------------------------------------- */
void
-start_signal_handlers(void)
+startSignalHandlers(void)
{
blockUserSignals();
next_pending_handler--;
- /* create*Thread puts the thread on the head of the runnable
- * queue, hence it will be run next. Poor man's priority
- * scheduling.
- */
- createIOThread(RtsFlags.GcFlags.initialStkSize,
- (StgClosure *) *next_pending_handler);
+ scheduleThread(
+ createIOThread(RtsFlags.GcFlags.initialStkSize,
+ (StgClosure *) *next_pending_handler));
}
unblockUserSignals();
}
-#else /* PAR */
+/* ----------------------------------------------------------------------------
+ * Mark signal handlers during GC.
+ *
+ * We do this rather than trying to start all the signal handlers
+ * prior to GC, because that requires extra heap for the new threads.
+ * Signals must be blocked (see blockUserSignals() above) during GC to
+ * avoid race conditions.
+ * -------------------------------------------------------------------------- */
+
+void
+markSignalHandlers (evac_fn evac)
+{
+ StgPtr *p;
+
+ p = next_pending_handler;
+ while (p != pending_handler_buf) {
+ p--;
+ evac((StgClosure **)p);
+ }
+}
+
+#else // PAR
StgInt
-sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
+stg_sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
{
- fflush(stdout);
- fprintf(stderr,
- "No signal handling support in a parallel implementation.\n");
- exit(EXIT_FAILURE);
+ // don't fflush(stdout); WORKAROUND bug in Linux glibc
+ barf("no signal handling support in a parallel implementation");
}
void
-start_signal_handlers(void)
+startSignalHandlers(void)
{
}
#endif
+/* -----------------------------------------------------------------------------
+ * SIGINT handler.
+ *
+ * We like to shutdown nicely after receiving a SIGINT, write out the
+ * stats, write profiling info, close open files and flush buffers etc.
+ * -------------------------------------------------------------------------- */
+#ifdef SMP
+pthread_t startup_guy;
+#endif
+
+static void
+shutdown_handler(int sig STG_UNUSED)
+{
+#ifdef SMP
+ // if I'm a worker thread, send this signal to the guy who
+ // originally called startupHaskell(). Since we're handling
+ // the signal, it won't be a "send to all threads" type of signal
+ // (according to the POSIX threads spec).
+ if (pthread_self() != startup_guy) {
+ pthread_kill(startup_guy, sig);
+ return;
+ }
+#endif
+
+ // If we're already trying to interrupt the RTS, terminate with
+ // extreme prejudice. So the first ^C tries to exit the program
+ // cleanly, and the second one just kills it.
+ if (interrupted) {
+ exit(EXIT_INTERRUPTED);
+ } else {
+ interruptStgRts();
+ }
+}
+
+/* -----------------------------------------------------------------------------
+ * Install default signal handlers.
+ *
+ * The RTS installs a default signal handler for catching
+ * SIGINT, so that we can perform an orderly shutdown.
+ *
+ * Haskell code may install their own SIGINT handler, which is
+ * fine, provided they're so kind as to put back the old one
+ * when they de-install.
+ *
+ * In addition to handling SIGINT, the RTS also handles SIGFPE
+ * by ignoring it. Apparently IEEE requires floating-point
+ * exceptions to be ignored by default, but alpha-dec-osf3
+ * doesn't seem to do so.
+ * -------------------------------------------------------------------------- */
+void
+initDefaultHandlers()
+{
+ struct sigaction action,oact;
+
+#ifdef SMP
+ startup_guy = pthread_self();
+#endif
+
+ // install the SIGINT handler
+ action.sa_handler = shutdown_handler;
+ sigemptyset(&action.sa_mask);
+ action.sa_flags = 0;
+ if (sigaction(SIGINT, &action, &oact) != 0) {
+ prog_belch("warning: failed to install SIGINT handler");
+ }
+
+#ifndef cygwin32_TARGET_OS
+ siginterrupt(SIGINT, 1); // isn't this the default? --SDM
+#endif
+
+ // install the SIGCONT handler
+ action.sa_handler = cont_handler;
+ sigemptyset(&action.sa_mask);
+ action.sa_flags = 0;
+ if (sigaction(SIGCONT, &action, &oact) != 0) {
+ prog_belch("warning: failed to install SIGCONT handler");
+ }
+
+ // install the SIGFPE handler
+
+ // In addition to handling SIGINT, also handle SIGFPE by ignoring it.
+ // Apparently IEEE requires floating-point exceptions to be ignored by
+ // default, but alpha-dec-osf3 doesn't seem to do so.
+
+ // Commented out by SDM 2/7/2002: this causes an infinite loop on
+ // some architectures when an integer division by zero occurs: we
+ // don't recover from the floating point exception, and the
+ // program just generates another one immediately.
+#if 0
+ action.sa_handler = SIG_IGN;
+ sigemptyset(&action.sa_mask);
+ action.sa_flags = 0;
+ if (sigaction(SIGFPE, &action, &oact) != 0) {
+ prog_belch("warning: failed to install SIGFPE handler");
+ }
+#endif
+
+#ifdef alpha_TARGET_ARCH
+ ieee_set_fp_control(0);
+#endif
+}
+
#endif /*! mingw32_TARGET_OS */