--- /dev/null
+/*
+ * Console control handler support.
+ *
+ */
+#include "Rts.h"
+#include <windows.h>
+#include "ConsoleHandler.h"
+#include "SchedAPI.h"
+#include "Schedule.h"
+#include "RtsUtils.h"
+#include "RtsFlags.h"
+#include "AsyncIO.h"
+#include "RtsSignals.h"
+
+extern int stg_InstallConsoleEvent(int action, StgStablePtr *handler);
+
+static BOOL WINAPI shutdown_handler(DWORD dwCtrlType);
+static BOOL WINAPI generic_handler(DWORD dwCtrlType);
+
+static rtsBool deliver_event = rtsTrue;
+static StgInt console_handler = STG_SIG_DFL;
+
+static HANDLE hConsoleEvent = INVALID_HANDLE_VALUE;
+
+#define N_PENDING_EVENTS 16
+StgInt stg_pending_events = 0; /* number of undelivered events */
+DWORD stg_pending_buf[N_PENDING_EVENTS]; /* their associated event numbers. */
+
+/*
+ * Function: initUserSignals()
+ *
+ * Initialize the console handling substrate.
+ */
+void
+initUserSignals(void)
+{
+ stg_pending_events = 0;
+ console_handler = STG_SIG_DFL;
+ if (hConsoleEvent == INVALID_HANDLE_VALUE) {
+ hConsoleEvent =
+ CreateEvent ( NULL, /* default security attributes */
+ TRUE, /* manual-reset event */
+ FALSE, /* initially non-signalled */
+ NULL); /* no name */
+ }
+ return;
+}
+
+/*
+ * Function: shutdown_handler()
+ *
+ * Local function that performs the default handling of Ctrl+C kind
+ * events; gently shutting down the RTS
+ *
+ * To repeat Signals.c remark -- user code may choose to override the
+ * default handler. Which is fine, assuming they put back the default
+ * handler when/if they de-install the custom handler.
+ *
+ */
+static BOOL WINAPI shutdown_handler(DWORD dwCtrlType)
+{
+ switch (dwCtrlType) {
+
+ case CTRL_CLOSE_EVENT:
+ /* see generic_handler() comment re: this event */
+ return FALSE;
+ case CTRL_C_EVENT:
+ case CTRL_BREAK_EVENT:
+
+ // 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 (sched_state >= SCHED_INTERRUPTING) {
+ stg_exit(EXIT_INTERRUPTED);
+ } else {
+ interruptStgRts();
+ /* Cheesy pulsing of an event to wake up a waiting RTS thread, if any */
+ abandonRequestWait();
+ resetAbandonRequestWait();
+ }
+ return TRUE;
+
+ /* shutdown + logoff events are not handled here. */
+ default:
+ return FALSE;
+ }
+}
+
+
+/*
+ * Function: initDefaultHandlers()
+ *
+ * Install any default signal/console handlers. Currently we install a
+ * Ctrl+C handler that shuts down the RTS in an orderly manner.
+ */
+void initDefaultHandlers(void)
+{
+ if ( !SetConsoleCtrlHandler(shutdown_handler, TRUE) ) {
+ errorBelch("warning: failed to install default console handler");
+ }
+}
+
+
+/*
+ * Function: blockUserSignals()
+ *
+ * Temporarily block the delivery of further console events. Needed to
+ * avoid race conditions when GCing the stack of outstanding handlers or
+ * when emptying the stack by running the handlers.
+ *
+ */
+void
+blockUserSignals(void)
+{
+ deliver_event = rtsFalse;
+}
+
+
+/*
+ * Function: unblockUserSignals()
+ *
+ * The inverse of blockUserSignals(); re-enable the deliver of console events.
+ */
+void
+unblockUserSignals(void)
+{
+ deliver_event = rtsTrue;
+}
+
+
+/*
+ * Function: awaitUserSignals()
+ *
+ * Wait for the next console event. Currently a NOP (returns immediately.)
+ */
+void awaitUserSignals(void)
+{
+ return;
+}
+
+
+/*
+ * Function: startSignalHandlers()
+ *
+ * Run the handlers associated with the stacked up console events. Console
+ * event delivery is blocked for the duration of this call.
+ */
+void startSignalHandlers(Capability *cap)
+{
+ StgStablePtr handler;
+
+ if (console_handler < 0) {
+ return;
+ }
+
+ blockUserSignals();
+ ACQUIRE_LOCK(&sched_mutex);
+
+ handler = deRefStablePtr((StgStablePtr)console_handler);
+ while (stg_pending_events > 0) {
+ stg_pending_events--;
+ scheduleThread(cap,
+ createIOThread(cap,
+ RtsFlags.GcFlags.initialStkSize,
+ rts_apply(cap,
+ (StgClosure *)handler,
+ rts_mkInt(cap,
+ stg_pending_buf[stg_pending_events]))));
+ }
+
+ RELEASE_LOCK(&sched_mutex);
+ unblockUserSignals();
+}
+
+/*
+ * Function: markSignalHandlers()
+ *
+ * Evacuate the handler stack. _Assumes_ that console event delivery
+ * has already been blocked.
+ */
+void markSignalHandlers (evac_fn evac)
+{
+ if (console_handler >= 0) {
+ StgPtr p = deRefStablePtr((StgStablePtr)console_handler);
+ evac((StgClosure**)(void *)&p);
+ }
+}
+
+
+/*
+ * Function: generic_handler()
+ *
+ * Local function which handles incoming console event (done in a sep OS thread),
+ * recording the event in stg_pending_events.
+ */
+static BOOL WINAPI generic_handler(DWORD dwCtrlType)
+{
+ ACQUIRE_LOCK(&sched_mutex);
+
+ /* Ultra-simple -- up the counter + signal a switch. */
+ switch(dwCtrlType) {
+ case CTRL_CLOSE_EVENT:
+ /* Don't support the delivery of this event; if we
+ * indicate that we've handled it here and the Haskell handler
+ * doesn't take proper action (e.g., terminate the OS process),
+ * the user of the app will be unable to kill/close it. Not
+ * good, so disable the delivery for now.
+ */
+ return FALSE;
+ default:
+ if (!deliver_event) return TRUE;
+
+ if ( stg_pending_events < N_PENDING_EVENTS ) {
+ stg_pending_buf[stg_pending_events] = dwCtrlType;
+ stg_pending_events++;
+ }
+ /* Cheesy pulsing of an event to wake up a waiting RTS thread, if any */
+ abandonRequestWait();
+ resetAbandonRequestWait();
+ return TRUE;
+ }
+
+ RELEASE_LOCK(&sched_mutex);
+}
+
+
+/*
+ * Function: rts_InstallConsoleEvent()
+ *
+ * Install/remove a console event handler.
+ */
+int
+rts_InstallConsoleEvent(int action, StgStablePtr *handler)
+{
+ StgInt previous_hdlr = console_handler;
+
+ switch (action) {
+ case STG_SIG_IGN:
+ console_handler = STG_SIG_IGN;
+ if ( !SetConsoleCtrlHandler(NULL, TRUE) ) {
+ errorBelch("warning: unable to ignore console events");
+ }
+ break;
+ case STG_SIG_DFL:
+ console_handler = STG_SIG_IGN;
+ if ( !SetConsoleCtrlHandler(NULL, FALSE) ) {
+ errorBelch("warning: unable to restore default console event handling");
+ }
+ break;
+ case STG_SIG_HAN:
+ console_handler = (StgInt)*handler;
+ if ( previous_hdlr < 0 ) {
+ /* Only install generic_handler() once */
+ if ( !SetConsoleCtrlHandler(generic_handler, TRUE) ) {
+ errorBelch("warning: unable to install console event handler");
+ }
+ }
+ break;
+ }
+
+ if (previous_hdlr == STG_SIG_DFL ||
+ previous_hdlr == STG_SIG_IGN) {
+ return previous_hdlr;
+ } else {
+ *handler = (StgStablePtr)previous_hdlr;
+ return STG_SIG_HAN;
+ }
+}
+
+/*
+ * Function: rts_HandledConsoleEvent()
+ *
+ * Signal that a Haskell console event handler has completed its run.
+ * The explicit notification that a Haskell handler has completed is
+ * required to better handle the delivery of Ctrl-C/Break events whilst
+ * an async worker thread is handling a read request on stdin. The
+ * Win32 console implementation will abort such a read request when Ctrl-C
+ * is delivered. That leaves the worker thread in a bind: should it
+ * abandon the request (the Haskell thread reading from stdin has been
+ * thrown an exception to signal the delivery of Ctrl-C & hence have
+ * aborted the I/O request) or simply ignore the aborted read and retry?
+ * (the Haskell thread reading from stdin isn't concerned with the
+ * delivery and handling of Ctrl-C.) With both scenarios being
+ * possible, the worker thread needs to be told -- that is, did the
+ * console event handler cause the IO request to be abandoned?
+ *
+ */
+void
+rts_ConsoleHandlerDone(int ev)
+{
+ if ( (DWORD)ev == CTRL_BREAK_EVENT ||
+ (DWORD)ev == CTRL_C_EVENT ) {
+ /* only these two cause stdin system calls to abort.. */
+ SetEvent(hConsoleEvent); /* event is manual-reset */
+ Sleep(0); /* yield */
+ ResetEvent(hConsoleEvent); /* turn it back off again */
+ }
+}
+
+/*
+ * Function: rts_waitConsoleHandlerCompletion()
+ *
+ * Esoteric entry point used by worker thread that got woken
+ * up as part Ctrl-C delivery.
+ */
+int
+rts_waitConsoleHandlerCompletion()
+{
+ /* As long as the worker doesn't need to do a multiple wait,
+ * let's keep this HANDLE private to this 'module'.
+ */
+ return (WaitForSingleObject(hConsoleEvent, INFINITE) == WAIT_OBJECT_0);
+}
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