2 * Console control handler support.
7 #include "ConsoleHandler.h"
13 extern int stg_InstallConsoleEvent(int action, StgStablePtr *handler);
15 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType);
16 static BOOL WINAPI generic_handler(DWORD dwCtrlType);
18 static rtsBool deliver_event = rtsTrue;
19 static StgInt console_handler = STG_SIG_DFL;
21 #define N_PENDING_EVENTS 16
22 StgInt stg_pending_events = 0; /* number of undelivered events */
23 DWORD stg_pending_buf[N_PENDING_EVENTS]; /* their associated event numbers. */
26 * Function: initUserSignals()
28 * Initialize the console handling substrate.
33 stg_pending_events = 0;
34 console_handler = STG_SIG_DFL;
39 * Function: shutdown_handler()
41 * Local function that performs the default handling of Ctrl+C kind
42 * events; gently shutting down the RTS
44 * To repeat Signals.c remark -- user code may choose to override the
45 * default handler. Which is fine, assuming they put back the default
46 * handler when/if they de-install the custom handler.
49 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType)
53 case CTRL_CLOSE_EVENT:
54 /* see generic_handler() comment re: this event */
57 case CTRL_BREAK_EVENT:
59 // If we're already trying to interrupt the RTS, terminate with
60 // extreme prejudice. So the first ^C tries to exit the program
61 // cleanly, and the second one just kills it.
63 stg_exit(EXIT_INTERRUPTED);
69 /* shutdown + logoff events are not handled here. */
77 * Function: initDefaultHandlers()
79 * Install any default signal/console handlers. Currently we install a
80 * Ctrl+C handler that shuts down the RTS in an orderly manner.
82 void initDefaultHandlers(void)
84 if ( !SetConsoleCtrlHandler(shutdown_handler, TRUE) ) {
85 errorBelch("warning: failed to install default console handler");
91 * Function: blockUserSignals()
93 * Temporarily block the delivery of further console events. Needed to
94 * avoid race conditions when GCing the stack of outstanding handlers or
95 * when emptying the stack by running the handlers.
99 blockUserSignals(void)
101 deliver_event = rtsFalse;
106 * Function: unblockUserSignals()
108 * The inverse of blockUserSignals(); re-enable the deliver of console events.
111 unblockUserSignals(void)
113 deliver_event = rtsTrue;
118 * Function: awaitUserSignals()
120 * Wait for the next console event. Currently a NOP (returns immediately.)
122 void awaitUserSignals(void)
129 * Function: startSignalHandlers()
131 * Run the handlers associated with the stacked up console events. Console
132 * event delivery is blocked for the duration of this call.
134 void startSignalHandlers(void)
136 StgStablePtr handler;
138 if (console_handler < 0) {
143 handler = deRefStablePtr((StgStablePtr)console_handler);
144 while (stg_pending_events > 0) {
145 stg_pending_events--;
147 createIOThread(RtsFlags.GcFlags.initialStkSize,
148 rts_apply((StgClosure *)handler,
149 rts_mkInt(stg_pending_buf[stg_pending_events]))));
151 unblockUserSignals();
156 * Function: markSignalHandlers()
158 * Evacuate the handler stack. _Assumes_ that console event delivery
159 * has already been blocked.
161 void markSignalHandlers (evac_fn evac)
163 if (console_handler >= 0) {
164 StgPtr p = deRefStablePtr((StgStablePtr)console_handler);
165 evac((StgClosure**)&p);
171 * Function: handleSignalsInThisThread()
173 * Have current (OS) thread assume responsibility of handling console events/signals.
174 * Currently not used (by the console event handling code.)
176 void handleSignalsInThisThread(void)
182 * Function: generic_handler()
184 * Local function which handles incoming console event (done in a sep OS thread),
185 * recording the event in stg_pending_events.
187 static BOOL WINAPI generic_handler(DWORD dwCtrlType)
189 /* Ultra-simple -- up the counter + signal a switch. */
191 case CTRL_CLOSE_EVENT:
192 /* Don't support the delivery of this event; if we
193 * indicate that we've handled it here and the Haskell handler
194 * doesn't take proper action (e.g., terminate the OS process),
195 * the user of the app will be unable to kill/close it. Not
196 * good, so disable the delivery for now.
200 if ( stg_pending_events < N_PENDING_EVENTS ) {
201 stg_pending_buf[stg_pending_events] = dwCtrlType;
202 stg_pending_events++;
211 * Function: stg_InstallConsoleEvent()
213 * Install/remove a console event handler.
216 stg_InstallConsoleEvent(int action, StgStablePtr *handler)
218 StgInt previous_hdlr = console_handler;
222 console_handler = STG_SIG_IGN;
223 if ( !SetConsoleCtrlHandler(NULL, TRUE) ) {
224 errorBelch("warning: unable to ignore console events");
228 console_handler = STG_SIG_IGN;
229 if ( !SetConsoleCtrlHandler(NULL, FALSE) ) {
230 errorBelch("warning: unable to restore default console event handling");
234 console_handler = (StgInt)*handler;
235 if ( previous_hdlr < 0 ) {
236 /* Only install generic_handler() once */
237 if ( !SetConsoleCtrlHandler(generic_handler, TRUE) ) {
238 errorBelch("warning: unable to install console event handler");
244 if (previous_hdlr == STG_SIG_DFL ||
245 previous_hdlr == STG_SIG_IGN) {
246 return previous_hdlr;
248 *handler = (StgStablePtr)previous_hdlr;