2 * Console control handler support.
7 #include "ConsoleHandler.h"
12 #include "StablePriv.h"
14 extern int stg_InstallConsoleEvent(int action, StgStablePtr *handler);
16 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType);
17 static BOOL WINAPI generic_handler(DWORD dwCtrlType);
19 static rtsBool deliver_event = rtsTrue;
20 static StgInt console_handler = STG_SIG_DFL;
22 #define N_PENDING_EVENTS 16
23 StgInt stg_pending_events = 0; /* number of undelivered events */
24 DWORD stg_pending_buf[N_PENDING_EVENTS]; /* their associated event numbers. */
27 * Function: initUserSignals()
29 * Initialize the console handling substrate.
34 stg_pending_events = 0;
35 console_handler = STG_SIG_DFL;
40 * Function: shutdown_handler()
42 * Local function that performs the default handling of Ctrl+C kind
43 * events; gently shutting down the RTS
45 * To repeat Signals.c remark -- user code may choose to override the
46 * default handler. Which is fine, assuming they put back the default
47 * handler when/if they de-install the custom handler.
50 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType)
55 case CTRL_BREAK_EVENT:
56 case CTRL_CLOSE_EVENT:
58 // If we're already trying to interrupt the RTS, terminate with
59 // extreme prejudice. So the first ^C tries to exit the program
60 // cleanly, and the second one just kills it.
62 stg_exit(EXIT_INTERRUPTED);
68 /* shutdown + logoff events are not handled here. */
76 * Function: initDefaultHandlers()
78 * Install any default signal/console handlers. Currently we install a
79 * Ctrl+C handler that shuts down the RTS in an orderly manner.
81 void initDefaultHandlers(void)
83 if ( !SetConsoleCtrlHandler(shutdown_handler, TRUE) ) {
84 prog_belch("warning: failed to install default console handler");
90 * Function: blockUserSignals()
92 * Temporarily block the delivery of further console events. Needed to
93 * avoid race conditions when GCing the stack of outstanding handlers or
94 * when emptying the stack by running the handlers.
98 blockUserSignals(void)
100 deliver_event = rtsFalse;
105 * Function: unblockUserSignals()
107 * The inverse of blockUserSignals(); re-enable the deliver of console events.
110 unblockUserSignals(void)
112 deliver_event = rtsTrue;
117 * Function: awaitUserSignals()
119 * Wait for the next console event. Currently a NOP (returns immediately.)
121 void awaitUserSignals(void)
128 * Function: startSignalHandlers()
130 * Run the handlers associated with the stacked up console events. Console
131 * event delivery is blocked for the duration of this call.
133 void startSignalHandlers(void)
135 StgStablePtr handler;
137 if (console_handler < 0) {
142 handler = deRefStablePtr((StgStablePtr)console_handler);
143 while (stg_pending_events > 0) {
144 stg_pending_events--;
146 createIOThread(RtsFlags.GcFlags.initialStkSize,
147 rts_apply((StgClosure *)handler,
148 rts_mkInt(stg_pending_buf[stg_pending_events]))));
150 unblockUserSignals();
155 * Function: markSignalHandlers()
157 * Evacuate the handler stack. _Assumes_ that console event delivery
158 * has already been blocked.
160 void markSignalHandlers (evac_fn evac)
162 if (console_handler >= 0) {
163 StgPtr p = deRefStablePtr((StgStablePtr)console_handler);
164 evac((StgClosure**)&p);
170 * Function: handleSignalsInThisThread()
172 * Have current (OS) thread assume responsibility of handling console events/signals.
173 * Currently not used (by the console event handling code.)
175 void handleSignalsInThisThread(void)
181 * Function: generic_handler()
183 * Local function which handles incoming console event (done in a sep OS thread),
184 * recording the event in stg_pending_events.
186 static BOOL WINAPI generic_handler(DWORD dwCtrlType)
188 /* Ultra-simple -- up the counter + signal a switch. */
189 if ( stg_pending_events < N_PENDING_EVENTS ) {
190 stg_pending_buf[stg_pending_events] = dwCtrlType;
191 stg_pending_events++;
199 * Function: stg_InstallConsoleEvent()
201 * Install/remove a console event handler.
204 stg_InstallConsoleEvent(int action, StgStablePtr *handler)
206 StgInt previous_hdlr = console_handler;
210 console_handler = STG_SIG_IGN;
211 if ( !SetConsoleCtrlHandler(NULL, TRUE) ) {
212 prog_belch("warning: unable to ignore console events");
216 console_handler = STG_SIG_IGN;
217 if ( !SetConsoleCtrlHandler(NULL, FALSE) ) {
218 prog_belch("warning: unable to restore default console event handling");
222 console_handler = (StgInt)*handler;
223 if ( previous_hdlr < 0 ) {
224 /* Only install generic_handler() once */
225 if ( !SetConsoleCtrlHandler(generic_handler, TRUE) ) {
226 prog_belch("warning: unable to install console event handler");
232 if (previous_hdlr == STG_SIG_DFL ||
233 previous_hdlr == STG_SIG_IGN) {
234 return previous_hdlr;
236 *handler = (StgStablePtr)previous_hdlr;