protect console handler against concurrent access (#1922)

[ghc-hetmet.git] / rts / win32 / ConsoleHandler.c

diff --git a/rts/win32/ConsoleHandler.c b/rts/win32/ConsoleHandler.c
index a2de74b..76ebea0 100644 (file)
--- a/rts/win32/ConsoleHandler.c
+++ b/rts/win32/ConsoleHandler.c
@@ -264,8 +264,13 @@ rts_InstallConsoleEvent(int action, StgStablePtr *handler)
        }
        break;
     case STG_SIG_HAN:
+#ifdef THREADED_RTS
+        // handler is stored in an MVar in the threaded RTS
+       console_handler = STG_SIG_HAN;
+#else
        console_handler = (StgInt)*handler;
-       if ( previous_hdlr < 0 ) {
+#endif
+       if (previous_hdlr < 0 || previous_hdlr == STG_SIG_HAN) {
          /* Only install generic_handler() once */
          if ( !SetConsoleCtrlHandler(generic_handler, TRUE) ) {
            errorBelch("warning: unable to install console event handler");
@@ -275,10 +280,13 @@ rts_InstallConsoleEvent(int action, StgStablePtr *handler)
     }
     
     if (previous_hdlr == STG_SIG_DFL || 
-       previous_hdlr == STG_SIG_IGN) {
+       previous_hdlr == STG_SIG_IGN ||
+        previous_hdlr == STG_SIG_HAN) {
        return previous_hdlr;
     } else {
-       *handler = (StgStablePtr)previous_hdlr;
+       if (handler != NULL) {
+            *handler = (StgStablePtr)previous_hdlr;
+        }
        return STG_SIG_HAN;
     }
 }