+ IGNORE-SIGNAL to ignore synchronous signals

+ HANDLE-DEFAULT-SIGNAL to re-install default signal handler for
  synchronous signals

scsh/scsh-interfaces.scm

@@ -437,9 +437,9 @@
 (define-interface scsh-signals-interface
   (export signal-process
 	  signal-process-group
-	  ;; JMG: this syscalls doesn't cooperate with the thread-system 
+	  ;; JMG: this syscall doesn't cooperate with the thread-system 
 	  ;;	  pause-until-interrupt	  
-	  itimer  ;; now defined in low-interrupt as a artificial interrupt
+	  itimer  ;; now defined in low-interrupt as an artificial interrupt
 ))
 
 
@@ -1061,6 +1061,9 @@
 	  set-interrupt-handler
 	  interrupt-handler
 
+          ignore-signal
+          handle-signal-default
+
 	  ;; reexported from low-interrupt
 	  interrupt/alrm interrupt/alarm
 	  interrupt/int  interrupt/keyboard

scsh/sighandlers.scm

@@ -204,6 +204,12 @@
 	  (call-interrupt-handler interrupt)
 	  (make-interrupt-pending interrupt))
       (lp event))))
+
+;;; Dealing with synchronous signals
+
+(import-lambda-definition ignore-signal (sig) "ignore_signal")
+
+(import-lambda-definition handle-signal-default (sig) "handle_signal_default")
     
 ;;; I am ashamed to say the 33 below is completely bogus.
 ;;; What we want is a value that is 1 + max interrupt value.

scsh/sighandlers1.c

@@ -68,10 +68,30 @@ s48_value do_default_sigaction(s48_value _signal)
   return S48_UNSPECIFIC;
 }
 
+s48_value ignore_signal(s48_value _signal)
+{
+  sig_t res = signal(s48_extract_fixnum(_signal), SIG_IGN);
+  if (res == SIG_ERR)
+    s48_raise_os_error_1(errno, _signal);
+  return S48_UNSPECIFIC;
+}
+
+s48_value handle_signal_default(s48_value _signal)
+{
+  sig_t res = signal(s48_extract_fixnum(_signal), SIG_DFL);
+  if (res == SIG_ERR)
+    s48_raise_os_error_1(errno, _signal);
+  return S48_UNSPECIFIC;
+}
+
+
 s48_value s48_init_sighandlers(void)
 {
     S48_EXPORT_FUNCTION(sig2interrupt);
     S48_EXPORT_FUNCTION(do_default_sigaction);
+    S48_EXPORT_FUNCTION(ignore_signal);
+    S48_EXPORT_FUNCTION(handle_signal_default);
 
     return S48_UNSPECIFIC;
 }
+