? external/mit/ctwm/dist/ChangeLog
Index: external/mit/ctwm/dist/signals.c
===================================================================
RCS file: /cvsroot/xsrc/external/mit/ctwm/dist/signals.c,v
retrieving revision 1.1.1.1
diff -p -u -r1.1.1.1 signals.c
--- external/mit/ctwm/dist/signals.c	5 Jul 2023 07:36:07 -0000	1.1.1.1
+++ external/mit/ctwm/dist/signals.c	12 Aug 2023 11:39:39 -0000
@@ -26,6 +26,14 @@ static bool sig_shutdown = false;
 // needs to trigger an action.
 bool SignalFlag = false;
 
+#ifdef __NetBSD__
+SIGNAL_T ChildExit(int signum)
+{
+	int Errno = errno;
+	waitpid(-1, NULL, WNOHANG);  /* reap dead child, ignore status */
+	errno = Errno;               /* restore errno for interrupted sys calls */
+}
+#endif
 
 /**
  * Setup signal handlers (run during startup)
@@ -46,9 +54,18 @@ setup_signal_handlers(void)
 	// die...
 	signal(SIGALRM, SIG_IGN);
 
+#ifdef __NetBSD__
+	/* Setting SIGCHLD to SIG_IGN detaches children from the parent
+	 * immediately, so it need not be waited for.
+	 * In fact, you cannot wait for it, so a function like system()
+	 * breaks.
+	 */
+	signal(SIGCHLD, ChildExit);
+#else
 	// This should be set by default, but just in case; explicitly don't
 	// leave zombies.
 	signal(SIGCHLD, SIG_IGN);
+#endif
 
 	return;
 }