Übung 5

Assets/Betriebssysteme_uebung/u6-a2-anlage/daemon.c

@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <signal.h>
+
+#include "helpers.h"
+
+void got_signal(int s) {
+	/*
+	 * For demonstration purposes only!
+	 *
+	 * In real-world applications avoid the execution of complex
+	 * tasks in signal handlers, this cries for race conditions and
+	 * exploits.
+	 *
+	 * https://web.archive.org/web/20070204064240/http://www.bindview.com:80/
+	 % Services/Razor/Papers/2001/signals.cfm
+	 */
+
+	static int count = 2;
+
+	fprintf(stderr, "Caught Ctrl-C, press %i more time%s to really"
+		" quit.\n", count, count == 1 ? "" : "s");
+
+	if (count-- > 1) {
+		/* Catch subsequent SIGINTs */
+		signal(SIGINT, got_signal);
+	}
+	else {
+		/* Don't catch SIGINT anymore */
+		signal(SIGINT, SIG_DFL);
+	}
+}
+
+int main(void) {
+	/*
+	 * Initialization...
+	 */
+	void load_cfg(int x) // Wrapper um die inkompatibilität durch die fehlerhafte methodendeklaration zu beheben
+	{
+		load_config();
+	}
+	load_config();
+	signal(SIGHUP, load_cfg); 
+	signal(SIGINT, got_signal);
+	signal(SIGKILL, SIG_IGN); // Unaufhaltsam, da SIGKILL sich ja eben genau nicht um das Programm kümmern soll, sondern einfach immer töten soll
+	signal(SIGTERM, SIG_IGN); // Aufhaltbar
+	
+	/*
+	 * Do some work.
+	 */
+
+	main_loop();
+
+	return 0;
+}