u2_bt: add watchdog

u2_bt.c

@@ -1,4 +1,4 @@
-/* Copyright 2019 King Kévin <kingkevin@cuvoodoo.info>
+/* Copyright 2019-2020 King Kévin <kingkevin@cuvoodoo.info>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -31,6 +31,7 @@
 #include <stdarg.h>
 #include <unistd.h>
 #include <assert.h>
+#include <signal.h>
 #include <dbus/dbus.h>
 #include <sys/select.h>
 #include <sys/time.h>
@@ -72,6 +73,15 @@ static void die(const char* format, ...)
 	exit(1);
 }
 
+/* watchdog called after alarm timeout
+ * @param[in] sig alarm signal
+ */
+static void watchdog(int sig)
+{
+	(void)sig; // argument not used
+	die("exiting due to inactivity\n");
+}
+
 /* get all D-Bus object paths with matching interface
  * @param[in] connection D-Bus connection
  * @param[in] bus_name bus to get objects from
@@ -411,6 +421,9 @@ int main(int argc, char* argv[])
 		}
 	}
 
+	signal(SIGALRM, watchdog); // setup watchdog
+	alarm(30); // start watchdog (in case connecting to the U2 gets stuck)
+
 	// UDP socket to send data to influxdb
 	int influxdb_fd = 0;
 	struct addrinfo* res = 0;
@@ -794,6 +807,7 @@ int main(int argc, char* argv[])
 					printf_debug("energy: %.04f Wh\n", fvalue);
 					printf_debug("group: %u\n", packet[18] + 1);
 				} else if (0xfe == packet[0] && packet[1] < 6 && packet[18] < 6 && 0x00 == packet[19]) { // measurement packet (use group limit and last byte to somehow detect transmission errors)
+					alarm(10); // restart watchdog
 					u2_values.messages |= (1 << packet[1]);
 					if (u2_values.group != (packet[18] + 1)) { // new group
 						u2_values.messages = 0; // remember not all message has been received