desktop: exit if loop() doesn't run for 5 seconds

this should stop runaway processes

libraries/Desktop/support/main.cpp

@@ -5,6 +5,7 @@
 #include <sched.h>
 #include <wiring.h>
 #include <getopt.h>
+#include <signal.h>
 #include "desktop.h"
 
 void setup(void);
@@ -20,6 +21,12 @@ static void usage(void)
 	printf("\t-w          wipe eeprom and dataflash\n");
 }
 
+void sig_alarm(int sig)
+{
+	printf("alarm signal in desktop emulation - loop not running\n");
+	exit(1);
+}
+
 int main(int argc, char * const argv[])
 {
 	int opt;
@@ -43,6 +50,9 @@ int main(int argc, char * const argv[])
 		}
 	}
 
+	signal(SIGALRM, sig_alarm);
+	alarm(5);
+
 	// run main setup() function from sketch
 	setup();
 
@@ -51,6 +61,8 @@ int main(int argc, char * const argv[])
 		fd_set fds;
 		int fd_high = 0;
 
+		alarm(5);
+
 		FD_ZERO(&fds);
 		FD_SET(0, &fds);
 		loop();