add CTRL+C handler

~/C/libserialport/listen.c

@@ -2,9 +2,13 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
+#include <signal.h>
 
 /* Helper function for error handling. */
 int check(enum sp_return result);
+void handle_sigint(int sig);
+
+bool INTERRUPT = false;
 
 int main(int argc, char **argv) {
   struct sp_port *serial_port;
@@ -59,9 +63,11 @@ int main(int argc, char **argv) {
   check(sp_set_flowcontrol(serial_port, SP_FLOWCONTROL_NONE));
   puts("Connected.");
 
+  signal(SIGINT, handle_sigint);
+
   /* Reading lines from serial port. */
   bool reading = true;
-  while (reading) {
+  while (reading && !INTERRUPT) {
     int pos = 0;
 
     /* Character-by-character reading. */
@@ -119,3 +125,5 @@ int check(enum sp_return result) {
     return result;
   }
 }
+
+void handle_sigint(int sig) { INTERRUPT = true; }