Fix some UB in signal handling

can.c

@@ -101,7 +101,6 @@ static int can_send_break(struct ios_ops *ios)
 static void can_exit(struct ios_ops *ios)
 {
 	close(ios->fd);
-	free(ios);
 }
 
 struct ios_ops *can_init(char *interface_id)

commands.c

@@ -149,7 +149,9 @@ static int cmd_break(int argc, char *argv[])
 
 static int cmd_quit(int argc, char *argv[])
 {
+	fflush(NULL);
 	microcom_exit(0);
+	exit(0);
 	return 0;
 }
 

microcom.c

@@ -67,12 +67,13 @@ void restore_terminal(void)
 
 void microcom_exit(int signal)
 {
-	printf("exiting\n");
+	write(1, "exiting\n", 8);
 
 	ios->exit(ios);
 	tcsetattr(STDIN_FILENO, TCSANOW, &sots);
 
-	exit(0);
+	if (signal)
+		_Exit(0);
 }
 
 /********************************************************************
@@ -122,7 +123,7 @@ char escape_char = DEFAULT_ESCAPE_CHAR;
 
 int main(int argc, char *argv[])
 {
-	struct sigaction sact;  /* used to initialize the signal handler */
+	struct sigaction sact = {0};  /* used to initialize the signal handler */
 	int opt, ret;
 	char *hostport = NULL;
 	int telnet = 0, can = 0;

serial.c

@@ -225,7 +225,6 @@ static void serial_exit(struct ios_ops *ios)
 {
 	tcsetattr(ios->fd, TCSANOW, &pots);
 	close(ios->fd);
-	free(ios);
 }
 
 struct ios_ops * serial_init(char *device)

telnet.c

@@ -523,7 +523,6 @@ static int telnet_send_break(struct ios_ops *ios)
 static void telnet_exit(struct ios_ops *ios)
 {
 	close(ios->fd);
-	free(ios);
 }
 
 struct ios_ops *telnet_init(char *hostport)