tools:iio:iio_event_monitor: add error handling

Add error handling to calls which can indicate a major problem by
returning an error code.
Signed-off-by: NHartmut Knaack <knaack.h@gmx.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

tools/iio/iio_event_monitor.c

@@ -286,7 +286,10 @@ int main(int argc, char **argv)
 		goto error_free_chrdev_name;
 	}
 
-	close(fd);
+	if (close(fd) == -1)  {
+		ret = -errno;
+		goto error_free_chrdev_name;
+	}
 
 	while (true) {
 		ret = read(event_fd, &event, sizeof(event));
@@ -304,7 +307,9 @@ int main(int argc, char **argv)
 		print_event(&event);
 	}
 
-	close(event_fd);
+	if (close(event_fd) == -1)
+		perror("Failed to close event file");
+
 error_free_chrdev_name:
 	free(chrdev_name);
 error_ret: