ratbagd: ignore anything but event devices

We are only interested in evdev, so ignore anything but input-event
devices.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

src/ratbagd.c

@@ -58,7 +58,7 @@ static void ratbagd_process_device(struct ratbagd *ctx,
 	 */
 
 	name = udev_device_get_sysname(udevice);
-	if (!name)
+	if (!name || !startswith(name, "event"))
 		return;
 
 	device = ratbagd_find_device(ctx, name);

src/shared-macro.h

@@ -185,6 +185,25 @@ static inline bool streq_ptr(const char *a, const char *b)
 	return (a && b) ? streq(a, b) : (!a && !b);
 }
 
+/*
+ * startswith() - test prefix of a string
+ * @s: string to test
+ * @prefix: prefix to test for
+ *
+ * This returns a pointer to the first character in @s that follows @prefix. If
+ * @s does not start with @prefix, NULL is returned.
+ */
+static inline char *startswith(const char *s, const char *prefix)
+{
+	size_t l;
+
+	l = strlen(prefix);
+	if (strncmp(s, prefix, l) == 0)
+		return (char*) s + l;
+
+	return NULL;
+}
+
 /*
  * now() - returns current time in nano-seconds
  * @clock: clock to use