backlight: Avoid passing an invalid fd into close()
diff --git a/src/libbacklight.c b/src/libbacklight.c
index add89b2..98a20be 100644
--- a/src/libbacklight.c
+++ b/src/libbacklight.c
@@ -68,7 +68,8 @@
 	value = strtol(buffer, NULL, 10);
 	ret = value;
 out:
-	close(fd);
+	if (fd >= 0)
+		close(fd);
 	free(path);
 	return ret;
 }
@@ -124,10 +125,10 @@
 	ret = backlight_get_brightness(backlight);
 	backlight->brightness = ret;
 out:
-	if (buffer)
-		free(buffer);
+	free(buffer);
 	free(path);
-	close(fd);
+	if (fd >= 0)
+		close(fd);
 	return ret;
 }