Rework the match approach to prefer uniq over name

Previously we would match for name first, then uniq. But the name
matches are less reliable than uniq matches so where we can match for
uniq we should prefer that.

This avoids the case where where a name that applies to multiple
devices takes precedence over a more precise uniq match.

libwacom/libwacom.c

@@ -611,8 +611,9 @@ libwacom_new_from_path(const WacomDeviceDatabase *db, const char *path, WacomFal
 	const WacomDevice *device;
 	WacomDevice *ret = NULL;
 	WacomIntegrationFlags integration_flags;
-	char *name, *match_name;
-	char *uniq, *match_uniq;
+	char *name, *uniq;
+	const char *used_match_name = NULL;
+	const char *used_match_uniq = NULL;
 	WacomMatch *match;
 
 	switch (fallback) {
@@ -637,20 +638,34 @@ libwacom_new_from_path(const WacomDeviceDatabase *db, const char *path, WacomFal
 	if (!get_device_info (path, &vendor_id, &product_id, &name, &uniq, &bus, &integration_flags, error))
 		return NULL;
 
-	match_name = name;
-	match_uniq = uniq;
-	device = libwacom_new (db, match_name, match_uniq, vendor_id, product_id, bus, error);
-	if (device == NULL) {
-		match_uniq = NULL;
+	/* Uniq (where it exists) is more reliable than the name which may be re-used
+	 * across tablets. So try to find a uniq+name match first, then uniq-only, then
+	 * name-only.
+	 */
+	struct match_approach {
+		const char *name;
+		const char *uniq;
+	} approaches[] = {
+		{ name, uniq },
+		{ NULL, uniq },
+		{ name, NULL },
+		{ NULL, NULL },
+	};
+	struct match_approach *approach = approaches;
+	while (true) {
+		const char *match_name = approach->name;
+		const char *match_uniq = approach->uniq;
 		device = libwacom_new (db, match_name, match_uniq, vendor_id, product_id, bus, error);
-		if (device == NULL) {
-			match_name = NULL;
-			device = libwacom_new (db, match_name, match_uniq, vendor_id, product_id, bus, error);
-			if (device == NULL) {
-				match_uniq = uniq;
-				device = libwacom_new (db, match_name, match_uniq, vendor_id, product_id, bus, error);
-			}
+		if (device) {
+			used_match_name = match_name;
+			used_match_uniq = match_uniq;
+			break;
 		}
+
+		if (approach->name == NULL && approach->uniq == NULL)
+			break;
+
+		approach++;
 	}
 
 	if (device == NULL) {
@@ -673,7 +688,7 @@ libwacom_new_from_path(const WacomDeviceDatabase *db, const char *path, WacomFal
 	}
 
 	/* for multiple-match devices, set to the one we requested */
-	match = libwacom_match_new(match_name, match_uniq, bus, vendor_id, product_id);
+	match = libwacom_match_new(used_match_name, used_match_uniq, bus, vendor_id, product_id);
 	libwacom_set_default_match(ret, match);
 	libwacom_match_unref(match);