clash api: download clash-dashboard if external-ui directory is empty

constant/path.go

@@ -12,6 +12,7 @@ const dirName = "sing-box"
 
 var (
 	basePath      string
+	tempPath      string
 	resourcePaths []string
 )
 
@@ -22,10 +23,21 @@ func BasePath(name string) string {
 	return filepath.Join(basePath, name)
 }
 
+func CreateTemp(pattern string) (*os.File, error) {
+	if tempPath == "" {
+		tempPath = os.TempDir()
+	}
+	return os.CreateTemp(tempPath, pattern)
+}
+
 func SetBasePath(path string) {
 	basePath = path
 }
 
+func SetTempPath(path string) {
+	tempPath = path
+}
+
 func FindPath(name string) (string, bool) {
 	name = os.ExpandEnv(name)
 	if rw.FileExists(name) {