[fileutil] use 0755 as default filemode to create dir

Author: hezhizhen

internal/fileutil/dir.go

@@ -27,11 +27,13 @@ func CopyAll(src, dst string) error {
 }
 
 func ClearDir(dir string) error {
+	// if the dir doesn't exist, use default filemode 0755 to create it
+	// if the dir exists, use its own filemode to re-create it
+	var mode os.FileMode = 0755
 	f, err := os.Stat(dir)
-	if err != nil {
-		return errors.WithStack(err)
+	if err == nil {
+		mode = f.Mode()
 	}
-	mode := f.Mode()
 
 	if err := os.RemoveAll(dir); err != nil {
 		return errors.WithStack(err)