Add storage provider open method

storage/storage.go

@@ -50,6 +50,10 @@ func (sp FileSystemStorageProvider) GetPath(bucketName string, objectName string
 	return filepath.Join(sp.wd, StorageFolderName, sp.basePath, bucketName, objectName)
 }
 
+func (sp FileSystemStorageProvider) OpenFile(bucketName string, objectName string) (*os.File, error) {
+	return os.Open(sp.GetPath(bucketName, objectName))
+}
+
 func GetFileSystemStorageProvider(basePath string, wd string) FileSystemStorageProvider {
 	if wd == "" {
 		wd, _ = os.Getwd()