code: def _loc_to_file_path(self, path, environ=None):
          
          root_path = self.root_folder_path
          assert root_path is not None
          assert compat.is_native(root_path)
          assert compat.is_native(path)
  
          path_parts = path.strip("/").split("/")
          file_path = os.path.abspath(os.path.join(root_path, *path_parts))
          if not file_path.startswith(root_path):
              raise RuntimeError(
                  "Security exception: tried to access file outside root: {}".format(
                      file_path
                  )
              )
  
          # Convert to unicode
          file_path = util.to_unicode_safe(file_path)
          return file_path
docs: Convert resource path to a unicode absolute file path.
          Optional environ argument may be useful e.g. in relation to per-user
          sub-folder chrooting inside root_folder_path.