Glob paths and return StatEntry objects.

def _ProcessFileSource(self, source):
    """Glob paths and return StatEntry objects."""

    if source.path_type != rdf_paths.PathSpec.PathType.OS:
      raise ValueError("Only supported path type is OS.")

    paths = artifact_utils.InterpolateListKbAttributes(
        source.base_source.attributes["paths"], self.knowledge_base,
        self.ignore_interpolation_errors)

    file_finder_action = rdf_file_finder.FileFinderAction.Stat()
    request = rdf_file_finder.FileFinderArgs(
        paths=paths, pathtype=source.path_type, action=file_finder_action)
    action = file_finder.FileFinderOSFromClient

    yield action, request