func tarFromFilesInGraph(graph graphdriver.Driver, graphID, parentID string, files ...FileApplier) ([]byte, error) {
t, err := tarFromFiles(files...)
if err != nil {
return nil, err
}
if err := graph.Create(graphID, parentID, ""); err != nil {
return nil, err
}
if _, err := graph.ApplyDiff(graphID, parentID, archive.Reader(bytes.NewReader(t))); err != nil {
return nil, err
}
ar, err := graph.Diff(graphID, parentID)
if err != nil {
return nil, err
}
defer ar.Close()
return ioutil.ReadAll(ar)
}