@@ -112,7 +112,7 @@ func (graph *Graph) Create(layerData Archive, container *Container, comment, aut

 		img.Container = container.Id

 		img.ContainerConfig = *container.Config

 	}

-	if err := graph.Register(layerData, img); err != nil {

+	if err := graph.Register(layerData, true, img); err != nil {

 		return nil, err

 	}

 	go img.Checksum()

@@ -121,7 +121,7 @@ func (graph *Graph) Create(layerData Archive, container *Container, comment, aut

 // Register imports a pre-existing image into the graph.

 // FIXME: pass img as first argument

-func (graph *Graph) Register(layerData Archive, img *Image) error {

+func (graph *Graph) Register(layerData Archive, store bool, img *Image) error {

 	if err := ValidateId(img.Id); err != nil {

 		return err

 	}

@@ -134,7 +134,7 @@ func (graph *Graph) Register(layerData Archive, img *Image) error {

 	if err != nil {

 		return fmt.Errorf("Mktemp failed: %s", err)

 	}

-	if err := StoreImage(img, layerData, tmp); err != nil {

+	if err := StoreImage(img, layerData, tmp, store); err != nil {

 		return err

 	}

 	// Commit

@@ -56,7 +56,7 @@ func LoadImage(root string) (*Image, error) {

 	return img, nil

 }

-func StoreImage(img *Image, layerData Archive, root string) error {

+func StoreImage(img *Image, layerData Archive, root string, store bool) error {

 	// Check that root doesn't already exist

 	if _, err := os.Stat(root); err == nil {

 		return fmt.Errorf("Image %s already exists", img.Id)

@@ -68,6 +68,28 @@ func StoreImage(img *Image, layerData Archive, root string) error {

 	if err := os.MkdirAll(layer, 0700); err != nil {

 		return err

 	}

+

+	if store {

+		layerArchive := layerArchivePath(root)

+		file, err := os.OpenFile(layerArchive, os.O_WRONLY|os.O_CREATE, 0600)

+		if err != nil {

+			return err

+		}

+		// FIXME: Retrieve the image layer size from here?

+		if _, err := io.Copy(file, layerData); err != nil {

+			return err

+		}

+		// FIXME: Don't close/open, read/write instead of Copy

+		file.Close()

+

+		file, err = os.Open(layerArchive)

+		if err != nil {

+			return err

+		}

+		defer file.Close()

+		layerData = file

+	}

+

 	if err := Untar(layerData, layer); err != nil {

 		return err

 	}

@@ -86,6 +108,10 @@ func layerPath(root string) string {

 	return path.Join(root, "layer")

 }

+func layerArchivePath(root string) string {

+	return path.Join(root, "layer.tar.xz")

+}

+

 func jsonPath(root string) string {

 	return path.Join(root, "json")

 }

@@ -290,9 +316,20 @@ func (img *Image) Checksum() (string, error) {

 		return "", err

 	}

-	layerData, err := Tar(layer, Xz)

-	if err != nil {

-		return "", err

+	var layerData io.Reader

+

+	if file, err := os.Open(layerArchivePath(root)); err != nil {

+		if os.IsNotExist(err) {

+			layerData, err = Tar(layer, Xz)

+			if err != nil {

+				return "", err

+			}

+		} else {

+			return "", err

+		}

+	} else {

+		defer file.Close()

+		layerData = file

 	}

 	h := sha256.New()

@@ -259,7 +259,7 @@ func (graph *Graph) PullImage(stdout io.Writer, imgId, registry string, token []

 				// FIXME: Keep goging in case of error?

 				return err

 			}

-			if err = graph.Register(layer, img); err != nil {

+			if err = graph.Register(layer, false, img); err != nil {

 				return err

 			}

 		}