@@ -7,6 +7,7 @@ import (

 	"io/ioutil"

 	"os"

 	"path/filepath"

+	"reflect"

 	"github.com/Sirupsen/logrus"

 	"github.com/docker/docker/image"

@@ -58,6 +59,8 @@ func (l *tarexporter) Load(inTar io.ReadCloser, outStream io.Writer, quiet bool)

 		return err

 	}

+	var parentLinks []parentLink

+

 	for _, m := range manifest {

 		configPath, err := safePath(tmpDir, m.Config)

 		if err != nil {

@@ -117,11 +120,35 @@ func (l *tarexporter) Load(inTar io.ReadCloser, outStream io.Writer, quiet bool)

 			l.setLoadedTag(ref, imgID, outStream)

 		}

+		parentLinks = append(parentLinks, parentLink{imgID, m.Parent})

+	}

+

+	for _, p := range validatedParentLinks(parentLinks) {

+		if p.parentID != "" {

+			if err := l.setParentID(p.id, p.parentID); err != nil {

+				return err

+			}

+		}

 	}

 	return nil

 }

+func (l *tarexporter) setParentID(id, parentID image.ID) error {

+	img, err := l.is.Get(id)

+	if err != nil {

+		return err

+	}

+	parent, err := l.is.Get(parentID)

+	if err != nil {

+		return err

+	}

+	if !checkValidParent(img, parent) {

+		return fmt.Errorf("image %v is not a valid parent for %v", parent.ID, img.ID)

+	}

+	return l.is.SetParent(id, parentID)

+}

+

 func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, progressOutput progress.Output) (layer.Layer, error) {

 	rawTar, err := os.Open(filename)

 	if err != nil {

@@ -309,3 +336,36 @@ func (l *tarexporter) legacyLoadImage(oldID, sourceDir string, loadedMap map[str

 func safePath(base, path string) (string, error) {

 	return symlink.FollowSymlinkInScope(filepath.Join(base, path), base)

 }

+

+type parentLink struct {

+	id, parentID image.ID

+}

+

+func validatedParentLinks(pl []parentLink) (ret []parentLink) {

+mainloop:

+	for i, p := range pl {

+		ret = append(ret, p)

+		for _, p2 := range pl {

+			if p2.id == p.parentID && p2.id != p.id {

+				continue mainloop

+			}

+		}

+		ret[i].parentID = ""

+	}

+	return

+}

+

+func checkValidParent(img, parent *image.Image) bool {

+	if len(img.History) == 0 && len(parent.History) == 0 {

+		return true // having history is not mandatory

+	}

+	if len(img.History)-len(parent.History) != 1 {

+		return false

+	}

+	for i, h := range parent.History {

+		if !reflect.DeepEqual(h, img.History[i]) {

+			return false

+		}

+	}

+	return true

+}

@@ -128,6 +128,7 @@ func (s *saveSession) save(outStream io.Writer) error {

 	reposLegacy := make(map[string]map[string]string)

 	var manifest []manifestItem

+	var parentLinks []parentLink

 	for id, imageDescr := range s.images {

 		if err = s.saveImage(id); err != nil {

@@ -154,6 +155,15 @@ func (s *saveSession) save(outStream io.Writer) error {

 			RepoTags: repoTags,

 			Layers:   layers,

 		})

+

+		parentID, _ := s.is.GetParent(id)

+		parentLinks = append(parentLinks, parentLink{id, parentID})

+	}

+

+	for i, p := range validatedParentLinks(parentLinks) {

+		if p.parentID != "" {

+			manifest[i].Parent = p.parentID

+		}

 	}

 	if len(reposLegacy) > 0 {

@@ -18,6 +18,7 @@ type manifestItem struct {

 	Config   string

 	RepoTags []string

 	Layers   []string

+	Parent   image.ID `json:",omitempty"`

 }

 type tarexporter struct {

@@ -311,3 +311,42 @@ func (s *DockerSuite) TestLoadZeroSizeLayer(c *check.C) {

 	dockerCmd(c, "load", "-i", "fixtures/load/emptyLayer.tar")

 }

+

+func (s *DockerSuite) TestSaveLoadParents(c *check.C) {

+	testRequires(c, DaemonIsLinux)

+

+	makeImage := func(from string, addfile string) string {

+		var (

+			out string

+		)

+		out, _ = dockerCmd(c, "run", "-d", from, "touch", addfile)

+		cleanedContainerID := strings.TrimSpace(out)

+

+		out, _ = dockerCmd(c, "commit", cleanedContainerID)

+		imageID := strings.TrimSpace(out)

+

+		dockerCmd(c, "rm", cleanedContainerID)

+		return imageID

+	}

+

+	idFoo := makeImage("busybox", "foo")

+	idBar := makeImage(idFoo, "bar")

+

+	tmpDir, err := ioutil.TempDir("", "save-load-parents")

+	c.Assert(err, checker.IsNil)

+	defer os.RemoveAll(tmpDir)

+

+	c.Log("tmpdir", tmpDir)

+

+	outfile := filepath.Join(tmpDir, "out.tar")

+

+	dockerCmd(c, "save", "-o", outfile, idBar, idFoo)

+	dockerCmd(c, "rmi", idBar)

+	dockerCmd(c, "load", "-i", outfile)

+

+	inspectOut := inspectField(c, idBar, "Parent")

+	c.Assert(inspectOut, checker.Equals, idFoo)

+

+	inspectOut = inspectField(c, idFoo, "Parent")

+	c.Assert(inspectOut, checker.Equals, "")

+}