@@ -382,6 +382,7 @@ type tarAppender struct {

 	// for hardlink mapping

 	SeenFiles  map[uint64]string

 	IDMappings *idtools.IDMappings

+	ChownOpts  *idtools.IDPair

 	// For packing and unpacking whiteout files in the

 	// non standard format. The whiteout files defined

@@ -390,12 +391,13 @@ type tarAppender struct {

 	WhiteoutConverter tarWhiteoutConverter

 }

-func newTarAppender(idMapping *idtools.IDMappings, writer io.Writer) *tarAppender {

+func newTarAppender(idMapping *idtools.IDMappings, writer io.Writer, chownOpts *idtools.IDPair) *tarAppender {

 	return &tarAppender{

 		SeenFiles:  make(map[uint64]string),

 		TarWriter:  tar.NewWriter(writer),

 		Buffer:     pools.BufioWriter32KPool.Get(nil),

 		IDMappings: idMapping,

+		ChownOpts:  chownOpts,

 	}

 }

@@ -470,6 +472,12 @@ func (ta *tarAppender) addTarFile(path, name string) error {

 		}

 	}

+	// explicitly override with ChownOpts

+	if ta.ChownOpts != nil {

+		hdr.Uid = ta.ChownOpts.UID

+		hdr.Gid = ta.ChownOpts.GID

+	}

+

 	if ta.WhiteoutConverter != nil {

 		wo, err := ta.WhiteoutConverter.ConvertWrite(hdr, path, fi)

 		if err != nil {

@@ -692,6 +700,7 @@ func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error)

 		ta := newTarAppender(

 			idtools.NewIDMappingsFromMaps(options.UIDMaps, options.GIDMaps),

 			compressWriter,

+			options.ChownOpts,

 		)

 		ta.WhiteoutConverter = getWhiteoutConverter(options.WhiteoutFormat)

@@ -14,6 +14,7 @@ import (

 	"testing"

 	"time"

+	"github.com/docker/docker/pkg/idtools"

 	"github.com/stretchr/testify/assert"

 	"github.com/stretchr/testify/require"

 )

@@ -724,6 +725,57 @@ func TestTarUntar(t *testing.T) {

 	}

 }

+func TestTarWithOptionsChownOptsAlwaysOverridesIdPair(t *testing.T) {

+	origin, err := ioutil.TempDir("", "docker-test-tar-chown-opt")

+	require.NoError(t, err)

+

+	defer os.RemoveAll(origin)

+	filePath := filepath.Join(origin, "1")

+	err = ioutil.WriteFile(filePath, []byte("hello world"), 0700)

+	require.NoError(t, err)

+

+	idMaps := []idtools.IDMap{

+		0: {

+			ContainerID: 0,

+			HostID:      0,

+			Size:        65536,

+		},

+		1: {

+			ContainerID: 0,

+			HostID:      100000,

+			Size:        65536,

+		},

+	}

+

+	cases := []struct {

+		opts        *TarOptions

+		expectedUID int

+		expectedGID int

+	}{

+		{&TarOptions{ChownOpts: &idtools.IDPair{UID: 1337, GID: 42}}, 1337, 42},

+		{&TarOptions{ChownOpts: &idtools.IDPair{UID: 100001, GID: 100001}, UIDMaps: idMaps, GIDMaps: idMaps}, 100001, 100001},

+		{&TarOptions{ChownOpts: &idtools.IDPair{UID: 0, GID: 0}, NoLchown: false}, 0, 0},

+		{&TarOptions{ChownOpts: &idtools.IDPair{UID: 1, GID: 1}, NoLchown: true}, 1, 1},

+		{&TarOptions{ChownOpts: &idtools.IDPair{UID: 1000, GID: 1000}, NoLchown: true}, 1000, 1000},

+	}

+	for _, testCase := range cases {

+		reader, err := TarWithOptions(filePath, testCase.opts)

+		require.NoError(t, err)

+		tr := tar.NewReader(reader)

+		defer reader.Close()

+		for {

+			hdr, err := tr.Next()

+			if err == io.EOF {

+				// end of tar archive

+				break

+			}

+			require.NoError(t, err)

+			assert.Equal(t, hdr.Uid, testCase.expectedUID, "Uid equals expected value")

+			assert.Equal(t, hdr.Gid, testCase.expectedGID, "Gid equals expected value")

+		}

+	}

+}

+

 func TestTarWithOptions(t *testing.T) {

 	// TODO Windows: Figure out how to fix this test.

 	if runtime.GOOS == "windows" {

@@ -394,7 +394,7 @@ func ChangesSize(newDir string, changes []Change) int64 {

 func ExportChanges(dir string, changes []Change, uidMaps, gidMaps []idtools.IDMap) (io.ReadCloser, error) {

 	reader, writer := io.Pipe()

 	go func() {

-		ta := newTarAppender(idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), writer)

+		ta := newTarAppender(idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), writer, nil)

 		// this buffer is needed for the duration of this piped stream

 		defer pools.BufioWriter32KPool.Put(ta.Buffer)