@@ -262,7 +262,7 @@ Setting up a dev environment

 Instructions that have been verified to work on Ubuntu 12.10,

 ```bash

-sudo apt-get -y install lxc wget bsdtar curl golang git

+sudo apt-get -y install lxc curl xz-utils golang git

 export GOPATH=~/go/

 export PATH=$GOPATH/bin:$PATH

@@ -1,8 +1,10 @@

 package docker

 import (

+	"bufio"

 	"errors"

 	"fmt"

+	"github.com/dotcloud/docker/utils"

 	"io"

 	"io/ioutil"

 	"os"

@@ -20,6 +22,37 @@ const (

 	Xz

 )

+func DetectCompression(source []byte) Compression {

+	for _, c := range source[:10] {

+		utils.Debugf("%x", c)

+	}

+

+	sourceLen := len(source)

+	for compression, m := range map[Compression][]byte{

+		Bzip2: {0x42, 0x5A, 0x68},

+		Gzip:  {0x1F, 0x8B, 0x08},

+		Xz:    {0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00},

+	} {

+		fail := false

+		if len(m) > sourceLen {

+			utils.Debugf("Len too short")

+			continue

+		}

+		i := 0

+		for _, b := range m {

+			if b != source[i] {

+				fail = true

+				break

+			}

+			i++

+		}

+		if !fail {

+			return compression

+		}

+	}

+	return Uncompressed

+}

+

 func (compression *Compression) Flag() string {

 	switch *compression {

 	case Bzip2:

@@ -47,14 +80,23 @@ func (compression *Compression) Extension() string {

 }

 func Tar(path string, compression Compression) (io.Reader, error) {

-	cmd := exec.Command("bsdtar", "-f", "-", "-C", path, "-c"+compression.Flag(), ".")

-	return CmdStream(cmd)

+	return CmdStream(exec.Command("tar", "-f", "-", "-C", path, "-c"+compression.Flag(), "."))

 }

 // FIXME: specify behavior when target path exists vs. doesn't exist.

 func Untar(archive io.Reader, path string) error {

-	cmd := exec.Command("bsdtar", "-f", "-", "-C", path, "-x")

-	cmd.Stdin = archive

+

+	bufferedArchive := bufio.NewReaderSize(archive, 10)

+	buf, err := bufferedArchive.Peek(10)

+	if err != nil {

+		return err

+	}

+	compression := DetectCompression(buf)

+

+	utils.Debugf("Archive compression detected: %s", compression.Extension())

+

+	cmd := exec.Command("tar", "-f", "-", "-C", path, "-x"+compression.Flag())

+	cmd.Stdin = bufferedArchive

 	// Hardcode locale environment for predictable outcome regardless of host configuration.

 	//   (see https://github.com/dotcloud/docker/issues/355)

 	cmd.Env = []string{"LANG=en_US.utf-8", "LC_ALL=en_US.utf-8"}

@@ -1,10 +1,13 @@

 package docker

 import (

+	"bytes"

+	"fmt"

 	"io"

 	"io/ioutil"

 	"os"

 	"os/exec"

+	"path"

 	"testing"

 	"time"

 )

@@ -58,20 +61,58 @@ func TestCmdStreamGood(t *testing.T) {

 	}

 }

-func TestTarUntar(t *testing.T) {

-	archive, err := Tar(".", Uncompressed)

+func tarUntar(t *testing.T, origin string, compression Compression) error {

+	archive, err := Tar(origin, compression)

 	if err != nil {

 		t.Fatal(err)

 	}

+

+	buf := make([]byte, 10)

+	if _, err := archive.Read(buf); err != nil {

+		return err

+	}

+	archive = io.MultiReader(bytes.NewReader(buf), archive)

+

+	detectedCompression := DetectCompression(buf)

+	if detectedCompression.Extension() != compression.Extension() {

+		return fmt.Errorf("Wrong compression detected. Actual compression: %s, found %s", compression.Extension(), detectedCompression.Extension())

+	}

+

 	tmp, err := ioutil.TempDir("", "docker-test-untar")

 	if err != nil {

-		t.Fatal(err)

+		return err

 	}

 	defer os.RemoveAll(tmp)

 	if err := Untar(archive, tmp); err != nil {

-		t.Fatal(err)

+		return err

 	}

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

-		t.Fatalf("Error stating %s: %s", tmp, err.Error())

+		return err

+	}

+	return nil

+}

+

+func TestTarUntar(t *testing.T) {

+	origin, err := ioutil.TempDir("", "docker-test-untar-origin")

+	if err != nil {

+		t.Fatal(err)

+	}

+	defer os.RemoveAll(origin)

+	if err := ioutil.WriteFile(path.Join(origin, "1"), []byte("hello world"), 0700); err != nil {

+		t.Fatal(err)

+	}

+	if err := ioutil.WriteFile(path.Join(origin, "2"), []byte("welcome!"), 0700); err != nil {

+		t.Fatal(err)

+	}

+

+	for _, c := range []Compression{

+		Uncompressed,

+		Gzip,

+		Bzip2,

+		Xz,

+	} {

+		if err := tarUntar(t, origin, c); err != nil {

+			t.Fatalf("Error tar/untar for compression %s: %s", c.Extension(), err)

+		}

 	}

 }

@@ -8,7 +8,7 @@

 echo "Ensuring basic dependencies are installed..."

 apt-get -qq update

-apt-get -qq install lxc wget bsdtar

+apt-get -qq install lxc wget

 echo "Looking in /proc/filesystems to see if we have AUFS support..."

 if grep -q aufs /proc/filesystems

@@ -33,7 +33,7 @@ Installation

     sudo apt-get install python-software-properties

     sudo add-apt-repository ppa:gophers/go

     sudo apt-get update

-    sudo apt-get -y install lxc wget bsdtar curl golang-stable git aufs-tools

+    sudo apt-get -y install lxc xz-utils curl golang-stable git aufs-tools

     export GOPATH=~/go/

     export PATH=$GOPATH/bin:$PATH

@@ -30,8 +30,7 @@ Dependencies:

 * 3.8 Kernel (read more about :ref:`kernel`)

 * AUFS filesystem support

 * lxc

-* bsdtar

-

+* xz-utils

 Get the docker binary:

 ----------------------

@@ -192,11 +192,19 @@ func TestDelete(t *testing.T) {

 	}

 	assertNImages(graph, t, 0)

+	archive, err = fakeTar()

+	if err != nil {

+		t.Fatal(err)

+	}

 	// Test 2 create (same name) / 1 delete

 	img1, err := graph.Create(archive, nil, "Testing", "", nil)

 	if err != nil {

 		t.Fatal(err)

 	}

+	archive, err = fakeTar()

+	if err != nil {

+		t.Fatal(err)

+	}

 	if _, err = graph.Create(archive, nil, "Testing", "", nil); err != nil {

 		t.Fatal(err)

 	}

@@ -212,6 +220,10 @@ func TestDelete(t *testing.T) {

 	}

 	assertNImages(graph, t, 1)

+	archive, err = fakeTar()

+	if err != nil {

+		t.Fatal(err)

+	}

 	// Test delete twice (pull -> rm -> pull -> rm)

 	if err := graph.Register(archive, false, img1); err != nil {

 		t.Fatal(err)

@@ -22,7 +22,7 @@ Vagrant::Config.run do |config|

   pkg_cmd = "touch #{DOCKER_PATH}; "

   # Install docker dependencies

   pkg_cmd << "export DEBIAN_FRONTEND=noninteractive; apt-get -qq update; " \

-    "apt-get install -q -y lxc bsdtar git aufs-tools golang make linux-image-extra-3.8.0-19-generic; " \

+    "apt-get install -q -y lxc git aufs-tools golang make linux-image-extra-3.8.0-19-generic; " \

     "chown -R #{USER}.#{USER} #{GOPATH}; " \

     "install -m 0664 #{CFG_PATH}/bash_profile /home/#{USER}/.bash_profile"

   config.vm.provision :shell, :inline => pkg_cmd

@@ -30,7 +30,7 @@ Vagrant::Config.run do |config|

     # Install docker dependencies

     pkg_cmd << "apt-get install -q -y python-software-properties; " \

       "add-apt-repository -y ppa:gophers/go/ubuntu; apt-get update -qq; " \

-      "DEBIAN_FRONTEND=noninteractive apt-get install -q -y lxc bsdtar git golang-stable aufs-tools make; "

+      "DEBIAN_FRONTEND=noninteractive apt-get install -q -y lxc git golang-stable aufs-tools make; "

     # Activate new kernel

     pkg_cmd << "shutdown -r +1; "

     config.vm.provision :shell, :inline => pkg_cmd