Update docker with syncpipe changes

We removed the syncpipe package and replaced it with specific calls to
create a new *os.File from a specified fd passed to the process.  This
reduced code and an extra object to manage the container's init
lifecycle.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

daemon/execdriver/native/init.go

@@ -13,7 +13,6 @@ import (
 	"github.com/docker/docker/pkg/reexec"
 	"github.com/docker/libcontainer"
 	"github.com/docker/libcontainer/namespaces"
-	"github.com/docker/libcontainer/syncpipe"
 )
 
 func init() {
@@ -48,12 +47,7 @@ func initializer() {
 		writeError(err)
 	}
 
-	syncPipe, err := syncpipe.NewSyncPipeFromFd(0, uintptr(*pipe))
-	if err != nil {
-		writeError(err)
-	}
-
-	if err := namespaces.Init(container, rootfs, *console, syncPipe, flag.Args()); err != nil {
+	if err := namespaces.Init(container, rootfs, *console, os.NewFile(uintptr(*pipe), "child"), flag.Args()); err != nil {
 		writeError(err)
 	}
 

daemon/execdriver/native/utils.go

@@ -3,10 +3,10 @@
 package native
 
 import (
+	"encoding/json"
 	"os"
 
 	"github.com/docker/libcontainer"
-	"github.com/docker/libcontainer/syncpipe"
 )
 
 func findUserArgs() []string {
@@ -21,15 +21,9 @@ func findUserArgs() []string {
 // loadConfigFromFd loads a container's config from the sync pipe that is provided by
 // fd 3 when running a process
 func loadConfigFromFd() (*libcontainer.Config, error) {
-	syncPipe, err := syncpipe.NewSyncPipeFromFd(0, 3)
-	if err != nil {
-		return nil, err
-	}
-
 	var config *libcontainer.Config
-	if err := syncPipe.ReadFromParent(&config); err != nil {
+	if err := json.NewDecoder(os.NewFile(3, "child")).Decode(&config); err != nil {
 		return nil, err
 	}
-
 	return config, nil
 }