Move syncpipe into separate package

This moves the sync pipe into a separate package to help the changes
when moving the API around.

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

namespaces/exec.go

@@ -12,6 +12,7 @@ import (
 	"github.com/docker/libcontainer/cgroups/fs"
 	"github.com/docker/libcontainer/cgroups/systemd"
 	"github.com/docker/libcontainer/network"
+	"github.com/docker/libcontainer/syncpipe"
 	"github.com/dotcloud/docker/pkg/system"
 )
 
@@ -28,7 +29,7 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 
 	// create a pipe so that we can syncronize with the namespaced process and
 	// pass the veth name to the child
-	syncPipe, err := NewSyncPipe()
+	syncPipe, err := syncpipe.NewSyncPipe()
 	if err != nil {
 		return -1, err
 	}
@@ -42,7 +43,7 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 		term.SetMaster(master)
 	}
 
-	command := createCommand(container, console, rootfs, dataPath, os.Args[0], syncPipe.child, args)
+	command := createCommand(container, console, rootfs, dataPath, os.Args[0], syncPipe.Child(), args)
 
 	if err := term.Attach(command); err != nil {
 		return -1, err
@@ -166,7 +167,7 @@ func SetupCgroups(container *libcontainer.Config, nspid int) (cgroups.ActiveCgro
 
 // InitializeNetworking creates the container's network stack outside of the namespace and moves
 // interfaces into the container's net namespaces if necessary
-func InitializeNetworking(container *libcontainer.Config, nspid int, pipe *SyncPipe, networkState *network.NetworkState) error {
+func InitializeNetworking(container *libcontainer.Config, nspid int, pipe *syncpipe.SyncPipe, networkState *network.NetworkState) error {
 	for _, config := range container.Networks {
 		strategy, err := network.GetStrategy(config.Type)
 		if err != nil {

namespaces/init.go

@@ -18,6 +18,7 @@ import (
 	"github.com/docker/libcontainer/network"
 	"github.com/docker/libcontainer/security/capabilities"
 	"github.com/docker/libcontainer/security/restrict"
+	"github.com/docker/libcontainer/syncpipe"
 	"github.com/docker/libcontainer/utils"
 	"github.com/dotcloud/docker/pkg/system"
 	"github.com/dotcloud/docker/pkg/user"
@@ -27,7 +28,7 @@ import (
 // Move this to libcontainer package.
 // Init is the init process that first runs inside a new namespace to setup mounts, users, networking,
 // and other options required for the new container.
-func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, syncPipe *SyncPipe, args []string) (err error) {
+func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, syncPipe *syncpipe.SyncPipe, args []string) (err error) {
 	defer func() {
 		if err != nil {
 			syncPipe.ReportChildError(err)

nsinit/init.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/codegangsta/cli"
 	"github.com/docker/libcontainer/namespaces"
+	"github.com/docker/libcontainer/syncpipe"
 )
 
 var (
@@ -37,7 +38,7 @@ func initAction(context *cli.Context) {
 		log.Fatal(err)
 	}
 
-	syncPipe, err := namespaces.NewSyncPipeFromFd(0, uintptr(pipeFd))
+	syncPipe, err := syncpipe.NewSyncPipeFromFd(0, uintptr(pipeFd))
 	if err != nil {
 		log.Fatalf("unable to create sync pipe: %s", err)
 	}

syncpipe/sync_pipe.go

@@ -1,4 +1,4 @@
-package namespaces
+package syncpipe
 
 import (
 	"encoding/json"

syncpipe/sync_pipe_linux.go

@@ -1,4 +1,4 @@
-package namespaces
+package syncpipe
 
 import (
 	"os"

syncpipe/sync_pipe_test.go

@@ -1,4 +1,4 @@
-package namespaces
+package syncpipe
 
 import (
 	"fmt"