Make syncpipe transport generic data

Signed-off-by: Michael Crosby <michael@docker.com>

namespaces/init.go

@@ -48,8 +48,8 @@ func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, syn
 	}
 
 	// We always read this as it is a way to sync with the parent as well
-	networkState, err := syncPipe.ReadFromParent()
-	if err != nil {
+	var networkState *network.NetworkState
+	if err := syncPipe.ReadFromParent(&networkState); err != nil {
 		return err
 	}
 

syncpipe/sync_pipe.go

@@ -6,8 +6,6 @@ import (
 	"io/ioutil"
 	"os"
 	"syscall"
-
-	"github.com/docker/libcontainer/network"
 )
 
 // SyncPipe allows communication to and from the child processes
@@ -39,8 +37,8 @@ func (s *SyncPipe) Parent() *os.File {
 	return s.parent
 }
 
-func (s *SyncPipe) SendToChild(networkState *network.NetworkState) error {
-	data, err := json.Marshal(networkState)
+func (s *SyncPipe) SendToChild(v interface{}) error {
+	data, err := json.Marshal(v)
 	if err != nil {
 		return err
 	}
@@ -63,18 +61,19 @@ func (s *SyncPipe) ReadFromChild() error {
 	return nil
 }
 
-func (s *SyncPipe) ReadFromParent() (*network.NetworkState, error) {
+func (s *SyncPipe) ReadFromParent(v interface{}) error {
 	data, err := ioutil.ReadAll(s.child)
 	if err != nil {
-		return nil, fmt.Errorf("error reading from sync pipe %s", err)
+		return fmt.Errorf("error reading from sync pipe %s", err)
 	}
-	var networkState *network.NetworkState
+
 	if len(data) > 0 {
-		if err := json.Unmarshal(data, &networkState); err != nil {
-			return nil, err
+		if err := json.Unmarshal(data, v); err != nil {
+			return err
 		}
 	}
-	return networkState, nil
+
+	return nil
 }
 
 func (s *SyncPipe) ReportChildError(err error) {

syncpipe/sync_pipe_test.go

@@ -3,10 +3,12 @@ package syncpipe
 import (
 	"fmt"
 	"testing"
-
-	"github.com/docker/libcontainer/network"
 )
 
+type testStruct struct {
+	Name string
+}
+
 func TestSendErrorFromChild(t *testing.T) {
 	pipe, err := NewSyncPipe()
 	if err != nil {
@@ -46,16 +48,16 @@ func TestSendPayloadToChild(t *testing.T) {
 
 	expected := "libcontainer"
 
-	if err := pipe.SendToChild(&network.NetworkState{VethHost: expected}); err != nil {
+	if err := pipe.SendToChild(testStruct{Name: expected}); err != nil {
 		t.Fatal(err)
 	}
 
-	payload, err := pipe.ReadFromParent()
-	if err != nil {
+	var s *testStruct
+	if err := pipe.ReadFromParent(&s); err != nil {
 		t.Fatal(err)
 	}
 
-	if payload.VethHost != expected {
-		t.Fatalf("expected veth host %q but received %q", expected, payload.VethHost)
+	if s.Name != expected {
+		t.Fatalf("expected name %q but received %q", expected, s.Name)
 	}
 }