Address review comments

Ensure that the command is killed if we receive an error from the child
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

namespaces/exec.go

@@ -94,7 +94,9 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 	defer libcontainer.DeleteState(dataPath)
 
 	// Sync with child
-	if err := syncPipe.BlockOnChild(); err != nil {
+	if err := syncPipe.ReadFromChild(); err != nil {
+		command.Process.Kill()
+		command.Wait()
 		return -1, err
 	}
 

namespaces/init.go

@@ -30,7 +30,7 @@ import (
 func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, syncPipe *SyncPipe, args []string) (err error) {
 	defer func() {
 		if err != nil {
-			syncPipe.ReportError(err)
+			syncPipe.ReportChildError(err)
 		}
 	}()
 

namespaces/sync_pipe.go

@@ -60,10 +60,10 @@ func (s *SyncPipe) SendToChild(networkState *network.NetworkState) error {
 	return nil
 }
 
-func (s *SyncPipe) BlockOnChild() error {
+func (s *SyncPipe) ReadFromChild() error {
 	data, err := ioutil.ReadAll(s.parent)
 	if err != nil {
-		return nil
+		return err
 	}
 	if len(data) > 0 {
 		return fmt.Errorf("Child error: %s", string(data))
@@ -86,7 +86,7 @@ func (s *SyncPipe) ReadFromParent() (*network.NetworkState, error) {
 
 }
 
-func (s *SyncPipe) ReportError(err error) {
+func (s *SyncPipe) ReportChildError(err error) {
 	s.child.Write([]byte(err.Error()))
 	s.CloseChild()
 }