Fix ptmx issue on libcontainer

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)

pkg/libcontainer/namespaces/exec.go

@@ -50,7 +50,8 @@ func ExecContainer(container *libcontainer.Container) (pid int, err error) {
 	// command.Stderr = os.Stderr
 	command.SysProcAttr = &syscall.SysProcAttr{}
 	command.SysProcAttr.Cloneflags = flag
-	//command.ExtraFiles = []*os.File{master}
+
+	command.ExtraFiles = []*os.File{master}
 
 	println("vvvvvvvvv")
 	if err := command.Start(); err != nil {

pkg/libcontainer/namespaces/mount.go

@@ -41,7 +41,7 @@ func SetupNewMountNamespace(rootfs, console string, readonly bool) error {
 	if err := os.Remove(ptmx); err != nil && !os.IsNotExist(err) {
 		return err
 	}
-	if err := os.Symlink(filepath.Join(rootfs, "pts/ptmx"), ptmx); err != nil {
+	if err := os.Symlink("pts/ptmx", ptmx); err != nil {
 		return fmt.Errorf("symlink dev ptmx %s", err)
 	}