daemon: Daemon.getPidContainer: change to accept "id" argument

This function didn't need the whole container, only its ID, so let's
use that as argument. This also makes it consistent with getIpcContainer.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/container_operations_unix.go

@@ -86,8 +86,7 @@ func (daemon *Daemon) getIpcContainer(id string) (*container.Container, error) {
 	return ctr, nil
 }
 
-func (daemon *Daemon) getPidContainer(ctr *container.Container) (*container.Container, error) {
-	id := ctr.HostConfig.PidMode.Container()
+func (daemon *Daemon) getPIDContainer(id string) (*container.Container, error) {
 	ctr, err := daemon.GetContainer(id)
 	if err != nil {
 		return nil, errdefs.InvalidParameter(err)

daemon/oci_linux.go

@@ -326,7 +326,7 @@ func WithNamespaces(daemon *Daemon, c *container.Container) coci.SpecOpts {
 		}
 		switch {
 		case pidMode.IsContainer():
-			pc, err := daemon.getPidContainer(c)
+			pc, err := daemon.getPIDContainer(pidMode.Container())
 			if err != nil {
 				return errors.Wrap(err, "failed to join PID namespace")
 			}