Refactor init actions into separate types

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

linux_setns_init.go

@@ -0,0 +1,35 @@
+// +build linux
+
+package libcontainer
+
+import (
+	"github.com/docker/libcontainer/apparmor"
+	"github.com/docker/libcontainer/configs"
+	"github.com/docker/libcontainer/label"
+	"github.com/docker/libcontainer/system"
+)
+
+// linuxSetnsInit performs the container's initialization for running a new process
+// inside an existing container.
+type linuxSetnsInit struct {
+	args   []string
+	config *configs.Config
+}
+
+func (l *linuxSetnsInit) Init() error {
+	if err := setupRlimits(l.config); err != nil {
+		return err
+	}
+	if err := finalizeNamespace(l.config); err != nil {
+		return err
+	}
+	if err := apparmor.ApplyProfile(l.config.AppArmorProfile); err != nil {
+		return err
+	}
+	if l.config.ProcessLabel != "" {
+		if err := label.SetProcessLabel(l.config.ProcessLabel); err != nil {
+			return err
+		}
+	}
+	return system.Execv(l.args[0], l.args[0:], l.config.Env)
+}