AU: Execute postinst asynchronously so that the D-Bus service is not blocked.

postinstall_runner_action.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_POSTINSTALL_RUNNER_ACTION_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_POSTINSTALL_RUNNER_ACTION_H__
 
 #include <string>
+
 #include "update_engine/action.h"
 #include "update_engine/install_plan.h"
 
 // The Postinstall Runner Action is responsible for running the postinstall
 // script of a successfully downloaded update.
 
 namespace chromeos_update_engine {
 
 class PostinstallRunnerAction;
 class NoneType;
 
 template<>
 class ActionTraits<PostinstallRunnerAction> {
  public:
   // Takes the device path as input
   typedef InstallPlan InputObjectType;
   // Passes the device path as output
   typedef InstallPlan OutputObjectType;
 };
 
 class PostinstallRunnerAction : public Action<PostinstallRunnerAction> {
  public:
   PostinstallRunnerAction() {}
   typedef ActionTraits<PostinstallRunnerAction>::InputObjectType
       InputObjectType;
   typedef ActionTraits<PostinstallRunnerAction>::OutputObjectType
       OutputObjectType;
   void PerformAction();
 
-  // This is a synchronous action, and thus TerminateProcessing() should
-  // never be called
+  // Note that there's no support for terminating this action currently.
   void TerminateProcessing() { CHECK(false); }
 
   // Debugging/logging
   static std::string StaticType() { return "PostinstallRunnerAction"; }
   std::string Type() const { return StaticType(); }
 
  private:
+  // Subprocess::Exec callback.
+  void CompletePostinstall(int return_code);
+  static void StaticCompletePostinstall(int return_code,
+                                        const std::string& output,
+                                        void* p);
+
+  std::string temp_rootfs_dir_;
+
   DISALLOW_COPY_AND_ASSIGN(PostinstallRunnerAction);
 };
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_POSTINSTALL_RUNNER_ACTION_H__