common/terminator.h

//
// Copyright (C) 2012 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#ifndef UPDATE_ENGINE_COMMON_TERMINATOR_H_
#define UPDATE_ENGINE_COMMON_TERMINATOR_H_

#include <signal.h>

#include <gtest/gtest_prod.h>  // for FRIEND_TEST

namespace chromeos_update_engine {

// A class allowing graceful delayed exit.
class Terminator {
 public:
  // Initializes the terminator and sets up signal handlers.
  static void Init();
  static void Init(int exit_status);

  // Terminates the current process.
  static void Exit();

  // Set to true if the terminator should block termination requests in an
  // attempt to block exiting.
  static void set_exit_blocked(bool block) { exit_blocked_ = block ? 1 : 0; }
  static bool exit_blocked() { return exit_blocked_ != 0; }

  // Returns true if the system is trying to terminate the process, false
  // otherwise. Returns true only if exit was blocked when the termination
  // request arrived.
  static bool exit_requested() { return exit_requested_ != 0; }

 private:
  FRIEND_TEST(TerminatorTest, HandleSignalTest);
  FRIEND_TEST(TerminatorDeathTest, ScopedTerminatorExitUnblockerExitTest);

  // The signal handler.
  static void HandleSignal(int signum);

  static volatile sig_atomic_t exit_status_;
  static volatile sig_atomic_t exit_blocked_;
  static volatile sig_atomic_t exit_requested_;
};

class ScopedTerminatorExitUnblocker {
 public:
  ~ScopedTerminatorExitUnblocker();
};

}  // namespace chromeos_update_engine

#endif  // UPDATE_ENGINE_COMMON_TERMINATOR_H_