diff --git a/common/terminator.h b/common/terminator.h
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--- /dev/null
+++ b/common/terminator.h
@@ -0,0 +1,65 @@
+//
+// 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_