AU: Catch terminate signals and block exit if necessary.
Adds a global Terminator class to manage signals and exit blocking.
BUG=7392
TEST=unit tests, gmerged on device, initctl stop update-engine
Change-Id: I2291d4eb55240a6662b18ff834af161d957bce2f
Review URL: http://codereview.chromium.org/3608015
diff --git a/terminator.h b/terminator.h
new file mode 100644
index 0000000..1c014ea
--- /dev/null
+++ b/terminator.h
@@ -0,0 +1,45 @@
+// 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_TERMINATOR_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H__
+
+#include <signal.h>
+
+namespace chromeos_update_engine {
+
+// A class allowing graceful delayed exit.
+class Terminator {
+ public:
+ // Initializes the terminator and sets up signal handlers.
+ static void Init();
+
+ // 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; }
+
+ // 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:
+ // The signal handler.
+ static void HandleSignal(int signum);
+
+ static volatile sig_atomic_t exit_blocked_;
+ static volatile sig_atomic_t exit_requested_;
+};
+
+class ScopedTerminatorExitUnblocker {
+ public:
+ ~ScopedTerminatorExitUnblocker();
+};
+
+} // namespace chromeos_update_engine
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H__