AU: Catch terminate signals and block exit if necessary.

terminator.cc

Index: terminator.cc
diff --git a/terminator.cc b/terminator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1d33e324e86e608e1aa7767337c2a2fb59dc1fc5
--- /dev/null
+++ b/terminator.cc
@@ -0,0 +1,36 @@
+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.

[adlr, 2010/10/07 17:26:05]

it might be a bit more efficient to have the OS kill our process if we aren't
blocking exit, rather than handling the signal and then calling exit. On the
other hand, by always calling exit(), we are more consistent in how we exit,
since exit() calls global dtors, atexit() stuff, etc.

I think the code is fine, just wanted to mention it.

[petkov, 2010/10/07 17:29:31]

Yeah, thought about this. It seems better to exit cleanly by explicitly calling
exit. We can also exit glib loops, etc. if necessary. Also, we currently catch
only TERM signals. KILL will kill us directly.

I'll leave it as is.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "update_engine/terminator.h"
+
+#include <cstdlib>
+
+namespace chromeos_update_engine {
+
+volatile sig_atomic_t Terminator::exit_blocked_ = 0;
+volatile sig_atomic_t Terminator::exit_requested_ = 0;
+
+void Terminator::Init() {
+  signal(SIGTERM, HandleSignal);
+}
+
+void Terminator::Exit() {
+  exit(0);
+}
+
+void Terminator::HandleSignal(int signum) {
+  if (exit_blocked_ == 0) {
+    Exit();
+  }
+  exit_requested_ = 1;
+}
+
+ScopedTerminatorExitUnblocker::~ScopedTerminatorExitUnblocker() {
+  Terminator::set_exit_blocked(false);
+  if (Terminator::exit_requested()) {
+    Terminator::Exit();
+  }
+}
+
+}  // namespace chromeos_update_engine