Remove profiler signal handler on shutdown

runtime/vm/signal_handler_android.cc

Index: runtime/vm/signal_handler_android.cc
diff --git a/runtime/vm/signal_handler_android.cc b/runtime/vm/signal_handler_android.cc
index d8ea14e0ae803ef8d3525fb2f6347d52b488794e..1ac0b8c606173942f36898b2a3d8efe808093356 100644
--- a/runtime/vm/signal_handler_android.cc
+++ b/runtime/vm/signal_handler_android.cc
@@ -84,11 +84,21 @@ void SignalHandler::Install(SignalAction action) {
   struct sigaction act;
   memset(&act, 0, sizeof(act));
   act.sa_sigaction = action;
+  sigemptyset(&act.sa_mask);
   act.sa_flags = SA_RESTART | SA_SIGINFO;
+  int r = sigaction(SIGPROF, &act, NULL);
+  ASSERT(r == 0);
+}
+
+
+void SignalHandler::Remove() {
+  // Ignore future SIGPROF signals because by default SIGPROF will terminate
+  // the process and we may have some signals in flight.
+  struct sigaction act;
+  memset(&act, 0, sizeof(act));
+  act.sa_handler = SIG_IGN;
   sigemptyset(&act.sa_mask);
-  // TODO(johnmccutchan): Do we care about restoring the signal handler?
-  struct sigaction old_act;
-  int r = sigaction(SIGPROF, &act, &old_act);
+  int r = sigaction(SIGPROF, &act, NULL);
   ASSERT(r == 0);
 }

[siva, 2015/04/07 18:18:07]

The normal protocol is to remember the old action and restore it when the new
action is removed.

The new action handler if it does not have any action for the signal should call
the old action handler if it is not SIG_IGN. In the profiler case this is
probably not needed as you handle all SIGPROF signals.

[Cutch, 2015/04/07 18:35:55]

The default SIGPROF handler terminates the process
(http://man7.org/linux/man-pages/man7/signal.7.html)