Add the ability to defer the initialization of the SyzyAsan crash reporter.

syzygy/agent/asan/rtl_impl.h

Index: syzygy/agent/asan/rtl_impl.h
diff --git a/syzygy/agent/asan/rtl_impl.h b/syzygy/agent/asan/rtl_impl.h
index c9290bcb9c62f76417e62a61e7ec958287f9e00e..0c46ca17a514af33235d7e95357c0ff531992075 100644
--- a/syzygy/agent/asan/rtl_impl.h
+++ b/syzygy/agent/asan/rtl_impl.h
@@ -105,7 +105,7 @@ void WINAPI asan_SetOnExceptionCallback(OnExceptionCallback callback);
 //    experiement.
 typedef void(WINAPI* AsanExperimentCallback)(const char* experiment_name,
                                              const char* experiment_group);
-// Calls @p callback once for each experiement this runtime is performing.
+// Calls @p callback once for each experiment this runtime is performing.
 // @param callback a function that will be invoked recursively zero or more
 //     times to enumerate the experiments and their state.
 void WINAPI asan_EnumExperiments(AsanExperimentCallback callback);
@@ -113,6 +113,29 @@ void WINAPI asan_EnumExperiments(AsanExperimentCallback callback);
 
 int asan_CrashForException(EXCEPTION_POINTERS* exception);
 
+// This functions allows to manually initialize the crash reporter used by the

[chrisha, 2017/01/13 18:16:26]

allows manually initializing* and* is* used

[Sébastien Marchand, 2017/01/13 20:56:02]

Done.

+// runtime.
+//
+// It should only be used if the deferred initialization flag has been used by
+// the instrumented image (via the corresponding environment variable or at
+// instrumentation time) and should only be called once, trying to initialize

[chrisha, 2017/01/13 18:16:26]

once. Trying to initialize the crash handler a second time will result in
undefined behaviour.

[Sébastien Marchand, 2017/01/13 20:56:02]

Done.

+// the crash handler will result in a crash of the runtime library.
+//
+// Manually controlling the initialization of the crash reporter is useful when
+// there's no crash reporter available at initialization time (i.e. the
+// instrumented process hasn't initialized it yet). E.g. the instrumented image
+// should do something like this (additionally to using the deferred
+// initialization flag):

[chrisha, 2017/01/13 18:16:26]

In addition to instrumenting with the deferred initialization flag, the
instrumented image should do something like the following:

...

[Sébastien Marchand, 2017/01/13 20:56:02]

Done.

+//
+//   InitializeCrashReporter();
+//   typedef VOID(WINAPI* SyzyAsanInitializeCrashHandlerFn)();
+//   HMODULE handle = ::GetModuleHandle(L"syzyasan_rtl.dll");
+//   SyzyAsanInitializeCrashHandlerFn syzyasan_init_crash_handler =
+//       reinterpret_cast<SyzyAsanInitializeCrashHandlerFn>(
+//             ::GetProcAddress(handle, "asan_InitializeCrashHandler"));
+//   syzyasan_init_crash_handler();
+void WINAPI asan_InitializeCrashReporter();
+
 }  // extern "C"
 
 #endif  // SYZYGY_AGENT_ASAN_RTL_IMPL_H_