Asan, attmept to fix FreeBSD from stalling

[devnexen]

Summary

• Actually Asan on FreeBSD, due pthread_key_specific approach, during AsanTSDInit, remains stuck in this state.
• Here a proposal to simply save the context as is.

lib/asan/asan_posix.cc

 void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
   StartReportDeadlySignal();
   SignalContext sig(siginfo, context);
   ReportDeadlySignal(sig);
 }
 
 // ---------------------- TSD ---------------- {{{1
 
+#if SANITIZER_FREEBSD
+static void *_tsd = nullptr;
+#else
 static pthread_key_t tsd_key;
+#endif
 static bool tsd_key_inited = false;
 void AsanTSDInit(void (*destructor)(void *tsd)) {
   CHECK(!tsd_key_inited);
   tsd_key_inited = true;
+#if !SANITIZER_FREEBSD
   CHECK_EQ(0, pthread_key_create(&tsd_key, destructor));
+#endif
 }
 
 void *AsanTSDGet() {
   CHECK(tsd_key_inited);
+#if SANITIZER_FREEBSD
+  return _tsd;
+#else
   return pthread_getspecific(tsd_key);
+#endif
 }
 
 void AsanTSDSet(void *tsd) {
   CHECK(tsd_key_inited);
+#if SANITIZER_FREEBSD
+  _tsd = tsd;
+#else
   pthread_setspecific(tsd_key, tsd);
+#endif
 }
 
 void PlatformTSDDtor(void *tsd) {
   AsanThreadContext *context = (AsanThreadContext*)tsd;
   if (context->destructor_iterations > 1) {
     context->destructor_iterations--;
+#if SANITIZER_FREEBSD
+    _tsd = tsd;
+#else
     CHECK_EQ(0, pthread_setspecific(tsd_key, tsd));
+#endif
     return;
   }
   AsanThread::TSDDtor(tsd);
 }
 }  // namespace __asan
 
 #endif  // SANITIZER_POSIX