Detect thread termination in LSan/NetBSD

[krytarowski]

Summary

Stop using the Linux solution with pthread_key_create(3).
This approach does not work on NetBSD, because calling
the thread destructor is not the latest operation on a POSIX
thread entity.

Detect _lwp_exit(2) call as it is really the latest operation
called from a detaching POSIX thread.

The pthread_key_create(3) solution also cannot be used
in early libc/libpthread initialization on NetBSD as the
system libraries are not bootstrapped enough.

Sponsored by <The NetBSD Foundation>

lib/lsan/lsan_interceptors.cc

 INTERCEPTOR(void, _ZdaPvRKSt9nothrow_t, void *ptr, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY; }
 
 #endif  // !SANITIZER_MAC
 
 
 ///// Thread initialization and finalization. /////
 
+#if !SANITIZER_NETBSD
 static unsigned g_thread_finalize_key;
 
 static void thread_finalize(void *v) {
   uptr iter = (uptr)v;
   if (iter > 1) {
     if (pthread_setspecific(g_thread_finalize_key, (void*)(iter - 1))) {
       Report("LeakSanitizer: failed to set thread key.\n");
       Die();
     }
     return;
   }
   ThreadFinish();
 }
+#endif
+
+#if SANITIZER_NETBSD
+INTERCEPTOR(void, _lwp_exit) {
+  ENSURE_LSAN_INITED;
+  ThreadFinish();
+  REAL(_lwp_exit)();
+}
+#define LSAN_MAYBE_INTERCEPT__LWP_EXIT INTERCEPT_FUNCTION(_lwp_exit)
+#else
+#define LSAN_MAYBE_INTERCEPT__LWP_EXIT
+#endif
 
 struct ThreadParam {
   void *(*callback)(void *arg);
   void *param;
   atomic_uintptr_t tid;
 };
 
 extern "C" void *__lsan_thread_start_func(void *arg) {
   ThreadParam *p = (ThreadParam*)arg;
   void* (*callback)(void *arg) = p->callback;
   void *param = p->param;
   // Wait until the last iteration to maximize the chance that we are the last
   // destructor to run.
+#if !SANITIZER_NETBSD
   if (pthread_setspecific(g_thread_finalize_key,
                           (void*)GetPthreadDestructorIterations())) {
     Report("LeakSanitizer: failed to set thread key.\n");
     Die();
   }
+#endif
   int tid = 0;
   while ((tid = atomic_load(&p->tid, memory_order_acquire)) == 0)
     internal_sched_yield();
   SetCurrentThread(tid);
   ThreadStart(tid, GetTid());
   atomic_store(&p->tid, 0, memory_order_release);
   return callback(param);
 }
void InitializeInterceptors() {
   LSAN_MAYBE_INTERCEPT_PVALLOC;
   LSAN_MAYBE_INTERCEPT_MALLOC_USABLE_SIZE;
   LSAN_MAYBE_INTERCEPT_MALLINFO;
   LSAN_MAYBE_INTERCEPT_MALLOPT;
   INTERCEPT_FUNCTION(pthread_create);
   INTERCEPT_FUNCTION(pthread_join);
   INTERCEPT_FUNCTION(_exit);
 
+  LSAN_MAYBE_INTERCEPT__LWP_EXIT;
+
+#if !SANITIZER_NETBSD
   if (pthread_key_create(&g_thread_finalize_key, &thread_finalize)) {
     Report("LeakSanitizer: failed to create thread key.\n");
     Die();
   }
+#endif
 }
 
 } // namespace __lsan