src: do not unnecessarily re-assign uv handle data

a555be2 re-assigned `async_.data` to indicate success or failure of the constructor. As the `HandleWrap` implementation uses that field to access the `HandleWrap` instance from the libuv handle, this introduced two issues: - It implicitly assumed that casting `MessagePort*` → `void*` → `HandleWrap*` would be valid. - It made the `HandleWrap::OnClose()` function fail with a `nullptr` dereference if the constructor did fail. In particular, the second issue made test/parallel/test-worker-cleanexit-with-moduleload.js` crash at least once in CI. Since re-assigning `async_.data` isn’t actually necessary here (only a leftover from earlier versions of that commit), fix this by using a local variable instead, and add a `CHECK` that provides better error messages for this type of issue in the future. Refs: #31605 PR-URL: #31696 Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

src/handle_wrap.cc

@@ -115,6 +115,7 @@ HandleWrap::HandleWrap(Environment* env,
 
 
 void HandleWrap::OnClose(uv_handle_t* handle) {
+ CHECK_NOT_NULL(handle->data);
  BaseObjectPtr<HandleWrap> wrap { static_cast<HandleWrap*>(handle->data) };
  wrap->Detach();
 

src/node_messaging.cc

@@ -488,10 +488,9 @@ MessagePort::MessagePort(Environment* env,
  CHECK_EQ(uv_async_init(env->event_loop(),
  &async_,
  onmessage), 0);
- async_.data = nullptr; // Reset later to indicate success of the constructor.
- auto cleanup = OnScopeLeave([&]() {
- if (async_.data == nullptr) Close();
- });
+ // Reset later to indicate success of the constructor.
+ bool succeeded = false;
+ auto cleanup = OnScopeLeave([&]() { if (!succeeded) Close(); });
 
  Local<Value> fn;
  if (!wrap->Get(context, env->oninit_symbol()).ToLocal(&fn))
@@ -508,7 +507,7 @@ MessagePort::MessagePort(Environment* env,
  return;
  emit_message_fn_.Reset(env->isolate(), emit_message_fn);
 
- async_.data = static_cast<void*>(this);
+ succeeded = true;
  Debug(this, "Created message port");
 }