src: wrap HostPort in ExclusiveAccess

I found it exceedingly hard to figure out if there is a race condition
where one thread reads the inspector agent's HostPort's properties while
another modifies them concurrently.

I think the answer is "no, there isn't" but with this commit use sites
are forced to unwrap the object (and acquire the mutex in the process),
making it a great deal easier to reason about correctness.

PR-URL: https://github.com/nodejs/node/pull/31717
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: David Carlier <devnexen@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/node_process_object.cc b/src/node_process_object.cc
index 7cf8c125009..ddbb58abe53 100644
--- a/src/node_process_object.cc
+++ b/src/node_process_object.cc
@@ -51,7 +51,8 @@ static void ProcessTitleSetter(Local<Name> property,
 static void DebugPortGetter(Local<Name> property,
                             const PropertyCallbackInfo<Value>& info) {
   Environment* env = Environment::GetCurrent(info);
-  int port = env->inspector_host_port()->port();
+  ExclusiveAccess<HostPort>::Scoped host_port(env->inspector_host_port());
+  int port = host_port->port();
   info.GetReturnValue().Set(port);
 }
 
@@ -60,7 +61,8 @@ static void DebugPortSetter(Local<Name> property,
                             const PropertyCallbackInfo<void>& info) {
   Environment* env = Environment::GetCurrent(info);
   int32_t port = value->Int32Value(env->context()).FromMaybe(0);
-  env->inspector_host_port()->set_port(static_cast<int>(port));
+  ExclusiveAccess<HostPort>::Scoped host_port(env->inspector_host_port());
+  host_port->set_port(static_cast<int>(port));
 }
 
 static void GetParentProcessId(Local<Name> property,