src: mark ArrayBuffers with free callbacks as untransferable

More precisely, make them untransferable if they were created through
*our* APIs, because those do not follow the improved free callback
mechanism that V8 uses now. All other ArrayBuffers can be transferred
between threads now, the assumption being that they were created in a
clean way that follows the V8 API on this.

This addresses a TODO comment.

Refs: https://github.com/nodejs/node/pull/30339#issuecomment-552225353

PR-URL: https://github.com/nodejs/node/pull/30475
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>

3 files changed, 53 insertions, 0 deletions

diff --git a/test/addons/worker-buffer-callback/binding.cc b/test/addons/worker-buffer-callback/binding.cc
new file mode 100644
index 0000000000..a40876ebb5
--- /dev/null
+++ b/test/addons/worker-buffer-callback/binding.cc
@@ -0,0 +1,29 @@
+#include <node.h>
+#include <node_buffer.h>
+#include <v8.h>
+
+using v8::Context;
+using v8::Isolate;
+using v8::Local;
+using v8::Object;
+using v8::Value;
+
+char data[] = "hello";
+
+void Initialize(Local<Object> exports,
+                Local<Value> module,
+                Local<Context> context) {
+  Isolate* isolate = context->GetIsolate();
+  exports->Set(context,
+               v8::String::NewFromUtf8(
+                   isolate, "buffer", v8::NewStringType::kNormal)
+                   .ToLocalChecked(),
+               node::Buffer::New(
+                   isolate,
+                   data,
+                   sizeof(data),
+                   [](char* data, void* hint) {},
+                   nullptr).ToLocalChecked()).Check();
+}
+
+NODE_MODULE_CONTEXT_AWARE(NODE_GYP_MODULE_NAME, Initialize)
diff --git a/test/addons/worker-buffer-callback/binding.gyp b/test/addons/worker-buffer-callback/binding.gyp
new file mode 100644
index 0000000000..55fbe7050f
--- /dev/null
+++ b/test/addons/worker-buffer-callback/binding.gyp
@@ -0,0 +1,9 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'sources': [ 'binding.cc' ],
+      'includes': ['../common.gypi'],
+    }
+  ]
+}
diff --git a/test/addons/worker-buffer-callback/test.js b/test/addons/worker-buffer-callback/test.js
new file mode 100644
index 0000000000..b04984f157
--- /dev/null
+++ b/test/addons/worker-buffer-callback/test.js
@@ -0,0 +1,15 @@
+'use strict';
+const common = require('../../common');
+const assert = require('assert');
+const { MessageChannel } = require('worker_threads');
+const { buffer } = require(`./build/${common.buildType}/binding`);
+
+// Test that buffers allocated with a free callback through our APIs are not
+// transfered.
+
+const { port1 } = new MessageChannel();
+const origByteLength = buffer.byteLength;
+port1.postMessage(buffer, [buffer.buffer]);
+
+assert.strictEqual(buffer.byteLength, origByteLength);
+assert.notStrictEqual(buffer.byteLength, 0);