fix(ext/node): worker_threads copies env object (#23536)

Most common argument to `env` option for `worker_threads.Worker` will be
`process.env`.

In Deno `process.env` is a `Proxy` which can't be cloned using
structured clone algorithm.

So to be safe, I'm creating a copy of actual object before it's sent to
the worker thread.

Ref #23522

2 files changed, 39 insertions, 2 deletions

diff --git a/ext/node/polyfills/worker_threads.ts b/ext/node/polyfills/worker_threads.ts
index 96aa02fe1..8f531368a 100644
--- a/ext/node/polyfills/worker_threads.ts
+++ b/ext/node/polyfills/worker_threads.ts
@@ -29,7 +29,7 @@ import { EventEmitter } from "node:events";
 import { BroadcastChannel } from "ext:deno_broadcast_channel/01_broadcast_channel.js";
 import process from "node:process";
 
-const { ObjectPrototypeIsPrototypeOf } = primordials;
+const { JSONParse, JSONStringify, ObjectPrototypeIsPrototypeOf } = primordials;
 const {
   Error,
   Symbol,
@@ -126,10 +126,18 @@ class NodeWorker extends EventEmitter {
     }
     this.#name = name;
 
+    // One of the most common usages will be to pass `process.env` here,
+    // but because `process.env` is a Proxy in Deno, we need to get a plain
+    // object out of it - otherwise we'll run in `DataCloneError`s.
+    // See https://github.com/denoland/deno/issues/23522.
+    let env_ = undefined;
+    if (options?.env) {
+      env_ = JSONParse(JSONStringify(options?.env));
+    }
     const serializedWorkerMetadata = serializeJsMessageData({
       workerData: options?.workerData,
       environmentData: environmentData,
-      env: options?.env,
+      env: env_,
     }, options?.transferList ?? []);
     const id = op_create_worker(
       {
diff --git a/tests/unit_node/worker_threads_test.ts b/tests/unit_node/worker_threads_test.ts
index a96896ce5..bc2becd66 100644
--- a/tests/unit_node/worker_threads_test.ts
+++ b/tests/unit_node/worker_threads_test.ts
@@ -10,6 +10,7 @@ import {
 import { fromFileUrl, relative, SEPARATOR } from "@std/path/mod.ts";
 import * as workerThreads from "node:worker_threads";
 import { EventEmitter, once } from "node:events";
+import process from "node:process";
 
 Deno.test("[node/worker_threads] BroadcastChannel is exported", () => {
   assertEquals<unknown>(workerThreads.BroadcastChannel, BroadcastChannel);
@@ -486,3 +487,31 @@ Deno.test({
     await worker.terminate();
   },
 });
+
+Deno.test({
+  name: "[node/worker_threads] Worker env using process.env",
+  async fn() {
+    const deferred = Promise.withResolvers<void>();
+    const worker = new workerThreads.Worker(
+      `
+      import { parentPort } from "node:worker_threads";
+      import process from "node:process";
+      parentPort.postMessage("ok");
+      `,
+      {
+        eval: true,
+        // Make sure this doesn't throw `DataCloneError`.
+        // See https://github.com/denoland/deno/issues/23522.
+        env: process.env,
+      },
+    );
+
+    worker.on("message", (data) => {
+      assertEquals(data, "ok");
+      deferred.resolve();
+    });
+
+    await deferred.promise;
+    await worker.terminate();
+  },
+});