repl: fix crash when SharedArrayBuffer disabled (#30483)

Co-authored-by: Shelley Vohr <[email protected]>

patches/node/.patches

@@ -26,3 +26,4 @@ fix_crypto_tests_to_run_with_bssl.patch
 fix_account_for_debugger_agent_race_condition.patch
 fix_use_new_v8_error_message_property_access_format.patch
 add_should_read_node_options_from_env_option_to_disable_node_options.patch
+repl_fix_crash_when_sharedarraybuffer_disabled.patch

patches/node/repl_fix_crash_when_sharedarraybuffer_disabled.patch

@@ -0,0 +1,63 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Shelley Vohr <[email protected]>
+Date: Mon, 9 Aug 2021 18:42:15 +0200
+Subject: repl: fix crash when SharedArrayBuffer disabled
+
+It's possible for SharedArrayBuffers to be disabled with
+--no-harmony-sharedarraybuffer so we first need to check that this
+isn't the case before attempting to use them in the repl or a crash occurs.
+
+Upstreamed at https://github.com/nodejs/node/pull/39718.
+
+diff --git a/benchmark/worker/atomics-wait.js b/benchmark/worker/atomics-wait.js
+index a771b1813731edf4f0dd60f3505799e389f1d876..b9461677e2d7d1df192e752496e62cca837717b5 100644
+--- a/benchmark/worker/atomics-wait.js
++++ b/benchmark/worker/atomics-wait.js
+@@ -7,6 +7,10 @@ const bench = common.createBenchmark(main, {
+ });
+ 
+ function main({ n }) {
++  if (typeof SharedArrayBuffer === 'undefined') {
++    throw new Error('SharedArrayBuffers must be enabled to run this benchmark');
++  }
++
+   const i32arr = new Int32Array(new SharedArrayBuffer(4));
+   bench.start();
+   for (let i = 0; i < n; i++)
+diff --git a/lib/internal/main/worker_thread.js b/lib/internal/main/worker_thread.js
+index d6434ff96e118535bc6ded88ee4d2f0ff253a8f7..1b8894f44e71c6f25f1f50e84293006afe158513 100644
+--- a/lib/internal/main/worker_thread.js
++++ b/lib/internal/main/worker_thread.js
+@@ -9,7 +9,7 @@ const {
+   ArrayPrototypeSplice,
+   ObjectDefineProperty,
+   PromisePrototypeCatch,
+-  globalThis: { Atomics },
++  globalThis: { Atomics, SharedArrayBuffer },
+ } = primordials;
+ 
+ const {
+@@ -140,6 +140,9 @@ port.on('message', (message) => {
+     const originalCwd = process.cwd;
+ 
+     process.cwd = function() {
++      // SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
++      if (typeof SharedArrayBuffer === 'undefined') return originalCwd();
++
+       const currentCounter = Atomics.load(cwdCounter, 0);
+       if (currentCounter === lastCounter)
+         return cachedCwd;
+diff --git a/lib/internal/worker.js b/lib/internal/worker.js
+index 931bce0c518fc3355a9f94a7760556b6f0b75b96..99baa3e7f747bb3b351cb13c6ed512f2bb88812a 100644
+--- a/lib/internal/worker.js
++++ b/lib/internal/worker.js
+@@ -92,7 +92,8 @@ let cwdCounter;
+ 
+ const environmentData = new SafeMap();
+ 
+-if (isMainThread) {
++// SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
++if (isMainThread && typeof SharedArrayBuffer !== 'undefined') {
+   cwdCounter = new Uint32Array(new SharedArrayBuffer(4));
+   const originalChdir = process.chdir;
+   process.chdir = function(path) {