src: shutdown libuv before exit()

This ensures that no operations will be running on the libuv
threadpool, which is important because they may run into race
conditions with the global destructors being triggered from
`exit()`, such as in the added test example here.

PR-URL: https://github.com/nodejs/node/pull/35021
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

src/api/environment.cc

@@ -705,6 +705,7 @@ void DefaultProcessExitHandler(Environment* env, int exit_code) {
   env->set_can_call_into_js(false);
   env->stop_sub_worker_contexts();
   DisposePlatform();
+  uv_library_shutdown();
   exit(exit_code);
 }
 

test/parallel/test-crypto-op-during-process-exit.js

@@ -0,0 +1,28 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto) { common.skip('missing crypto'); }
+const assert = require('assert');
+const { generateKeyPair } = require('crypto');
+
+if (common.isWindows) {
+  // Remove this conditional once the libuv change is in Node.js.
+  common.skip('crashing due to https://github.com/libuv/libuv/pull/2983');
+}
+
+// Regression test for a race condition: process.exit() might lead to OpenSSL
+// cleaning up state from the exit() call via calling its destructor, but
+// running OpenSSL operations on another thread might lead to them attempting
+// to initialize OpenSSL, leading to a crash.
+// This test crashed consistently on x64 Linux on Node v14.9.0.
+
+generateKeyPair('rsa', {
+  modulusLength: 2048,
+  privateKeyEncoding: {
+    type: 'pkcs1',
+    format: 'pem'
+  }
+}, (err/* , publicKey, privateKey */) => {
+  assert.ifError(err);
+});
+
+setTimeout(() => process.exit(), common.platformTimeout(10));