process: allow reading umask in workers

Refs: https://github.com/nodejs/node/issues/25448
PR-URL: https://github.com/nodejs/node/pull/25526
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

doc/api/errors.md

@@ -1926,6 +1926,11 @@ All attempts at serializing an uncaught exception from a worker thread failed.
 The pathname used for the main script of a worker has an
 unknown file extension.
 
+<a id="ERR_WORKER_UNSUPPORTED_OPERATION"></a>
+### ERR_WORKER_UNSUPPORTED_OPERATION
+
+The requested functionality is not supported in worker threads.
+
 <a id="ERR_ZLIB_INITIALIZATION_FAILED"></a>
 ### ERR_ZLIB_INITIALIZATION_FAILED
 

doc/api/process.md

@@ -2007,7 +2007,8 @@ console.log(
 );
 ```
 
-This feature is not available in [`Worker`][] threads.
+[`Worker`][] threads are able to read the umask, however attempting to set the
+umask will result in a thrown exception.
 
 ## process.uptime()
 <!-- YAML

lib/internal/bootstrap/node.js

@@ -82,6 +82,10 @@ function startup() {
     process._startProfilerIdleNotifier =
       rawMethods._startProfilerIdleNotifier;
     process._stopProfilerIdleNotifier = rawMethods._stopProfilerIdleNotifier;
+  } else {
+    const wrapped = workerThreadSetup.wrapProcessMethods(rawMethods);
+
+    process.umask = wrapped.umask;
   }
 
   // Set up methods on the process object for all threads

lib/internal/errors.js

@@ -1001,4 +1001,6 @@ E('ERR_WORKER_UNSERIALIZABLE_ERROR',
 E('ERR_WORKER_UNSUPPORTED_EXTENSION',
   'The worker script extension must be ".js" or ".mjs". Received "%s"',
   TypeError);
+E('ERR_WORKER_UNSUPPORTED_OPERATION',
+  '%s is not supported in workers', TypeError);
 E('ERR_ZLIB_INITIALIZATION_FAILED', 'Initialization failed', Error);

lib/internal/process/worker_thread_only.js

@@ -15,6 +15,10 @@ const {
   WritableWorkerStdio
 } = require('internal/worker/io');
 
+const {
+  codes: { ERR_WORKER_UNSUPPORTED_OPERATION }
+} = require('internal/errors');
+
 let debuglog;
 function debug(...args) {
   if (!debuglog) {
@@ -118,8 +122,23 @@ function createWorkerFatalExeception(port) {
   };
 }
 
+// The execution of this function itself should not cause any side effects.
+function wrapProcessMethods(binding) {
+  function umask(mask) {
+    // process.umask() is a read-only operation in workers.
+    if (mask !== undefined) {
+      throw new ERR_WORKER_UNSUPPORTED_OPERATION('Setting process.umask()');
+    }
+
+    return binding.umask(mask);
+  }
+
+  return { umask };
+}
+
 module.exports = {
   initializeWorkerStdio,
   createMessageHandler,
-  createWorkerFatalExeception
+  createWorkerFatalExeception,
+  wrapProcessMethods
 };

src/node_process_methods.cc

@@ -50,6 +50,10 @@ using v8::Uint32;
 using v8::Uint32Array;
 using v8::Value;
 
+namespace per_process {
+Mutex umask_mutex;
+}   // namespace per_process
+
 // Microseconds in a second, as a float, used in CPUUsage() below
 #define MICROS_PER_SEC 1e6
 // used in Hrtime() below
@@ -220,6 +224,7 @@ static void Umask(const FunctionCallbackInfo<Value>& args) {
 
   CHECK_EQ(args.Length(), 1);
   CHECK(args[0]->IsUndefined() || args[0]->IsUint32());
+  Mutex::ScopedLock scoped_lock(per_process::umask_mutex);
 
   if (args[0]->IsUndefined()) {
     old = umask(0);
@@ -396,9 +401,9 @@ static void InitializeProcessMethods(Local<Object> target,
         target, "_stopProfilerIdleNotifier", StopProfilerIdleNotifier);
     env->SetMethod(target, "abort", Abort);
     env->SetMethod(target, "chdir", Chdir);
-    env->SetMethod(target, "umask", Umask);
   }
 
+  env->SetMethod(target, "umask", Umask);
   env->SetMethod(target, "_rawDebug", RawDebug);
   env->SetMethod(target, "memoryUsage", MemoryUsage);
   env->SetMethod(target, "cpuUsage", CPUUsage);

test/common/index.js

@@ -33,21 +33,20 @@ const {
   bits,
   hasIntl
 } = process.binding('config');
+const { isMainThread } = require('worker_threads');
 
 // Some tests assume a umask of 0o022 so set that up front. Tests that need a
 // different umask will set it themselves.
 //
-// process.umask() is not available in workers so we need to check for its
-// existence.
-if (process.umask)
+// Workers can read, but not set the umask, so check that this is the main
+// thread.
+if (isMainThread)
   process.umask(0o022);
 
 const noop = () => {};
 
 const hasCrypto = Boolean(process.versions.openssl);
 
-const { isMainThread } = require('worker_threads');
-
 // Check for flags. Skip this for workers (both, the `cluster` module and
 // `worker_threads`) and child processes.
 if (process.argv.length === 2 &&

test/parallel/test-fs-write-file-sync.js

@@ -23,7 +23,7 @@
 const common = require('../common');
 
 if (!common.isMainThread)
-  common.skip('process.umask is not available in Workers');
+  common.skip('Setting process.umask is not supported in Workers');
 
 const assert = require('assert');
 const path = require('path');

test/parallel/test-process-umask-mask.js

@@ -7,7 +7,7 @@ const common = require('../common');
 const assert = require('assert');
 
 if (!common.isMainThread)
-  common.skip('process.umask is not available in Workers');
+  common.skip('Setting process.umask is not supported in Workers');
 
 let mask;
 

test/parallel/test-process-umask.js

@@ -22,8 +22,15 @@
 'use strict';
 const common = require('../common');
 const assert = require('assert');
-if (!common.isMainThread)
-  common.skip('process.umask is not available in Workers');
+
+if (!common.isMainThread) {
+  assert.strictEqual(typeof process.umask(), 'number');
+  assert.throws(() => {
+    process.umask('0664');
+  }, { code: 'ERR_WORKER_UNSUPPORTED_OPERATION' });
+
+  common.skip('Setting process.umask is not supported in Workers');
+}
 
 // Note in Windows one can only set the "user" bits.
 let mask;