process: split bootstrappers by threads that can run them

This patch split part of the bootstrappers into three files:

- `lib/internal/process/main_thread_only.js`: contains bootstrappers
  that can only be run in the main thread, including
  - `setupStdio` for the main thread that sets up `process.stdin`,
    `process.stdout`, `process.error` that may interact with external
    resources, e.g. TTY/File/Pipe/TCP sockets
  - `setupProcessMethods` that setup methods changing process-global
    states, e.g. `process.chdir`, `process.umask`, `process.setuid`
  - `setupSignalHandlers`
  - `setupChildProcessIpcChannel` that setup `process.send` for
    child processes.
- `lib/internal/process/worker_thread_only.js`: contains bootstrappers
  that can only be run in the worker threads, including
  - `setupStdio` for the worker thread that are streams to be
    manipulated or piped to the parent thread
- `lib/internal/process/per_thread.js`: contains bootstrappers
    that can be run in all threads, including:
  - `setupAssert` for `process.assert`
  - `setupCpuUsage` for `process.cpuUsage`
  - `setupHrtime` for `process.hrtime` and `process.hrtime.bigint`
  - `setupMemoryUsage` for `process.memoryUsage`
  - `setupConfig` for `process.config`
  - `setupKillAndExit` for `process.kill` and `process.exit`
  - `setupRawDebug` for `process._rawDebug`
  - `setupUncaughtExceptionCapture` for
    `process.setUncaughtExceptionCaptureCallback` and
    `process.hasUncaughtExceptionCaptureCallback`

Hopefully in the future we can sort more bootstrappers in
`boostrap/node.js` into these three files and further group
them into functions that can be run before creating the
snapshot / after loading the snapshot.

This patch also moves most of the `isMainThread` conditionals
into the main bootstrapper instead of letting them scattered around
special-casing different implementations.

PR-URL: #21378
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

Backport-PR-URL: #21866
Reviewed-By: Michaël Zasso <targos@protonmail.com>

lib/internal/bootstrap/node.js

@@ -44,33 +44,57 @@
 
     setupGlobalVariables();
 
-    const _process = NativeModule.require('internal/process');
-    _process.setupConfig(NativeModule._source);
-    _process.setupSignalHandlers();
-    _process.setupUncaughtExceptionCapture(exceptionHandlerState,
-                                           _shouldAbortOnUncaughtToggle);
+    // Bootstrappers for all threads, including worker threads and main thread
+    const perThreadSetup = NativeModule.require('internal/process/per_thread');
+    // Bootstrappers for the main thread only
+    let mainThreadSetup;
+    // Bootstrappers for the worker threads only
+    let workerThreadSetup;
+    if (isMainThread) {
+      mainThreadSetup = NativeModule.require(
+        'internal/process/main_thread_only'
+      );
+    } else {
+      workerThreadSetup = NativeModule.require(
+        'internal/process/worker_thread_only'
+      );
+    }
+
+    perThreadSetup.setupAssert();
+    perThreadSetup.setupConfig(NativeModule._source);
+
+    if (isMainThread) {
+      mainThreadSetup.setupSignalHandlers();
+    }
+
+    perThreadSetup.setupUncaughtExceptionCapture(exceptionHandlerState,
+                                                 _shouldAbortOnUncaughtToggle);
+
     NativeModule.require('internal/process/warning').setup();
     NativeModule.require('internal/process/next_tick').setup(_setupNextTick,
                                                              _setupPromises);
-    NativeModule.require('internal/process/stdio').setup();
-    NativeModule.require('internal/process/methods').setup(_chdir,
-                                                           _umask,
-                                                           _initgroups,
-                                                           _setegid,
-                                                           _seteuid,
-                                                           _setgid,
-                                                           _setuid,
-                                                           _setgroups);
+
+    if (isMainThread) {
+      mainThreadSetup.setupStdio();
+      mainThreadSetup.setupProcessMethods(
+        _chdir, _umask, _initgroups, _setegid, _seteuid,
+        _setgid, _setuid, _setgroups
+      );
+    } else {
+      workerThreadSetup.setupStdio();
+    }
 
     const perf = process.binding('performance');
     const {
       NODE_PERFORMANCE_MILESTONE_BOOTSTRAP_COMPLETE,
     } = perf.constants;
 
-    _process.setup_hrtime(_hrtime, _hrtimeBigInt);
-    _process.setup_cpuUsage(_cpuUsage);
-    _process.setupMemoryUsage(_memoryUsage);
-    _process.setupKillAndExit();
+    perThreadSetup.setupRawDebug(_rawDebug);
+    perThreadSetup.setupHrtime(_hrtime, _hrtimeBigInt);
+    perThreadSetup.setupCpuUsage(_cpuUsage);
+    perThreadSetup.setupMemoryUsage(_memoryUsage);
+    perThreadSetup.setupKillAndExit();
+
     if (global.__coverage__)
       NativeModule.require('internal/process/write-coverage').setup();
 
@@ -90,10 +114,9 @@
       NativeModule.require('internal/inspector_async_hook').setup();
     }
 
-    if (isMainThread)
-      _process.setupChannel();
-
-    _process.setupRawDebug(_rawDebug);
+    if (isMainThread) {
+      mainThreadSetup.setupChildProcessIpcChannel();
+    }
 
     const browserGlobals = !process._noBrowserGlobals;
     if (browserGlobals) {

lib/internal/process/main_thread_only.js

@@ -0,0 +1,127 @@
+'use strict';
+
+// This file contains process bootstrappers that can only be
+// run in the main thread
+
+const {
+  errnoException
+} = require('internal/errors');
+
+const {
+  setupProcessStdio,
+  getMainThreadStdio
+} = require('internal/process/stdio');
+
+const assert = require('assert').strict;
+
+function setupStdio() {
+  setupProcessStdio(getMainThreadStdio());
+}
+
+// Non-POSIX platforms like Windows don't have certain methods.
+// Workers also lack these methods since they change process-global state.
+function setupProcessMethods(_chdir, _umask, _initgroups, _setegid,
+                             _seteuid, _setgid, _setuid, _setgroups) {
+  if (_setgid !== undefined) {
+    setupPosixMethods(_initgroups, _setegid, _seteuid,
+                      _setgid, _setuid, _setgroups);
+  }
+
+  process.chdir = function chdir(...args) {
+    return _chdir(...args);
+  };
+
+  process.umask = function umask(...args) {
+    return _umask(...args);
+  };
+}
+
+function setupPosixMethods(_initgroups, _setegid, _seteuid,
+                           _setgid, _setuid, _setgroups) {
+
+  process.initgroups = function initgroups(...args) {
+    return _initgroups(...args);
+  };
+
+  process.setegid = function setegid(...args) {
+    return _setegid(...args);
+  };
+
+  process.seteuid = function seteuid(...args) {
+    return _seteuid(...args);
+  };
+
+  process.setgid = function setgid(...args) {
+    return _setgid(...args);
+  };
+
+  process.setuid = function setuid(...args) {
+    return _setuid(...args);
+  };
+
+  process.setgroups = function setgroups(...args) {
+    return _setgroups(...args);
+  };
+}
+
+// Worker threads don't receive signals.
+function setupSignalHandlers() {
+  const constants = process.binding('constants').os.signals;
+  const signalWraps = Object.create(null);
+  let Signal;
+
+  function isSignal(event) {
+    return typeof event === 'string' && constants[event] !== undefined;
+  }
+
+  // Detect presence of a listener for the special signal types
+  process.on('newListener', function(type) {
+    if (isSignal(type) && signalWraps[type] === undefined) {
+      if (Signal === undefined)
+        Signal = process.binding('signal_wrap').Signal;
+      const wrap = new Signal();
+
+      wrap.unref();
+
+      wrap.onsignal = process.emit.bind(process, type, type);
+
+      const signum = constants[type];
+      const err = wrap.start(signum);
+      if (err) {
+        wrap.close();
+        throw errnoException(err, 'uv_signal_start');
+      }
+
+      signalWraps[type] = wrap;
+    }
+  });
+
+  process.on('removeListener', function(type) {
+    if (signalWraps[type] !== undefined && this.listenerCount(type) === 0) {
+      signalWraps[type].close();
+      delete signalWraps[type];
+    }
+  });
+}
+
+function setupChildProcessIpcChannel() {
+  // If we were spawned with env NODE_CHANNEL_FD then load that up and
+  // start parsing data from that stream.
+  if (process.env.NODE_CHANNEL_FD) {
+    const fd = parseInt(process.env.NODE_CHANNEL_FD, 10);
+    assert(fd >= 0);
+
+    // Make sure it's not accidentally inherited by child processes.
+    delete process.env.NODE_CHANNEL_FD;
+
+    require('child_process')._forkChild(fd);
+    assert(process.send);
+  }
+}
+
+module.exports = {
+  setupStdio,
+  setupProcessMethods,
+  setupSignalHandlers,
+  setupChildProcessIpcChannel
+};