module: refactor modules bootstrap

PR-URL: https://github.com/nodejs/node/pull/29937
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

2 files changed, 64 insertions, 10 deletions

diff --git a/lib/internal/bootstrap/loaders.js b/lib/internal/bootstrap/loaders.js
index 775fea064e..48afed2556 100644
--- a/lib/internal/bootstrap/loaders.js
+++ b/lib/internal/bootstrap/loaders.js
@@ -220,7 +220,10 @@ NativeModule.prototype.compileForPublicLoader = function(needToSyncExports) {
   this.compile();
   if (needToSyncExports) {
     if (!this.exportKeys) {
-      this.exportKeys = Object.keys(this.exports);
+      // When using --expose-internals, we do not want to reflect the named
+      // exports from core modules as this can trigger unnecessary getters.
+      const internal = this.id.startsWith('internal/');
+      this.exportKeys = internal ? [] : Object.keys(this.exports);
     }
     this.getESMFacade();
     this.syncExports();
diff --git a/lib/internal/bootstrap/pre_execution.js b/lib/internal/bootstrap/pre_execution.js
index 1126fbcdd7..80ac97ee45 100644
--- a/lib/internal/bootstrap/pre_execution.js
+++ b/lib/internal/bootstrap/pre_execution.js
@@ -5,6 +5,7 @@ const { Object, SafeWeakMap } = primordials;
 const { getOptionValue } = require('internal/options');
 const { Buffer } = require('buffer');
 const { ERR_MANIFEST_ASSERT_INTEGRITY } = require('internal/errors').codes;
+const path = require('path');
 
 function prepareMainThreadExecution(expandArgv1 = false) {
   // Patch the process object with legacy properties and normalizations
@@ -404,7 +405,6 @@ function initializeESMLoader() {
         'The ESM module loader is experimental.',
         'ExperimentalWarning', undefined);
     }
-
     const {
       setImportModuleDynamicallyCallback,
       setInitializeImportMetaObjectCallback
@@ -414,14 +414,6 @@ function initializeESMLoader() {
     // track of for different ESM modules.
     setInitializeImportMetaObjectCallback(esm.initializeImportMetaObject);
     setImportModuleDynamicallyCallback(esm.importModuleDynamicallyCallback);
-    const userLoader = getOptionValue('--experimental-loader');
-    // If --experimental-loader is specified, create a loader with user hooks.
-    // Otherwise create the default loader.
-    if (userLoader) {
-      const { emitExperimentalWarning } = require('internal/util');
-      emitExperimentalWarning('--experimental-loader');
-    }
-    esm.initializeLoader(process.cwd(), userLoader);
   }
 }
 
@@ -446,11 +438,70 @@ function loadPreloadModules() {
   }
 }
 
+function resolveMainPath(main) {
+  const { toRealPath, Module: CJSModule } =
+      require('internal/modules/cjs/loader');
+
+  // Note extension resolution for the main entry point can be deprecated in a
+  // future major.
+  let mainPath = CJSModule._findPath(path.resolve(main), null, true);
+  if (!mainPath)
+    return;
+
+  const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
+  if (!preserveSymlinksMain)
+    mainPath = toRealPath(mainPath);
+
+  return mainPath;
+}
+
+function shouldUseESMLoader(mainPath) {
+  const experimentalModules = getOptionValue('--experimental-modules');
+  if (!experimentalModules)
+    return false;
+  const userLoader = getOptionValue('--experimental-loader');
+  if (userLoader)
+    return true;
+  // Determine the module format of the main
+  if (mainPath && mainPath.endsWith('.mjs'))
+    return true;
+  if (!mainPath || mainPath.endsWith('.cjs'))
+    return false;
+  const { readPackageScope } = require('internal/modules/cjs/loader');
+  const pkg = readPackageScope(mainPath);
+  return pkg && pkg.data.type === 'module';
+}
+
+function runMainESM(mainPath) {
+  const esmLoader = require('internal/process/esm_loader');
+  const { pathToFileURL } = require('internal/url');
+  const { hasUncaughtExceptionCaptureCallback } =
+      require('internal/process/execution');
+  return esmLoader.initializeLoader().then(() => {
+    const main = path.isAbsolute(mainPath) ?
+      pathToFileURL(mainPath).href : mainPath;
+    return esmLoader.ESMLoader.import(main).catch((e) => {
+      if (hasUncaughtExceptionCaptureCallback()) {
+        process._fatalException(e);
+        return;
+      }
+      internalBinding('errors').triggerUncaughtException(
+        e,
+        true /* fromPromise */
+      );
+    });
+  });
+}
+
+
 module.exports = {
   patchProcessObject,
+  resolveMainPath,
+  runMainESM,
   setupCoverageHooks,
   setupWarningHandler,
   setupDebugEnv,
+  shouldUseESMLoader,
   prepareMainThreadExecution,
   initializeDeprecations,
   initializeESMLoader,