lib,repl: ignore non-canBeRequiredByUsers built-in

e.g. `wasi` under no `--experimental-wasi-unstable-preview1` flag shouldn't be pre-required. PR-URL: #39942 Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Zijian Liu <[email protected]>
nodejs · Sep 7, 2021 · c7222b3 · c7222b3
1 parent 8d5ed10
commit c7222b3
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Showing 4 changed files with 44 additions and 5 deletions.
diff --git a/lib/internal/main/eval_string.js b/lib/internal/main/eval_string.js
@@ -16,7 +16,7 @@ const { addBuiltinLibsToObject } = require('internal/modules/cjs/helpers');
 const { getOptionValue } = require('internal/options');
 
 prepareMainThreadExecution();
-addBuiltinLibsToObject(globalThis);
+addBuiltinLibsToObject(globalThis, '<eval>');
 markBootstrapComplete();
 
 const source = getOptionValue('--eval');

diff --git a/lib/internal/modules/cjs/helpers.js b/lib/internal/modules/cjs/helpers.js
@@ -131,9 +131,16 @@ function stripBOM(content) {
   return content;
 }
 
-function addBuiltinLibsToObject(object) {
+function addBuiltinLibsToObject(object, dummyModuleName) {
   // Make built-in modules available directly (loaded lazily).
-  const { builtinModules } = require('internal/modules/cjs/loader').Module;
+  const Module = require('internal/modules/cjs/loader').Module;
+  const { builtinModules } = Module;
+
+  // To require built-in modules in user-land and ignore modules whose
+  // `canBeRequiredByUsers` is false. So we create a dummy module object and not
+  // use `require()` directly.
+  const dummyModule = new Module(dummyModuleName);
+
   ArrayPrototypeForEach(builtinModules, (name) => {
     // Neither add underscored modules, nor ones that contain slashes (e.g.,
     // 'fs/promises') or ones that are already defined.
@@ -157,7 +164,7 @@ function addBuiltinLibsToObject(object) {
 
     ObjectDefineProperty(object, name, {
       get: () => {
-        const lib = require(name);
+        const lib = dummyModule.require(name);
 
         // Disable the current getter/setter and set up a new
         // non-enumerable property.

diff --git a/lib/repl.js b/lib/repl.js
@@ -1098,7 +1098,7 @@ REPLServer.prototype.createContext = function() {
     value: makeRequireFunction(replModule)
   });
 
-  addBuiltinLibsToObject(context);
+  addBuiltinLibsToObject(context, '<REPL>');
 
   return context;
 };

diff --git a/test/parallel/test-repl-built-in-modules.js b/test/parallel/test-repl-built-in-modules.js
@@ -0,0 +1,32 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const cp = require('child_process');
+
+function runREPLWithAdditionalFlags(flags) {
+  // Use -i to force node into interactive mode, despite stdout not being a TTY
+  const args = ['-i'].concat(flags);
+  const ret = cp.execFileSync(process.execPath, args, {
+    input: 'require(\'events\');\nrequire(\'wasi\');',
+    encoding: 'utf8',
+  });
+  return ret;
+}
+
+// Run REPL in normal mode.
+let stdout = runREPLWithAdditionalFlags([]);
+assert.match(stdout, /\[Function: EventEmitter\] {/);
+assert.match(
+  stdout,
+  /Uncaught Error: Cannot find module 'wasi'[\w\W]+- <repl>\n/);
+
+// Run REPL with '--experimental-wasi-unstable-preview1'
+stdout = runREPLWithAdditionalFlags([
+  '--experimental-wasi-unstable-preview1',
+]);
+assert.match(stdout, /\[Function: EventEmitter\] {/);
+assert.doesNotMatch(
+  stdout,
+  /Uncaught Error: Cannot find module 'wasi'[\w\W]+- <repl>\n/);
+assert.match(stdout, /{ WASI: \[class WASI\] }/);