feat(ses): Tame ModuleSource

packages/ses/src/lockdown.js

@@ -46,6 +46,7 @@ import { makeSafeEvaluator } from './make-safe-evaluator.js';
 import { initialGlobalPropertyNames } from './permits.js';
 import { tameFunctionToString } from './tame-function-tostring.js';
 import { tameDomains } from './tame-domains.js';
+import { tameModuleSource } from './tame-module-source.js';
 
 import { tameConsole } from './error/tame-console.js';
 import tameErrorConstructor from './error/tame-error-constructor.js';
@@ -286,6 +287,7 @@ export const repairIntrinsics = (options = {}) => {
   addIntrinsics(tameRegExpConstructor(regExpTaming));
   addIntrinsics(tameSymbolConstructor());
   addIntrinsics(shimArrayBufferTransfer());
+  addIntrinsics(tameModuleSource());
 
   addIntrinsics(getAnonymousIntrinsics());
 

packages/ses/src/tame-module-source.js

@@ -0,0 +1,51 @@
+import {
+  functionPrototype,
+  getPrototypeOf,
+  globalThis,
+  objectPrototype,
+  setPrototypeOf,
+} from './commons.js';
+
+export const tameModuleSource = () => {
+  const newIntrinsics = {};
+
+  const ModuleSource = globalThis.ModuleSource;
+  if (ModuleSource !== undefined) {
+    newIntrinsics.ModuleSource = ModuleSource;
+
+    // We introduce ModuleSource.[[Proto]] === AbstractModuleSource
+    // and ModuleSource.prototype.[[Proto]] === AbstractModuleSource.prototype
+    // if that layer is absent because the permitting system can more
+    // gracefully tolerate the absence of an expected prototype than the
+    // presence of an unexpected prototype,.
+    function AbstractModuleSource() {
+      // no-op safe to super()
+    }
+
+    const ModuleSourceProto = getPrototypeOf(ModuleSource);
+    if (ModuleSourceProto === functionPrototype) {
+      setPrototypeOf(ModuleSource, AbstractModuleSource);
+      newIntrinsics['%AbstractModuleSource%'] = AbstractModuleSource;
+      newIntrinsics['%AbstractModuleSourcePrototype%'] =
+        AbstractModuleSource.prototype;
+    } else {
+      newIntrinsics['%AbstractModuleSource%'] = ModuleSourceProto;
+      newIntrinsics['%AbstractModuleSourcePrototype%'] =
+        ModuleSourceProto.prototype;
+    }
+
+    const ModuleSourcePrototype = ModuleSource.prototype;
+    if (ModuleSourcePrototype !== undefined) {
+      newIntrinsics['%ModuleSourcePrototype%'] = ModuleSourcePrototype;
+
+      // ModuleSource.prototype.__proto__ should be the
+      // AbstractModuleSource.prototype.
+      const ModuleSourcePrototypeProto = getPrototypeOf(ModuleSourcePrototype);
+      if (ModuleSourcePrototypeProto === objectPrototype) {
+        setPrototypeOf(ModuleSource.prototype, AbstractModuleSource.prototype);
+      }
+    }
+  }
+
+  return newIntrinsics;
+};