feat(ses): anticipate iterator helpers

packages/ses/package.json

@@ -69,6 +69,7 @@
     "ava": "^5.3.0",
     "babel-eslint": "^10.0.3",
     "c8": "^7.14.0",
+    "core-js": "^3.31.0",
     "eslint": "^8.42.0",
     "eslint-config-airbnb-base": "^15.0.0",
     "eslint-config-prettier": "^8.8.0",

packages/ses/src/get-anonymous-intrinsics.js

@@ -13,6 +13,7 @@ import {
   matchAllRegExp,
   matchAllSymbol,
   regexpPrototype,
+  globalThis,
 } from './commons.js';
 import { InertCompartment } from './compartment-shim.js';
 
@@ -134,5 +135,27 @@ export const getAnonymousIntrinsics = () => {
     '%InertCompartment%': InertCompartment,
   };
 
+  if (globalThis.Iterator) {
+    intrinsics['%IteratorHelperPrototype%'] = getPrototypeOf(
+      // eslint-disable-next-line @endo/no-polymorphic-call
+      globalThis.Iterator.from([]).take(0),
+    );
+    intrinsics['%WrapForValidIteratorPrototype%'] = getPrototypeOf(
+      // eslint-disable-next-line @endo/no-polymorphic-call
+      globalThis.Iterator.from({ next() {} }),
+    );
+  }
+
+  if (globalThis.AsyncInterator) {
+    intrinsics['%AsyncIteratorHelperPrototype%'] = getPrototypeOf(
+      // eslint-disable-next-line @endo/no-polymorphic-call
+      globalThis.AsyncIterator.from([]).take(0),
+    );
+    intrinsics['%WrapForValidAsyncIteratorPrototype%'] = getPrototypeOf(
+      // eslint-disable-next-line @endo/no-polymorphic-call
+      globalThis.AsyncIterator.from({ next() {} }),
+    );
+  }
+
   return intrinsics;
 };

packages/ses/src/permits-intrinsics.js

@@ -253,7 +253,7 @@ export default function whitelistIntrinsics(
    * Visit all properties for a permit.
    */
   function visitProperties(path, obj, permit) {
-    if (obj === undefined) {
+    if (obj === undefined || obj === null) {
       return;
     }
 

packages/ses/src/permits.js

@@ -76,6 +76,10 @@ export const universalPropertyNames = {
   URIError: 'URIError',
   WeakMap: 'WeakMap',
   WeakSet: 'WeakSet',
+  // https://github.com/tc39/proposal-iterator-helpers
+  Iterator: 'Iterator',
+  // https://github.com/tc39/proposal-async-iterator-helpers
+  AsyncIterator: 'AsyncIterator',
 
   // *** Other Properties of the Global Object
 
@@ -246,7 +250,7 @@ export const FunctionInstance = {
 };
 
 // AsyncFunction Instances
-const AsyncFunctionInstance = {
+export const AsyncFunctionInstance = {
   // This property is not mentioned in ECMA 262, but is present in V8 and
   // necessary for lockdown to succeed.
   '[[Proto]]': '%AsyncFunctionPrototype%',
@@ -1233,14 +1237,90 @@ export const permitted = {
 
   // *** Control Abstraction Objects
 
+  // https://github.com/tc39/proposal-iterator-helpers
+  Iterator: {
+    // Properties of the Iterator Constructor
+    '[[Proto]]': '%FunctionPrototype%',
+    prototype: '%IteratorPrototype%',
+    from: fn,
+  },
+
   '%IteratorPrototype%': {
     // The %IteratorPrototype% Object
     '@@iterator': fn,
+    // https://github.com/tc39/proposal-iterator-helpers
+    constructor: 'Iterator',
+    map: fn,
+    filter: fn,
+    take: fn,
+    drop: fn,
+    flatMap: fn,
+    reduce: fn,
+    toArray: fn,
+    forEach: fn,
+    some: fn,
+    every: fn,
+    find: fn,
+    '@@toStringTag': 'string',
+    // https://github.com/tc39/proposal-async-iterator-helpers
+    toAsync: fn,
+  },
+
+  // https://github.com/tc39/proposal-iterator-helpers
+  '%WrapForValidIteratorPrototype%': {
+    '[[Proto]]': '%IteratorPrototype%',
+    next: fn,
+    return: fn,
+  },
+
+  // https://github.com/tc39/proposal-iterator-helpers
+  '%IteratorHelperPrototype%': {
+    '[[Proto]]': '%IteratorPrototype%',
+    next: fn,
+    return: fn,
+    '@@toStringTag': 'string',
+  },
+
+  // https://github.com/tc39/proposal-async-iterator-helpers
+  AsyncIterator: {
+    // Properties of the Iterator Constructor
+    '[[Proto]]': '%FunctionPrototype%',
+    prototype: '%AsyncIteratorPrototype%',
+    from: fn,
   },
 
   '%AsyncIteratorPrototype%': {
     // The %AsyncIteratorPrototype% Object
     '@@asyncIterator': fn,
+    // https://github.com/tc39/proposal-async-iterator-helpers
+    constructor: 'AsyncIterator',
+    map: fn,
+    filter: fn,
+    take: fn,
+    drop: fn,
+    flatMap: fn,
+    reduce: fn,
+    toArray: fn,
+    forEach: fn,
+    some: fn,
+    every: fn,
+    find: fn,
+    '@@toStringTag': 'string',
+  },
+
+  // https://github.com/tc39/proposal-async-iterator-helpers
+  '%WrapForValidAsyncIteratorPrototype%': {
+    '[[Proto]]': '%AsyncIteratorPrototype%',
+    next: fn,
+    return: fn,
+  },
+
+  // https://github.com/tc39/proposal-async-iterator-helpers
+  '%AsyncIteratorHelperPrototype%': {
+    '[[Proto]]': 'Async%IteratorPrototype%',
+    next: fn,
+    return: fn,
+    '@@toStringTag': 'string',
   },
 
   '%InertGeneratorFunction%': {

packages/ses/test/test-anticipate-async-iterator-helpers-shimmed.js

@@ -0,0 +1,38 @@
+// KLUDGE HAZARD The core-js shims are written as sloppy code
+// and so introduce sloppy functions.
+import 'core-js/actual/async-iterator/index.js';
+import test from 'ava';
+import '../index.js';
+
+// KLUDGE HAZARD only for testing with the sloppy modules of the
+// core-js iterator shim.
+// We mutate the permits to tolerates the sloppy functions for testing
+// by sacrificing security. The caller and arguments properties of
+// sloppy functions violate ocap encapsulation rules.
+import { AsyncFunctionInstance } from '../src/permits.js';
+
+AsyncFunctionInstance.arguments = {};
+AsyncFunctionInstance.caller = {};
+
+// Skipped because the core-js shim seems to miss the
+// actual %AsyncIteratorPrototype%,
+// so it creates a new one, causing us to fail because lockdown correctly
+// detects the conflicting definitions.
+// TODO report the bug to core-js
+test.skip('shimmed async-iterator helpers', t => {
+  lockdown();
+
+  const AsyncIteratorHelperPrototype = Object.getPrototypeOf(
+    AsyncIterator.from([]).take(0),
+  );
+  t.assert(Object.isFrozen(AsyncIteratorHelperPrototype));
+
+  const WrapForValidAsyncIteratorPrototype = Object.getPrototypeOf(
+    AsyncIterator.from({
+      async next() {
+        return undefined;
+      },
+    }),
+  );
+  t.assert(Object.isFrozen(WrapForValidAsyncIteratorPrototype));
+});

packages/ses/test/test-anticipate-iterator-helpers-shimmed.js

@@ -0,0 +1,42 @@
+// KLUDGE HAZARD The core-js shims are written as sloppy code
+// and so introduce sloppy functions.
+import 'core-js/actual/iterator/index.js';
+import test from 'ava';
+import '../index.js';
+
+// KLUDGE HAZARD only for testing with the sloppy modules of the
+// core-js iterator shim.
+// We mutate the permits to tolerates the sloppy functions for testing
+// by sacrificing security. The caller and arguments properties of
+// sloppy functions violate ocap encapsulation rules.
+import { FunctionInstance } from '../src/permits.js';
+
+FunctionInstance.arguments = {};
+FunctionInstance.caller = {};
+
+test('shimmed iterator helpers', t => {
+  lockdown();
+
+  t.deepEqual(
+    (function* g(i) {
+      // eslint-disable-next-line no-plusplus
+      while (true) yield i++;
+    })(1)
+      .drop(1)
+      .take(5)
+      .filter(it => it % 2)
+      .map(it => it ** 2)
+      .toArray(),
+    [9, 25],
+  );
+
+  const IteratorHelperPrototype = Object.getPrototypeOf(
+    Iterator.from([]).take(0),
+  );
+  t.assert(Object.isFrozen(IteratorHelperPrototype));
+
+  const WrapForValidIteratorPrototype = Object.getPrototypeOf(
+    Iterator.from({ next() {} }),
+  );
+  t.assert(Object.isFrozen(WrapForValidIteratorPrototype));
+});

yarn.lock

@@ -4204,6 +4204,11 @@ core-js@^2.4.0:
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.6.12.tgz#d9333dfa7b065e347cc5682219d6f690859cc2ec"
   integrity sha512-Kb2wC0fvsWfQrgk8HU5lW6U/Lcs8+9aaYcy4ZFc6DDlo4nZ7n70dEgE5rtR0oG6ufKDUnrwfWL1mXR5ljDatrQ==
 
+core-js@^3.31.0:
+  version "3.31.0"
+  resolved "https://registry.yarnpkg.com/core-js/-/core-js-3.31.0.tgz#4471dd33e366c79d8c0977ed2d940821719db344"
+  integrity sha512-NIp2TQSGfR6ba5aalZD+ZQ1fSxGhDo/s1w0nx3RYzf2pnJxt7YynxFlFScP6eV7+GZsKO95NSjGxyJsU3DZgeQ==
+
 [email protected]:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"