Refactoring

@types/build-settings/index.d.ts

@@ -207,4 +207,17 @@ declare namespace __buildtimeSettings__ {
 	 * using two message channels
 	 */
 	const contextifyMessagePortWorkaroundCrash: boolean;
+
+	/**
+	 * Use eval to feature-detect function constructors
+	 *
+	 * If true, function constructors (e.g., AsyncFunction, Function, etc.)
+	 * will be obtained using eval (e.g., eval('(async ()=>{})')), which
+	 * works in environments that do not support the function declaration
+	 * syntax.
+	 *
+	 * If false, function constructors will be defined statically, without
+	 * feature detection.
+	 */
+	const featureDetectFunctionConstructors: boolean;
 }

esbuild.mjs

@@ -133,6 +133,37 @@ const exactRealtyClosureBuilderPlugin = {
 	},
 };
 
+/**
+ * @type {esbuild.Plugin}
+ **/
+const lotExportsBuilderPlugin = {
+	name: '@exact-realty/lot/exports',
+	setup(build) {
+		const extension = (() => {
+			switch (build.initialOptions.format) {
+				case 'cjs':
+					return 'cjs';
+				case 'esm':
+					return 'mjs';
+				case 'iife':
+					return 'js';
+			}
+		})();
+		build.onResolve(
+			{ filter: /^@exports\//, namespace: 'file' },
+			(args) => {
+				const path = `./${args.path
+					.slice(1)
+					.replace(/(?<=\.)js$/, extension)}`;
+				return {
+					path,
+					external: true,
+				};
+			},
+		);
+	},
+};
+
 const sequence = () => {
 	const generator = (function* () {
 		yield String(17);
@@ -153,7 +184,6 @@ const options = {
 	minify: true,
 	entryNames: '[name]',
 	platform: 'node',
-	external: ['esbuild'],
 	pure: ['Logger'],
 	define: {
 		'__buildtimeSettings__.buildTarget': '"generic"',
@@ -181,6 +211,7 @@ const options = {
 		'__buildtimeSettings__.isolationStategyIframeWorker': 'true',
 		'__buildtimeSettings__.contextifyMessagePort': 'true',
 		'__buildtimeSettings__.contextifyMessagePortWorkaroundCrash': 'true',
+		'__buildtimeSettings__.featureDetectFunctionConstructors': 'true',
 		// Enums
 		'EMessageTypes.SANDBOX_READY': EMessageTypesSequence.next(),
 		'EMessageTypes.REQUEST': EMessageTypesSequence.next(),
@@ -191,12 +222,11 @@ const options = {
 	},
 };
 
-void exactRealtyClosureBuilderPlugin;
-
 // TODO: Use Google Closure Compiler globally
 const plugins = [];
 
 plugins.push(
+	lotExportsBuilderPlugin,
 	inlineScripts({
 		...options,
 		target: 'es2015',

import_map.json

@@ -4,6 +4,7 @@
 		"@test/": "./test/",
 		"~trusted/": "./src/trusted/",
 		"~untrusted/": "./src/untrusted/",
+		"@exports/": "./src/exports/",
 		"@dist/": "./dist/"
 	}
 }

src/index.ts

@@ -13,9 +13,10 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-export { default as bareSandbox } from '~trusted/impl/bare/bareSandbox.js';
-export { default as browserSandbox } from '~trusted/impl/browser/browserSandbox.js';
-export { default as nodejsSandbox } from '~trusted/impl/nodejs/nodejsSandbox.js';
-export { default as workerSandbox } from '~trusted/impl/worker/workerSandbox.js';
+export { default as bareSandbox } from '@exports/bare.js';
+export { default as browserSandbox } from '@exports/browser.js';
+export { default, default as nodejsSandbox } from '@exports/nodejs.js';
+export { default as workerSandbox } from '@exports/worker.js';
+
 export { default as freezePrototypes } from '~untrusted/lib/freezePrototypes.js';
 export { default as hardenGlobals } from '~untrusted/lib/hardenGlobals.js';

src/trusted/impl/browser/browserSandbox.ts

@@ -118,17 +118,19 @@ const browserSandbox: ISandbox = async (
 		iframeSrcUrl + '#' + initMessageKeyA + '-' + initMessageKeyB,
 	);
 
-	const iframeStyles = {
-		['display']: 'none',
-		['height']: '1px',
-		['left']: '-9999px',
-		['opacity']: '0',
-		['position']: 'absolute',
-		['top']: '-9999px',
-		['visibility']: 'hidden',
-		['width']: '1px',
-	};
-	Object.assign(iframeContainer.style, iframeStyles);
+	/* List of CSS rules to attempt to ensure the iframe is never visible */
+	const iframeStyles: [string, string][] = [
+		['display', 'none'],
+		['position', 'absolute'],
+		['transform', 'scale(0)'],
+	];
+	iframeStyles.forEach((descriptor) => {
+		iframeContainer.style.setProperty(
+			descriptor[0],
+			descriptor[1],
+			'important',
+		);
+	});
 
 	if (typeof HTMLElement.prototype.attachShadow === 'function') {
 		const shadow = iframeContainer.attachShadow({ ['mode']: 'closed' });

src/untrusted/lib/functionTypeSpecimensList.ts

@@ -0,0 +1,51 @@
+/* Copyright © 2023 Exact Realty Limited.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+import { aFilter, aMap } from './utils.js';
+
+const functionTypeSpecimensList =
+	__buildtimeSettings__.featureDetectFunctionConstructors
+		? aFilter(
+				aMap(
+					[
+						'(function(){})',
+						'(function*(){})',
+						'(async function(){})',
+						'(async function*(){})',
+					],
+					(source, i) => {
+						try {
+							return (0, eval)(source);
+						} catch {
+							if (i === 0) {
+								return function () {
+									/**/
+								};
+							}
+						}
+					},
+				),
+				Boolean as unknown as {
+					(v?: FunctionConstructor): v is FunctionConstructor;
+				},
+		  )
+		: [
+				function () {},
+				function* () {},
+				async function () {},
+				async function* () {},
+		  ];
+
+export default functionTypeSpecimensList;

src/untrusted/lib/hardenGlobals.ts

@@ -15,9 +15,7 @@
 
 import {
 	EE,
-	aFilter,
 	aForEach,
-	aMap,
 	fnApply,
 	oDefineProperties,
 	oDefineProperty,
@@ -27,6 +25,7 @@ import {
 	oSetPrototypeOf,
 } from './utils.js';
 
+import functionTypeSpecimensList from './functionTypeSpecimensList.js';
 import global from './global.js';
 
 /**
@@ -127,33 +126,9 @@ const hardenGlobals: { (): void } = __buildtimeSettings__.hardenGlobals
 	? () => {
 			const FERAL_FUNCTION = hardenGlobals.constructor;
 
-			const list = aFilter(
-				aMap(
-					[
-						'(function(){})',
-						'(function*(){})',
-						'(async function(){})',
-						'(async function*(){})',
-					],
-					(source, i) => {
-						try {
-							return (0, eval)(source);
-						} catch {
-							if (i === 0)
-								return function () {
-									/**/
-								};
-						}
-					},
-				),
-				Boolean as unknown as {
-					(v?: FunctionConstructor): v is FunctionConstructor;
-				},
-			);
-
 			try {
 				// Attempt to tame function constructors
-				aForEach(list, (fnIntrinsic) => {
+				aForEach(functionTypeSpecimensList, (fnIntrinsic) => {
 					try {
 						const prototype = oGetPrototypeOf(fnIntrinsic);
 						const origConstructor = prototype.constructor;

tsconfig.json

@@ -18,6 +18,7 @@
 		"typeRoots": ["./node_modules/@types", "./@types"],
 		"paths": {
 			"@dist/*": ["./dist/*"],
+			"@exports/*": ["./src/exports/*"],
 			"~/*": ["./src/*"],
 			"@test/*": ["./test/*"],
 			"~trusted/*": ["./src/trusted/*"],