electron/lib/sandboxed_renderer/init.ts

/* eslint no-eval: "off" */
/* global binding */
import * as events from 'events';
import { IPC_MESSAGES } from '@electron/internal/common/ipc-messages';

const { EventEmitter } = events;

process._linkedBinding = binding.get;

const v8Util = process._linkedBinding('electron_common_v8_util');
// Expose Buffer shim as a hidden value. This is used by C++ code to
// deserialize Buffer instances sent from browser process.
v8Util.setHiddenValue(global, 'Buffer', Buffer);
// The process object created by webpack is not an event emitter, fix it so
// the API is more compatible with non-sandboxed renderers.
for (const prop of Object.keys(EventEmitter.prototype) as (keyof typeof process)[]) {
  if (Object.prototype.hasOwnProperty.call(process, prop)) {
    delete process[prop];
  }
}
Object.setPrototypeOf(process, EventEmitter.prototype);

const { ipcRendererInternal } = require('@electron/internal/renderer/ipc-renderer-internal');
const ipcRendererUtils = require('@electron/internal/renderer/ipc-renderer-internal-utils');

const { preloadScripts, process: processProps } = ipcRendererUtils.invokeSync(IPC_MESSAGES.BROWSER_SANDBOX_LOAD);

const electron = require('electron');

const loadedModules = new Map<string, any>([
  ['electron', electron],
  ['electron/common', electron],
  ['electron/renderer', electron],
  ['events', events]
]);

const loadableModules = new Map<string, Function>([
  ['timers', () => require('timers')],
  ['url', () => require('url')]
]);

// ElectronApiServiceImpl will look for the "ipcNative" hidden object when
// invoking the 'onMessage' callback.
v8Util.setHiddenValue(global, 'ipcNative', {
  onMessage (internal: boolean, channel: string, ports: MessagePort[], args: any[], senderId: number) {
    const sender = internal ? ipcRendererInternal : electron.ipcRenderer;
    sender.emit(channel, { sender, senderId, ports }, ...args);
  }
});

// ElectronSandboxedRendererClient will look for the "lifecycle" hidden object when
v8Util.setHiddenValue(global, 'lifecycle', {
  onLoaded () {
    (process as events.EventEmitter).emit('loaded');
  },
  onExit () {
    (process as events.EventEmitter).emit('exit');
  },
  onDocumentStart () {
    (process as events.EventEmitter).emit('document-start');
  },
  onDocumentEnd () {
    (process as events.EventEmitter).emit('document-end');
  }
});

const { webFrameInit } = require('@electron/internal/renderer/web-frame-init');
webFrameInit();

// Pass different process object to the preload script.
const preloadProcess: NodeJS.Process = new EventEmitter() as any;

Object.assign(preloadProcess, binding.process);
Object.assign(preloadProcess, processProps);

Object.assign(process, binding.process);
Object.assign(process, processProps);

Object.defineProperty(preloadProcess, 'noDeprecation', {
  get () {
    return process.noDeprecation;
  },
  set (value) {
    process.noDeprecation = value;
  }
});

process.on('loaded', () => (preloadProcess as events.EventEmitter).emit('loaded'));
process.on('exit', () => (preloadProcess as events.EventEmitter).emit('exit'));
(process as events.EventEmitter).on('document-start', () => (preloadProcess as events.EventEmitter).emit('document-start'));
(process as events.EventEmitter).on('document-end', () => (preloadProcess as events.EventEmitter).emit('document-end'));

// This is the `require` function that will be visible to the preload script
function preloadRequire (module: string) {
  if (loadedModules.has(module)) {
    return loadedModules.get(module);
  }
  if (loadableModules.has(module)) {
    const loadedModule = loadableModules.get(module)!();
    loadedModules.set(module, loadedModule);
    return loadedModule;
  }
  throw new Error(`module not found: ${module}`);
}

// Process command line arguments.
const { hasSwitch } = process._linkedBinding('electron_common_command_line');
const { getWebPreference } = process._linkedBinding('electron_renderer_web_frame');

// Similar to nodes --expose-internals flag, this exposes _linkedBinding so
// that tests can call it to get access to some test only bindings
if (hasSwitch('unsafely-expose-electron-internals-for-testing')) {
  preloadProcess._linkedBinding = process._linkedBinding;
}

const contextIsolation = getWebPreference(window, 'contextIsolation');
const webviewTag = getWebPreference(window, 'webviewTag');
const isHiddenPage = getWebPreference(window, 'hiddenPage');
const rendererProcessReuseEnabled = getWebPreference(window, 'disableElectronSiteInstanceOverrides');
const usesNativeWindowOpen = true;
const guestInstanceId = getWebPreference(window, 'guestInstanceId') || null;
const openerId = getWebPreference(window, 'openerId') || null;

switch (window.location.protocol) {
  case 'devtools:': {
    // Override some inspector APIs.
    require('@electron/internal/renderer/inspector');
    break;
  }
  case 'chrome-extension:': {
    break;
  }
  case 'chrome:': {
    break;
  }
  default: {
    // Override default web functions.
    const { windowSetup } = require('@electron/internal/renderer/window-setup');
    windowSetup(guestInstanceId, openerId, isHiddenPage, usesNativeWindowOpen, rendererProcessReuseEnabled);
  }
}

// Load webview tag implementation.
if (process.isMainFrame) {
  const { webViewInit } = require('@electron/internal/renderer/web-view/web-view-init');
  webViewInit(contextIsolation, webviewTag, guestInstanceId);
}

// Wrap the script into a function executed in global scope. It won't have
// access to the current scope, so we'll expose a few objects as arguments:
//
// - `require`: The `preloadRequire` function
// - `process`: The `preloadProcess` object
// - `Buffer`: Shim of `Buffer` implementation
// - `global`: The window object, which is aliased to `global` by webpack.
function runPreloadScript (preloadSrc: string) {
  const preloadWrapperSrc = `(function(require, process, Buffer, global, setImmediate, clearImmediate, exports) {
  ${preloadSrc}
  })`;

  // eval in window scope
  const preloadFn = binding.createPreloadScript(preloadWrapperSrc);
  const { setImmediate, clearImmediate } = require('timers');

  preloadFn(preloadRequire, preloadProcess, Buffer, global, setImmediate, clearImmediate, {});
}

for (const { preloadPath, preloadSrc, preloadError } of preloadScripts) {
  try {
    if (preloadSrc) {
      runPreloadScript(preloadSrc);
    } else if (preloadError) {
      throw preloadError;
    }
  } catch (error) {
    console.error(`Unable to load preload script: ${preloadPath}`);
    console.error(error);

    ipcRendererInternal.send(IPC_MESSAGES.BROWSER_PRELOAD_ERROR, preloadPath, error);
  }
}

// Warn about security issues
if (process.isMainFrame) {
  const { securityWarnings } = require('@electron/internal/renderer/security-warnings');
  securityWarnings();
}