feat: redesign preload APIs (#45329)

* feat: redesign preload APIs

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* docs: remove service-worker mentions for now

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix lint

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* remove service-worker ipc code

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* add filename

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: web preferences preload not included

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: missing common init

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: preload bundle script error

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

lib/sandboxed_renderer/preload.ts

@@ -0,0 +1,101 @@
+import { IPC_MESSAGES } from '@electron/internal/common/ipc-messages';
+import { ipcRendererInternal } from '@electron/internal/renderer/ipc-renderer-internal';
+
+import { EventEmitter } from 'events';
+
+interface PreloadContext {
+  loadedModules: Map<string, any>;
+  loadableModules: Map<string, any>;
+
+  /** Process object to pass into preloads. */
+  process: NodeJS.Process;
+
+  createPreloadScript: (src: string) => Function
+
+  /** Globals to be exposed to preload context. */
+  exposeGlobals: any;
+}
+
+export function createPreloadProcessObject (): NodeJS.Process {
+  const preloadProcess: NodeJS.Process = new EventEmitter() as any;
+
+  preloadProcess.getProcessMemoryInfo = () => {
+    return ipcRendererInternal.invoke<Electron.ProcessMemoryInfo>(IPC_MESSAGES.BROWSER_GET_PROCESS_MEMORY_INFO);
+  };
+
+  Object.defineProperty(preloadProcess, 'noDeprecation', {
+    get () {
+      return process.noDeprecation;
+    },
+    set (value) {
+      process.noDeprecation = value;
+    }
+  });
+
+  const { hasSwitch } = process._linkedBinding('electron_common_command_line');
+
+  // 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;
+  }
+
+  return preloadProcess;
+}
+
+// This is the `require` function that will be visible to the preload script
+function preloadRequire (context: PreloadContext, module: string) {
+  if (context.loadedModules.has(module)) {
+    return context.loadedModules.get(module);
+  }
+  if (context.loadableModules.has(module)) {
+    const loadedModule = context.loadableModules.get(module)!();
+    context.loadedModules.set(module, loadedModule);
+    return loadedModule;
+  }
+  throw new Error(`module not found: ${module}`);
+}
+
+// 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 (context: PreloadContext, preloadSrc: string) {
+  const globalVariables = [];
+  const fnParameters = [];
+  for (const [key, value] of Object.entries(context.exposeGlobals)) {
+    globalVariables.push(key);
+    fnParameters.push(value);
+  }
+  const preloadWrapperSrc = `(function(require, process, exports, module, ${globalVariables.join(', ')}) {
+  ${preloadSrc}
+  })`;
+
+  // eval in window scope
+  const preloadFn = context.createPreloadScript(preloadWrapperSrc);
+  const exports = {};
+
+  preloadFn(preloadRequire.bind(null, context), context.process, exports, { exports }, ...fnParameters);
+}
+
+/**
+ * Execute preload scripts within a sandboxed process.
+ */
+export function executeSandboxedPreloadScripts (context: PreloadContext, preloadScripts: ElectronInternal.PreloadScript[]) {
+  for (const { filePath, contents, error } of preloadScripts) {
+    try {
+      if (contents) {
+        runPreloadScript(context, contents);
+      } else if (error) {
+        throw error;
+      }
+    } catch (error) {
+      console.error(`Unable to load preload script: ${filePath}`);
+      console.error(error);
+      ipcRendererInternal.send(IPC_MESSAGES.BROWSER_PRELOAD_ERROR, filePath, error);
+    }
+  }
+}