Bundle etcher-util with main app

forge.config.ts

@@ -7,6 +7,7 @@ import { MakerDMG } from '@electron-forge/maker-dmg';
 import { MakerAppImage } from '@reforged/maker-appimage';
 import { AutoUnpackNativesPlugin } from '@electron-forge/plugin-auto-unpack-natives';
 import { WebpackPlugin } from '@electron-forge/plugin-webpack';
+import { ResourcePlugin } from 'electron-forge-resource-plugin';
 
 import { mainConfig, rendererConfig } from './webpack.config';
 
@@ -30,13 +31,6 @@ const config: ForgeConfig = {
 
     // osxSign: {},
     // osxNotarize: {},
-
-    // One or more files to be copied directly into the app's `Contents/Resources` directory
-    // for macOS target platforms, and the `resources` directory for other target platforms.
-    // The resources directory can be referenced in code via `process.resourcesPath`.
-    extraResource: [
-      // TODO: child writer
-    ],
   },
   rebuildConfig: {},
   makers: [
@@ -152,8 +146,15 @@ const config: ForgeConfig = {
         ],
       },
     }),
+    new ResourcePlugin({
+      env: 'ETCHER_UTIL_BIN_PATH',
+      path: `out/sidecar/bin/etcher-util${process.platform === 'win32' ? '.exe' : ''}`,
+      build: {
+        command: 'npm rebuild mountutils && tsc --project tsconfig.sidecar.json && pkg out/sidecar/util/api.js -c pkg-sidecar.json --target node18 --output out/sidecar/bin/etcher-util',
+        sources: './lib/util/',
+      },
+    }),
   ],
 };
 
 export default config;
-

lib/gui/app/modules/api.ts

@@ -18,7 +18,6 @@ import * as os from 'os';
 import * as path from 'path';
 import * as packageJSON from '../../../../package.json';
 import * as permissions from '../../../shared/permissions';
-import { getAppPath } from '../../../shared/get-app-path';
 import * as errors from '../../../shared/errors';
 
 const THREADS_PER_CPU = 16;
@@ -27,8 +26,8 @@ const THREADS_PER_CPU = 16;
 // the stdout maxBuffer size to be exceeded when flashing
 ipc.config.silent = true;
 
-function writerArgv(): string[] {
-	let entryPoint = path.join(getAppPath(), 'generated', 'etcher-util');
+async function writerArgv(): Promise<string[]> {
+	let entryPoint = await window.etcher.getEtcherUtilPath();
 	// AppImages run over FUSE, so the files inside the mount point
 	// can only be accessed by the user that mounted the AppImage.
 	// This means we can't re-spawn Etcher as root from the same
@@ -75,7 +74,7 @@ async function spawnChild({
 	IPC_SERVER_ID: string;
 	IPC_SOCKET_ROOT: string;
 }) {
-	const argv = writerArgv();
+	const argv = await writerArgv();
 	const env = writerEnv(IPC_CLIENT_ID, IPC_SERVER_ID, IPC_SOCKET_ROOT);
 	if (withPrivileges) {
 		return await permissions.elevateCommand(argv, {

lib/gui/app/preload.ts

@@ -1,2 +1,12 @@
 // See the Electron documentation for details on how to use preload scripts:
 // https://www.electronjs.org/docs/latest/tutorial/process-model#preload-scripts
+
+import * as webapi from '../webapi';
+
+declare global {
+	interface Window {
+		etcher: typeof webapi;
+	}
+}
+
+window['etcher'] = webapi;

lib/gui/etcher.ts

@@ -242,6 +242,23 @@ electron.app.on('before-quit', () => {
 	process.exit(EXIT_CODES.SUCCESS);
 });
 
+// this is replaced at build-time with the path to etcher-util
+declare const ETCHER_UTIL_BIN_PATH: string;
+
+electron.ipcMain.handle('get-util-path', () => {
+	// Workaround the fact that the Resource forge plugin hardcodes
+	// the resource path to `resources` which is only valid on Linux
+	// and Windows builds -- it fails on macOS.
+	//
+	// We also can't just fallback to `process.resourcesPath` because
+	// that will always point to Electron's resource folder, which in
+	// dev builds using the Electron binary from node modules is not
+	// at all what we want, since our build artifacts reside in `/out`.
+	return process.env.NODE_ENV === 'development'
+		? ETCHER_UTIL_BIN_PATH
+		: ETCHER_UTIL_BIN_PATH.replace('resources', process.resourcesPath);
+});
+
 async function main(): Promise<void> {
 	if (!electron.app.requestSingleInstanceLock()) {
 		electron.app.quit();

lib/gui/webapi.ts

@@ -0,0 +1,13 @@
+//
+// Anything exported from this module will become available to the
+// renderer process via preload. They're accessible as `window.etcher.foo()`.
+//
+
+import { ipcRenderer } from 'electron';
+
+// FIXME: this is a workaround for the renderer to be able to find the etcher-util
+// binary. We should instead export a function that asks the main process to launch
+// the binary itself.
+export async function getEtcherUtilPath(): Promise<string> {
+	return await ipcRenderer.invoke('get-util-path');
+}

package.json

@@ -14,8 +14,6 @@
     "url": "[email protected]:balena-io/etcher.git"
   },
   "scripts": {
-    "build:rebuild-mountutils": "cd node_modules/mountutils && npm rebuild",
-    "build:sidecar": "npm run build:rebuild-mountutils && tsc --project tsconfig.sidecar.json && pkg build/util/api.js -c pkg-sidecar.json --target node18 --output generated/etcher-util",
     "flowzone-preinstall-linux": "sudo apt-get update && sudo apt-get install -y xvfb libudev-dev && cat < electron-builder.yml | yq e .deb.depends[] - | xargs -L1 echo | sed 's/|//g' | xargs -L1 sudo apt-get --ignore-missing install || true",
     "flowzone-preinstall-macos": "true",
     "flowzone-preinstall-windows": "npx node-gyp install",
@@ -106,6 +104,7 @@
     "chai": "4.3.7",
     "css-loader": "5.2.7",
     "electron": "^25.8.2",
+    "electron-forge-resource-plugin": "^1.0.0-alpha.6",
     "electron-mocha": "^11.0.2",
     "electron-notarize": "1.2.2",
     "electron-rebuild": "^3.2.9",

tsconfig.sidecar.json

@@ -12,7 +12,7 @@
     "moduleResolution": "Node",
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "outDir": "build"
+    "outDir": "out/sidecar"
   },
   "include": ["lib/util"]
 }