fix: Use PowerShell to trigger UAC prompts (#328)

Author: mykola-mokhnach

lib/installer.js

@@ -4,7 +4,7 @@ import path from 'path';
 import { exec } from 'teen_process';
 import { log } from './logger';
 import { queryRegistry } from './registry';
-import { shellExec } from './utils';
+import { runElevated } from './utils';
 
 const POSSIBLE_WAD_INSTALL_ROOTS = [
   process.env['ProgramFiles(x86)'],
@@ -24,12 +24,17 @@ session.DoAction("CostFinalize")
 WScript.Echo session.Property("INSTALLFOLDER")
 `.replace(/\n/g, '\r\n');
 
+/**
+ *
+ * @param {string} installerGuid
+ * @returns {Promise<string>} install location
+ */
 async function fetchMsiInstallLocation (installerGuid) {
   const tmpRoot = await tempDir.openDir();
   const scriptPath = path.join(tmpRoot, 'get_wad_inst_location.vbs');
   try {
     await fs.writeFile(scriptPath, INST_LOCATION_SCRIPT_BY_GUID(installerGuid), 'latin1');
-    const {stdout} = await shellExec('cscript.exe', ['/Nologo', scriptPath]);
+    const {stdout} = await runElevated('cscript.exe', ['/Nologo', scriptPath]);
     return _.trim(stdout);
   } finally {
     await fs.rimraf(tmpRoot);
@@ -66,10 +71,13 @@ export const getWADExecutablePath = _.memoize(async function getWADInstallPath (
     );
     if (wadEntry) {
       log.debug(`Found MSI entry: ${JSON.stringify(wadEntry)}`);
-      const installerGuid = _.last(wadEntry.root.split('\\'));
+      const installerGuid = /** @type {string} */ (_.last(wadEntry.root.split('\\')));
       // WAD MSI installer leaves InstallLocation registry value empty,
       // so we need to be hacky here
-      const result = path.join(await fetchMsiInstallLocation(installerGuid), WAD_EXE_NAME);
+      const result = path.join(
+        await fetchMsiInstallLocation(installerGuid),
+        WAD_EXE_NAME
+      );
       log.debug(`Checking if WAD exists at '${result}'`);
       if (await fs.exists(result)) {
         return result;
@@ -93,6 +101,10 @@ export const getWADExecutablePath = _.memoize(async function getWADInstallPath (
   );
 });
 
+/**
+ *
+ * @returns {Promise<boolean>}
+ */
 export async function isAdmin () {
   try {
     await exec('fsutil.exe', ['dirty', 'query', process.env.SystemDrive || 'C:']);

lib/registry.js

@@ -1,5 +1,5 @@
 import _ from 'lodash';
-import { shellExec } from './utils';
+import { runElevated } from './utils';
 
 const REG = 'reg.exe';
 const ENTRY_PATTERN = /^\s+(\w+)\s+([A-Z_]+)\s*(.*)/;
@@ -62,7 +62,7 @@ function parseRegQueryOutput (output) {
 async function queryRegistry (root) {
   let stdout;
   try {
-    ({stdout} = await shellExec(REG, ['query', root, '/s']));
+    ({stdout} = await runElevated(REG, ['query', root, '/s']));
   } catch {
     return [];
   }

lib/utils.js

@@ -3,54 +3,46 @@ import { net } from 'appium/support';
 import { promisify } from 'node:util';
 import { exec } from 'node:child_process';
 import B from 'bluebird';
+import { log } from './logger';
 
 const execAsync = promisify(exec);
 
 /**
  * This API triggers UAC when necessary
- * unlike the 'spawn' call used by teen_process's exec.
- * See https://github.com/nodejs/node-v0.x-archive/issues/6797
  *
  * @param {string} cmd
  * @param {string[]} args
  * @param {import('node:child_process').ExecOptions & {timeoutMs?: number}} opts
  * @returns {Promise<{stdout: string; stderr: string;}>}
  * @throws {import('node:child_process').ExecException}
+ *
+ * Notes:
+ * - If the UAC prompt is cancelled by the user, Start-Process returns a non-zero exit code.
  */
-export async function shellExec(cmd, args = [], opts = {}) {
+export async function runElevated(cmd, args = [], opts = {}) {
   const {
     timeoutMs = 60 * 1000 * 5
   } = opts;
-  const fullCmd = [cmd, ...args].map(escapeWindowsArg).join(' ');
-  const { stdout, stderr } = await B.resolve(execAsync(fullCmd, opts))
-    .timeout(timeoutMs, `The command '${fullCmd}' timed out after ${timeoutMs}ms`);
+
+  const escapePSSingleQuoted = (/** @type {string} */ str) => `'${String(str).replace(/'/g, "''")}'`;
+  const psFilePath = escapePSSingleQuoted(cmd);
+  const psArgList = _.isEmpty(args) ? "''" : args.map(escapePSSingleQuoted).join(',');
+  // Build the PowerShell Start-Process command (safe quoting for inner tokens)
+  const psCommand = `Start-Process -FilePath ${psFilePath} -ArgumentList ${psArgList} -Verb RunAs`;
+  // Wrap the PowerShell command in double-quotes for the outer shell call.
+  // We avoid additional interpolation here by using only single-quoted literals inside the PS command.
+  const fullCmd = `powershell -NoProfile -Command "${psCommand}"`;
+  log.debug(`Executing command: ${fullCmd}`);
+  const { stdout, stderr } = /** @type {any} */ (
+    await B.resolve(execAsync(fullCmd, opts))
+      .timeout(timeoutMs, `The command '${fullCmd}' timed out after ${timeoutMs}ms`)
+  );
   return {
     stdout: _.isString(stdout) ? stdout : stdout.toString(),
     stderr: _.isString(stderr) ? stderr : stderr.toString(),
   };
 }
 
-/**
- * Escapes a string to be used as a Windows command line argument
- *
- * @param {string} arg
- * @returns {string}
- */
-function escapeWindowsArg(arg) {
-  if (!arg) {
-    return '""';
-  }
-
-  const needsQuotes = /[\s"]/g.test(arg);
-  if (!needsQuotes) {
-    return arg;
-  }
-
-  // Escape double quotes and backslashes before quotes
-  const escaped = arg.replace(/(\\*)"/g, '$1$1\\"').replace(/(\\+)$/, '$1$1');
-  return `"${escaped}"`;
-}
-
 /**
  *
  * @param {string} srcUrl

scripts/install-wad.mjs

@@ -42,7 +42,7 @@ function parseNextPageUrl(headers) {
 /**
  * https://docs.github.com/en/rest/releases/releases?apiVersion=2022-11-28#list-releases
  *
- * @returns {Promise<ReleaseInfo[]}
+ * @returns {Promise<ReleaseInfo[]>}
  */
 async function listReleases() {
   /** @type {Record<string, any>[]} */