use async version of fs.exists; fixes #69860

src/vs/workbench/contrib/debug/node/debugAdapter.ts

@@ -310,65 +310,67 @@ export class ExecutableDebugAdapter extends StreamDebugAdapter {
 		super();
 	}
 
-	startSession(): Promise<void> {
-
-		return new Promise<void>((resolve, reject) => {
-
-			// verify executables
-			if (this.adapterExecutable.command) {
-				if (path.isAbsolute(this.adapterExecutable.command)) {
-					if (!fs.existsSync(this.adapterExecutable.command)) {
-						reject(new Error(nls.localize('debugAdapterBinNotFound', "Debug adapter executable '{0}' does not exist.", this.adapterExecutable.command)));
+	async startSession(): Promise<void> {
+
+		const command = this.adapterExecutable.command;
+		const args = this.adapterExecutable.args;
+		const options = this.adapterExecutable.options || {};
+
+		try {
+			// verify executables asynchronously
+			if (command) {
+				if (path.isAbsolute(command)) {
+					const ok = await new Promise<boolean>(resolve => fs.exists(command, resolve));
+					if (!ok) {
+						throw new Error(nls.localize('debugAdapterBinNotFound', "Debug adapter executable '{0}' does not exist.", command));
 					}
 				} else {
 					// relative path
-					if (this.adapterExecutable.command.indexOf('/') < 0 && this.adapterExecutable.command.indexOf('\\') < 0) {
+					if (command.indexOf('/') < 0 && command.indexOf('\\') < 0) {
 						// no separators: command looks like a runtime name like 'node' or 'mono'
 						// TODO: check that the runtime is available on PATH
 					}
 				}
 			} else {
-				reject(new Error(nls.localize({ key: 'debugAdapterCannotDetermineExecutable', comment: ['Adapter executable file not found'] },
-					"Cannot determine executable for debug adapter '{0}'.", this.debugType)));
+				throw new Error(nls.localize({ key: 'debugAdapterCannotDetermineExecutable', comment: ['Adapter executable file not found'] },
+					"Cannot determine executable for debug adapter '{0}'.", this.debugType));
 			}
 
 			let env = objects.mixin({}, process.env);
-			if (this.adapterExecutable.options && this.adapterExecutable.options.env) {
-				env = objects.mixin(env, this.adapterExecutable.options.env);
+			if (options.env) {
+				env = objects.mixin(env, options.env);
 			}
 			delete env.VSCODE_PREVENT_FOREIGN_INSPECT;
 
-			if (this.adapterExecutable.command === 'node') {
-				if (Array.isArray(this.adapterExecutable.args) && this.adapterExecutable.args.length > 0) {
+			if (command === 'node') {
+				if (Array.isArray(args) && args.length > 0) {
 					const isElectron = !!process.env['ELECTRON_RUN_AS_NODE'] || !!process.versions['electron'];
-					const options: cp.ForkOptions = {
+					const forkOptions: cp.ForkOptions = {
 						env: env,
 						execArgv: isElectron ? ['-e', 'delete process.env.ELECTRON_RUN_AS_NODE;require(process.argv[1])'] : [],
 						silent: true
 					};
-					if (this.adapterExecutable.options && this.adapterExecutable.options.cwd) {
-						options.cwd = this.adapterExecutable.options.cwd;
+					if (options.cwd) {
+						forkOptions.cwd = options.cwd;
 					}
-					const child = cp.fork(this.adapterExecutable.args[0], this.adapterExecutable.args.slice(1), options);
+					const child = cp.fork(args[0], args.slice(1), forkOptions);
 					if (!child.pid) {
-						reject(new Error(nls.localize('unableToLaunchDebugAdapter', "Unable to launch debug adapter from '{0}'.", this.adapterExecutable.args[0])));
+						throw new Error(nls.localize('unableToLaunchDebugAdapter', "Unable to launch debug adapter from '{0}'.", args[0]));
 					}
 					this.serverProcess = child;
-					resolve();
 				} else {
-					reject(new Error(nls.localize('unableToLaunchDebugAdapterNoArgs', "Unable to launch debug adapter.")));
+					throw new Error(nls.localize('unableToLaunchDebugAdapterNoArgs', "Unable to launch debug adapter."));
 				}
 			} else {
-				const options: cp.SpawnOptions = {
+				const spawnOptions: cp.SpawnOptions = {
 					env: env
 				};
-				if (this.adapterExecutable.options && this.adapterExecutable.options.cwd) {
-					options.cwd = this.adapterExecutable.options.cwd;
+				if (options.cwd) {
+					spawnOptions.cwd = options.cwd;
 				}
-				this.serverProcess = cp.spawn(this.adapterExecutable.command, this.adapterExecutable.args, options);
-				resolve();
+				this.serverProcess = cp.spawn(command, args, spawnOptions);
 			}
-		}).then(_ => {
+
 			this.serverProcess.on('error', err => {
 				this._onError.fire(err);
 			});
@@ -401,10 +403,12 @@ export class ExecutableDebugAdapter extends StreamDebugAdapter {
 				});
 			}
 
+			// finally connect to the DA
 			this.connect(this.serverProcess.stdout, this.serverProcess.stdin);
-		}, (err: Error) => {
+
+		} catch (err) {
 			this._onError.fire(err);
-		});
+		}
 	}
 
 	stopSession(): Promise<void> {