Ensure extension works with non-latin alphabets (#49)

server/src/lib/proc.ts

@@ -1,14 +1,38 @@
 import type {
-	ChildProcessWithoutNullStreams,
-	SpawnOptionsWithoutStdio,
+	ChildProcess,
+	SpawnSyncOptionsWithStringEncoding,
 } from 'child_process';
 import { processNotification } from './notificationChannels';
 import type { _Connection } from 'vscode-languageserver';
-import { spawn } from 'child_process';
+import { exec, spawn } from 'child_process';
 
 export class ProcessSpawner {
 	public constructor(private readonly _connection: _Connection) {}
 
+	private async _getCodePage(): Promise<number | null> {
+		return new Promise<number | null>((resolve) => {
+			// Get code page, which is sort of equivalent to charset/encoding
+			const chcpProc = spawn('chcp');
+			let stdout = '';
+			chcpProc.stdout.on('data', (chunk: Buffer | string) => {
+				stdout += chunk.toString();
+			});
+			chcpProc.on('exit', (code) => {
+				if (code === 0) {
+					const match = /:\s*(\d+)/.exec(stdout);
+					if (match) {
+						resolve(Number(match[1]));
+						return;
+					}
+				}
+				resolve(null);
+			});
+			chcpProc.on('error', () => {
+				resolve(null);
+			});
+		});
+	}
+
 	/**
 	 * Spawns a process in a way that guarantees that it will be killed
 	 * after given timeout. If VSCode is killed in the meantime, we still
@@ -18,9 +42,27 @@ export class ProcessSpawner {
 		binStr: string,
 		args: string[],
 		timeout: number,
-		options?: SpawnOptionsWithoutStdio
-	): Promise<ChildProcessWithoutNullStreams> {
-		const proc = spawn(binStr, args, options);
+		options: SpawnSyncOptionsWithStringEncoding
+	): Promise<ChildProcess> {
+		const proc = await (async () => {
+			if (process.platform === 'win32') {
+				const codePage = await this._getCodePage();
+				if (codePage && codePage !== 850) {
+					// Set codepage to 850 aka Latin 1
+					return exec(
+						`@chcp 850 >nul & cmd /d/s/c ${binStr} ${args.join(
+							' '
+						)}`,
+						{
+							cwd: options.cwd,
+							encoding: 'utf-8',
+						}
+					);
+				}
+			}
+			return spawn(binStr, args, options);
+		})();
+
 		if (proc.pid) {
 			await this._connection.sendNotification(processNotification, {
 				pid: proc.pid,