src/vs/workbench/api/node/extHostMcpNode.ts
217 LOC · 45 covered · 172 uncovered · 8 ranges · 1 concepts · 1 introducers · 6 tests
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/*---------------------------------------------------------------------------------------------
extHostMcpNode.ts ×8
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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import { ChildProcessWithoutNullStreams, spawn } from 'child_process';
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import { readFile } from 'fs/promises';
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import { homedir } from 'os';
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import type { RequestInit as UndiciRequestInit } from 'undici';
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import { parseEnvFile } from '../../../base/common/envfile.js';
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import { untildify } from '../../../base/common/labels.js';
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import { Lazy } from '../../../base/common/lazy.js';
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import { DisposableMap } from '../../../base/common/lifecycle.js';
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import * as path from '../../../base/common/path.js';
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import { URI } from '../../../base/common/uri.js';
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import { StreamSplitter } from '../../../base/node/nodeStreams.js';
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import { findExecutable } from '../../../base/node/processes.js';
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import { LogLevel } from '../../../platform/log/common/log.js';
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import { McpConnectionState, McpServerLaunch, McpServerTransportStdio, McpServerTransportType } from '../../contrib/mcp/common/mcpTypes.js';
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import { McpStdioStateHandler } from '../../contrib/mcp/node/mcpStdioStateHandler.js';
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import { CommonRequestInit, CommonResponse, ExtHostMcpService, McpHTTPHandle } from '../common/extHostMcp.js';
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export class NodeExtHostMpcService extends ExtHostMcpService {
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private nodeServers = this._register(new DisposableMap<number, McpStdioStateHandler>());
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protected override _startMcp(id: number, launch: McpServerLaunch, defaultCwd?: URI, errorOnUserInteraction?: boolean): void {
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if (launch.type === McpServerTransportType.Stdio) {
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this.startNodeMpc(id, launch, defaultCwd);
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} else if (launch.type === McpServerTransportType.HTTP) {
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this._sseEventSources.set(id, new McpHTTPHandleNode(id, launch, this._proxy, this._logService, errorOnUserInteraction));
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} else {
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super._startMcp(id, launch, defaultCwd, errorOnUserInteraction);
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}
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}
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override $stopMcp(id: number): void {
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const nodeServer = this.nodeServers.get(id);
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if (nodeServer) {
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nodeServer.stop(); // will get removed from map when process is fully stopped
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} else {
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super.$stopMcp(id);
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}
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}
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override $sendMessage(id: number, message: string): void {
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const nodeServer = this.nodeServers.get(id);
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if (nodeServer) {
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nodeServer.write(message);
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} else {
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super.$sendMessage(id, message);
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}
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}
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private async startNodeMpc(id: number, launch: McpServerTransportStdio, defaultCwd?: URI): Promise<void> {
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const onError = (err: Error | string) => this._proxy.$onDidChangeState(id, {
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state: McpConnectionState.Kind.Error,
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// eslint-disable-next-line local/code-no-any-casts
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code: err.hasOwnProperty('code') ? String((err as any).code) : undefined,
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message: typeof err === 'string' ? err : err.message,
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});
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// MCP servers are run on the same authority where they are defined, so
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// reading the envfile based on its path off the filesystem here is fine.
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const env = { ...process.env };
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if (launch.envFile) {
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try {
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for (const [key, value] of parseEnvFile(await readFile(launch.envFile, 'utf-8'))) {
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env[key] = value;
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}
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} catch (e) {
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onError(`Failed to read envFile '${launch.envFile}': ${e.message}`);
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return;
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}
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}
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for (const [key, value] of Object.entries(launch.env)) {
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// For PATH, we want to append to the existing PATH instead of overwriting it.
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if (key.toUpperCase() === 'PATH' && value !== null) {
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env[key] = env[key] ? `${env[key]}${path.delimiter}${String(value)}` : String(value);
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continue;
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}
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env[key] = value === null ? undefined : String(value);
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}
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let child: ChildProcessWithoutNullStreams;
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try {
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const home = homedir();
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let cwd = launch.cwd ? untildify(launch.cwd, home) : (defaultCwd?.fsPath || home);
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if (!path.isAbsolute(cwd)) {
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cwd = defaultCwd ? path.join(defaultCwd.fsPath, cwd) : path.join(home, cwd);
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}
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const { executable, args, shell } = await formatSubprocessArguments(
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untildify(launch.command, home),
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launch.args.map(a => untildify(a, home)),
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cwd,
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env
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);
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this._proxy.$onDidPublishLog(id, LogLevel.Debug, `Server command line: ${executable} ${args.join(' ')}`);
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child = spawn(executable, args, {
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stdio: 'pipe',
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cwd,
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env,
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shell,
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});
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} catch (e) {
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onError(e);
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return;
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}
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// Create the connection manager for graceful shutdown
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const connectionManager = new McpStdioStateHandler(child);
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this._proxy.$onDidChangeState(id, { state: McpConnectionState.Kind.Starting });
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child.stdout.pipe(new StreamSplitter('\n')).on('data', line => this._proxy.$onDidReceiveMessage(id, line.toString()));
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child.stdin.on('error', onError);
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child.stdout.on('error', onError);
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// Stderr handling is not currently specified https://github.com/modelcontextprotocol/specification/issues/177
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// Just treat it as generic log data for now
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child.stderr.pipe(new StreamSplitter('\n')).on('data', line => this._proxy.$onDidPublishLog(id, LogLevel.Warning, `[server stderr] ${line.toString().trimEnd()}`));
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child.on('spawn', () => this._proxy.$onDidChangeState(id, { state: McpConnectionState.Kind.Running }));
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child.on('error', e => {
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onError(e);
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});
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child.on('exit', code => {
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this.nodeServers.deleteAndDispose(id);
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if (code === 0 || connectionManager.stopped) {
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this._proxy.$onDidChangeState(id, { state: McpConnectionState.Kind.Stopped });
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} else {
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this._proxy.$onDidChangeState(id, {
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state: McpConnectionState.Kind.Error,
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message: `Process exited with code ${code}`,
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});
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}
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});
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this.nodeServers.set(id, connectionManager);
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}
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>
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class McpHTTPHandleNode extends McpHTTPHandle {
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private readonly _undici = new Lazy(() => import('undici'));
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protected override async _fetchInternal(url: string, init?: CommonRequestInit): Promise<CommonResponse> {
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// Note: imported async so that we can ensure we load undici after proxy patches have been applied
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const { fetch, Agent } = await this._undici.value;
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const undiciInit: UndiciRequestInit = { ...init };
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let httpUrl = url;
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const uri = URI.parse(url);
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if (uri.scheme === 'unix' || uri.scheme === 'pipe') {
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// By convention, we put the *socket path* as the URI path, and the *request path* in the fragment
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// So, set the dispatcher with the socket path
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undiciInit.dispatcher = new Agent({
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socketPath: uri.path,
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});
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// And then rewrite the URL to be http://localhost/<fragment>
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httpUrl = uri.with({
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scheme: 'http',
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authority: 'localhost', // HTTP always wants a host (not that we're using it), but if we're using a socket or pipe then localhost is sorta right anyway
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path: uri.fragment,
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}).toString(true);
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} else {
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return super._fetchInternal(url, init);
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}
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const undiciResponse = await fetch(httpUrl, undiciInit);
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return {
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status: undiciResponse.status,
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statusText: undiciResponse.statusText,
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headers: undiciResponse.headers as unknown as Headers, // undici `Headers` class no longer overlaps with lib.dom `Headers` (`SpecIterableIterator` vs `HeadersIterator`)
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body: undiciResponse.body as ReadableStream, // Way down in `ReadableStreamReadDoneResult<T>`, `value` is optional in the undici type but required (yet can be `undefined`) in the standard type
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url: undiciResponse.url,
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json: () => undiciResponse.json(),
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text: () => undiciResponse.text(),
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};
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}
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const windowsShellScriptRe = /\.(bat|cmd)$/i;
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export const escapeCmdArg = (s: string): string => `"${s.replace(/"/g, '""')}"`;
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/**
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* Formats arguments to avoid issues on Windows for CVE-2024-27980.
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*/
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export const formatSubprocessArguments = async (
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executable: string,
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args: ReadonlyArray<string>,
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cwd: string | undefined,
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env: Record<string, string | undefined>,
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) => {
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if (process.platform !== 'win32') {
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return { executable, args, shell: false };
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}
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const found = await findExecutable(executable, cwd, undefined, env);
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if (found && windowsShellScriptRe.test(found)) {
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return {
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executable: escapeCmdArg(found),
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args: args.map(escapeCmdArg),
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shell: true,
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};
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}
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return { executable, args, shell: false };
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};