Function executeCommand

packages/cli/src/server/tools/exec-tools.ts:321–409

* Execute a command and return output, capping captured stdout/stderr so we * never accumulate arbitrary amounts of data in memory. If a stream blows * past `KILL_MULTIPLIER × cap` while we're already discarding bytes, we kill * the process — at that point we're throwing the data away anyway and

(
	command: string,
	dir: string,
	timeout: number,
	maxStdoutBytes: number,
	maxStderrBytes: number,
)

 * producer is just keeping the pipe pressurized.
 */
async function executeCommand(
	command: string,
	dir: string,
	timeout: number,
	maxStdoutBytes: number,
	maxStderrBytes: number,
): Promise<ExecuteResult> {
	return new Promise((resolve) => {
		const proc = spawn(command, {
			cwd: dir,
			shell: true,
			stdio: ['pipe', 'pipe', 'pipe'],
		});

		const stdoutCap = new StreamCapture(maxStdoutBytes);
		const stderrCap = new StreamCapture(maxStderrBytes);
		let killed = false;
		let killedForOversize = false;
		const stdoutKillAt = maxStdoutBytes * KILL_MULTIPLIER;
		const stderrKillAt = maxStderrBytes * KILL_MULTIPLIER;

		// Set timeout
		const timer = setTimeout(() => {
			killed = true;
			proc.kill('SIGTERM');
		}, timeout);

		proc.stdout?.on('data', (data: Buffer) => {
			stdoutCap.push(data);
			if (!killed && stdoutCap.totalBytes > stdoutKillAt) {
				killed = true;
				killedForOversize = true;
				proc.kill('SIGTERM');
			}
		});

		proc.stderr?.on('data', (data: Buffer) => {
			stderrCap.push(data);
			if (!killed && stderrCap.totalBytes > stderrKillAt) {
				killed = true;
				killedForOversize = true;
				proc.kill('SIGTERM');
			}
		});

		const finish = (code: number, errMessage?: string) => {
			clearTimeout(timer);
			const stdoutFinal = stdoutCap.finalize('stdout');
			const stderrFinal = stderrCap.finalize('stderr');
			let stderr = stderrFinal.content;
			if (errMessage) {
				stderr = stderr ? `${stderr}\n${errMessage}` : errMessage;
			}
			if (killedForOversize) {
				const note =
					`\nCommand was terminated because its output exceeded ` +
					`${formatBytes(stdoutKillAt)} (stdout) / ${formatBytes(stderrKillAt)} (stderr). ` +
					`Re-run with a narrower selection (head/tail/grep/sed).`;