Function acquireLockViaExclusiveOpen

src/mcp/daemon.ts:585–599

(pidPath: string, info: DaemonLockInfo)

 * window between create and write. Exported for testing.
 */
export function acquireLockViaExclusiveOpen(pidPath: string, info: DaemonLockInfo): boolean {
  let fd: number;
  try {
    fd = fs.openSync(pidPath, 'wx', 0o600); // O_CREAT | O_EXCL | O_WRONLY
  } catch (err: unknown) {
    if ((err as NodeJS.ErrnoException).code === 'EEXIST') return false;
    throw err;
  }
  try {
    fs.writeSync(fd, encodeLockInfo(info));
  } finally {
    fs.closeSync(fd);
  }
  return true;
}

/**
 * Remove a stale pidfile, but only if it still names a dead process. Re-reads