(locally (declare (sb-ext:muffle-conditions sb-ext:compiler-note))
      (let ((flock (make-instance 'sb-posix:flock
                      :type sb-posix:f-wrlck
                      :whence sb-posix:seek-set
                      :start 0 :len 10))
            (pathname "fcntl.flock.1")
            kid-status)
        (catch 'test
          (with-open-file (f pathname :direction :output)
            (write-line "1234567890" f)
            (assert (zerop (sb-posix:fcntl f sb-posix:f-setlk flock)))
            (let ((pid (sb-posix:fork)))
              (if (zerop pid)
                  (progn
                    (multiple-value-bind (nope error)
                        (ignore-errors (sb-posix:fcntl f sb-posix:f-setlk flock))
                      (sb-ext:quit
                       :unix-status
                       (cond ((not (null nope)) 1)
                             ((= (sb-posix:syscall-errno error) sb-posix:eagain)
                              42)
                             (t 86))
                       :recklessly-p t #| don't delete the file |#)))
                  (progn
                    (setf kid-status
                          (sb-posix:wexitstatus
                           (nth-value
                            1 (sb-posix:waitpid pid 0))))
                    (throw 'test nil))))))
        kid-status))