Alarm() on crystal lang

alarm.cr

lib LibC
  ITIMER_REAL    =       0
  ITIMER_VIRTUAL =       1
  ITIMER_PROF    =       2
  
  struct Itimerval
    it_interval : Timeval
    it_value : Timeval
  end
  struct Timeval
    tv_sec : Long
    tv_usec : Int
  end

  fun setitimer(which : Int, new_value : Itimerval*, old_value : Itimerval*) : Int
  fun getitimer(which : Int, curr_value : Itimerval*) : Int
end

# Call alarm() in 5 seconds, using real time timer (LibC::ITIMER_REAL) 
value = LibC::Timeval.new(tv_sec: 5.seconds)
timer_value = LibC::Itimerval.new(it_value: value)
old_value = LibC::Itimerval.new # this is required by setitimer
LibC.setitimer(LibC::ITIMER_REAL, pointerof(timer_value), pointerof(old_value))

Signal::ALRM.trap do
  raise "Timeout!"
end

sleep 10