From: Joel VanderWerf <vjoel@...>
Date: 2004-05-10T18:02:25+09:00
Subject: Re: setting the hardware clock from ruby

Joel VanderWerf wrote:
> 
> Anybody happen to know if there is a platform independent way of setting 
> the hardware clock from ruby? I'm primarily interested in Windows at the 
> moment (for a port of some QNX code), so it can probably be done with 
> Win32API (or Ruby/DL, now). I didn't find much under "clock" on ruby 
> talk or "ruby set clock" on google. Any suggestions appreciated...

Setting local time on windows turned out to be an easy exercise in 
Ruby/DL. For posterity, here's the code:

require "dl/import"
require "dl/struct"

module Kernel32
   extend DL::Importable
   dlload 'kernel32'

   SYSTEMTIME = struct [
     "WORD wYear",
     "WORD wMonth",
     "WORD wDayOfWeek",
     "WORD wDay",
     "WORD wHour",
     "WORD wMinute",
     "WORD wSecond",
     "WORD wMilliseconds",
   ]

   # These use GMT.
   extern "void GetSystemTime(SYSTEMTIME*)"
   extern "BOOL SetSystemTime(const SYSTEMTIME*)"

   # These use local time, like ruby's Time.now.
   extern "void GetLocalTime(SYSTEMTIME*)"
   extern "BOOL SetLocalTime(const SYSTEMTIME*)"
end

# +time+ is a Time
def set_clock(time)
   local_time = Kernel32::SYSTEMTIME.malloc

   local_time.wYear          = time.year
   local_time.wMonth         = time.month
   local_time.wDay           = time.day
   local_time.wHour          = time.hour
   local_time.wMinute        = time.min
   local_time.wSecond        = time.sec
   local_time.wMilliseconds  = time.usec/1000

   unless Kernel32.setLocalTime(local_time)
     raise "Could not set local time to #{time}."
   end
end