Date: Thu, 20 Aug 2009 10:39:41 -0400
From: Christopher Faylor <cgf-use-the-mailinglist-please@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: [ANNOUNCEMENT] Updated: run-1.1.11-1
Message-ID: <20090820143940.GA13570@ednor.casa.cgf.cx>
Reply-To: cygwin@cygwin.com
Mail-Followup-To: cygwin@cygwin.com
References: <200908171705.n7HH5TYe024203@StraightRunning.com>  <4A89A490.1050108@cwilson.fastmail.fm>  <4A8D429A.1070306@byu.net>  <4A8D4B6A.9080706@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4A8D4B6A.9080706@gmail.com>
User-Agent: Mutt/1.5.20 (2009-06-14)
Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm
Precedence: bulk
Sender: cygwin-owner@cygwin.com
Mail-Followup-To: cygwin@cygwin.com

On Thu, Aug 20, 2009 at 02:11:06PM +0100, Dave Korn wrote:
>Eric Blake wrote:
>
>> See this thread on the gnulib list, which claims that you can use this
>> undocumented snippet to decide whether a HANDLE is a console:
>> 
>>> #define IsHandleConsole(h) (((long) (h) & 3) == 3)
>> 
>> http://lists.gnu.org/archive/html/bug-gnulib/2009-08/msg00065.html
>
>  I wouldn't rely on that for a microsecond.  The low two bits of a HANDLE are
>pretty free form and could easily be used for other purposes by other types of
>object.  Read the rest of the thread; it's a convention used internally by
>WINE.  MS doesn't necessarily follow suit.  See also Chen on handles:
>
>http://blogs.msdn.com/oldnewthing/archive/2005/01/21/358109.aspx

Is there something wrong with Cygwin's code for determining if a handle is a
console?

  ...
  if (GetConsoleScreenBufferInfo (handle, &buf))
    {
      ...
    }
  else if (GetNumberOfConsoleInputEvents (handle, (DWORD *) &buf))
    {
      ...
    }

It's been working pretty well for centuries.

cgf

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple