Date: Thu, 20 Aug 2009 10:39:41 -0400
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
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Subject: Re: [ANNOUNCEMENT] Updated: run-1.1.11-1
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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

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