[PATCH 1/3] Detect GDB is in cygwin

[Christopher Faylor]

On Thu, Aug 08, 2013 at 03:23:39PM +0800, Yao Qi wrote:
>On 08/08/2013 01:11 PM, Christopher Faylor wrote:
>> If you're just going to always set to unbuffered when something
>> is a pipe, why not just check for a pipe using GetFileType?  Then
>> you don't have to try to use an undocumented Cygwin behaviour.
>
>What I am going to do is to set stdout/stderr unbuffered if we can
>detect that GDB is running in cygwin, with tty allocated or without tty
>allocated.  We'd like to restrict this behaviour change only when
>mingw gdb is running in cygwin.  We don't want to change the behaviour
>on native windows, so we have to rely on this Cygwin behaviour.

You've already acknowledged that your code will decide to become
unbuffered whether you are running on a cygwin pipe or cygwin pty.  What
is special about cygwin pipes that makes you want to make them
unbuffered while ignoring normal Windows pipes?

Can you explain *why* you don't want to change the behavior on native
windows?

I really don't like having gdb rely on undocumented Cygwin behavior.
You're introducing a tenuous dependency between the way Cygwin creates
ptys and pipes which could easily break if we decide to change something
in Cygwin.

cgf