pty issue causes 'screen' to hang when run from mintty as detached

Larry Hall (Cygwin) reply-to-list-only-lh@cygwin.com
Fri Jun 14 03:08:00 GMT 2013


On 6/13/2013 7:39 PM, gmt@malth.us wrote:
> On Thu, 13 Jun 2013, at 14:07, Larry Hall (Cygwin) thusly quipped:
>
>> On 6/13/2013 3:34 PM, Greg Turner wrote:
>>> On Wed, Jun 12, 2013 at 3:19 PM, Matt D. <matt@codespunk.com> wrote:
>>>> "the Windows console window you get through cygstart is not [a pty]"
>>>
>>> Ah, so /that's/ what I recently read uncomprehendingly!  Thanks for
>>> tracking down this concise explanation.  Assuming that's right, then,
>>> I wonder: what is it?
>>
>> What is what?  This Windows console?  It's... well, it's a... um, it's a
> Windows
>> console! ;-)
>>
>> But seriously, it's just something different that doesn't conform to the
>> definition of a PTY.  Windows doesn't have PTYs.  It uses the console
> instead.
>
> So, no win32-console-specific fhandler exists, and clones of the win32 stdio
> handles are simply passed through cygwin core to newlib and vice-versa
> without any funny-business?

I don't really grok what you mean by "funny-business"  But let me say
this.  Cygwin knows how to communicate with Windows consoles.  The code
is in fhandler_console.cc if you want to look at it.  But there is a
mismatch in capabilities and expectations between ptys and the Windows
console API.  That's why there is also fhandler_tty.cc.  The former does
its best to match the Linux/Unix world's expectations to what the Windows
console can provide (which is pretty limited).  The latter simply sidesteps
the console and provides better pty support.

-- 
Larry

_____________________________________________________________________

A: Yes.
 > Q: Are you sure?
 >> A: Because it reverses the logical flow of conversation.
 >>> Q: Why is top posting annoying in email?

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