[PATCH] Cygwin: pty: Introduce disable_pcon in environment CYGWIN.

[Takashi Yano]

Hi Corinna,

On Mon, 20 Jan 2020 11:06:46 +0100
Corinna Vinschen wrote:
> On Jan 20 11:50, Takashi Yano wrote:
> > - For programs which does not work properly with pseudo console,
> >   disable_pcon in environment CYGWIN is introduced. If disable_pcon
> >   is set, pseudo console support is disabled.
> Oh well, do we really need that?

This is, for example, needed to solve the issue reported in
https://www.cygwin.com/ml/cygwin/2020-01/msg00147.html.

I looked into this problem, and found that cgdb read output of
gdb from pty master and write it to ncurses. The output from
pty master includes a lot of escape sequences which are generated
by pseudo console, however, ncurses does not pass-through them
and shows garbages. This is the cause of that issue.

cgdb is the only program do such things so far, however, there
may be more programs which do not expect escape sequences read
from pty.

There is no way to control pseudo console not to generate
escape sequences, therefore, I proposed this patch.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>