[PATCH] Cygwin: pty: Make system_printf() work after closing pty slave.

[Takashi Yano]

On Wed, 20 May 2020 17:46:11 +0900
Takashi Yano via Cygwin-patches <cygwin-patches@cygwin.com> wrote:
> On Tue, 19 May 2020 15:04:24 -0400
> Ken Brown via Cygwin-patches <cygwin-patches@cygwin.com> wrote:
> > Hi Takashi,
> > 
> > On 5/19/2020 7:35 AM, Takashi Yano via Cygwin-patches wrote:
> > > - Current pty cannot show system_printf() output after closing pty
> > >    slave. This patch fixes the issue.
> > 
> > Sorry to be returning the favor so soon, but this patch causes 'make check' in 
> > the texinfo source tree to hang.  I don't have time at the moment to try to 
> > produce a simple test case, so here's a complicated way to reproduce the problem:
> > 
> > 1. Clone the texinfo git repo:
> > 
> >    $ git clone https://git.savannah.gnu.org/git/texinfo.git
> > 
> > 2. Build texinfo:
> > 
> >    $ cd texinfo
> >    $ ./autogen.sh && ./configure # Maybe CFLAGS='-g -O0' for debugging
> >    $ make
> > 
> > 3. Test the standalone info reader:
> > 
> >    $ cd info
> >    $ make check
> > 
> > It hangs while running the test t/malformed-split.sh, leaving a ginfo process 
> > and a pseudotty process running, with ginfo trying to close a pty slave.
> > 
> > Note that this test uses both ptys and fifos, so there's always a chance that 
> > this is another fifo bug.  But reverting your patch fixes the problem, so I 
> > think it's probably a pty bug.
> 
> Sorry for inconvenience. I can reproduce your problem.
> I will check what is happening. Please wait a while. 

I found the cause. If pty master is closed, wait_pcon_fwd()
stucks because pty_master_fwd_thread is not running.

I will submit a patch to fix this issue soon.

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