On Wed, 1 Sep 2021 10:46:24 +0200
Corinna Vinschen wrote:
> On Sep  1 17:23, Takashi Yano wrote:
> > On Wed, 1 Sep 2021 10:07:48 +0200
> > Corinna Vinschen wrote:
> > > On Sep  1 09:16, Takashi Yano wrote:
> > > > On Wed, 1 Sep 2021 08:02:20 +0900
> > > > Takashi Yano wrote:
> > > > > On Tue, 31 Aug 2021 17:50:14 +0200
> > > > > Corinna Vinschen wrote:
> > > > > > So for the time being I suggest the below patch on top of topic/pipe.
> > > > > > It contains everything we discussed so far.
> > > > > 
> > > > > One more thing. 'git log' cannot stop normally with 'q' with your patch.
> > > > 
> > > > The same happes with 'yes |less'.
> > > > 
> > > > The cause is that write side cannot detect closing read side because
> > > > query_hdl (read handle) is still opened.
> > > 
> > > Oh
> > > 
> > > my
> > > 
> > > god.
> > > 
> > > 
> > > That kills the entire idea of keeping the read handle :(
> > 
> > One idea is:
> > 
> > Count read handle and write handle opned using NtQueryObject().
> > If the numbers of opened handle are equal each other, only
> > the write side (pair of write handle and query_hdl) is alive.
> > In this case, write() returns error.
> > If read side is alive, number of read handles is greater than
> > number of write handles. 
> 
> Interesting idea.  But where do you do the count?  The event object
> will not get signalled, so WFMO will not return when performing a
> blocking write.

I imagined something like attached patch.

Unfortunately, the attached patch seems to have bug that
occasionally causes the following error while building
cygwin1.dll.

<command-line>: error: "GCC_VERSION" redefined [-Werror]
<command-line>: note: this is the location of the previous definition
cc1plus: all warnings being treated as errors
make[1]: *** [Makefile:1942: fhandler_proc.o] Error 1

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