3.2.0-1: possible regression Cygwin DDL bug (W10) when using multiple pipes

[Takashi Yano]

On Wed, 28 Apr 2021 22:17:44 +0200
M2 via Cygwin <cygwin@cygwin.com> wrote:
> On 28/04/2021 16:36, Takashi Yano wrote:
> > On Wed, 28 Apr 2021 15:38:13 +0200
> > M2 via Cygwin <cygwin@cygwin.com> wrote:
> >> Hi,
> >> I found a possible regression issue between cygwin 3.1.7-1 and 3.2.0-1.
> >>
> >> The issue happens with "short" output in multiple piping, such as the following example:
> >>
> >>      dir | grep c | sed "s/^/foo/" | sed "s/oo/OO/"
> >>
> >> (the case I run is different, but the bug is exposed by something silly/simple as this)
> >>
> >>
> >> In 3.1.7, all is fine and you get what you expect.
> >>
> >> In 3.2.0, 3 out of 4 executions hang: the last command on the pipeline (i.e. `sed "s/oo/OO/"`)
> >> hangs forever, while all preceding commands (i.e. both `grep c` and `sed "s/^/foo/"`) terminate correctly.
> >>
> >> Attached, cygcheck outputs for both 3.1.7 and 3.2.0
> > I cannot reproduce your problem.
> >
> > In 64 bit cygwin:
> >
> > ...
> >
> > In 32 bit cygwin:
> > ...
> >
> Some clarification: I run a mixed configuration with Cygwin commands 
> mostly ran in CMD.EXE shell.
> 
> In my installation it seems that output from a WINDOWS console program 
> causes trouble when piped to a CYGWIN process.
> 
> Close repetition such as loops tend to cause the bug.
> 
> 
> Consider the following cases. I have CYGWIN\BIN in my (CMD) PATH, and 
> drive prefix set to "/"
> 
> Case 1: BASH shell - all CYGWIN commands - WORKS
> 
>   for i in {1..20} ; do ls -la | grep . | sed s/./foo/ | sed s/oo/OO/ ; done
> 
> 
> Case 2: BASH shell - first command is a WINDOWS command - WORKS
> 
>   for i in {1..20} ; do /c/windows/system32/ipconfig.exe /all | grep . | 
> sed s/./foo/ | sed s/oo/OO/ ; done
> 
> 
> Case 3: CMD shell - all CYGWIN commands - WORKS
> 
>   for /l %i in (1,1,20) do ls -la | grep . | sed s/./foo/ | sed s/oo/OO/
> 
> 
> Case 4: CMD shell - first command is a WINDOWS command - HANGS 50% of times
> 
>   for /l %i in (1,1,20) do ipconfig.exe /all | grep . | sed s/./foo/ | 
> sed s/oo/OO/

I got it. Could you please try the latest cygwin snapshot?
https://cygwin.com/snapshots/

Thanks.

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