Re: [PATCH] Ignore "yes: standard output: Broken pipe" errors

[Jan Kara <jack@suse.cz>]

On Wed 26-07-17 18:22:21, Eryu Guan wrote:
> On Wed, Jul 26, 2017 at 10:22:13AM +0200, Jan Kara wrote:
> > On Wed 26-07-17 15:47:19, Eryu Guan wrote:
> > > On Tue, Jul 25, 2017 at 04:33:20PM +0200, Jan Kara wrote:
> > > > Recently, some tests started failing because they had
> > > > 
> > > > yes: standard output: Broken pipe
> > > > 
> > > > in their output. Fix the problem by discarding errors from yes(1)
> > > > program.
> > > > 
> > > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > > ---
> > > >  common/rc         | 12 ++++++------
> > > >  tests/generic/081 |  2 +-
> > > >  tests/generic/108 |  2 +-
> > > >  3 files changed, 8 insertions(+), 8 deletions(-)
> > > 
> > > I'm wondering which case failed for you and what's the diff output and
> > > .full file? And what change caused the failure for you? Because I didn't
> > > see any failure on my RHEL7 box nor Fedora rawhide box. I compiled
> > > latest yes from coreutils git repo and didn't hit the error either.
> > > 
> > > So I suspect that it might be other commands in the pipeline that failed
> > > and caused the broken pipe.
> > 
> > I've started seeing failures after I've updated the testing VM to openSUSE
> > Leap 42.2. And yes(1) failing with this error is "normal" if SIGPIPE is
> > ignored - just try ( trap "" PIPE; yes | exit; ) and observe the error.
> > So it is just that in the new VM something makes yes(1) ignore SIGPIPE and
> > honestly I'm not sure what that is even though I've looked for a while. But
> > regardless of that, ignoring stderr from yes(1) seems like a safe thing to
> > do.
> 
> Ahh, I see the problem. Actually Eric Biggers has fixed a very similar
> problem in commit 9bcb266cd778 ("generic/397: be compatible with ignored
> SIGPIPE"), but at that time he only saw generic/397 failure, so he
> decided to fix that test only.
> 
> How about print out warnings and exit if check finds SIGPIPE is ignored?
> Because seems we can't un-ignore it in a sub-shell, if it's already
> ignored on start. e.g.
> 
> if trap -p | grep -q "'' SIGPIPE"; then
> 	echo "SIGPIPE is ignored by current shell, this will cause unexpected"
> 	echo "broken pipe error in tests. Please unignore SIGPIPE and rerun."
> 	echo "For bash, just run 'trap - SIGPIPE'"
> 	exit
> fi
> 
> Because I think ignoring SIGPIPE indicates bugs/issues somewhere, as the
> python bug mentioned in comment 9bcb266cd778.

OK, fair enough.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR