Re: [Quilt-dev] workaround "received broken pipe signal" bash bug (was [patch 2/8])

[Gary V. Vaughan]

John Vandenberg wrote:
> On 9/14/05, address@hidden <address@hidden> wrote:
>
> > Unless compiled specially just to avoid it, bash gives an occasional
> > disconcerting (but spurious) warning when a process at the receiving
> > side of a shell pipe closes before the sender has flushed all of its
> > data.  `quilt refresh' is particularly prone.
> >
> > This patch simply redirects stderr to /dev/null in the one instance
> > that seems to be the root of the problem, and thus saves the bother
> > of recompiling bash.
>
>
> Gary,
>
> I haven't noticed this problem on OS X 10.3.2, using bash 2.05b.0(1). 
> If I understand correctly, the following simple case should
> demonstrate the problem?
>
> $ (echo foo; i=1; for ((i = 0; i < 100; i++)); do sleep 1; done) | awk
> '{ exit }'

Nope, this doesn't error out on Apple's bash.

This does (I think there needs to be a separate long running non-shell
process generating the output):

$ cvs diff | (exit 1)

> If not, could you provide a more complicated case that does cause
> report the error, as I would like to see the problem here, or know
> what is different.

There is a compile time option to bash (DONT_REPORT_SIGPIPE) which
turns off the error message, but it is not part of the default build,
so many vendor supplied and self built bash installations exhibit the
problem.

> If there is such a fundamental problem with bash on 10.4.2, a
> configure test to reject that build of bash would be a simpler fix.

It's not just Apple's bash :-(  Here is a different workaround that
might be less contentious (my mailer will almost certainly wrap long
lines, so you'll need to apply by hand):

Index: quilt-HEAD/scripts/patchfns.in
===================================================================
--- quilt-HEAD.orig/scripts/patchfns.in
+++ quilt-HEAD/scripts/patchfns.in
@@ -607,7 +607,8 @@ patch_header()
 {
        @AWK@ '
        $1 == "***" || $1 == "---" \
-               { exit }
+               { stop=1 }
+       stop    { next }
        /^Index:[ \t]|^diff[ \t]|^==*$|^RCS file: |^retrieving revision 
[0-9]+(\.[0-9]+)*$/ \
                { eat = eat $0 "\n"
                  next }

Cheers,
        Gary.
--
Gary V. Vaughan      ())_.  address@hidden,gnu.org}
Research Scientist   ( '/   http://tkd.kicks-ass.net
GNU Hacker           / )=   http://www.gnu.org/software/libtool
Technical Author   `(_~)_   http://sources.redhat.com/autobook

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