Re: [bug-gawk] Behavior of fflush with SIGPIPE on stdout [PATCH]

[alexandre.ferrieux]

On 10/03/2017 16:23, Andrew J. Schorr wrote:
> Hi,
>
> Thanks for these bug reports. I think the basic problem is that
> we ignore SIGPIPE and rely upon detecting write errors.
> [...]
>
> I guess the fix is probably to add some logic to issue a fatal error
> when fflush fails, unless the output file is registered as NONFATAL.
> The only question is whether this might break existing code.
>
> A possible patch to the master branch is attached. This will NOT apply
> against 4.1.x. Sorry.

Hi Andy,

Thanks a lot, that's exactly what I hoped for :)

Regarding existing code, please bear in mind that those script that rely on this behavior (1) do it only since 2013 ; 
(2) are incompatible with other awk implementations and (3) depend in a very sensitive manner in stdio buffer sizes, 
since this for a given sequence

        print ...
        print ...
        print ...
        fflush(stdout)

... the precise line where the error bursts will vary depending on buffer 
filling.

Currently (without your patch), the program will randomly exit (error on print) 
or not (error on fflush).
With your patch, the program will reliably exit on any of those lines, 
regardless of the tuning of stdio.

Thanks again and looking forward to downstream integration in my distro ;-)

-Alex

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