[PATCH] fix for pipe() on sparc

[Rich Felker]

On Wed, Aug 20, 2014 at 05:50:08PM +0200, Waldemar Brodkorb wrote:
> Hi Rich,
> Rich Felker wrote,
> 
> > On Wed, Aug 20, 2014 at 10:10:30AM +0200, Bernhard Reutner-Fischer wrote:
> > > On 19 August 2014 21:11, Waldemar Brodkorb <wbx at openadk.org> wrote:
> > > > When using something like this:
> > > >  $ echo foo|grep foo|wc -l
> > > > with mksh shell, you get an runtime error.
> > > >
> > > > Glibc and klibc does not do these extra check.
> > > > After removing this check using double pipes work fine.
> > > > Tested with Qemu 2.1.0.
> > > 
> > > Applied, thanks!
> > 
> > Is there any explanation for what the patch does and why it's correct?
> > I suspect it is, but it would be nice to see (in both the patch
> > proposal and the commit message) an indication of why the change is
> > deemed correct rather than just "problem symptom observed before, goes
> > away after patch".
>  
> Sorry, I wanted to add the original author to CC, but have forgotten
> it. I can not add any more explanation to the problem. I have done
> my best to produce a simple testcase and to run the perl based mksh
> testsuite in Qemu and provide Thorsten a backtrace, some
> disassembly and a static binary, as I know he has access to some
> real sparc hardware.
> He analyzed it and suggested this change and I tested it again and
> was happy that my system now boots up fine without issues.
> At this point I just could had kept the change for myself.
> But I think better we have a fix for the problem. I don't know exactly why
> the code was added. In a perfect world the programmer had added some
> comments while adding assembly code, which usage might not be
> obvious for skilled people like you.

No problem. As far as I can tell, the new version is equivalent to
what's in glibc now, and despite the old version supposedly being
copied from glibc, I can't find it in the glibc history. I am
interested in what the incorrect check was doing though, and why it
was wrong.

Rich