Re: [libseccomp-discuss] allowing select() fails in i686

[Nikos M. <nm...@re...>]

----- Original Message -----
> On Tuesday, January 27, 2015 04:45:52 PM Nikos Mavrogiannopoulos wrote:
> > Hello,
> >  The attached program as far as I understand creates a filter which
> > allows select(). That works well on my x86-64:
> > $ gcc test.c -lseccomp;./a.out
> > all ok
> > 
> > However, if I run the same thing under i686 emulation, I have:
> > $ gcc -m32 test.c -lseccomp;./a.out
> > select is blocked!
> 
> Since you are running on an x86_64 system, you probably want to explicitly
> add
> support for the x86 ABI if you are interested in creating a filter that works
> on both x86_64 and x86.  This is probably not strictly necessary if you are
> certain that you are linking to a properly build native x86 library, but I
> can't be certain based on what you've posted.

Yes, I'm linking using the Fedora's i686 library. I should have mentioned that this is a reproducer for an issue reported to me:
http://lists.infradead.org/pipermail/openconnect-devel/2015-January/002640.html
I have no i686 available to me, that's why I reproduce that way.

> > Note that allow others calls (e.g., write) are properly executed as
> > expected.
> Have you verified this via strace, or similar? 

I see the output on my screen so write worked :) Running it with strace shows the expected result.

> Without digging to deeply, it
> looks like you test select() before you test write(); if select() fails
> you'll never know if write() worked correctly or not.

Since I see output in my screen, I believe that write worked as expected.

regards,
Nikos