[buildd-tools-devel] Bug#797781: diffoscope does not seem to work with schroot]

[Aurelien Jarno]

On 2015-09-02 14:28, Santiago Vila wrote:
> Hello.
> 
> I've just reassigned this report to schroot.
> 
> Below is the reason.
> 
> Thanks.
> 
> ----- Forwarded message from Mattia Rizzolo <mattia at mapreri.org> -----
> 
> Date: Wed, 2 Sep 2015 14:08:42 +0000
> From: Mattia Rizzolo <mattia at mapreri.org>
> To: Santiago Vila <sanvila at debian.org>, 797781 at bugs.debian.org
> Subject: [Reproducible-builds] Bug#797781: Bug#797781: diffoscope does not seem to work with schroot
> User-Agent: Every email client sucks, this one just sucks less.
> 
> On Wed, Sep 02, 2015 at 01:41:23PM +0000, Santiago Vila wrote:
> > Package: diffoscope
> > Version: 31
> > 
> > Greetings. I'm running jessie with several chroots created with
> > schroot. As a normal user, I do this:
> > 
> > schroot -c sid
> > diffoscope some.deb someother.deb
> > 
> > and this is the result:
> > 
> > CRITICAL /dev/shm is not available or not on a tmpfs. Unable to create semaphore.
> > 
> > I believe such error is not supposed to happen.
> 
> Well, quite a lot of stuff requires shm nowadays.
> 
> Consider that we rb people run diffoscope inside scrhoot, and it just
> works.  We have
> 
>     /dev/shm    /dev/shm    none    rw,bind     0   0
> 
> in /etc/schroot/default/fstab.
> 
> 
> Personally I'd not consider this a diffoscope bug.

The buildd flavour of the configuration mount a tmpfs in /dev/shm. AFAIK
this is not done for the default flavour as too options are possible
there:
- Bind mount like above. This means sharing the shm directory with the
  outside world. This might have some security implications, and
  unwanted consequences.
- Empty tmpfs like for buildds. This means the processes do not have
  accesses to shared memory from processes outside of the chroot.

Depending on how the user want to use schroot, one or the other
configuration should be used. I don't know how we should choose the
default one.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien at aurel32.net                 http://www.aurel32.net