classic 32 bit application

[Sergio Schvezov]

On Tue, 4 Apr 2017 14:53:17 +0000, Alistair Grant wrote:
> Hi James,
>
> Thanks for your follow-up.
>
> On Tue, Apr 04, 2017 at 06:10:32PM +0800, James Henstridge wrote:
>> On 4 April 2017 at 03:25, Alistair Grant <akgrant0710 at gmail.com> wrote:
>> > Hi James,
>> >
>> > On Fri, Mar 31, 2017 at 03:08:39PM +0800, James Henstridge wrote:
>> >> On 31 March 2017 at 05:38, Seth Arnold 
>> <seth.arnold at canonical.com> wrote:
>> >> > On Thu, Mar 30, 2017 at 08:10:26AM +0200, Alistair Grant wrote:
>> >> >> I'm trying to package a 32 bit software development 
>> environment: Pharo
>> >> >> Smalltalk (http://pharo.org).
>> >> >>
>> >> >> I've got it working OK as a devmode package, but as soon 
>> as I switch it
>> >> >> to classic confinement it fails to run.
>> >> >
>> >> > I was under the impression the usual progression is from devmode to
>> >> > strict. Are you certain classic is the correct direction 
>> for your snap?
>> >>
>> >> I ran into a similar conundrum for the Python snap I built.  If your
>> >> package contains a language runtime and interactive shell, it is
>> >> difficult to decide what sort of confinement policy makes sense.  It
>> >> is possible to run under strict confinement with few or any interfaces
>> >> connected, but depending on what the user wants to do might want a lot
>> >> more permission (e.g. ability to access the network, ability to write
>> >> to the home directory, etc).
>> >>
>> >> At present the best option seems to be to package things with strict
>> >> confinement but ensure that it will be functional if installed with
>> >> --classic.  That gives safety by default, but full functionality on
>> >> request.  Of course, this means snapcraft isn't giving any help with
>> >> the necessary link flags to get things working reliably on non-Ubuntu
>> >> systems.  I guess that's something to try and solve next.
>> >>
>> >> James.
>> >
>> > This is a step closer, but is still problematic as the bin directories
>> > (/bin, /usr/bin, etc.) are still mapped to the snapcraft package.
>> >
>> > Looks like I'll have to wait until the 64 bit version of the
>> > application is available.
>> 
>> If there are particular utilities usually found in /bin or /usr/bin
>> that aren't part of the "core" snap, you will probably need to include
>> them in your own snap.  If you still want help with this, it'd be
>> useful to give a link to your in-progress snap or snapcraft project.
>> Without that, it is a bit difficult to tell what is causing the
>> problem.
>
> OK, thanks for the clarification.
>
> The real problem is that I'm unable to get a 32 bit application working
> with classic confinement.
>
> The application runs fine in devmode, but building with classic
> confinement and running produces:
>
> $ pharo --version
> /snap/pharo/x1/usr/bin/pharo: line 13: 
> /snap/pharo/x1/usr/bin/pharo-vm/pharo: No such file or directory
> $ ls -l /snap/pharo/x1/usr/bin/pharo-vm/pharo
> -rwxr-xr-x 1 root root 4599008 Apr  4 15:15 
> /snap/pharo/x1/usr/bin/pharo-vm/pharo
> $ snap run --shell pharo
> $ ldd /snap/pharo/x1/usr/bin/pharo-vm/pharo
> 	not a dynamic executable
>
> My guess is that I've either configured it incorrectly, or for some
> reason the 32 bit architecture isn't working in classic confinement.

I am not sure how the low levels work here wrt to program loaders and 32bit versus 64bit support, if they are different, there is currently no support in snapcraft for this, which for classic confined snaps sets the program loader to a specific binary, you can of course override this with a combination of LDFLAGS to set the loader to something more appropriate (just make sure the loader comes from the core snap or you won't be cross distro or even cross series on Ubuntu).

> The project is at: https://github.com/akgrant43/pharo-snap
> I'm just changing the confinement to classic to reproduce the problems.

You can't just switch the confinement value, you will need to rebuild.

> (A bit of a disclaimer, this is my first snapcraft project and I'm not
> familiar with the pharo build process, so the whole thing is still a
> work-in-progress, and needs plenty of tidying up :-)).

When going classic you might need more knowledge of how everything is connected and linked though. Even with a code base I know I ran into things like this https://forum.snapcraft.io/t/classic-snaps-and-python/141

-- 
Sent using Dekko from my Ubuntu device