Re: [PATCH 5/5] update-alternatives: Add alternatives as a runtime provide

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Wed, 2011-08-03 at 11:03 -0500, Mark Hatle wrote:
> On 8/3/11 10:40 AM, Richard Purdie wrote:
> > On Wed, 2011-08-03 at 09:41 -0500, Mark Hatle wrote:
> >> On 8/3/11 7:20 AM, Richard Purdie wrote:
> >>> On Tue, 2011-08-02 at 09:49 -0500, Mark Hatle wrote:
> >>>> On 8/2/11 8:46 AM, Phil Blundell wrote:
> >>>>> On Mon, 2011-08-01 at 19:17 -0500, Mark Hatle wrote:
> >>>>>> The following allows RPM to generate the SDK image, however without it
> >>>>>> we get a failure because the system has nothing that provides /bin/sh.
> >>>>>>
> >>>>>> Unfortunately the patch causes failures with ipk and deb packages because
> >>>>>> they can not have filenames within their RPROVIDES.  I'm looking for some
> >>>>>> type of a resolution to the issue, the only thing I can think of is to
> >>>>>> add a way to manually add a FILERPROVIDE for the items.  This will require
> >>>>>> changes to the way FILERPROVIDE is currently generated... but I'm not sure
> >>>>>> how we can automatically generate the FILERPROVIDE values without the use of
> >>>>>> python...
> >>>>>>
> >>>>>> Any suggestions?
> >>>>>
> >>>>> It's never really been the intent that update-alternatives should put
> >>>>> the name of the link being provided into RPROVIDES.  If you want to
> >>>>> solve the specific problem with /bin/sh then just adding RPROVIDES_${PN}
> >>>>> += "virtual-bourne-shell" or something to bash and busybox is probably
> >>>>> the easiest way of doing that.
> >>>>>
> >>>>> I wouldn't be entirely opposed to the concept of what you're proposing
> >>>>> here, though.  Something like:
> >>>>>
> >>>>> RPROVIDES_${PN} += "${@' '.join(map(lambda x:
> >>>>> legitimize_package_name("virtual-path-" + x), filter(lambda x: x != '',
> >>>>> [ d.getVar('ALTERNATIVE_LINK', True) or '' ] +
> >>>>> (d.getVar('ALTERNATIVE_LINKS', True) or '').split())))}"
> >>>>>
> >>>>> might be what you want, perhaps.  I'm not sure that the resulting
> >>>>> virtual names will be very pretty though.
> >>>>
> >>>> Hmm.. Coming from the RPM world, the virtual-path- because we can't just
> >>>> "provide" a file in the system seems a bit wonky to me.  But it should be able
> >>>> to work.  For RPM at least, we'd want a reversing function to turn virtual paths
> >>>> back into real paths.
> >>>>
> >>>> If I have time today, I'll try to implement a proof of concept and see if I can
> >>>> get it to work reasonably well.
> >>>
> >>> Just to be clear for Phil's benefit, RPM natively supports file based
> >>> dependencies, so a dependency of "/bin/sh" is automatically fulfilled by
> >>> a package which contains "/bin/sh". Some dependencies such as the
> >>> shebang in scripts are automatically added to packages and resolved by
> >>> rpm.
> >>>
> >>> I did chase down this bug a bit and it seems that if you "bitbake
> >>> meta-toolchain-game" you hit an error about /bin/sh being missing but if
> >>> you "bitbake busybox; bitbake meta-toolchain-gmae" it will work. This is
> >>> due to busybox shipping a /bin/sh.
> >>>
> >>> The question is therefore how to handle this on the deb/ipk side and
> >>> ensure we get consistency between the behaviours of the different
> >>> backends. I thought with the rpm filedeps code in do_package, we were
> >>> adding things like /bin/sh dependencies to the other package formats but
> >>> now I'm not so sure. 
> >>
> >> Due to deb/ipk not handling file based dependencies, they are filtered out on
> >> the creation of the deb/ipk packages.  The original intention was to use them,
> >> but it wasn't possible at the time.  Simply adding a ton of file-based
> >> dependencies seemed like a huge mistake as well.  (We'd have to add virtual
> >> provides for all of the virtual requirements....)
> >>
> >> We could certainly select a few specific requirements and scan for and use those
> >> to catch obvious issues, such as perl, sh, bash, env/python... but it's still
> >> only a partial solution to the real issue.
> > 
> > Short term I'm tempted to buy us some time and do this (rpm specific):
> > 
> > package_rpm: Ensure alternatives links are reflected in rpm package dependencies
> > 
> > Currently, if a file is provided as an alternative link within the package, rpm
> > doesn't see the dependency. This works out badly for dependencies such as /bin/sh
> > which scripts might require.
> > 
> > Since rpm detects and adds these dependencies we do need to ensure the dependency
> > information in the packages is correct. This patch does so for the rpm backend
> > ensuring internal consistency whilst the approach for addressing this problem in
> > the other package backends is considered.
> > 
> > Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
> > ---
> > diff --git a/meta/classes/package_rpm.bbclass b/meta/classes/package_rpm.bbclass
> > index abedc68..c44fdcc 100644
> > --- a/meta/classes/package_rpm.bbclass
> > +++ b/meta/classes/package_rpm.bbclass
> > @@ -501,6 +501,10 @@ python write_specfile () {
> >  		splitrconflicts  = bb.data.getVar('RCONFLICTS', localdata, True) or ""
> >  		splitrobsoletes  = []
> >  
> > +		# For now we need to manually supplement RPROVIDES with any update-alternatives links
> > +		if pkg == d.getVar("PN", True):
> > +			splitrprovides = splitrprovides + (d.getVar('ALTERNATIVE_LINK', True) or '') + (d.getVar('ALTERNATIVE_LINKS', True) or '')
> > +
> 
> Will the "+" add a space in this case, otherwise we need additional spaces added.

It needs more spaces. I realised that after I posted it.

> But this is a good solution to the issue.  It's RPM specific (for now) until we
> decide if we have to address the other packaging systems.

I think I'll likely merge this to fix the immediate issues and we can
think about better solutions to this...

Cheers,

Richard