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

[Mark Hatle <mark.hatle@windriver.com>]

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.

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.

--Mark

>  		# Gather special src/first package data
>  		if srcname == splitname:
>  			srcrdepends    = splitrdepends
> 
> 
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