[oe] Problem with dependencies in packages

[Graham Gower]

On 14 February 2011 10:59, Graham Gower <graham.gower at gmail.com> wrote:
> On 14 February 2011 09:20, Filip Zyzniewski <filip.zyzniewski at gmail.com> wrote:
>> Hi,
>>
>> I think I have found a problem with versioned dependencies (or I don't
>> unserstand something).
>>
>> I am trying to switch the jlime distribution from ipk to deb packages.
>> When debugging do_rootfs problems I stumbled upon this:
>>
>> The following packages have unmet dependencies:
>>  libncursesw5: Depends: libtinfo5 (>= 5.7+20110115) but 5.7-r16 is to
>> be installed
>> E: Broken packages
>>
>> The Depends line in deb package control file comes from
>> classes/package_deb.bbclass:do_package_deb():
>>
>> rdepends = explode_deps(unicode(bb.data.getVar("RDEPENDS", localdata, 1) or ""))
>> [...]
>> ctrlfile.write(u"Depends: %s\n" % ", ".join(rdepends))
>>
>>
>> The dependency string comes from classes/package.bbclass:766:
>> dep = "%s (>= %s)" % (dep_pkg, ver_needed)
>>
>> ver_needed comes (in case of ncurses) from .ver files in the build
>> tree, generated by the same function a bit earlier using pkgver
>> variable set in lines 657-661:
>>
>>                pkgver = bb.data.getVar('PKGV_' + pkg, d, True)
>>                if not pkgver:
>>                        pkgver = bb.data.getVar('PV_' + pkg, d, True)
>>                if not pkgver:
>>                        pkgver = ver
>>
>> and in ncurses_5.7.bb we have:
>>
>> PATCHDATE = "20110115"
>> PKGV = "${PV}+${PATCHDATE}"
>>
>>
>> Isn't this an incosistency that ncurses_5.7-r16 depends on
>> libtinfo5_5.7+20110115 ? Shouldn't it depend on libtinfo5_5.7-r16?
>
> Probably.
>
>> What's the reason for this situation? Does opkg somehow compare these
>> versions in another way causing the problem to be invisible?
>
> Opkg uses the same version comparison as dpkg. In fact, the
> verrevcmp() code in opkg was copied verbatim from dpkg. The ascii
> values of '+' and '-' are compared, with '+' being lower than '-'.
>
> # opkg compare-versions 5.7-r16 ">=" 5.7+20110115
> # echo $?
> 0

I think I may have just confused the issue with misinformation...

The hyphen is used as a delimiter between the version and the revision.
http://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version

So the +date is part of the version, not the revision. Both opkg and
dpkg compare the versions and only if they are the same, the revisions
are compared (with the same verrevcmp function).

Furthermore, I assumed that a return code of 0 from opkg
compare-versions meant the comparison was true (like most success
return codes from applications). This is not the case.

# opkg compare-versions 1 ">=" 2 ; echo $?
0
# opkg compare-versions 2 ">=" 1 ; echo $?
1

> So, 5.7-r16 would be expected to satisfy the dependency in this case.
> I am unsure why the version comparison fails for you... maybe the dpkg
> comparison code has been changed since it was copied into ipkg?
>

In fact the dependency shouldn't be satisfied here. Opkg should fail
the same way as dpkg is failing.

-Graham