[Pkg-samba-maint] Bug#1021371: gnome-control-center doesn't start, saying libsamdb-common.so.0 requires version `LDB_2.2.4'

[Michael Tokarev]

Control: tag -1 + confirmed
07.10.2022 11:38, Simon McVittie wrote:
...
> # smbclient --help
> smbclient: /usr/lib/x86_64-linux-gnu/libldb.so.2: version `LDB_2.2.4' not found (required by /usr/lib/x86_64-linux-gnu/samba/libsamdb-common.so.0)
> 
> Workaround: also upgrade samba-libs to the version from testing, or fully
> upgrade to testing.
> 
> Removing the symver LDB_2.2.4 from libldb.so.2 was an ABI break, so libldb2
> should have versioned Breaks against dependent packages that use the old
> symver. It looks as though only the samba and maybe sssd source packages
> will be affected by this.

I talked about this with upstream samba. It is their decision to break old
stuff like this, by dropping intermediate library versions without actually
changing any functions/symbols. I don't know why this is done like that,
from my PoV it is plain wrong.

When I packaged 4.17 version (currently in experimental), I created a patch
which adds missing intermediate versions (added during maintenance of 4.16
series) to 4.17, but later on dropped it. It will be the same with 4.16->
4.17 upgrade.  See
https://salsa.debian.org/samba-team/samba/-/commit/363ec9c9cf107536b94bfd0d5bd623644413b165

In debian samba package, there's a strict versioned dependency of libldb2
for samba package - actually samba-dsdb-modules - the only package which
actually *uses* libldb.  For a bullseye version of samba-dsdb-modules
package, the dependency is

   libldb2 (<< 2:2.2.4~), libldb2 (>= 2:2.2.3-2~deb11u2~)

(so it conflicts even with next minor version of libldb2).

But it looks like other samba packages does have libldb2 dependency.
It looks like I need to take a look at how libldb2 is used by samba-libs,
maybe some libs should be moved between packages.

> Also, when a single source package builds multiple libraries, it's usually
> a lot more robust if the dependencies between those libraries are strict
> (libfoo Depends: libbar (= ${binary:Version}) so that users are forced
> to upgrade either everything or nothing from that source package. This

The only real user of libldb2 in samba is samba-dsdb-modules. And exactly
due to this reason I switched from the ugly "between" version like I
demonstrated above to exact version. libldb2 builds from samba package
since bookworm version (4.16), in bullseye libldb was in its own package.

> is because the upstream developer will never have tested with mismatched
> versions, and code in the same source package often uses private/internal
> interfaces that are not formally part of the API/ABI, or relies on
> internal implementation details that might change in a newer version.

I weren't aware that libldb2 is linked to from samba-libs. Now I do, and
ofc I'll take care of this. Either by adding countless patches adding
missing versions which upstream refuses to add for some unknown reason
like I initially did for 4.17 version, or by rearranging libraries into
different packages so that libldb isn't used by samba-libs, or maybe
upstream will do their part and add those versions itself, I dunno.

Thanks,

/mjt