Do not record empty memberUid within mixedgroups

Description

I'm using fusiondirectory 1.3 through Debian package (locally recompiled for buster). I'm using the mixedgroups plugin.

When I create a mixedgroup with one user and several (sub-)groups, I got an error about duplicate (empty) memberUid. Indeed, this is due to the fact that the plugin gets a 'uid' attribute for all its entries, even for (sub-)groups that do not have 'uid' attribute.

I fixed this locally with this patch: In ogroups/mixedgroups/class_mixedGroup.inc, in prepare_save(), I replace:

    foreach ($members as $dn) {
      $ldap->cat($dn, array('uid'));
      $attrs = $ldap->fetch();
      $memberUid[] = $attrs['uid'][0];
    }

by

    foreach ($members as $dn) {
      $ldap->cat($dn, array('uid'));
      $attrs = $ldap->fetch();
      /* Some members (other groups) do not have uid
       * Adding a empty uid is not a problem, but adding two or more is */
      if ($attrs['uid'][0] != '') {
        $memberUid[] = $attrs['uid'][0];
      }
    }

Note: it solve my problem but you might want to do other things, for example:

• allows empty uid but skip entries with no uid attribute (my patch does the same thing for both cases)

• check that there are no duplicate uid (empty or not). If there are:

  • return an error
  • cleanup the list to keep only unique values
  • or ...

  Regards Vincent

PS: the code in gitlab seems to be the same in the 1.4 branch, so this bug does not seem already fixed.