[chiark.chat] Re: RFH: sysvinit etc. in Debian

[Andreas Messer]

On Thu, Nov 08, 2018 at 08:20:33PM +0000, Ian Jackson wrote:
> Lorenz writes ("Re: [chiark.chat] Re: RFH: sysvinit etc. in Debian"):
> > * libelogind-dev is conflicting with libsystemd-dev (the man pages); I have no
> > idea on how a Debian build machine work, but package like polkit-1 in Debian
> > will        need both, can a build machine deal with 2 conflicting build
> > depends?
> 
> Won't polkit-1 in Debian build just fine against the libsystemd-dev
> that is there, and then work with elogind ?  We don't need to modify
> polkit-1 in Debian, do we ?

No it wont. The function interface is identical, but there is magic in
the libraries itself. When analyzing systemd-logind and elogind I figured
out, that not all library calls result in dbus actions. Many library
functions have implicit knowledge about the the structure and work
without even talking to *logind through dbus. The most problematic
one: systemd-logind and elogind use cgroups to assign a process to a
session. Unfortunately, both of them use a different cgroup structure.
So when an application uses a libsystemd/libelogind interface which
directly or even indirectly derives session information for the calling
application, then either library will analyze the cgroup of the process
and derive the session from it. But since they use different structure
an application linked with libsystemd will never get the proper session
when elogind is used and vice versa. Therefore we had to create two
different polkit variants. 

This was at least the case a year ago when i was making the package. I 
don't know if that has changed in the meanwhile.

cheers,

Andreas
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