[systemd-devel] generators and service symlink

[Frederic Crozat]

Le mercredi 24 août 2011 à 13:42 +0200, Frederic Crozat a écrit :
> Le mardi 23 août 2011 à 17:56 +0200, Lennart Poettering a écrit :
> > On Mon, 22.08.11 17:52, Frederic Crozat (fcrozat at suse.com) wrote:
> > 
> > > Hi,
> > > 
> > > I'm testing a systemd-generator to create default.target symlink,
> > > depending on /etc/inittab content.
> > > 
> > > Generator is working fine, creating symlink in /run/systemd/generator
> > > but systemd isn't noticing the file (it is still using default.target
> > > from /lib/systemd/system/ ) until systemctl daemon-reload is started.
> > > 
> > > Sounds like a bug but I'm not sure where it is..
> > 
> > Hmm, I am a bit confused. A reload of systemd will cause the generators
> > to be run, so yupp, they should be applied in that case.
> > 
> > Maybe your generator does not work properly during the early boot phase
> > since it requires file systems or services which aren't around yet?
> > 
> > Generators are executed very very early, and can only access data from
> > the root fs, not even /usr. Hence writing them in anything but C is not
> > really an option.
> 
> After digging further, I found the issue :
> - generators was not at fault
> - unlike what I was thinking, /run/systemd/generator doesn't take
> precedence over /lib, so it couldn't work
> - but /run/systemd/system is supposed to take precedence over everything
> (/lib and /etc).
> 
> I've adapted my generator to only create the file in /run/systemd/system
> if there was none in /etc/systemd/system.
> 
> It didn't work as expected due to a bug in
> path-lookup.c:lookup_paths_init which remove from the lookup path lists
> empty directories : therefore /run/systemd/system was evicted from the
> directory list to monitor and wasn't used at all.
> 
> This was added by commit a9dd208208e672a4fe5a3c2405946c1506e034db and it
> should be reverted.

To be more precise, attached part should be committed (only revert one
part of the commit).

-- 
Frederic Crozat <fcrozat at suse.com>
SUSE