[systemd-devel] Is there a reason to forcefully create /etc/mtab?

[Leonid Isaev]

On Sun, Jul 06, 2014 at 09:15:28PM +0400, Ivan Shapovalov wrote:
> On Sunday 06 July 2014 at 13:13:55, Mike Gilbert wrote:	
> > On Sun, Jul 6, 2014 at 1:08 PM, Ivan Shapovalov <intelfx100 at gmail.com> wrote:
> > > On Sunday 06 July 2014 at 13:01:22, Leonid Isaev wrote:
> > >> Hi,
> > >>
> > >>       I have a read-only / filesystem and /etc/mtab points to
> > >> /proc/self/mounts as it should.
> > >>       So, in systemd-215 tmpfile.d fails to create a symbolic link /etc/mtab
> > >> because /usr/lib/tmpfiles.d/etc.conf contains is a line "L+ /etc/mtab - - - -
> > >> ../proc/self/mounts".
> > >>       Is this intentional? Besides failing on ro /, it is also confusing
> > >> because /etc/mtab can be supplied by a package (in archlinux, the 'filesystem'
> > >> package), so why tmpfiles instead of including this symlink with systemd?
> > >>       The same question applies to the entire etc.conf: why does tmpfiles
> > >> touch /etc at all, especially if /etc is already properly set up?
> > >>
> > >> Thanks,
> > >>
> > >
> > > L+ (as well as any other "+" directives) only force-overwrite files if this is
> > > needed, e. g. if a symlink points to the wrong desination.
> > >
> > 
> > Right.
> > 
> > I think the path matching is a little naive; Using a simple string
> > comparison, "/proc/self/mounts" != "../proc/self/mounts" even though
> > both paths refer to the same object.
> 
> No, they aren't referring to the same object. This makes a difference
> when you mount a "foreign" system image for maintainance.

Cool :(

So... the solution would be for distro packages to ship mtab as a symlink to
"../proc" instead of "/proc"?

Thanks,
-- 
Leonid Isaev
GPG fingerprints: DA92 034D B4A8 EC51 7EA6  20DF 9291 EE8A 043C B8C4
                  C0DF 20D0 C075 C3F1 E1BE  775A A7AE F6CB 164B 5A6D
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/systemd-devel/attachments/20140706/80a63e25/attachment-0001.sig>