Re: [PATCH 05/22] lockfile: unlock file if lockfile permissions cannot be adjusted

> On Tue, Apr 01, 2014 at 05:58:13PM +0200, Michael Haggerty wrote:
> 
> > If the call to adjust_shared_perm() fails, lock_file returns -1, which
> > to the caller looks like any other failure to lock the file.  So in
> > this case, roll back the lockfile before returning so that the lock
> > file is deleted immediately and the lockfile object is left in a
> > predictable state that (namely, unlocked).  Previously, the lockfile
> > was retained until process cleanup in this situation.
> 
> Another nice find. I wondered if we could test this, but I think it
> would be hard to trigger. The obvious reason for adjust_shared_perm to
> fail is that you do not have permissions on the file, but by definition
> you just created it. So I doubt this ever comes up in practice short of
> weird races (somebody dropping the "x" bit from an intermediate
> directory between the open() and chmod() or something).