[Pm-utils] lockfile creation not really atomic in pm-utils

Till Maas opensource at till.name
Fri Jan 11 10:00:58 PST 2008

On Wed January 9 2008, Victor Lowther wrote:

> What happens when your device either does not have a hardware clock or
> the hardware clock has failed?  The more complicated the mechanism to
> detect and remove a stale lock directory, the more ways in which it
> can fail, and the more mysterious those failures will be.
> Unconditionally nuking the lock directory at boot time (or detecting
> the lock directory, annoying the user with some scary verbiage, and
> then unconditionally nuking the directory) is pretty much foolproof.

Hm, ok, I do not have any objections against the patch anymore. Only the need 
for cleaning up /.suspend manually in case of crashes / via an initscript 
should be documented in INSTALL imho.

> > > If there is a case in which suspend/resume fails, the system does not
> > > reboot (or hang and get rebooted), and the lock directory does not get
> > > removed, then that is a fault in the pm-utils scripting that needs
> > > fixed (imao).
> >
> > I agree here, but I do not know, whether this is currently the case or
> > not.
> Sounds like time for a code audit. I will look into it over the
> weekend and probably send a much larger patch. :)

I am not the author of pm-utils, so my knowledge of this does not mean much.

> Speaking of code audits, is there a reason that the scripts are bash
> specific in places?  I would think that strict POSIX sh compatibility
> would be the way to go for these scripts -- makes using them in
> embedded systems and the like easier.

Do you have a good resource on how to convert bash features into POSIX 
compatible commands? I guess bash is used, because it makes lot of stuff 
easier. :-)

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