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Re: File Locking

[ Please don't Cc: public replies to me. ]

Karl M. Hegbloom:
>  Ok.. Lars Wirzenius <liw@iki.fi> is the author and maintainer of
> publib.  Lars, are you reading us?

Sort of. I'll spend some more time on my Debian folder in a few
days' time, and will respond in full then.

However, I should point out at once that I don't know if my
lockfile.c will work properly in all situations. I've done the
best I can, based on manual pages, but I haven't been able to
test it over NFS when various errors happen. I'm not an expert
on this. I think I have some notes from Miquel somewhere,
and will try to find them. The problem is that one needs to
understand NFS and other failure modes to design the locking
code properly, and I don't understand NFS.

And it isn't enough to just create a lock file. If the creator
of the lock file crashes without removing the lock, everyone
still alive will starve. There should be a method for automatically
recovering from this, and that method must not rely on a daemon
purging lock files at suitable intervals. There's no good way
of doing this, as far as I can tell.

If and when procmail goes GPL, we should probably borrow the
locking code from there, and at least make our liblockfile be
based on that code.

> Lars Wirzenius?  What are your plans for publib?

To boldly code, where no luser has coded before.

(And yes, a shared library version is forthcoming, but I don't
know when. I've been meaning to look at GNU's libtool package
for a while now.)

Please read <http://www.iki.fi/liw/mail-to-lasu.html> before mailing me.
Please don't Cc: me when replying to my message on a mailing list.

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