Date: Tue, 24 Aug 1999 19:13:36 +0930 From: Greg Lehey <grog@lemis.com> To: Ville-Pertti Keinonen <will@iki.fi> Cc: John-Mark Gurney <gurney_j@resnet.uoregon.edu>, hackers@freebsd.org Subject: Re: Mandatory locking? Message-ID: <19990824191335.O83273@freebie.lemis.com> In-Reply-To: <86pv0djz6o.fsf@not.demophon.com>; from Ville-Pertti Keinonen on Tue, Aug 24, 1999 at 12:38:38PM %2B0300 References: <19990823223645.A14001@netmonger.net> <19990824021431.55023@hydrogen.fircrest.net> <86pv0djz6o.fsf@not.demophon.com>
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On Tuesday, 24 August 1999 at 12:38:38 +0300, Ville-Pertti Keinonen wrote:
>
> gurney_j@efn.org (John-Mark Gurney) writes:
>
>> Ville-Pertti Keinonen scribbled this message on Aug 24:
>
>>> cat writes part of oldmail to /var/mail/grog
>>> sendmail locks /var/mail/grog
>>> (cat may try to write more to /var/mail/grog but blocks)
>>> sendmail delivers new mail
>>> sendmail unlocks /var/mail/grog
>>> cat writes the rest of oldmail to /var/mail/grog
>>>
>>> You'll still probably end up with a broken mailbox.
>>
>> what you do is this:
>> lockf -k $mailfile cat ${mailtmp} >> $mailfile
>
> Which doesn't support Greg's arguments for mandatory locking, as
> you're now doing locking in both programs.
Well, it doesn't support the last argument I made, which was
untenable. It doesn't affect most of the others. And we're some
distance from the dreaded deadlocks.
Greg
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