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Date:      Sat, 10 Jan 1998 20:07:39 -0800 (PST)
From:      Simon Shapiro <shimon@simon-shapiro.org>
To:        Alex Nash <nash@mcs.net>
Cc:        current@freebsd.org
Subject:   Re: Firewall in kernel? - Found it!
Message-ID:  <XFMail.980110200739.shimon@simon-shapiro.org>
In-Reply-To: <199801110341.VAA11086@nash.pr.mcs.net>

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On 11-Jan-98 Alex Nash wrote:

...

>> In this model, the first to grab a ``lock'' on IP firewalls, will
becone
>> the
>> focal point (the ``submitter'') for all code relating to IP firewalls.
> 
> How do you define who all the afflicted parties are?  Locking
> /etc/rc.conf seems an extreme price to pay for working on the firewall
> code.  And what about libalias?  Until two days ago there were no ties
> between it and ipfw, so again the problem would have gone unchecked. 
> Now you could say that the committer of the libalias code has to lock
> ipfw beforehand, but locking a subsystem because you plan to use its
> interface seems extreme.

You assume the existing data model for a source tree.  This model is
file-centric and assumes mutex locks only.

My model is fragment-centric and dependencies are computed dynamically and
automatically.  In addition, locks are multi level, so that if you chage a
header file, you force refresh (not lock-out) on .c files, etc.
Also, note that the first authoritative lock on firewall code will force
all other checkouts to checkin via the authoritative lock.
That /etc/rc is now dependant on some .c file can either be deduced from
source relations, or...  has to be entered manually.

Consider:

foo >& /dev/null
if [${?} != 0]
...

as a dependancy.  Now can we reliably abstract it mechanically?
Probably.  Do I (Simon) kow how to do it?  Maybe.  Is there a FreeBSD
hacker around who know better and has time to write such a tool?  I am sure
the answer is yes.

----------


Sincerely Yours, 

Simon Shapiro
Shimon@Simon-Shapiro.ORG                      Voice:   503.799.2313



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