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Date:      Sun, 24 Jun 2001 09:54:03 -0700
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        <des@ofug.org>
Cc:        <js43064n@pace.edu>, <freebsd-questions@FreeBSD.ORG>, <freebsd-stable@FreeBSD.ORG>, <freebsd-security@FreeBSD.ORG>
Subject:   RE: Kernel Panic
Message-ID:  <006501c0fcce$45fc5080$1401a8c0@tedm.placo.com>
In-Reply-To: <xzp8zih7sm6.fsf@flood.ping.uio.no>

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>-----Original Message-----
>From: des@ofug.org [mailto:des@ofug.org]
>Sent: Sunday, June 24, 2001 9:25 AM
>To: Ted Mittelstaedt
>Cc: js43064n@pace.edu; freebsd-questions@FreeBSD.ORG;
>freebsd-stable@FreeBSD.ORG; freebsd-security@FreeBSD.ORG
>Subject: Re: Kernel Panic
>
>
>"Ted Mittelstaedt" <tedm@toybox.placo.com> writes:
>> That's a case I hadn't thought of - however, "local" search paths should
>> generally be at the END of the user's path, not the beginning,
>in which case
>> the system binary gets called first.
>
>No!  Local paths should be at the beginning, so local binaries
>(wrappers etc.) can ovverride system binaries.
>

I was half-expecting you to say something like that.

In response:  NO, local wrappers should NEVER be named the same as system
binaries because the user then gets used to assuming that the wrapper is
in place for all systems

Imagine a local wrapper named "rm" that instead of deleting the file
puts it in a "garbage pail".  You get used to the garbage pail and get
sloppy in what you remove - then one day your on another system and do an
"rm" without thinking, then realize a mistake, go to the "garbage pail" and
find that it doesen't exist.  Wahhh!!!!

Now, if you are the administrator and you want to wrap a system binary then
you do it by renaming the system binary something else, and putting the
wrapper in the place the system binary is.  But that's not a case of a local
binary.

>> Both cases are bad practice, and shouldn't be present on a normal system.
>
>Bollocks.
>

Bollocks back.  If you name your local wrappers your own names then the
wrapper works fine if the local path is at the end of the search path.

I can see putting the local path at the front for TEMPORARY use - like if
you
were developing a system binary you wanted to repeatedly test - but you
go on a big limb by making a bunch of custom wrappers that duplicate
the system binary names.

>> I think in that situation you would have to have a swap partition that's
>> smaller than the maximum amount of ram that a normal user is permitted to
>> allocate - in that case the limits are set too high.
>
>That, or the limits simply don't account for all the resources a user
>can consume, as is the case with mmap().
>

OK - but then this is a case where the limiting device is broken.  Maybe
that should be worked on as well as the swap problem too, no?


Ted Mittelstaedt                      tedm@toybox.placo.com
Author of:          The FreeBSD Corporate Networker's Guide
Book website:         http://www.freebsd-corp-net-guide.com



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