Jim Henderson wrote:
> You'd have to configure things pretty weird to get part of the relevant 
> filesystems mounted in a way that was inconsistent with the requirements 

Sure.  However, you're looking at it from the narrow context of one 
particular program under Linux.  Being able to deal with such problems 
in a generic way is a benefit.

>>>> B) find that it's open by someone else as a shared text segment,
>>> I don't believe that would matter,
>> You're mistaken.
> 
> Well, it's something I've never run into, and I've only been running 
> Linux for about 12 years...

http://www.derkeiler.com/Mailing-Lists/FreeBSD-Security/2002-07/10992.html

It's not really common, unless you're trying to update executables while 
they're running. It's not hard to make it happen. We've been over that 
here, a few weeks ago.

> Well, the installer does just that - it unlinks and creates new files, 
> near as I can tell.  

Most likely. Probably because (d'oh) you can't write to a file that's 
being executed, yes? ;-)

>>>> C) run out of disk space,
>>> That would create other problems as well
>> Yes? So?  We know it's bad and you should avoid it, yes.
> 
> My point is that you would notice this probably before running out of 
> disk space.

Unless the update is what runs you out of space, or (just maybe) there's 
more than one person using the computer, like? Or some background job 
that's maybe doing something like receiving email?

>> And if the package manager updates the database *before* it updates the
>> files, you might never know it.
> 
> If you never know it, though, then things are working as expected

And if "as expected" means "still has the security holes in it that the 
update was supposed to patch", then yes, that's as expected. Not what 
you want, but as expected. :-)


But yes, if you're only talking about package management per se (which 
is indeed where we started) then there are obviously solutions in place. 
It's just a shame they didn't generalize it so you can make it work for 
other people too, or over the network, or in spite of failures, etc.

-- 
Darren New / San Diego, CA, USA (PST)

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