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From: dprrhb@inetg1.ARCO.COM (Reginald H. Beardsley)
Newsgroups: comp.os.minix
Subject: Re: source for open(2)
Message-ID: <1991May8.192535.12247@Arco.COM>
Date: 8 May 91 19:25:35 GMT
References: <53017@nigel.ee.udel.edu>
Sender: dprrhb@inetg1 (Reginald H. Beardsley)
Organization: ARCO Oil & Gas Company
Lines: 37

Thanks for the responses.  I find I was not clear about what I'm up to.

My concern is not with a specific executable with hard paths, but rather 
the more general problem of testing software on a production machine where
it is necessary to have two copies of the same code which the user is able
then to select his choice at run time.  This is SOP in large shops running VMS
or MVS.  If people wrote their code for the Unix environment using 
environment variables to set paths, this wouldn't be such a problem.
Unfortunately, too many people have emulated the sins of the Unix source
code.(cf. the articles on BSD-386 by Jolitz in Dr. Dobb's).

Unix was designed as a research tool, not as a production OS.  It meets its
design goals extremely well.  The rapid pace of hardware development has
led to our using Unix for many things for which it was not designed.

Because I have the source for Minix and a cheap machine to run it on I can experiment with possible fixes for some of these.  They won't let me take over the Cray to test a recompiled kernel with Reg's patches.  Since I don't want to have to support the OS all by myself, I wouldn't patch it even if they were to let me.

The traditional Unix solution of symbolic links is unsatisfactory for two reasons.  First, it requires write access someplace the user should not have it. Second, it is global and effects all users of the system, thus failing 
my requirement to run both test and production code on the same system at the 
same time.

Andy may have written Minix for the purpose of teaching operating systems 
design and implementation, but I'm sure I'm not the only one who finds it 
very useful for many other things.  I'm still spending most of my time 
patching code and learning about the OS, but I'm also outlining some serious 
work which will use Minix as the test bed. 

PS:  There are some potentially serious security implications for the 
basic idea of revectoring hard paths through a table.  What about a user
substituting his own version of /etc/passwd?

-- 
Reginald H. Beardsley       
ARCO Information Services
Plano, TX 75075           
Phone: (214)-754-6785
Internet: dprrhb@arco.com