Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mojsys!joevl
From: joevl@mojsys.com (Joe Vlietstra)
Newsgroups: comp.sys.hp
Subject: Re: Mediainit "not owner" error
Summary: Use setuid shell script
Message-ID: <1991Feb15.221447.600@mojsys.com>
Date: 15 Feb 91 22:14:47 GMT
References: <11950@pt.cs.cmu.edu>
Reply-To: joevl@mojsys.UUCP (Joe Vlietstra)
Organization: Mojave Systems Corporation, Claremont, CA
Lines: 34

In article <11950@pt.cs.cmu.edu> tgl@g.gp.cs.cmu.edu (Tom Lane) writes:
>When I try to use mediainit(1) on a floppy disk, it says
>	mediainit: can't lock volume - Not owner
>unless I am root.
>I tried changing the ownership of the device file to be myself,
>and it still wouldn't work.
>
>What's the problem?  Can I fix things so that unprivileged users
>can init a floppy?  Where in the manual is this discussed??

mediainit is described in "System Administration Tasks",
page 6-14.  The first step in the procedure is:
	1. Log in as the root user.
This is the only place in the documentation where it is
mentioned that only root may use mediainit.

mediainit doesn't distinguish between hard disks and floppy
disks -- it only ensures that the disk is not a mounted volume.
Requiring root to execute mediainit is a safety "feature."

Our work-around is a small shell script in /usr/local/bin:
	#!/bin/sh
	# Initialize a floppy disk
	/usr/bin/mediainit	/dev/rfloppy
This script is owned by root and has setuid.  This works for us
since we're a small company.  A larger organization may want to
use a lock file and other safety enhancements.

				Joe Vlietstra
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