Path: utzoo!attcan!uunet!jarthur!usc!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!uflorida!haven!uvaarpa!mmdf
From: tytso@athena.mit.edu (Theodore Ts'o)
Newsgroups: comp.lang.perl
Subject: Subtle effects of DOSUID
Message-ID: <1990Mar21.235646.22870@uvaarpa.Virginia.EDU>
Date: 21 Mar 90 23:56:46 GMT
Sender: mmdf@uvaarpa.Virginia.EDU (Uvaarpa Mail System)
Reply-To: tytso@athena.mit.edu
Organization: The Internet
Lines: 26

Because of our setup of where perl is located (which I, unfortunately,
have no control over), I need to start perl scripts as follows:

#!/afs/athena.mit.edu/contrib/watchmaker/@sys/perl

Of course, this doesn't work, because of the kernel limit of 32
characters for the interpreter name.  So, my standard way of starting
perl scripts is as follows (yes, I know, what a hack):

#!/bin/sh
eval "exec /afs/athena.mit.edu/contrib/watchmaker/@sys/perl -S $0 $*"
    if $running_under_some_shell;

Which worked fine, until I tried compiling perl with DOSUID.
Apparently, one of the checks enabled by DOSUID (which it does even
though the script is not setuid) is to see if the interpreter
specified in the #! line is perl --- and if it isn't, to exec the named
interpreter and feed the script to it.  Of course, this causes a loop
and perl never gets a chance to execute my script.

My question is:  why is it doing the check even though the script is not
setuid?
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Theodore Ts'o				bloom-beacon!mit-athena!tytso
3 Ames St., Cambridge, MA 02139		tytso@athena.mit.edu
   Everybody's playing the game, but nobody's rules are the same!