From owner-freebsd-questions  Tue Sep 21 18:44:20 1999
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Date: Tue, 21 Sep 1999 19:00:35 -0700 (PDT)
From: Alfred Perlstein <bright@wintelcom.net>
To: Laurence Berland <stuyman@confusion.net>
Cc: Ben Smithurst <ben@scientia.demon.co.uk>,
	"Oleg V. Volkov" <rover@lglobus.ru>, freebsd-questions@FreeBSD.ORG
Subject: Re: How to find absolute name of running binary?
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On Tue, 21 Sep 1999, Laurence Berland wrote:

> So how do programs like gzip/gunzip do it?  Where running gunzip is the
> same as gzip -d?

because no one is going out of thier way to decieve the program of
the argv[0].  It wouldn't be standard practive to do so, but it can
be done:

#include <stdio.h>

int main (void) {
        char *spam[] = {
                "spam", NULL
        };
          
        execve("./t/tt", spam, NULL);

}

the program ./t/tt will see argv[0] as "spam" instead of "./t/tt"
most exec wrappers don't do this, so it would have to be intentional.

-Alfred

> 
> Ben Smithurst wrote:
> > 
> > Alfred Perlstein wrote:
> > 
> > > On Tue, 21 Sep 1999, Oleg V. Volkov wrote:
> > >
> > >> Well subject says it all. How could i find absolute name of my running
> > >> binary from inside it? References to man or C examples welcome.
> > >
> > > I think some permutation of getcwd(3) and argv[0] should help, perhaps
> > > with lstat (to check if you were run via a symlink)
> > 
> > That won't do much if people give the program crap in argv[0], e.g.
> > execlp("foo", "ha ha, fooled you!", "-x", "-y", "z", NULL), will
> > it? There's some about this in some FAQ somewhere (comp.unix.programmer
> > FAQ maybe, I'm not sure), and it basically boils down to "don't
> > do it". I'd like to know what Oleg is doing and why he needs this
> > information.
> > 
> > --
> > Ben Smithurst            | PGP: 0x99392F7D
> > ben@scientia.demon.co.uk |   key available from keyservers and
> >                          |   ben+pgp@scientia.demon.co.uk
> > 
> > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > with "unsubscribe freebsd-questions" in the body of the message
> 
> -- 
> Laurence Berland, Stuyvesant HS Debate
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
> Windows 98: n.
>         useless extension to a minor patch release for 
>         32-bit extensions and a graphical shell for a 
>         16-bit patch to an 8-bit operating system 
>         originally coded for a 4-bit microprocessor, 
>         written by a 2-bit company that can't stand for
>         1 bit of competition.
> http://stuy.debate.net
> icq #7434346                    aol imer E1101
> The above email Copyright (C) 1999 Laurence Berland
> All rights reserved
> 
> 
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