From: Rob Landley <rob@landley.net>
To: Denis Vlasenko <vda.linux@googlemail.com>
Subject: Re: Feature request: exec self for NOMMU.
Date: Wed, 27 Dec 2006 16:03:38 -0500
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Cc: ray-gmail@madrabbit.org, linux-kernel@vger.kernel.org,
       "David McCullough" <david_mccullough@au.securecomputing.com>
References: <200612261823.07927.rob@landley.net> <2c0942db0612262113v5b504aecmdd922193415b60de@mail.gmail.com> <200612271935.07835.vda.linux@googlemail.com>
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On Wednesday 27 December 2006 1:35 pm, Denis Vlasenko wrote:
> This solves chroot problem. How to find path-to-yourself reliably
> (for one, without using /proc/self/exe) is not obvious to me.

Been there, done that.  Both my toybox and Firmware Linux projects do this.  
In FWL it's line 115 of this file:
http://landley.net/hg/firmware?f=937346748ff4;file=sources/toys/gcc-uClibc.c

It's essentially the logic of the command line "which" utility applied to 
argv[0].  If argv[0] has a relative or absolute path, then it's vs cwd (this 
has to happen when you first run the program, before you cd).  If argv[0] has 
no path then look at $PATH.

Rob
-- 
"Perfection is reached, not when there is no longer anything to add, but
when there is no longer anything to take away." - Antoine de Saint-Exupery
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