linux-kernel - Re: Feature request: exec self for NOMMU.

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Message-Id: <200612271603.39454.rob@landley.net>
Date:	Wed, 27 Dec 2006 16:03:38 -0500
From:	Rob Landley <rob@...dley.net>
To:	Denis Vlasenko <vda.linux@...glemail.com>
Cc:	ray-gmail@...rabbit.org, linux-kernel@...r.kernel.org,
	"David McCullough" <david_mccullough@...securecomputing.com>
Subject: Re: Feature request: exec self for NOMMU.

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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