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From: Denis Vlasenko <vda.linux@googlemail.com>
To: Rob Landley <rob@landley.net>
Subject: Re: Feature request: exec self for NOMMU.
Date: Thu, 28 Dec 2006 03:48:16 +0100
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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> <200612271935.07835.vda.linux@googlemail.com> <200612271603.39454.rob@landley.net>
In-Reply-To: <200612271603.39454.rob@landley.net>
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On Wednesday 27 December 2006 22:03, Rob Landley wrote:
> 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.

Yes Rob, I know it can be done like this. But we don't want this.
In the tar example, we want :

'Run my own binary again, with parameters: "zcat" "a.tar.gz",
even if there is no [/usr][/local]/bin/zcat -> busybox link anywhere'

We do not want to _search for_ zcat. We want to reexec our own binary.
--
vda
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