From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gustavo Zacarias <gustavo@zacarias.com.ar>
Date: Wed, 9 Mar 2016 11:40:22 -0300
Subject: [Buildroot] [PATCH] pkgconf: make wrapper relocatable
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On 09/03/16 11:37, Arnout Vandecappelle wrote:

>> Yes, that's basically what I'm saying +/- the question if you want to
>> rely on $0 containing the full path to the wrapper or if you use
>> /proc/self/exe instead.
>
>   $0 will always contain the full relative path to the wrapper, no? Even
> if it was found through PATH, the PATH search is done by libc so the
> shell will be invoked with the full (absolute or relative) path to the
> wrapper and use that as $0. Or am I missing something?
>
>   I think the /proc/self/exe thing was something to deal with symlinks,
> which isn't the issue here.

Indeed, take the following example:

---
#!/bin/sh

TUPLE=powerpc-buildroot-linux-uclibcspe
WRAPPER_DIR=$(dirname $0)
STAGING_DIR=$(readlink -f ${WRAPPER_DIR}/../${TUPLE}/sysroot)

echo Invocation: $0
echo Wrapper dir: $WRAPPER_DIR
echo Staging dir: $STAGING_DIR
---

Run full pathspec /home/gustavoz/b/router03/output/host/usr/bin/ja:

Invocation: /home/gustavoz/b/router03/output/host/usr/bin/ja
Wrapper dir: /home/gustavoz/b/router03/output/host/usr/bin
Staging dir: 
/home/gustavoz/b/router03/output/host/usr/powerpc-buildroot-linux-uclibcspe/sysroot

Run in-place ./ja:

Invocation: ./ja
Wrapper dir: .
Staging dir: 
/home/gustavoz/b/router03/output/host/usr/powerpc-buildroot-linux-uclibcspe/sysroot

We can add a check to see if ${STAGING_DIR} is defined on and avoid 
(re)setting it when it is.

if [ -z ${STAGING_DIR} ]; then magic; fi

Regards.