Re: [ptxdist] system bash replacement

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Mon, Sep 11, 2017 at 10:59:09AM +0200, Erwin Rol wrote:
> On Mon, 2017-09-11 at 10:28 +0200, Michael Olbrich wrote:
> > On Sat, Sep 09, 2017 at 10:59:34AM +0200, Erwin Rol wrote:
> > > I have several (older) CentOS 6.X (and even 5.X :-/ ) systems that have
> > > bash 4.1.2 which is to old for newer ptxdist releases.
> > > 
> > > Ptxdist checks for several tools and places links in its $PTXDIR/bin/
> > > dir. Tools include cp, ls, awk, and bash. The ptxdist $PTXDIR/bin/ dir
> > > is placed in PATH so those links in $PTXDIR/bin/ are found first.
> > > 
> > > But! all ptxdist scripts have "#!/bin/bash" in them, so that bash link
> > > in $PTXDIR/bin/ is never used. 
> > > 
> > > I have some success by replacing "#!/bin/bash" with "#!/usr/bin/env
> > > bash" but before I go ahead with that I would like to hear if someone
> > > already tried that and failed (or succeeded).
> > > 
> > > BTW the same for the python link, scripts with #!/bin/python  will not
> > > use it. 
> > 
> > I've never tried this, but I had some ideas:
> > 
> > 1. We already set SHELL=$(PTXDIST_TOPDIR)/bin/bash in
> >    rules/other/Toplevel.make so that handles some of it.
> > 2. PTXdist itself is a problem. I had some ideas about re-executing ptxdist
> >    if the shell is different from $(PTXDIST_TOPDIR)/bin/bash.
> 
> I already have some "wrapper" around ptxdist so I have a bash there and
> that is first in the path so "#!/usr/bin/env bash" works for me. But
> that surely isn't a general solution for ptxdist.  

Yes that not so nice. That should be handled in ptxdist. We could add some
early check like this (untested):

if [ "$BASH_VERSION" != "$($(dirname $0)/bash -c 'echo $BASH_VERSION')" ]; then
	exec "$(dirname $0)/bash" "${0}" "${@}"
fi

Or something like that.

> BTW I found out the awk should be version checked, cause the CentOS 6
> awk silently fails, causing the dependencies to be not generated and so
> building just starts with some random package. 

A patch for configure.ac would be great :-)

> In the end things still didn't want to work right. So I ended up
> creating a chroot where I bind mount everything from the host under
> host_root. Than create a bin dir  and symlink everything from
> host_root/bin/. Than replace the bash link with the new bash (and the
> same with the awk). The other dirs like lib, etc, opt I just ln to the
> dir in host_root. After that I can chroot in it and everything looks
> like my host but with a new shell and awk. Also had to get a new host
> GCC (4.4.8 is to old for the toolchain building). But in the end I was
> able to build the lastest ptxdist toolchain on Centos 6 without changing
> the host OS. 
> 
> It is like a mini "container", if I would selectively setup usr/lib/ and
> usr/include it could also be used to prevent pulling in host stuff. 

So what else fails? Is it within ptxdist or while building packages?

Regards,
Michael


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