Re: fakeroot status

[Marcus Brinkmann]

On Tue, May 14, 2002 at 09:06:44PM -0400, Roland McGrath wrote:
> The file_exec call on the interpreter (sh) is where it goes from there.
> That in turn results in an ordinary exec_exec of the interpreter file.  
> If you're unclear on what happens after that, read exec.c:do_exec,
> S_exec_startup_get_info, and libc/hurd/hurdstartup.c.

Ah, the startup thing does it, I see now.
 
> > However, I verified that the /dev/fd/3 mechanism works in a non-fakeroot
> > environment.
> 
> Hmm.  Since it is getting the node to the underlying file in dtable[3],
> there shouldn't be any difference from fakeroot in how accessing /dev/fd/3
> works (unless the /dev/fd magic isn't working right).

Ha, that was way too easy with rpctrace.  It turns out that /dev/fd/3 is
looked up in the namespace of the fakeroot translator, which conveniently,
but in a fundamentally broken way looks up the node and does all the MAGIC
interpretation itself.

So, the client gets to see whatever is fd 3 in fakeroot, which is invalid in
this case.  The same should apply to all other magic retries.

The ultimate test was to set 3< /bin/bashbug in the fakeroot invocation, and
see!  All scripts that were broken before invoke bashbug from there on :)

Now, this starts to look as if using file_name_lookup_under was not the best
choice.  Can't we use dir_lookup directly?

Thanks,
Marcus

-- 
`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org
Marcus.Brinkmann@ruhr-uni-bochum.de
http://www.marcus-brinkmann.de