[OpenAFS] unpagsh fails with recent glibc

[Dr A V Le Blanc]

I asked about the failure of 'unpagsh' under kernels 2.6.x, and
Jeffrey Hutzelman replied:

On Tue, Mar 08, 2005 at 11:01:35AM -0500, Jeffrey Hutzelman wrote:
> That's not surprising.  unpagsh is not my code, but I did take a quick look 
> at it when you posted your first message.  It works by overflowing the 
> fixed-size group list maintained by the kernel with "real" groups, leaving 
> no room for the groups added by AFS to represent the PAG.  In Linux 2.6, 
> the list of groups associated with a process is not a fixed-size array; it 
> is dynamic, and our setgroups wrapper always grows the list to make room 
> for the PAG groups.  So you can't get rid of them by overflowing the array.
> 
> Making this work would require a change to the OpenAFS kernel code.

Isn't there a way -- not necessarily specifically using OpenAFS kernel
features -- to get rid of a group without doing something dodgy?
One can assume, for my purposes, that one is root and so on.
As far as I can see, there are standard ways only to add a group
to a process, not to get rid of it.  It would be adequate if one could
create a new process with the AFS groups left out...  I don't see how
to do such a thing using existing library functions.

     -- Owen
     LeBlanc@mcc.ac.uk