libffi changes - help needed

[Steve McIntyre <steve@einval.com>]

Hi folks,

There's a problem with libffi that has been recently fixed - see

  http://lists.debian.org/debian-arm/2012/03/msg00108.html

for more information. So far, we only expect symptoms to show up on
armhf *but* it might be more widespread. Until recently, libffi didn't
support variadic functions properly. That's now been fixed in libffi,
but there's an extra API call necessary in places where variadics are
used.

In the scan of the archive I've just done, it seems that the vast
majority of the packages I can find that may be affected (i.e. callers
of "ffi_prep_cif" are implemented in Haskell. What I assume I'm seeing
here is simply a consequence of Haskell core code being embedded by
the compiler at compile time, so it should be possible to fix the
issue in one place and simply rebuild the affected packages.

So, I've looked at the ghc source code in an attempt to find/check/fix
this issue where possible. What I've found is that Haskell source
means *very* little to me (*grin*), so I'm here to ask for help from
some more knowledgeable people. Could one of you help with:

  * checking the code to see if variadics are passed/used
  * a patch to use ffi_prep_cif_var() where necessary

please?

Thanks!
-- 
Steve McIntyre, Cambridge, UK.                                steve@einval.com
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