From: Guillaume Marcais <guslist@...>
Date: 2004-12-09T00:13:18+09:00
Subject: Pointer of pointer with Ruby/DL

I have the following C prototype:

int auth(char *user, char *passwd, char **msgp);

I pass user and passwd, and I get in response 0 or 1 for success or
failure and a message in *msgp.

How can i call this function from Ruby using Ruby/DL? So far I did the
following:

<code>
module Auth
  extend DL::Importable
  dlload "./auth.so"
  extern "int auth(char *, char *, char **)"
end

msgp = [0].pack('L').to_ptr
r = Tenant2Auth.public_tenant2_auth_pap_auth("coucou", "titi", msgp)
</code>

I get the correct result in 'r'. But how do I get access to the string
in *msgp?

I guess I don't yet have a good grasp on pointer dereferencing with
Ruby/DL.

Anyone?

Guillaume.