Ok, I tried out ffi-inliner to get the FD_SETSIZE macro, and that
seems to work, so I imagine the other shouldn't be too hard.

module Net
  module SNMP
    module Inline
      extend Inliner

      inline do |builder|
        builder.include "sys/select.h"
        builder.c %q{
          int fd_setsize() {
            return(FD_SETSIZE);
          }
        }
      end
    end
  end
end
fdset = FFI::MemoryPointer.new(:pointer,
Net::SNMP::Inline.fd_setsize / 8)


On Apr 29, 7:58 am, mixtli <ronmcclai...@gmail.com> wrote:

> Thank you.  That worked perfectly.
>
> Fortunately, I don't have to deal much with those macros because I'm
> using the net-snmp snmp_sess_select_info() function to prepare the
> descriptors.
> The only thing I have to do is allocate a pointer to an fd_set, which
> I've hardcoded as a FFI::MemoryPointer.new(:pointer, 128).  This works
> on my system,
> but I'm sure it's a bad idea.  I was considering using RubyInline to
> write simple wrappers around the macros.  I'll give that a shot
> tonight, unless you have a better suggestion.
>
> On Apr 29, 5:17 am, Aman Gupta <themastermi...@gmail.com> wrote:
>
>
>

> > You can use ffi_lib(FFI::CURRENT_PROCESS).

>

> > How are you emulating the FD_* macros via FFI?

>

> >   Aman

>

> > On Friday, April 29, 2011, mixtli <ronmcclai...@gmail.com> wrote:

> > > I wanted to call rb_thread_select to do some async polling, so I made
> > > a quick wrapper.  It actually works fine, but I have to specify the
> > > full path to my libruby.dylib in the call to ffi_lib.   If I just put
> > > "libruby", it segfaults.   Is there some standard mechanism for
> > > forcing ffi to use the libs from the rvm environment?   This is for a
> > > public gem (http://github.com/mixtli/net-snmp), so I'd like it to
> > > automagically work in the user's environment.

>

> > > Also, is there a standard set of wrappers for ruby internals similar
> > > to the set for libc (ffi-libc)?

>

> > > And finally, since I'm here..  Anyone else having problems requiring
> > > ffi-libc on snow leopard?  A bunch of the functions don't seem to be
> > > defined on my system (clearenv, stdin, etc).