From: Daniel Berger <djberg96@...>
Date: 2009-08-09T12:19:26+09:00
Subject: FFI, getutxent question

Hi

According to the man page, the prototypes for getutxent(), setutxent() 
and endutxent() are as follows:

void endutxent(void);
struct utmpx * getutxent(void);
void setutxent(void);

So, I declared them like so:

require 'ffi'

class Info
    extend FFI::Library

    attach_function :setutxent, [], :void
    attach_function :getutxent, [], :pointer
    attach_function :endutxent, [], :void

    def self.getstuff
       begin
          setutxent()
          p getutxent() # NULL Pointer ???
       ensure
          endutxent()
       end
    end
end

Info.getstuff # Null Pointer object

However, the call to getutxent() returns a NULL pointer. I'm guessing I 
have to tell it what kind of pointer to return, but I wasn't sure how to 
do that. How do I do that?

Regards,

Dan