On Jan 12, 6:52 ¨Βν¬ Θεεσοβ Παςλ Όπθα®®®ΐηναιμ®γονΎ χςοτεΊ
> Hi,
>
> 2010/1/13 Daniel Berger <djber... / gmail.com>:
>
>
>
> > Hi,
>
> > I'm trying to wrap two function calls from kerberos, krb5_init_context
> > and krb5_free_context. Here are the prototypes for both:
>
> > krb5_init_context(krb5_context * context) => krb5_error_code
> > krb5_free_context(krb5_context context) => void
>
> > krb5_context is a struct, but unfortunately I don't know what its
> > members are.
>
> > From the docs:
>
> > The krb5_context structure is designed to hold all per thread
> > state. All
> > global variables that are context specific are stored in this
> > structure,
> > including default encryption types, credentials-cache (ticket
> > file), and
> > default realms.
>
> > The internals of the structure should never be accessed directly,
> > func-
> > tions exist for extracting information.
>
> > All I know is that it's 8 bytes in size.
>
> > I tried something like this, but it didn't work:
>
> > require 'ffi'
>
> > module Krb5
> >  ¨Βμασσ Γοξτεψ> >  ¨ΒψτεξΖΖΙΊΊΜιβςαςω
>
> >  ¨Βμασσ ΕςςοΣταξδαςδΕςςος» εξ>
> >  ¨Βζιίμιβ §λςⵧ
>
> >  ¨Βτταγθίζυξγτιοξ ΊλςβµίιξιτίγοξτεψτΫΊστςιξηέ¬ Ίυιξ> >  ¨Βτταγθίζυξγτιοξ ΊλςβµίζςεείγοξτεψτΫΊστςιξηέ¬ Ίφοι>
> >  ¨Βεζ ιξιτιαμιϊε
> >  ¨ΒγτΖΖΙΊΊΝενοςωΠοιξτες®ξεχ¨Ίποιξτες¬ Έ©
> >  ¨Βετ λςβµίιξιτίγοξτεψτ¨ΐγτψ>
> >  ¨Βςε> >  ¨Βαισε Εςςος¬ Άλςβµίιξιτίγοξτεψτ¨© ζαιμεδ> >  ¨Βξδ
>
> >  ¨ΒβμογλίηιφεξΏ
> >  ¨Βεηιξ
> >  ¨Βιεμδ σεμζ
> >  ¨Βξσυς> >  ¨Βςε> >  ¨Βξδ
> >  ¨Βξδ
> >  ¨Βξδ
>
> >  ¨Βεζ ζςεε
> >  ¨Βςβµίζςεείγοξτεψτ¨ΐγτψ©
> >  ¨Βξδ
> >  ¨Βξδ
> > end
>
> > k = Krb5::Context.new
> > k.free
>
> > I can use a plain string buffer, but then it segfaults on the 'free'
> > call.
>
> > Any suggestions?
>
> In my test platform, sizeof(krb5_context) is 4.
> Here is a working code:
>
> require 'ffi'
>
> module Krb5
>  ¨Βμασσ Γοξτεψ>  ¨ΒψτεξΖΖΙΊΊΜιβςαςω
>
>  ¨Βμασσ ΕςςοΣταξδαςδΕςςος» εξ>
>  ¨Βζιίμιβ §λςⵧ
>
>  ¨Βτταγθίζυξγτιοξ ΊλςβµίιξιτίγοξτεψτΫΊποιξτεςέΊυιξ>  ¨Βτταγθίζυξγτιοξ ΊλςβµίζςεείγοξτεψτΫΊυιξτέ¬ Ίφοι>
>  ¨Βεζ ιξιτιαμιϊε
>  ¨Βτς ΖΖΙΊΊΝενοςωΠοιξτες®ξεχ¨Ίγθας΄©
>  ¨Βετ λςβµίιξιτίγοξτεψτ¨πτς©
>  ¨Βςε>  ¨Βαισε Εςςος¬ Άλςβµίιξιτίγοξτεψτ¨© ζαιμεδ>  ¨Βξδ
>  ¨Βγτπτς®ςεαδίιξτ
>
>  ¨ΒβμογλίηιφεξΏ
>  ¨Βεηιξ
>  ¨Βιεμδ σεμζ
>  ¨Βξσυς>  ¨Βςε>  ¨Βξδ
>  ¨Βξδ
>  ¨Βξδ
>
>  ¨Βεζ ζςεε
>  ¨Βςβµίζςεείγοξτεψτ¨ΐγτψ©
>  ¨Βξδ
>  ¨Βξδ
> end
>
> k = Krb5::Context.new
> k.free

This almost got me there. I had to modify it somewhat to account for
the fact that I'm on Snow Leopard (x64), so I replaced :uint
with :long, 4 with 8 and ptr.read_int with ptr.read_long.

Now I need to figure out how to create an FFI::MemoryPointer without
necessarily knowing the size of the first argument.

Thanks for the help!

Regards,

Dan