Still no idea

gistfile1.txt

extern crate libc;

#[allow(non_camel_case_types)]
#[repr(C)]
type krb5_error_code = libc::c_int;

#[allow(non_camel_case_types)]
#[repr(C)]
struct krb5_context;

#[derive(Debug)]
struct Krb5Context {
    ctx: *mut krb5_context,
}

impl Krb5Context {
    fn new() -> Result<Krb5Context, krb5_error_code> {
        let rctx = unsafe {
            let mut kcontext: *mut krb5_context = std::ptr::null_mut();
            let err = krb5_init_context(&mut kcontext);
            if err == 0 {
                Ok(kcontext)
            } else {
                Err(err)
            }
        };
        match rctx {
            Ok(ctx) => Ok(Krb5Context{ctx: ctx}),
            Err(e) => Err(e),
        }
    }
}

impl Drop for Krb5Context {
    fn drop(&mut self) {
        println!("Freeing!");
        unsafe{
            krb5_free_context(self.ctx)
        }
    }
}

#[link(name = "krb5")]
extern "C" {
    fn krb5_init_context(context: *mut *mut krb5_context) -> krb5_error_code;
    fn krb5_free_context(context: *mut krb5_context);
}

fn main() {
    let kctx = Krb5Context::new();
    match kctx {
        Ok(ctx) => println!("{:?} YAY!", ctx),
        Err(e) => println!("{:?} OHNOES", e)
    }
}