Fiddle::Handle#sym_defined?

static VALUE
rb_fiddle_handle_sym_defined(VALUE self, VALUE sym)
{
    struct dl_handle *fiddle_handle;
    fiddle_void_func func;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    if( ! fiddle_handle->open ){
        rb_raise(rb_eFiddleDLError, "closed handle");
    }

    func = fiddle_handle_find_func(fiddle_handle->ptr, sym);

    if( func ) {
        return PTR2NUM(func);
    }
    else {
        return Qnil;
    }
}