Function get_attr_byname 

pub unsafe extern "C" fn get_attr_byname(
    context: *mut c_context,
    value: *const value,
    state: *mut EvalState,
    name: *const c_char,
) -> *mut value

@brief Get an attr by name @ingroup value_extract

Call nix_value_decref() when you’re done with the pointer @param[out] context Optional, stores error information @param[in] value Nix value to inspect @param[in] state nix evaluator state @param[in] name attribute name @return value, NULL in case of errors