1 /* $NetBSD: magic.h,v 1.3 2020/05/24 19:46:26 christos Exp $ */ 2 3 /* 4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC") 5 * 6 * This Source Code Form is subject to the terms of the Mozilla Public 7 * License, v. 2.0. If a copy of the MPL was not distributed with this 8 * file, You can obtain one at http://mozilla.org/MPL/2.0/. 9 * 10 * See the COPYRIGHT file distributed with this work for additional 11 * information regarding copyright ownership. 12 */ 13 14 #ifndef ISC_MAGIC_H 15 #define ISC_MAGIC_H 1 16 17 #include <isc/likely.h> 18 19 /*! \file isc/magic.h */ 20 21 typedef struct { 22 unsigned int magic; 23 } isc__magic_t; 24 25 /*% 26 * To use this macro the magic number MUST be the first thing in the 27 * structure, and MUST be of type "unsigned int". 28 * The intent of this is to allow magic numbers to be checked even though 29 * the object is otherwise opaque. 30 */ 31 #define ISC_MAGIC_VALID(a, b) \ 32 (ISC_LIKELY((a) != NULL) && \ 33 ISC_LIKELY(((const isc__magic_t *)(a))->magic == (b))) 34 35 #define ISC_MAGIC(a, b, c, d) ((a) << 24 | (b) << 16 | (c) << 8 | (d)) 36 37 #endif /* ISC_MAGIC_H */ 38