magic.h revision 290001 
1/*
2 * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2001  Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/* $Id: magic.h,v 1.18 2007/06/19 23:47:18 tbox Exp $ */
19
20#ifndef ISC_MAGIC_H
21#define ISC_MAGIC_H 1
22
23/*! \file isc/magic.h */
24
25typedef struct {
26	unsigned int magic;
27} isc__magic_t;
28
29
30/*%
31 * To use this macro the magic number MUST be the first thing in the
32 * structure, and MUST be of type "unsigned int".
33 * The intent of this is to allow magic numbers to be checked even though
34 * the object is otherwise opaque.
35 */
36#define ISC_MAGIC_VALID(a,b)	(((a) != NULL) && \
37				 (((const isc__magic_t *)(a))->magic == (b)))
38
39#define ISC_MAGIC(a, b, c, d)	((a) << 24 | (b) << 16 | (c) << 8 | (d))
40
41#endif /* ISC_MAGIC_H */
42