/contrib/ntp/include/isc/magic.h

 1/*
 2 * Copyright (C) 1999-2001  Internet Software Consortium.
 3 *
 4 * Permission to use, copy, modify, and distribute this software for any
 5 * purpose with or without fee is hereby granted, provided that the above
 6 * copyright notice and this permission notice appear in all copies.
 7 *
 8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
 9 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
10 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
11 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
13 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
14 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
15 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/* $Id: magic.h,v 1.11 2001/01/09 21:57:10 bwelling Exp $ */
19
20#ifndef ISC_MAGIC_H
21#define ISC_MAGIC_H 1
22
23typedef struct {
24	unsigned int magic;
25} isc__magic_t;
26
27
28/*
29 * To use this macro the magic number MUST be the first thing in the
30 * structure, and MUST be of type "unsigned int".
31 *
32 * The intent of this is to allow magic numbers to be checked even though
33 * the object is otherwise opaque.
34 */
35#define ISC_MAGIC_VALID(a,b)	(((a) != NULL) && \
36				 (((const isc__magic_t *)(a))->magic == (b)))
37
38#define ISC_MAGIC(a, b, c, d)	((a) << 24 | (b) << 16 | (c) << 8 | (d))
39
40#endif /* ISC_MAGIC_H */