contrib/bind-9.2.4rc7/lib/isc/include/isc/magic.h

   1 /*
   2  * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and 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 1.11.2.1 2004/03/09 06:11:58 marka Exp $ */
  19
  20 #ifndef ISC_MAGIC_H
  21 #define ISC_MAGIC_H 1
  22
  23 typedef 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 */