dist/ntp/include/isc/magic.h

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 1999-2001  Internet Software Consortium.
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
  11  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  12  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  13  * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  15  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  16  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  17  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 /* Id: magic.h,v 1.11 2001/01/09 21:57:10 bwelling Exp */
  21
  22 #ifndef ISC_MAGIC_H
  23 #define ISC_MAGIC_H 1
  24
  25 typedef 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  *
  34  * The intent of this is to allow magic numbers to be checked even though
  35  * the object is otherwise opaque.
  36  */
  37 #define ISC_MAGIC_VALID(a,b)    (((a) != NULL) && \
  38                                  (((const isc__magic_t *)(a))->magic == (b)))
  39
  40 #define ISC_MAGIC(a, b, c, d)   ((a) << 24 | (b) << 16 | (c) << 8 | (d))
  41
  42 #endif /* ISC_MAGIC_H */