usr.sbin/rdate/ntpleaps.h

   1 /*      $OpenBSD: src/usr.sbin/rdate/ntpleaps.h,v 1.3 2004/05/05 20:29:54 jakob Exp $   */
   2 /*      $DragonFly: src/usr.sbin/rdate/ntpleaps.h,v 1.1 2004/12/01 15:04:43 joerg Exp $ */
   3
   4 /*
   5  * Copyright (c) 2002 Thorsten Glaser. All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  *    - Redistributions of source code must retain the above copyright
  12  *      notice, this list of conditions and the following disclaimer.
  13  *    - Redistributions in binary form must reproduce the above
  14  *      copyright notice, this list of conditions and the following
  15  *      disclaimer in the documentation and/or other materials provided
  16  *      with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  22  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  26  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  28  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  *
  31  */
  32
  33 /* Leap second support for SNTP clients
  34  * This header file and its corresponding C file provide generic
  35  * ability for NTP or SNTP clients to correctly handle leap seconds
  36  * by reading them from an always existing file and subtracting the
  37  * leap seconds from the NTP return value before setting the posix
  38  * clock. This is fairly portable between operating systems and may
  39  * be used for patching other ntp clients, too. The tzfile used is:
  40  * /usr/share/zoneinfo/right/UTC which is available on any unix-like
  41  * platform with the Olson tz library, which is necessary to get real
  42  * leap second zoneinfo files and userland support anyways.
  43  */
  44
  45 #ifndef _NTPLEAPS_H
  46 #define _NTPLEAPS_H
  47
  48 /* Offset between struct timeval.tv_sec and a tai64_t */
  49 #define NTPLEAPS_OFFSET (4611686018427387914ULL)
  50
  51 /* Hide this ugly value from programmes */
  52 #define SEC_TO_TAI64(s) (NTPLEAPS_OFFSET + (u_int64_t)(s))
  53 #define TAI64_TO_SEC(t) ((t) - NTPLEAPS_OFFSET)
  54
  55 /* Initializes the leap second table. Does not need to be called
  56  * before usage of the subtract funtion, but calls ntpleaps_read.
  57  * returns 0 on success, -1 on error (displays a warning on stderr)
  58  */
  59 int ntpleaps_init(void);
  60
  61 /* Re-reads the leap second table, thus consuming quite much time.
  62  * Ought to be called from within daemons at least once a month to
  63  * ensure the in-memory table is always up-to-date.
  64  * returns 0 on success, -1 on error (leap seconds will not be available)
  65  */
  66 int ntpleaps_read(void);
  67
  68 /* Subtracts leap seconds from the given value (converts NTP time
  69  * to posix clock tick time.
  70  * returns 0 on success, -1 on error (time is unchanged), 1 on leap second
  71  */
  72 int ntpleaps_sub(u_int64_t *);
  73
  74 #endif