309 lines
8.3 KiB
C
309 lines
8.3 KiB
C
/* $NetBSD: mktime.c,v 1.3 2003/12/04 16:23:37 drochner Exp $ */
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/*
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* Copyright (c) 1987, 1989 Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Arthur David Olson of the National Cancer Institute.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE. */
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/*static char *sccsid = "from: @(#)ctime.c 5.26 (Berkeley) 2/23/91";*/
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/*static char *rcsid = "mktime.c,v 1.1.1.3 1998/11/15 19:23:34 kardel RELEASE_19990228_A";*/
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/*
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* This implementation of mktime is lifted straight from the NetBSD (BSD 4.4)
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* version. I modified it slightly to divorce it from the internals of the
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* ctime library. Thus this version can't use details of the internal
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* timezone state file to figure out strange unnormalized struct tm values,
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* as might result from someone doing date math on the tm struct then passing
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* it to mktime.
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*
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* It just does as well as it can at normalizing the tm input, then does a
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* binary search of the time space using the system's localtime() function.
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*
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* The original binary search was defective in that it didn't consider the
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* setting of tm_isdst when comparing tm values, causing the search to be
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* flubbed for times near the dst/standard time changeover. The original
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* code seems to make up for this by grubbing through the timezone info
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* whenever the binary search barfed. Since I don't have that luxury in
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* portable code, I have to take care of tm_isdst in the comparison routine.
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* This requires knowing how many minutes offset dst is from standard time.
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*
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* So, if you live somewhere in the world where dst is not 60 minutes offset,
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* and your vendor doesn't supply mktime(), you'll have to edit this variable
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* by hand. Sorry about that.
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*/
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#include "ntp_machine.h"
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#if !HAVE_MKTIME || !HAVE_TIMEGM
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#ifndef DSTMINUTES
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#define DSTMINUTES 60
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#endif
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#define FALSE 0
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#define TRUE 1
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/* some constants from tzfile.h */
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#define SECSPERMIN 60
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#define MINSPERHOUR 60
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#define HOURSPERDAY 24
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#define DAYSPERWEEK 7
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#define DAYSPERNYEAR 365
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#define DAYSPERLYEAR 366
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#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
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#define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY)
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#define MONSPERYEAR 12
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#define TM_YEAR_BASE 1900
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#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
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extern time_t time P((time_t *));
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static int mon_lengths[2][MONSPERYEAR] = {
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{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
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{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
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};
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static int year_lengths[2] = {
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DAYSPERNYEAR, DAYSPERLYEAR
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};
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/*
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** Adapted from code provided by Robert Elz, who writes:
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** The "best" way to do mktime I think is based on an idea of Bob
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** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now).
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** It does a binary search of the time_t space. Since time_t's are
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** just 32 bits, its a max of 32 iterations (even at 64 bits it
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** would still be very reasonable).
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*/
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#ifndef WRONG
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#define WRONG (-1)
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#endif /* !defined WRONG */
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static void
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normalize(
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int * tensptr,
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int * unitsptr,
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int base
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)
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{
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if (*unitsptr >= base) {
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*tensptr += *unitsptr / base;
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*unitsptr %= base;
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} else if (*unitsptr < 0) {
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--*tensptr;
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*unitsptr += base;
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if (*unitsptr < 0) {
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*tensptr -= 1 + (-*unitsptr) / base;
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*unitsptr = base - (-*unitsptr) % base;
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}
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}
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}
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static struct tm *
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mkdst(
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struct tm * tmp
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)
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{
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/* jds */
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static struct tm tmbuf;
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tmbuf = *tmp;
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tmbuf.tm_isdst = 1;
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tmbuf.tm_min += DSTMINUTES;
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normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR);
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return &tmbuf;
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}
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static int
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tmcomp(
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register struct tm * atmp,
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register struct tm * btmp
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)
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{
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register int result;
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/* compare down to the same day */
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if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
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(result = (atmp->tm_mon - btmp->tm_mon)) == 0)
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result = (atmp->tm_mday - btmp->tm_mday);
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if(result != 0)
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return result;
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/* get rid of one-sided dst bias */
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if(atmp->tm_isdst == 1 && !btmp->tm_isdst)
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btmp = mkdst(btmp);
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else if(btmp->tm_isdst == 1 && !atmp->tm_isdst)
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atmp = mkdst(atmp);
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/* compare the rest of the way */
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if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
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(result = (atmp->tm_min - btmp->tm_min)) == 0)
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result = atmp->tm_sec - btmp->tm_sec;
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return result;
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}
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static time_t
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time2(
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struct tm * tmp,
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int * okayp,
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int usezn
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)
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{
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register int dir;
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register int bits;
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register int i;
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register int saved_seconds;
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time_t t;
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struct tm yourtm, mytm;
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*okayp = FALSE;
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yourtm = *tmp;
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if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
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normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
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normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
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normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
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normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
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while (yourtm.tm_mday <= 0) {
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--yourtm.tm_year;
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yourtm.tm_mday +=
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year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
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}
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for ( ; ; ) {
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i = mon_lengths[isleap(yourtm.tm_year +
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TM_YEAR_BASE)][yourtm.tm_mon];
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if (yourtm.tm_mday <= i)
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break;
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yourtm.tm_mday -= i;
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if (++yourtm.tm_mon >= MONSPERYEAR) {
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yourtm.tm_mon = 0;
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++yourtm.tm_year;
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}
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}
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saved_seconds = yourtm.tm_sec;
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yourtm.tm_sec = 0;
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/*
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** Calculate the number of magnitude bits in a time_t
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** (this works regardless of whether time_t is
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** signed or unsigned, though lint complains if unsigned).
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*/
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for (bits = 0, t = 1; t > 0; ++bits, t <<= 1)
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;
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/*
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** If time_t is signed, then 0 is the median value,
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** if time_t is unsigned, then 1 << bits is median.
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*/
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t = (t < 0) ? 0 : ((time_t) 1 << bits);
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for ( ; ; ) {
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if (usezn)
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mytm = *localtime(&t);
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else
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mytm = *gmtime(&t);
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dir = tmcomp(&mytm, &yourtm);
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if (dir != 0) {
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if (bits-- < 0)
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return WRONG;
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if (bits < 0)
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--t;
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else if (dir > 0)
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t -= (time_t) 1 << bits;
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else t += (time_t) 1 << bits;
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continue;
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}
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if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
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break;
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return WRONG;
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}
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t += saved_seconds;
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if (usezn)
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*tmp = *localtime(&t);
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else
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*tmp = *gmtime(&t);
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*okayp = TRUE;
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return t;
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}
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#else
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int mktime_bs;
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#endif /* !HAVE_MKTIME || !HAVE_TIMEGM */
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#if !HAVE_MKTIME
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static time_t
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time1(
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struct tm * tmp
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)
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{
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register time_t t;
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int okay;
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if (tmp->tm_isdst > 1)
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tmp->tm_isdst = 1;
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t = time2(tmp, &okay, 1);
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if (okay || tmp->tm_isdst < 0)
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return t;
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return WRONG;
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}
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time_t
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mktime(
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struct tm * tmp
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)
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{
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return time1(tmp);
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}
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#endif /* !HAVE_MKTIME */
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#if !HAVE_TIMEGM
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time_t
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timegm(
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struct tm * tmp
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)
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{
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register time_t t;
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int okay;
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tmp->tm_isdst = 0;
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t = time2(tmp, &okay, 0);
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if (okay || tmp->tm_isdst < 0)
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return t;
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return WRONG;
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}
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#endif /* !HAVE_TIMEGM */
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