1/*
2 * Copyright (c) 1987, 1989 Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Arthur David Olson of the National Cancer Institute.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.  */
35
36/*static char *sccsid = "from: @(#)ctime.c	5.26 (Berkeley) 2/23/91";*/
37
38/*
39 * This implementation of mktime is lifted straight from the NetBSD (BSD 4.4)
40 * version.  I modified it slightly to divorce it from the internals of the
41 * ctime library.  Thus this version can't use details of the internal
42 * timezone state file to figure out strange unnormalized struct tm values,
43 * as might result from someone doing date math on the tm struct then passing
44 * it to mktime.
45 *
46 * It just does as well as it can at normalizing the tm input, then does a
47 * binary search of the time space using the system's localtime() function.
48 *
49 * The original binary search was defective in that it didn't consider the
50 * setting of tm_isdst when comparing tm values, causing the search to be
51 * flubbed for times near the dst/standard time changeover.  The original
52 * code seems to make up for this by grubbing through the timezone info
53 * whenever the binary search barfed.  Since I don't have that luxury in
54 * portable code, I have to take care of tm_isdst in the comparison routine.
55 * This requires knowing how many minutes offset dst is from standard time.
56 *
57 * So, if you live somewhere in the world where dst is not 60 minutes offset,
58 * and your vendor doesn't supply mktime(), you'll have to edit this variable
59 * by hand.  Sorry about that.
60 */
61
62#include <config.h>
63#include "ntp_machine.h"
64
65#if !defined(HAVE_MKTIME) || ( !defined(HAVE_TIMEGM) && defined(WANT_TIMEGM) )
66
67#if SIZEOF_TIME_T >= 8
68#error libntp supplied mktime()/timegm() do not support 64-bit time_t
69#endif
70
71#ifndef DSTMINUTES
72#define DSTMINUTES 60
73#endif
74
75#define FALSE 0
76#define TRUE 1
77
78/* some constants from tzfile.h */
79#define SECSPERMIN      60
80#define MINSPERHOUR     60
81#define HOURSPERDAY     24
82#define DAYSPERWEEK     7
83#define DAYSPERNYEAR    365
84#define DAYSPERLYEAR    366
85#define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
86#define SECSPERDAY      ((long) SECSPERHOUR * HOURSPERDAY)
87#define MONSPERYEAR     12
88#define TM_YEAR_BASE    1900
89#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
90
91static int	mon_lengths[2][MONSPERYEAR] = {
92	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
93	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
94};
95
96static int	year_lengths[2] = {
97	DAYSPERNYEAR, DAYSPERLYEAR
98};
99
100/*
101** Adapted from code provided by Robert Elz, who writes:
102**	The "best" way to do mktime I think is based on an idea of Bob
103**	Kridle's (so its said...) from a long time ago. (mtxinu!kridle now).
104**	It does a binary search of the time_t space.  Since time_t's are
105**	just 32 bits, its a max of 32 iterations (even at 64 bits it
106**	would still be very reasonable).
107*/
108
109#ifndef WRONG
110#define WRONG	(-1)
111#endif /* !defined WRONG */
112
113static void
114normalize(
115	int * tensptr,
116	int * unitsptr,
117	int	base
118	)
119{
120	if (*unitsptr >= base) {
121		*tensptr += *unitsptr / base;
122		*unitsptr %= base;
123	} else if (*unitsptr < 0) {
124		--*tensptr;
125		*unitsptr += base;
126		if (*unitsptr < 0) {
127			*tensptr -= 1 + (-*unitsptr) / base;
128			*unitsptr = base - (-*unitsptr) % base;
129		}
130	}
131}
132
133static struct tm *
134mkdst(
135	struct tm *	tmp
136	)
137{
138    /* jds */
139    static struct tm tmbuf;
140
141    tmbuf = *tmp;
142    tmbuf.tm_isdst = 1;
143    tmbuf.tm_min += DSTMINUTES;
144    normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR);
145    return &tmbuf;
146}
147
148static int
149tmcomp(
150	register struct tm * atmp,
151	register struct tm * btmp
152	)
153{
154	register int	result;
155
156	/* compare down to the same day */
157
158	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
159	    (result = (atmp->tm_mon - btmp->tm_mon)) == 0)
160	    result = (atmp->tm_mday - btmp->tm_mday);
161
162	if(result != 0)
163	    return result;
164
165	/* get rid of one-sided dst bias */
166
167	if(atmp->tm_isdst == 1 && !btmp->tm_isdst)
168	    btmp = mkdst(btmp);
169	else if(btmp->tm_isdst == 1 && !atmp->tm_isdst)
170	    atmp = mkdst(atmp);
171
172	/* compare the rest of the way */
173
174	if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
175	    (result = (atmp->tm_min - btmp->tm_min)) == 0)
176	    result = atmp->tm_sec - btmp->tm_sec;
177	return result;
178}
179
180
181static time_t
182time2(
183	struct tm *	tmp,
184	int * 		okayp,
185	int		usezn
186	)
187{
188	register int			dir;
189	register int			bits;
190	register int			i;
191	register int			saved_seconds;
192	time_t				t;
193	struct tm			yourtm, mytm;
194
195	*okayp = FALSE;
196	yourtm = *tmp;
197	if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
198		normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
199	normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
200	normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
201	normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
202	while (yourtm.tm_mday <= 0) {
203		--yourtm.tm_year;
204		yourtm.tm_mday +=
205			year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
206	}
207	for ( ; ; ) {
208		i = mon_lengths[isleap(yourtm.tm_year +
209			TM_YEAR_BASE)][yourtm.tm_mon];
210		if (yourtm.tm_mday <= i)
211			break;
212		yourtm.tm_mday -= i;
213		if (++yourtm.tm_mon >= MONSPERYEAR) {
214			yourtm.tm_mon = 0;
215			++yourtm.tm_year;
216		}
217	}
218	saved_seconds = yourtm.tm_sec;
219	yourtm.tm_sec = 0;
220	/*
221	** Calculate the number of magnitude bits in a time_t
222	** (this works regardless of whether time_t is
223	** signed or unsigned, though lint complains if unsigned).
224	*/
225	for (bits = 0, t = 1; t > 0; ++bits, t <<= 1)
226		;
227	/*
228	** If time_t is signed, then 0 is the median value,
229	** if time_t is unsigned, then 1 << bits is median.
230	*/
231	t = (t < 0) ? 0 : ((time_t) 1 << bits);
232	for ( ; ; ) {
233		if (usezn)
234			mytm = *localtime(&t);
235		else
236			mytm = *gmtime(&t);
237		dir = tmcomp(&mytm, &yourtm);
238		if (dir != 0) {
239			if (bits-- < 0)
240				return WRONG;
241			if (bits < 0)
242				--t;
243			else if (dir > 0)
244				t -= (time_t) 1 << bits;
245			else	t += (time_t) 1 << bits;
246			continue;
247		}
248		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
249			break;
250
251		return WRONG;
252	}
253	t += saved_seconds;
254	if (usezn)
255		*tmp = *localtime(&t);
256	else
257		*tmp = *gmtime(&t);
258	*okayp = TRUE;
259	return t;
260}
261#else
262int mktime_bs;
263#endif /* !HAVE_MKTIME || !HAVE_TIMEGM */
264
265#ifndef HAVE_MKTIME
266static time_t
267time1(
268	struct tm * tmp
269	)
270{
271	register time_t			t;
272	int				okay;
273
274	if (tmp->tm_isdst > 1)
275		tmp->tm_isdst = 1;
276	t = time2(tmp, &okay, 1);
277	if (okay || tmp->tm_isdst < 0)
278		return t;
279
280	return WRONG;
281}
282
283time_t
284mktime(
285	struct tm * tmp
286	)
287{
288	return time1(tmp);
289}
290#endif /* !HAVE_MKTIME */
291
292#ifdef WANT_TIMEGM
293#ifndef HAVE_TIMEGM
294time_t
295timegm(
296	struct tm * tmp
297	)
298{
299	register time_t			t;
300	int				okay;
301
302	tmp->tm_isdst = 0;
303	t = time2(tmp, &okay, 0);
304	if (okay || tmp->tm_isdst < 0)
305		return t;
306
307	return WRONG;
308}
309#endif /* !HAVE_TIMEGM */
310#endif /* WANT_TIMEGM */
311