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