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_types.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
91 static 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
96 static 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
113 static void
normalize(int * tensptr,int * unitsptr,int base)114 normalize(
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
133 static struct tm *
mkdst(struct tm * tmp)134 mkdst(
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
148 static int
tmcomp(register struct tm * atmp,register struct tm * btmp)149 tmcomp(
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
181 static time_t
time2(struct tm * tmp,int * okayp,int usezn)182 time2(
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
262 NONEMPTY_TRANSLATION_UNIT
263 #endif /* !HAVE_MKTIME || !HAVE_TIMEGM */
264
265 #ifndef HAVE_MKTIME
266 static time_t
time1(struct tm * tmp)267 time1(
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
283 time_t
mktime(struct tm * tmp)284 mktime(
285 struct tm * tmp
286 )
287 {
288 return time1(tmp);
289 }
290 #endif /* !HAVE_MKTIME */
291
292 #ifdef WANT_TIMEGM
293 #ifndef HAVE_TIMEGM
294 time_t
timegm(struct tm * tmp)295 timegm(
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