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 "ntp_machine.h"
63
64 #if !defined(HAVE_MKTIME) || !defined(HAVE_TIMEGM)
65
66 #ifndef DSTMINUTES
67 #define DSTMINUTES 60
68 #endif
69
70 #define FALSE 0
71 #define TRUE 1
72
73 /* some constants from tzfile.h */
74 #define SECSPERMIN 60
75 #define MINSPERHOUR 60
76 #define HOURSPERDAY 24
77 #define DAYSPERWEEK 7
78 #define DAYSPERNYEAR 365
79 #define DAYSPERLYEAR 366
80 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
81 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY)
82 #define MONSPERYEAR 12
83 #define TM_YEAR_BASE 1900
84 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
85
86 static int mon_lengths[2][MONSPERYEAR] = {
87 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
88 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
89 };
90
91 static int year_lengths[2] = {
92 DAYSPERNYEAR, DAYSPERLYEAR
93 };
94
95 /*
96 ** Adapted from code provided by Robert Elz, who writes:
97 ** The "best" way to do mktime I think is based on an idea of Bob
98 ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now).
99 ** It does a binary search of the time_t space. Since time_t's are
100 ** just 32 bits, its a max of 32 iterations (even at 64 bits it
101 ** would still be very reasonable).
102 */
103
104 #ifndef WRONG
105 #define WRONG (-1)
106 #endif /* !defined WRONG */
107
108 static void
normalize(int * tensptr,int * unitsptr,int base)109 normalize(
110 int * tensptr,
111 int * unitsptr,
112 int base
113 )
114 {
115 if (*unitsptr >= base) {
116 *tensptr += *unitsptr / base;
117 *unitsptr %= base;
118 } else if (*unitsptr < 0) {
119 --*tensptr;
120 *unitsptr += base;
121 if (*unitsptr < 0) {
122 *tensptr -= 1 + (-*unitsptr) / base;
123 *unitsptr = base - (-*unitsptr) % base;
124 }
125 }
126 }
127
128 static struct tm *
mkdst(struct tm * tmp)129 mkdst(
130 struct tm * tmp
131 )
132 {
133 /* jds */
134 static struct tm tmbuf;
135
136 tmbuf = *tmp;
137 tmbuf.tm_isdst = 1;
138 tmbuf.tm_min += DSTMINUTES;
139 normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR);
140 return &tmbuf;
141 }
142
143 static int
tmcomp(register struct tm * atmp,register struct tm * btmp)144 tmcomp(
145 register struct tm * atmp,
146 register struct tm * btmp
147 )
148 {
149 register int result;
150
151 /* compare down to the same day */
152
153 if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
154 (result = (atmp->tm_mon - btmp->tm_mon)) == 0)
155 result = (atmp->tm_mday - btmp->tm_mday);
156
157 if(result != 0)
158 return result;
159
160 /* get rid of one-sided dst bias */
161
162 if(atmp->tm_isdst == 1 && !btmp->tm_isdst)
163 btmp = mkdst(btmp);
164 else if(btmp->tm_isdst == 1 && !atmp->tm_isdst)
165 atmp = mkdst(atmp);
166
167 /* compare the rest of the way */
168
169 if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
170 (result = (atmp->tm_min - btmp->tm_min)) == 0)
171 result = atmp->tm_sec - btmp->tm_sec;
172 return result;
173 }
174
175
176 static time_t
time2(struct tm * tmp,int * okayp,int usezn)177 time2(
178 struct tm * tmp,
179 int * okayp,
180 int usezn
181 )
182 {
183 register int dir;
184 register int bits;
185 register int i;
186 register int saved_seconds;
187 time_t t;
188 struct tm yourtm, mytm;
189
190 *okayp = FALSE;
191 yourtm = *tmp;
192 if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
193 normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
194 normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
195 normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
196 normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
197 while (yourtm.tm_mday <= 0) {
198 --yourtm.tm_year;
199 yourtm.tm_mday +=
200 year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
201 }
202 for ( ; ; ) {
203 i = mon_lengths[isleap(yourtm.tm_year +
204 TM_YEAR_BASE)][yourtm.tm_mon];
205 if (yourtm.tm_mday <= i)
206 break;
207 yourtm.tm_mday -= i;
208 if (++yourtm.tm_mon >= MONSPERYEAR) {
209 yourtm.tm_mon = 0;
210 ++yourtm.tm_year;
211 }
212 }
213 saved_seconds = yourtm.tm_sec;
214 yourtm.tm_sec = 0;
215 /*
216 ** Calculate the number of magnitude bits in a time_t
217 ** (this works regardless of whether time_t is
218 ** signed or unsigned, though lint complains if unsigned).
219 */
220 for (bits = 0, t = 1; t > 0; ++bits, t <<= 1)
221 ;
222 /*
223 ** If time_t is signed, then 0 is the median value,
224 ** if time_t is unsigned, then 1 << bits is median.
225 */
226 t = (t < 0) ? 0 : ((time_t) 1 << bits);
227 for ( ; ; ) {
228 if (usezn)
229 mytm = *localtime(&t);
230 else
231 mytm = *gmtime(&t);
232 dir = tmcomp(&mytm, &yourtm);
233 if (dir != 0) {
234 if (bits-- < 0)
235 return WRONG;
236 if (bits < 0)
237 --t;
238 else if (dir > 0)
239 t -= (time_t) 1 << bits;
240 else t += (time_t) 1 << bits;
241 continue;
242 }
243 if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
244 break;
245
246 return WRONG;
247 }
248 t += saved_seconds;
249 if (usezn)
250 *tmp = *localtime(&t);
251 else
252 *tmp = *gmtime(&t);
253 *okayp = TRUE;
254 return t;
255 }
256 #else
257 int mktime_bs;
258 #endif /* !HAVE_MKTIME || !HAVE_TIMEGM */
259
260 #ifndef HAVE_MKTIME
261 static time_t
time1(struct tm * tmp)262 time1(
263 struct tm * tmp
264 )
265 {
266 register time_t t;
267 int okay;
268
269 if (tmp->tm_isdst > 1)
270 tmp->tm_isdst = 1;
271 t = time2(tmp, &okay, 1);
272 if (okay || tmp->tm_isdst < 0)
273 return t;
274
275 return WRONG;
276 }
277
278 time_t
mktime(struct tm * tmp)279 mktime(
280 struct tm * tmp
281 )
282 {
283 return time1(tmp);
284 }
285 #endif /* !HAVE_MKTIME */
286
287 #ifndef HAVE_TIMEGM
288 time_t
timegm(struct tm * tmp)289 timegm(
290 struct tm * tmp
291 )
292 {
293 register time_t t;
294 int okay;
295
296 tmp->tm_isdst = 0;
297 t = time2(tmp, &okay, 0);
298 if (okay || tmp->tm_isdst < 0)
299 return t;
300
301 return WRONG;
302 }
303 #endif /* !HAVE_TIMEGM */
304