1 /* $NetBSD: maketime.c,v 1.1.1.1 2016/01/14 03:05:06 christos Exp $ */
2
3 /* Convert struct partime into time_t. */
4
5 /* Copyright 1992, 1993, 1994, 1995 Paul Eggert
6 Distributed under license by the Free Software Foundation, Inc.
7
8 This file is part of RCS.
9
10 RCS is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
13 any later version.
14
15 RCS is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
19
20 You should have received a copy of the GNU General Public License
21 along with RCS; see the file COPYING.
22 If not, write to the Free Software Foundation,
23 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24
25 Report problems and direct all questions to:
26
27 rcs-bugs@cs.purdue.edu
28
29 */
30
31 #if has_conf_h
32 # include "conf.h"
33 #else
34 # ifdef __STDC__
35 # define P(x) x
36 # else
37 # define const
38 # define P(x) ()
39 # endif
40 # include <stdlib.h>
41 # include <time.h>
42 #endif
43
44 #include "partime.h"
45 #include "maketime.h"
46
47 char const maketId[]
48 = "Id: maketime.c,v 5.11 1995/06/16 06:19:24 eggert Exp ";
49
50 static int isleap P((int));
51 static int month_days P((struct tm const*));
52 static time_t maketime P((struct partime const*,time_t));
53
54 /*
55 * For maximum portability, use only localtime and gmtime.
56 * Make no assumptions about the time_t epoch or the range of time_t values.
57 * Avoid mktime because it's not universal and because there's no easy,
58 * portable way for mktime to yield the inverse of gmtime.
59 */
60
61 #define TM_YEAR_ORIGIN 1900
62
63 static int
isleap(y)64 isleap(y)
65 int y;
66 {
67 return (y&3) == 0 && (y%100 != 0 || y%400 == 0);
68 }
69
70 static int const month_yday[] = {
71 /* days in year before start of months 0-12 */
72 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
73 };
74
75 /* Yield the number of days in TM's month. */
76 static int
month_days(tm)77 month_days(tm)
78 struct tm const *tm;
79 {
80 int m = tm->tm_mon;
81 return month_yday[m+1] - month_yday[m]
82 + (m==1 && isleap(tm->tm_year + TM_YEAR_ORIGIN));
83 }
84
85 /*
86 * Convert UNIXTIME to struct tm form.
87 * Use gmtime if available and if !LOCALZONE, localtime otherwise.
88 */
89 struct tm *
time2tm(unixtime,localzone)90 time2tm(unixtime, localzone)
91 time_t unixtime;
92 int localzone;
93 {
94 struct tm *tm;
95 # if TZ_must_be_set
96 static char const *TZ;
97 if (!TZ && !(TZ = getenv("TZ")))
98 faterror("The TZ environment variable is not set; please set it to your timezone");
99 # endif
100 if (localzone || !(tm = gmtime(&unixtime)))
101 tm = localtime(&unixtime);
102 return tm;
103 }
104
105 /* Yield A - B, measured in seconds. */
106 time_t
difftm(a,b)107 difftm(a, b)
108 struct tm const *a, *b;
109 {
110 int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
111 int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
112 int difference_in_day_of_year = a->tm_yday - b->tm_yday;
113 int intervening_leap_days = (
114 ((ay >> 2) - (by >> 2))
115 - (ay/100 - by/100)
116 + ((ay/100 >> 2) - (by/100 >> 2))
117 );
118 time_t difference_in_years = ay - by;
119 time_t difference_in_days = (
120 difference_in_years*365
121 + (intervening_leap_days + difference_in_day_of_year)
122 );
123 return
124 (
125 (
126 24*difference_in_days
127 + (a->tm_hour - b->tm_hour)
128 )*60 + (a->tm_min - b->tm_min)
129 )*60 + (a->tm_sec - b->tm_sec);
130 }
131
132 /*
133 * Adjust time T by adding SECONDS. SECONDS must be at most 24 hours' worth.
134 * Adjust only T's year, mon, mday, hour, min and sec members;
135 * plus adjust wday if it is defined.
136 */
137 void
adjzone(t,seconds)138 adjzone(t, seconds)
139 register struct tm *t;
140 long seconds;
141 {
142 /*
143 * This code can be off by a second if SECONDS is not a multiple of 60,
144 * if T is local time, and if a leap second happens during this minute.
145 * But this bug has never occurred, and most likely will not ever occur.
146 * Liberia, the last country for which SECONDS % 60 was nonzero,
147 * switched to UTC in May 1972; the first leap second was in June 1972.
148 */
149 int leap_second = t->tm_sec == 60;
150 long sec = seconds + (t->tm_sec - leap_second);
151 if (sec < 0) {
152 if ((t->tm_min -= (59-sec)/60) < 0) {
153 if ((t->tm_hour -= (59-t->tm_min)/60) < 0) {
154 t->tm_hour += 24;
155 if (TM_DEFINED(t->tm_wday) && --t->tm_wday < 0)
156 t->tm_wday = 6;
157 if (--t->tm_mday <= 0) {
158 if (--t->tm_mon < 0) {
159 --t->tm_year;
160 t->tm_mon = 11;
161 }
162 t->tm_mday = month_days(t);
163 }
164 }
165 t->tm_min += 24 * 60;
166 }
167 sec += 24L * 60 * 60;
168 } else
169 if (60 <= (t->tm_min += sec/60))
170 if (24 <= (t->tm_hour += t->tm_min/60)) {
171 t->tm_hour -= 24;
172 if (TM_DEFINED(t->tm_wday) && ++t->tm_wday == 7)
173 t->tm_wday = 0;
174 if (month_days(t) < ++t->tm_mday) {
175 if (11 < ++t->tm_mon) {
176 ++t->tm_year;
177 t->tm_mon = 0;
178 }
179 t->tm_mday = 1;
180 }
181 }
182 t->tm_min %= 60;
183 t->tm_sec = (int) (sec%60) + leap_second;
184 }
185
186 /*
187 * Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
188 * Use only TM's year, mon, mday, hour, min, and sec members.
189 * Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
190 * Yield -1 on failure (e.g. a member out of range).
191 * Posix 1003.1-1990 doesn't allow leap seconds, but some implementations
192 * have them anyway, so allow them if localtime/gmtime does.
193 */
194 time_t
tm2time(tm,localzone)195 tm2time(tm, localzone)
196 struct tm *tm;
197 int localzone;
198 {
199 /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
200 static time_t t_cache[2];
201 static struct tm tm_cache[2];
202
203 time_t d, gt;
204 struct tm const *gtm;
205 /*
206 * The maximum number of iterations should be enough to handle any
207 * combinations of leap seconds, time zone rule changes, and solar time.
208 * 4 is probably enough; we use a bigger number just to be safe.
209 */
210 int remaining_tries = 8;
211
212 /* Avoid subscript errors. */
213 if (12 <= (unsigned)tm->tm_mon)
214 return -1;
215
216 tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
217 - (tm->tm_mon<2 || ! isleap(tm->tm_year + TM_YEAR_ORIGIN));
218
219 /* Make a first guess. */
220 gt = t_cache[localzone];
221 gtm = gt ? &tm_cache[localzone] : time2tm(gt,localzone);
222
223 /* Repeatedly use the error from the guess to improve the guess. */
224 while ((d = difftm(tm, gtm)) != 0) {
225 if (--remaining_tries == 0)
226 return -1;
227 gt += d;
228 gtm = time2tm(gt,localzone);
229 }
230 t_cache[localzone] = gt;
231 tm_cache[localzone] = *gtm;
232
233 /*
234 * Check that the guess actually matches;
235 * overflow can cause difftm to yield 0 even on differing times,
236 * or tm may have members out of range (e.g. bad leap seconds).
237 */
238 if ( (tm->tm_year ^ gtm->tm_year)
239 | (tm->tm_mon ^ gtm->tm_mon)
240 | (tm->tm_mday ^ gtm->tm_mday)
241 | (tm->tm_hour ^ gtm->tm_hour)
242 | (tm->tm_min ^ gtm->tm_min)
243 | (tm->tm_sec ^ gtm->tm_sec))
244 return -1;
245
246 tm->tm_wday = gtm->tm_wday;
247 return gt;
248 }
249
250 /*
251 * Check *PT and convert it to time_t.
252 * If it is incompletely specified, use DEFAULT_TIME to fill it out.
253 * Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
254 * Yield -1 on failure.
255 * ISO 8601 day-of-year and week numbers are not yet supported.
256 */
257 static time_t
maketime(pt,default_time)258 maketime(pt, default_time)
259 struct partime const *pt;
260 time_t default_time;
261 {
262 int localzone, wday;
263 struct tm tm;
264 struct tm *tm0 = 0;
265 time_t r;
266
267 tm0 = 0; /* Keep gcc -Wall happy. */
268 localzone = pt->zone==TM_LOCAL_ZONE;
269
270 tm = pt->tm;
271
272 if (TM_DEFINED(pt->ymodulus) || !TM_DEFINED(tm.tm_year)) {
273 /* Get tm corresponding to current time. */
274 tm0 = time2tm(default_time, localzone);
275 if (!localzone)
276 adjzone(tm0, pt->zone);
277 }
278
279 if (TM_DEFINED(pt->ymodulus))
280 tm.tm_year +=
281 (tm0->tm_year + TM_YEAR_ORIGIN)/pt->ymodulus * pt->ymodulus;
282 else if (!TM_DEFINED(tm.tm_year)) {
283 /* Set default year, month, day from current time. */
284 tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN;
285 if (!TM_DEFINED(tm.tm_mon)) {
286 tm.tm_mon = tm0->tm_mon;
287 if (!TM_DEFINED(tm.tm_mday))
288 tm.tm_mday = tm0->tm_mday;
289 }
290 }
291
292 /* Convert from partime year (Gregorian) to Posix year. */
293 tm.tm_year -= TM_YEAR_ORIGIN;
294
295 /* Set remaining default fields to be their minimum values. */
296 if (!TM_DEFINED(tm.tm_mon)) tm.tm_mon = 0;
297 if (!TM_DEFINED(tm.tm_mday)) tm.tm_mday = 1;
298 if (!TM_DEFINED(tm.tm_hour)) tm.tm_hour = 0;
299 if (!TM_DEFINED(tm.tm_min)) tm.tm_min = 0;
300 if (!TM_DEFINED(tm.tm_sec)) tm.tm_sec = 0;
301
302 if (!localzone)
303 adjzone(&tm, -pt->zone);
304 wday = tm.tm_wday;
305
306 /* Convert and fill in the rest of the tm. */
307 r = tm2time(&tm, localzone);
308
309 /* Check weekday. */
310 if (r != -1 && TM_DEFINED(wday) && wday != tm.tm_wday)
311 return -1;
312
313 return r;
314 }
315
316 /* Parse a free-format date in SOURCE, yielding a Unix format time. */
317 time_t
str2time(source,default_time,default_zone)318 str2time(source, default_time, default_zone)
319 char const *source;
320 time_t default_time;
321 long default_zone;
322 {
323 struct partime pt;
324
325 if (*partime(source, &pt))
326 return -1;
327 if (pt.zone == TM_UNDEFINED_ZONE)
328 pt.zone = default_zone;
329 return maketime(&pt, default_time);
330 }
331
332 #if TEST
333 #include <stdio.h>
334 int
main(argc,argv)335 main(argc, argv) int argc; char **argv;
336 {
337 time_t default_time = time((time_t *)0);
338 long default_zone = argv[1] ? atol(argv[1]) : 0;
339 char buf[1000];
340 while (gets(buf)) {
341 time_t t = str2time(buf, default_time, default_zone);
342 printf("%s", asctime(gmtime(&t)));
343 }
344 return 0;
345 }
346 #endif
347