1 /* Convert struct partime into time_t. */
3 /* Copyright 1992, 1993, 1994, 1995 Paul Eggert
4 Distributed under license by the Free Software Foundation, Inc.
6 This file is part of RCS.
8 RCS is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 RCS is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with RCS; see the file COPYING.
20 If not, write to the Free Software Foundation,
21 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
23 Report problems and direct all questions to:
25 rcs-bugs@cs.purdue.edu
29 * $FreeBSD: src/gnu/usr.bin/rcs/lib/maketime.c,v 1.7 1999/08/27 23:36:43 peter Exp $
30 * $DragonFly: src/gnu/usr.bin/rcs/lib/maketime.c,v 1.2 2003/06/17 04:25:47 dillon Exp $
49 static int isleap P((int));
50 static int month_days P((struct tm const*));
51 static time_t maketime P((struct partime const*,time_t));
54 * For maximum portability, use only localtime and gmtime.
55 * Make no assumptions about the time_t epoch or the range of time_t values.
56 * Avoid mktime because it's not universal and because there's no easy,
57 * portable way for mktime to yield the inverse of gmtime.
60 #define TM_YEAR_ORIGIN 1900
66 return (y&3) == 0 && (y%100 != 0 || y%400 == 0);
69 static int const month_yday[] = {
70 /* days in year before start of months 0-12 */
71 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
74 /* Yield the number of days in TM's month. */
80 return month_yday[m+1] - month_yday[m]
81 + (m==1 && isleap(tm->tm_year + TM_YEAR_ORIGIN));
85 * Convert UNIXTIME to struct tm form.
86 * Use gmtime if available and if !LOCALZONE, localtime otherwise.
89 time2tm(unixtime, localzone)
95 static char const *TZ;
96 if (!TZ && !(TZ = getenv("TZ")))
97 faterror("The TZ environment variable is not set; please set it to your timezone");
99 if (localzone || !(tm = gmtime(&unixtime)))
100 tm = localtime(&unixtime);
104 /* Yield A - B, measured in seconds. */
107 struct tm const *a, *b;
109 int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
110 int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
111 int difference_in_day_of_year = a->tm_yday - b->tm_yday;
112 int intervening_leap_days = (
113 ((ay >> 2) - (by >> 2))
115 + ((ay/100 >> 2) - (by/100 >> 2))
117 time_t difference_in_years = ay - by;
118 time_t difference_in_days = (
119 difference_in_years*365
120 + (intervening_leap_days + difference_in_day_of_year)
125 24*difference_in_days
126 + (a->tm_hour - b->tm_hour)
127 )*60 + (a->tm_min - b->tm_min)
128 )*60 + (a->tm_sec - b->tm_sec);
132 * Adjust time T by adding SECONDS. SECONDS must be at most 24 hours' worth.
133 * Adjust only T's year, mon, mday, hour, min and sec members;
134 * plus adjust wday if it is defined.
138 register struct tm *t;
142 * This code can be off by a second if SECONDS is not a multiple of 60,
143 * if T is local time, and if a leap second happens during this minute.
144 * But this bug has never occurred, and most likely will not ever occur.
145 * Liberia, the last country for which SECONDS % 60 was nonzero,
146 * switched to UTC in May 1972; the first leap second was in June 1972.
148 int leap_second = t->tm_sec == 60;
149 long sec = seconds + (t->tm_sec - leap_second);
151 if ((t->tm_min -= (59-sec)/60) < 0) {
152 if ((t->tm_hour -= (59-t->tm_min)/60) < 0) {
154 if (TM_DEFINED(t->tm_wday) && --t->tm_wday < 0)
156 if (--t->tm_mday <= 0) {
157 if (--t->tm_mon < 0) {
161 t->tm_mday = month_days(t);
164 t->tm_min += 24 * 60;
166 sec += 24L * 60 * 60;
168 if (60 <= (t->tm_min += sec/60))
169 if (24 <= (t->tm_hour += t->tm_min/60)) {
171 if (TM_DEFINED(t->tm_wday) && ++t->tm_wday == 7)
173 if (month_days(t) < ++t->tm_mday) {
174 if (11 < ++t->tm_mon) {
182 t->tm_sec = (int) (sec%60) + leap_second;
186 * Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
187 * Use only TM's year, mon, mday, hour, min, and sec members.
188 * Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
189 * Yield -1 on failure (e.g. a member out of range).
190 * Posix 1003.1-1990 doesn't allow leap seconds, but some implementations
191 * have them anyway, so allow them if localtime/gmtime does.
194 tm2time(tm, localzone)
198 /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
199 static time_t t_cache[2];
200 static struct tm tm_cache[2];
203 struct tm const *gtm;
205 * The maximum number of iterations should be enough to handle any
206 * combinations of leap seconds, time zone rule changes, and solar time.
207 * 4 is probably enough; we use a bigger number just to be safe.
209 int remaining_tries = 8;
211 /* Avoid subscript errors. */
212 if (12 <= (unsigned)tm->tm_mon)
215 tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
216 - (tm->tm_mon<2 || ! isleap(tm->tm_year + TM_YEAR_ORIGIN));
218 /* Make a first guess. */
219 gt = t_cache[localzone];
220 gtm = gt ? &tm_cache[localzone] : time2tm(gt,localzone);
222 /* Repeatedly use the error from the guess to improve the guess. */
223 while ((d = difftm(tm, gtm)) != 0) {
224 if (--remaining_tries == 0)
227 gtm = time2tm(gt,localzone);
229 t_cache[localzone] = gt;
230 tm_cache[localzone] = *gtm;
233 * Check that the guess actually matches;
234 * overflow can cause difftm to yield 0 even on differing times,
235 * or tm may have members out of range (e.g. bad leap seconds).
237 if ( (tm->tm_year ^ gtm->tm_year)
238 | (tm->tm_mon ^ gtm->tm_mon)
239 | (tm->tm_mday ^ gtm->tm_mday)
240 | (tm->tm_hour ^ gtm->tm_hour)
241 | (tm->tm_min ^ gtm->tm_min)
242 | (tm->tm_sec ^ gtm->tm_sec))
245 tm->tm_wday = gtm->tm_wday;
250 * Check *PT and convert it to time_t.
251 * If it is incompletely specified, use DEFAULT_TIME to fill it out.
252 * Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
253 * Yield -1 on failure.
254 * ISO 8601 day-of-year and week numbers are not yet supported.
257 maketime(pt, default_time)
258 struct partime const *pt;
266 tm0 = 0; /* Keep gcc -Wall happy. */
267 localzone = pt->zone==TM_LOCAL_ZONE;
271 if (TM_DEFINED(pt->ymodulus) || !TM_DEFINED(tm.tm_year)) {
272 /* Get tm corresponding to current time. */
273 tm0 = time2tm(default_time, localzone);
275 adjzone(tm0, pt->zone);
278 if (TM_DEFINED(pt->ymodulus))
280 (tm0->tm_year + TM_YEAR_ORIGIN)/pt->ymodulus * pt->ymodulus;
281 else if (!TM_DEFINED(tm.tm_year)) {
282 /* Set default year, month, day from current time. */
283 tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN;
284 if (!TM_DEFINED(tm.tm_mon)) {
285 tm.tm_mon = tm0->tm_mon;
286 if (!TM_DEFINED(tm.tm_mday))
287 tm.tm_mday = tm0->tm_mday;
291 /* Convert from partime year (Gregorian) to Posix year. */
292 tm.tm_year -= TM_YEAR_ORIGIN;
294 /* Set remaining default fields to be their minimum values. */
295 if (!TM_DEFINED(tm.tm_mon)) tm.tm_mon = 0;
296 if (!TM_DEFINED(tm.tm_mday)) tm.tm_mday = 1;
297 if (!TM_DEFINED(tm.tm_hour)) tm.tm_hour = 0;
298 if (!TM_DEFINED(tm.tm_min)) tm.tm_min = 0;
299 if (!TM_DEFINED(tm.tm_sec)) tm.tm_sec = 0;
302 adjzone(&tm, -pt->zone);
305 /* Convert and fill in the rest of the tm. */
306 r = tm2time(&tm, localzone);
309 if (r != -1 && TM_DEFINED(wday) && wday != tm.tm_wday)
315 /* Parse a free-format date in SOURCE, yielding a Unix format time. */
317 str2time(source, default_time, default_zone)
324 if (*partime(source, &pt))
326 if (pt.zone == TM_UNDEFINED_ZONE)
327 pt.zone = default_zone;
328 return maketime(&pt, default_time);
334 main(argc, argv) int argc; char **argv;
336 time_t default_time = time((time_t *)0);
337 long default_zone = argv[1] ? atol(argv[1]) : 0;
339 while (fgets(buf, 1000, stdin)) {
340 time_t t = str2time(buf, default_time, default_zone);
341 printf("%s", asctime(gmtime(&t)));