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
48 static int isleap P((int));
49 static int month_days P((struct tm const*));
50 static time_t maketime P((struct partime const*,time_t));
53 * For maximum portability, use only localtime and gmtime.
54 * Make no assumptions about the time_t epoch or the range of time_t values.
55 * Avoid mktime because it's not universal and because there's no easy,
56 * portable way for mktime to yield the inverse of gmtime.
59 #define TM_YEAR_ORIGIN 1900
65 return (y&3) == 0 && (y%100 != 0 || y%400 == 0);
68 static int const month_yday[] = {
69 /* days in year before start of months 0-12 */
70 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
73 /* Yield the number of days in TM's month. */
79 return month_yday[m+1] - month_yday[m]
80 + (m==1 && isleap(tm->tm_year + TM_YEAR_ORIGIN));
84 * Convert UNIXTIME to struct tm form.
85 * Use gmtime if available and if !LOCALZONE, localtime otherwise.
88 time2tm(unixtime, localzone)
94 static char const *TZ;
95 if (!TZ && !(TZ = getenv("TZ")))
96 faterror("The TZ environment variable is not set; please set it to your timezone");
98 if (localzone || !(tm = gmtime(&unixtime)))
99 tm = localtime(&unixtime);
103 /* Yield A - B, measured in seconds. */
106 struct tm const *a, *b;
108 int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
109 int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
110 int difference_in_day_of_year = a->tm_yday - b->tm_yday;
111 int intervening_leap_days = (
112 ((ay >> 2) - (by >> 2))
114 + ((ay/100 >> 2) - (by/100 >> 2))
116 time_t difference_in_years = ay - by;
117 time_t difference_in_days = (
118 difference_in_years*365
119 + (intervening_leap_days + difference_in_day_of_year)
124 24*difference_in_days
125 + (a->tm_hour - b->tm_hour)
126 )*60 + (a->tm_min - b->tm_min)
127 )*60 + (a->tm_sec - b->tm_sec);
131 * Adjust time T by adding SECONDS. SECONDS must be at most 24 hours' worth.
132 * Adjust only T's year, mon, mday, hour, min and sec members;
133 * plus adjust wday if it is defined.
137 register struct tm *t;
141 * This code can be off by a second if SECONDS is not a multiple of 60,
142 * if T is local time, and if a leap second happens during this minute.
143 * But this bug has never occurred, and most likely will not ever occur.
144 * Liberia, the last country for which SECONDS % 60 was nonzero,
145 * switched to UTC in May 1972; the first leap second was in June 1972.
147 int leap_second = t->tm_sec == 60;
148 long sec = seconds + (t->tm_sec - leap_second);
150 if ((t->tm_min -= (59-sec)/60) < 0) {
151 if ((t->tm_hour -= (59-t->tm_min)/60) < 0) {
153 if (TM_DEFINED(t->tm_wday) && --t->tm_wday < 0)
155 if (--t->tm_mday <= 0) {
156 if (--t->tm_mon < 0) {
160 t->tm_mday = month_days(t);
163 t->tm_min += 24 * 60;
165 sec += 24L * 60 * 60;
167 if (60 <= (t->tm_min += sec/60))
168 if (24 <= (t->tm_hour += t->tm_min/60)) {
170 if (TM_DEFINED(t->tm_wday) && ++t->tm_wday == 7)
172 if (month_days(t) < ++t->tm_mday) {
173 if (11 < ++t->tm_mon) {
181 t->tm_sec = (int) (sec%60) + leap_second;
185 * Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
186 * Use only TM's year, mon, mday, hour, min, and sec members.
187 * Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
188 * Yield -1 on failure (e.g. a member out of range).
189 * Posix 1003.1-1990 doesn't allow leap seconds, but some implementations
190 * have them anyway, so allow them if localtime/gmtime does.
193 tm2time(tm, localzone)
197 /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
198 static time_t t_cache[2];
199 static struct tm tm_cache[2];
202 struct tm const *gtm;
204 * The maximum number of iterations should be enough to handle any
205 * combinations of leap seconds, time zone rule changes, and solar time.
206 * 4 is probably enough; we use a bigger number just to be safe.
208 int remaining_tries = 8;
210 /* Avoid subscript errors. */
211 if (12 <= (unsigned)tm->tm_mon)
214 tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
215 - (tm->tm_mon<2 || ! isleap(tm->tm_year + TM_YEAR_ORIGIN));
217 /* Make a first guess. */
218 gt = t_cache[localzone];
219 gtm = gt ? &tm_cache[localzone] : time2tm(gt,localzone);
221 /* Repeatedly use the error from the guess to improve the guess. */
222 while ((d = difftm(tm, gtm)) != 0) {
223 if (--remaining_tries == 0)
226 gtm = time2tm(gt,localzone);
228 t_cache[localzone] = gt;
229 tm_cache[localzone] = *gtm;
232 * Check that the guess actually matches;
233 * overflow can cause difftm to yield 0 even on differing times,
234 * or tm may have members out of range (e.g. bad leap seconds).
236 if ( (tm->tm_year ^ gtm->tm_year)
237 | (tm->tm_mon ^ gtm->tm_mon)
238 | (tm->tm_mday ^ gtm->tm_mday)
239 | (tm->tm_hour ^ gtm->tm_hour)
240 | (tm->tm_min ^ gtm->tm_min)
241 | (tm->tm_sec ^ gtm->tm_sec))
244 tm->tm_wday = gtm->tm_wday;
249 * Check *PT and convert it to time_t.
250 * If it is incompletely specified, use DEFAULT_TIME to fill it out.
251 * Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
252 * Yield -1 on failure.
253 * ISO 8601 day-of-year and week numbers are not yet supported.
256 maketime(pt, default_time)
257 struct partime const *pt;
265 tm0 = 0; /* Keep gcc -Wall happy. */
266 localzone = pt->zone==TM_LOCAL_ZONE;
270 if (TM_DEFINED(pt->ymodulus) || !TM_DEFINED(tm.tm_year)) {
271 /* Get tm corresponding to current time. */
272 tm0 = time2tm(default_time, localzone);
274 adjzone(tm0, pt->zone);
277 if (TM_DEFINED(pt->ymodulus))
279 (tm0->tm_year + TM_YEAR_ORIGIN)/pt->ymodulus * pt->ymodulus;
280 else if (!TM_DEFINED(tm.tm_year)) {
281 /* Set default year, month, day from current time. */
282 tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN;
283 if (!TM_DEFINED(tm.tm_mon)) {
284 tm.tm_mon = tm0->tm_mon;
285 if (!TM_DEFINED(tm.tm_mday))
286 tm.tm_mday = tm0->tm_mday;
290 /* Convert from partime year (Gregorian) to Posix year. */
291 tm.tm_year -= TM_YEAR_ORIGIN;
293 /* Set remaining default fields to be their minimum values. */
294 if (!TM_DEFINED(tm.tm_mon)) tm.tm_mon = 0;
295 if (!TM_DEFINED(tm.tm_mday)) tm.tm_mday = 1;
296 if (!TM_DEFINED(tm.tm_hour)) tm.tm_hour = 0;
297 if (!TM_DEFINED(tm.tm_min)) tm.tm_min = 0;
298 if (!TM_DEFINED(tm.tm_sec)) tm.tm_sec = 0;
301 adjzone(&tm, -pt->zone);
304 /* Convert and fill in the rest of the tm. */
305 r = tm2time(&tm, localzone);
308 if (r != -1 && TM_DEFINED(wday) && wday != tm.tm_wday)
314 /* Parse a free-format date in SOURCE, yielding a Unix format time. */
316 str2time(source, default_time, default_zone)
323 if (*partime(source, &pt))
325 if (pt.zone == TM_UNDEFINED_ZONE)
326 pt.zone = default_zone;
327 return maketime(&pt, default_time);
333 main(argc, argv) int argc; char **argv;
335 time_t default_time = time((time_t *)0);
336 long default_zone = argv[1] ? atol(argv[1]) : 0;
338 while (fgets(buf, 1000, stdin)) {
339 time_t t = str2time(buf, default_time, default_zone);
340 printf("%s", asctime(gmtime(&t)));