502 lines
14 KiB
C
502 lines
14 KiB
C
/* Convert struct partime into time_t. */
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/* Copyright 1992, 1993, 1994, 1995, 1997 Paul Eggert
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Distributed under license by the Free Software Foundation, Inc.
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This file is part of RCS.
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RCS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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RCS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with RCS; see the file COPYING.
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If not, write to the Free Software Foundation,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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Report problems and direct all questions to:
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rcs-bugs@cs.purdue.edu
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*/
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/* For maximum portability, use only localtime and gmtime.
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Make no assumptions about the time_t epoch or the range of time_t values.
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Avoid mktime because it's not universal and because there's no easy,
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portable way for mktime to yield the inverse of gmtime. */
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#if has_conf_h
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# include <conf.h>
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#else
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# if HAVE_CONFIG_H
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# include <config.h>
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# else
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# ifndef __STDC__
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# define const
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# endif
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# endif
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/* MIPS RISCOS4.52 defines time_t in <sys/types.h> not <time.h>. */
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# include <sys/types.h>
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# if HAVE_LIMITS_H
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# include <limits.h>
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# endif
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# ifndef LONG_MIN
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# define LONG_MIN (-1-2147483647L)
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# endif
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# if STDC_HEADERS
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# include <stdlib.h>
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# endif
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# include <time.h>
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# ifdef __STDC__
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# define P(x) x
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# else
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# define P(x) ()
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# endif
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#endif
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#include <partime.h>
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#include <maketime.h>
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char const maket_id[] =
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"$Id: maketime.c,v 5.17 1999/08/29 11:12:37 eggert Exp $";
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static int isleap P ((int));
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static int month_days P ((struct tm const *));
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static time_t maketime P ((struct partime const *, time_t));
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/* Suppose A1 + B1 = SUM1, using 2's complement arithmetic ignoring overflow.
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Suppose A, B and SUM have the same respective signs as A1, B1, and SUM1.
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Then this yields nonzero if overflow occurred during the addition.
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Overflow occurs if A and B have the same sign, but A and SUM differ in sign.
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Use `^' to test whether signs differ, and `< 0' to isolate the sign. */
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#define overflow_sum_sign(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
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/* Quotient and remainder when dividing A by B,
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truncating towards minus infinity, where B is positive. */
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#define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
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#define MOD(a, b) ((a) % (b) + (b) * ((a) % (b) < 0))
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/* Number of days in 400 consecutive Gregorian years. */
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#define Y400_DAYS (365 * 400L + 100 - 4 + 1)
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/* Number of years to add to tm_year to get Gregorian year. */
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#define TM_YEAR_ORIGIN 1900
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static int
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isleap (y)
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int y;
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{
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return (y & 3) == 0 && (y % 100 != 0 || y % 400 == 0);
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}
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/* days in year before start of months 0-12 */
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static int const month_yday[] =
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{
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0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
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};
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/* Yield the number of days in TM's month. */
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static int
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month_days (tm)
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struct tm const *tm;
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{
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int m = tm->tm_mon;
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return (month_yday[m + 1] - month_yday[m]
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+ (m == 1 && isleap (tm->tm_year + TM_YEAR_ORIGIN)));
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}
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/* Convert UNIXTIME to struct tm form.
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Use gmtime if available and if !LOCALZONE, localtime otherwise. */
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struct tm *
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time2tm (unixtime, localzone)
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time_t unixtime;
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int localzone;
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{
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struct tm *tm;
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#ifdef TZ_is_unset
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static char const *TZ;
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if (!TZ && !(TZ = getenv ("TZ")))
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TZ_is_unset ("The TZ environment variable is not set; please set it to your timezone");
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#endif
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if (localzone || !(tm = gmtime (&unixtime)))
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tm = localtime (&unixtime);
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return tm;
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}
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/* Yield A - B, measured in seconds. */
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time_t
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difftm (a, b)
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struct tm const *a;
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struct tm const *b;
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{
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int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
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int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
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int ac = DIV (ay, 100);
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int bc = DIV (by, 100);
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int difference_in_day_of_year = a->tm_yday - b->tm_yday;
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int intervening_leap_days = (((ay >> 2) - (by >> 2))
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- (ac - bc)
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+ ((ac >> 2) - (bc >> 2)));
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time_t difference_in_years = ay - by;
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time_t difference_in_days
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= (difference_in_years * 365
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+ (intervening_leap_days + difference_in_day_of_year));
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return (((((difference_in_days * 24
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+ (a->tm_hour - b->tm_hour))
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* 60)
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+ (a->tm_min - b->tm_min))
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* 60)
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+ (a->tm_sec - b->tm_sec));
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}
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/* Adjust time T by adding SECONDS.
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The absolute value of SECONDS cannot exceed 59 * INT_MAX,
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and also cannot exceed one month's worth of seconds;
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this is enough to handle any POSIX or real-life daylight-saving offset.
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Adjust only T's year, mon, mday, hour, min and sec members;
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plus adjust wday if it is defined. */
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void
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adjzone (t, seconds)
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register struct tm *t;
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long seconds;
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{
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int days = 0;
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/* This code can be off by a second if SECONDS is not a multiple of 60,
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if T is local time, and if a leap second happens during this minute.
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But this bug has never occurred, and most likely will not ever occur.
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Liberia, the last country for which SECONDS % 60 was nonzero,
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switched to UTC in May 1972; the first leap second was in June 1972. */
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int leap_second = t->tm_sec == 60;
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long sec = seconds + (t->tm_sec - leap_second);
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if (sec < 0)
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{
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if ((t->tm_min -= (59 - sec) / 60) < 0
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&& (t->tm_hour -= (59 - t->tm_min) / 60) < 0)
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{
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days = - ((23 - t->tm_hour) / 24);
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if ((t->tm_mday += days) <= 0)
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{
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if (--t->tm_mon < 0)
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{
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--t->tm_year;
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t->tm_mon = 11;
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}
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t->tm_mday += month_days (t);
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}
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}
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}
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else
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{
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if (60 <= (t->tm_min += sec / 60)
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&& (24 <= (t->tm_hour += t->tm_min / 60)))
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{
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days = t->tm_hour / 24;
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if (month_days (t) < (t->tm_mday += days))
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{
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if (11 < ++t->tm_mon)
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{
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++t->tm_year;
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t->tm_mon = 0;
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}
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t->tm_mday = 1;
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}
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}
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}
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if (TM_DEFINED (t->tm_wday))
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t->tm_wday = MOD (t->tm_wday + days, 7);
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t->tm_hour = MOD (t->tm_hour, 24);
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t->tm_min = MOD (t->tm_min, 60);
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t->tm_sec = (int) MOD (sec, 60) + leap_second;
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}
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/* Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
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Use only TM's year, mon, mday, hour, min, and sec members.
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Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
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Yield -1 on failure (e.g. a member out of range).
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POSIX 1003.1 doesn't allow leap seconds, but some implementations
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have them anyway, so allow them if localtime/gmtime does. */
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time_t
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tm2time (tm, localzone)
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struct tm *tm;
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int localzone;
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{
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/* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
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static time_t t_cache[2];
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static struct tm tm_cache[2];
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time_t d, gt;
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struct tm const *gtm;
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/* The maximum number of iterations should be enough to handle any
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combinations of leap seconds, time zone rule changes, and solar time.
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4 is probably enough; we use a bigger number just to be safe. */
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int remaining_tries = 8;
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/* Avoid subscript errors. */
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if (12 <= (unsigned) tm->tm_mon)
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return -1;
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tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
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- (tm->tm_mon < 2 || !isleap (tm->tm_year + TM_YEAR_ORIGIN));
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/* Make a first guess. */
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gt = t_cache[localzone];
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gtm = gt ? &tm_cache[localzone] : time2tm (gt, localzone);
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/* Repeatedly use the error from the guess to improve the guess. */
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while ((d = difftm (tm, gtm)) != 0)
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{
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if (--remaining_tries == 0)
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return -1;
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gt += d;
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gtm = time2tm (gt, localzone);
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}
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/* Check that the guess actually matches;
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overflow can cause difftm to yield 0 even on differing times,
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or tm may have members out of range (e.g. bad leap seconds). */
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#define TM_DIFFER(a,b) \
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( \
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((a)->tm_year ^ (b)->tm_year) | \
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((a)->tm_mon ^ (b)->tm_mon) | \
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((a)->tm_mday ^ (b)->tm_mday) | \
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((a)->tm_hour ^ (b)->tm_hour) | \
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((a)->tm_min ^ (b)->tm_min) | \
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((a)->tm_sec ^ (b)->tm_sec) \
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)
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if (TM_DIFFER (tm, gtm))
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{
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/* If gt is a leap second, try gt+1; if it is one greater than
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a leap second, try gt-1; otherwise, it doesn't matter.
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Leap seconds always fall at month end. */
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int yd = tm->tm_year - gtm->tm_year;
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gt += yd + (yd ? 0 : tm->tm_mon - gtm->tm_mon);
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gtm = time2tm (gt, localzone);
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if (TM_DIFFER (tm, gtm))
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return -1;
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}
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t_cache[localzone] = gt;
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tm_cache[localzone] = *gtm;
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tm->tm_wday = gtm->tm_wday;
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return gt;
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}
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/* Check *PT and convert it to time_t.
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If it is incompletely specified, use DEFAULT_TIME to fill it out.
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Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
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Yield -1 on failure.
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ISO 8601 day-of-year and week numbers are not yet supported. */
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static time_t
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maketime (pt, default_time)
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struct partime const *pt;
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time_t default_time;
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{
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int localzone, wday, year;
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struct tm tm;
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struct tm *tm0 = 0;
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time_t r;
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int use_ordinal_day;
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tm0 = 0; /* Keep gcc -Wall happy. */
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localzone = pt->zone == TM_LOCAL_ZONE;
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tm = pt->tm;
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year = tm.tm_year;
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wday = tm.tm_wday;
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use_ordinal_day = (!TM_DEFINED (tm.tm_mday)
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&& TM_DEFINED (wday) && TM_DEFINED (pt->wday_ordinal));
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if (use_ordinal_day || TM_DEFINED (pt->ymodulus) || !TM_DEFINED (year))
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{
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/* Get tm corresponding to default time. */
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tm0 = time2tm (default_time, localzone);
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if (!localzone)
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adjzone (tm0, pt->zone);
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}
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if (use_ordinal_day)
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tm.tm_mday = (tm0->tm_mday
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+ ((wday - tm0->tm_wday + 7) % 7
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+ 7 * (pt->wday_ordinal - (pt->wday_ordinal != 0))));
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if (TM_DEFINED (pt->ymodulus))
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{
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/* Yield a year closest to the default that has the given modulus. */
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int year0 = tm0->tm_year + TM_YEAR_ORIGIN;
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int y0 = MOD (year0, pt->ymodulus);
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int d = 2 * (year - y0);
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year += (((year0 - y0) / pt->ymodulus
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+ (pt->ymodulus < d ? -1 : d < -pt->ymodulus))
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* pt->ymodulus);
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}
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else if (!TM_DEFINED (year))
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{
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/* Set default year, month, day from current time. */
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year = tm0->tm_year + TM_YEAR_ORIGIN;
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if (!TM_DEFINED (tm.tm_mon))
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{
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tm.tm_mon = tm0->tm_mon;
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if (!TM_DEFINED (tm.tm_mday))
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tm.tm_mday = tm0->tm_mday;
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}
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}
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/* Set remaining default fields to be their minimum values. */
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if (!TM_DEFINED (tm.tm_mon))
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tm.tm_mon = 0;
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if (!TM_DEFINED (tm.tm_mday))
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tm.tm_mday = 1;
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if (!TM_DEFINED (tm.tm_hour))
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tm.tm_hour = 0;
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if (!TM_DEFINED (tm.tm_min))
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tm.tm_min = 0;
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if (!TM_DEFINED (tm.tm_sec))
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tm.tm_sec = 0;
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tm.tm_year = year - TM_YEAR_ORIGIN;
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if ((year < tm.tm_year) != (TM_YEAR_ORIGIN < 0))
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return -1;
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if (!localzone)
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{
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adjzone (&tm, -pt->zone);
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wday = tm.tm_wday;
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}
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/* Convert and fill in the rest of the tm. */
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r = tm2time (&tm, localzone);
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if (r == -1)
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return r;
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/* Check weekday. */
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if (TM_DEFINED (wday) && wday != tm.tm_wday)
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return -1;
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/* Add relative time, except for seconds.
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We handle seconds separately, at the end,
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so that leap seconds are handled properly. */
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if (pt->tmr.tm_year | pt->tmr.tm_mon | pt->tmr.tm_mday
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| pt->tmr.tm_hour | pt->tmr.tm_min)
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{
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int years = tm.tm_year + pt->tmr.tm_year;
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int mons = tm.tm_mon + pt->tmr.tm_mon;
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int mdays = tm.tm_mday + pt->tmr.tm_mday;
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int hours = tm.tm_hour + pt->tmr.tm_hour;
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int mins = tm.tm_min + pt->tmr.tm_min;
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int carried_hours = DIV (mins, 60);
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int hours1 = hours + carried_hours;
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int carried_days = DIV (hours1, 24);
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int mdays1 = mdays + carried_days;
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int mon0 = MOD (mons, 12);
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int carried_years0 = DIV (mons, 12);
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int year0 = years + carried_years0;
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int yday0 = (month_yday[mon0]
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- (mon0 < 2 || !isleap (year0 + TM_YEAR_ORIGIN)));
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int yday1 = yday0 + mdays1;
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int carried_years1 = DIV (yday1, Y400_DAYS) * 400;
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int year1 = year0 + carried_years1;
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int yday2 = MOD (yday1, Y400_DAYS);
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int leap;
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if (overflow_sum_sign (tm.tm_year, pt->tmr.tm_year, years)
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| overflow_sum_sign (tm.tm_mon, pt->tmr.tm_mon, mons)
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| overflow_sum_sign (tm.tm_mday, pt->tmr.tm_mday, mdays)
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| overflow_sum_sign (tm.tm_hour, pt->tmr.tm_hour, hours)
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| overflow_sum_sign (tm.tm_min, pt->tmr.tm_min, mins)
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| overflow_sum_sign (hours, carried_hours, hours1)
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| overflow_sum_sign (mdays, carried_days, mdays1)
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| overflow_sum_sign (years, carried_years0, year0)
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| overflow_sum_sign (yday0, mdays1, yday1)
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| overflow_sum_sign (year0, carried_years1, year1))
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return -1;
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for (;;)
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{
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int days_per_year = 365 + (leap = isleap (year1 + TM_YEAR_ORIGIN));
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if (yday2 < days_per_year)
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break;
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yday2 -= days_per_year;
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year1++;
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}
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tm.tm_year = year1;
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{
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int mon;
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for (mon = 11;
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(tm.tm_mday = (yday2 - month_yday[mon] + (mon < 2 || !leap))) <= 0;
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mon--)
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continue;
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tm.tm_mon = mon;
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}
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tm.tm_hour = MOD (hours1, 24);
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tm.tm_min = MOD (mins, 60);
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r = tm2time (&tm, localzone);
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if (r == -1)
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return r;
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}
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/* Add the seconds' part of relative time. */
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{
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time_t rs = r + pt->tmr.tm_sec;
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if ((pt->tmr.tm_sec < 0) != (rs < r))
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return -1;
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return rs;
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}
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}
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/* Parse a free-format date in *SOURCE, yielding a Unix format time.
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Update *SOURCE to point to the first character after the date.
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If *SOURCE is missing some information, take defaults from
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DEFAULT_TIME and DEFAULT_ZONE. *SOURCE may even be the empty
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string or an immediately invalid string, in which case the default
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time and zone is used.
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Return (time_t) -1 if the time is invalid or cannot be represented. */
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time_t
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str2time (source, default_time, default_zone)
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char const **source;
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time_t default_time;
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long default_zone;
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{
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struct partime pt;
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*source = partime (*source, &pt);
|
|
if (pt.zone == TM_UNDEFINED_ZONE)
|
|
pt.zone = default_zone;
|
|
return maketime (&pt, default_time);
|
|
}
|
|
|
|
#ifdef TEST
|
|
#include <stdio.h>
|
|
int
|
|
main (argc, argv)
|
|
int argc;
|
|
char **argv;
|
|
{
|
|
time_t default_time = time ((time_t *) 0);
|
|
long default_zone = argv[1] ? atol (argv[1]) : TM_LOCAL_ZONE;
|
|
char buf[1000];
|
|
while (fgets (buf, sizeof (buf), stdin))
|
|
{
|
|
char const *p = buf;
|
|
time_t t = str2time (&p, default_time, default_zone);
|
|
printf ("`%.*s' -> %s",
|
|
(int) (p - buf - (p[0] == '\0' && p[-1] == '\n')), buf,
|
|
asctime ((argv[1] ? gmtime : localtime) (&t)));
|
|
}
|
|
return 0;
|
|
}
|
|
#endif
|