ref: 71a1d11a81faba020649408e8c9eaeb10095a341
dir: /sys/src/ape/cmd/patch/maketime.c/
/* Convert struct partime into time_t. */ /* Copyright 1992, 1993, 1994, 1995, 1997 Paul Eggert Distributed under license by the Free Software Foundation, Inc. This file is part of RCS. RCS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. RCS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with RCS; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. Report problems and direct all questions to: [email protected] */ #if has_conf_h # include <conf.h> #else # if HAVE_CONFIG_H # include <config.h> # else # ifndef __STDC__ # define const # endif # endif /* MIPS RISCOS4.52 defines time_t in <sys/types.h> not <time.h>. */ # include <sys/types.h> # if HAVE_LIMITS_H # include <limits.h> # endif # ifndef LONG_MIN # define LONG_MIN (-1-2147483647L) # endif # if STDC_HEADERS # include <stdlib.h> # endif # include <time.h> # ifdef __STDC__ # define P(x) x # else # define P(x) () # endif #endif #include <partime.h> #include <maketime.h> char const maketId[] = "$Id: maketime.c,v 5.15 1997/06/17 16:54:36 eggert Exp $"; static int isleap P ((int)); static int month_days P ((struct tm const *)); static time_t maketime P ((struct partime const *, time_t)); /* For maximum portability, use only localtime and gmtime. Make no assumptions about the time_t epoch or the range of time_t values. Avoid mktime because it's not universal and because there's no easy, portable way for mktime to yield the inverse of gmtime. */ #define TM_YEAR_ORIGIN 1900 static int isleap (y) int y; { return (y & 3) == 0 && (y % 100 != 0 || y % 400 == 0); } /* days in year before start of months 0-12 */ static int const month_yday[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }; /* Yield the number of days in TM's month. */ static int month_days (tm) struct tm const *tm; { int m = tm->tm_mon; return (month_yday[m + 1] - month_yday[m] + (m == 1 && isleap (tm->tm_year + TM_YEAR_ORIGIN))); } /* Convert UNIXTIME to struct tm form. Use gmtime if available and if !LOCALZONE, localtime otherwise. */ struct tm * time2tm (unixtime, localzone) time_t unixtime; int localzone; { struct tm *tm; #ifdef TZ_is_unset static char const *TZ; if (!TZ && !(TZ = getenv ("TZ"))) TZ_is_unset ("The TZ environment variable is not set; please set it to your timezone"); #endif if (localzone || !(tm = gmtime (&unixtime))) tm = localtime (&unixtime); return tm; } /* Yield A - B, measured in seconds. */ time_t difftm (a, b) struct tm const *a; struct tm const *b; { int ay = a->tm_year + (TM_YEAR_ORIGIN - 1); int by = b->tm_year + (TM_YEAR_ORIGIN - 1); int ac = ay / 100 - (ay % 100 < 0); int bc = by / 100 - (by % 100 < 0); int difference_in_day_of_year = a->tm_yday - b->tm_yday; int intervening_leap_days = (((ay >> 2) - (by >> 2)) - (ac - bc) + ((ac >> 2) - (bc >> 2))); time_t difference_in_years = ay - by; time_t difference_in_days = (difference_in_years * 365 + (intervening_leap_days + difference_in_day_of_year)); return (((((difference_in_days * 24 + (a->tm_hour - b->tm_hour)) * 60) + (a->tm_min - b->tm_min)) * 60) + (a->tm_sec - b->tm_sec)); } /* * Adjust time T by adding SECONDS. SECONDS must be at most 24 hours' worth. * Adjust only T's year, mon, mday, hour, min and sec members; * plus adjust wday if it is defined. */ void adjzone (t, seconds) register struct tm *t; long seconds; { /* * This code can be off by a second if SECONDS is not a multiple of 60, * if T is local time, and if a leap second happens during this minute. * But this bug has never occurred, and most likely will not ever occur. * Liberia, the last country for which SECONDS % 60 was nonzero, * switched to UTC in May 1972; the first leap second was in June 1972. */ int leap_second = t->tm_sec == 60; long sec = seconds + (t->tm_sec - leap_second); if (sec < 0) { if ((t->tm_min -= (59 - sec) / 60) < 0) { if ((t->tm_hour -= (59 - t->tm_min) / 60) < 0) { t->tm_hour += 24; if (TM_DEFINED (t->tm_wday) && --t->tm_wday < 0) t->tm_wday = 6; if (--t->tm_mday <= 0) { if (--t->tm_mon < 0) { --t->tm_year; t->tm_mon = 11; } t->tm_mday = month_days (t); } } t->tm_min += 24 * 60; } sec += 24L * 60 * 60; } else if (60 <= (t->tm_min += sec / 60)) if (24 <= (t->tm_hour += t->tm_min / 60)) { t->tm_hour -= 24; if (TM_DEFINED (t->tm_wday) && ++t->tm_wday == 7) t->tm_wday = 0; if (month_days (t) < ++t->tm_mday) { if (11 < ++t->tm_mon) { ++t->tm_year; t->tm_mon = 0; } t->tm_mday = 1; } } t->tm_min %= 60; t->tm_sec = (int) (sec % 60) + leap_second; } /* * Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise. * Use only TM's year, mon, mday, hour, min, and sec members. * Ignore TM's old tm_yday and tm_wday, but fill in their correct values. * Yield -1 on failure (e.g. a member out of range). * Posix 1003.1-1990 doesn't allow leap seconds, but some implementations * have them anyway, so allow them if localtime/gmtime does. */ time_t tm2time (tm, localzone) struct tm *tm; int localzone; { /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */ static time_t t_cache[2]; static struct tm tm_cache[2]; time_t d, gt; struct tm const *gtm; /* * The maximum number of iterations should be enough to handle any * combinations of leap seconds, time zone rule changes, and solar time. * 4 is probably enough; we use a bigger number just to be safe. */ int remaining_tries = 8; /* Avoid subscript errors. */ if (12 <= (unsigned) tm->tm_mon) return -1; tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday - (tm->tm_mon < 2 || !isleap (tm->tm_year + TM_YEAR_ORIGIN)); /* Make a first guess. */ gt = t_cache[localzone]; gtm = gt ? &tm_cache[localzone] : time2tm (gt, localzone); /* Repeatedly use the error from the guess to improve the guess. */ while ((d = difftm (tm, gtm)) != 0) { if (--remaining_tries == 0) return -1; gt += d; gtm = time2tm (gt, localzone); } /* * Check that the guess actually matches; * overflow can cause difftm to yield 0 even on differing times, * or tm may have members out of range (e.g. bad leap seconds). */ #define TM_DIFFER(a,b) \ ( \ ((a)->tm_year ^ (b)->tm_year) | \ ((a)->tm_mon ^ (b)->tm_mon) | \ ((a)->tm_mday ^ (b)->tm_mday) | \ ((a)->tm_hour ^ (b)->tm_hour) | \ ((a)->tm_min ^ (b)->tm_min) | \ ((a)->tm_sec ^ (b)->tm_sec) \ ) if (TM_DIFFER (tm, gtm)) { /* * If gt is a leap second, try gt+1; if it is one greater than * a leap second, try gt-1; otherwise, it doesn't matter. * Leap seconds always fall at month end. */ int yd = tm->tm_year - gtm->tm_year; gt += yd + (yd ? 0 : tm->tm_mon - gtm->tm_mon); gtm = time2tm (gt, localzone); if (TM_DIFFER (tm, gtm)) return -1; } t_cache[localzone] = gt; tm_cache[localzone] = *gtm; tm->tm_wday = gtm->tm_wday; return gt; } /* * Check *PT and convert it to time_t. * If it is incompletely specified, use DEFAULT_TIME to fill it out. * Use localtime if PT->zone is the special value TM_LOCAL_ZONE. * Yield -1 on failure. * ISO 8601 day-of-year and week numbers are not yet supported. */ static time_t maketime (pt, default_time) struct partime const *pt; time_t default_time; { int localzone, wday; struct tm tm; struct tm *tm0 = 0; time_t r; tm0 = 0; /* Keep gcc -Wall happy. */ localzone = pt->zone == TM_LOCAL_ZONE; tm = pt->tm; if (TM_DEFINED (pt->ymodulus) || !TM_DEFINED (tm.tm_year)) { /* Get tm corresponding to default time. */ tm0 = time2tm (default_time, localzone); if (!localzone) adjzone (tm0, pt->zone); } if (TM_DEFINED (pt->ymodulus)) tm.tm_year += (tm0->tm_year + TM_YEAR_ORIGIN) / pt->ymodulus * pt->ymodulus; else if (!TM_DEFINED (tm.tm_year)) { /* Set default year, month, day from current time. */ tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN; if (!TM_DEFINED (tm.tm_mon)) { tm.tm_mon = tm0->tm_mon; if (!TM_DEFINED (tm.tm_mday)) tm.tm_mday = tm0->tm_mday; } } /* Convert from partime year (Gregorian) to Posix year. */ tm.tm_year -= TM_YEAR_ORIGIN; /* Set remaining default fields to be their minimum values. */ if (!TM_DEFINED (tm.tm_mon)) tm.tm_mon = 0; if (!TM_DEFINED (tm.tm_mday)) tm.tm_mday = 1; if (!TM_DEFINED (tm.tm_hour)) tm.tm_hour = 0; if (!TM_DEFINED (tm.tm_min)) tm.tm_min = 0; if (!TM_DEFINED (tm.tm_sec)) tm.tm_sec = 0; if (!localzone) adjzone (&tm, -pt->zone); wday = tm.tm_wday; /* Convert and fill in the rest of the tm. */ r = tm2time (&tm, localzone); /* Check weekday. */ if (r != -1 && TM_DEFINED (wday) && wday != tm.tm_wday) return -1; return r; } /* Parse a free-format date in SOURCE, yielding a Unix format time. */ time_t str2time (source, default_time, default_zone) char const *source; time_t default_time; long default_zone; { struct partime pt; if (*partime (source, &pt)) return -1; if (pt.zone == TM_UNDEFINED_ZONE) pt.zone = default_zone; return maketime (&pt, default_time); } #if 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]) : 0; char buf[1000]; while (fgets (buf, sizeof (buf), stdin)) { time_t t = str2time (buf, default_time, default_zone); printf ("%s", asctime (gmtime (&t))); } return 0; } #endif