ref: d497eb2d2f88e3ae7fd7b2a4594aededed75468e
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:
rcs-bugs@cs.purdue.edu
*/
#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