nativelibc/time/datetime.c

/*	A part of the Native C Library for Windows NT
	Copyright 2026 Rivoreo

	This program 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 of the License, or (at
	your option) any later version.

	This program 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.
*/

/*
 * A part of this file comes from public domain source, so
 * clarified as of June 5, 1996 by Arthur David Olson.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <stdint.h>
#include <string.h>
#include <limits.h>
#include <time.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <float.h>
#include <stdio.h>
#include <windows.h>
#include <nt.h>

#define PCTS
#define USG_COMPAT

/* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
#define is_digit(c) ((unsigned)(c) - '0' <= 9)

#ifndef TYPE_BIT
#define TYPE_BIT(T) (sizeof(T) * CHAR_BIT)
#endif

#ifndef TYPE_SIGNED
#define TYPE_SIGNED(T) (((T)-1) < 0)
#endif

#ifndef TYPE_INTEGRAL
#define TYPE_INTEGRAL(T) (((T)0.5) != 0.5)
#endif

#ifndef YEARSPERREPEAT
#define YEARSPERREPEAT 400
#endif

#ifndef AVGSECSPERYEAR
#define AVGSECSPERYEAR 31556952L
#endif

#ifndef SECSPERREPEAT
#define SECSPERREPEAT ((int_fast64_t)YEARSPERREPEAT * (int_fast64_t)AVGSECSPERYEAR)
#endif

#ifndef SECSPERREPEAT_BITS
#define SECSPERREPEAT_BITS 34
#endif

#ifndef TZDIR
#define TZDIR "/SystemRoot/zoneinfo"
#endif

#ifndef TZDEFRULES
#define TZDEFRULES "posixrules"
#endif

#define	TZ_MAGIC	"TZif"

struct tzhead {
	char	tzh_magic[4];		/* TZ_MAGIC */
	char	tzh_version[1];		/* '\0' or '2' as of 2005 */
	char	tzh_reserved[15];	/* reserved--must be zero */
	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
	char	tzh_leapcnt[4];		/* coded number of leap seconds */
	char	tzh_timecnt[4];		/* coded number of transition times */
	char	tzh_typecnt[4];		/* coded number of local time types */
	char	tzh_charcnt[4];		/* coded number of abbr. chars */
};

#ifndef TZ_MAX_TIMES
#define TZ_MAX_TIMES 1200
#endif

#ifndef TZ_MAX_TYPES
#define TZ_MAX_TYPES 256 /* UINT8_MAX + 1 */
#endif

#ifndef TZ_MAX_CHARS
#define TZ_MAX_CHARS 50
#endif

#ifndef TZ_MAX_LEAPS
#define TZ_MAX_LEAPS 50
#endif

#define SECSPERMIN 60
#define MINSPERHOUR 60
#define HOURSPERDAY 24
#define DAYSPERWEEK 7
#define DAYSPERNYEAR 365
#define DAYSPERLYEAR 366
#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
#define SECSPERDAY ((long int)SECSPERHOUR * HOURSPERDAY)
#define MONSPERYEAR 12

#define TM_SUNDAY 0
#define TM_MONDAY 1
#define TM_TUESDAY 2
#define TM_WEDNESDAY 3
#define TM_THURSDAY 4
#define TM_FRIDAY 5
#define TM_SATURDAY 6
#define TM_JANUARY 0
#define TM_FEBRUARY 1
#define TM_MARCH 2
#define TM_APRIL 3
#define TM_MAY 4
#define TM_JUNE 5
#define TM_JULY 6
#define TM_AUGUST 7
#define TM_SEPTEMBER 8
#define TM_OCTOBER 9
#define TM_NOVEMBER 10
#define TM_DECEMBER 11
#define TM_YEAR_BASE 1900

#define EPOCH_YEAR 1970
#define EPOCH_WDAY TM_THURSDAY


#ifndef TZ_ABBR_MAX_LEN
#define TZ_ABBR_MAX_LEN	16
#endif /* !defined TZ_ABBR_MAX_LEN */

#ifndef TZ_ABBR_CHAR_SET
#define TZ_ABBR_CHAR_SET \
	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
#endif /* !defined TZ_ABBR_CHAR_SET */

#ifndef TZ_ABBR_ERR_CHAR
#define TZ_ABBR_ERR_CHAR	'_'
#endif /* !defined TZ_ABBR_ERR_CHAR */

#define _RWLOCK_RDLOCK(L)
#define _RWLOCK_WRLOCK(L)
#define _RWLOCK_UNLOCK(L)

#ifndef WILDABBR
/*
** Someone might make incorrect use of a time zone abbreviation:
**	1.	They might reference tzname[0] before calling tzset (explicitly
**		or implicitly).
**	2.	They might reference tzname[1] before calling tzset (explicitly
**		or implicitly).
**	3.	They might reference tzname[1] after setting to a time zone
**		in which Daylight Saving Time is never observed.
**	4.	They might reference tzname[0] after setting to a time zone
**		in which Standard Time is never observed.
**	5.	They might reference tm.TM_ZONE after calling offtime.
** What's best to do in the above cases is open to debate;
** for now, we just set things up so that in any of the five cases
** WILDABBR is used. Another possibility: initialize tzname[0] to the
** string "tzname[0] used before set", and similarly for the other cases.
** And another: initialize tzname[0] to "ERA", with an explanation in the
** manual page of what this "time zone abbreviation" means (doing this so
** that tzname[0] has the "normal" length of three characters).
*/
#define WILDABBR	"   "
#endif /* !defined WILDABBR */


#define GMT "UTC"

/*
** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
** We default to US rules as of 1999-08-17.
** POSIX 1003.1 section 8.1.1 says that the default DST rules are
** implementation dependent; for historical reasons, US rules are a
** common default.
*/
#ifndef TZDEFRULESTRING
#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
#endif

struct ttinfo {				/* time type information */
	long		tt_gmtoff;	/* UTC offset in seconds */
	int		tt_isdst;	/* used to set tm_isdst */
	int		tt_abbrind;	/* abbreviation list index */
	int		tt_ttisstd;	/* TRUE if transition is std time */
	int		tt_ttisgmt;	/* TRUE if transition is UTC */
};

struct lsinfo {				/* leap second information */
	time_t		ls_trans;	/* transition time */
	long		ls_corr;	/* correction to apply */
};

#define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))

#ifdef TZNAME_MAX
#define MY_TZNAME_MAX	TZNAME_MAX
#endif /* defined TZNAME_MAX */
#ifndef TZNAME_MAX
#define MY_TZNAME_MAX	255
#endif /* !defined TZNAME_MAX */

struct state {
	int		leapcnt;
	int		timecnt;
	int		typecnt;
	int		charcnt;
	int		goback;
	int		goahead;
	time_t		ats[TZ_MAX_TIMES];
	unsigned char	types[TZ_MAX_TIMES];
	struct ttinfo	ttis[TZ_MAX_TYPES];
	char		chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof GMT),
				(2 * (MY_TZNAME_MAX + 1)))];
	struct lsinfo	lsis[TZ_MAX_LEAPS];
};

struct rule {
	int		r_type;		/* type of rule--see below */
	int		r_day;		/* day number of rule */
	int		r_week;		/* week number of rule */
	int		r_mon;		/* month number of rule */
	long		r_time;		/* transition time of rule */
};

#define JULIAN_DAY		0	/* Jn - Julian day */
#define DAY_OF_YEAR		1	/* n - day of year */
#define MONTH_NTH_DAY_OF_WEEK	2	/* Mm.n.d - month, week, day of week */

static int		tzload(const char *, struct state *,int);
static struct tm *	gmtsub(const time_t *, long int, struct tm *);
static struct tm *	localsub(const time_t *, long int, struct tm *);

#ifdef ALL_STATE
static struct state *	lclptr;
static struct state *	gmtptr;
#else
static struct state	lclmem;
static struct state	gmtmem;
#define lclptr		(&lclmem)
#define gmtptr		(&gmtmem)
#endif

#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX 255
#endif

static char		lcl_TZname[TZ_STRLEN_MAX + 1];
static int		lcl_is_set;

char *			tzname[2] = { WILDABBR, WILDABBR };

#ifdef USG_COMPAT
long int		timezone = 0;
int			daylight = 0;
#endif /* defined USG_COMPAT */

#ifdef ALTZONE
time_t			altzone = 0;
#endif /* defined ALTZONE */

static const int	mon_lengths[2][MONSPERYEAR] = {
	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};

static const int	year_lengths[2] = {
	DAYSPERNYEAR, DAYSPERLYEAR
};

static int32_t detzcode(const char *const codep)
{
	int32_t	result;
	int	i;

	result = (codep[0] & 0x80) ? ~0 : 0;
	for (i = 0; i < 4; ++i) result = (result << 8) | (codep[i] & 0xff);
	return result;
}

static time_t detzcode64(const char *const codep)
{
	time_t	result;
	int	i;

	result = (codep[0] & 0x80) ?  (~(int_fast64_t) 0) : 0;
	for (i = 0; i < 8; ++i)
		result = result * 256 + (codep[i] & 0xff);
	return result;
}

/*
** Adapted from code provided by Robert Elz, who writes:
**	The "best" way to do mktime I think is based on an idea of Bob
**	Kridle's (so its said...) from a long time ago.
**	It does a binary search of the time_t space. Since time_t's are
**	just 32 bits, its a max of 32 iterations (even at 64 bits it
**	would still be very reasonable).
*/

#ifndef WRONG
#define WRONG	(-1)
#endif

static int typesequiv(const struct state *const sp, const int a, const int b)
{
	if(!sp) return 0;
	if(a < 0 || a >= sp->typecnt) return 0;
	if(b < 0 || b >= sp->typecnt) return 0;

	const struct ttinfo *ap = sp->ttis + a;
	const struct ttinfo *bp = sp->ttis + b;
	return ap->tt_gmtoff == bp->tt_gmtoff &&
		ap->tt_isdst == bp->tt_isdst &&
		ap->tt_ttisstd == bp->tt_ttisstd &&
		ap->tt_ttisgmt == bp->tt_ttisgmt &&
		strcmp(sp->chars + ap->tt_abbrind, sp->chars + bp->tt_abbrind) == 0;
}

/*
** Given a pointer into a time zone string, scan until a character that is not
** a valid character in a zone name is found. Return a pointer to that
** character.
*/
static const char *getzname(const char *strp)
{
	char	c;
	while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' && c != '+') ++strp;
	return strp;
}

/*
** Given a pointer into an extended time zone string, scan until the ending
** delimiter of the zone name is located. Return a pointer to the delimiter.
**
** As with getzname above, the legal character set is actually quite
** restricted, with other characters producing undefined results.
** We don't do any checking here; checking is done later in common-case code.
*/
static const char *getqzname(register const char *strp, const int delim)
{
	register int	c;
	while ((c = *strp) != '\0' && c != delim) ++strp;
	return strp;
}

/*
** Given a pointer into a time zone string, extract a number from that string.
** Check that the number is within a specified range; if it is not, return
** NULL.
** Otherwise, return a pointer to the first character not part of the number.
*/
static const char *getnum(const char *strp, int *const nump, const int min, const int max)
{
	char	c;
	int	num;

	if (strp == NULL || !is_digit(c = *strp))
		return NULL;
	num = 0;
	do {
		num = num * 10 + (c - '0');
		if (num > max) return NULL;	/* illegal value */
		c = *++strp;
	} while (is_digit(c));
	if (num < min) return NULL;		/* illegal value */
	*nump = num;
	return strp;
}

/*
** Given a pointer into a time zone string, extract a number of seconds,
** in hh[:mm[:ss]] form, from the string.
** If any error occurs, return NULL.
** Otherwise, return a pointer to the first character not part of the number
** of seconds.
*/
static const char *getsecs(const char *strp, long int *const secsp)
{
	int	num;

	/*
	** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
	** "M10.4.6/26", which does not conform to Posix,
	** but which specifies the equivalent of
	** ``02:00 on the first Sunday on or after 23 Oct''.
	*/
	strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
	if (strp == NULL)
		return NULL;
	*secsp = num * (long) SECSPERHOUR;
	if (*strp == ':') {
		++strp;
		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
		if (strp == NULL)
			return NULL;
		*secsp += num * SECSPERMIN;
		if (*strp == ':') {
			++strp;
			/* `SECSPERMIN' allows for leap seconds. */
			strp = getnum(strp, &num, 0, SECSPERMIN);
			if (strp == NULL)
				return NULL;
			*secsp += num;
		}
	}
	return strp;
}

/*
** Given a pointer into a time zone string, extract an offset, in
** [+-]hh[:mm[:ss]] form, from the string.
** If any error occurs, return NULL.
** Otherwise, return a pointer to the first character not part of the time.
*/
static const char *getoffset(const char *strp, long int *const offsetp)
{
	int	neg = 0;

	if (*strp == '-') {
		neg = 1;
		++strp;
	} else if (*strp == '+')
		++strp;
	strp = getsecs(strp, offsetp);
	if (strp == NULL)
		return NULL;		/* illegal time */
	if (neg)
		*offsetp = -*offsetp;
	return strp;
}

/*
** Given a pointer into a time zone string, extract a rule in the form
** date[/time]. See POSIX section 8 for the format of "date" and "time".
** If a valid rule is not found, return NULL.
** Otherwise, return a pointer to the first character not part of the rule.
*/
static const char *getrule(const char *strp, struct rule *const rulep)
{
	if (*strp == 'J') {
		/*
		** Julian day.
		*/
		rulep->r_type = JULIAN_DAY;
		++strp;
		strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
	} else if (*strp == 'M') {
		/*
		** Month, week, day.
		*/
		rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
		++strp;
		strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
		if (strp == NULL)
			return NULL;
		if (*strp++ != '.')
			return NULL;
		strp = getnum(strp, &rulep->r_week, 1, 5);
		if (strp == NULL)
			return NULL;
		if (*strp++ != '.')
			return NULL;
		strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
	} else if (is_digit(*strp)) {
		/*
		** Day of year.
		*/
		rulep->r_type = DAY_OF_YEAR;
		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
	} else	return NULL;		/* invalid format */
	if (strp == NULL)
		return NULL;
	if (*strp == '/') {
		/*
		** Time specified.
		*/
		++strp;
		strp = getsecs(strp, &rulep->r_time);
	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
	return strp;
}

static void settzname(void)
{
	struct state * 	sp = lclptr;
	int			i;

	tzname[0] = WILDABBR;
	tzname[1] = WILDABBR;
#ifdef USG_COMPAT
	daylight = 0;
	timezone = 0;
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
	altzone = 0;
#endif /* defined ALTZONE */
#ifdef ALL_STATE
	if (sp == NULL) {
		tzname[0] = tzname[1] = gmt;
		return;
	}
#endif /* defined ALL_STATE */
	/*
	** And to get the latest zone names into tzname. . .
	*/
	for (i = 0; i < sp->typecnt; ++i) {
		const struct ttinfo * const ttisp = &sp->ttis[sp->types[i]];

		tzname[ttisp->tt_isdst] =
			&sp->chars[ttisp->tt_abbrind];
#ifdef USG_COMPAT
		if (ttisp->tt_isdst)
			daylight = 1;
		if (!ttisp->tt_isdst)
			timezone = -(ttisp->tt_gmtoff);
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
		if (ttisp->tt_isdst)
			altzone = -(ttisp->tt_gmtoff);
#endif /* defined ALTZONE */
	}
	/*
	** Finally, scrub the abbreviations.
	** First, replace bogus characters.
	*/
	for (i = 0; i < sp->charcnt; ++i) {
		if (strchr(TZ_ABBR_CHAR_SET, sp->chars[i]) == NULL) {
			sp->chars[i] = TZ_ABBR_ERR_CHAR;
		}
	}
	/*
	** Second, truncate long abbreviations.
	*/
	for (i = 0; i < sp->typecnt; ++i) {
		register const struct ttinfo * const	ttisp = &sp->ttis[i];
		register char *				cp = &sp->chars[ttisp->tt_abbrind];

		if (strlen(cp) > TZ_ABBR_MAX_LEN) {
			cp[TZ_ABBR_MAX_LEN] = 0;
		}
	}
}

static int tz_name_contains_unsafe_path(const char *name) {
	if(name[0] == ':' && name[1] == '/') return 1;
	if(name[0] == '/') return 1;
	if(strstr(name, "../")) return 1;
	return 0;
}

/*
** Given the Epoch-relative time of January 1, 00:00:00 UTC, in a year, the
** year, a rule, and the offset from UTC at the time that rule takes effect,
** calculate the Epoch-relative time that rule takes effect.
*/
static time_t transtime(const time_t janfirst, const int year, const struct rule *const rulep, const long int offset)
{
	int	leapyear;
	time_t	value;
	int	i;
	int	d, m1, yy0, yy1, yy2, dow;

	leapyear = __isleap(year);
	switch (rulep->r_type) {
	case JULIAN_DAY:
		/*
		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
		** years.
		** In non-leap years, or if the day number is 59 or less, just
		** add SECSPERDAY times the day number-1 to the time of
		** January 1, midnight, to get the day.
		*/
		value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
		if (leapyear && rulep->r_day >= 60)
			value += SECSPERDAY;
		break;

	case DAY_OF_YEAR:
		/*
		** n - day of year.
		** Just add SECSPERDAY times the day number to the time of
		** January 1, midnight, to get the day.
		*/
		value = janfirst + rulep->r_day * SECSPERDAY;
		break;

	case MONTH_NTH_DAY_OF_WEEK:
		/*
		** Mm.n.d - nth "dth day" of month m.
		*/
		value = janfirst;
		for (i = 0; i < rulep->r_mon - 1; ++i)
			value += mon_lengths[leapyear][i] * SECSPERDAY;

		/*
		** Use Zeller's Congruence to get day-of-week of first day of
		** month.
		*/
		m1 = (rulep->r_mon + 9) % 12 + 1;
		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
		yy1 = yy0 / 100;
		yy2 = yy0 % 100;
		dow = ((26 * m1 - 2) / 10 +
			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
		if (dow < 0)
			dow += DAYSPERWEEK;

		/*
		** "dow" is the day-of-week of the first day of the month. Get
		** the day-of-month (zero-origin) of the first "dow" day of the
		** month.
		*/
		d = rulep->r_day - dow;
		if (d < 0)
			d += DAYSPERWEEK;
		for (i = 1; i < rulep->r_week; ++i) {
			if (d + DAYSPERWEEK >=
				mon_lengths[leapyear][rulep->r_mon - 1])
					break;
			d += DAYSPERWEEK;
		}

		/*
		** "d" is the day-of-month (zero-origin) of the day we want.
		*/
		value += d * SECSPERDAY;
		break;
	default:
		return -1;
	}

	/*
	** "value" is the Epoch-relative time of 00:00:00 UTC on the day in
	** question. To get the Epoch-relative time of the specified local
	** time on that day, add the transition time and the current offset
	** from UTC.
	*/
	return value + rulep->r_time + offset;
}

/*
** Given a POSIX section 8-style TZ string, fill in the rule tables as
** appropriate.
*/
static int tzparse(const char *name, struct state *const sp, const int lastditch)
{
	const char *			stdname;
	const char *			dstname;
	size_t				stdlen;
	size_t				dstlen;
	long				stdoffset;
	long				dstoffset;
	time_t *		atp;
	unsigned char *	typep;
	char *			cp;
	int			load_result;

	stdname = name;
	if (lastditch) {
		stdlen = strlen(name);	/* length of standard zone name */
		name += stdlen;
		if (stdlen >= sizeof sp->chars)
			stdlen = (sizeof sp->chars) - 1;
		stdoffset = 0;
	} else {
		if (*name == '<') {
			name++;
			stdname = name;
			name = getqzname(name, '>');
			if (*name != '>')
				return (-1);
			stdlen = name - stdname;
			name++;
		} else {
			name = getzname(name);
			stdlen = name - stdname;
		}
		if (*name == '\0')
			return -1;	/* was "stdoffset = 0;" */
		else {
			name = getoffset(name, &stdoffset);
			if (name == NULL)
				return -1;
		}
	}
	load_result = tzload(TZDEFRULES, sp, 0);
	if (load_result != 0)
		sp->leapcnt = 0;		/* so, we're off a little */
	if (*name != '\0') {
		if (*name == '<') {
			dstname = ++name;
			name = getqzname(name, '>');
			if (*name != '>')
				return -1;
			dstlen = name - dstname;
			name++;
		} else {
			dstname = name;
			name = getzname(name);
			dstlen = name - dstname; /* length of DST zone name */
		}
		if (*name != '\0' && *name != ',' && *name != ';') {
			name = getoffset(name, &dstoffset);
			if (name == NULL)
				return -1;
		} else	dstoffset = stdoffset - SECSPERHOUR;
		if (*name == '\0' && load_result != 0)
			name = TZDEFRULESTRING;
		if (*name == ',' || *name == ';') {
			struct rule	start;
			struct rule	end;
			int	year;
			time_t	janfirst;
			time_t		starttime;
			time_t		endtime;

			++name;
			if ((name = getrule(name, &start)) == NULL)
				return -1;
			if (*name++ != ',')
				return -1;
			if ((name = getrule(name, &end)) == NULL)
				return -1;
			if (*name != '\0')
				return -1;
			sp->typecnt = 2;	/* standard time and DST */
			/*
			** Two transitions per year, from EPOCH_YEAR forward.
			*/
			sp->ttis[0].tt_gmtoff = -dstoffset;
			sp->ttis[0].tt_isdst = 1;
			sp->ttis[0].tt_abbrind = stdlen + 1;
			sp->ttis[1].tt_gmtoff = -stdoffset;
			sp->ttis[1].tt_isdst = 0;
			sp->ttis[1].tt_abbrind = 0;
			atp = sp->ats;
			typep = sp->types;
			janfirst = 0;
			sp->timecnt = 0;
			for (year = EPOCH_YEAR;
			    sp->timecnt + 2 <= TZ_MAX_TIMES;
			    ++year) {
			    	time_t	newfirst;

				starttime = transtime(janfirst, year, &start,
					stdoffset);
				endtime = transtime(janfirst, year, &end,
					dstoffset);
				if (starttime > endtime) {
					*atp++ = endtime;
					*typep++ = 1;	/* DST ends */
					*atp++ = starttime;
					*typep++ = 0;	/* DST begins */
				} else {
					*atp++ = starttime;
					*typep++ = 0;	/* DST begins */
					*atp++ = endtime;
					*typep++ = 1;	/* DST ends */
				}
				sp->timecnt += 2;
				newfirst = janfirst;
				newfirst += year_lengths[__isleap(year)] *
					SECSPERDAY;
				if (newfirst <= janfirst)
					break;
				janfirst = newfirst;
			}
		} else {
			long	theirstdoffset;
			long	theirdstoffset;
			long	theiroffset;
			int	isdst;
			int	i;
			int	j;

			if (*name != '\0')
				return -1;
			/*
			** Initial values of theirstdoffset and theirdstoffset.
			*/
			theirstdoffset = 0;
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				if (!sp->ttis[j].tt_isdst) {
					theirstdoffset =
						-sp->ttis[j].tt_gmtoff;
					break;
				}
			}
			theirdstoffset = 0;
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				if (sp->ttis[j].tt_isdst) {
					theirdstoffset =
						-sp->ttis[j].tt_gmtoff;
					break;
				}
			}
			/*
			** Initially we're assumed to be in standard time.
			*/
			isdst = 0;
			theiroffset = theirstdoffset;
			/*
			** Now juggle transition times and types
			** tracking offsets as you do.
			*/
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				sp->types[i] = sp->ttis[j].tt_isdst;
				if (sp->ttis[j].tt_ttisgmt) {
					/* No adjustment to transition time */
				} else {
					/*
					** If summer time is in effect, and the
					** transition time was not specified as
					** standard time, add the summer time
					** offset to the transition time;
					** otherwise, add the standard time
					** offset to the transition time.
					*/
					/*
					** Transitions from DST to DDST
					** will effectively disappear since
					** POSIX provides for only one DST
					** offset.
					*/
					if (isdst && !sp->ttis[j].tt_ttisstd) {
						sp->ats[i] += dstoffset -
							theirdstoffset;
					} else {
						sp->ats[i] += stdoffset -
							theirstdoffset;
					}
				}
				theiroffset = -sp->ttis[j].tt_gmtoff;
				if (sp->ttis[j].tt_isdst)
					theirdstoffset = theiroffset;
				else	theirstdoffset = theiroffset;
			}
			/*
			** Finally, fill in ttis.
			** ttisstd and ttisgmt need not be handled.
			*/
			sp->ttis[0].tt_gmtoff = -stdoffset;
			sp->ttis[0].tt_isdst = 0;
			sp->ttis[0].tt_abbrind = 0;
			sp->ttis[1].tt_gmtoff = -dstoffset;
			sp->ttis[1].tt_isdst = 1;
			sp->ttis[1].tt_abbrind = stdlen + 1;
			sp->typecnt = 2;
		}
	} else {
		dstlen = 0;
		sp->typecnt = 1;		/* only standard time */
		sp->timecnt = 0;
		sp->ttis[0].tt_gmtoff = -stdoffset;
		sp->ttis[0].tt_isdst = 0;
		sp->ttis[0].tt_abbrind = 0;
	}
	sp->charcnt = stdlen + 1;
	if (dstlen != 0)
		sp->charcnt += dstlen + 1;
	if ((size_t) sp->charcnt > sizeof sp->chars)
		return -1;
	cp = sp->chars;
	(void) strncpy(cp, stdname, stdlen);
	cp += stdlen;
	*cp++ = '\0';
	if (dstlen != 0) {
		(void) strncpy(cp, dstname, dstlen);
		*(cp + dstlen) = '\0';
	}
	return 0;
}

static int differ_by_repeat(const time_t t1, const time_t t0)
{
	int_fast64_t _t0 = t0;
	int_fast64_t _t1 = t1;
	if (TYPE_INTEGRAL(time_t) && TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS) {
		return 0;
	}
	return _t1 - _t0 == SECSPERREPEAT;
}

static int tzload(const char *name, struct state *const sp, const int doextend)
{
	const char *	p;
	int		i;
	int		stored;
	int		nread;
	int		res;
	union {
		struct tzhead	tzhead;
		char		buf[2 * sizeof(struct tzhead) +
					2 * sizeof *sp +
					4 * TZ_MAX_TIMES];
	} *u;

	u = NULL;
	res = -1;
	sp->goback = sp->goahead = 0;

	if (name && tz_name_contains_unsafe_path(name)) name = NULL;
	if(!name) {
		TIME_ZONE_INFORMATION tzi;
		long int status = RtlQueryTimeZoneInformation(&tzi);
		if(status >= 0) {
			char tzname[128];
			int stdname_len = wcstombs(tzname, tzi.StandardName, sizeof tzname);
			int dstname_len = stdname_len < 0 ? -1 : wcstombs(tzname + stdname_len + 1, tzi.DaylightName, sizeof tzname - stdname_len);
			if(tzi.DaylightBias) {
				sp->typecnt = 2;
				sp->ttis[0].tt_gmtoff = -(tzi.Bias * 60);
				sp->ttis[0].tt_isdst = 0;
				sp->ttis[0].tt_abbrind = 0;
				sp->ttis[1].tt_gmtoff = -((tzi.Bias + tzi.DaylightBias) * 60);
				sp->ttis[1].tt_isdst = 1;
				sp->ttis[1].tt_abbrind = stdname_len < 0 ? 0 : stdname_len + 1;
				sp->timecnt = 0;
			} else {
				sp->typecnt = 1;
				sp->ttis[0].tt_gmtoff = -(tzi.Bias * 60);
				sp->ttis[0].tt_isdst = 0;
				sp->ttis[0].tt_abbrind = 0;
				sp->timecnt = 0;
			}
			if(stdname_len > 0) {
				size_t len = stdname_len + 1;
				if(dstname_len > 0) len += dstname_len + 1;
				if(len > sizeof sp->chars) {
					len = sizeof sp->chars - 1;
					sp->chars[len] = 0;
				}
				memcpy(sp->chars, tzname, len);
				sp->charcnt = len;
			}
			return 0;
		}
	}

	int	doaccess;
	struct stat	stab;
	/*
	** Section 4.9.1 of the C standard says that
	** "FILENAME_MAX expands to an integral constant expression
	** that is the size needed for an array of char large enough
	** to hold the longest file name string that the implementation
	** guarantees can be opened."
	*/
	char *fullname = malloc(FILENAME_MAX + 1);
	if (fullname == NULL) goto out;

	if (name[0] == ':') ++name;
	doaccess = name[0] == '/';
	if (!doaccess) {
		if ((p = TZDIR) == NULL) {
			free(fullname);
			return -1;
		}
		if (strlen(p) + 1 + strlen(name) >= FILENAME_MAX) {
			free(fullname);
			return -1;
		}
		(void) strcpy(fullname, p);
		(void) strcat(fullname, "/");
		(void) strcat(fullname, name);
		/*
		** Set doaccess if '.' (as in "../") shows up in name.
		*/
		if (strchr(name, '.')) doaccess = 1;
		name = fullname;
	}
	if (doaccess && access(name, R_OK) != 0) {
		free(fullname);
	     	return -1;
	}
	int fd = open(name, O_RDONLY);
	if (fd == -1) {
		free(fullname);
		return -1;
	}
	if (fstat(fd, &stab) < 0 || !S_ISREG(stab.st_mode)) {
		free(fullname);
		close(fd);
		return -1;
	}
	free(fullname);
	u = malloc(sizeof(*u));
	if (!u) goto out;
	nread = read(fd, u->buf, sizeof u->buf);
	if (close(fd) < 0 || nread <= 0) goto out;
	for (stored = 4; stored <= 8; stored *= 2) {
		int		ttisstdcnt;
		int		ttisgmtcnt;

		ttisstdcnt = (int) detzcode(u->tzhead.tzh_ttisstdcnt);
		ttisgmtcnt = (int) detzcode(u->tzhead.tzh_ttisgmtcnt);
		sp->leapcnt = (int) detzcode(u->tzhead.tzh_leapcnt);
		sp->timecnt = (int) detzcode(u->tzhead.tzh_timecnt);
		sp->typecnt = (int) detzcode(u->tzhead.tzh_typecnt);
		sp->charcnt = (int) detzcode(u->tzhead.tzh_charcnt);
		p = u->tzhead.tzh_charcnt + sizeof u->tzhead.tzh_charcnt;
		if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
			sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
			sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
			sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
			(ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
			(ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
				goto out;
		if (nread - (p - u->buf) <
			sp->timecnt * stored +		/* ats */
			sp->timecnt +			/* types */
			sp->typecnt * 6 +		/* ttinfos */
			sp->charcnt +			/* chars */
			sp->leapcnt * (stored + 4) +	/* lsinfos */
			ttisstdcnt +			/* ttisstds */
			ttisgmtcnt)			/* ttisgmts */
				goto out;
		for (i = 0; i < sp->timecnt; ++i) {
			sp->ats[i] = (stored == 4) ?
				detzcode(p) : detzcode64(p);
			p += stored;
		}
		for (i = 0; i < sp->timecnt; ++i) {
			sp->types[i] = (unsigned char) *p++;
			if (sp->types[i] >= sp->typecnt)
				goto out;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			ttisp->tt_gmtoff = detzcode(p);
			p += 4;
			ttisp->tt_isdst = (unsigned char) *p++;
			if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
				goto out;
			ttisp->tt_abbrind = (unsigned char) *p++;
			if (ttisp->tt_abbrind < 0 ||
				ttisp->tt_abbrind > sp->charcnt)
					goto out;
		}
		for (i = 0; i < sp->charcnt; ++i)
			sp->chars[i] = *p++;
		sp->chars[i] = '\0';	/* ensure '\0' at end */
		for (i = 0; i < sp->leapcnt; ++i) {
			struct lsinfo *	lsisp;

			lsisp = &sp->lsis[i];
			lsisp->ls_trans = (stored == 4) ?
				detzcode(p) : detzcode64(p);
			p += stored;
			lsisp->ls_corr = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			struct ttinfo *ttisp = sp->ttis + i;
			if (ttisstdcnt == 0) {
				ttisp->tt_ttisstd = 0;
			} else {
				ttisp->tt_ttisstd = *p++;
				if (!ttisp->tt_ttisstd && ttisp->tt_ttisstd) {
					goto out;
				}
			}
		}
		for (i = 0; i < sp->typecnt; ++i) {
			struct ttinfo *ttisp = sp->ttis + i;;
			if (ttisgmtcnt == 0) {
				ttisp->tt_ttisgmt = 0;
			} else {
				ttisp->tt_ttisgmt = *p++;
				if (!ttisp->tt_ttisgmt && ttisp->tt_ttisgmt) {
					goto out;
				}
			}
		}
		/*
		** Out-of-sort ats should mean we're running on a
		** signed time_t system but using a data file with
		** unsigned values (or vice versa).
		*/
		for (i = 0; i < sp->timecnt - 2; ++i)
			if (sp->ats[i] > sp->ats[i + 1]) {
				++i;
				if (TYPE_SIGNED(time_t)) {
					/*
					** Ignore the end (easy).
					*/
					sp->timecnt = i;
				} else {
					/*
					** Ignore the beginning (harder).
					*/
					register int	j;

					for (j = 0; j + i < sp->timecnt; ++j) {
						sp->ats[j] = sp->ats[j + i];
						sp->types[j] = sp->types[j + i];
					}
					sp->timecnt = j;
				}
				break;
			}
		/*
		** If this is an old file, we're done.
		*/
		if (u->tzhead.tzh_version[0] == '\0')
			break;
		nread -= p - u->buf;
		for (i = 0; i < nread; ++i)
			u->buf[i] = p[i];
		/*
		** If this is a narrow integer time_t system, we're done.
		*/
		if (stored >= (int) sizeof(time_t) && TYPE_INTEGRAL(time_t))
			break;
	}
	if (doextend && nread > 2 &&
		u->buf[0] == '\n' && u->buf[nread - 1] == '\n' &&
		sp->typecnt + 2 <= TZ_MAX_TYPES) {
			struct state	*ts;
			register int	result;

			ts = malloc(sizeof(*ts));
			if (ts == NULL)
				goto out;
			u->buf[nread - 1] = '\0';
			result = tzparse(&u->buf[1], ts, 0);
			if (result == 0 && ts->typecnt == 2 &&
				sp->charcnt + ts->charcnt <= TZ_MAX_CHARS) {
					for (i = 0; i < 2; ++i)
						ts->ttis[i].tt_abbrind +=
							sp->charcnt;
					for (i = 0; i < ts->charcnt; ++i)
						sp->chars[sp->charcnt++] =
							ts->chars[i];
					i = 0;
					while (i < ts->timecnt &&
						ts->ats[i] <=
						sp->ats[sp->timecnt - 1])
							++i;
					while (i < ts->timecnt &&
					    sp->timecnt < TZ_MAX_TIMES) {
						sp->ats[sp->timecnt] =
							ts->ats[i];
						sp->types[sp->timecnt] =
							sp->typecnt +
							ts->types[i];
						++sp->timecnt;
						++i;
					}
					sp->ttis[sp->typecnt++] = ts->ttis[0];
					sp->ttis[sp->typecnt++] = ts->ttis[1];
			}
			free(ts);
	}
	if (sp->timecnt > 1) {
		for (i = 1; i < sp->timecnt; ++i) {
			if (typesequiv(sp, sp->types[i], sp->types[0]) && differ_by_repeat(sp->ats[i], sp->ats[0])) {
				sp->goback = 1;
				break;
			}
		}
		for (i = sp->timecnt - 2; i >= 0; --i) {
			if (typesequiv(sp, sp->types[sp->timecnt - 1],
				sp->types[i]) &&
				differ_by_repeat(sp->ats[sp->timecnt - 1],
				sp->ats[i])) {
					sp->goahead = 1;
					break;
			}
		}
	}
	res = 0;
out:
	free(u);
	return (res);
}

static void gmtload(struct state *const sp)
{
	if (tzload(GMT, sp, 1) < 0) tzparse(GMT, sp, 1);
}

void tzsetwall() {
	_RWLOCK_RDLOCK(&lcl_rwlock);
	if (lcl_is_set < 0) {
		_RWLOCK_UNLOCK(&lcl_rwlock);
		return;
	}
	_RWLOCK_UNLOCK(&lcl_rwlock);

	_RWLOCK_WRLOCK(&lcl_rwlock);
	lcl_is_set = -1;

#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = calloc(1, sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();	/* all we can do */
			_RWLOCK_UNLOCK(&lcl_rwlock);
			return;
		}
	}
#endif /* defined ALL_STATE */
	if (tzload((char *) NULL, lclptr, 1) < 0) gmtload(lclptr);
	settzname();
	_RWLOCK_UNLOCK(&lcl_rwlock);
}

void tzset() {
	const char *name = getenv("TZ");
	if(!name) return tzsetwall();

	_RWLOCK_RDLOCK(&lcl_rwlock);
	if (lcl_is_set > 0 && strcmp(lcl_TZname, name) == 0) {
		_RWLOCK_UNLOCK(&lcl_rwlock);
		return;
	}
	_RWLOCK_UNLOCK(&lcl_rwlock);

	_RWLOCK_WRLOCK(&lcl_rwlock);
	lcl_is_set = strlen(name) < sizeof lcl_TZname;
	if (lcl_is_set) strcpy(lcl_TZname, name);

#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = (struct state *) calloc(1, sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();	/* all we can do */
			_RWLOCK_UNLOCK(&lcl_rwlock);
			return;
		}
	}
#endif /* defined ALL_STATE */
	if (*name == '\0') {
		/*
		** User wants it fast rather than right.
		*/
		lclptr->leapcnt = 0;		/* so, we're off a little */
		lclptr->timecnt = 0;
		lclptr->typecnt = 0;
		lclptr->ttis[0].tt_isdst = 0;
		lclptr->ttis[0].tt_gmtoff = 0;
		lclptr->ttis[0].tt_abbrind = 0;
		strcpy(lclptr->chars, GMT);
	} else if (tzload(name, lclptr, 1) != 0) {
		if (name[0] == ':' || tzparse(name, lclptr, 0) < 0) gmtload(lclptr);
	}
	settzname();
	_RWLOCK_UNLOCK(&lcl_rwlock);
}

/*
** Simplified normalize logic courtesy Paul Eggert.
*/
static int increment_overflow(int *number, int delta)
{
	int number0 = *number;
	*number += delta;
	return (*number < number0) != (delta < 0);
}

static int normalize_overflow(int *const tensptr, int *const unitsptr, const int base)
{
	int tensdelta = (*unitsptr >= 0) ?
		(*unitsptr / base) :
		(-1 - (-1 - *unitsptr) / base);
	*unitsptr -= tensdelta * base;
	return increment_overflow(tensptr, tensdelta);
}

static int tmcomp(const struct tm *a, const struct tm *b)
{
	int diff = a->tm_year - b->tm_year;
	if(diff) return diff;
	diff = a->tm_mon - b->tm_mon;
	if(diff) return diff;
	diff = a->tm_mday - b->tm_mday;
	if(diff) return diff;
	diff = a->tm_hour - b->tm_hour;
	if(diff) return diff;
	diff = a->tm_min - b->tm_min;
	if(diff) return diff;
	return a->tm_sec - b->tm_sec;
}

static time_t time2sub(struct tm *const tmp, struct tm *(*const funcp)(const time_t *, long, struct tm *), const long int offset, int *const okayp, const int do_norm_secs)
{
	const struct state *	sp;
	int			dir;
	int			i, j;
	int			saved_seconds;
	int			li;
	time_t			lo;
	time_t			hi;
	int			y;
	time_t			newt;
	time_t			t;
	struct tm		yourtm, mytm;

	*okayp = 0;
	yourtm = *tmp;
	if (do_norm_secs) {
		if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
			SECSPERMIN))
				return WRONG;
	}
	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
		return WRONG;
	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
		return WRONG;
	y = yourtm.tm_year;
	if (normalize_overflow(&y, &yourtm.tm_mon, MONSPERYEAR)) return WRONG;
	/*
	** Turn y into an actual year number for now.
	** It is converted back to an offset from TM_YEAR_BASE later.
	*/
	if (increment_overflow(&y, TM_YEAR_BASE)) return WRONG;
	while (yourtm.tm_mday <= 0) {
		if (increment_overflow(&y, -1)) return WRONG;
		li = y + (1 < yourtm.tm_mon);
		yourtm.tm_mday += year_lengths[__isleap(li)];
	}
	while (yourtm.tm_mday > DAYSPERLYEAR) {
		li = y + (1 < yourtm.tm_mon);
		yourtm.tm_mday -= year_lengths[__isleap(li)];
		if (increment_overflow(&y, 1)) return WRONG;
	}
	for ( ; ; ) {
		i = mon_lengths[__isleap(y)][yourtm.tm_mon];
		if (yourtm.tm_mday <= i)
			break;
		yourtm.tm_mday -= i;
		if (++yourtm.tm_mon >= MONSPERYEAR) {
			yourtm.tm_mon = 0;
			if (increment_overflow(&y, 1)) return WRONG;
		}
	}
	if (increment_overflow(&y, -TM_YEAR_BASE)) return WRONG;
	yourtm.tm_year = y;
	if (yourtm.tm_year != y)
		return WRONG;
	/* Don't go below 1900 for POLA */
	if (yourtm.tm_year < 0)
		return WRONG;
	if (yourtm.tm_sec >= 0 && yourtm.tm_sec < SECSPERMIN)
		saved_seconds = 0;
	else if (y + TM_YEAR_BASE < EPOCH_YEAR) {
		/*
		** We can't set tm_sec to 0, because that might push the
		** time below the minimum representable time.
		** Set tm_sec to 59 instead.
		** This assumes that the minimum representable time is
		** not in the same minute that a leap second was deleted from,
		** which is a safer assumption than using 58 would be.
		*/
		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
			return WRONG;
		saved_seconds = yourtm.tm_sec;
		yourtm.tm_sec = SECSPERMIN - 1;
	} else {
		saved_seconds = yourtm.tm_sec;
		yourtm.tm_sec = 0;
	}
	/*
	** Do a binary search (this works whatever time_t's type is).
	*/
	if (!TYPE_SIGNED(time_t)) {
		lo = 0;
		hi = lo - 1;
	} else if (!TYPE_INTEGRAL(time_t)) {
		if (sizeof(time_t) > sizeof(float))
			hi = (time_t) DBL_MAX;
		else	hi = (time_t) FLT_MAX;
		lo = -hi;
	} else {
		lo = 1;
		for (i = 0; i < (int) TYPE_BIT(time_t) - 1; ++i)
			lo *= 2;
		hi = -(lo + 1);
	}
	for ( ; ; ) {
		t = lo / 2 + hi / 2;
		if (t < lo)
			t = lo;
		else if (t > hi)
			t = hi;
		if (!funcp(&t, offset, &mytm)) {
			/*
			** Assume that t is too extreme to be represented in
			** a struct tm; arrange things so that it is less
			** extreme on the next pass.
			*/
			dir = (t > 0) ? 1 : -1;
		} else	dir = tmcomp(&mytm, &yourtm);
		if (dir != 0) {
			if (t == lo) {
				++t;
				if (t <= lo)
					return WRONG;
				++lo;
			} else if (t == hi) {
				--t;
				if (t >= hi)
					return WRONG;
				--hi;
			}
			if (lo > hi)
				return WRONG;
			if (dir > 0)
				hi = t;
			else	lo = t;
			continue;
		}
		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
			break;
		/*
		** Right time, wrong type.
		** Hunt for right time, right type.
		** It's okay to guess wrong since the guess
		** gets checked.
		*/
		sp = (const struct state *)
			((funcp == localsub) ? lclptr : gmtptr);
#ifdef ALL_STATE
		if (sp == NULL)
			return WRONG;
#endif /* defined ALL_STATE */
		for (i = sp->typecnt - 1; i >= 0; --i) {
			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
				continue;
			for (j = sp->typecnt - 1; j >= 0; --j) {
				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
					continue;
				newt = t + sp->ttis[j].tt_gmtoff -
					sp->ttis[i].tt_gmtoff;
				if (!funcp(&newt, offset, &mytm)) continue;
				if (tmcomp(&mytm, &yourtm) != 0)
					continue;
				if (mytm.tm_isdst != yourtm.tm_isdst)
					continue;
				/*
				** We have a match.
				*/
				t = newt;
				goto label;
			}
		}
		return WRONG;
	}
label:
	newt = t + saved_seconds;
	if ((newt < t) != (saved_seconds < 0))
		return WRONG;
	t = newt;
	if (funcp(&t, offset, tmp)) *okayp = 1;
	return t;
}

static time_t time2(struct tm *const tmp, struct tm *(*const funcp)(const time_t *, long, struct tm *), const long offset, int *const okayp)
{
	/*
	** First try without normalization of seconds
	** (in case tm_sec contains a value associated with a leap second).
	** If that fails, try with normalization of seconds.
	*/
	time_t t = time2sub(tmp, funcp, offset, okayp, 0);
	if(*okayp) return t;
	return time2sub(tmp, funcp, offset, okayp, 1);
}

/*
** Return the number of leap years through the end of the given year
** where, to make the math easy, the answer for year zero is defined as zero.
*/
static int leaps_thru_end_of(const int y)
{
	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
		-(leaps_thru_end_of(-(y + 1)) + 1);
}

static struct tm *timesub(const time_t *const timep, const long int offset, const struct state *const sp, struct tm *const tmp)
{
	const struct lsinfo *	lp;
	time_t			tdays;
	int			idays;	/* unsigned would be so 2003 */
	long			rem;
	int			y;
	const int *		ip;
	long			corr;
	int			hit;
	int			i;

	corr = 0;
	hit = 0;
#ifdef ALL_STATE
	i = (sp == NULL) ? 0 : sp->leapcnt;
#else
	i = sp->leapcnt;
#endif
	while (--i >= 0) {
		lp = &sp->lsis[i];
		if (*timep >= lp->ls_trans) {
			if (*timep == lp->ls_trans) {
				hit = ((i == 0 && lp->ls_corr > 0) ||
					lp->ls_corr > sp->lsis[i - 1].ls_corr);
				if (hit)
					while (i > 0 &&
						sp->lsis[i].ls_trans ==
						sp->lsis[i - 1].ls_trans + 1 &&
						sp->lsis[i].ls_corr ==
						sp->lsis[i - 1].ls_corr + 1) {
							++hit;
							--i;
					}
			}
			corr = lp->ls_corr;
			break;
		}
	}
	y = EPOCH_YEAR;
	tdays = *timep / SECSPERDAY;
	rem = *timep - tdays * SECSPERDAY;
	while (tdays < 0 || tdays >= year_lengths[__isleap(y)]) {
		int		newy;
		register time_t	tdelta;
		register int	idelta;
		register int	leapdays;

		tdelta = tdays / DAYSPERLYEAR;
		idelta = tdelta;
		if (tdelta - idelta >= 1 || idelta - tdelta >= 1)
			return NULL;
		if (idelta == 0)
			idelta = (tdays < 0) ? -1 : 1;
		newy = y;
		if (increment_overflow(&newy, idelta))
			return NULL;
		leapdays = leaps_thru_end_of(newy - 1) -
			leaps_thru_end_of(y - 1);
		tdays -= ((time_t) newy - y) * DAYSPERNYEAR;
		tdays -= leapdays;
		y = newy;
	}
	{
		register long	seconds;

		seconds = tdays * SECSPERDAY + 0.5;
		tdays = seconds / SECSPERDAY;
		rem += seconds - tdays * SECSPERDAY;
	}
	/*
	** Given the range, we can now fearlessly cast...
	*/
	idays = tdays;
	rem += offset - corr;
	while (rem < 0) {
		rem += SECSPERDAY;
		--idays;
	}
	while (rem >= SECSPERDAY) {
		rem -= SECSPERDAY;
		++idays;
	}
	while (idays < 0) {
		if (increment_overflow(&y, -1))
			return NULL;
		idays += year_lengths[__isleap(y)];
	}
	while (idays >= year_lengths[__isleap(y)]) {
		idays -= year_lengths[__isleap(y)];
		if (increment_overflow(&y, 1))
			return NULL;
	}
	tmp->tm_year = y;
	if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE))
		return NULL;
	tmp->tm_yday = idays;
	/*
	** The "extra" mods below avoid overflow problems.
	*/
	tmp->tm_wday = EPOCH_WDAY +
		((y - EPOCH_YEAR) % DAYSPERWEEK) *
		(DAYSPERNYEAR % DAYSPERWEEK) +
		leaps_thru_end_of(y - 1) -
		leaps_thru_end_of(EPOCH_YEAR - 1) +
		idays;
	tmp->tm_wday %= DAYSPERWEEK;
	if (tmp->tm_wday < 0)
		tmp->tm_wday += DAYSPERWEEK;
	tmp->tm_hour = (int) (rem / SECSPERHOUR);
	rem %= SECSPERHOUR;
	tmp->tm_min = (int) (rem / SECSPERMIN);
	/*
	** A positive leap second requires a special
	** representation. This uses "... ??:59:60" et seq.
	*/
	tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
	ip = mon_lengths[__isleap(y)];
	for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
		idays -= ip[tmp->tm_mon];
	tmp->tm_mday = (int) (idays + 1);
	tmp->tm_isdst = 0;
	return tmp;
}

/*
** The easy way to behave "as if no library function calls" localtime
** is to not call it--so we drop its guts into "localsub", which can be
** freely called. (And no, the PANS doesn't require the above behavior--
** but it *is* desirable.)
**
** The unused offset argument is for the benefit of mktime variants.
*/
/*ARGSUSED*/
static struct tm *localsub(const time_t *const timep, const long offset, struct tm *const tmp)
{
	struct state *		sp;
	const struct ttinfo *	ttisp;
	int			i;
	struct tm *		result;
	const time_t		t = *timep;

	sp = lclptr;
#ifdef ALL_STATE
	if (sp == NULL)
		return gmtsub(timep, offset, tmp);
#endif /* defined ALL_STATE */
	if ((sp->goback && t < sp->ats[0]) ||
		(sp->goahead && t > sp->ats[sp->timecnt - 1])) {
			time_t			newt = t;
			register time_t		seconds;
			register time_t		tcycles;
			register int_fast64_t	icycles;

			if (t < sp->ats[0])
				seconds = sp->ats[0] - t;
			else	seconds = t - sp->ats[sp->timecnt - 1];
			--seconds;
			tcycles = seconds / YEARSPERREPEAT / AVGSECSPERYEAR;
			++tcycles;
			icycles = tcycles;
			if (tcycles - icycles >= 1 || icycles - tcycles >= 1)
				return NULL;
			seconds = icycles;
			seconds *= YEARSPERREPEAT;
			seconds *= AVGSECSPERYEAR;
			if (t < sp->ats[0])
				newt += seconds;
			else	newt -= seconds;
			if (newt < sp->ats[0] ||
				newt > sp->ats[sp->timecnt - 1])
					return NULL;	/* "cannot happen" */
			result = localsub(&newt, offset, tmp);
			if (result == tmp) {
				register time_t	newy;

				newy = tmp->tm_year;
				if (t < sp->ats[0])
					newy -= icycles * YEARSPERREPEAT;
				else	newy += icycles * YEARSPERREPEAT;
				tmp->tm_year = newy;
				if (tmp->tm_year != newy)
					return NULL;
			}
			return result;
	}
	if (sp->timecnt == 0 || t < sp->ats[0]) {
		i = 0;
		while (sp->ttis[i].tt_isdst)
			if (++i >= sp->typecnt) {
				i = 0;
				break;
			}
	} else {
		register int	lo = 1;
		register int	hi = sp->timecnt;

		while (lo < hi) {
			register int	mid = (lo + hi) >> 1;

			if (t < sp->ats[mid])
				hi = mid;
			else	lo = mid + 1;
		}
		i = (int) sp->types[lo - 1];
	}
	ttisp = &sp->ttis[i];
	/*
	** To get (wrong) behavior that's compatible with System V Release 2.0
	** you'd replace the statement below with
	**	t += ttisp->tt_gmtoff;
	**	timesub(&t, 0L, sp, tmp);
	*/
	result = timesub(&t, ttisp->tt_gmtoff, sp, tmp);
	tmp->tm_isdst = ttisp->tt_isdst;
	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
	return result;
}

/*
** gmtsub is to gmtime as localsub is to localtime.
*/
static struct tm *gmtsub(const time_t *const timep, const long int offset, struct tm *const tmp)
{
	return timesub(timep, offset, gmtptr, tmp);
}

static time_t time1(struct tm *const tmp, struct tm *(*const funcp)(const time_t *, long, struct tm *), const long int offset)
{
	time_t			t;
	const struct state *	sp;
	int			samei, otheri;
	int			sameind, otherind;
	int			i;
	int			nseen;
	int			seen[TZ_MAX_TYPES];
	int			types[TZ_MAX_TYPES];
	int			okay;

	if (tmp == NULL) {
		errno = EINVAL;
		return WRONG;
	}

	if (tmp->tm_isdst > 1)
		tmp->tm_isdst = 1;
	t = time2(tmp, funcp, offset, &okay);
#ifdef PCTS
	/*
	** PCTS code courtesy Grant Sullivan.
	*/
	if (okay)
		return t;
	if (tmp->tm_isdst < 0)
		tmp->tm_isdst = 0;	/* reset to std and try again */
#else
	if (okay || tmp->tm_isdst < 0)
		return t;
#endif /* !defined PCTS */
	/*
	** We're supposed to assume that somebody took a time of one type
	** and did some math on it that yielded a "struct tm" that's bad.
	** We try to divine the type they started from and adjust to the
	** type they need.
	*/
	sp = (const struct state *) ((funcp == localsub) ? lclptr : gmtptr);
#ifdef ALL_STATE
	if (sp == NULL)
		return WRONG;
#endif /* defined ALL_STATE */
	for (i = 0; i < sp->typecnt; ++i) seen[i] = 0;
	nseen = 0;
	for (i = sp->timecnt - 1; i >= 0; --i) {
		if (!seen[sp->types[i]]) {
			seen[sp->types[i]] = 1;
			types[nseen++] = sp->types[i];
		}
	}
	for (sameind = 0; sameind < nseen; ++sameind) {
		samei = types[sameind];
		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
			continue;
		for (otherind = 0; otherind < nseen; ++otherind) {
			otheri = types[otherind];
			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
				continue;
			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
			t = time2(tmp, funcp, offset, &okay);
			if (okay)
				return t;
			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
		}
	}
	return WRONG;
}

struct tm *localtime(const time_t *t) {
	static struct tm buffer;
	tzset();
	_RWLOCK_RDLOCK(&lcl_rwlock);
	struct tm *tm = localsub(t, 0, &buffer);
	_RWLOCK_UNLOCK(&lcl_rwlock);
	return tm;
}

struct tm *localtime_r(const time_t *t, struct tm *tm) {
	tzset();
	_RWLOCK_RDLOCK(&lcl_rwlock);
	tm = localsub(t, 0, tm);
	_RWLOCK_UNLOCK(&lcl_rwlock);
	return tm;
}

struct tm *gmtime(const time_t *t) {
	static struct tm buffer;
	return gmtsub(t, 0, &buffer);
}

struct tm *gmtime_r(const time_t *t, struct tm *tm) {
	return gmtsub(t, 0, tm);
}

time_t mktime(struct tm *const tmp)
{
	tzset();
	_RWLOCK_RDLOCK(&lcl_rwlock);
	time_t t = time1(tmp, localsub, 0L);
	_RWLOCK_UNLOCK(&lcl_rwlock);
	return t;
}

time_t timelocal(struct tm *const tmp)
{
	if (tmp != NULL)
		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
	return mktime(tmp);
}

time_t timegm(struct tm *const tmp)
{
	if (tmp != NULL)
		tmp->tm_isdst = 0;
	return time1(tmp, gmtsub, 0L);
}