/*
 * Copyright (c) 1987, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Arthur David Olson of the National Cancer Institute.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * Neither the name of the University nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ctime.c	5.23 (Berkeley) 6/22/90";

#endif /* LIBC_SCCS and not lint */

/*
** Leap second handling from Bradley White (bww@k.gp.cs.cmu.edu).
** POSIX-style TZ environment variable handling from Guy Harris
** (guy@auspex.com).
*/

/*LINTLIBRARY*/

#include <sys/param.h>
#include <fcntl.h>
#include <time.h>
#include <tzfile.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>

#ifdef __STDC__
#include <stdlib.h>

#define P(s)		s
#define alloc_size_t	size_t
#define qsort_size_t	size_t
#define fread_size_t	size_t
#define fwrite_size_t	size_t

#else /* !defined __STDC__ */

#define P(s)		()
#define const
#define volatile

typedef char *genericptr_t;
typedef unsigned alloc_size_t;
typedef int qsort_size_t;
typedef int fread_size_t;
typedef int fwrite_size_t;

extern char *calloc();
extern char *malloc();
extern char *realloc();
extern char *getenv();

#endif /* !defined __STDC__ */

extern time_t time();

#define FILENAME_MAX	MAXPATHLEN
#define ACCESS_MODE	O_RDONLY
#define OPEN_MODE	O_RDONLY

#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 */

#ifndef TRUE
#define TRUE		1
#define FALSE		0
#endif /* !defined TRUE */

static const char GMT[] = "GMT";

struct ttinfo {					/* time type information */
	long tt_gmtoff;				/* GMT 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 */
};

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

struct state {
	int leapcnt;
	int timecnt;
	int typecnt;
	int charcnt;
	time_t ats[TZ_MAX_TIMES];
	unsigned char types[TZ_MAX_TIMES];
	struct ttinfo ttis[TZ_MAX_TYPES];
	char chars[(TZ_MAX_CHARS + 1 > sizeof GMT) ?
			   TZ_MAX_CHARS + 1 : sizeof GMT];
	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 */

/*
** Prototypes for static functions.
*/

static long detzcode P((const char *codep));
static const char *getzname P((const char *strp));
static const char *getnum P((const char *strp, int *nump, int min,
							 int max));
static const char *getsecs P((const char *strp, long *secsp));
static const char *getoffset P((const char *strp, long *offsetp));
static const char *getrule P((const char *strp, struct rule * rulep));
static void gmtload P((struct state * sp));
static void gmtsub P((const time_t * timep, long offset,
					  struct tm * tmp));
static void localsub P((const time_t * timep, long offset,
						struct tm * tmp));
static void normalize P((int *tensptr, int *unitsptr, int base));
static void settzname P((void));
static time_t time1 P((struct tm * tmp, void (*funcp) (),
					   long offset));
static time_t time2 P((struct tm * tmp, void (*funcp) (),
					   long offset, int *okayp));
static void timesub P((const time_t * timep, long offset,
					   const struct state * sp, struct tm * tmp));
static int tmcomp P((const struct tm * atmp,
					 const struct tm * btmp));
static time_t transtime P((time_t janfirst, int year,
						   const struct rule * rulep, long offset));
static int tzload P((const char *name, struct state * sp));
static int tzparse P((const char *name, struct state * sp,
					  int lastditch));

#ifdef ALL_STATE
static struct state *lclptr;
static struct state *gmtptr;

#endif /* defined ALL_STATE */

#ifndef ALL_STATE
static struct state lclmem;
static struct state gmtmem;

#define lclptr		(&lclmem)
#define gmtptr		(&gmtmem)
#endif /* State Farm */

static int lcl_is_set;
static int gmt_is_set;

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

#ifdef USG_COMPAT
time_t timezone = 0;
int daylight = 0;

#endif /* defined USG_COMPAT */

#ifdef ALTZONE
time_t altzone = 0;

#endif /* defined ALTZONE */

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

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

static void
settzname()
{
	register const struct state *const sp = lclptr;
	register 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 */
	for (i = 0; i < sp->typecnt; ++i) {
		register const struct ttinfo *const ttisp = &sp->ttis[i];

		tzname[ttisp->tt_isdst] =
			(char *) &sp->chars[ttisp->tt_abbrind];
#ifdef USG_COMPAT
		if (ttisp->tt_isdst)
			daylight = 1;
		if (i == 0 || !ttisp->tt_isdst)
			timezone = -(ttisp->tt_gmtoff);
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
		if (i == 0 || ttisp->tt_isdst)
			altzone = -(ttisp->tt_gmtoff);
#endif /* defined ALTZONE */
	}
	/* * And to get the latest zone names into tzname. . . */
	for (i = 0; i < sp->timecnt; ++i) {
		register const struct ttinfo *const ttisp =
		&sp->ttis[sp->types[i]];

		tzname[ttisp->tt_isdst] =
			(char *) &sp->chars[ttisp->tt_abbrind];
	}
}

static int
tzload(name, sp)
  register const char *name;
  register struct state *const sp;
{
	register const char *p;
	register int i;
	register int fid;

	if (name == NULL && (name = TZDEFAULT) == NULL)
		return -1;
	{
		char fullname[FILENAME_MAX + 1];

		if (name[0] == ':')
			++name;
		if (name[0] != '/') {
			if ((p = TZDIR) == NULL)
				return -1;
			if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
				return -1;
			(void) strcpy(fullname, p);
			(void) strcat(fullname, "/");
			(void) strcat(fullname, name);
			name = fullname;
		}
		if ((fid = open(name, OPEN_MODE)) == -1)
			return -1;
	}
	{
		register const struct tzhead *tzhp;
		char buf[sizeof *sp + sizeof *tzhp];
		int ttisstdcnt;

		i = read(fid, buf, sizeof buf);
		if (close(fid) != 0 || i < sizeof *tzhp)
			return -1;
		tzhp = (struct tzhead *) buf;
		ttisstdcnt = (int) detzcode(tzhp->tzh_ttisstdcnt);
		sp->leapcnt = (int) detzcode(tzhp->tzh_leapcnt);
		sp->timecnt = (int) detzcode(tzhp->tzh_timecnt);
		sp->typecnt = (int) detzcode(tzhp->tzh_typecnt);
		sp->charcnt = (int) detzcode(tzhp->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))
			return -1;
		if (i < sizeof *tzhp +
			sp->timecnt * (4 + sizeof(char)) +
			sp->typecnt * (4 + 2 * sizeof(char)) +
			sp->charcnt * sizeof(char) +
			sp->leapcnt * 2 * 4 +
			ttisstdcnt * sizeof(char))
			  return -1;

		p = buf + sizeof *tzhp;
		for (i = 0; i < sp->timecnt; ++i) {
			sp->ats[i] = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->timecnt; ++i) {
			sp->types[i] = (unsigned char) *p++;
			if (sp->types[i] >= sp->typecnt)
				return -1;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			register 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)
				return -1;
			ttisp->tt_abbrind = (unsigned char) *p++;
			if (ttisp->tt_abbrind < 0 ||
				ttisp->tt_abbrind > sp->charcnt)
				return -1;
		}
		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) {
			register struct lsinfo *lsisp;

			lsisp = &sp->lsis[i];
			lsisp->ls_trans = detzcode(p);
			p += 4;
			lsisp->ls_corr = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *ttisp;

			ttisp = &sp->ttis[i];
			if (ttisstdcnt == 0)
				ttisp->tt_ttisstd = FALSE;
			else {
				ttisp->tt_ttisstd = *p++;
				if (ttisp->tt_ttisstd != TRUE &&
					ttisp->tt_ttisstd != FALSE)
					return -1;
			}
		}
	}
	return 0;
}

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
};

/*
** 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(strp)
  register const char *strp;
{
	register char c;

	while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' &&
		   c != '+')
		++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(strp, nump, min, max)
  register const char *strp;
  int *const nump;
  const int min;
  const int max;
{
	register char c;
	register int num;

	if (strp == NULL || !isdigit(*strp))
		return NULL;
	num = 0;
	while ((c = *strp) != '\0' && isdigit(c)) {
		num = num * 10 + (c - '0');
		if (num > max)
			return NULL;		/* illegal value */
		++strp;
	}
	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(strp, secsp)
  register const char *strp;
  long *const secsp;
{
	int num;

	strp = getnum(strp, &num, 0, HOURSPERDAY);
	if (strp == NULL)
		return NULL;
	*secsp = num * SECSPERHOUR;
	if (*strp == ':') {
		++strp;
		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
		if (strp == NULL)
			return NULL;
		*secsp += num * SECSPERMIN;
		if (*strp == ':') {
			++strp;
			strp = getnum(strp, &num, 0, SECSPERMIN - 1);
			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(strp, offsetp)
  register const char *strp;
  long *const offsetp;
{
	register int neg;

	if (*strp == '-') {
		neg = 1;
		++strp;
	} else if (isdigit(*strp) || *strp++ == '+')
		neg = 0;
	else
		return NULL;			/* illegal offset */
	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(strp, rulep)
  const char *strp;
  register 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 (isdigit(*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;
}

/*
** Given the Epoch-relative time of January 1, 00:00:00 GMT, in a year, the
** year, a rule, and the offset from GMT at the time that rule takes effect,
** calculate the Epoch-relative time that rule takes effect.
*/

static time_t
transtime(janfirst, year, rulep, offset)
  const time_t janfirst;
  const int year;
  register const struct rule *const rulep;
  const long offset;
{
	register int leapyear;
	register time_t value;
	register 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;
	}

	/* * "value" is the Epoch-relative time of 00:00:00 GMT 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 GMT. */
	return value + rulep->r_time + offset;
}

/*
** Given a POSIX section 8-style TZ string, fill in the rule tables as
** appropriate.
*/

static int
tzparse(name, sp, lastditch)
  const char *name;
  register struct state *const sp;
  const int lastditch;
{
	const char *stdname;
	const char *dstname;
	int stdlen;
	int dstlen;
	long stdoffset;
	long dstoffset;
	register time_t *atp;
	register unsigned char *typep;
	register char *cp;
	register 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;
	} else {
		name = getzname(name);
		stdlen = name - stdname;
		if (stdlen < 3)
			return -1;
	}
	if (*name == '\0')
		return -1;
	else {
		name = getoffset(name, &stdoffset);
		if (name == NULL)
			return -1;
	}
	load_result = tzload(TZDEFRULES, sp);
	if (load_result != 0)
		sp->leapcnt = 0;		/* so, we're off a little */
	if (*name != '\0') {
		dstname = name;
		name = getzname(name);
		dstlen = name - dstname;/* length of DST zone name */
		if (dstlen < 3)
			return -1;
		if (*name != '\0' && *name != ',' && *name != ';') {
			name = getoffset(name, &dstoffset);
			if (name == NULL)
				return -1;
		} else
			dstoffset = stdoffset - SECSPERHOUR;
		if (*name == ',' || *name == ';') {
			struct rule start;
			struct rule end;
			register int year;
			register 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 to 2037. */
			sp->timecnt = 2 * (2037 - EPOCH_YEAR + 1);
			if (sp->timecnt > TZ_MAX_TIMES)
				return -1;
			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;
			for (year = EPOCH_YEAR; year <= 2037; ++year) {
				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 */
				}
				janfirst +=
					year_lengths[isleap(year)] * SECSPERDAY;
			}
		} else {
			int sawstd;
			int sawdst;
			long stdfix;
			long dstfix;
			long oldfix;
			int isdst;
			register int i;

			if (*name != '\0')
				return -1;
			if (load_result != 0)
				return -1;
			/* * Compute the difference between the real and * prototype
			 * standard and summer time offsets * from GMT, and put the real
			 * standard and summer * time offsets into the rules in place of
			 * the * prototype offsets. */
			sawstd = FALSE;
			sawdst = FALSE;
			stdfix = 0;
			dstfix = 0;
			for (i = 0; i < sp->typecnt; ++i) {
				if (sp->ttis[i].tt_isdst) {
					oldfix = dstfix;
					dstfix =
						sp->ttis[i].tt_gmtoff + dstoffset;
					if (sawdst && (oldfix != dstfix))
						return -1;
					sp->ttis[i].tt_gmtoff = -dstoffset;
					sp->ttis[i].tt_abbrind = stdlen + 1;
					sawdst = TRUE;
				} else {
					oldfix = stdfix;
					stdfix =
						sp->ttis[i].tt_gmtoff + stdoffset;
					if (sawstd && (oldfix != stdfix))
						return -1;
					sp->ttis[i].tt_gmtoff = -stdoffset;
					sp->ttis[i].tt_abbrind = 0;
					sawstd = TRUE;
				}
			}
			/* * Make sure we have both standard and summer time. */
			if (!sawdst || !sawstd)
				return -1;
			/* * Now correct the transition times by shifting * them by the
			 * difference between the real and * prototype offsets.  Note
			 * that this difference * can be different in standard and summer
			 * time; * the prototype probably has a 1-hour difference *
			 * between standard and summer time, but a different * difference
			 * can be specified in TZ. */
			isdst = FALSE;		/* we start in standard time */
			for (i = 0; i < sp->timecnt; ++i) {
				register const struct ttinfo *ttisp;

				/* * 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. */
				ttisp = &sp->ttis[sp->types[i]];
				sp->ats[i] +=
					(isdst && !ttisp->tt_ttisstd) ?
					dstfix : stdfix;
				isdst = ttisp->tt_isdst;
			}
		}
	} 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 (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 void
gmtload(sp)
  struct state *const sp;
{
	if (tzload(GMT, sp) != 0)
		(void) tzparse(GMT, sp, TRUE);
}

void
tzset()
{
	register const char *name;
	void tzsetwall();

	name = getenv("TZ");
	if (name == NULL) {
		tzsetwall();
		return;
	}
	lcl_is_set = TRUE;
#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = (struct state *) malloc(sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();		/* all we can do */
			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->ttis[0].tt_gmtoff = 0;
		lclptr->ttis[0].tt_abbrind = 0;
		(void) strcpy(lclptr->chars, GMT);
	} else if (tzload(name, lclptr) != 0)
		if (name[0] == ':' || tzparse(name, lclptr, FALSE) != 0)
			(void) gmtload(lclptr);
	settzname();
}

void
tzsetwall()
{
	lcl_is_set = TRUE;
#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = (struct state *) malloc(sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();		/* all we can do */
			return;
		}
	}
#endif /* defined ALL_STATE */
	if (tzload((char *) NULL, lclptr) != 0)
		gmtload(lclptr);
	settzname();
}

/*
** 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 void
localsub(timep, offset, tmp)
  const time_t *const timep;
  const long offset;
  struct tm *const tmp;
{
	register const struct state *sp;
	register const struct ttinfo *ttisp;
	register int i;
	const time_t t = *timep;

	if (!lcl_is_set)
		tzset();
	sp = lclptr;
#ifdef ALL_STATE
	if (sp == NULL) {
		gmtsub(timep, offset, tmp);
		return;
	}
#endif /* defined ALL_STATE */
	if (sp->timecnt == 0 || t < sp->ats[0]) {
		i = 0;
		while (sp->ttis[i].tt_isdst)
			if (++i >= sp->typecnt) {
				i = 0;
				break;
			}
	} else {
		for (i = 1; i < sp->timecnt; ++i)
			if (t < sp->ats[i])
				break;
		i = sp->types[i - 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); */
	timesub(&t, ttisp->tt_gmtoff, sp, tmp);
	tmp->tm_isdst = ttisp->tt_isdst;
	tzname[tmp->tm_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
	tmp->tm_zone = &sp->chars[ttisp->tt_abbrind];
}

struct tm *
localtime(timep)
  const time_t *const timep;
{
	static struct tm tm;

	localsub(timep, 0L, &tm);
	return &tm;
}

/*
** gmtsub is to gmtime as localsub is to localtime.
*/

static void
gmtsub(timep, offset, tmp)
  const time_t *const timep;
  const long offset;
  struct tm *const tmp;
{
	if (!gmt_is_set) {
		gmt_is_set = TRUE;
#ifdef ALL_STATE
		gmtptr = (struct state *) malloc(sizeof *gmtptr);
		if (gmtptr != NULL)
#endif /* defined ALL_STATE */
			gmtload(gmtptr);
	}
	timesub(timep, offset, gmtptr, tmp);
	/* * Could get fancy here and deliver something such as * "GMT+xxxx" or
	 * "GMT-xxxx" if offset is non-zero, * but this is no time for a treasure
	 * hunt. */
	if (offset != 0)
		tmp->tm_zone = WILDABBR;
	else {
#ifdef ALL_STATE
		if (gmtptr == NULL)
			tmp->TM_ZONE = GMT;
		else
			tmp->TM_ZONE = gmtptr->chars;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
		tmp->tm_zone = gmtptr->chars;
#endif /* State Farm */
	}
}

struct tm *
gmtime(timep)
  const time_t *const timep;
{
	static struct tm tm;

	gmtsub(timep, 0L, &tm);
	return &tm;
}

static void
timesub(timep, offset, sp, tmp)
  const time_t *const timep;
  const long offset;
  register const struct state *const sp;
  register struct tm *const tmp;
{
	register const struct lsinfo *lp;
	register long days;
	register long rem;
	register int y;
	register int yleap;
	register const int *ip;
	register long corr;
	register int hit;
	register int i;

	corr = 0;
	hit = FALSE;
#ifdef ALL_STATE
	i = (sp == NULL) ? 0 : sp->leapcnt;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
	i = sp->leapcnt;
#endif /* State Farm */
	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);
			corr = lp->ls_corr;
			break;
		}
	}
	days = *timep / SECSPERDAY;
	rem = *timep % SECSPERDAY;
#ifdef mc68k
	if (*timep == 0x80000000) {
		/* * A 3B1 muffs the division on the most negative number. */
		days = -24855;
		rem = -11648;
	}
#endif /* mc68k */
	rem += (offset - corr);
	while (rem < 0) {
		rem += SECSPERDAY;
		--days;
	}
	while (rem >= SECSPERDAY) {
		rem -= SECSPERDAY;
		++days;
	}
	tmp->tm_hour = (int) (rem / SECSPERHOUR);
	rem = rem % SECSPERHOUR;
	tmp->tm_min = (int) (rem / SECSPERMIN);
	tmp->tm_sec = (int) (rem % SECSPERMIN);
	if (hit)
		/* * A positive leap second requires a special * representation. This
		 * uses "... ??:59:60". */
		++(tmp->tm_sec);
	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
	if (tmp->tm_wday < 0)
		tmp->tm_wday += DAYSPERWEEK;
	y = EPOCH_YEAR;
	if (days >= 0)
		for (;;) {
			yleap = isleap(y);
			if (days < (long) year_lengths[yleap])
				break;
			++y;
			days = days - (long) year_lengths[yleap];
	} else
		do {
			--y;
			yleap = isleap(y);
			days = days + (long) year_lengths[yleap];
		} while (days < 0);
	tmp->tm_year = y - TM_YEAR_BASE;
	tmp->tm_yday = (int) days;
	ip = mon_lengths[yleap];
	for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
		days = days - (long) ip[tmp->tm_mon];
	tmp->tm_mday = (int) (days + 1);
	tmp->tm_isdst = 0;
	tmp->tm_gmtoff = offset;
}

/*
** A la X3J11
*/

char *
asctime(timeptr)
  register const struct tm *timeptr;
{
	static const char wday_name[DAYSPERWEEK][3] =
	{
		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
	};
	static const char mon_name[MONSPERYEAR][3] =
	{
		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
	};
	static char result[26];

	(void) sprintf(result, "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %d\n",
				   wday_name[timeptr->tm_wday],
				   mon_name[timeptr->tm_mon],
				   timeptr->tm_mday, timeptr->tm_hour,
				   timeptr->tm_min, timeptr->tm_sec,
				   TM_YEAR_BASE + timeptr->tm_year);
	return result;
}

char *
ctime(timep)
  const time_t *const timep;
{
	return asctime(localtime(timep));
}

/*
** 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. (mtxinu!kridle now).
**	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 /* !defined WRONG */

static void
normalize(tensptr, unitsptr, base)
  int *const tensptr;
  int *const unitsptr;
  const int base;
{
	if (*unitsptr >= base) {
		*tensptr += *unitsptr / base;
		*unitsptr %= base;
	} else if (*unitsptr < 0) {
		--*tensptr;
		*unitsptr += base;
		if (*unitsptr < 0) {
			*tensptr -= 1 + (-*unitsptr) / base;
			*unitsptr = base - (-*unitsptr) % base;
		}
	}
}

static int
tmcomp(atmp, btmp)
  register const struct tm *const atmp;
  register const struct tm *const btmp;
{
	register int result;

	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
		(result = (atmp->tm_min - btmp->tm_min)) == 0)
		result = atmp->tm_sec - btmp->tm_sec;
	return result;
}

static time_t
time2(tmp, funcp, offset, okayp)
  struct tm *const tmp;
  void (*const funcp) ();
  const long offset;
  int *const okayp;
{
	register const struct state *sp;
	register int dir;
	register int bits;
	register int i,
	  j;
	register int saved_seconds;
	time_t newt;
	time_t t;
	struct tm yourtm,
	  mytm;

	*okayp = FALSE;
	yourtm = *tmp;
	if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
		normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
	normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
	normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
	normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
	while (yourtm.tm_mday <= 0) {
		--yourtm.tm_year;
		yourtm.tm_mday +=
			year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
	}
	for (;;) {
		i = mon_lengths[isleap(yourtm.tm_year +
							   TM_YEAR_BASE)][yourtm.tm_mon];
		if (yourtm.tm_mday <= i)
			break;
		yourtm.tm_mday -= i;
		if (++yourtm.tm_mon >= MONSPERYEAR) {
			yourtm.tm_mon = 0;
			++yourtm.tm_year;
		}
	}
	saved_seconds = yourtm.tm_sec;
	yourtm.tm_sec = 0;
	/* * Calculate the number of magnitude bits in a time_t * (this works
	 * regardless of whether time_t is * signed or unsigned, though lint
	 * complains if unsigned). */
	for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) ;
	/* * If time_t is signed, then 0 is the median value, * if time_t is
	 * unsigned, then 1 << bits is median. */
	t = (t < 0) ? 0 : ((time_t) 1 << bits);
	for (;;) {
		(*funcp) (&t, offset, &mytm);
		dir = tmcomp(&mytm, &yourtm);
		if (dir != 0) {
			if (bits-- < 0)
				return WRONG;
			if (bits < 0)
				--t;
			else if (dir > 0)
				t -= (time_t) 1 << bits;
			else
				t += (time_t) 1 << bits;
			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 = 0; i < sp->typecnt; ++i) {
			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
				continue;
			for (j = 0; j < sp->typecnt; ++j) {
				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
					continue;
				newt = t + sp->ttis[j].tt_gmtoff -
					sp->ttis[i].tt_gmtoff;
				(*funcp) (&newt, offset, &mytm);
				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:
	t += saved_seconds;
	(*funcp) (&t, offset, tmp);
	*okayp = TRUE;
	return t;
}

static time_t
time1(tmp, funcp, offset)
  struct tm *const tmp;
  void (*const funcp) ();
  const long offset;
{
	register time_t t;
	register const struct state *sp;
	register int samei,
	  otheri;
	int okay;

	if (tmp->tm_isdst > 1)
		tmp->tm_isdst = 1;
	t = time2(tmp, funcp, offset, &okay);
	if (okay || tmp->tm_isdst < 0)
		return t;
	/* * 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 (samei = 0; samei < sp->typecnt; ++samei) {
		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
			continue;
		for (otheri = 0; otheri < sp->typecnt; ++otheri) {
			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;
}

time_t
mktime(tmp)
  struct tm *const tmp;
{
	return time1(tmp, localsub, 0L);
}
