/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/

/*
** Leap second handling from Bradley White.
** POSIX-style TZ environment variable handling from Guy Harris.
*/

/*LINTLIBRARY*/

#define LOCALTIME_IMPLEMENTATION
#include "private.h"

#include "tzfile.h"
#include <fcntl.h>

#if defined THREAD_SAFE && THREAD_SAFE
# include <pthread.h>
static pthread_mutex_t locallock = PTHREAD_MUTEX_INITIALIZER;
static int lock(void) { return pthread_mutex_lock(&locallock); }
static void unlock(void) { pthread_mutex_unlock(&locallock); }
#else
static int lock(void) { return 0; }
static void unlock(void) { }
#endif

/* NETBSD_INSPIRED_EXTERN functions are exported to callers if
   NETBSD_INSPIRED is defined, and are private otherwise.  */
#if NETBSD_INSPIRED
# define NETBSD_INSPIRED_EXTERN
#else
# define NETBSD_INSPIRED_EXTERN static
#endif

#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 */

/*
** SunOS 4.1.1 headers lack O_BINARY.
*/

#ifdef O_BINARY
#define OPEN_MODE	(O_RDONLY | O_BINARY)
#endif /* defined O_BINARY */
#ifndef O_BINARY
#define OPEN_MODE	O_RDONLY
#endif /* !defined O_BINARY */

#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 */

static const char	wildabbr[] = WILDABBR;

static const char	gmt[] = "GMT";

/*
** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
** Default to US rules as of 2017-05-07.
** 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 ",M3.2.0,M11.1.0"
#endif

struct ttinfo {				/* time type information */
	int_fast32_t	tt_gmtoff;	/* UT offset in seconds */
	bool		tt_isdst;	/* used to set tm_isdst */
	int		tt_abbrind;	/* abbreviation list index */
	bool		tt_ttisstd;	/* transition is std time */
	bool		tt_ttisgmt;	/* transition is UT */
};

struct lsinfo {				/* leap second information */
	time_t		ls_trans;	/* transition time */
	int_fast64_t	ls_corr;	/* correction to apply */
};

#define SMALLEST(a, b)	(((a) < (b)) ? (a) : (b))
#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;
	bool		goback;
	bool		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];
	int		defaulttype; /* for early times or if no transitions */
};

enum r_type {
  JULIAN_DAY,		/* Jn = Julian day */
  DAY_OF_YEAR,		/* n = day of year */
  MONTH_NTH_DAY_OF_WEEK	/* Mm.n.d = month, week, day of week */
};

struct rule {
	enum r_type	r_type;		/* type of rule */
	int		r_day;		/* day number of rule */
	int		r_week;		/* week number of rule */
	int		r_mon;		/* month number of rule */
	int_fast32_t	r_time;		/* transition time of rule */
};

static struct tm *gmtsub(struct state const *, time_t const *, int_fast32_t,
			 struct tm *);
static bool increment_overflow(int *, int);
static bool increment_overflow_time(time_t *, int_fast32_t);
static bool normalize_overflow32(int_fast32_t *, int *, int);
static struct tm *timesub(time_t const *, int_fast32_t, struct state const *,
			  struct tm *);
static bool typesequiv(struct state const *, int, int);
static bool tzparse(char const *, struct state *, bool);

#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 */

#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX 255
#endif /* !defined TZ_STRLEN_MAX */

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

/*
** Section 4.12.3 of X3.159-1989 requires that
**	Except for the strftime function, these functions [asctime,
**	ctime, gmtime, localtime] return values in one of two static
**	objects: a broken-down time structure and an array of char.
** Thanks to Paul Eggert for noting this.
*/

static struct tm	tm;

#if !HAVE_POSIX_DECLS || TZ_TIME_T
# if HAVE_TZNAME
char *			tzname[2] = {
	(char *) wildabbr,
	(char *) wildabbr
};
# endif
# if USG_COMPAT
long			timezone;
int			daylight;
# endif
# ifdef ALTZONE
long			altzone;
# endif
#endif

/* Initialize *S to a value based on GMTOFF, ISDST, and ABBRIND.  */
static void
init_ttinfo(struct ttinfo *s, int_fast32_t gmtoff, bool isdst, int abbrind)
{
  s->tt_gmtoff = gmtoff;
  s->tt_isdst = isdst;
  s->tt_abbrind = abbrind;
  s->tt_ttisstd = false;
  s->tt_ttisgmt = false;
}

static int_fast32_t
detzcode(const char *const codep)
{
	register int_fast32_t	result;
	register int		i;
	int_fast32_t one = 1;
	int_fast32_t halfmaxval = one << (32 - 2);
	int_fast32_t maxval = halfmaxval - 1 + halfmaxval;
	int_fast32_t minval = -1 - maxval;

	result = codep[0] & 0x7f;
	for (i = 1; i < 4; ++i)
		result = (result << 8) | (codep[i] & 0xff);

	if (codep[0] & 0x80) {
	  /* Do two's-complement negation even on non-two's-complement machines.
	     If the result would be minval - 1, return minval.  */
	  result -= !TWOS_COMPLEMENT(int_fast32_t) && result != 0;
	  result += minval;
	}
	return result;
}

static int_fast64_t
detzcode64(const char *const codep)
{
	register uint_fast64_t result;
	register int	i;
	int_fast64_t one = 1;
	int_fast64_t halfmaxval = one << (64 - 2);
	int_fast64_t maxval = halfmaxval - 1 + halfmaxval;
	int_fast64_t minval = -TWOS_COMPLEMENT(int_fast64_t) - maxval;

	result = codep[0] & 0x7f;
	for (i = 1; i < 8; ++i)
		result = (result << 8) | (codep[i] & 0xff);

	if (codep[0] & 0x80) {
	  /* Do two's-complement negation even on non-two's-complement machines.
	     If the result would be minval - 1, return minval.  */
	  result -= !TWOS_COMPLEMENT(int_fast64_t) && result != 0;
	  result += minval;
	}
	return result;
}

static void
update_tzname_etc(struct state const *sp, struct ttinfo const *ttisp)
{
#if HAVE_TZNAME
  tzname[ttisp->tt_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
#endif
#if USG_COMPAT
  if (!ttisp->tt_isdst)
    timezone = - ttisp->tt_gmtoff;
#endif
#ifdef ALTZONE
  if (ttisp->tt_isdst)
    altzone = - ttisp->tt_gmtoff;
#endif
}

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

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

static void
scrub_abbrs(struct state *sp)
{
	int i;
	/*
	** 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 &&
			strcmp(cp, GRANDPARENTED) != 0)
				*(cp + TZ_ABBR_MAX_LEN) = '\0';
	}
}

static bool
differ_by_repeat(const time_t t1, const time_t t0)
{
	if (TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
		return 0;
	return t1 - t0 == SECSPERREPEAT;
}

/* Input buffer for data read from a compiled tz file.  */
union input_buffer {
  /* The first part of the buffer, interpreted as a header.  */
  struct tzhead tzhead;

  /* The entire buffer.  */
  char buf[2 * sizeof(struct tzhead) + 2 * sizeof (struct state)
	   + 4 * TZ_MAX_TIMES];
};

/* TZDIR with a trailing '/' rather than a trailing '\0'.  */
static char const tzdirslash[sizeof TZDIR] = TZDIR "/";

/* Local storage needed for 'tzloadbody'.  */
union local_storage {
  /* The results of analyzing the file's contents after it is opened.  */
  struct file_analysis {
    /* The input buffer.  */
    union input_buffer u;

    /* A temporary state used for parsing a TZ string in the file.  */
    struct state st;
  } u;

  /* The file name to be opened.  */
  char fullname[BIGGEST(sizeof (struct file_analysis),
			sizeof tzdirslash + 1024)];
};

/* Load tz data from the file named NAME into *SP.  Read extended
   format if DOEXTEND.  Use *LSP for temporary storage.  Return 0 on
   success, an errno value on failure.  */
static int
tzloadbody(char const *name, struct state *sp, bool doextend,
	   union local_storage *lsp)
{
	register int			i;
	register int			fid;
	register int			stored;
	register ssize_t		nread;
	register bool doaccess;
	register union input_buffer *up = &lsp->u.u;
	register int tzheadsize = sizeof (struct tzhead);

	sp->goback = sp->goahead = false;

	if (! name) {
		name = TZDEFAULT;
		if (! name)
		  return EINVAL;
	}

	if (name[0] == ':')
		++name;
	doaccess = name[0] == '/';
	if (!doaccess) {
		size_t namelen = strlen(name);
		if (sizeof lsp->fullname - sizeof tzdirslash <= namelen)
		  return ENAMETOOLONG;

		/* Create a string "TZDIR/NAME".  Using sprintf here
		   would pull in stdio (and would fail if the
		   resulting string length exceeded INT_MAX!).  */
		memcpy(lsp->fullname, tzdirslash, sizeof tzdirslash);
		strcpy(lsp->fullname + sizeof tzdirslash, name);

		/* Set doaccess if '.' (as in "../") shows up in name.  */
		if (strchr(name, '.'))
			doaccess = true;
		name = lsp->fullname;
	}
	if (doaccess && access(name, R_OK) != 0)
	  return errno;
	fid = open(name, OPEN_MODE);
	if (fid < 0)
	  return errno;

	nread = read(fid, up->buf, sizeof up->buf);
	if (nread < tzheadsize) {
	  int err = nread < 0 ? errno : EINVAL;
	  close(fid);
	  return err;
	}
	if (close(fid) < 0)
	  return errno;
	for (stored = 4; stored <= 8; stored *= 2) {
		int_fast32_t ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt);
		int_fast32_t ttisgmtcnt = detzcode(up->tzhead.tzh_ttisgmtcnt);
		int_fast64_t prevtr = 0;
		int_fast32_t prevcorr = 0;
		int_fast32_t leapcnt = detzcode(up->tzhead.tzh_leapcnt);
		int_fast32_t timecnt = detzcode(up->tzhead.tzh_timecnt);
		int_fast32_t typecnt = detzcode(up->tzhead.tzh_typecnt);
		int_fast32_t charcnt = detzcode(up->tzhead.tzh_charcnt);
		char const *p = up->buf + tzheadsize;
		if (! (0 <= leapcnt && leapcnt < TZ_MAX_LEAPS
		       && 0 < typecnt && typecnt < TZ_MAX_TYPES
		       && 0 <= timecnt && timecnt < TZ_MAX_TIMES
		       && 0 <= charcnt && charcnt < TZ_MAX_CHARS
		       && (ttisstdcnt == typecnt || ttisstdcnt == 0)
		       && (ttisgmtcnt == typecnt || ttisgmtcnt == 0)))
		  return EINVAL;
		if (nread
		    < (tzheadsize		/* struct tzhead */
		       + timecnt * stored	/* ats */
		       + timecnt		/* types */
		       + typecnt * 6		/* ttinfos */
		       + charcnt		/* chars */
		       + leapcnt * (stored + 4)	/* lsinfos */
		       + ttisstdcnt		/* ttisstds */
		       + ttisgmtcnt))		/* ttisgmts */
		  return EINVAL;
		sp->leapcnt = leapcnt;
		sp->timecnt = timecnt;
		sp->typecnt = typecnt;
		sp->charcnt = charcnt;

		/* Read transitions, discarding those out of time_t range.
		   But pretend the last transition before TIME_T_MIN
		   occurred at TIME_T_MIN.  */
		timecnt = 0;
		for (i = 0; i < sp->timecnt; ++i) {
			int_fast64_t at
			  = stored == 4 ? detzcode(p) : detzcode64(p);
			sp->types[i] = at <= TIME_T_MAX;
			if (sp->types[i]) {
			  time_t attime
			    = ((TYPE_SIGNED(time_t) ? at < TIME_T_MIN : at < 0)
			       ? TIME_T_MIN : at);
			  if (timecnt && attime <= sp->ats[timecnt - 1]) {
			    if (attime < sp->ats[timecnt - 1])
			      return EINVAL;
			    sp->types[i - 1] = 0;
			    timecnt--;
			  }
			  sp->ats[timecnt++] = attime;
			}
			p += stored;
		}

		timecnt = 0;
		for (i = 0; i < sp->timecnt; ++i) {
			unsigned char typ = *p++;
			if (sp->typecnt <= typ)
			  return EINVAL;
			if (sp->types[i])
				sp->types[timecnt++] = typ;
		}
		sp->timecnt = timecnt;
		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *	ttisp;
			unsigned char isdst, abbrind;

			ttisp = &sp->ttis[i];
			ttisp->tt_gmtoff = detzcode(p);
			p += 4;
			isdst = *p++;
			if (! (isdst < 2))
			  return EINVAL;
			ttisp->tt_isdst = isdst;
			abbrind = *p++;
			if (! (abbrind < sp->charcnt))
			  return EINVAL;
			ttisp->tt_abbrind = abbrind;
		}
		for (i = 0; i < sp->charcnt; ++i)
			sp->chars[i] = *p++;
		sp->chars[i] = '\0';	/* ensure '\0' at end */

		/* Read leap seconds, discarding those out of time_t range.  */
		leapcnt = 0;
		for (i = 0; i < sp->leapcnt; ++i) {
		  int_fast64_t tr = stored == 4 ? detzcode(p) : detzcode64(p);
		  int_fast32_t corr = detzcode(p + stored);
		  p += stored + 4;
		  /* Leap seconds cannot occur before the Epoch.  */
		  if (tr < 0)
		    return EINVAL;
		  if (tr <= TIME_T_MAX) {
		    /* Leap seconds cannot occur more than once per UTC month,
		       and UTC months are at least 28 days long (minus 1
		       second for a negative leap second).  Each leap second's
		       correction must differ from the previous one's by 1
		       second.  */
		    if (tr - prevtr < 28 * SECSPERDAY - 1
			|| (corr != prevcorr - 1 && corr != prevcorr + 1))
		      return EINVAL;
		    sp->lsis[leapcnt].ls_trans = prevtr = tr;
		    sp->lsis[leapcnt].ls_corr = prevcorr = corr;
		    leapcnt++;
		  }
		}
		sp->leapcnt = leapcnt;

		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			if (ttisstdcnt == 0)
				ttisp->tt_ttisstd = false;
			else {
				if (*p != true && *p != false)
				  return EINVAL;
				ttisp->tt_ttisstd = *p++;
			}
		}
		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			if (ttisgmtcnt == 0)
				ttisp->tt_ttisgmt = false;
			else {
				if (*p != true && *p != false)
						return EINVAL;
				ttisp->tt_ttisgmt = *p++;
			}
		}
		/*
		** If this is an old file, we're done.
		*/
		if (up->tzhead.tzh_version[0] == '\0')
			break;
		nread -= p - up->buf;
		memmove(up->buf, p, nread);
	}
	if (doextend && nread > 2 &&
		up->buf[0] == '\n' && up->buf[nread - 1] == '\n' &&
		sp->typecnt + 2 <= TZ_MAX_TYPES) {
			struct state	*ts = &lsp->u.st;

			up->buf[nread - 1] = '\0';
			if (tzparse(&up->buf[1], ts, false)
			    && ts->typecnt == 2) {

			  /* Attempt to reuse existing abbreviations.
			     Without this, America/Anchorage would be right on
			     the edge after 2037 when TZ_MAX_CHARS is 50, as
			     sp->charcnt equals 40 (for LMT AST AWT APT AHST
			     AHDT YST AKDT AKST) and ts->charcnt equals 10
			     (for AKST AKDT).  Reusing means sp->charcnt can
			     stay 40 in this example.  */
			  int gotabbr = 0;
			  int charcnt = sp->charcnt;
			  for (i = 0; i < 2; i++) {
			    char *tsabbr = ts->chars + ts->ttis[i].tt_abbrind;
			    int j;
			    for (j = 0; j < charcnt; j++)
			      if (strcmp(sp->chars + j, tsabbr) == 0) {
				ts->ttis[i].tt_abbrind = j;
				gotabbr++;
				break;
			      }
			    if (! (j < charcnt)) {
			      int tsabbrlen = strlen(tsabbr);
			      if (j + tsabbrlen < TZ_MAX_CHARS) {
				strcpy(sp->chars + j, tsabbr);
				charcnt = j + tsabbrlen + 1;
				ts->ttis[i].tt_abbrind = j;
				gotabbr++;
			      }
			    }
			  }
			  if (gotabbr == 2) {
			    sp->charcnt = charcnt;

			    /* Ignore any trailing, no-op transitions generated
			       by zic as they don't help here and can run afoul
			       of bugs in zic 2016j or earlier.  */
			    while (1 < sp->timecnt
				   && (sp->types[sp->timecnt - 1]
				       == sp->types[sp->timecnt - 2]))
			      sp->timecnt--;

			    for (i = 0; i < ts->timecnt; i++)
			      if (sp->ats[sp->timecnt - 1] < ts->ats[i])
				break;
			    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];
			  }
			}
	}
	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 = true;
					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 = true;
					break;
		}
	}
	/*
	** If type 0 is unused in transitions,
	** it's the type to use for early times.
	*/
	for (i = 0; i < sp->timecnt; ++i)
		if (sp->types[i] == 0)
			break;
	i = i < sp->timecnt ? -1 : 0;
	/*
	** Absent the above,
	** if there are transition times
	** and the first transition is to a daylight time
	** find the standard type less than and closest to
	** the type of the first transition.
	*/
	if (i < 0 && sp->timecnt > 0 && sp->ttis[sp->types[0]].tt_isdst) {
		i = sp->types[0];
		while (--i >= 0)
			if (!sp->ttis[i].tt_isdst)
				break;
	}
	/*
	** If no result yet, find the first standard type.
	** If there is none, punt to type zero.
	*/
	if (i < 0) {
		i = 0;
		while (sp->ttis[i].tt_isdst)
			if (++i >= sp->typecnt) {
				i = 0;
				break;
			}
	}
	sp->defaulttype = i;
	return 0;
}

/* Load tz data from the file named NAME into *SP.  Read extended
   format if DOEXTEND.  Return 0 on success, an errno value on failure.  */
static int
tzload(char const *name, struct state *sp, bool doextend)
{
#ifdef ALL_STATE
  union local_storage *lsp = malloc(sizeof *lsp);
  if (!lsp)
    return errno;
  else {
    int err = tzloadbody(name, sp, doextend, lsp);
    free(lsp);
    return err;
  }
#else
  union local_storage ls;
  return tzloadbody(name, sp, doextend, &ls);
#endif
}

static bool
typesequiv(const struct state *sp, int a, int b)
{
	register bool result;

	if (sp == NULL ||
		a < 0 || a >= sp->typecnt ||
		b < 0 || b >= sp->typecnt)
			result = false;
	else {
		register const struct ttinfo *	ap = &sp->ttis[a];
		register const struct ttinfo *	bp = &sp->ttis[b];
		result = 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;
	}
	return result;
}

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(register const char *strp)
{
	register 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(register const char *strp, int *const nump, const int min, const int max)
{
	register char	c;
	register 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(register const char *strp, int_fast32_t *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 * (int_fast32_t) 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(register const char *strp, int_fast32_t *const offsetp)
{
	register bool neg = false;

	if (*strp == '-') {
		neg = true;
		++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, 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 (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 = getoffset(strp, &rulep->r_time);
	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
	return strp;
}

/*
** Given a year, a rule, and the offset from UT at the time that rule takes
** effect, calculate the year-relative time that rule takes effect.
*/

static int_fast32_t
transtime(const int year, register const struct rule *const rulep,
	  const int_fast32_t offset)
{
	register bool	leapyear;
	register int_fast32_t value;
	register int	i;
	int		d, m1, yy0, yy1, yy2, dow;

	INITIALIZE(value);
	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 = (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 = rulep->r_day * SECSPERDAY;
		break;

	case MONTH_NTH_DAY_OF_WEEK:
		/*
		** Mm.n.d - nth "dth day" of month m.
		*/

		/*
		** 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;
		for (i = 0; i < rulep->r_mon - 1; ++i)
			value += mon_lengths[leapyear][i] * SECSPERDAY;
		break;
	}

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

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

static bool
tzparse(const char *name, struct state *sp, bool lastditch)
{
	const char *			stdname;
	const char *			dstname;
	size_t				stdlen;
	size_t				dstlen;
	size_t				charcnt;
	int_fast32_t			stdoffset;
	int_fast32_t			dstoffset;
	register char *			cp;
	register bool			load_ok;

	stdname = name;
	if (lastditch) {
		stdlen = sizeof gmt - 1;
		name += stdlen;
		stdoffset = 0;
	} else {
		if (*name == '<') {
			name++;
			stdname = name;
			name = getqzname(name, '>');
			if (*name != '>')
			  return false;
			stdlen = name - stdname;
			name++;
		} else {
			name = getzname(name);
			stdlen = name - stdname;
		}
		if (!stdlen)
		  return false;
		name = getoffset(name, &stdoffset);
		if (name == NULL)
		  return false;
	}
	charcnt = stdlen + 1;
	if (sizeof sp->chars < charcnt)
	  return false;
	load_ok = tzload(TZDEFRULES, sp, false) == 0;
	if (!load_ok)
		sp->leapcnt = 0;		/* so, we're off a little */
	if (*name != '\0') {
		if (*name == '<') {
			dstname = ++name;
			name = getqzname(name, '>');
			if (*name != '>')
			  return false;
			dstlen = name - dstname;
			name++;
		} else {
			dstname = name;
			name = getzname(name);
			dstlen = name - dstname; /* length of DST zone name */
		}
		if (!dstlen)
		  return false;
		charcnt += dstlen + 1;
		if (sizeof sp->chars < charcnt)
		  return false;
		if (*name != '\0' && *name != ',' && *name != ';') {
			name = getoffset(name, &dstoffset);
			if (name == NULL)
			  return false;
		} else	dstoffset = stdoffset - SECSPERHOUR;
		if (*name == '\0' && !load_ok)
			name = TZDEFRULESTRING;
		if (*name == ',' || *name == ';') {
			struct rule	start;
			struct rule	end;
			register int	year;
			register int	yearlim;
			register int	timecnt;
			time_t		janfirst;
			int_fast32_t janoffset = 0;
			int yearbeg;

			++name;
			if ((name = getrule(name, &start)) == NULL)
			  return false;
			if (*name++ != ',')
			  return false;
			if ((name = getrule(name, &end)) == NULL)
			  return false;
			if (*name != '\0')
			  return false;
			sp->typecnt = 2;	/* standard time and DST */
			/*
			** Two transitions per year, from EPOCH_YEAR forward.
			*/
			init_ttinfo(&sp->ttis[0], -dstoffset, true, stdlen + 1);
			init_ttinfo(&sp->ttis[1], -stdoffset, false, 0);
			sp->defaulttype = 0;
			timecnt = 0;
			janfirst = 0;
			yearbeg = EPOCH_YEAR;

			do {
			  int_fast32_t yearsecs
			    = year_lengths[isleap(yearbeg - 1)] * SECSPERDAY;
			  yearbeg--;
			  if (increment_overflow_time(&janfirst, -yearsecs)) {
			    janoffset = -yearsecs;
			    break;
			  }
			} while (EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg);

			yearlim = yearbeg + YEARSPERREPEAT + 1;
			for (year = yearbeg; year < yearlim; year++) {
				int_fast32_t
				  starttime = transtime(year, &start, stdoffset),
				  endtime = transtime(year, &end, dstoffset);
				int_fast32_t
				  yearsecs = (year_lengths[isleap(year)]
					      * SECSPERDAY);
				bool reversed = endtime < starttime;
				if (reversed) {
					int_fast32_t swap = starttime;
					starttime = endtime;
					endtime = swap;
				}
				if (reversed
				    || (starttime < endtime
					&& (endtime - starttime
					    < (yearsecs
					       + (stdoffset - dstoffset))))) {
					if (TZ_MAX_TIMES - 2 < timecnt)
						break;
					sp->ats[timecnt] = janfirst;
					if (! increment_overflow_time
					    (&sp->ats[timecnt],
					     janoffset + starttime))
					  sp->types[timecnt++] = reversed;
					else if (janoffset)
					  sp->defaulttype = reversed;
					sp->ats[timecnt] = janfirst;
					if (! increment_overflow_time
					    (&sp->ats[timecnt],
					     janoffset + endtime)) {
					  sp->types[timecnt++] = !reversed;
					  yearlim = year + YEARSPERREPEAT + 1;
					} else if (janoffset)
					  sp->defaulttype = !reversed;
				}
				if (increment_overflow_time
				    (&janfirst, janoffset + yearsecs))
					break;
				janoffset = 0;
			}
			sp->timecnt = timecnt;
			if (! timecnt)
				sp->typecnt = 1;	/* Perpetual DST.  */
			else if (YEARSPERREPEAT < year - yearbeg)
				sp->goback = sp->goahead = true;
		} else {
			register int_fast32_t	theirstdoffset;
			register int_fast32_t	theirdstoffset;
			register int_fast32_t	theiroffset;
			register bool		isdst;
			register int		i;
			register int		j;

			if (*name != '\0')
			  return false;
			/*
			** 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 = false;
			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.
			*/
			init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
			init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1);
			sp->typecnt = 2;
			sp->defaulttype = 0;
		}
	} else {
		dstlen = 0;
		sp->typecnt = 1;		/* only standard time */
		sp->timecnt = 0;
		init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
		sp->defaulttype = 0;
	}
	sp->charcnt = charcnt;
	cp = sp->chars;
	memcpy(cp, stdname, stdlen);
	cp += stdlen;
	*cp++ = '\0';
	if (dstlen != 0) {
		memcpy(cp, dstname, dstlen);
		*(cp + dstlen) = '\0';
	}
	return true;
}

static void
gmtload(struct state *const sp)
{
	if (tzload(gmt, sp, true) != 0)
		tzparse(gmt, sp, true);
}

/* Initialize *SP to a value appropriate for the TZ setting NAME.
   Return 0 on success, an errno value on failure.  */
static int
zoneinit(struct state *sp, char const *name)
{
  if (name && ! name[0]) {
    /*
    ** User wants it fast rather than right.
    */
    sp->leapcnt = 0;		/* so, we're off a little */
    sp->timecnt = 0;
    sp->typecnt = 0;
    sp->charcnt = 0;
    sp->goback = sp->goahead = false;
    init_ttinfo(&sp->ttis[0], 0, false, 0);
    strcpy(sp->chars, gmt);
    sp->defaulttype = 0;
    return 0;
  } else {
    int err = tzload(name, sp, true);
    if (err != 0 && name && name[0] != ':' && tzparse(name, sp, false))
      err = 0;
    if (err == 0)
      scrub_abbrs(sp);
    return err;
  }
}

static void
tzsetlcl(char const *name)
{
  struct state *sp = lclptr;
  int lcl = name ? strlen(name) < sizeof lcl_TZname : -1;
  if (lcl < 0
      ? lcl_is_set < 0
      : 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0)
    return;
#ifdef ALL_STATE
  if (! sp)
    lclptr = sp = malloc(sizeof *lclptr);
#endif /* defined ALL_STATE */
  if (sp) {
    if (zoneinit(sp, name) != 0)
      zoneinit(sp, "");
    if (0 < lcl)
      strcpy(lcl_TZname, name);
  }
  settzname();
  lcl_is_set = lcl;
}

#ifdef STD_INSPIRED
void
tzsetwall(void)
{
  if (lock() != 0)
    return;
  tzsetlcl(NULL);
  unlock();
}
#endif

static void
tzset_unlocked(void)
{
  tzsetlcl(getenv("TZ"));
}

void
tzset(void)
{
  if (lock() != 0)
    return;
  tzset_unlocked();
  unlock();
}

static void
gmtcheck(void)
{
  static bool gmt_is_set;
  if (lock() != 0)
    return;
  if (! gmt_is_set) {
#ifdef ALL_STATE
    gmtptr = malloc(sizeof *gmtptr);
#endif
    if (gmtptr)
      gmtload(gmtptr);
    gmt_is_set = true;
  }
  unlock();
}

#if NETBSD_INSPIRED

timezone_t
tzalloc(char const *name)
{
  timezone_t sp = malloc(sizeof *sp);
  if (sp) {
    int err = zoneinit(sp, name);
    if (err != 0) {
      free(sp);
      errno = err;
      return NULL;
    }
  }
  return sp;
}

void
tzfree(timezone_t sp)
{
  free(sp);
}

/*
** NetBSD 6.1.4 has ctime_rz, but omit it because POSIX says ctime and
** ctime_r are obsolescent and have potential security problems that
** ctime_rz would share.  Callers can instead use localtime_rz + strftime.
**
** NetBSD 6.1.4 has tzgetname, but omit it because it doesn't work
** in zones with three or more time zone abbreviations.
** Callers can instead use localtime_rz + strftime.
*/

#endif

/*
** 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.)
**
** If successful and SETNAME is nonzero,
** set the applicable parts of tzname, timezone and altzone;
** however, it's OK to omit this step if the time zone is POSIX-compatible,
** since in that case tzset should have already done this step correctly.
** SETNAME's type is intfast32_t for compatibility with gmtsub,
** but it is actually a boolean and its value should be 0 or 1.
*/

/*ARGSUSED*/
static struct tm *
localsub(struct state const *sp, time_t const *timep, int_fast32_t setname,
	 struct tm *const tmp)
{
	register const struct ttinfo *	ttisp;
	register int			i;
	register struct tm *		result;
	const time_t			t = *timep;

	if (sp == NULL) {
	  /* Don't bother to set tzname etc.; tzset has already done it.  */
	  return gmtsub(gmtptr, timep, 0, tmp);
	}
	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		years;

			if (t < sp->ats[0])
				seconds = sp->ats[0] - t;
			else	seconds = t - sp->ats[sp->timecnt - 1];
			--seconds;
			years = (seconds / SECSPERREPEAT + 1) * YEARSPERREPEAT;
			seconds = years * 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(sp, &newt, setname, tmp);
			if (result) {
				register int_fast64_t newy;

				newy = result->tm_year;
				if (t < sp->ats[0])
					newy -= years;
				else	newy += years;
				if (! (INT_MIN <= newy && newy <= INT_MAX))
					return NULL;
				result->tm_year = newy;
			}
			return result;
	}
	if (sp->timecnt == 0 || t < sp->ats[0]) {
		i = sp->defaulttype;
	} 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);
	if (result) {
	  result->tm_isdst = ttisp->tt_isdst;
#ifdef TM_ZONE
	  result->TM_ZONE = (char *) &sp->chars[ttisp->tt_abbrind];
#endif /* defined TM_ZONE */
	  if (setname)
	    update_tzname_etc(sp, ttisp);
	}
	return result;
}

#if NETBSD_INSPIRED

struct tm *
localtime_rz(struct state *sp, time_t const *timep, struct tm *tmp)
{
  return localsub(sp, timep, 0, tmp);
}

#endif

static struct tm *
localtime_tzset(time_t const *timep, struct tm *tmp, bool setname)
{
  int err = lock();
  if (err) {
    errno = err;
    return NULL;
  }
  if (setname || !lcl_is_set)
    tzset_unlocked();
  tmp = localsub(lclptr, timep, setname, tmp);
  unlock();
  return tmp;
}

struct tm *
localtime(const time_t *timep)
{
  return localtime_tzset(timep, &tm, true);
}

struct tm *
localtime_r(const time_t *timep, struct tm *tmp)
{
  return localtime_tzset(timep, tmp, false);
}

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

static struct tm *
gmtsub(struct state const *sp, time_t const *timep, int_fast32_t offset,
       struct tm *tmp)
{
	register struct tm *	result;

	result = timesub(timep, offset, gmtptr, tmp);
#ifdef TM_ZONE
	/*
	** Could get fancy here and deliver something such as
	** "+xx" or "-xx" if offset is non-zero,
	** but this is no time for a treasure hunt.
	*/
	tmp->TM_ZONE = ((char *)
			(offset ? wildabbr : gmtptr ? gmtptr->chars : gmt));
#endif /* defined TM_ZONE */
	return result;
}

/*
* Re-entrant version of gmtime.
*/

struct tm *
gmtime_r(const time_t *timep, struct tm *tmp)
{
  gmtcheck();
  return gmtsub(gmtptr, timep, 0, tmp);
}

struct tm *
gmtime(const time_t *timep)
{
  return gmtime_r(timep, &tm);
}

#ifdef STD_INSPIRED

struct tm *
offtime(const time_t *timep, long offset)
{
  gmtcheck();
  return gmtsub(gmtptr, timep, offset, &tm);
}

#endif /* defined STD_INSPIRED */

/*
** 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_nonneg(int y)
{
  return y / 4 - y / 100 + y / 400;
}

static int
leaps_thru_end_of(register const int y)
{
  return (y < 0
	  ? -1 - leaps_thru_end_of_nonneg(-1 - y)
	  : leaps_thru_end_of_nonneg(y));
}

static struct tm *
timesub(const time_t *timep, int_fast32_t offset,
	const struct state *sp, struct tm *tmp)
{
	register const struct lsinfo *	lp;
	register time_t			tdays;
	register int			idays;	/* unsigned would be so 2003 */
	register int_fast64_t		rem;
	int				y;
	register const int *		ip;
	register int_fast64_t		corr;
	register bool			hit;
	register int			i;

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

		tdelta = tdays / DAYSPERLYEAR;
		if (! ((! TYPE_SIGNED(time_t) || INT_MIN <= tdelta)
		       && tdelta <= INT_MAX))
		  goto out_of_range;
		idelta = tdelta;
		if (idelta == 0)
			idelta = (tdays < 0) ? -1 : 1;
		newy = y;
		if (increment_overflow(&newy, idelta))
		  goto out_of_range;
		leapdays = leaps_thru_end_of(newy - 1) -
			leaps_thru_end_of(y - 1);
		tdays -= ((time_t) newy - y) * DAYSPERNYEAR;
		tdays -= leapdays;
		y = newy;
	}
	/*
	** 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))
		  goto out_of_range;
		idays += year_lengths[isleap(y)];
	}
	while (idays >= year_lengths[isleap(y)]) {
		idays -= year_lengths[isleap(y)];
		if (increment_overflow(&y, 1))
		  goto out_of_range;
	}
	tmp->tm_year = y;
	if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE))
	  goto out_of_range;
	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;
#ifdef TM_GMTOFF
	tmp->TM_GMTOFF = offset;
#endif /* defined TM_GMTOFF */
	return tmp;

 out_of_range:
	errno = EOVERFLOW;
	return NULL;
}

char *
ctime(const time_t *timep)
{
/*
** Section 4.12.3.2 of X3.159-1989 requires that
**	The ctime function converts the calendar time pointed to by timer
**	to local time in the form of a string. It is equivalent to
**		asctime(localtime(timer))
*/
  struct tm *tmp = localtime(timep);
  return tmp ? asctime(tmp) : NULL;
}

char *
ctime_r(const time_t *timep, char *buf)
{
  struct tm mytm;
  struct tm *tmp = localtime_r(timep, &mytm);
  return tmp ? asctime_r(tmp, buf) : NULL;
}

/*
** 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 /* !defined WRONG */

/*
** Normalize logic courtesy Paul Eggert.
*/

static bool
increment_overflow(int *ip, int j)
{
	register int const	i = *ip;

	/*
	** If i >= 0 there can only be overflow if i + j > INT_MAX
	** or if j > INT_MAX - i; given i >= 0, INT_MAX - i cannot overflow.
	** If i < 0 there can only be overflow if i + j < INT_MIN
	** or if j < INT_MIN - i; given i < 0, INT_MIN - i cannot overflow.
	*/
	if ((i >= 0) ? (j > INT_MAX - i) : (j < INT_MIN - i))
		return true;
	*ip += j;
	return false;
}

static bool
increment_overflow32(int_fast32_t *const lp, int const m)
{
	register int_fast32_t const	l = *lp;

	if ((l >= 0) ? (m > INT_FAST32_MAX - l) : (m < INT_FAST32_MIN - l))
		return true;
	*lp += m;
	return false;
}

static bool
increment_overflow_time(time_t *tp, int_fast32_t j)
{
	/*
	** This is like
	** 'if (! (TIME_T_MIN <= *tp + j && *tp + j <= TIME_T_MAX)) ...',
	** except that it does the right thing even if *tp + j would overflow.
	*/
	if (! (j < 0
	       ? (TYPE_SIGNED(time_t) ? TIME_T_MIN - j <= *tp : -1 - j < *tp)
	       : *tp <= TIME_T_MAX - j))
		return true;
	*tp += j;
	return false;
}

static bool
normalize_overflow(int *const tensptr, int *const unitsptr, const int base)
{
	register int	tensdelta;

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

static bool
normalize_overflow32(int_fast32_t *tensptr, int *unitsptr, int base)
{
	register int	tensdelta;

	tensdelta = (*unitsptr >= 0) ?
		(*unitsptr / base) :
		(-1 - (-1 - *unitsptr) / base);
	*unitsptr -= tensdelta * base;
	return increment_overflow32(tensptr, tensdelta);
}

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

	if (atmp->tm_year != btmp->tm_year)
		return atmp->tm_year < btmp->tm_year ? -1 : 1;
	if ((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
time2sub(struct tm *const tmp,
	 struct tm *(*funcp)(struct state const *, time_t const *,
			     int_fast32_t, struct tm *),
	 struct state const *sp,
	 const int_fast32_t offset,
	 bool *okayp,
	 bool do_norm_secs)
{
	register int			dir;
	register int			i, j;
	register int			saved_seconds;
	register int_fast32_t		li;
	register time_t			lo;
	register time_t			hi;
	int_fast32_t			y;
	time_t				newt;
	time_t				t;
	struct tm			yourtm, mytm;

	*okayp = false;
	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_overflow32(&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_overflow32(&y, TM_YEAR_BASE))
		return WRONG;
	while (yourtm.tm_mday <= 0) {
		if (increment_overflow32(&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_overflow32(&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_overflow32(&y, 1))
				return WRONG;
		}
	}
	if (increment_overflow32(&y, -TM_YEAR_BASE))
		return WRONG;
	if (! (INT_MIN <= y && y <= INT_MAX))
		return WRONG;
	yourtm.tm_year = y;
	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).
	*/
	lo = TIME_T_MIN;
	hi = TIME_T_MAX;
	for ( ; ; ) {
		t = lo / 2 + hi / 2;
		if (t < lo)
			t = lo;
		else if (t > hi)
			t = hi;
		if (! funcp(sp, &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) {
				if (t == TIME_T_MAX)
					return WRONG;
				++t;
				++lo;
			} else if (t == hi) {
				if (t == TIME_T_MIN)
					return WRONG;
				--t;
				--hi;
			}
			if (lo > hi)
				return WRONG;
			if (dir > 0)
				hi = t;
			else	lo = t;
			continue;
		}
#if defined TM_GMTOFF && ! UNINIT_TRAP
		if (mytm.TM_GMTOFF != yourtm.TM_GMTOFF
		    && (yourtm.TM_GMTOFF < 0
			? (-SECSPERDAY <= yourtm.TM_GMTOFF
			   && (mytm.TM_GMTOFF <=
			       (SMALLEST (INT_FAST32_MAX, LONG_MAX)
				+ yourtm.TM_GMTOFF)))
			: (yourtm.TM_GMTOFF <= SECSPERDAY
			   && ((BIGGEST (INT_FAST32_MIN, LONG_MIN)
				+ yourtm.TM_GMTOFF)
			       <= mytm.TM_GMTOFF)))) {
		  /* MYTM matches YOURTM except with the wrong UTC offset.
		     YOURTM.TM_GMTOFF is plausible, so try it instead.
		     It's OK if YOURTM.TM_GMTOFF contains uninitialized data,
		     since the guess gets checked.  */
		  time_t altt = t;
		  int_fast32_t diff = mytm.TM_GMTOFF - yourtm.TM_GMTOFF;
		  if (!increment_overflow_time(&altt, diff)) {
		    struct tm alttm;
		    if (funcp(sp, &altt, offset, &alttm)
			&& alttm.tm_isdst == mytm.tm_isdst
			&& alttm.TM_GMTOFF == yourtm.TM_GMTOFF
			&& tmcomp(&alttm, &yourtm) == 0) {
		      t = altt;
		      mytm = alttm;
		    }
		  }
		}
#endif
		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.
		*/
		if (sp == NULL)
			return WRONG;
		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(sp, &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(sp, &t, offset, tmp))
		*okayp = true;
	return t;
}

static time_t
time2(struct tm * const	tmp,
      struct tm *(*funcp)(struct state const *, time_t const *,
			  int_fast32_t, struct tm *),
      struct state const *sp,
      const int_fast32_t offset,
      bool *okayp)
{
	time_t	t;

	/*
	** 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.
	*/
	t = time2sub(tmp, funcp, sp, offset, okayp, false);
	return *okayp ? t : time2sub(tmp, funcp, sp, offset, okayp, true);
}

static time_t
time1(struct tm *const tmp,
      struct tm *(*funcp) (struct state const *, time_t const *,
			   int_fast32_t, struct tm *),
      struct state const *sp,
      const int_fast32_t offset)
{
	register time_t			t;
	register int			samei, otheri;
	register int			sameind, otherind;
	register int			i;
	register int			nseen;
	char				seen[TZ_MAX_TYPES];
	unsigned char			types[TZ_MAX_TYPES];
	bool				okay;

	if (tmp == NULL) {
		errno = EINVAL;
		return WRONG;
	}
	if (tmp->tm_isdst > 1)
		tmp->tm_isdst = 1;
	t = time2(tmp, funcp, sp, offset, &okay);
	if (okay)
		return t;
	if (tmp->tm_isdst < 0)
#ifdef PCTS
		/*
		** POSIX Conformance Test Suite code courtesy Grant Sullivan.
		*/
		tmp->tm_isdst = 0;	/* reset to std and try again */
#else
		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.
	*/
	if (sp == NULL)
		return WRONG;
	for (i = 0; i < sp->typecnt; ++i)
		seen[i] = false;
	nseen = 0;
	for (i = sp->timecnt - 1; i >= 0; --i)
		if (!seen[sp->types[i]]) {
			seen[sp->types[i]] = true;
			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, sp, 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;
}

static time_t
mktime_tzname(struct state *sp, struct tm *tmp, bool setname)
{
  if (sp)
    return time1(tmp, localsub, sp, setname);
  else {
    gmtcheck();
    return time1(tmp, gmtsub, gmtptr, 0);
  }
}

#if NETBSD_INSPIRED

time_t
mktime_z(struct state *sp, struct tm *tmp)
{
  return mktime_tzname(sp, tmp, false);
}

#endif

time_t
mktime(struct tm *tmp)
{
  time_t t;
  int err = lock();
  if (err) {
    errno = err;
    return -1;
  }
  tzset_unlocked();
  t = mktime_tzname(lclptr, tmp, true);
  unlock();
  return t;
}

#ifdef STD_INSPIRED

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

time_t
timegm(struct tm *tmp)
{
  return timeoff(tmp, 0);
}

time_t
timeoff(struct tm *tmp, long offset)
{
  if (tmp)
    tmp->tm_isdst = 0;
  gmtcheck();
  return time1(tmp, gmtsub, gmtptr, offset);
}

#endif /* defined STD_INSPIRED */

/*
** XXX--is the below the right way to conditionalize??
*/

#ifdef STD_INSPIRED

/*
** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
** shall correspond to "Wed Dec 31 23:59:59 UTC 1986", which
** is not the case if we are accounting for leap seconds.
** So, we provide the following conversion routines for use
** when exchanging timestamps with POSIX conforming systems.
*/

static int_fast64_t
leapcorr(struct state const *sp, time_t t)
{
	register struct lsinfo const *	lp;
	register int			i;

	i = sp->leapcnt;
	while (--i >= 0) {
		lp = &sp->lsis[i];
		if (t >= lp->ls_trans)
			return lp->ls_corr;
	}
	return 0;
}

NETBSD_INSPIRED_EXTERN time_t
time2posix_z(struct state *sp, time_t t)
{
  return t - leapcorr(sp, t);
}

time_t
time2posix(time_t t)
{
  int err = lock();
  if (err) {
    errno = err;
    return -1;
  }
  if (!lcl_is_set)
    tzset_unlocked();
  if (lclptr)
    t = time2posix_z(lclptr, t);
  unlock();
  return t;
}

NETBSD_INSPIRED_EXTERN time_t
posix2time_z(struct state *sp, time_t t)
{
	time_t	x;
	time_t	y;
	/*
	** For a positive leap second hit, the result
	** is not unique. For a negative leap second
	** hit, the corresponding time doesn't exist,
	** so we return an adjacent second.
	*/
	x = t + leapcorr(sp, t);
	y = x - leapcorr(sp, x);
	if (y < t) {
		do {
			x++;
			y = x - leapcorr(sp, x);
		} while (y < t);
		x -= y != t;
	} else if (y > t) {
		do {
			--x;
			y = x - leapcorr(sp, x);
		} while (y > t);
		x += y != t;
	}
	return x;
}

time_t
posix2time(time_t t)
{
  int err = lock();
  if (err) {
    errno = err;
    return -1;
  }
  if (!lcl_is_set)
    tzset_unlocked();
  if (lclptr)
    t = posix2time_z(lclptr, t);
  unlock();
  return t;
}

#endif /* defined STD_INSPIRED */

#if TZ_TIME_T

# if !USG_COMPAT
#  define daylight 0
#  define timezone 0
# endif
# ifndef ALTZONE
#  define altzone 0
# endif

/* Convert from the underlying system's time_t to the ersatz time_tz,
   which is called 'time_t' in this file.  Typically, this merely
   converts the time's integer width.  On some platforms, the system
   time is local time not UT, or uses some epoch other than the POSIX
   epoch.

   Although this code appears to define a function named 'time' that
   returns time_t, the macros in private.h cause this code to actually
   define a function named 'tz_time' that returns tz_time_t.  The call
   to sys_time invokes the underlying system's 'time' function.  */

time_t
time(time_t *p)
{
  time_t r = sys_time(0);
  if (r != (time_t) -1) {
    int_fast32_t offset = EPOCH_LOCAL ? (daylight ? timezone : altzone) : 0;
    if (increment_overflow32(&offset, -EPOCH_OFFSET)
	|| increment_overflow_time (&r, offset)) {
      errno = EOVERFLOW;
      r = -1;
    }
  }
  if (p)
    *p = r;
  return r;
}

#endif