Initial Contribution

1 files changed, 1915 insertions, 0 deletions

diff --git a/libcutils/tztime.c b/libcutils/tztime.c
new file mode 100644
index 0000000..93bbb29
--- /dev/null
+++ b/libcutils/tztime.c
@@ -0,0 +1,1915 @@
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+#include <stdio.h>
+
+#ifndef lint
+#ifndef NOID
+static char	elsieid[] = "@(#)localtime.c	8.3";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*
+** Leap second handling from Bradley White.
+** POSIX-style TZ environment variable handling from Guy Harris.
+*/
+
+/*LINTLIBRARY*/
+
+#include "private.h"
+#include "tzfile.h"
+#include "fcntl.h"
+#include "float.h"	/* for FLT_MAX and DBL_MAX */
+
+#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 INDEXFILE "/system/usr/share/zoneinfo/zoneinfo.idx"
+#define DATAFILE "/system/usr/share/zoneinfo/zoneinfo.dat"
+#define NAMELEN 40
+#define INTLEN 4
+#define READLEN (NAMELEN + 3 * INTLEN)
+
+/*
+** 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 char		wildabbr[] = WILDABBR;
+
+static const char	gmt[] = "GMT";
+
+/*
+** 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 /* !defined TZDEFDST */
+
+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 */
+
+/*
+** Prototypes for static functions.
+*/
+
+static long		detzcode P((const char * codep));
+static time_t		detzcode64 P((const char * codep));
+static int		differ_by_repeat P((time_t t1, time_t t0));
+static const char *	getzname P((const char * strp));
+static const char *	getqzname P((const char * strp, const int delim));
+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 struct tm *	gmtsub P((const time_t * timep, long offset,
+				struct tm * tmp));
+static struct tm *	localsub P((const time_t * timep, long offset,
+				struct tm * tmp, struct state *sp));
+static int		increment_overflow P((int * number, int delta));
+static int		leaps_thru_end_of P((int y));
+static int		long_increment_overflow P((long * number, int delta));
+static int		long_normalize_overflow P((long * tensptr,
+				int * unitsptr, int base));
+static int		normalize_overflow P((int * tensptr, int * unitsptr,
+				int base));
+static void		settzname P((void));
+static time_t		time1 P((struct tm * tmp,
+				struct tm * (*funcp) P((const time_t *,
+				long, struct tm *, const struct state* sp)),
+				long offset, const struct state *	sp));
+static time_t		time2 P((struct tm *tmp,
+				struct tm * (*funcp) P((const time_t *,
+				long, struct tm*, const struct state* sp)),
+				long offset, int * okayp, const struct state *	sp));
+static time_t		time2sub P((struct tm *tmp,
+				struct tm * (*funcp) P((const time_t*, long, struct tm*,const struct state *sp)),
+				long offset, int * okayp, int do_norm_secs,
+                const struct state *sp));
+static struct tm *	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,
+				int doextend));
+static int		tzload_uncached P((const char * name, struct state * sp,
+				int doextend));
+static int		tzparse P((const char * name, struct state * sp,
+				int lastditch));
+
+#ifdef ALL_STATE
+static struct state *	gmtptr;
+#endif /* defined ALL_STATE */
+
+#ifndef ALL_STATE
+static struct state	gmtmem;
+#define gmtptr		(&gmtmem)
+#endif /* State Farm */
+
+#define CACHE_COUNT 4
+static char * g_cacheNames[CACHE_COUNT] = {0,0};
+static struct state	g_cacheStates[CACHE_COUNT];
+static int g_lastCache = 0;
+static struct state g_utc;
+unsigned char g_utcSet = 0;
+
+
+#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;
+static int		gmt_is_set;
+
+char *			tzname[2] = {
+	wildabbr,
+	wildabbr
+};
+
+/*
+** 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;
+
+#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 = (codep[0] & 0x80) ? ~0L : 0;
+	for (i = 0; i < 4; ++i)
+		result = (result << 8) | (codep[i] & 0xff);
+	return result;
+}
+
+static time_t
+detzcode64(codep)
+const char * const	codep;
+{
+	register time_t	result;
+	register 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;
+}
+
+static int
+differ_by_repeat(t1, t0)
+const time_t	t1;
+const time_t	t0;
+{
+	if (TYPE_INTEGRAL(time_t) &&
+		TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
+			return 0;
+	return t1 - t0 == SECSPERREPEAT;
+}
+
+static int toint(unsigned char *s) {
+    return (s[0] << 24) | (s[1] << 16) | (s[2] << 8) | s[3];
+}
+
+static int
+tzload(const char *name, struct state * const sp, const int doextend)
+{
+    if (name) {
+        int i, err;
+        if (0 == strcmp(name, "UTC")) {
+            if (!g_utcSet) {
+                tzload_uncached(name, &g_utc, 1);
+                g_utcSet = 1;
+            }
+            //printf("tzload: utc\n");
+            *sp = g_utc;
+            return 0;
+        }
+        for (i=0; i<CACHE_COUNT; i++) {
+            if (g_cacheNames[i] && 0 == strcmp(name, g_cacheNames[i])) {
+                *sp = g_cacheStates[i];
+                //printf("tzload: hit: %s\n", name);
+                return 0;
+            }
+        }
+        //printf("tzload: miss: %s\n", name);
+        g_lastCache++;
+        if (g_lastCache >= CACHE_COUNT) {
+            g_lastCache = 0;
+        }
+        i = g_lastCache;
+        if (g_cacheNames[i]) {
+            free(g_cacheNames[i]);
+        }
+        err = tzload_uncached(name, &(g_cacheStates[i]), 1);
+        if (err == 0) {
+            g_cacheNames[i] = strdup(name);
+            *sp = g_cacheStates[i];
+            return 0;
+        } else {
+            g_cacheNames[i] = NULL;
+            return err;
+        }
+    }
+    return tzload_uncached(name, sp, doextend);
+}
+
+static int
+tzload_uncached(name, sp, doextend)
+register const char *		name;
+register struct state * const	sp;
+register const int		doextend;
+{
+	register const char *		p;
+	register int			i;
+	register int			fid;
+	register int			stored;
+	register int			nread;
+	union {
+		struct tzhead	tzhead;
+		char		buf[2 * sizeof(struct tzhead) +
+					2 * sizeof *sp +
+					4 * TZ_MAX_TIMES];
+	} u;
+    int                     toread = sizeof u.buf;
+
+	if (name == NULL && (name = TZDEFAULT) == NULL)
+		return -1;
+	{
+		register int	doaccess;
+		/*
+		** 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[FILENAME_MAX + 1];
+		const char	*origname = name;
+
+		if (name[0] == ':')
+			++name;
+		doaccess = name[0] == '/';
+		if (!doaccess) {
+			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);
+			/*
+			** Set doaccess if '.' (as in "../") shows up in name.
+			*/
+			if (strchr(name, '.') != NULL)
+				doaccess = TRUE;
+			name = fullname;
+		}
+		if (doaccess && access(name, R_OK) != 0)
+			return -1;
+		if ((fid = open(name, OPEN_MODE)) == -1) {
+            char buf[READLEN];
+            char name[NAMELEN + 1];
+            int fidix = open(INDEXFILE, OPEN_MODE);
+            int off = -1;
+
+            if (fidix < 0) {
+                return -1;
+            }
+
+            while (read(fidix, buf, sizeof(buf)) == sizeof(buf)) {
+                memcpy(name, buf, NAMELEN);
+                name[NAMELEN] = '\0';
+
+                if (strcmp(name, origname) == 0) {
+                    off = toint((unsigned char *) buf + NAMELEN);
+                    toread = toint((unsigned char *) buf + NAMELEN + INTLEN);
+                    break;
+                }
+            }
+
+            close(fidix);
+
+            if (off < 0)
+                return -1;
+
+            fid = open(DATAFILE, OPEN_MODE);
+
+            if (fid < 0) {
+                return -1;
+            }
+
+            if (lseek(fid, off, SEEK_SET) < 0) {
+                return -1;
+            }
+        }
+	}
+	nread = read(fid, u.buf, toread);
+	if (close(fid) < 0 || nread <= 0)
+		return -1;
+	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))
+				return -1;
+		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 */
+				return -1;
+		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)
+				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 = (stored == 4) ?
+				detzcode(p) : detzcode64(p);
+			p += stored;
+			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;
+			}
+		}
+		for (i = 0; i < sp->typecnt; ++i) {
+			register struct ttinfo *	ttisp;
+
+			ttisp = &sp->ttis[i];
+			if (ttisgmtcnt == 0)
+				ttisp->tt_ttisgmt = FALSE;
+			else {
+				ttisp->tt_ttisgmt = *p++;
+				if (ttisp->tt_ttisgmt != TRUE &&
+					ttisp->tt_ttisgmt != FALSE)
+						return -1;
+			}
+		}
+		/*
+		** 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;
+
+			u.buf[nread - 1] = '\0';
+			result = tzparse(&u.buf[1], &ts, FALSE);
+			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];
+			}
+	}
+	i = 2 * YEARSPERREPEAT;
+	sp->goback = sp->goahead = sp->timecnt > i;
+	sp->goback &= sp->types[i] == sp->types[0] &&
+		differ_by_repeat(sp->ats[i], sp->ats[0]);
+	sp->goahead &=
+		sp->types[sp->timecnt - 1] == sp->types[sp->timecnt - 1 - i] &&
+		differ_by_repeat(sp->ats[sp->timecnt - 1],
+			 sp->ats[sp->timecnt - 1 - i]);
+	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' && !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(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 || !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(strp, secsp)
+register const char *	strp;
+long * 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(strp, offsetp)
+register const char *	strp;
+long * const		offsetp;
+{
+	register 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(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 (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;
+}
+
+/*
+** 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(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;
+
+	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 = 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 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(name, sp, lastditch)
+const char *			name;
+register struct state * const	sp;
+const int			lastditch;
+{
+	const char *			stdname;
+	const char *			dstname;
+	size_t				stdlen;
+	size_t				dstlen;
+	long				stdoffset;
+	long				dstoffset;
+	register time_t *		atp;
+	register unsigned char *	typep;
+	register char *			cp;
+	register int			load_result;
+
+	INITIALIZE(dstname);
+	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;
+		name = getoffset(name, &stdoffset);
+		if (name == NULL)
+			return -1;
+	}
+	load_result = tzload(TZDEFRULES, sp, FALSE);
+	if (load_result != 0)
+		sp->leapcnt = 0;		/* so, we're off a little */
+	sp->timecnt = 0;
+	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;
+			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 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;
+			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 {
+			register long	theirstdoffset;
+			register long	theirdstoffset;
+			register long	theiroffset;
+			register int	isdst;
+			register int	i;
+			register 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 = 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.
+			** ttisstd and ttisgmt need not be handled.
+			*/
+			sp->ttis[0].tt_gmtoff = -stdoffset;
+			sp->ttis[0].tt_isdst = FALSE;
+			sp->ttis[0].tt_abbrind = 0;
+			sp->ttis[1].tt_gmtoff = -dstoffset;
+			sp->ttis[1].tt_isdst = TRUE;
+			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 void
+gmtload(sp)
+struct state * const	sp;
+{
+	if (tzload(gmt, sp, TRUE) != 0)
+		(void) tzparse(gmt, sp, TRUE);
+}
+
+/*
+** 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(timep, offset, tmp, sp)
+const time_t * const	timep;
+const long		offset;
+struct tm * const	tmp;
+struct state *		sp;
+{
+	register const struct ttinfo *	ttisp;
+	register int			i;
+	register struct tm *		result;
+	const time_t			t = *timep;
+
+#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, sp);
+			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;
+#ifdef HAVE_TM_GMTOFF
+	tmp->tm_gmtoff = ttisp->tt_gmtoff;
+#endif
+	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
+#ifdef TM_ZONE
+	tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
+#endif /* defined TM_ZONE */
+	return result;
+}
+
+
+// ============================================================================
+#if 0
+struct tm *
+localtime(timep)
+const time_t * const	timep;
+{
+	tzset();
+	return localsub(timep, 0L, &tm);
+}
+#endif
+
+/*
+** Re-entrant version of localtime.
+*/
+
+// ============================================================================
+void
+localtime_tz(const time_t * const timep, struct tm * tmp, const char* tz)
+{
+    struct state st;
+    if (tzload(tz, &st, TRUE) != 0) {
+        // not sure what's best here, but for now, we fall back to gmt
+        gmtload(&st);
+    }
+
+	localsub(timep, 0L, tmp, &st);
+}
+
+/*
+** gmtsub is to gmtime as localsub is to localtime.
+*/
+
+static struct tm *
+gmtsub(timep, offset, tmp)
+const time_t * const	timep;
+const long		offset;
+struct tm * const	tmp;
+{
+	register struct tm *	result;
+
+	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);
+	}
+	result = timesub(timep, offset, gmtptr, tmp);
+#ifdef TM_ZONE
+	/*
+	** Could get fancy here and deliver something such as
+	** "UTC+xxxx" or "UTC-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 */
+	}
+#endif /* defined TM_ZONE */
+	return result;
+}
+
+// ============================================================================
+#if 0
+struct tm *
+gmtime(timep)
+const time_t * const	timep;
+{
+	return gmtsub(timep, 0L, &tm);
+}
+#endif
+
+/*
+* Re-entrant version of gmtime.
+*/
+
+// ============================================================================
+#if 0
+struct tm *
+gmtime_r(timep, tmp)
+const time_t * const	timep;
+struct tm *		tmp;
+{
+	return gmtsub(timep, 0L, tmp);
+}
+#endif
+
+#ifdef STD_INSPIRED
+
+// ============================================================================
+#if 0
+struct tm *
+offtime(timep, offset)
+const time_t * const	timep;
+const long		offset;
+{
+	return gmtsub(timep, offset, &tm);
+}
+#endif
+
+#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(y)
+register const int	y;
+{
+	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
+		-(leaps_thru_end_of(-(y + 1)) + 1);
+}
+
+static struct tm *
+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 time_t			tdays;
+	register int			idays;	/* unsigned would be so 2003 */
+	register long			rem;
+	int				y;
+	register const int *		ip;
+	register long			corr;
+	register int			hit;
+	register int			i;
+
+	corr = 0;
+	hit = 0;
+#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);
+				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;
+#ifdef TM_GMTOFF
+	tmp->TM_GMTOFF = offset;
+#endif /* defined TM_GMTOFF */
+	return tmp;
+}
+
+// ============================================================================
+#if 0
+char *
+ctime(timep)
+const time_t * const	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))
+*/
+	return asctime(localtime(timep));
+}
+#endif
+
+// ============================================================================
+#if 0
+char *
+ctime_r(timep, buf)
+const time_t * const	timep;
+char *			buf;
+{
+	struct tm	mytm;
+
+	return asctime_r(localtime_r(timep, &mytm), buf);
+}
+#endif
+
+/*
+** 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 */
+
+/*
+** Simplified normalize logic courtesy Paul Eggert.
+*/
+
+static int
+increment_overflow(number, delta)
+int *	number;
+int	delta;
+{
+	int	number0;
+
+	number0 = *number;
+	*number += delta;
+	return (*number < number0) != (delta < 0);
+}
+
+static int
+long_increment_overflow(number, delta)
+long *	number;
+int	delta;
+{
+	long	number0;
+
+	number0 = *number;
+	*number += delta;
+	return (*number < number0) != (delta < 0);
+}
+
+static int
+normalize_overflow(tensptr, unitsptr, base)
+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 int
+long_normalize_overflow(tensptr, unitsptr, base)
+long * const	tensptr;
+int * const	unitsptr;
+const int	base;
+{
+	register int	tensdelta;
+
+	tensdelta = (*unitsptr >= 0) ?
+		(*unitsptr / base) :
+		(-1 - (-1 - *unitsptr) / base);
+	*unitsptr -= tensdelta * base;
+	return long_increment_overflow(tensptr, tensdelta);
+}
+
+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
+time2sub(tmp, funcp, offset, okayp, do_norm_secs, sp)
+struct tm * const	tmp;
+struct tm * (* const	funcp) P((const time_t*, long, struct tm*,const struct state *sp));
+const long		offset;
+int * const		okayp;
+const int		do_norm_secs;
+const struct state *	sp;
+{
+	register int			dir;
+	register int			i, j;
+	register int			saved_seconds;
+	register long			li;
+	register time_t			lo;
+	register time_t			hi;
+	long				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 (long_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 (long_increment_overflow(&y, TM_YEAR_BASE))
+		return WRONG;
+	while (yourtm.tm_mday <= 0) {
+		if (long_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 (long_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 (long_increment_overflow(&y, 1))
+				return WRONG;
+		}
+	}
+	if (long_increment_overflow(&y, -TM_YEAR_BASE))
+		return WRONG;
+	yourtm.tm_year = y;
+	if (yourtm.tm_year != y)
+		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, sp) == NULL) {
+			/*
+			** 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.
+		*/
+		/*
+		** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
+		*/
+#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, sp) == NULL)
+					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, sp))
+		*okayp = TRUE;
+	return t;
+}
+
+static time_t
+time2(tmp, funcp, offset, okayp, sp)
+struct tm * const	tmp;
+struct tm * (* const	funcp) P((const time_t*, long, struct tm*,
+            const struct state* sp));
+const long		offset;
+int * const		okayp;
+const struct state *	sp;
+{
+	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, offset, okayp, FALSE, sp);
+	return *okayp ? t : time2sub(tmp, funcp, offset, okayp, TRUE, sp);
+}
+
+static time_t
+time1(tmp, funcp, offset, sp)
+struct tm * const	tmp;
+struct tm * (* const	funcp) P((const time_t *, long, struct tm *, const struct state* sp));
+const long		offset;
+const struct state *	sp;
+{
+	register time_t			t;
+	register int			samei, otheri;
+	register int			sameind, otherind;
+	register int			i;
+	register int			nseen;
+	int				seen[TZ_MAX_TYPES];
+	int				types[TZ_MAX_TYPES];
+	int				okay;
+
+	if (tmp->tm_isdst > 1)
+		tmp->tm_isdst = 1;
+	t = time2(tmp, funcp, offset, &okay, sp);
+#define PCTS 1
+#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 */
+#endif /* defined PCTS */
+#ifndef PCTS
+	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.
+	*/
+	/*
+	** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
+	*/
+#ifdef ALL_STATE
+	if (sp == NULL)
+		return WRONG;
+#endif /* defined ALL_STATE */
+	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, offset, &okay, sp);
+			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_tz(struct tm * const	tmp, char const * tz)
+{
+    struct state st;
+    if (tzload(tz, &st, TRUE) != 0) {
+        // not sure what's best here, but for now, we fall back to gmt
+        gmtload(&st);
+    }
+	return time1(tmp, localsub, 0L, &st);
+}