Import most recent NetBSD localtime.c, private.h, and tzfile.h.  An
empty namespace.h suffices for Cygwin.

---
 winsup/cygwin/tzcode/localtime.c | 2493 ++++++++++++++++++++++++++++++
 winsup/cygwin/tzcode/namespace.h |    0
 winsup/cygwin/tzcode/private.h   |  795 ++++++++++
 winsup/cygwin/tzcode/tzfile.h    |  174 +++
 4 files changed, 3462 insertions(+)
 create mode 100644 winsup/cygwin/tzcode/localtime.c
 create mode 100644 winsup/cygwin/tzcode/namespace.h
 create mode 100644 winsup/cygwin/tzcode/private.h
 create mode 100644 winsup/cygwin/tzcode/tzfile.h

diff --git a/winsup/cygwin/tzcode/localtime.c b/winsup/cygwin/tzcode/localtime.c
new file mode 100644
index 000000000..a4d02a4c7
--- /dev/null
+++ b/winsup/cygwin/tzcode/localtime.c
@@ -0,0 +1,2493 @@
+/*     $NetBSD: localtime.c,v 1.122 2019/07/03 15:50:16 christos Exp $ */
+
+/* Convert timestamp from time_t to struct tm.  */
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+#if 0
+static char    elsieid[] = "@(#)localtime.c    8.17";
+#else
+__RCSID("$NetBSD: localtime.c,v 1.122 2019/07/03 15:50:16 christos Exp $");
+#endif
+#endif /* LIBC_SCCS and not lint */
+
+/*
+** Leap second handling from Bradley White.
+** POSIX-style TZ environment variable handling from Guy Harris.
+*/
+
+/*LINTLIBRARY*/
+
+#include "namespace.h"
+#include <assert.h>
+#define LOCALTIME_IMPLEMENTATION
+#include "private.h"
+
+#include "tzfile.h"
+#include <fcntl.h>
+
+#if NETBSD_INSPIRED
+# define NETBSD_INSPIRED_EXTERN
+#else
+# define NETBSD_INSPIRED_EXTERN static
+#endif
+
+#if defined(__weak_alias)
+__weak_alias(daylight,_daylight)
+__weak_alias(tzname,_tzname)
+#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 | O_CLOEXEC)
+#endif /* defined O_BINARY */
+#ifndef O_BINARY
+#define OPEN_MODE      (O_RDONLY | O_CLOEXEC)
+#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 does not specify the default DST rules;
+** 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_utoff;       /* UT offset in seconds */
+       bool            tt_isdst;       /* used to set tm_isdst */
+       int             tt_desigidx;    /* abbreviation list index */
+       bool            tt_ttisstd;     /* transition is std time */
+       bool            tt_ttisut;      /* 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 */
+
+#define state __state
+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[/*CONSTCOND*/BIGGEST(BIGGEST(TZ_MAX_CHARS + 1,
+                               sizeof gmt), (2 * (MY_TZNAME_MAX + 1)))];
+       struct lsinfo   lsis[TZ_MAX_LEAPS];
+
+       /* The time type to use for early times or if no transitions.
+          It is always zero for recent tzdb releases.
+          It might be nonzero for data from tzdb 2018e or earlier.  */
+       int defaulttype;
+};
+
+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);
+
+static timezone_t gmtptr;
+
+#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;
+
+
+#if !defined(__LIBC12_SOURCE__)
+timezone_t __lclptr;
+#ifdef _REENTRANT
+rwlock_t __lcl_lock = RWLOCK_INITIALIZER;
+#endif
+#endif
+
+/*
+** 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 || defined(__NetBSD__)
+# if !defined(__LIBC12_SOURCE__)
+
+__aconst char *                tzname[2] = {
+       (__aconst char *)__UNCONST(wildabbr),
+       (__aconst char *)__UNCONST(wildabbr)
+};
+
+# else
+
+extern __aconst char * tzname[2];
+
+# endif /* __LIBC12_SOURCE__ */
+
+# if USG_COMPAT
+#  if !defined(__LIBC12_SOURCE__)
+long                   timezone = 0;
+int                    daylight = 0;
+#  else
+extern int             daylight;
+extern long            timezone __RENAME(__timezone13);
+#  endif /* __LIBC12_SOURCE__ */
+# endif /* defined USG_COMPAT */
+
+# ifdef ALTZONE
+long                   altzone = 0;
+# endif /* defined ALTZONE */
+#endif /* !HAVE_POSIX_DECLS */
+
+/* Initialize *S to a value based on UTOFF, ISDST, and DESIGIDX.  */
+static void
+init_ttinfo(struct ttinfo *s, int_fast32_t utoff, bool isdst, int desigidx)
+{
+       s->tt_utoff = utoff;
+       s->tt_isdst = isdst;
+       s->tt_desigidx = desigidx;
+       s->tt_ttisstd = false;
+       s->tt_ttisut = false;
+}
+
+static int_fast32_t
+detzcode(const char *const codep)
+{
+       int_fast32_t result;
+       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)
+{
+       int_fast64_t result;
+       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;
+}
+
+#include <stdio.h>
+
+const char *
+tzgetname(const timezone_t sp, int isdst)
+{
+       int i;
+       const char *name = NULL;
+       for (i = 0; i < sp->typecnt; ++i) {
+               const struct ttinfo *const ttisp = &sp->ttis[i];
+               if (ttisp->tt_isdst == isdst)
+                       name = &sp->chars[ttisp->tt_desigidx];
+       }
+       if (name != NULL)
+               return name;
+       errno = ESRCH;
+       return NULL;
+}
+
+long
+tzgetgmtoff(const timezone_t sp, int isdst)
+{
+       int i;
+       long l = -1;
+       for (i = 0; i < sp->typecnt; ++i) {
+               const struct ttinfo *const ttisp = &sp->ttis[i];
+
+               if (ttisp->tt_isdst == isdst) {
+                       l = ttisp->tt_utoff;
+               }
+       }
+       if (l == -1)
+               errno = ESRCH;
+       return l;
+}
+
+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) {
+               const struct ttinfo * const     ttisp = &sp->ttis[i];
+               char *cp = &sp->chars[ttisp->tt_desigidx];
+
+               if (strlen(cp) > TZ_ABBR_MAX_LEN &&
+                       strcmp(cp, GRANDPARENTED) != 0)
+                               *(cp + TZ_ABBR_MAX_LEN) = '\0';
+       }
+}
+
+static void
+update_tzname_etc(const struct state *sp, const struct ttinfo *ttisp)
+{
+#if HAVE_TZNAME
+       tzname[ttisp->tt_isdst] = __UNCONST(&sp->chars[ttisp->tt_desigidx]);
+#endif
+#if USG_COMPAT
+       if (!ttisp->tt_isdst)
+               timezone = - ttisp->tt_utoff;
+#endif
+#ifdef ALTZONE
+       if (ttisp->tt_isdst)
+           altzone = - ttisp->tt_utoff;
+#endif /* defined ALTZONE */
+}
+
+static void
+settzname(void)
+{
+       timezone_t const        sp = __lclptr;
+       int                     i;
+
+#if HAVE_TZNAME
+       tzname[0] = tzname[1] =
+           (__aconst char *) __UNCONST(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 time zone abbreviations into tzname. . .
+       */
+       for (i = 0; i < sp->typecnt; ++i)
+               update_tzname_etc(sp, &sp->ttis[i]);
+
+       for (i = 0; i < sp->timecnt; ++i) {
+               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 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 (int_fast64_t)t1 - (int_fast64_t)t0 == SECSPERREPEAT;
+}
+
+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[/*CONSTCOND*/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)
+{
+       int                     i;
+       int                     fid;
+       int                     stored;
+       ssize_t                 nread;
+       bool                    doaccess;
+       union input_buffer      *up = &lsp->u.u;
+       size_t                  tzheadsize = sizeof(struct tzhead);
+
+       sp->goback = sp->goahead = false;
+
+       if (! name) {
+               name = TZDEFAULT;
+               if (! name)
+                       return EINVAL;
+       }
+
+       if (name[0] == ':')
+               ++name;
+#ifdef SUPPRESS_TZDIR
+       /* Do not prepend TZDIR.  This is intended for specialized
+          applications only, due to its security implications.  */
+       doaccess = true;
+#else
+       doaccess = name[0] == '/';
+#endif
+       if (!doaccess) {
+               char const *dot;
+               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 NAME contains a ".." file name
+                  component, as such a name could read a file outside
+                  the TZDIR virtual subtree.  */
+               for (dot = name; (dot = strchr(dot, '.')) != NULL; dot++)
+                 if ((dot == name || dot[-1] == '/') && dot[1] == '.'
+                     && (dot[2] == '/' || !dot[2])) {
+                   doaccess = true;
+                   break;
+                 }
+
+               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 < (ssize_t)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 ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt);
+               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;
+               /* Although tzfile(5) currently requires typecnt to be nonzero,
+                  support future formats that may allow zero typecnt
+                  in files that have a TZ string and no transitions.  */
+               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)
+                      && (ttisutcnt == typecnt || ttisutcnt == 0)))
+                 return EINVAL;
+               if ((size_t)nread
+                   < (tzheadsize               /* struct tzhead */
+                      + timecnt * stored       /* ats */
+                      + timecnt                /* types */
+                      + typecnt * 6            /* ttinfos */
+                      + charcnt                /* chars */
+                      + leapcnt * (stored + 4) /* lsinfos */
+                      + ttisstdcnt             /* ttisstds */
+                      + ttisutcnt))            /* ttisuts */
+                 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 : (time_t)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) {
+                       struct ttinfo * ttisp;
+                       unsigned char isdst, desigidx;
+
+                       ttisp = &sp->ttis[i];
+                       ttisp->tt_utoff = detzcode(p);
+                       p += 4;
+                       isdst = *p++;
+                       if (! (isdst < 2))
+                               return EINVAL;
+                       ttisp->tt_isdst = isdst;
+                       desigidx = *p++;
+                       if (! (desigidx < sp->charcnt))
+                               return EINVAL;
+                       ttisp->tt_desigidx = desigidx;
+               }
+               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 =
+                                   (time_t)(prevtr = tr);
+                               sp->lsis[leapcnt].ls_corr = prevcorr = corr;
+                               leapcnt++;
+                       }
+               }
+               sp->leapcnt = leapcnt;
+
+               for (i = 0; i < sp->typecnt; ++i) {
+                       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) {
+                       struct ttinfo * ttisp;
+
+                       ttisp = &sp->ttis[i];
+                       if (ttisutcnt == 0)
+                               ttisp->tt_ttisut = false;
+                       else {
+                               if (*p != true && *p != false)
+                                               return EINVAL;
+                               ttisp->tt_ttisut = *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, (size_t)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)) {
+
+                         /* 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 < ts->typecnt; i++) {
+                           char *tsabbr = ts->chars + ts->ttis[i].tt_desigidx;
+                           int j;
+                           for (j = 0; j < charcnt; j++)
+                             if (strcmp(sp->chars + j, tsabbr) == 0) {
+                               ts->ttis[i].tt_desigidx = j;
+                               gotabbr++;
+                               break;
+                             }
+                           if (! (j < charcnt)) {
+                             size_t tsabbrlen = strlen(tsabbr);
+                             if (j + tsabbrlen < TZ_MAX_CHARS) {
+                               strcpy(sp->chars + j, tsabbr);
+                               charcnt = (int_fast32_t)(j + tsabbrlen + 1);
+                               ts->ttis[i].tt_desigidx = j;
+                               gotabbr++;
+                             }
+                           }
+                         }
+                         if (gotabbr == ts->typecnt) {
+                           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->timecnt == 0
+                                 || 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++;
+                           }
+                           for (i = 0; i < ts->typecnt; i++)
+                             sp->ttis[sp->typecnt++] = ts->ttis[i];
+                         }
+                       }
+       }
+       if (sp->typecnt == 0)
+         return EINVAL;
+       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;
+               }
+       }
+
+       /* Infer sp->defaulttype from the data.  Although this default
+          type is always zero for data from recent tzdb releases,
+          things are trickier for data from tzdb 2018e or earlier.
+
+          The first set of heuristics work around bugs in 32-bit data
+          generated by tzdb 2013c or earlier.  The workaround is for
+          zones like Australia/Macquarie where timestamps before the
+          first transition have a time type that is not the earliest
+          standard-time type.  See:
+          https://mm.icann.org/pipermail/tz/2013-May/019368.html */
+       /*
+       ** 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;
+       }
+       /* The next heuristics are for data generated by tzdb 2018e or
+          earlier, for zones like EST5EDT where the first transition
+          is to DST.  */
+       /*
+       ** 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;
+                       }
+       }
+       /* A simple 'sp->defaulttype = 0;' would suffice here if we
+          didn't have to worry about 2018e-or-earlier data.  Even
+          simpler would be to remove the defaulttype member and just
+          use 0 in its place.  */
+       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)
+{
+       union local_storage *lsp = malloc(sizeof *lsp);
+       if (!lsp)
+               return errno;
+       else {
+               int err = tzloadbody(name, sp, doextend, lsp);
+               free(lsp);
+               return err;
+       }
+}
+
+static bool
+typesequiv(const struct state *sp, int a, int b)
+{
+       bool result;
+
+       if (sp == NULL ||
+               a < 0 || a >= sp->typecnt ||
+               b < 0 || b >= sp->typecnt)
+                       result = false;
+       else {
+               const struct ttinfo *   ap = &sp->ttis[a];
+               const struct ttinfo *   bp = &sp->ttis[b];
+               result = (ap->tt_utoff == bp->tt_utoff
+                         && ap->tt_isdst == bp->tt_isdst
+                         && ap->tt_ttisstd == bp->tt_ttisstd
+                         && ap->tt_ttisut == bp->tt_ttisut
+                         && (strcmp(&sp->chars[ap->tt_desigidx],
+                                    &sp->chars[bp->tt_desigidx])
+                             == 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 timezone string, scan until a character that is not
+** a valid character in a time zone abbreviation is found.
+** Return a pointer to that character.
+*/
+
+static ATTRIBUTE_PURE const char *
+getzname(const char *strp)
+{
+       char    c;
+
+       while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
+               c != '+')
+                       ++strp;
+       return strp;
+}
+
+/*
+** Given a pointer into an extended timezone string, scan until the ending
+** delimiter of the time zone abbreviation 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 ATTRIBUTE_PURE const char *
+getqzname(const char *strp, const int delim)
+{
+       int     c;
+
+       while ((c = *strp) != '\0' && c != delim)
+               ++strp;
+       return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract a number from that string.
+** Check that the number is within a specified range; if it is not, return
+** NULL.
+** Otherwise, return a pointer to the first character not part of the number.
+*/
+
+static const char *
+getnum(const char *strp, int *const nump, const int min, const int max)
+{
+       char    c;
+       int     num;
+
+       if (strp == NULL || !is_digit(c = *strp)) {
+               errno = EINVAL;
+               return NULL;
+       }
+       num = 0;
+       do {
+               num = num * 10 + (c - '0');
+               if (num > max) {
+                       errno = EOVERFLOW;
+                       return NULL;    /* illegal value */
+               }
+               c = *++strp;
+       } while (is_digit(c));
+       if (num < min) {
+               errno = EINVAL;
+               return NULL;            /* illegal value */
+       }
+       *nump = num;
+       return strp;
+}
+
+/*
+** Given a pointer into a timezone string, extract a number of seconds,
+** in hh[:mm[:ss]] form, from the string.
+** If any error occurs, return NULL.
+** Otherwise, return a pointer to the first character not part of the number
+** of seconds.
+*/
+
+static const char *
+getsecs(const char *strp, 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 timezone string, extract an offset, in
+** [+-]hh[:mm[:ss]] form, from the string.
+** If any error occurs, return NULL.
+** Otherwise, return a pointer to the first character not part of the time.
+*/
+
+static const char *
+getoffset(const char *strp, int_fast32_t *const offsetp)
+{
+       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 timezone string, extract a rule in the form
+** date[/time]. See POSIX section 8 for the format of "date" and "time".
+** If a valid rule is not found, return NULL.
+** Otherwise, return a pointer to the first character not part of the rule.
+*/
+
+static const char *
+getrule(const char *strp, struct rule *const rulep)
+{
+       if (*strp == 'J') {
+               /*
+               ** Julian day.
+               */
+               rulep->r_type = JULIAN_DAY;
+               ++strp;
+               strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
+       } else if (*strp == 'M') {
+               /*
+               ** Month, week, day.
+               */
+               rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
+               ++strp;
+               strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
+               if (strp == NULL)
+                       return NULL;
+               if (*strp++ != '.')
+                       return NULL;
+               strp = getnum(strp, &rulep->r_week, 1, 5);
+               if (strp == NULL)
+                       return NULL;
+               if (*strp++ != '.')
+                       return NULL;
+               strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
+       } else if (is_digit(*strp)) {
+               /*
+               ** Day of year.
+               */
+               rulep->r_type = DAY_OF_YEAR;
+               strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
+       } else  return NULL;            /* invalid format */
+       if (strp == NULL)
+               return NULL;
+       if (*strp == '/') {
+               /*
+               ** Time specified.
+               */
+               ++strp;
+               strp = 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, const struct rule *const rulep,
+         const int_fast32_t offset)
+{
+       bool    leapyear;
+       int_fast32_t value;
+       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;
+       char *          cp;
+       bool            load_ok;
+
+       dstname = NULL; /* XXX gcc */
+       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 abbr. */
+               }
+               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;
+                       int             year;
+                       int             yearlim;
+                       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], -stdoffset, false, 0);
+                       init_ttinfo(&sp->ttis[1], -dstoffset, true, 
+                           (int)(stdlen + 1));
+                       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;
+                                       sp->ats[timecnt] = janfirst;
+                                       if (! increment_overflow_time
+                                           (&sp->ats[timecnt],
+                                            janoffset + endtime)) {
+                                         sp->types[timecnt++] = reversed;
+                                         yearlim = year + YEARSPERREPEAT + 1;
+                                       }
+                               }
+                               if (increment_overflow_time
+                                   (&janfirst, janoffset + yearsecs))
+                                       break;
+                               janoffset = 0;
+                       }
+                       sp->timecnt = timecnt;
+                       if (! timecnt) {
+                               sp->ttis[0] = sp->ttis[1];
+                               sp->typecnt = 1;        /* Perpetual DST.  */
+                       } else if (YEARSPERREPEAT < year - yearbeg)
+                               sp->goback = sp->goahead = true;
+               } else {
+                       int_fast32_t    theirstdoffset;
+                       int_fast32_t    theirdstoffset;
+                       int_fast32_t    theiroffset;
+                       bool            isdst;
+                       int             i;
+                       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_utoff;
+                                       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_utoff;
+                                       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_ttisut) {
+                                       /* No adjustment to transition time */
+                               } else {
+                                       /*
+                                       ** If daylight saving time is in
+                                       ** effect, and the transition time was
+                                       ** not specified as standard time, add
+                                       ** the daylight saving 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] += (time_t)
+                                                   (dstoffset - 
theirdstoffset);
+                                       } else {
+                                               sp->ats[i] += (time_t)
+                                                   (stdoffset - 
theirstdoffset);
+                                       }
+                               }
+                               theiroffset = -sp->ttis[j].tt_utoff;
+                               if (sp->ttis[j].tt_isdst)
+                                       theirstdoffset = theiroffset;
+                               else    theirdstoffset = theiroffset;
+                       }
+                       /*
+                       ** Finally, fill in ttis.
+                       */
+                       init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+                       init_ttinfo(&sp->ttis[1], -dstoffset, true,
+                           (int)(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);
+               init_ttinfo(&sp->ttis[1], 0, false, 0);
+               sp->defaulttype = 0;
+       }
+       sp->charcnt = (int)charcnt;
+       cp = sp->chars;
+       (void) memcpy(cp, stdname, stdlen);
+       cp += stdlen;
+       *cp++ = '\0';
+       if (dstlen != 0) {
+               (void) memcpy(cp, dstname, dstlen);
+               *(cp + dstlen) = '\0';
+       }
+       return true;
+}
+
+static void
+gmtload(struct state *const sp)
+{
+       if (tzload(gmt, sp, true) != 0)
+               (void) tzparse(gmt, sp, true);
+}
+
+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 = 1;
+               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;
+
+       if (! sp)
+               __lclptr = sp = malloc(sizeof *__lclptr);
+       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)
+{
+       rwlock_wrlock(&__lcl_lock);
+       tzsetlcl(NULL);
+       rwlock_unlock(&__lcl_lock);
+}
+#endif
+
+void
+tzset_unlocked(void)
+{
+       tzsetlcl(getenv("TZ"));
+}
+
+void
+tzset(void)
+{
+       rwlock_wrlock(&__lcl_lock);
+       tzset_unlocked();
+       rwlock_unlock(&__lcl_lock);
+}
+
+static void
+gmtcheck(void)
+{
+       static bool gmt_is_set;
+       rwlock_wrlock(&__lcl_lock);
+       if (! gmt_is_set) {
+               gmtptr = malloc(sizeof *gmtptr);
+               if (gmtptr)
+                       gmtload(gmtptr);
+               gmt_is_set = true;
+       }
+       rwlock_unlock(&__lcl_lock);
+}
+
+#if NETBSD_INSPIRED
+
+timezone_t
+tzalloc(const char *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 timezone 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)
+{
+       const struct ttinfo *   ttisp;
+       int                     i;
+       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;
+                       time_t          seconds;
+                       time_t          years;
+
+                       if (t < sp->ats[0])
+                               seconds = sp->ats[0] - t;
+                       else    seconds = t - sp->ats[sp->timecnt - 1];
+                       --seconds;
+                       years = (time_t)((seconds / SECSPERREPEAT + 1) * 
YEARSPERREPEAT);
+                       seconds = (time_t)(years * AVGSECSPERYEAR);
+                       if (t < sp->ats[0])
+                               newt += seconds;
+                       else    newt -= seconds;
+                       if (newt < sp->ats[0] ||
+                               newt > sp->ats[sp->timecnt - 1]) {
+                               errno = EINVAL;
+                               return NULL;    /* "cannot happen" */
+                       }
+                       result = localsub(sp, &newt, setname, tmp);
+                       if (result) {
+                               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)) {
+                                       errno = EOVERFLOW;
+                                       return NULL;
+                               }
+                               result->tm_year = (int)newy;
+                       }
+                       return result;
+       }
+       if (sp->timecnt == 0 || t < sp->ats[0]) {
+               i = sp->defaulttype;
+       } else {
+               int     lo = 1;
+               int     hi = sp->timecnt;
+
+               while (lo < hi) {
+                       int     mid = (lo + hi) / 2;
+
+                       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_utoff;
+       **      timesub(&t, 0L, sp, tmp);
+       */
+       result = timesub(&t, ttisp->tt_utoff, sp, tmp);
+       if (result) {
+               result->tm_isdst = ttisp->tt_isdst;
+#ifdef TM_ZONE
+               result->TM_ZONE = __UNCONST(&sp->chars[ttisp->tt_desigidx]);
+#endif /* defined TM_ZONE */
+               if (setname)
+                       update_tzname_etc(sp, ttisp);
+       }
+       return result;
+}
+
+#if NETBSD_INSPIRED
+
+struct tm *
+localtime_rz(timezone_t 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)
+{
+       rwlock_wrlock(&__lcl_lock);
+       if (setname || !lcl_is_set)
+               tzset_unlocked();
+       tmp = localsub(__lclptr, timep, setname, tmp);
+       rwlock_unlock(&__lcl_lock);
+       return tmp;
+}
+
+struct tm *
+localtime(const time_t *timep)
+{
+       return localtime_tzset(timep, &tm, true);
+}
+
+struct tm *
+localtime_r(const time_t * __restrict timep, struct tm *tmp)
+{
+       return localtime_tzset(timep, tmp, true);
+}
+
+/*
+** gmtsub is to gmtime as localsub is to localtime.
+*/
+
+static struct tm *
+gmtsub(struct state const *sp, const time_t *timep, int_fast32_t offset,
+       struct tm *tmp)
+{
+       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.
+       */
+       if (result)
+               result->TM_ZONE = offset ? __UNCONST(wildabbr) : gmtptr ?
+                   gmtptr->chars : __UNCONST(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(NULL, 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, (int_fast32_t)offset, &tm);
+}
+
+struct tm *
+offtime_r(const time_t *timep, long offset, struct tm *tmp)
+{
+       gmtcheck();
+       return gmtsub(NULL, timep, (int_fast32_t)offset, tmp);
+}
+
+#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
+
+/*
+** 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 ATTRIBUTE_PURE
+leaps_thru_end_of(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)
+{
+       const struct lsinfo *   lp;
+       time_t                  tdays;
+       int                     idays;  /* unsigned would be so 2003 */
+       int_fast64_t            rem;
+       int                     y;
+       const int *             ip;
+       int_fast64_t            corr;
+       int                     hit;
+       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 = (time_t)(*timep / SECSPERDAY);
+       rem = *timep % SECSPERDAY;
+       while (tdays < 0 || tdays >= year_lengths[isleap(y)]) {
+               int             newy;
+               time_t  tdelta;
+               int     idelta;
+               int     leapdays;
+
+               tdelta = tdays / DAYSPERLYEAR;
+               if (! ((! TYPE_SIGNED(time_t) || INT_MIN <= tdelta)
+                      && tdelta <= INT_MAX))
+                       goto out_of_range;
+               _DIAGASSERT(__type_fit(int, tdelta));
+               idelta = (int)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 = (int) 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;
+}
+
+char *
+ctime_rz(const timezone_t sp, const time_t * timep, char *buf)
+{
+       struct tm       mytm, *rtm;
+
+       rtm = localtime_rz(sp, timep, &mytm);
+       if (rtm == NULL)
+               return NULL;
+       return asctime_r(rtm, buf);
+}
+
+/*
+** 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  ((time_t)-1)
+#endif /* !defined WRONG */
+
+/*
+** Normalize logic courtesy Paul Eggert.
+*/
+
+static bool
+increment_overflow(int *ip, int j)
+{
+       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)
+{
+       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)
+{
+       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)
+{
+       int     tensdelta;
+
+       tensdelta = (*unitsptr >= 0) ?
+               (*unitsptr / base) :
+               (-1 - (-1 - *unitsptr) / base);
+       *unitsptr -= tensdelta * base;
+       return increment_overflow32(tensptr, tensdelta);
+}
+
+static int
+tmcomp(const struct tm *const atmp,
+       const struct tm *const btmp)
+{
+       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)
+{
+       int                     dir;
+       int                     i, j;
+       int                     saved_seconds;
+       int_fast32_t            li;
+       time_t                  lo;
+       time_t                  hi;
+#ifdef NO_ERROR_IN_DST_GAP
+       time_t                  ilo;
+#endif
+       int_fast32_t            y;
+       time_t                  newt;
+       time_t                  t;
+       struct tm               yourtm, mytm;
+
+       *okayp = false;
+       yourtm = *tmp;
+#ifdef NO_ERROR_IN_DST_GAP
+again:
+#endif
+       if (do_norm_secs) {
+               if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
+                   SECSPERMIN))
+                       goto out_of_range;
+       }
+       if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
+               goto out_of_range;
+       if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
+               goto out_of_range;
+       y = yourtm.tm_year;
+       if (normalize_overflow32(&y, &yourtm.tm_mon, MONSPERYEAR))
+               goto out_of_range;
+       /*
+       ** 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))
+               goto out_of_range;
+       while (yourtm.tm_mday <= 0) {
+               if (increment_overflow32(&y, -1))
+                       goto out_of_range;
+               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))
+                       goto out_of_range;
+       }
+       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))
+                               goto out_of_range;
+               }
+       }
+       if (increment_overflow32(&y, -TM_YEAR_BASE))
+               goto out_of_range;
+       if (! (INT_MIN <= y && y <= INT_MAX))
+               goto out_of_range;
+       yourtm.tm_year = (int)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))
+                       goto out_of_range;
+               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;
+#ifdef NO_ERROR_IN_DST_GAP
+       ilo = lo;
+#endif
+       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)
+                                       goto out_of_range;
+                               ++t;
+                               ++lo;
+                       } else if (t == hi) {
+                               if (t == TIME_T_MIN)
+                                       goto out_of_range;
+                               --t;
+                               --hi;
+                       }
+#ifdef NO_ERROR_IN_DST_GAP
+                       if (ilo != lo && lo - 1 == hi && yourtm.tm_isdst < 0 &&
+                           do_norm_secs) {
+                               for (i = sp->typecnt - 1; i >= 0; --i) {
+                                       for (j = sp->typecnt - 1; j >= 0; --j) {
+                                               time_t off;
+                                               if (sp->ttis[j].tt_isdst ==
+                                                   sp->ttis[i].tt_isdst)
+                                                       continue;
+                                               off = sp->ttis[j].tt_utoff -
+                                                   sp->ttis[i].tt_utoff;
+                                               yourtm.tm_sec += off < 0 ?
+                                                   -off : off;
+                                               goto again;
+                                       }
+                               }
+                       }
+#endif
+                       if (lo > hi)
+                               goto invalid;
+                       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 <=
+                              (/*CONSTCOND*/SMALLEST (INT_FAST32_MAX, LONG_MAX)
+                               + yourtm.TM_GMTOFF)))
+                       : (yourtm.TM_GMTOFF <= SECSPERDAY
+                          && ((/*CONSTCOND*/BIGGEST (INT_FAST32_MIN, LONG_MIN)
+                               + yourtm.TM_GMTOFF)
+                              <= mytm.TM_GMTOFF)))) {
+                 /* MYTM matches YOURTM except with the wrong UT 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 = (int_fast32_t)
+                     (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)) {
+                     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)
+                       goto invalid;
+               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 = (time_t)(t + sp->ttis[j].tt_utoff -
+                                   sp->ttis[i].tt_utoff);
+                               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;
+                       }
+               }
+               goto invalid;
+       }
+label:
+       newt = t + saved_seconds;
+       if ((newt < t) != (saved_seconds < 0))
+               goto out_of_range;
+       t = newt;
+       if (funcp(sp, &t, offset, tmp)) {
+               *okayp = true;
+               return t;
+       }
+out_of_range:
+       errno = EOVERFLOW;
+       return WRONG;
+invalid:
+       errno = EINVAL;
+       return WRONG;
+}
+
+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)
+{
+       time_t                  t;
+       int                     samei, otheri;
+       int                     sameind, otherind;
+       int                     i;
+       int                     nseen;
+       int                     save_errno;
+       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;
+       save_errno = errno;
+       t = time2(tmp, funcp, sp, offset, &okay);
+       if (okay) {
+               errno = save_errno;
+               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) {
+               errno = EINVAL;
+               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 += (int)(sp->ttis[otheri].tt_utoff -
+                                       sp->ttis[samei].tt_utoff);
+                       tmp->tm_isdst = !tmp->tm_isdst;
+                       t = time2(tmp, funcp, sp, offset, &okay);
+                       if (okay) {
+                               errno = save_errno;
+                               return t;
+                       }
+                       tmp->tm_sec -= (int)(sp->ttis[otheri].tt_utoff -
+                                       sp->ttis[samei].tt_utoff);
+                       tmp->tm_isdst = !tmp->tm_isdst;
+               }
+       }
+       errno = EOVERFLOW;
+       return WRONG;
+}
+
+static time_t
+mktime_tzname(timezone_t 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(timezone_t sp, struct tm *const tmp)
+{
+       return mktime_tzname(sp, tmp, false);
+}
+
+#endif
+
+time_t
+mktime(struct tm *tmp)
+{
+       time_t t;
+
+       rwlock_wrlock(&__lcl_lock);
+       tzset_unlocked();
+       t = mktime_tzname(__lclptr, tmp, true);
+       rwlock_unlock(&__lcl_lock);
+       return t;
+}
+
+#ifdef STD_INSPIRED
+
+time_t
+timelocal_z(const timezone_t sp, struct tm *const tmp)
+{
+       if (tmp != NULL)
+               tmp->tm_isdst = -1;     /* in case it wasn't initialized */
+       return mktime_z(sp, tmp);
+}
+
+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, (int_fast32_t)offset);
+}
+
+#endif /* defined STD_INSPIRED */
+
+/*
+** XXX--is the below the right way to conditionalize??
+*/
+
+#ifdef STD_INSPIRED
+
+/*
+** IEEE Std 1003.1 (POSIX) says 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(const timezone_t sp, time_t t)
+{
+       struct lsinfo const * lp;
+       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(timezone_t sp, time_t t)
+{
+       return (time_t)(t - leapcorr(sp, t));
+}
+
+time_t
+time2posix(time_t t)
+{
+       rwlock_wrlock(&__lcl_lock);
+       if (!lcl_is_set)
+               tzset_unlocked();
+       if (__lclptr)
+               t = (time_t)(t - leapcorr(__lclptr, t));
+       rwlock_unlock(&__lcl_lock);
+       return t;
+}
+
+NETBSD_INSPIRED_EXTERN time_t
+posix2time_z(timezone_t 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 = (time_t)(t + leapcorr(sp, t));
+       y = (time_t)(x - leapcorr(sp, x));
+       if (y < t) {
+               do {
+                       x++;
+                       y = (time_t)(x - leapcorr(sp, x));
+               } while (y < t);
+               x -= y != t;
+       } else if (y > t) {
+               do {
+                       --x;
+                       y = (time_t)(x - leapcorr(sp, x));
+               } while (y > t);
+               x += y != t;
+       }
+       return x;
+}
+
+time_t
+posix2time(time_t t)
+{
+       rwlock_wrlock(&__lcl_lock);
+       if (!lcl_is_set)
+               tzset_unlocked();
+       if (__lclptr)
+               t = posix2time_z(__lclptr, t);
+       rwlock_unlock(&__lcl_lock);
+       return t;
+}
+
+#endif /* defined STD_INSPIRED */
diff --git a/winsup/cygwin/tzcode/namespace.h b/winsup/cygwin/tzcode/namespace.h
new file mode 100644
index 000000000..e69de29bb
diff --git a/winsup/cygwin/tzcode/private.h b/winsup/cygwin/tzcode/private.h
new file mode 100644
index 000000000..830750ad5
--- /dev/null
+++ b/winsup/cygwin/tzcode/private.h
@@ -0,0 +1,795 @@
+/* Private header for tzdb code.  */
+
+/*     $NetBSD: private.h,v 1.55 2019/04/04 22:03:23 christos Exp $    */
+
+#ifndef PRIVATE_H
+#define PRIVATE_H
+
+/* NetBSD defaults */
+#define TM_GMTOFF      tm_gmtoff
+#define TM_ZONE                tm_zone
+#define STD_INSPIRED   1
+#define HAVE_LONG_DOUBLE 1
+
+/* For when we build zic as a host tool. */
+#if HAVE_NBTOOL_CONFIG_H
+#include "nbtool_config.h"
+#endif
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** zdump has been made independent of the rest of the time
+** conversion package to increase confidence in the verification it provides.
+** You can use zdump to help in verifying other implementations.
+** To do this, compile with -DUSE_LTZ=0 and link without the tz library.
+*/
+#ifndef USE_LTZ
+# define USE_LTZ 1
+#endif
+
+/* This string was in the Factory zone through version 2016f.  */
+#define GRANDPARENTED  "Local time zone must be set--see zic manual page"
+
+/*
+** Defaults for preprocessor symbols.
+** You can override these in your C compiler options, e.g. '-DHAVE_GETTEXT=1'.
+*/
+
+#ifndef HAVE_DECL_ASCTIME_R
+#define HAVE_DECL_ASCTIME_R 1
+#endif
+
+#if !defined HAVE_GENERIC && defined __has_extension
+# if __has_extension(c_generic_selections)
+#  define HAVE_GENERIC 1
+# else
+#  define HAVE_GENERIC 0
+# endif
+#endif
+/* _Generic is buggy in pre-4.9 GCC.  */
+#if !defined HAVE_GENERIC && defined __GNUC__
+# define HAVE_GENERIC (4 < __GNUC__ + (9 <= __GNUC_MINOR__))
+#endif
+#ifndef HAVE_GENERIC
+# define HAVE_GENERIC (201112 <= __STDC_VERSION__)
+#endif
+
+#ifndef HAVE_GETTEXT
+#define HAVE_GETTEXT           0
+#endif /* !defined HAVE_GETTEXT */
+
+#ifndef HAVE_INCOMPATIBLE_CTIME_R
+#define HAVE_INCOMPATIBLE_CTIME_R      0
+#endif
+
+#ifndef HAVE_LINK
+#define HAVE_LINK              1
+#endif /* !defined HAVE_LINK */
+
+#ifndef HAVE_POSIX_DECLS
+#define HAVE_POSIX_DECLS 1
+#endif
+
+#ifndef HAVE_STDBOOL_H
+#define HAVE_STDBOOL_H (199901 <= __STDC_VERSION__)
+#endif
+
+#ifndef HAVE_STRDUP
+#define HAVE_STRDUP 1
+#endif
+
+#ifndef HAVE_STRTOLL
+#define HAVE_STRTOLL 1
+#endif
+
+#ifndef HAVE_SYMLINK
+#define HAVE_SYMLINK           1
+#endif /* !defined HAVE_SYMLINK */
+
+#ifndef HAVE_SYS_STAT_H
+#define HAVE_SYS_STAT_H                1
+#endif /* !defined HAVE_SYS_STAT_H */
+
+#ifndef HAVE_SYS_WAIT_H
+#define HAVE_SYS_WAIT_H                1
+#endif /* !defined HAVE_SYS_WAIT_H */
+
+#ifndef HAVE_UNISTD_H
+#define HAVE_UNISTD_H          1
+#endif /* !defined HAVE_UNISTD_H */
+
+#ifndef HAVE_UTMPX_H
+#define HAVE_UTMPX_H           1
+#endif /* !defined HAVE_UTMPX_H */
+
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
+
+#if HAVE_INCOMPATIBLE_CTIME_R
+#define asctime_r _incompatible_asctime_r
+#define ctime_r _incompatible_ctime_r
+#endif /* HAVE_INCOMPATIBLE_CTIME_R */
+
+/* Enable tm_gmtoff, tm_zone, and environ on GNUish systems.  */
+#define _GNU_SOURCE 1
+/* Fix asctime_r on Solaris 11.  */
+#define _POSIX_PTHREAD_SEMANTICS 1
+/* Enable strtoimax on pre-C99 Solaris 11.  */
+#define __EXTENSIONS__ 1
+
+/* To avoid having 'stat' fail unnecessarily with errno == EOVERFLOW,
+   enable large files on GNUish systems ...  */
+#ifndef _FILE_OFFSET_BITS
+# define _FILE_OFFSET_BITS 64
+#endif
+/* ... and on AIX ...  */
+#define _LARGE_FILES 1
+/* ... and enable large inode numbers on Mac OS X 10.5 and later.  */
+#define _DARWIN_USE_64_BIT_INODE 1
+
+/*
+** Nested includes
+*/
+
+#ifndef __NetBSD__
+/* Avoid clashes with NetBSD by renaming NetBSD's declarations.  */
+#define localtime_rz sys_localtime_rz
+#define mktime_z sys_mktime_z
+#define posix2time_z sys_posix2time_z
+#define time2posix_z sys_time2posix_z
+#define timezone_t sys_timezone_t
+#define tzalloc sys_tzalloc
+#define tzfree sys_tzfree
+#include <time.h>
+#undef localtime_rz
+#undef mktime_z
+#undef posix2time_z
+#undef time2posix_z
+#undef timezone_t
+#undef tzalloc
+#undef tzfree
+#else
+#include "time.h"
+#endif
+
+#include <sys/types.h> /* for time_t */
+#include <string.h>
+#include <limits.h>    /* for CHAR_BIT et al. */
+#include <stdlib.h>
+
+#include <errno.h>
+
+#ifndef ENAMETOOLONG
+# define ENAMETOOLONG EINVAL
+#endif
+#ifndef ENOTSUP
+# define ENOTSUP EINVAL
+#endif
+#ifndef EOVERFLOW
+# define EOVERFLOW EINVAL
+#endif
+
+#if HAVE_GETTEXT
+#include <libintl.h>
+#endif /* HAVE_GETTEXT */
+
+#if HAVE_UNISTD_H
+#include <unistd.h>    /* for R_OK, and other POSIX goodness */
+#endif /* HAVE_UNISTD_H */
+
+#ifndef HAVE_STRFTIME_L
+# if _POSIX_VERSION < 200809
+#  define HAVE_STRFTIME_L 0
+# else
+#  define HAVE_STRFTIME_L 1
+# endif
+#endif
+
+#ifndef USG_COMPAT
+# ifndef _XOPEN_VERSION
+#  define USG_COMPAT 0
+# else
+#  define USG_COMPAT 1
+# endif
+#endif
+
+#ifndef HAVE_TZNAME
+# if _POSIX_VERSION < 198808 && !USG_COMPAT
+#  define HAVE_TZNAME 0
+# else
+#  define HAVE_TZNAME 1
+# endif
+#endif
+
+#ifndef R_OK
+#define R_OK   4
+#endif /* !defined R_OK */
+
+/* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
+#define is_digit(c) ((unsigned)(c) - '0' <= 9)
+
+/*
+** Define HAVE_STDINT_H's default value here, rather than at the
+** start, since __GLIBC__ and INTMAX_MAX's values depend on
+** previously-included files.  glibc 2.1 and Solaris 10 and later have
+** stdint.h, even with pre-C99 compilers.
+*/
+#ifndef HAVE_STDINT_H
+#define HAVE_STDINT_H \
+   (199901 <= __STDC_VERSION__ \
+    || 2 < __GLIBC__ + (1 <= __GLIBC_MINOR__)  \
+    || __CYGWIN__ || INTMAX_MAX)
+#endif /* !defined HAVE_STDINT_H */
+
+#if HAVE_STDINT_H
+#include <stdint.h>
+#endif /* !HAVE_STDINT_H */
+
+#ifndef HAVE_INTTYPES_H
+# define HAVE_INTTYPES_H HAVE_STDINT_H
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#endif
+
+/* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
+#ifdef __LONG_LONG_MAX__
+# ifndef LLONG_MAX
+#  define LLONG_MAX __LONG_LONG_MAX__
+# endif
+# ifndef LLONG_MIN
+#  define LLONG_MIN (-1 - LLONG_MAX)
+# endif
+#endif
+
+#ifndef INT_FAST64_MAX
+# ifdef LLONG_MAX
+typedef long long      int_fast64_t;
+#  define INT_FAST64_MIN LLONG_MIN
+#  define INT_FAST64_MAX LLONG_MAX
+# else
+#  if LONG_MAX >> 31 < 0xffffffff
+Please use a compiler that supports a 64-bit integer type (or wider);
+you may need to compile with "-DHAVE_STDINT_H".
+#  endif
+typedef long           int_fast64_t;
+#  define INT_FAST64_MIN LONG_MIN
+#  define INT_FAST64_MAX LONG_MAX
+# endif
+#endif
+
+#ifndef PRIdFAST64
+# if INT_FAST64_MAX == LLONG_MAX
+#  define PRIdFAST64 "lld"
+# else
+#  define PRIdFAST64 "ld"
+# endif
+#endif
+
+#ifndef SCNdFAST64
+# define SCNdFAST64 PRIdFAST64
+#endif
+
+#ifndef INT_FAST32_MAX
+# if INT_MAX >> 31 == 0
+typedef long int_fast32_t;
+#  define INT_FAST32_MAX LONG_MAX
+#  define INT_FAST32_MIN LONG_MIN
+# else
+typedef int int_fast32_t;
+#  define INT_FAST32_MAX INT_MAX
+#  define INT_FAST32_MIN INT_MIN
+# endif
+#endif
+
+#ifndef INTMAX_MAX
+# ifdef LLONG_MAX
+typedef long long intmax_t;
+#  if HAVE_STRTOLL
+#   define strtoimax strtoll
+#  endif
+#  define INTMAX_MAX LLONG_MAX
+#  define INTMAX_MIN LLONG_MIN
+# else
+typedef long intmax_t;
+#  define INTMAX_MAX LONG_MAX
+#  define INTMAX_MIN LONG_MIN
+# endif
+# ifndef strtoimax
+#  define strtoimax strtol
+# endif
+#endif
+
+#ifndef PRIdMAX
+# if INTMAX_MAX == LLONG_MAX
+#  define PRIdMAX "lld"
+# else
+#  define PRIdMAX "ld"
+# endif
+#endif
+
+#ifndef UINT_FAST64_MAX
+# if defined ULLONG_MAX || defined __LONG_LONG_MAX__
+typedef unsigned long long uint_fast64_t;
+# else
+#  if ULONG_MAX >> 31 >> 1 < 0xffffffff
+Please use a compiler that supports a 64-bit integer type (or wider);
+you may need to compile with "-DHAVE_STDINT_H".
+#  endif
+typedef unsigned long  uint_fast64_t;
+# endif
+#endif
+
+#ifndef UINTMAX_MAX
+# if defined ULLONG_MAX || defined __LONG_LONG_MAX__
+typedef unsigned long long uintmax_t;
+# else
+typedef unsigned long uintmax_t;
+# endif
+#endif
+
+#ifndef PRIuMAX
+# if defined ULLONG_MAX || defined __LONG_LONG_MAX__
+#  define PRIuMAX "llu"
+# else
+#  define PRIuMAX "lu"
+# endif
+#endif
+
+#ifndef INT32_MAX
+#define INT32_MAX 0x7fffffff
+#endif /* !defined INT32_MAX */
+#ifndef INT32_MIN
+#define INT32_MIN (-1 - INT32_MAX)
+#endif /* !defined INT32_MIN */
+
+#ifndef SIZE_MAX
+#define SIZE_MAX ((size_t) -1)
+#endif
+
+#if 3 <= __GNUC__
+# define ATTRIBUTE_CONST __attribute__ ((__const__))
+# define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
+# define ATTRIBUTE_PURE __attribute__ ((__pure__))
+# define ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
+#else
+# define ATTRIBUTE_CONST /* empty */
+# define ATTRIBUTE_MALLOC /* empty */
+# define ATTRIBUTE_PURE /* empty */
+# define ATTRIBUTE_FORMAT(spec) /* empty */
+#endif
+
+#if !defined _Noreturn && __STDC_VERSION__ < 201112
+# if 2 < __GNUC__ + (8 <= __GNUC_MINOR__)
+#  define _Noreturn __attribute__ ((__noreturn__))
+# else
+#  define _Noreturn
+# endif
+#endif
+
+#if __STDC_VERSION__ < 199901 && !defined restrict
+# define restrict /* empty */
+#endif
+
+/*
+** Workarounds for compilers/systems.
+*/
+
+#ifndef EPOCH_LOCAL
+# define EPOCH_LOCAL 0
+#endif
+#ifndef EPOCH_OFFSET
+# define EPOCH_OFFSET 0
+#endif
+#ifndef RESERVE_STD_EXT_IDS
+# define RESERVE_STD_EXT_IDS 0
+#endif
+
+/* If standard C identifiers with external linkage (e.g., localtime)
+   are reserved and are not already being renamed anyway, rename them
+   as if compiling with '-Dtime_tz=time_t'.  */
+#if !defined time_tz && RESERVE_STD_EXT_IDS && USE_LTZ
+# define time_tz time_t
+#endif
+
+/*
+** Compile with -Dtime_tz=T to build the tz package with a private
+** time_t type equivalent to T rather than the system-supplied time_t.
+** This debugging feature can test unusual design decisions
+** (e.g., time_t wider than 'long', or unsigned time_t) even on
+** typical platforms.
+*/
+#if defined time_tz || EPOCH_LOCAL || EPOCH_OFFSET != 0
+# define TZ_TIME_T 1
+#else
+# define TZ_TIME_T 0
+#endif
+
+#if TZ_TIME_T
+# ifdef LOCALTIME_IMPLEMENTATION
+static time_t sys_time(time_t *x) { return time(x); }
+# endif
+
+typedef time_tz tz_time_t;
+
+# undef  ctime
+# define ctime tz_ctime
+# undef  ctime_r
+# define ctime_r tz_ctime_r
+# undef  difftime
+# define difftime tz_difftime
+# undef  gmtime
+# define gmtime tz_gmtime
+# undef  gmtime_r
+# define gmtime_r tz_gmtime_r
+# undef  localtime
+# define localtime tz_localtime
+# undef  localtime_r
+# define localtime_r tz_localtime_r
+# undef  localtime_rz
+# define localtime_rz tz_localtime_rz
+# undef  mktime
+# define mktime tz_mktime
+# undef  mktime_z
+# define mktime_z tz_mktime_z
+# undef  offtime
+# define offtime tz_offtime
+# undef  posix2time
+# define posix2time tz_posix2time
+# undef  posix2time_z
+# define posix2time_z tz_posix2time_z
+# undef  strftime
+# define strftime tz_strftime
+# undef  time
+# define time tz_time
+# undef  time2posix
+# define time2posix tz_time2posix
+# undef  time2posix_z
+# define time2posix_z tz_time2posix_z
+# undef  time_t
+# define time_t tz_time_t
+# undef  timegm
+# define timegm tz_timegm
+# undef  timelocal
+# define timelocal tz_timelocal
+# undef  timeoff
+# define timeoff tz_timeoff
+# undef  tzalloc
+# define tzalloc tz_tzalloc
+# undef  tzfree
+# define tzfree tz_tzfree
+# undef  tzset
+# define tzset tz_tzset
+# undef  tzsetwall
+# define tzsetwall tz_tzsetwall
+# if HAVE_STRFTIME_L
+#  undef  strftime_l
+#  define strftime_l tz_strftime_l
+# endif
+# if HAVE_TZNAME
+#  undef  tzname
+#  define tzname tz_tzname
+# endif
+# if USG_COMPAT
+#  undef  daylight
+#  define daylight tz_daylight
+#  undef  timezone
+#  define timezone tz_timezone
+# endif
+# ifdef ALTZONE
+#  undef  altzone
+#  define altzone tz_altzone
+# endif
+
+char *ctime(time_t const *);
+char *ctime_r(time_t const *, char *);
+double difftime(time_t, time_t) ATTRIBUTE_CONST;
+size_t strftime(char *restrict, size_t, char const *restrict,
+               struct tm const *restrict);
+# if HAVE_STRFTIME_L
+size_t strftime_l(char *restrict, size_t, char const *restrict,
+                 struct tm const *restrict, locale_t);
+# endif
+struct tm *gmtime(time_t const *);
+struct tm *gmtime_r(time_t const *restrict, struct tm *restrict);
+struct tm *localtime(time_t const *);
+struct tm *localtime_r(time_t const *restrict, struct tm *restrict);
+time_t mktime(struct tm *);
+time_t time(time_t *);
+void tzset(void);
+#endif
+
+#if !HAVE_DECL_ASCTIME_R && !defined asctime_r
+extern char *asctime_r(struct tm const *restrict, char *restrict);
+#endif
+
+#ifndef HAVE_DECL_ENVIRON
+# if defined environ || defined __USE_GNU
+#  define HAVE_DECL_ENVIRON 1
+# else
+#  define HAVE_DECL_ENVIRON 0
+# endif
+#endif
+
+#if !HAVE_DECL_ENVIRON
+extern char **environ;
+#endif
+
+#if TZ_TIME_T || !HAVE_POSIX_DECLS
+# if HAVE_TZNAME
+extern char *tzname[];
+# endif
+# if USG_COMPAT
+extern long timezone;
+extern int daylight;
+# endif
+#endif
+
+#ifdef ALTZONE
+extern long altzone;
+#endif
+
+/*
+** The STD_INSPIRED functions are similar, but most also need
+** declarations if time_tz is defined.
+*/
+
+#ifdef STD_INSPIRED
+# if TZ_TIME_T || !defined tzsetwall
+void tzsetwall(void);
+# endif
+# if TZ_TIME_T || !defined offtime
+struct tm *offtime(time_t const *, long);
+# endif
+# if TZ_TIME_T || !defined timegm
+time_t timegm(struct tm *);
+# endif
+# if TZ_TIME_T || !defined timelocal
+time_t timelocal(struct tm *);
+# endif
+# if TZ_TIME_T || !defined timeoff
+time_t timeoff(struct tm *, long);
+# endif
+# if TZ_TIME_T || !defined time2posix
+time_t time2posix(time_t);
+# endif
+# if TZ_TIME_T || !defined posix2time
+time_t posix2time(time_t);
+# endif
+#endif
+
+/* Infer TM_ZONE on systems where this information is known, but suppress
+   guessing if NO_TM_ZONE is defined.  Similarly for TM_GMTOFF.  */
+#if (defined __GLIBC__ \
+     || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \
+     || (defined __APPLE__ && defined __MACH__))
+# if !defined TM_GMTOFF && !defined NO_TM_GMTOFF
+#  define TM_GMTOFF tm_gmtoff
+# endif
+# if !defined TM_ZONE && !defined NO_TM_ZONE
+#  define TM_ZONE tm_zone
+# endif
+#endif
+
+/*
+** Define functions that are ABI compatible with NetBSD but have
+** better prototypes.  NetBSD 6.1.4 defines a pointer type timezone_t
+** and labors under the misconception that 'const timezone_t' is a
+** pointer to a constant.  This use of 'const' is ineffective, so it
+** is not done here.  What we call 'struct state' NetBSD calls
+** 'struct __state', but this is a private name so it doesn't matter.
+*/
+#ifndef __NetBSD__
+#if NETBSD_INSPIRED
+typedef struct state *timezone_t;
+struct tm *localtime_rz(timezone_t restrict, time_t const *restrict,
+                       struct tm *restrict);
+time_t mktime_z(timezone_t restrict, struct tm *restrict);
+timezone_t tzalloc(char const *);
+void tzfree(timezone_t);
+# ifdef STD_INSPIRED
+#  if TZ_TIME_T || !defined posix2time_z
+time_t posix2time_z(timezone_t __restrict, time_t) ATTRIBUTE_PURE;
+#  endif
+#  if TZ_TIME_T || !defined time2posix_z
+time_t time2posix_z(timezone_t __restrict, time_t) ATTRIBUTE_PURE;
+#  endif
+# endif
+#endif
+#endif
+
+/*
+** Finally, some convenience items.
+*/
+
+#if HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# define true 1
+# define false 0
+# define bool int
+#endif
+
+#define TYPE_BIT(type) (sizeof (type) * CHAR_BIT)
+#define TYPE_SIGNED(type) (/*CONSTCOND*/((type) -1) < 0)
+#define TWOS_COMPLEMENT(t) (/*CONSTCOND*/(t) ~ (t) 0 < 0)
+
+/* Max and min values of the integer type T, of which only the bottom
+   B bits are used, and where the highest-order used bit is considered
+   to be a sign bit if T is signed.  */
+#define MAXVAL(t, b) /*LINTED*/                                        \
+  ((t) (((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))                  \
+       - 1 + ((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))))
+#define MINVAL(t, b)                                           \
+  ((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
+
+/* The extreme time values, assuming no padding.  */
+#define TIME_T_MIN_NO_PADDING MINVAL(time_t, TYPE_BIT(time_t))
+#define TIME_T_MAX_NO_PADDING MAXVAL(time_t, TYPE_BIT(time_t))
+
+/* The extreme time values.  These are macros, not constants, so that
+   any portability problem occur only when compiling .c files that use
+   the macros, which is safer for applications that need only zdump and zic.
+   This implementation assumes no padding if time_t is signed and
+   either the compiler lacks support for _Generic or time_t is not one
+   of the standard signed integer types.  */
+#if HAVE_GENERIC
+# define TIME_T_MIN \
+    _Generic((time_t) 0, \
+            signed char: SCHAR_MIN, short: SHRT_MIN, \
+            int: INT_MIN, long: LONG_MIN, long long: LLONG_MIN, \
+            default: TIME_T_MIN_NO_PADDING)
+# define TIME_T_MAX \
+    (TYPE_SIGNED(time_t) \
+     ? _Generic((time_t) 0, \
+               signed char: SCHAR_MAX, short: SHRT_MAX, \
+               int: INT_MAX, long: LONG_MAX, long long: LLONG_MAX, \
+               default: TIME_T_MAX_NO_PADDING)                     \
+     : (time_t) -1)
+#else
+# define TIME_T_MIN TIME_T_MIN_NO_PADDING
+# define TIME_T_MAX TIME_T_MAX_NO_PADDING
+#endif
+
+/*
+** 302 / 1000 is log10(2.0) rounded up.
+** Subtract one for the sign bit if the type is signed;
+** add one for integer division truncation;
+** add one more for a minus sign if the type is signed.
+*/
+#define INT_STRLEN_MAXIMUM(type) \
+       ((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
+       1 + TYPE_SIGNED(type))
+
+/*
+** INITIALIZE(x)
+*/
+
+#if defined(__GNUC__) || defined(__lint__)
+# define INITIALIZE(x) ((x) = 0)
+#else
+# define INITIALIZE(x)
+#endif
+
+#ifndef UNINIT_TRAP
+# define UNINIT_TRAP 0
+#endif
+
+/*
+** For the benefit of GNU folk...
+** '_(MSGID)' uses the current locale's message library string for MSGID.
+** The default is to use gettext if available, and use MSGID otherwise.
+*/
+
+#if HAVE_GETTEXT
+#define _(msgid) gettext(msgid)
+#else /* !HAVE_GETTEXT */
+#define _(msgid) msgid
+#endif /* !HAVE_GETTEXT */
+
+#if !defined TZ_DOMAIN && defined HAVE_GETTEXT
+# define TZ_DOMAIN "tz"
+#endif
+
+#if HAVE_INCOMPATIBLE_CTIME_R
+#undef asctime_r
+#undef ctime_r
+char *asctime_r(struct tm const *, char *);
+char *ctime_r(time_t const *, char *);
+#endif /* HAVE_INCOMPATIBLE_CTIME_R */
+
+/* Handy macros that are independent of tzfile implementation.  */
+
+#define YEARSPERREPEAT         400     /* years before a Gregorian repeat */
+
+#define SECSPERMIN     60
+#define MINSPERHOUR    60
+#define HOURSPERDAY    24
+#define DAYSPERWEEK    7
+#define DAYSPERNYEAR   365
+#define DAYSPERLYEAR   366
+#define SECSPERHOUR    (SECSPERMIN * MINSPERHOUR)
+#define SECSPERDAY     ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
+#define MONSPERYEAR    12
+
+#define TM_SUNDAY      0
+#define TM_MONDAY      1
+#define TM_TUESDAY     2
+#define TM_WEDNESDAY   3
+#define TM_THURSDAY    4
+#define TM_FRIDAY      5
+#define TM_SATURDAY    6
+
+#define TM_JANUARY     0
+#define TM_FEBRUARY    1
+#define TM_MARCH       2
+#define TM_APRIL       3
+#define TM_MAY         4
+#define TM_JUNE                5
+#define TM_JULY                6
+#define TM_AUGUST      7
+#define TM_SEPTEMBER   8
+#define TM_OCTOBER     9
+#define TM_NOVEMBER    10
+#define TM_DECEMBER    11
+
+#define TM_YEAR_BASE   1900
+
+#define EPOCH_YEAR     1970
+#define EPOCH_WDAY     TM_THURSDAY
+
+#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
+
+/*
+** Since everything in isleap is modulo 400 (or a factor of 400), we know that
+**     isleap(y) == isleap(y % 400)
+** and so
+**     isleap(a + b) == isleap((a + b) % 400)
+** or
+**     isleap(a + b) == isleap(a % 400 + b % 400)
+** This is true even if % means modulo rather than Fortran remainder
+** (which is allowed by C89 but not by C99 or later).
+** We use this to avoid addition overflow problems.
+*/
+
+#define isleap_sum(a, b)       isleap((a) % 400 + (b) % 400)
+
+
+/*
+** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
+*/
+
+#define AVGSECSPERYEAR         31556952L
+#define SECSPERREPEAT \
+  ((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
+#define SECSPERREPEAT_BITS     34      /* ceil(log2(SECSPERREPEAT)) */
+
+#ifdef _LIBC
+#include "reentrant.h"
+extern struct __state *__lclptr;
+#if defined(__LIBC12_SOURCE__)
+#define tzset_unlocked __tzset_unlocked
+#else
+#define tzset_unlocked __tzset_unlocked50
+#endif
+
+void tzset_unlocked(void);
+#ifdef _REENTRANT
+extern rwlock_t __lcl_lock;
+#endif
+#endif
+
+#endif /* !defined PRIVATE_H */
diff --git a/winsup/cygwin/tzcode/tzfile.h b/winsup/cygwin/tzcode/tzfile.h
new file mode 100644
index 000000000..5c7a22239
--- /dev/null
+++ b/winsup/cygwin/tzcode/tzfile.h
@@ -0,0 +1,174 @@
+/*     $NetBSD: tzfile.h,v 1.10 2019/07/03 15:49:21 christos Exp $     */
+
+#ifndef _TZFILE_H_
+#define _TZFILE_H_
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** Information about time zone files.
+*/
+
+#ifndef TZDIR          /* Time zone object file directory */
+#define TZDIR          "/usr/share/zoneinfo"
+#endif /* !defined TZDIR */
+
+#ifndef TZDEFAULT
+#define TZDEFAULT      "/etc/localtime"
+#endif /* !defined TZDEFAULT */
+
+#ifndef TZDEFRULES
+#define TZDEFRULES     "posixrules"
+#endif /* !defined TZDEFRULES */
+
+
+/* See Internet RFC 8536 for more details about the following format.  */
+
+/*
+** Each file begins with. . .
+*/
+
+#define        TZ_MAGIC        "TZif"
+
+struct tzhead {
+       char    tzh_magic[4];           /* TZ_MAGIC */
+       char    tzh_version[1];         /* '\0' or '2' or '3' as of 2013 */
+       char    tzh_reserved[15];       /* reserved; must be zero */
+       char    tzh_ttisutcnt[4];       /* coded number of trans. time flags */
+       char    tzh_ttisstdcnt[4];      /* coded number of trans. time flags */
+       char    tzh_leapcnt[4];         /* coded number of leap seconds */
+       char    tzh_timecnt[4];         /* coded number of transition times */
+       char    tzh_typecnt[4];         /* coded number of local time types */
+       char    tzh_charcnt[4];         /* coded number of abbr. chars */
+};
+
+/*
+** . . .followed by. . .
+**
+**     tzh_timecnt (char [4])s         coded transition times a la time(2)
+**     tzh_timecnt (unsigned char)s    types of local time starting at above
+**     tzh_typecnt repetitions of
+**             one (char [4])          coded UT offset in seconds
+**             one (unsigned char)     used to set tm_isdst
+**             one (unsigned char)     that's an abbreviation list index
+**     tzh_charcnt (char)s             '\0'-terminated zone abbreviations
+**     tzh_leapcnt repetitions of
+**             one (char [4])          coded leap second transition times
+**             one (char [4])          total correction after above
+**     tzh_ttisstdcnt (char)s          indexed by type; if 1, transition
+**                                     time is standard time, if 0,
+**                                     transition time is local (wall clock)
+**                                     time; if absent, transition times are
+**                                     assumed to be local time
+**     tzh_ttisutcnt (char)s           indexed by type; if 1, transition
+**                                     time is UT, if 0, transition time is
+**                                     local time; if absent, transition
+**                                     times are assumed to be local time.
+**                                     When this is 1, the corresponding
+**                                     std/wall indicator must also be 1.
+*/
+
+/*
+** If tzh_version is '2' or greater, the above is followed by a second instance
+** of tzhead and a second instance of the data in which each coded transition
+** time uses 8 rather than 4 chars,
+** then a POSIX-TZ-environment-variable-style string for use in handling
+** instants after the last transition time stored in the file
+** (with nothing between the newlines if there is no POSIX representation for
+** such instants).
+**
+** If tz_version is '3' or greater, the above is extended as follows.
+** First, the POSIX TZ string's hour offset may range from -167
+** through 167 as compared to the POSIX-required 0 through 24.
+** Second, its DST start time may be January 1 at 00:00 and its stop
+** time December 31 at 24:00 plus the difference between DST and
+** standard time, indicating DST all year.
+*/
+
+/*
+** In the current implementation, "tzset()" refuses to deal with files that
+** exceed any of the limits below.
+*/
+
+#ifndef TZ_MAX_TIMES
+#define TZ_MAX_TIMES   2000
+#endif /* !defined TZ_MAX_TIMES */
+
+#ifndef TZ_MAX_TYPES
+/* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
+#define TZ_MAX_TYPES   256 /* Limited by what (unsigned char)'s can hold */
+#endif /* !defined TZ_MAX_TYPES */
+
+#ifndef TZ_MAX_CHARS
+#define TZ_MAX_CHARS   50      /* Maximum number of abbreviation characters */
+                               /* (limited by what unsigned chars can hold) */
+#endif /* !defined TZ_MAX_CHARS */
+
+#ifndef TZ_MAX_LEAPS
+#define TZ_MAX_LEAPS   50      /* Maximum number of leap second corrections */
+#endif /* !defined TZ_MAX_LEAPS */
+
+#define SECSPERMIN     60
+#define MINSPERHOUR    60
+#define HOURSPERDAY    24
+#define DAYSPERWEEK    7
+#define DAYSPERNYEAR   365
+#define DAYSPERLYEAR   366
+#define SECSPERHOUR    (SECSPERMIN * MINSPERHOUR)
+#define SECSPERDAY     ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
+#define MONSPERYEAR    12
+
+#define TM_SUNDAY      0
+#define TM_MONDAY      1
+#define TM_TUESDAY     2
+#define TM_WEDNESDAY   3
+#define TM_THURSDAY    4
+#define TM_FRIDAY      5
+#define TM_SATURDAY    6
+
+#define TM_JANUARY     0
+#define TM_FEBRUARY    1
+#define TM_MARCH       2
+#define TM_APRIL       3
+#define TM_MAY         4
+#define TM_JUNE                5
+#define TM_JULY                6
+#define TM_AUGUST      7
+#define TM_SEPTEMBER   8
+#define TM_OCTOBER     9
+#define TM_NOVEMBER    10
+#define TM_DECEMBER    11
+
+#define TM_YEAR_BASE   1900
+
+#define EPOCH_YEAR     1970
+#define EPOCH_WDAY     TM_THURSDAY
+
+#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
+
+/*
+** Since everything in isleap is modulo 400 (or a factor of 400), we know that
+**     isleap(y) == isleap(y % 400)
+** and so
+**     isleap(a + b) == isleap((a + b) % 400)
+** or
+**     isleap(a + b) == isleap(a % 400 + b % 400)
+** This is true even if % means modulo rather than Fortran remainder
+** (which is allowed by C89 but not C99).
+** We use this to avoid addition overflow problems.
+*/
+
+#define isleap_sum(a, b)       isleap((a) % 400 + (b) % 400)
+
+#endif /* !defined _TZFILE_H_ */
-- 
2.21.0

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