From d3acfece4683a669e8d583787eb36b75f3323ac7 Mon Sep 17 00:00:00 2001
From: Timur Safin <tsafin@tarantool.org>
Date: Thu, 28 Apr 2022 20:16:53 +0300
Subject: [PATCH] datetime, build - tzcode/olson integrated into cmake

- localtime.c, tzfile.h added to build

NO_DOC=build
NO_CHANGELOG=build
NO_TEST=build
---
 src/lib/tzcode/CMakeLists.txt |   32 +-
 src/lib/tzcode/localtime.c    | 1824 +++++++++++++++++++++++++++++++++
 src/lib/tzcode/private.h      |  241 ++++-
 src/lib/tzcode/tzfile.h       |  122 +++
 4 files changed, 2217 insertions(+), 2 deletions(-)
 create mode 100644 src/lib/tzcode/localtime.c
 create mode 100644 src/lib/tzcode/tzfile.h

diff --git a/src/lib/tzcode/CMakeLists.txt b/src/lib/tzcode/CMakeLists.txt
index 3d4662856b..0157f9c267 100644
--- a/src/lib/tzcode/CMakeLists.txt
+++ b/src/lib/tzcode/CMakeLists.txt
@@ -1,2 +1,32 @@
-add_library(tzcode STATIC strftime.c strptime.c timelocal.c timezone.c)
+add_library(tzcode STATIC
+            strftime.c strptime.c timelocal.c localtime.c timezone.c)
 target_link_libraries(tzcode)
+
+set(TZCODE_PROJECT tzcode-iana)
+set(TZCODE_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR})
+set(TZCODE_PREFIX ${TZCODE_BUILD_DIR}/tz)
+set(TZDATA_TARGET main.zi)
+
+set(TZDATA_FULL_TARGET
+    ${TZCODE_PREFIX}/src/${TZCODE_PROJECT}/${TZDATA_TARGET})
+
+ExternalProject_Add(${TZCODE_PROJECT}
+    GIT_REPOSITORY https://github.com/tarantool/tz
+    GIT_TAG 2022a
+    GIT_SHALLOW YES
+
+    INSTALL_DIR ${TZCODE_BUILD_DIR}/install
+
+    UPDATE_COMMAND ""
+    CONFIGURE_COMMAND ""
+
+    BUILD_COMMAND ${CMAKE_COMMAND} -E env
+        CC=${CMAKE_C_COMPILER}
+        CFLAGS=${CMAKE_C_FLAGS}
+        PACKRATDATA=backzone
+        make -C <SOURCE_DIR> ${TZDATA_TARGET}
+    BUILD_IN_SOURCE TRUE
+    TEST_COMMAND ""
+    INSTALL_COMMAND make DESTDIR=<INSTALL_DIR> install
+    BUILD_BYPRODUCTS ${TZDATA_FULL_TARGET}
+)
diff --git a/src/lib/tzcode/localtime.c b/src/lib/tzcode/localtime.c
new file mode 100644
index 0000000000..d2482a1949
--- /dev/null
+++ b/src/lib/tzcode/localtime.c
@@ -0,0 +1,1824 @@
+/* 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.
+*/
+
+/*
+** Leap second handling from Bradley White.
+** POSIX-style TZ environment variable handling from Guy Harris.
+*/
+
+/*LINTLIBRARY*/
+
+#include <unistd.h>
+#define LOCALTIME_IMPLEMENTATION
+#include "private.h"
+
+#include "tzfile.h"
+#include <fcntl.h>
+
+#ifndef TZ_ABBR_MAX_LEN
+#define TZ_ABBR_MAX_LEN 16
+#endif /* !defined TZ_ABBR_MAX_LEN */
+
+#ifndef TZ_ABBR_CHAR_SET
+#define TZ_ABBR_CHAR_SET                                                       \
+	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
+#endif /* !defined TZ_ABBR_CHAR_SET */
+
+#ifndef TZ_ABBR_ERR_CHAR
+#define TZ_ABBR_ERR_CHAR '_'
+#endif /* !defined TZ_ABBR_ERR_CHAR */
+
+/*
+** SunOS 4.1.1 headers lack O_BINARY.
+*/
+
+#ifdef O_BINARY
+#define OPEN_MODE (O_RDONLY | O_BINARY)
+#endif /* defined O_BINARY */
+#ifndef O_BINARY
+#define OPEN_MODE O_RDONLY
+#endif /* !defined O_BINARY */
+
+#ifndef WILDABBR
+/*
+** Someone might make incorrect use of a time zone abbreviation:
+**	1.	They might reference tzname[0] before calling tzset (explicitly
+**		or implicitly).
+**	2.	They might reference tzname[1] before calling tzset (explicitly
+**		or implicitly).
+**	3.	They might reference tzname[1] after setting to a time zone
+**		in which Daylight Saving Time is never observed.
+**	4.	They might reference tzname[0] after setting to a time zone
+**		in which Standard Time is never observed.
+**	5.	They might reference tm.TM_ZONE after calling offtime.
+** What's best to do in the above cases is open to debate;
+** for now, we just set things up so that in any of the five cases
+** WILDABBR is used. Another possibility: initialize tzname[0] to the
+** string "tzname[0] used before set", and similarly for the other cases.
+** And another: initialize tzname[0] to "ERA", with an explanation in the
+** manual page of what this "time zone abbreviation" means (doing this so
+** that tzname[0] has the "normal" length of three characters).
+*/
+#define WILDABBR "   "
+#endif /* !defined WILDABBR */
+
+static const char wildabbr[] = WILDABBR;
+
+static const char gmt[] = "GMT";
+
+/*
+** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
+** Default to US rules as of 2017-05-07.
+** POSIX 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_fast32_t ls_corr; /* correction to apply */
+};
+
+#define SMALLEST(a, b) (((a) < (b)) ? (a) : (b))
+#define BIGGEST(a, b) (((a) > (b)) ? (a) : (b))
+
+/* This abbreviation means local time is unspecified.  */
+static char const UNSPEC[] = "-00";
+
+/* How many extra bytes are needed at the end of struct state's chars array.
+   This needs to be at least 1 for null termination in case the input
+   data isn't properly terminated, and it also needs to be big enough
+   for ttunspecified to work without crashing.  */
+enum { CHARS_EXTRA = BIGGEST(sizeof UNSPEC, 2) - 1 };
+
+#ifdef TZNAME_MAX
+#define MY_TZNAME_MAX TZNAME_MAX
+#endif /* defined TZNAME_MAX */
+#ifndef TZNAME_MAX
+#define MY_TZNAME_MAX 255
+#endif /* !defined TZNAME_MAX */
+
+struct state {
+	int leapcnt;
+	int timecnt;
+	int typecnt;
+	int charcnt;
+	bool goback;
+	bool goahead;
+	time_t ats[TZ_MAX_TIMES];
+	unsigned char types[TZ_MAX_TIMES];
+	struct ttinfo ttis[TZ_MAX_TYPES];
+	char chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + CHARS_EXTRA, 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 int_fast32_t
+leapcorr(struct state const *, time_t);
+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 *, struct state *);
+
+#ifdef ALL_STATE
+static struct state *lclptr;
+static struct state *gmtptr;
+#endif /* defined ALL_STATE */
+
+#ifndef ALL_STATE
+static struct state gmtmem;
+#define gmtptr (&gmtmem)
+#endif /* State Farm */
+
+#if 2 <= HAVE_TZNAME + TZ_TIME_T
+char *tzname[2] = { (char *)wildabbr, (char *)wildabbr };
+#endif
+#if 2 <= USG_COMPAT + TZ_TIME_T
+long timezone;
+int daylight;
+#endif
+#if 2 <= ALTZONE + TZ_TIME_T
+long altzone;
+#endif
+
+/* 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;
+}
+
+/* Return true if SP's time type I does not specify local time.  */
+static bool
+ttunspecified(struct state const *sp, int i)
+{
+	char const *abbr = &sp->chars[sp->ttis[i].tt_desigidx];
+	/* memcmp is likely faster than strcmp, and is safe due to CHARS_EXTRA.
+	 */
+	return memcmp(abbr, UNSPEC, sizeof UNSPEC) == 0;
+}
+
+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;
+}
+
+static void
+update_tzname_etc(struct state const *sp, struct ttinfo const *ttisp)
+{
+#if HAVE_TZNAME
+	tzname[ttisp->tt_isdst] = (char *)&sp->chars[ttisp->tt_desigidx];
+#endif
+#if USG_COMPAT
+	if (!ttisp->tt_isdst)
+		timezone = -ttisp->tt_utoff;
+#endif
+#if ALTZONE
+	if (ttisp->tt_isdst)
+		altzone = -ttisp->tt_utoff;
+#endif
+	(void)sp;
+	(void)ttisp;
+}
+
+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';
+	}
+}
+
+/* Input buffer for data read from a compiled tz file.  */
+union input_buffer {
+	/* The first part of the buffer, interpreted as a header.  */
+	struct tzhead tzhead;
+
+	/* The entire buffer.  */
+	char buf[2 * sizeof(struct tzhead) + 2 * sizeof(struct state) +
+		 4 * TZ_MAX_TIMES];
+};
+
+/* TZDIR with a trailing '/' rather than a trailing '\0'.  */
+static char const tzdirslash[sizeof TZDIR] = TZDIR "/";
+
+/* Local storage needed for 'tzloadbody'.  */
+union local_storage {
+	/* The results of analyzing the file's contents after it is opened.  */
+	struct file_analysis {
+		/* The input buffer.  */
+		union input_buffer u;
+
+		/* A temporary state used for parsing a TZ string in the file.
+		 */
+		struct state st;
+	} u;
+
+	/* The file name to be opened.  */
+	char fullname[BIGGEST(sizeof(struct file_analysis),
+			      sizeof tzdirslash + 1024)];
+};
+
+/* Load tz data from the file named NAME into *SP.  Read extended
+   format if DOEXTEND.  Use *LSP for temporary storage.  Return 0 on
+   success, an errno value on failure.  */
+static int
+tzloadbody(char const *name, struct state *sp, bool doextend,
+	   union local_storage *lsp)
+{
+	int i;
+	int fid;
+	int stored;
+	ssize_t nread;
+	bool doaccess;
+	union input_buffer *up = &lsp->u.u;
+	int 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, '.')); 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 < tzheadsize) {
+		int err = nread < 0 ? errno : EINVAL;
+		close(fid);
+		return err;
+	}
+	if (close(fid) < 0)
+		return errno;
+	for (stored = 4; stored <= 8; stored *= 2) {
+		char version = up->tzhead.tzh_version[0];
+		bool skip_datablock = stored == 4 && version;
+		int_fast32_t datablock_size;
+		int_fast32_t ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt);
+		int_fast32_t ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt);
+		int_fast64_t prevtr = -1;
+		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 && 0 <= ttisstdcnt &&
+		      ttisstdcnt < TZ_MAX_TYPES && 0 <= ttisutcnt &&
+		      ttisutcnt < TZ_MAX_TYPES))
+			return EINVAL;
+		datablock_size = (timecnt * stored /* ats */
+				  + timecnt /* types */
+				  + typecnt * 6 /* ttinfos */
+				  + charcnt /* chars */
+				  + leapcnt * (stored + 4) /* lsinfos */
+				  + ttisstdcnt /* ttisstds */
+				  + ttisutcnt); /* ttisuts */
+		if (nread < tzheadsize + datablock_size)
+			return EINVAL;
+		if (skip_datablock)
+			p += datablock_size;
+		else {
+			if (!((ttisstdcnt == typecnt || ttisstdcnt == 0) &&
+			      (ttisutcnt == typecnt || ttisutcnt == 0)))
+				return EINVAL;
+
+			sp->leapcnt = leapcnt;
+			sp->timecnt = timecnt;
+			sp->typecnt = typecnt;
+			sp->charcnt = charcnt;
+
+			/* Read transitions, discarding those out of time_t
+			   range. But pretend the last transition before
+			   TIME_T_MIN occurred at TIME_T_MIN.  */
+			timecnt = 0;
+			for (i = 0; i < sp->timecnt; ++i) {
+				int_fast64_t at = stored == 4 ? detzcode(p)
+							      : detzcode64(p);
+				sp->types[i] = at <= TIME_T_MAX;
+				if (sp->types[i]) {
+					time_t attime =
+						((TYPE_SIGNED(time_t)
+							  ? at < TIME_T_MIN
+							  : at < 0)
+							 ? TIME_T_MIN
+							 : at);
+					if (timecnt &&
+					    attime <= sp->ats[timecnt - 1]) {
+						if (attime <
+						    sp->ats[timecnt - 1])
+							return EINVAL;
+						sp->types[i - 1] = 0;
+						timecnt--;
+					}
+					sp->ats[timecnt++] = attime;
+				}
+				p += stored;
+			}
+
+			timecnt = 0;
+			for (i = 0; i < sp->timecnt; ++i) {
+				unsigned char typ = *p++;
+				if (sp->typecnt <= typ)
+					return EINVAL;
+				if (sp->types[i])
+					sp->types[timecnt++] = typ;
+			}
+			sp->timecnt = timecnt;
+			for (i = 0; i < sp->typecnt; ++i) {
+				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++;
+			/* Ensure '\0'-terminated, and make it safe to call
+			   ttunspecified later.  */
+			memset(&sp->chars[i], 0, CHARS_EXTRA);
+
+			/* 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,
+				   or out of order.  */
+				if (tr <= prevtr)
+					return EINVAL;
+
+				/* To avoid other botches in this code, each
+				   leap second's correction must differ from the
+				   previous one's by 1 second or less, except
+				   that the first correction can be any value;
+				   these requirements are more generous than RFC
+				   8536, to allow future RFC extensions.  */
+				if (!(i == 0 ||
+				      (prevcorr < corr
+					       ? corr == prevcorr + 1
+					       : (corr == prevcorr ||
+						  corr == prevcorr - 1))))
+					return EINVAL;
+				prevtr = tr;
+				prevcorr = corr;
+
+				if (tr <= TIME_T_MAX) {
+					sp->lsis[leapcnt].ls_trans = tr;
+					sp->lsis[leapcnt].ls_corr = 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++;
+				}
+			}
+		}
+
+		nread -= p - up->buf;
+		memmove(up->buf, p, nread);
+
+		/* If this is an old file, we're done.  */
+		if (!version)
+			break;
+	}
+	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, sp)) {
+
+			/* 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)) {
+					int tsabbrlen = strlen(tsabbr);
+					if (j + tsabbrlen < TZ_MAX_CHARS) {
+						strcpy(sp->chars + j, tsabbr);
+						charcnt = 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 &&
+				     sp->timecnt < TZ_MAX_TIMES;
+				     i++) {
+					time_t t = ts->ats[i];
+					if (increment_overflow_time(
+						    &t, leapcorr(sp, t)) ||
+					    (0 < sp->timecnt &&
+					     t <= sp->ats[sp->timecnt - 1]))
+						continue;
+					sp->ats[sp->timecnt] = t;
+					sp->types[sp->timecnt] =
+						(sp->typecnt + ts->types[i]);
+					sp->timecnt++;
+				}
+				for (i = 0; i < ts->typecnt; i++)
+					sp->ttis[sp->typecnt++] = ts->ttis[i];
+			}
+		}
+	}
+	if (sp->typecnt == 0)
+		return EINVAL;
+	if (sp->timecnt > 1) {
+		if (sp->ats[0] <= TIME_T_MAX - SECSPERREPEAT) {
+			time_t repeatat = sp->ats[0] + SECSPERREPEAT;
+			int repeattype = sp->types[0];
+			for (i = 1; i < sp->timecnt; ++i)
+				if (sp->ats[i] == repeatat &&
+				    typesequiv(sp, sp->types[i], repeattype)) {
+					sp->goback = true;
+					break;
+				}
+		}
+		if (TIME_T_MIN + SECSPERREPEAT <= sp->ats[sp->timecnt - 1]) {
+			time_t repeatat =
+				sp->ats[sp->timecnt - 1] - SECSPERREPEAT;
+			int repeattype = sp->types[sp->timecnt - 1];
+			for (i = sp->timecnt - 2; i >= 0; --i)
+				if (sp->ats[i] == repeatat &&
+				    typesequiv(sp, sp->types[i], repeattype)) {
+					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 does not specify local time, or 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 && !ttunspecified(sp, 0) ? -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)
+{
+#ifdef ALL_STATE
+	union local_storage *lsp = malloc(sizeof *lsp);
+	if (!lsp) {
+		return HAVE_MALLOC_ERRNO ? errno : ENOMEM;
+	} else {
+		int err = tzloadbody(name, sp, doextend, lsp);
+		free(lsp);
+		return err;
+	}
+#else
+	union local_storage ls;
+	return tzloadbody(name, sp, doextend, &ls);
+#endif
+}
+
+static bool
+typesequiv(const struct state *sp, int a, int b)
+{
+	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][MONTHSPERYEAR] = {
+	{ 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))
+		return NULL;
+	num = 0;
+	do {
+		num = num * 10 + (c - '0');
+		if (num > max)
+			return NULL; /* illegal value */
+		c = *++strp;
+	} while (is_digit(c));
+	if (num < min)
+		return NULL; /* illegal value */
+	*nump = num;
+	return strp;
+}
+
+/*
+** Given a pointer into a 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;
+	int_fast32_t secsperhour = SECSPERHOUR;
+
+	/*
+	** '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 * 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, MONTHSPERYEAR);
+		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;
+
+	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;
+
+	default:
+		UNREACHABLE();
+	}
+
+	/*
+	** "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, struct state *basep)
+{
+	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;
+	time_t atlo = TIME_T_MIN, leaplo = TIME_T_MIN;
+
+	stdname = name;
+	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;
+	if (basep) {
+		if (0 < basep->timecnt)
+			atlo = basep->ats[basep->timecnt - 1];
+		load_ok = false;
+		sp->leapcnt = basep->leapcnt;
+		memcpy(sp->lsis, basep->lsis, sp->leapcnt * sizeof *sp->lsis);
+	} else {
+		load_ok = tzload(TZDEFRULES, sp, false) == 0;
+		if (!load_ok)
+			sp->leapcnt = 0; /* So, we're off a little.  */
+	}
+	if (0 < sp->leapcnt)
+		leaplo = sp->lsis[sp->leapcnt - 1].ls_trans;
+	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 timecnt;
+			time_t janfirst;
+			int_fast32_t janoffset = 0;
+			int yearbeg, yearlim;
+
+			++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, 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 (atlo < janfirst &&
+				 EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg);
+
+			while (true) {
+				int_fast32_t yearsecs =
+					year_lengths[isleap(yearbeg)] *
+					SECSPERDAY;
+				int yearbeg1 = yearbeg;
+				time_t janfirst1 = janfirst;
+				if (increment_overflow_time(&janfirst1,
+							    yearsecs) ||
+				    increment_overflow(&yearbeg1, 1) ||
+				    atlo <= janfirst1)
+					break;
+				yearbeg = yearbeg1;
+				janfirst = janfirst1;
+			}
+
+			yearlim = yearbeg;
+			if (increment_overflow(&yearlim, YEARSPERREPEAT + 1))
+				yearlim = INT_MAX;
+			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)) {
+					if (TZ_MAX_TIMES - 2 < timecnt)
+						break;
+					sp->ats[timecnt] = janfirst;
+					if (!increment_overflow_time(
+						    &sp->ats[timecnt],
+						    janoffset + starttime) &&
+					    atlo <= sp->ats[timecnt])
+						sp->types[timecnt++] =
+							!reversed;
+					sp->ats[timecnt] = janfirst;
+					if (!increment_overflow_time(
+						    &sp->ats[timecnt],
+						    janoffset + endtime) &&
+					    atlo <= sp->ats[timecnt]) {
+						sp->types[timecnt++] = reversed;
+					}
+				}
+				if (endtime < leaplo) {
+					yearlim = year;
+					if (increment_overflow(&yearlim,
+							       YEARSPERREPEAT +
+								       1))
+						yearlim = INT_MAX;
+				}
+				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;
+			/*
+			** 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] += dstoffset -
+							theirdstoffset;
+					} else {
+						sp->ats[i] += stdoffset -
+							theirstdoffset;
+					}
+				}
+				theiroffset = -sp->ttis[j].tt_utoff;
+				if (sp->ttis[j].tt_isdst)
+					theirdstoffset = theiroffset;
+				else
+					theirstdoffset = theiroffset;
+			}
+			/*
+			** Finally, fill in ttis.
+			*/
+			init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+			init_ttinfo(&sp->ttis[1], -dstoffset, true, stdlen + 1);
+			sp->typecnt = 2;
+			sp->defaulttype = 0;
+		}
+	} else {
+		dstlen = 0;
+		sp->typecnt = 1; /* only standard time */
+		sp->timecnt = 0;
+		init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
+		sp->defaulttype = 0;
+	}
+	sp->charcnt = charcnt;
+	cp = sp->chars;
+	memcpy(cp, stdname, stdlen);
+	cp += stdlen;
+	*cp++ = '\0';
+	if (dstlen != 0) {
+		memcpy(cp, dstname, dstlen);
+		*(cp + dstlen) = '\0';
+	}
+	return true;
+}
+
+/* Initialize *SP to a value appropriate for the TZ setting NAME.
+   Return 0 on success, an errno value on failure.  */
+static int
+zoneinit(struct state *sp, char const *name)
+{
+	if (name && !name[0]) {
+		/*
+		** User wants it fast rather than right.
+		*/
+		sp->leapcnt = 0; /* so, we're off a little */
+		sp->timecnt = 0;
+		sp->typecnt = 0;
+		sp->charcnt = 0;
+		sp->goback = sp->goahead = false;
+		init_ttinfo(&sp->ttis[0], 0, false, 0);
+		strcpy(sp->chars, gmt);
+		sp->defaulttype = 0;
+		return 0;
+	} else {
+		int err = tzload(name, sp, true);
+		if (err != 0 && name && name[0] != ':' &&
+		    tzparse(name, sp, NULL))
+			err = 0;
+		if (err == 0)
+			scrub_abbrs(sp);
+		return err;
+	}
+}
+
+#if NETBSD_INSPIRED
+
+timezone_t
+tzalloc(char const *name)
+{
+	timezone_t sp = malloc(sizeof *sp);
+	if (sp) {
+		int err = zoneinit(sp, name);
+		if (err != 0) {
+			free(sp);
+			errno = err;
+			return NULL;
+		}
+	} else if (!HAVE_MALLOC_ERRNO)
+		errno = ENOMEM;
+	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;
+		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;
+
+		/* Beware integer overflow, as SECONDS might
+		   be close to the maximum time_t.  */
+		years = seconds / SECSPERREPEAT * YEARSPERREPEAT;
+		seconds = years * AVGSECSPERYEAR;
+		years += YEARSPERREPEAT;
+		if (t < sp->ats[0])
+			newt = t + seconds + SECSPERREPEAT;
+		else
+			newt = t - seconds - SECSPERREPEAT;
+
+		if (newt < sp->ats[0] || newt > sp->ats[sp->timecnt - 1])
+			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))
+				return NULL;
+			result->tm_year = 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) >> 1;
+
+			if (t < sp->ats[mid])
+				hi = mid;
+			else
+				lo = mid + 1;
+		}
+		i = 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 = (char *)&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(struct state *sp, time_t const *timep, struct tm *tmp)
+{
+	return localsub(sp, timep, 0, tmp);
+}
+
+#endif
+
+/*
+** gmtsub is to gmtime as localsub is to localtime.
+*/
+
+static struct tm *
+gmtsub(struct state const *sp, time_t const *timep, int_fast32_t offset,
+       struct tm *tmp)
+{
+	struct tm *result;
+
+	result = timesub(timep, offset, gmtptr, tmp);
+#ifdef TM_ZONE
+	/*
+	** Could get fancy here and deliver something such as
+	** "+xx" or "-xx" if offset is non-zero,
+	** but this is no time for a treasure hunt.
+	*/
+	tmp->TM_ZONE = ((char *)(offset	? wildabbr : gmtptr->chars));
+#endif /* defined TM_ZONE */
+	(void)sp;
+	return result;
+}
+
+#ifdef STD_INSPIRED
+
+struct tm *
+offtime(const time_t *timep, long offset)
+{
+	gmtcheck();
+	return gmtsub(gmtptr, timep, offset, &tm);
+}
+
+#endif /* defined STD_INSPIRED */
+
+/*
+** Return the number of leap years through the end of the given year
+** where, to make the math easy, the answer for year zero is defined as zero.
+*/
+
+static time_t
+leaps_thru_end_of_nonneg(time_t y)
+{
+	return y / 4 - y / 100 + y / 400;
+}
+
+static time_t
+leaps_thru_end_of(time_t 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;
+	const int *ip;
+	int_fast32_t corr;
+	int i;
+	int_fast32_t idays, rem, dayoff, dayrem;
+	time_t y;
+
+	/* If less than SECSPERMIN, the number of seconds since the
+	   most recent positive leap second; otherwise, do not add 1
+	   to localtime tm_sec because of leap seconds.  */
+	time_t secs_since_posleap = SECSPERMIN;
+
+	corr = 0;
+	i = (sp == NULL) ? 0 : sp->leapcnt;
+	while (--i >= 0) {
+		lp = &sp->lsis[i];
+		if (*timep >= lp->ls_trans) {
+			corr = lp->ls_corr;
+			if ((i == 0 ? 0 : lp[-1].ls_corr) < corr)
+				secs_since_posleap = *timep - lp->ls_trans;
+			break;
+		}
+	}
+
+	/* Calculate the year, avoiding integer overflow even if
+	   time_t is unsigned.  */
+	tdays = *timep / SECSPERDAY;
+	rem = *timep % SECSPERDAY;
+	rem += offset % SECSPERDAY - corr % SECSPERDAY + 3 * SECSPERDAY;
+	dayoff = offset / SECSPERDAY - corr / SECSPERDAY + rem / SECSPERDAY - 3;
+	rem %= SECSPERDAY;
+	/* y = (EPOCH_YEAR
+		+ floor((tdays + dayoff) / DAYSPERREPEAT) * YEARSPERREPEAT),
+	   sans overflow.  But calculate against 1570 (EPOCH_YEAR -
+	   YEARSPERREPEAT) instead of against 1970 so that things work
+	   for localtime values before 1970 when time_t is unsigned.  */
+	dayrem = tdays % DAYSPERREPEAT;
+	dayrem += dayoff % DAYSPERREPEAT;
+	y = (EPOCH_YEAR - YEARSPERREPEAT +
+	     ((1 + dayoff / DAYSPERREPEAT + dayrem / DAYSPERREPEAT -
+	       ((dayrem % DAYSPERREPEAT) < 0) + tdays / DAYSPERREPEAT) *
+	      YEARSPERREPEAT));
+	/* idays = (tdays + dayoff) mod DAYSPERREPEAT, sans overflow.  */
+	idays = tdays % DAYSPERREPEAT;
+	idays += dayoff % DAYSPERREPEAT + 2 * DAYSPERREPEAT;
+	idays %= DAYSPERREPEAT;
+	/* Increase Y and decrease IDAYS until IDAYS is in range for Y.  */
+	while (year_lengths[isleap(y)] <= idays) {
+		int tdelta = idays / DAYSPERLYEAR;
+		int_fast32_t ydelta = tdelta + !tdelta;
+		time_t newy = y + ydelta;
+		int leapdays;
+		leapdays =
+			leaps_thru_end_of(newy - 1) - leaps_thru_end_of(y - 1);
+		idays -= ydelta * DAYSPERNYEAR;
+		idays -= leapdays;
+		y = newy;
+	}
+
+	if (!TYPE_SIGNED(time_t) && y < TM_YEAR_BASE) {
+		int signed_y = y;
+		tmp->tm_year = signed_y - TM_YEAR_BASE;
+	} else if ((!TYPE_SIGNED(time_t) || INT_MIN + TM_YEAR_BASE <= y) &&
+		   y - TM_YEAR_BASE <= INT_MAX)
+		tmp->tm_year = y - TM_YEAR_BASE;
+	else {
+		errno = EOVERFLOW;
+		return NULL;
+	}
+	tmp->tm_yday = idays;
+	/*
+	** The "extra" mods below avoid overflow problems.
+	*/
+	tmp->tm_wday =
+		(TM_WDAY_BASE +
+		 ((tmp->tm_year % DAYSPERWEEK) * (DAYSPERNYEAR % DAYSPERWEEK)) +
+		 leaps_thru_end_of(y - 1) -
+		 leaps_thru_end_of(TM_YEAR_BASE - 1) + idays);
+	tmp->tm_wday %= DAYSPERWEEK;
+	if (tmp->tm_wday < 0)
+		tmp->tm_wday += DAYSPERWEEK;
+	tmp->tm_hour = rem / SECSPERHOUR;
+	rem %= SECSPERHOUR;
+	tmp->tm_min = rem / SECSPERMIN;
+	tmp->tm_sec = rem % SECSPERMIN;
+
+	/* Use "... ??:??:60" at the end of the localtime minute containing
+	   the second just before the positive leap second.  */
+	tmp->tm_sec += secs_since_posleap <= tmp->tm_sec;
+
+	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 = idays + 1;
+	tmp->tm_isdst = 0;
+#ifdef TM_GMTOFF
+	tmp->TM_GMTOFF = offset;
+#endif /* defined TM_GMTOFF */
+	return tmp;
+}
+
+char *
+ctime(const time_t *timep)
+{
+	/*
+	** Section 4.12.3.2 of X3.159-1989 requires that
+	**	The ctime function converts the calendar time pointed to by
+	*timer *	to local time in the form of a string. It is equivalent
+	*to *		asctime(localtime(timer))
+	*/
+	struct tm *tmp = localtime(timep);
+	return tmp ? asctime(tmp) : NULL;
+}
+
+char *
+ctime_r(const time_t *timep, char *buf)
+{
+	struct tm mytm;
+	struct tm *tmp = localtime_r(timep, &mytm);
+	return tmp ? asctime_r(tmp, buf) : NULL;
+}
+
+/*
+** Adapted from code provided by Robert Elz, who writes:
+**	The "best" way to do mktime I think is based on an idea of Bob
+**	Kridle's (so its said...) from a long time ago.
+**	It does a binary search of the time_t space. Since time_t's are
+**	just 32 bits, its a max of 32 iterations (even at 64 bits it
+**	would still be very reasonable).
+*/
+
+#ifndef WRONG
+#define WRONG (-1)
+#endif /* !defined WRONG */
+
+/*
+** Normalize logic courtesy Paul Eggert.
+*/
+
+static bool
+increment_overflow(int *ip, int j)
+{
+	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_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;
+}
+
+#ifdef STD_INSPIRED
+
+time_t
+timelocal(struct tm *tmp)
+{
+	if (tmp != NULL)
+		tmp->tm_isdst = -1; /* in case it wasn't initialized */
+	return mktime(tmp);
+}
+
+time_t
+timegm(struct tm *tmp)
+{
+	return timeoff(tmp, 0);
+}
+
+time_t
+timeoff(struct tm *tmp, long offset)
+{
+	if (tmp)
+		tmp->tm_isdst = 0;
+	gmtcheck();
+	return time1(tmp, gmtsub, gmtptr, offset);
+}
+
+#endif /* defined STD_INSPIRED */
+
+static int_fast32_t
+leapcorr(struct state const *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;
+}
+
+#if TZ_TIME_T
+
+#if !USG_COMPAT
+#define daylight 0
+#define timezone 0
+#endif
+#if !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
diff --git a/src/lib/tzcode/private.h b/src/lib/tzcode/private.h
index 6859fc752f..1b1ff7e7d1 100644
--- a/src/lib/tzcode/private.h
+++ b/src/lib/tzcode/private.h
@@ -16,11 +16,37 @@
 ** Thank you!
 */
 
+/* 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'.
 */
 
+#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_MALLOC_ERRNO
+#define HAVE_MALLOC_ERRNO 1
+#endif
+
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
+
 /* Enable tm_gmtoff, tm_zone, and environ on GNUish systems.  */
 #define _GNU_SOURCE 1
 
@@ -45,6 +71,140 @@
 
 #include <inttypes.h>
 #include <stdint.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+#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
+
+/*
+** 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 defined LOCALTIME_IMPLEMENTATION && TZ_TIME_T
+static time_t sys_time(time_t *x) { return time(x); }
+#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 2 <= HAVE_TZNAME + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern char *tzname[];
+#endif
+#if 2 <= USG_COMPAT + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern long timezone;
+extern int daylight;
+#endif
+#if 2 <= ALTZONE + (TZ_TIME_T || !HAVE_POSIX_DECLS)
+extern long altzone;
+#endif
+
+#ifdef STD_INSPIRED
+# 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.
+*/
+#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, time_t) ATTRIBUTE_PURE;
+#  endif
+#  if TZ_TIME_T || !defined time2posix_z
+time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_PURE;
+#  endif
+# endif
+#endif
 
 /*
 ** Finally, some convenience items.
@@ -54,6 +214,43 @@
 #define TYPE_SIGNED(type) (((type)-1) < 0)
 #define TWOS_COMPLEMENT(t) ((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)						\
+  ((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 problems 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;
@@ -64,6 +261,39 @@
 	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
 	1 + TYPE_SIGNED(type))
 
+/*
+** INITIALIZE(x)
+*/
+
+#ifdef GCC_LINT
+# define INITIALIZE(x)	((x) = 0)
+#else
+# define INITIALIZE(x)
+#endif
+
+/* Whether memory access must strictly follow the C standard.
+   If 0, it's OK to read uninitialized storage so long as the value is
+   not relied upon.  Defining it to 0 lets mktime access parts of
+   struct tm that might be uninitialized, as a heuristic when the
+   standard doesn't say what to return and when tm_gmtoff can help
+   mktime likely infer a better value.  */
+#ifndef UNINIT_TRAP
+# define UNINIT_TRAP 0
+#endif
+
+#ifdef DEBUG
+# define UNREACHABLE() abort()
+#elif 4 < __GNUC__ + (5 <= __GNUC_MINOR__)
+# define UNREACHABLE() __builtin_unreachable()
+#elif defined __has_builtin
+# if __has_builtin(__builtin_unreachable)
+#  define UNREACHABLE() __builtin_unreachable()
+# endif
+#endif
+#ifndef UNREACHABLE
+# define UNREACHABLE() ((void) 0)
+#endif
+
 /* Handy macros that are independent of tzfile implementation.  */
 
 #define YEARSPERREPEAT 400 /* years before a Gregorian repeat */
@@ -77,6 +307,12 @@
 #define SECSPERHOUR    (SECSPERMIN * MINSPERHOUR)
 #define SECSPERDAY     ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
 #define MONTHSPERYEAR  12
+
+#define YEARSPERREPEAT		400	/* years before a Gregorian repeat */
+#define DAYSPERREPEAT		((int_fast32_t) 400 * 365 + 100 - 4 + 1)
+#define SECSPERREPEAT		((int_fast64_t) DAYSPERREPEAT * SECSPERDAY)
+#define AVGSECSPERYEAR		(SECSPERREPEAT / YEARSPERREPEAT)
+
 #define TM_SUNDAY      0
 #define TM_MONDAY      1
 #define TM_TUESDAY     2
@@ -96,7 +332,10 @@
 #define TM_OCTOBER     9
 #define TM_NOVEMBER    10
 #define TM_DECEMBER    11
-#define TM_YEAR_BASE   1900
+
+#define TM_YEAR_BASE	1900
+#define TM_WDAY_BASE	TM_MONDAY
+
 #define EPOCH_YEAR     1970
 #define EPOCH_WDAY     TM_THURSDAY
 
diff --git a/src/lib/tzcode/tzfile.h b/src/lib/tzcode/tzfile.h
new file mode 100644
index 0000000000..c3b1c39616
--- /dev/null
+++ b/src/lib/tzcode/tzfile.h
@@ -0,0 +1,122 @@
+/* Layout and location of TZif files.  */
+
+#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
+#define TZDIR "/usr/share/zoneinfo" /* Time zone object file directory */
+#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'-'4' as of 2021 */
+	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 */
+
+#endif /* !defined TZFILE_H */
-- 
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