Update timezone code from tzcode 2017b.

This patch updates files coming from tzcode to the versions in tzcode
2017b.  A couple of changes to other glibc code are needed.
time/tzset.c was using the SECSPERDAY macro from tzfile.h, which no
longer defines that macro, so a local definition is added to tzset.c.
Because timezone/private.h now defines the _ macro whenever
HAVE_GETTEXT is true, even if it was previously defined, it is also
necessary to avoid a conflict with the definition in
include/libintl.h.  Defining _ISOMAC is the obvious way to avoid such
internal definitions being visible, together with defining TZ_DOMAIN
so that zic and zdump continue to get the messages from the libc
domain as desired.  However, zic and zdump rely on PKGVERSION and
REPORT_BUGS_TO from config.h, which is not included by default with
_ISOMAC, so -include config.h needs adding to the options for these
programs as well.  Together those changes allow unmodified tzcode
2017b sources to work in glibc.

Tested for x86_64.

	* timezone/private.h: Update from tzcode 2017b.
	* timezone/tzfile.h: Likewise.
	* timezone/tzselect.ksh: Likewise.
	* timezone/zdump.c: Likewise.
	* timezone/zic.c: Likewise.
	* timezone/Makefile (tz-cflags): Add -D_ISOMAC
	-DTZ_DOMAIN='"libc"' -include $(common-objpfx)config.h.
	* time/tzset.c (SECSPERDAY): New macro.

6 files changed, 864 insertions, 615 deletions

diff --git a/timezone/Makefile b/timezone/Makefile
index 35e6a95e6b..d6cc7ba357 100644
--- a/timezone/Makefile
+++ b/timezone/Makefile
@@ -59,7 +59,8 @@ tz-cflags = -DTZDIR='"$(zonedir)"' \
 	    -DTZDEFAULT='"$(localtime-file)"' \
 	    -DTZDEFRULES='"$(posixrules-file)"' \
 	    -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone \
-	    -DHAVE_GETTEXT -DUSE_LTZ=0 -Wno-maybe-uninitialized
+	    -DHAVE_GETTEXT -DUSE_LTZ=0 -D_ISOMAC -DTZ_DOMAIN='"libc"' \
+	    -include $(common-objpfx)config.h -Wno-maybe-uninitialized
 
 # The -Wno-unused-variable flag is used to prevent GCC 6
 # from warning about time_t_min and time_t_max which are
diff --git a/timezone/private.h b/timezone/private.h
index 1c176e62bc..e2f23f5f40 100644
--- a/timezone/private.h
+++ b/timezone/private.h
@@ -15,6 +15,7 @@
 ** Thank you!
 */
 
+/* This string was in the Factory zone through version 2016f.  */
 #define GRANDPARENTED	"Local time zone must be set--see zic manual page"
 
 /*
@@ -22,6 +23,10 @@
 ** 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
+
 #ifndef HAVE_GETTEXT
 #define HAVE_GETTEXT		0
 #endif /* !defined HAVE_GETTEXT */
@@ -34,6 +39,10 @@
 #define HAVE_LINK		1
 #endif /* !defined HAVE_LINK */
 
+#ifndef HAVE_POSIX_DECLS
+#define HAVE_POSIX_DECLS 1
+#endif
+
 #ifndef HAVE_STRDUP
 #define HAVE_STRDUP 1
 #endif
@@ -69,9 +78,9 @@
 
 /* Enable tm_gmtoff and tm_zone on GNUish systems.  */
 #define _GNU_SOURCE 1
-/* Fix asctime_r on Solaris 10.  */
+/* Fix asctime_r on Solaris 11.  */
 #define _POSIX_PTHREAD_SEMANTICS 1
-/* Enable strtoimax on Solaris 10.  */
+/* Enable strtoimax on pre-C99 Solaris 11.  */
 #define __EXTENSIONS__ 1
 
 /*
@@ -95,23 +104,26 @@
 #undef tzalloc
 #undef tzfree
 
-#include "sys/types.h"	/* for time_t */
-#include "stdio.h"
-#include "string.h"
-#include "limits.h"	/* for CHAR_BIT et al. */
-#include "stdlib.h"
+#include <sys/types.h>	/* for time_t */
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>	/* for CHAR_BIT et al. */
+#include <stdlib.h>
 
-#include "errno.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"
+#include <libintl.h>
 #endif /* HAVE_GETTEXT */
 
 #if HAVE_SYS_WAIT_H
@@ -126,7 +138,7 @@
 #endif /* !defined WEXITSTATUS */
 
 #if HAVE_UNISTD_H
-#include "unistd.h"	/* for F_OK, R_OK, and other POSIX goodness */
+#include <unistd.h>	/* for F_OK, R_OK, and other POSIX goodness */
 #endif /* HAVE_UNISTD_H */
 
 #ifndef HAVE_STRFTIME_L
@@ -149,19 +161,19 @@
 
 /*
 ** Define HAVE_STDINT_H's default value here, rather than at the
-** start, since __GLIBC__'s value depends on previously-included
-** files.
-** (glibc 2.1 and later have stdint.h, even with pre-C99 compilers.)
+** 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__)
+    || __CYGWIN__ || INTMAX_MAX)
 #endif /* !defined HAVE_STDINT_H */
 
 #if HAVE_STDINT_H
-#include "stdint.h"
+#include <stdint.h>
 #endif /* !HAVE_STDINT_H */
 
 #ifndef HAVE_INTTYPES_H
@@ -197,14 +209,18 @@ typedef long		int_fast64_t;
 # endif
 #endif
 
-#ifndef SCNdFAST64
+#ifndef PRIdFAST64
 # if INT_FAST64_MAX == LLONG_MAX
-#  define SCNdFAST64 "lld"
+#  define PRIdFAST64 "lld"
 # else
-#  define SCNdFAST64 "ld"
+#  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;
@@ -304,6 +320,13 @@ typedef unsigned long uintmax_t;
 ** Workarounds for compilers/systems.
 */
 
+#ifndef EPOCH_LOCAL
+# define EPOCH_LOCAL 0
+#endif
+#ifndef EPOCH_OFFSET
+# define EPOCH_OFFSET 0
+#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.
@@ -311,7 +334,7 @@ typedef unsigned long uintmax_t;
 ** (e.g., time_t wider than 'long', or unsigned time_t) even on
 ** typical platforms.
 */
-#ifdef time_tz
+#if defined time_tz || EPOCH_LOCAL || EPOCH_OFFSET != 0
 # ifdef LOCALTIME_IMPLEMENTATION
 static time_t sys_time(time_t *x) { return time(x); }
 # endif
@@ -379,25 +402,21 @@ time_t time(time_t *);
 void tzset(void);
 #endif
 
-/*
-** Some time.h implementations don't declare asctime_r.
-** Others might define it as a macro.
-** Fix the former without affecting the latter.
-** Similarly for timezone, daylight, and altzone.
-*/
-
-#ifndef asctime_r
-extern char *	asctime_r(struct tm const *restrict, char *restrict);
+#if !HAVE_DECL_ASCTIME_R && !defined asctime_r
+extern char *asctime_r(struct tm const *restrict, char *restrict);
 #endif
 
-#ifdef USG_COMPAT
-# ifndef timezone
+#if !HAVE_POSIX_DECLS
+# ifdef USG_COMPAT
+#  ifndef timezone
 extern long timezone;
-# endif
-# ifndef daylight
+#  endif
+#  ifndef daylight
 extern int daylight;
+#  endif
 # endif
 #endif
+
 #if defined ALTZONE && !defined altzone
 extern long altzone;
 #endif
@@ -481,14 +500,8 @@ time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_PURE;
 # include <stdbool.h>
 #endif
 
-#ifndef TYPE_BIT
 #define TYPE_BIT(type)	(sizeof (type) * CHAR_BIT)
-#endif /* !defined TYPE_BIT */
-
-#ifndef TYPE_SIGNED
 #define TYPE_SIGNED(type) (((type) -1) < 0)
-#endif /* !defined TYPE_SIGNED */
-
 #define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0)
 
 /* Max and min values of the integer type T, of which only the bottom
@@ -500,11 +513,29 @@ time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_PURE;
 #define MINVAL(t, b)						\
   ((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
 
-/* The minimum and maximum finite time values.  This assumes no padding.  */
+/* The minimum and maximum finite time values.  This implementation
+   assumes no padding if time_t is signed and either the compiler is
+   pre-C11 or time_t is not one of the standard signed integer types.  */
+#if 201112 <= __STDC_VERSION__
+static time_t const time_t_min
+  = (TYPE_SIGNED(time_t)
+     ? _Generic((time_t) 0,
+		signed char: SCHAR_MIN, short: SHRT_MIN,
+		int: INT_MIN, long: LONG_MIN, long long: LLONG_MIN,
+		default: MINVAL(time_t, TYPE_BIT(time_t)))
+     : 0);
+static time_t const 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: MAXVAL(time_t, TYPE_BIT(time_t)))
+     : -1);
+#else
 static time_t const time_t_min = MINVAL(time_t, TYPE_BIT(time_t));
 static time_t const time_t_max = MAXVAL(time_t, TYPE_BIT(time_t));
+#endif
 
-#ifndef INT_STRLEN_MAXIMUM
 /*
 ** 302 / 1000 is log10(2.0) rounded up.
 ** Subtract one for the sign bit if the type is signed;
@@ -514,7 +545,6 @@ static time_t const time_t_max = MAXVAL(time_t, TYPE_BIT(time_t));
 #define INT_STRLEN_MAXIMUM(type) \
 	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
 	1 + TYPE_SIGNED(type))
-#endif /* !defined INT_STRLEN_MAXIMUM */
 
 /*
 ** INITIALIZE(x)
@@ -536,13 +566,11 @@ static time_t const time_t_max = MAXVAL(time_t, TYPE_BIT(time_t));
 ** The default is to use gettext if available, and use MSGID otherwise.
 */
 
-#ifndef _
 #if HAVE_GETTEXT
 #define _(msgid) gettext(msgid)
 #else /* !HAVE_GETTEXT */
 #define _(msgid) msgid
 #endif /* !HAVE_GETTEXT */
-#endif /* !defined _ */
 
 #if !defined TZ_DOMAIN && defined HAVE_GETTEXT
 # define TZ_DOMAIN "tz"
@@ -555,24 +583,70 @@ char *asctime_r(struct tm const *, char *);
 char *ctime_r(time_t const *, char *);
 #endif /* HAVE_INCOMPATIBLE_CTIME_R */
 
-#ifndef YEARSPERREPEAT
+/* Handy macros that are independent of tzfile implementation.  */
+
 #define YEARSPERREPEAT		400	/* years before a Gregorian repeat */
-#endif /* !defined YEARSPERREPEAT */
+
+#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))
 
 /*
-** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
+** 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.
 */
 
-#ifndef AVGSECSPERYEAR
-#define AVGSECSPERYEAR		31556952L
-#endif /* !defined AVGSECSPERYEAR */
+#define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
+
 
-#ifndef SECSPERREPEAT
-#define SECSPERREPEAT		((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
-#endif /* !defined SECSPERREPEAT */
+/*
+** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
+*/
 
-#ifndef SECSPERREPEAT_BITS
+#define AVGSECSPERYEAR		31556952L
+#define SECSPERREPEAT \
+  ((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
 #define SECSPERREPEAT_BITS	34	/* ceil(log2(SECSPERREPEAT)) */
-#endif /* !defined SECSPERREPEAT_BITS */
 
 #endif /* !defined PRIVATE_H */
diff --git a/timezone/tzfile.h b/timezone/tzfile.h
index ebecd68322..0e51dce1d7 100644
--- a/timezone/tzfile.h
+++ b/timezone/tzfile.h
@@ -114,56 +114,4 @@ struct tzhead {
 #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 */
diff --git a/timezone/tzselect.ksh b/timezone/tzselect.ksh
index 2c3b2f4438..d2c3a6d1dd 100755
--- a/timezone/tzselect.ksh
+++ b/timezone/tzselect.ksh
@@ -7,7 +7,7 @@ REPORT_BUGS_TO=tz@iana.org
 # Ask the user about the time zone, and output the resulting TZ value to stdout.
 # Interact with the user via stderr and stdin.
 
-# Contributed by Paul Eggert.
+# Contributed by Paul Eggert.  This file is in the public domain.
 
 # Porting notes:
 #
@@ -346,11 +346,14 @@ while
 				'that is 10 hours ahead (east) of UTC.'
 			read TZ
 			$AWK -v TZ="$TZ" 'BEGIN {
-				tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
-				time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
+				tzname = "(<[[:alnum:]+-]{3,}>|[[:alpha:]]{3,})"
+				time = "(2[0-4]|[0-1]?[0-9])" \
+				  "(:[0-5][0-9](:[0-5][0-9])?)?"
 				offset = "[-+]?" time
-				date = "(J?[0-9]+|M[0-9]+\\.[0-9]+\\.[0-9]+)"
-				datetime = "," date "(/" time ")?"
+				mdate = "M([1-9]|1[0-2])\\.[1-5]\\.[0-6]"
+				jdate = "((J[1-9]|[0-9]|J?[1-9][0-9]" \
+				  "|J?[1-2][0-9][0-9])|J?3[0-5][0-9]|J?36[0-5])"
+				datetime = ",(" mdate "|" jdate ")(/" time ")?"
 				tzpattern = "^(:.*|" tzname offset "(" tzname \
 				  "(" offset ")?(" datetime datetime ")?)?)$"
 				if (TZ ~ tzpattern) exit 1
@@ -509,7 +512,7 @@ while
 		case $TZsec in
 		$UTsec)
 			extra_info="
-Local time is now:	$TZdate.
+Selected time is now:	$TZdate.
 Universal Time is now:	$UTdate."
 			break
 		esac
@@ -545,7 +548,7 @@ case $SHELL in
 *) file=.profile line="TZ='$TZ'; export TZ"
 esac
 
-say >&2 "
+test -t 1 && say >&2 "
 You can make this change permanent for yourself by appending the line
 	$line
 to the file '$file' in your home directory; then log out and log in again.
diff --git a/timezone/zdump.c b/timezone/zdump.c
index 063a2635ec..bf75800101 100644
--- a/timezone/zdump.c
+++ b/timezone/zdump.c
@@ -19,89 +19,7 @@
 # define USE_LTZ 1
 #endif
 
-#if USE_LTZ
-# include "private.h"
-#endif
-
-/* Enable tm_gmtoff and tm_zone on GNUish systems.  */
-#define _GNU_SOURCE 1
-/* Enable strtoimax on Solaris 10.  */
-#define __EXTENSIONS__ 1
-
-#include "stdio.h"	/* for stdout, stderr, perror */
-#include "string.h"	/* for strcpy */
-#include "sys/types.h"	/* for time_t */
-#include "time.h"	/* for struct tm */
-#include "stdlib.h"	/* for exit, malloc, atoi */
-#include "limits.h"	/* for CHAR_BIT, LLONG_MAX */
-#include <errno.h>
-
-/*
-** Substitutes for pre-C99 compilers.
-** Much of this section of code is stolen from private.h.
-*/
-
-#ifndef HAVE_STDINT_H
-# define HAVE_STDINT_H \
-    (199901 <= __STDC_VERSION__ \
-     || 2 < __GLIBC__ + (1 <= __GLIBC_MINOR__)	\
-     || __CYGWIN__)
-#endif
-#if HAVE_STDINT_H
-# include "stdint.h"
-#endif
-#ifndef HAVE_INTTYPES_H
-# define HAVE_INTTYPES_H HAVE_STDINT_H
-#endif
-#if HAVE_INTTYPES_H
-# include <inttypes.h>
-#endif
-
-#ifndef INT_FAST32_MAX
-# if INT_MAX >> 31 == 0
-typedef long int_fast32_t;
-# else
-typedef int int_fast32_t;
-# endif
-#endif
-
-/* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
-#if !defined LLONG_MAX && defined __LONG_LONG_MAX__
-# define LLONG_MAX __LONG_LONG_MAX__
-#endif
-
-#ifndef INTMAX_MAX
-# ifdef LLONG_MAX
-typedef long long intmax_t;
-#  define strtoimax strtoll
-#  define INTMAX_MAX LLONG_MAX
-# else
-typedef long intmax_t;
-#  define strtoimax strtol
-#  define INTMAX_MAX LONG_MAX
-# endif
-#endif
-
-#ifndef PRIdMAX
-# if INTMAX_MAX == LLONG_MAX
-#  define PRIdMAX "lld"
-# else
-#  define PRIdMAX "ld"
-# 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
+#include "private.h"
 
 #ifndef HAVE_LOCALTIME_R
 # define HAVE_LOCALTIME_R 1
@@ -131,62 +49,6 @@ typedef long intmax_t;
 #define MAX_STRING_LENGTH	1024
 #endif /* !defined MAX_STRING_LENGTH */
 
-#if __STDC_VERSION__ < 199901
-# define true 1
-# define false 0
-# define bool int
-#else
-# include <stdbool.h>
-#endif
-
-#ifndef EXIT_SUCCESS
-#define EXIT_SUCCESS	0
-#endif /* !defined EXIT_SUCCESS */
-
-#ifndef EXIT_FAILURE
-#define EXIT_FAILURE	1
-#endif /* !defined EXIT_FAILURE */
-
-#ifndef SECSPERMIN
-#define SECSPERMIN	60
-#endif /* !defined SECSPERMIN */
-
-#ifndef MINSPERHOUR
-#define MINSPERHOUR	60
-#endif /* !defined MINSPERHOUR */
-
-#ifndef SECSPERHOUR
-#define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
-#endif /* !defined SECSPERHOUR */
-
-#ifndef HOURSPERDAY
-#define HOURSPERDAY	24
-#endif /* !defined HOURSPERDAY */
-
-#ifndef EPOCH_YEAR
-#define EPOCH_YEAR	1970
-#endif /* !defined EPOCH_YEAR */
-
-#ifndef TM_YEAR_BASE
-#define TM_YEAR_BASE	1900
-#endif /* !defined TM_YEAR_BASE */
-
-#ifndef DAYSPERNYEAR
-#define DAYSPERNYEAR	365
-#endif /* !defined DAYSPERNYEAR */
-
-#ifndef isleap
-#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
-#endif /* !defined isleap */
-
-#ifndef isleap_sum
-/*
-** See tzfile.h for details on isleap_sum.
-*/
-#define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
-#endif /* !defined isleap_sum */
-
-#define SECSPERDAY	((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
 #define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
 #define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
 #define SECSPER400YEARS	(SECSPERNYEAR * (intmax_t) (300 + 3)	\
@@ -201,49 +63,24 @@ typedef long intmax_t;
 */
 enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
 
-#ifndef HAVE_GETTEXT
-#define HAVE_GETTEXT 0
-#endif
 #if HAVE_GETTEXT
-#include "locale.h"	/* for setlocale */
-#include "libintl.h"
+#include <locale.h>	/* for setlocale */
 #endif /* HAVE_GETTEXT */
 
-#if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
-# define ATTRIBUTE_PURE __attribute__ ((__pure__))
-#else
-# define ATTRIBUTE_PURE /* empty */
-#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.
-*/
-
-#ifndef _
-#if HAVE_GETTEXT
-#define _(msgid) gettext(msgid)
-#else /* !HAVE_GETTEXT */
-#define _(msgid) msgid
-#endif /* !HAVE_GETTEXT */
-#endif /* !defined _ */
-
-#if !defined TZ_DOMAIN && defined HAVE_GETTEXT
-# define TZ_DOMAIN "tz"
-#endif
-
 #if ! HAVE_LOCALTIME_RZ
 # undef  timezone_t
 # define timezone_t char **
 #endif
 
 extern char **	environ;
+
+#if !HAVE_POSIX_DECLS
 extern int	getopt(int argc, char * const argv[],
 			const char * options);
 extern char *	optarg;
 extern int	optind;
-extern char *	tzname[2];
+extern char *	tzname[];
+#endif
 
 /* The minimum and maximum finite time values.  */
 enum { atime_shift = CHAR_BIT * sizeof (time_t) - 2 };
@@ -266,6 +103,8 @@ static intmax_t	delta(struct tm *, struct tm *) ATTRIBUTE_PURE;
 static void dumptime(struct tm const *);
 static time_t hunt(timezone_t, char *, time_t, time_t);
 static void show(timezone_t, char *, time_t, bool);
+static void showtrans(char const *, struct tm const *, time_t, char const *,
+		      char const *);
 static const char *tformat(void);
 static time_t yeartot(intmax_t) ATTRIBUTE_PURE;
 
@@ -303,6 +142,19 @@ sumsize(size_t a, size_t b)
   return sum;
 }
 
+/* Return a pointer to a newly allocated buffer of size SIZE, exiting
+   on failure.  SIZE should be nonzero.  */
+static void *
+xmalloc(size_t size)
+{
+  void *p = malloc(size);
+  if (!p) {
+    perror(progname);
+    exit(EXIT_FAILURE);
+  }
+  return p;
+}
+
 #if ! HAVE_TZSET
 # undef tzset
 # define tzset zdump_tzset
@@ -390,21 +242,13 @@ tzalloc(char const *val)
 
     while (*e++)
       continue;
-    env = malloc(sumsize(sizeof *environ,
-			 (e - environ) * sizeof *environ));
-    if (! env) {
-      perror(progname);
-      exit(EXIT_FAILURE);
-    }
+    env = xmalloc(sumsize(sizeof *environ,
+			  (e - environ) * sizeof *environ));
     to = 1;
     for (e = environ; (env[to] = *e); e++)
       to += strncmp(*e, "TZ=", 3) != 0;
   }
-  env0 = malloc(sumsize(sizeof "TZ=", strlen(val)));
-  if (! env0) {
-    perror(progname);
-    exit(EXIT_FAILURE);
-  }
+  env0 = xmalloc(sumsize(sizeof "TZ=", strlen(val)));
   env[0] = strcat(strcpy(env0, "TZ="), val);
   environ = fakeenv = env;
   tzset();
@@ -525,11 +369,7 @@ saveabbr(char **buf, size_t *bufalloc, struct tm const *tmp)
 	 to avoid O(N**2) behavior on repeated calls.  */
       *bufalloc = sumsize(*bufalloc, ablen + 1);
 
-      *buf = malloc(*bufalloc);
-      if (! *buf) {
-	perror(progname);
-	exit(EXIT_FAILURE);
-      }
+      *buf = xmalloc(*bufalloc);
     }
     return strcpy(*buf, ab);
   }
@@ -550,10 +390,18 @@ static void
 usage(FILE * const stream, const int status)
 {
 	fprintf(stream,
-_("%s: usage: %s [--version] [--help] [-{vV}] [-{ct} [lo,]hi] zonename ...\n"
+_("%s: usage: %s OPTIONS ZONENAME ...\n"
+  "Options include:\n"
+  "  -c [L,]U   Start at year L (default -500), end before year U (default 2500)\n"
+  "  -t [L,]U   Start at time L, end before time U (in seconds since 1970)\n"
+  "  -i         List transitions briefly (format is experimental)\n" \
+  "  -v         List transitions verbosely\n"
+  "  -V         List transitions a bit less verbosely\n"
+  "  --help     Output this help\n"
+  "  --version  Output version info\n"
   "\n"
   "Report bugs to %s.\n"),
-		       progname, progname, REPORT_BUGS_TO);
+		progname, progname, REPORT_BUGS_TO);
 	if (status == EXIT_SUCCESS)
 	  close_file(stream);
 	exit(status);
@@ -565,7 +413,6 @@ main(int argc, char *argv[])
 	/* These are static so that they're initially zero.  */
 	static char *		abbrev;
 	static size_t		abbrevsize;
-	static struct tm	newtm;
 
 	register int		i;
 	register bool		vflag;
@@ -575,11 +422,7 @@ main(int argc, char *argv[])
 	register time_t		cutlotime;
 	register time_t		cuthitime;
 	time_t			now;
-	time_t			t;
-	time_t			newt;
-	struct tm		tm;
-	register struct tm *	tmp;
-	register struct tm *	newtmp;
+	bool iflag = false;
 
 	cutlotime = absolute_min_time;
 	cuthitime = absolute_max_time;
@@ -601,9 +444,10 @@ main(int argc, char *argv[])
 	vflag = Vflag = false;
 	cutarg = cuttimes = NULL;
 	for (;;)
-	  switch (getopt(argc, argv, "c:t:vV")) {
+	  switch (getopt(argc, argv, "c:it:vV")) {
 	  case 'c': cutarg = optarg; break;
 	  case 't': cuttimes = optarg; break;
+	  case 'i': iflag = true; break;
 	  case 'v': vflag = true; break;
 	  case 'V': Vflag = true; break;
 	  case -1:
@@ -615,7 +459,7 @@ main(int argc, char *argv[])
 	  }
  arg_processing_done:;
 
-	if (vflag | Vflag) {
+	if (iflag | vflag | Vflag) {
 		intmax_t	lo;
 		intmax_t	hi;
 		char *loend, *hiend;
@@ -672,7 +516,9 @@ main(int argc, char *argv[])
 		}
 	}
 	gmtzinit();
-	now = time(NULL);
+	INITIALIZE (now);
+	if (! (iflag | vflag | Vflag))
+	  now = time(NULL);
 	longest = 0;
 	for (i = optind; i < argc; i++) {
 	  size_t arglen = strlen(argv[i]);
@@ -683,48 +529,66 @@ main(int argc, char *argv[])
 	for (i = optind; i < argc; ++i) {
 		timezone_t tz = tzalloc(argv[i]);
 		char const *ab;
+		time_t t;
+		struct tm tm, newtm;
+		bool tm_ok;
 		if (!tz) {
 		  perror(argv[i]);
 		  return EXIT_FAILURE;
 		}
-		if (! (vflag | Vflag)) {
+		if (! (iflag | vflag | Vflag)) {
 			show(tz, argv[i], now, false);
 			tzfree(tz);
 			continue;
 		}
 		warned = false;
 		t = absolute_min_time;
-		if (!Vflag) {
+		if (! (iflag | Vflag)) {
 			show(tz, argv[i], t, true);
 			t += SECSPERDAY;
 			show(tz, argv[i], t, true);
 		}
 		if (t < cutlotime)
 			t = cutlotime;
-		tmp = my_localtime_rz(tz, &t, &tm);
-		if (tmp)
+		tm_ok = my_localtime_rz(tz, &t, &tm) != NULL;
+		if (tm_ok) {
 		  ab = saveabbr(&abbrev, &abbrevsize, &tm);
+		  if (iflag) {
+		    showtrans("\nTZ=%f", &tm, t, ab, argv[i]);
+		    showtrans("-\t-\t%Q", &tm, t, ab, argv[i]);
+		  }
+		}
 		while (t < cuthitime) {
-			newt = ((t < absolute_max_time - SECSPERDAY / 2
-				 && t + SECSPERDAY / 2 < cuthitime)
-				? t + SECSPERDAY / 2
-				: cuthitime);
-			newtmp = localtime_rz(tz, &newt, &newtm);
-			if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
-				(delta(&newtm, &tm) != (newt - t) ||
-				newtm.tm_isdst != tm.tm_isdst ||
-				strcmp(abbr(&newtm), ab) != 0)) {
-					newt = hunt(tz, argv[i], t, newt);
-					newtmp = localtime_rz(tz, &newt, &newtm);
-					if (newtmp)
-					  ab = saveabbr(&abbrev, &abbrevsize,
-							&newtm);
-			}
-			t = newt;
-			tm = newtm;
-			tmp = newtmp;
+		  time_t newt = ((t < absolute_max_time - SECSPERDAY / 2
+				  && t + SECSPERDAY / 2 < cuthitime)
+				 ? t + SECSPERDAY / 2
+				 : cuthitime);
+		  struct tm *newtmp = localtime_rz(tz, &newt, &newtm);
+		  bool newtm_ok = newtmp != NULL;
+		  if (! (tm_ok & newtm_ok
+			 ? (delta(&newtm, &tm) == newt - t
+			    && newtm.tm_isdst == tm.tm_isdst
+			    && strcmp(abbr(&newtm), ab) == 0)
+			 : tm_ok == newtm_ok)) {
+		    newt = hunt(tz, argv[i], t, newt);
+		    newtmp = localtime_rz(tz, &newt, &newtm);
+		    newtm_ok = newtmp != NULL;
+		    if (iflag)
+		      showtrans("%Y-%m-%d\t%L\t%Q", newtmp, newt,
+				newtm_ok ? abbr(&newtm) : NULL, argv[i]);
+		    else {
+		      show(tz, argv[i], newt - 1, true);
+		      show(tz, argv[i], newt, true);
+		    }
+		  }
+		  t = newt;
+		  tm_ok = newtm_ok;
+		  if (newtm_ok) {
+		    ab = saveabbr(&abbrev, &abbrevsize, &newtm);
+		    tm = newtm;
+		  }
 		}
-		if (!Vflag) {
+		if (! (iflag | Vflag)) {
 			t = absolute_max_time;
 			t -= SECSPERDAY;
 			show(tz, argv[i], t, true);
@@ -790,12 +654,11 @@ hunt(timezone_t tz, char *name, time_t lot, time_t hit)
 	char const *		ab;
 	time_t			t;
 	struct tm		lotm;
-	register struct tm *	lotmp;
 	struct tm		tm;
-	register struct tm *	tmp;
+	bool lotm_ok = my_localtime_rz(tz, &lot, &lotm) != NULL;
+	bool tm_ok;
 
-	lotmp = my_localtime_rz(tz, &lot, &lotm);
-	if (lotmp)
+	if (lotm_ok)
 	  ab = saveabbr(&loab, &loabsize, &lotm);
 	for ( ; ; ) {
 		time_t diff = hit - lot;
@@ -807,18 +670,17 @@ hunt(timezone_t tz, char *name, time_t lot, time_t hit)
 			++t;
 		else if (t >= hit)
 			--t;
-		tmp = my_localtime_rz(tz, &t, &tm);
-		if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
-			(delta(&tm, &lotm) == (t - lot) &&
-			tm.tm_isdst == lotm.tm_isdst &&
-			strcmp(abbr(&tm), ab) == 0)) {
-				lot = t;
-				lotm = tm;
-				lotmp = tmp;
+		tm_ok = my_localtime_rz(tz, &t, &tm) != NULL;
+		if (lotm_ok & tm_ok
+		    ? (delta(&tm, &lotm) == t - lot
+		       && tm.tm_isdst == lotm.tm_isdst
+		       && strcmp(abbr(&tm), ab) == 0)
+		    : lotm_ok == tm_ok) {
+		  lot = t;
+		  if (tm_ok)
+		    lotm = tm;
 		} else	hit = t;
 	}
-	show(tz, name, lot, true);
-	show(tz, name, hit, true);
 	return hit;
 }
 
@@ -862,13 +724,20 @@ adjusted_yday(struct tm const *a, struct tm const *b)
 
 /* If A is the broken-down local time and B the broken-down UTC for
    the same instant, return A's UTC offset in seconds, where positive
-   offsets are east of Greenwich.  On failure, return LONG_MIN.  */
+   offsets are east of Greenwich.  On failure, return LONG_MIN.
+
+   If T is nonnull, *T is the timestamp that corresponds to A; call
+   my_gmtime_r and use its result instead of B.  Otherwise, B is the
+   possibly nonnull result of an earlier call to my_gmtime_r.  */
 static long
-gmtoff(struct tm const *a, struct tm const *b)
+gmtoff(struct tm const *a, time_t *t, struct tm const *b)
 {
 #ifdef TM_GMTOFF
   return a->TM_GMTOFF;
 #else
+  struct tm tm;
+  if (t)
+    b = my_gmtime_r(t, &tm);
   if (! b)
     return LONG_MIN;
   else {
@@ -907,7 +776,7 @@ show(timezone_t tz, char *zone, time_t t, bool v)
 		if (*abbr(tmp) != '\0')
 			printf(" %s", abbr(tmp));
 		if (v) {
-			long off = gmtoff(tmp, gmtmp);
+			long off = gmtoff(tmp, NULL, gmtmp);
 			printf(" isdst=%d", tmp->tm_isdst);
 			if (off != LONG_MIN)
 			  printf(" gmtoff=%ld", off);
@@ -918,6 +787,206 @@ show(timezone_t tz, char *zone, time_t t, bool v)
 		abbrok(abbr(tmp), zone);
 }
 
+/* Store into BUF, of size SIZE, a formatted local time taken from *TM.
+   Use ISO 8601 format +HH:MM:SS.  Omit :SS if SS is zero, and omit
+   :MM too if MM is also zero.
+
+   Return the length of the resulting string.  If the string does not
+   fit, return the length that the string would have been if it had
+   fit; do not overrun the output buffer.  */
+static int
+format_local_time(char *buf, size_t size, struct tm const *tm)
+{
+  int ss = tm->tm_sec, mm = tm->tm_min, hh = tm->tm_hour;
+  return (ss
+	  ? snprintf(buf, size, "%02d:%02d:%02d", hh, mm, ss)
+	  : mm
+	  ? snprintf(buf, size, "%02d:%02d", hh, mm)
+	  : snprintf(buf, size, "%02d", hh));
+}
+
+/* Store into BUF, of size SIZE, a formatted UTC offset for the
+   localtime *TM corresponding to time T.  Use ISO 8601 format
+   +HHMMSS, or -HHMMSS for timestamps west of Greenwich; use the
+   format -00 for unknown UTC offsets.  If the hour needs more than
+   two digits to represent, extend the length of HH as needed.
+   Otherwise, omit SS if SS is zero, and omit MM too if MM is also
+   zero.
+
+   Return the length of the resulting string, or -1 if the result is
+   not representable as a string.  If the string does not fit, return
+   the length that the string would have been if it had fit; do not
+   overrun the output buffer.  */
+static int
+format_utc_offset(char *buf, size_t size, struct tm const *tm, time_t t)
+{
+  long off = gmtoff(tm, &t, NULL);
+  char sign = ((off < 0
+		|| (off == 0
+		    && (*abbr(tm) == '-' || strcmp(abbr(tm), "zzz") == 0)))
+	       ? '-' : '+');
+  long hh;
+  int mm, ss;
+  if (off < 0)
+    {
+      if (off == LONG_MIN)
+	return -1;
+      off = -off;
+    }
+  ss = off % 60;
+  mm = off / 60 % 60;
+  hh = off / 60 / 60;
+  return (ss || 100 <= hh
+	  ? snprintf(buf, size, "%c%02ld%02d%02d", sign, hh, mm, ss)
+	  : mm
+	  ? snprintf(buf, size, "%c%02ld%02d", sign, hh, mm)
+	  : snprintf(buf, size, "%c%02ld", sign, hh));
+}
+
+/* Store into BUF (of size SIZE) a quoted string representation of P.
+   If the representation's length is less than SIZE, return the
+   length; the representation is not null terminated.  Otherwise
+   return SIZE, to indicate that BUF is too small.  */
+static size_t
+format_quoted_string(char *buf, size_t size, char const *p)
+{
+  char *b = buf;
+  size_t s = size;
+  if (!s)
+    return size;
+  *b++ = '"', s--;
+  for (;;) {
+    char c = *p++;
+    if (s <= 1)
+      return size;
+    switch (c) {
+    default: *b++ = c, s--; continue;
+    case '\0': *b++ = '"', s--; return size - s;
+    case '"': case '\\': break;
+    case ' ': c = 's'; break;
+    case '\f': c = 'f'; break;
+    case '\n': c = 'n'; break;
+    case '\r': c = 'r'; break;
+    case '\t': c = 't'; break;
+    case '\v': c = 'v'; break;
+    }
+    *b++ = '\\', *b++ = c, s -= 2;
+  }
+}
+
+/* Store into BUF (of size SIZE) a timestamp formatted by TIME_FMT.
+   TM is the broken-down time, T the seconds count, AB the time zone
+   abbreviation, and ZONE_NAME the zone name.  Return true if
+   successful, false if the output would require more than SIZE bytes.
+   TIME_FMT uses the same format that strftime uses, with these
+   additions:
+
+   %f zone name
+   %L local time as per format_local_time
+   %Q like "U\t%Z\tD" where U is the UTC offset as for format_utc_offset
+      and D is the isdst flag; except omit D if it is zero, omit %Z if
+      it equals U, quote and escape %Z if it contains nonalphabetics,
+      and omit any trailing tabs.  */
+
+static bool
+istrftime(char *buf, size_t size, char const *time_fmt,
+	  struct tm const *tm, time_t t, char const *ab, char const *zone_name)
+{
+  char *b = buf;
+  size_t s = size;
+  char const *f = time_fmt, *p;
+
+  for (p = f; ; p++)
+    if (*p == '%' && p[1] == '%')
+      p++;
+    else if (!*p
+	     || (*p == '%'
+		 && (p[1] == 'f' || p[1] == 'L' || p[1] == 'Q'))) {
+      size_t formatted_len;
+      size_t f_prefix_len = p - f;
+      size_t f_prefix_copy_size = p - f + 2;
+      char fbuf[100];
+      bool oversized = sizeof fbuf <= f_prefix_copy_size;
+      char *f_prefix_copy = oversized ? xmalloc(f_prefix_copy_size) : fbuf;
+      memcpy(f_prefix_copy, f, f_prefix_len);
+      strcpy(f_prefix_copy + f_prefix_len, "X");
+      formatted_len = strftime(b, s, f_prefix_copy, tm);
+      if (oversized)
+	free(f_prefix_copy);
+      if (formatted_len == 0)
+	return false;
+      formatted_len--;
+      b += formatted_len, s -= formatted_len;
+      if (!*p++)
+	break;
+      switch (*p) {
+      case 'f':
+	formatted_len = format_quoted_string(b, s, zone_name);
+	break;
+      case 'L':
+	formatted_len = format_local_time(b, s, tm);
+	break;
+      case 'Q':
+	{
+	  bool show_abbr;
+	  int offlen = format_utc_offset(b, s, tm, t);
+	  if (! (0 <= offlen && offlen < s))
+	    return false;
+	  show_abbr = strcmp(b, ab) != 0;
+	  b += offlen, s -= offlen;
+	  if (show_abbr) {
+	    char const *abp;
+	    size_t len;
+	    if (s <= 1)
+	      return false;
+	    *b++ = '\t', s--;
+	    for (abp = ab; is_alpha(*abp); abp++)
+	      continue;
+	    len = (!*abp && *ab
+		   ? snprintf(b, s, "%s", ab)
+		   : format_quoted_string(b, s, ab));
+	    if (s <= len)
+	      return false;
+	    b += len, s -= len;
+	  }
+	  formatted_len = (tm->tm_isdst
+			   ? snprintf(b, s, &"\t\t%d"[show_abbr], tm->tm_isdst)
+			   : 0);
+	}
+	break;
+      }
+      if (s <= formatted_len)
+	return false;
+      b += formatted_len, s -= formatted_len;
+      f = p + 1;
+    }
+  *b = '\0';
+  return true;
+}
+
+/* Show a time transition.  */
+static void
+showtrans(char const *time_fmt, struct tm const *tm, time_t t, char const *ab,
+	  char const *zone_name)
+{
+  if (!tm) {
+    printf(tformat(), t);
+    putchar('\n');
+  } else {
+    char stackbuf[1000];
+    size_t size = sizeof stackbuf;
+    char *buf = stackbuf;
+    char *bufalloc = NULL;
+    while (! istrftime(buf, size, time_fmt, tm, t, ab, zone_name)) {
+      size = sumsize(size, size);
+      free(bufalloc);
+      buf = bufalloc = xmalloc(size);
+    }
+    puts(buf);
+    free(bufalloc);
+  }
+}
+
 static char const *
 abbr(struct tm const *tmp)
 {
diff --git a/timezone/zic.c b/timezone/zic.c
index 78ab870941..068fb43318 100644
--- a/timezone/zic.c
+++ b/timezone/zic.c
@@ -5,10 +5,12 @@
 
 #include "version.h"
 #include "private.h"
-#include "locale.h"
 #include "tzfile.h"
 
+#include <fcntl.h>
+#include <locale.h>
 #include <stdarg.h>
+#include <stddef.h>
 
 #define	ZIC_VERSION_PRE_2013 '2'
 #define	ZIC_VERSION	'3'
@@ -16,12 +18,20 @@
 typedef int_fast64_t	zic_t;
 #define ZIC_MIN INT_FAST64_MIN
 #define ZIC_MAX INT_FAST64_MAX
+#define PRIdZIC PRIdFAST64
 #define SCNdZIC SCNdFAST64
 
 #ifndef ZIC_MAX_ABBR_LEN_WO_WARN
 #define ZIC_MAX_ABBR_LEN_WO_WARN	6
 #endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
 
+#ifdef HAVE_DIRECT_H
+# include <direct.h>
+# include <io.h>
+# undef mkdir
+# define mkdir(name, mode) _mkdir(name)
+#endif
+
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
@@ -31,9 +41,18 @@ typedef int_fast64_t	zic_t;
 #define MKDIR_UMASK 0755
 #endif
 
+/* The maximum ptrdiff_t value, for pre-C99 platforms.  */
+#ifndef PTRDIFF_MAX
+static ptrdiff_t const PTRDIFF_MAX = MAXVAL(ptrdiff_t, TYPE_BIT(ptrdiff_t));
+#endif
+
+/* The type and printf format for line numbers.  */
+typedef intmax_t lineno;
+#define PRIdLINENO PRIdMAX
+
 struct rule {
 	const char *	r_filename;
-	int		r_linenum;
+	lineno		r_linenum;
 	const char *	r_name;
 
 	zic_t		r_loyear;	/* for example, 1986 */
@@ -56,7 +75,7 @@ struct rule {
 	zic_t		r_stdoff;	/* offset from standard time */
 	const char *	r_abbrvar;	/* variable part of abbreviation */
 
-	int		r_todo;		/* a rule to do (used in outzone) */
+	bool		r_todo;		/* a rule to do (used in outzone) */
 	zic_t		r_temp;		/* used in outzone */
 };
 
@@ -70,7 +89,7 @@ struct rule {
 
 struct zone {
 	const char *	z_filename;
-	int		z_linenum;
+	lineno		z_linenum;
 
 	const char *	z_name;
 	zic_t		z_gmtoff;
@@ -81,23 +100,31 @@ struct zone {
 	zic_t		z_stdoff;
 
 	struct rule *	z_rules;
-	int		z_nrules;
+	ptrdiff_t	z_nrules;
 
 	struct rule	z_untilrule;
 	zic_t		z_untiltime;
 };
 
+#if !HAVE_POSIX_DECLS
 extern int	getopt(int argc, char * const argv[],
 			const char * options);
 extern int	link(const char * fromname, const char * toname);
 extern char *	optarg;
 extern int	optind;
+#endif
 
 #if ! HAVE_LINK
-# define link(from, to) (-1)
+# define link(from, to) (errno = ENOTSUP, -1)
 #endif
 #if ! HAVE_SYMLINK
-# define symlink(from, to) (-1)
+# define readlink(file, buf, size) (errno = ENOTSUP, -1)
+# define symlink(from, to) (errno = ENOTSUP, -1)
+# define S_ISLNK(m) 0
+#endif
+#ifndef AT_SYMLINK_FOLLOW
+# define linkat(fromdir, from, todir, to, flag) \
+    (itssymlink(from) ? (errno = ENOTSUP, -1) : link(from, to))
 #endif
 
 static void	addtt(zic_t starttime, int type);
@@ -105,7 +132,7 @@ static int	addtype(zic_t, char const *, bool, bool, bool);
 static void	leapadd(zic_t, bool, int, int);
 static void	adjleap(void);
 static void	associate(void);
-static void	dolink(const char * fromfield, const char * tofield);
+static void	dolink(const char *, const char *, bool);
 static char **	getfields(char * buf);
 static zic_t	gethms(const char * string, const char * errstring,
 		       bool);
@@ -116,24 +143,32 @@ static void	inrule(char ** fields, int nfields);
 static bool	inzcont(char ** fields, int nfields);
 static bool	inzone(char ** fields, int nfields);
 static bool	inzsub(char **, int, bool);
-static int	itsdir(const char * name);
+static bool	itsdir(char const *);
+static bool	itssymlink(char const *);
 static bool	is_alpha(char a);
 static char	lowerit(char);
-static bool	mkdirs(char *);
+static void	mkdirs(char const *, bool);
 static void	newabbr(const char * abbr);
 static zic_t	oadd(zic_t t1, zic_t t2);
-static void	outzone(const struct zone * zp, int ntzones);
+static void	outzone(const struct zone * zp, ptrdiff_t ntzones);
 static zic_t	rpytime(const struct rule * rp, zic_t wantedy);
 static void	rulesub(struct rule * rp,
 			const char * loyearp, const char * hiyearp,
 			const char * typep, const char * monthp,
 			const char * dayp, const char * timep);
 static zic_t	tadd(zic_t t1, zic_t t2);
-static bool	yearistype(int year, const char * type);
+static bool	yearistype(zic_t year, const char * type);
 
 /* Bound on length of what %z can expand to.  */
 enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };
 
+/* If true, work around a bug in Qt 5.6.1 and earlier, which mishandles
+   tz binary files whose POSIX-TZ-style strings contain '<'; see
+   QTBUG-53071 <https://bugreports.qt.io/browse/QTBUG-53071>.  This
+   workaround will no longer be needed when Qt 5.6.1 and earlier are
+   obsolete, say in the year 2021.  */
+enum { WORK_AROUND_QTBUG_53071 = true };
+
 static int		charcnt;
 static bool		errors;
 static bool		warnings;
@@ -142,17 +177,17 @@ static int		leapcnt;
 static bool		leapseen;
 static zic_t		leapminyear;
 static zic_t		leapmaxyear;
-static int		linenum;
+static lineno		linenum;
 static int		max_abbrvar_len = PERCENT_Z_LEN_BOUND;
 static int		max_format_len;
 static zic_t		max_year;
 static zic_t		min_year;
 static bool		noise;
 static const char *	rfilename;
-static int		rlinenum;
+static lineno		rlinenum;
 static const char *	progname;
-static int		timecnt;
-static int		timecnt_alloc;
+static ptrdiff_t	timecnt;
+static ptrdiff_t	timecnt_alloc;
 static int		typecnt;
 
 /*
@@ -237,23 +272,23 @@ static int		typecnt;
 #define YR_ONLY		2
 
 static struct rule *	rules;
-static int		nrules;	/* number of rules */
-static int		nrules_alloc;
+static ptrdiff_t	nrules;	/* number of rules */
+static ptrdiff_t	nrules_alloc;
 
 static struct zone *	zones;
-static int		nzones;	/* number of zones */
-static int		nzones_alloc;
+static ptrdiff_t	nzones;	/* number of zones */
+static ptrdiff_t	nzones_alloc;
 
 struct link {
 	const char *	l_filename;
-	int		l_linenum;
+	lineno		l_linenum;
 	const char *	l_from;
 	const char *	l_to;
 };
 
 static struct link *	links;
-static int		nlinks;
-static int		nlinks_alloc;
+static ptrdiff_t	nlinks;
+static ptrdiff_t	nlinks_alloc;
 
 struct lookup {
 	const char *	l_word;
@@ -339,6 +374,7 @@ static const int	len_years[2] = {
 
 static struct attype {
 	zic_t		at;
+	bool		dontmerge;
 	unsigned char	type;
 } *			attypes;
 static zic_t		gmtoffs[TZ_MAX_TYPES];
@@ -406,15 +442,16 @@ ecpyalloc (char const *str)
 }
 
 static void *
-growalloc(void *ptr, size_t itemsize, int nitems, int *nitems_alloc)
+growalloc(void *ptr, size_t itemsize, ptrdiff_t nitems, ptrdiff_t *nitems_alloc)
 {
 	if (nitems < *nitems_alloc)
 		return ptr;
 	else {
-		int amax = INT_MAX < SIZE_MAX ? INT_MAX : SIZE_MAX;
+		ptrdiff_t nitems_max = PTRDIFF_MAX - WORK_AROUND_QTBUG_53071;
+		ptrdiff_t amax = nitems_max < SIZE_MAX ? nitems_max : SIZE_MAX;
 		if ((amax - 1) / 3 * 2 < *nitems_alloc)
-			memory_exhausted(_("int overflow"));
-		*nitems_alloc = *nitems_alloc + (*nitems_alloc >> 1) + 1;
+			memory_exhausted(_("integer overflow"));
+		*nitems_alloc += (*nitems_alloc >> 1) + 1;
 		return erealloc(ptr, size_product(*nitems_alloc, itemsize));
 	}
 }
@@ -424,8 +461,7 @@ growalloc(void *ptr, size_t itemsize, int nitems, int *nitems_alloc)
 */
 
 static void
-eats(const char *const name, const int num, const char *const rname,
-     const int rnum)
+eats(char const *name, lineno num, char const *rname, lineno rnum)
 {
 	filename = name;
 	linenum = num;
@@ -434,7 +470,7 @@ eats(const char *const name, const int num, const char *const rname,
 }
 
 static void
-eat(const char *const name, const int num)
+eat(char const *name, lineno num)
 {
 	eats(name, num, NULL, -1);
 }
@@ -448,10 +484,10 @@ verror(const char *const string, va_list args)
 	** on BSD systems.
 	*/
 	if (filename)
-	  fprintf(stderr, _("\"%s\", line %d: "), filename, linenum);
+	  fprintf(stderr, _("\"%s\", line %"PRIdLINENO": "), filename, linenum);
 	vfprintf(stderr, string, args);
 	if (rfilename != NULL)
-		fprintf(stderr, _(" (rule from \"%s\", line %d)"),
+		fprintf(stderr, _(" (rule from \"%s\", line %"PRIdLINENO")"),
 			rfilename, rlinenum);
 	fprintf(stderr, "\n");
 }
@@ -478,15 +514,15 @@ warning(const char *const string, ...)
 }
 
 static void
-close_file(FILE *stream, char const *name)
+close_file(FILE *stream, char const *dir, char const *name)
 {
   char const *e = (ferror(stream) ? _("I/O error")
 		   : fclose(stream) != 0 ? strerror(errno) : NULL);
   if (e) {
-    fprintf(stderr, "%s: ", progname);
-    if (name)
-      fprintf(stderr, "%s: ", name);
-    fprintf(stderr, "%s\n", e);
+    fprintf(stderr, "%s: %s%s%s%s%s\n", progname,
+	    dir ? dir : "", dir ? "/" : "",
+	    name ? name : "", name ? ": " : "",
+	    e);
     exit(EXIT_FAILURE);
   }
 }
@@ -501,10 +537,30 @@ usage(FILE *stream, int status)
 	    "Report bugs to %s.\n"),
 	  progname, progname, REPORT_BUGS_TO);
   if (status == EXIT_SUCCESS)
-    close_file(stream, NULL);
+    close_file(stream, NULL, NULL);
   exit(status);
 }
 
+/* Change the working directory to DIR, possibly creating DIR and its
+   ancestors.  After this is done, all files are accessed with names
+   relative to DIR.  */
+static void
+change_directory (char const *dir)
+{
+  if (chdir(dir) != 0) {
+    int chdir_errno = errno;
+    if (chdir_errno == ENOENT) {
+      mkdirs(dir, false);
+      chdir_errno = chdir(dir) == 0 ? 0 : errno;
+    }
+    if (chdir_errno != 0) {
+      fprintf(stderr, _("%s: Can't chdir to %s: %s\n"),
+	      progname, dir, strerror(chdir_errno));
+      exit(EXIT_FAILURE);
+    }
+  }
+}
+
 static const char *	psxrules;
 static const char *	lcltime;
 static const char *	directory;
@@ -514,9 +570,8 @@ static const char *	yitcommand;
 int
 main(int argc, char **argv)
 {
-	register int	i;
-	register int	j;
-	register int	c;
+	register int c, k;
+	register ptrdiff_t i, j;
 
 #ifdef S_IWGRP
 	umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
@@ -534,12 +589,12 @@ main(int argc, char **argv)
 			_("wild compilation-time specification of zic_t"));
 		return EXIT_FAILURE;
 	}
-	for (i = 1; i < argc; ++i)
-		if (strcmp(argv[i], "--version") == 0) {
+	for (k = 1; k < argc; k++)
+		if (strcmp(argv[k], "--version") == 0) {
 			printf("zic %s%s\n", PKGVERSION, TZVERSION);
-			close_file(stdout, NULL);
+			close_file(stdout, NULL, NULL);
 			return EXIT_SUCCESS;
-		} else if (strcmp(argv[i], "--help") == 0) {
+		} else if (strcmp(argv[k], "--help") == 0) {
 			usage(stdout, EXIT_SUCCESS);
 		}
 	while ((c = getopt(argc, argv, "d:l:p:L:vsy:")) != EOF && c != -1)
@@ -615,11 +670,12 @@ _("%s: More than one -L option specified\n"),
 		adjleap();
 	}
 
-	for (i = optind; i < argc; ++i)
-		infile(argv[i]);
+	for (k = optind; k < argc; k++)
+		infile(argv[k]);
 	if (errors)
 		return EXIT_FAILURE;
 	associate();
+	change_directory(directory);
 	for (i = 0; i < nzones; i = j) {
 		/*
 		** Find the next non-continuation zone entry.
@@ -633,7 +689,7 @@ _("%s: More than one -L option specified\n"),
 	*/
 	for (i = 0; i < nlinks; ++i) {
 		eat(links[i].l_filename, links[i].l_linenum);
-		dolink(links[i].l_from, links[i].l_to);
+		dolink(links[i].l_from, links[i].l_to, false);
 		if (noise)
 			for (j = 0; j < nlinks; ++j)
 				if (strcmp(links[i].l_to,
@@ -642,11 +698,11 @@ _("%s: More than one -L option specified\n"),
 	}
 	if (lcltime != NULL) {
 		eat(_("command line"), 1);
-		dolink(lcltime, TZDEFAULT);
+		dolink(lcltime, TZDEFAULT, true);
 	}
 	if (psxrules != NULL) {
 		eat(_("command line"), 1);
-		dolink(psxrules, TZDEFRULES);
+		dolink(psxrules, TZDEFRULES, true);
 	}
 	if (warnings && (ferror(stderr) || fclose(stderr) != 0))
 	  return EXIT_FAILURE;
@@ -658,7 +714,7 @@ componentcheck(char const *name, char const *component,
 	       char const *component_end)
 {
 	enum { component_len_max = 14 };
-	size_t component_len = component_end - component;
+	ptrdiff_t component_len = component_end - component;
 	if (component_len == 0) {
 	  if (!*name)
 	    error (_("empty file name"));
@@ -673,8 +729,9 @@ componentcheck(char const *name, char const *component,
 	}
 	if (0 < component_len && component_len <= 2
 	    && component[0] == '.' && component_end[-1] == '.') {
+	  int len = component_len;
 	  error(_("file name '%s' contains '%.*s' component"),
-		name, (int) component_len, component);
+		name, len, component);
 	  return false;
 	}
 	if (noise) {
@@ -723,118 +780,138 @@ namecheck(const char *name)
 	return componentcheck(name, component, cp);
 }
 
+/* Create symlink contents suitable for symlinking FROM to TO, as a
+   freshly allocated string.  FROM should be a relative file name, and
+   is relative to the global variable DIRECTORY.  TO can be either
+   relative or absolute.  */
 static char *
-relname(char const *dir, char const *base)
-{
-  if (*base == '/')
-    return ecpyalloc(base);
-  else {
-    size_t dir_len = strlen(dir);
-    bool needs_slash = dir_len && dir[dir_len - 1] != '/';
-    char *result = emalloc(dir_len + needs_slash + strlen(base) + 1);
-    result[dir_len] = '/';
-    strcpy(result + dir_len + needs_slash, base);
-    return memcpy(result, dir, dir_len);
+relname(char const *from, char const *to)
+{
+  size_t i, taillen, dotdotetcsize;
+  size_t dir_len = 0, dotdots = 0, linksize = SIZE_MAX;
+  char const *f = from;
+  char *result = NULL;
+  if (*to == '/') {
+    /* Make F absolute too.  */
+    size_t len = strlen(directory);
+    bool needslash = len && directory[len - 1] != '/';
+    linksize = len + needslash + strlen(from) + 1;
+    f = result = emalloc(linksize);
+    strcpy(result, directory);
+    result[len] = '/';
+    strcpy(result + len + needslash, from);
+  }
+  for (i = 0; f[i] && f[i] == to[i]; i++)
+    if (f[i] == '/')
+      dir_len = i + 1;
+  for (; to[i]; i++)
+    dotdots += to[i] == '/' && to[i - 1] != '/';
+  taillen = strlen(f + dir_len);
+  dotdotetcsize = 3 * dotdots + taillen + 1;
+  if (dotdotetcsize <= linksize) {
+    if (!result)
+      result = emalloc(dotdotetcsize);
+    for (i = 0; i < dotdots; i++)
+      memcpy(result + 3 * i, "../", 3);
+    memmove(result + 3 * dotdots, f + dir_len, taillen + 1);
   }
+  return result;
+}
+
+/* Hard link FROM to TO, following any symbolic links.
+   Return 0 if successful, an error number otherwise.  */
+static int
+hardlinkerr(char const *from, char const *to)
+{
+  int r = linkat(AT_FDCWD, from, AT_FDCWD, to, AT_SYMLINK_FOLLOW);
+  return r == 0 ? 0 : errno;
 }
 
 static void
-dolink(char const *fromfield, char const *tofield)
+dolink(char const *fromfield, char const *tofield, bool staysymlink)
 {
-	register char *	fromname;
-	register char *	toname;
-	register int fromisdir;
+	bool todirs_made = false;
+	int link_errno;
 
-	fromname = relname(directory, fromfield);
-	toname = relname(directory, tofield);
 	/*
 	** We get to be careful here since
 	** there's a fair chance of root running us.
 	*/
-	fromisdir = itsdir(fromname);
-	if (fromisdir) {
-		char const *e = strerror(fromisdir < 0 ? errno : EPERM);
-		fprintf(stderr, _("%s: link from %s failed: %s"),
-			progname, fromname, e);
+	if (itsdir(fromfield)) {
+		fprintf(stderr, _("%s: link from %s/%s failed: %s\n"),
+			progname, directory, fromfield, strerror(EPERM));
 		exit(EXIT_FAILURE);
 	}
-	if (itsdir(toname) <= 0)
-		remove(toname);
-	if (link(fromname, toname) != 0) {
-		int	result;
-
-		if (! mkdirs(toname))
-			exit(EXIT_FAILURE);
-
-		result = link(fromname, toname);
-		if (result != 0) {
-				const char *s = fromfield;
-				const char *t;
-				char *p;
-				size_t dotdots = 0;
-				register char * symlinkcontents = NULL;
-
-				do
-					 t = s;
-				while ((s = strchr(s, '/'))
-				       && ! strncmp (fromfield, tofield,
-						     ++s - fromfield));
-
-				for (s = tofield + (t - fromfield); *s; s++)
-				  dotdots += *s == '/';
-				symlinkcontents
-				  = emalloc(3 * dotdots + strlen(t) + 1);
-				for (p = symlinkcontents; dotdots-- != 0; p += 3)
-				  memcpy(p, "../", 3);
-				strcpy(p, t);
-				result = symlink(symlinkcontents, toname);
-				if (result == 0)
-warning(_("hard link failed, symbolic link used"));
-				free(symlinkcontents);
-		}
-		if (result != 0) {
-			FILE *fp, *tp;
-			int c;
-			fp = fopen(fromname, "rb");
-			if (!fp) {
-				const char *e = strerror(errno);
-				fprintf(stderr,
-					       _("%s: Can't read %s: %s\n"),
-					       progname, fromname, e);
-				exit(EXIT_FAILURE);
-			}
-			tp = fopen(toname, "wb");
-			if (!tp) {
-				const char *e = strerror(errno);
-				fprintf(stderr,
-					       _("%s: Can't create %s: %s\n"),
-					       progname, toname, e);
-				exit(EXIT_FAILURE);
-			}
-			while ((c = getc(fp)) != EOF)
-				putc(c, tp);
-			close_file(fp, fromname);
-			close_file(tp, toname);
-			warning(_("link failed, copy used"));
-		}
+	if (staysymlink)
+	  staysymlink = itssymlink(tofield);
+	if (remove(tofield) == 0)
+	  todirs_made = true;
+	else if (errno != ENOENT) {
+	  char const *e = strerror(errno);
+	  fprintf(stderr, _("%s: Can't remove %s/%s: %s\n"),
+		  progname, directory, tofield, e);
+	  exit(EXIT_FAILURE);
+	}
+	link_errno = staysymlink ? ENOTSUP : hardlinkerr(fromfield, tofield);
+	if (link_errno == ENOENT && !todirs_made) {
+	  mkdirs(tofield, true);
+	  todirs_made = true;
+	  link_errno = hardlinkerr(fromfield, tofield);
+	}
+	if (link_errno != 0) {
+	  bool absolute = *fromfield == '/';
+	  char *linkalloc = absolute ? NULL : relname(fromfield, tofield);
+	  char const *contents = absolute ? fromfield : linkalloc;
+	  int symlink_errno = symlink(contents, tofield) == 0 ? 0 : errno;
+	  if (symlink_errno == ENOENT && !todirs_made) {
+	    mkdirs(tofield, true);
+	    symlink_errno = symlink(contents, tofield) == 0 ? 0 : errno;
+	  }
+	  free(linkalloc);
+	  if (symlink_errno == 0) {
+	    if (link_errno != ENOTSUP)
+	      warning(_("symbolic link used because hard link failed: %s"),
+		      strerror(link_errno));
+	  } else {
+	    FILE *fp, *tp;
+	    int c;
+	    fp = fopen(fromfield, "rb");
+	    if (!fp) {
+	      char const *e = strerror(errno);
+	      fprintf(stderr, _("%s: Can't read %s/%s: %s\n"),
+		      progname, directory, fromfield, e);
+	      exit(EXIT_FAILURE);
+	    }
+	    tp = fopen(tofield, "wb");
+	    if (!tp) {
+	      char const *e = strerror(errno);
+	      fprintf(stderr, _("%s: Can't create %s/%s: %s\n"),
+		      progname, directory, tofield, e);
+	      exit(EXIT_FAILURE);
+	    }
+	    while ((c = getc(fp)) != EOF)
+	      putc(c, tp);
+	    close_file(fp, directory, fromfield);
+	    close_file(tp, directory, tofield);
+	    if (link_errno != ENOTSUP)
+	      warning(_("copy used because hard link failed: %s"),
+		      strerror(link_errno));
+	    else if (symlink_errno != ENOTSUP)
+	      warning(_("copy used because symbolic link failed: %s"),
+		      strerror(symlink_errno));
+	  }
 	}
-	free(fromname);
-	free(toname);
 }
 
 #define TIME_T_BITS_IN_FILE	64
 
-static zic_t const min_time = MINVAL (zic_t, TIME_T_BITS_IN_FILE);
-static zic_t const max_time = MAXVAL (zic_t, TIME_T_BITS_IN_FILE);
+static zic_t const min_time = MINVAL(zic_t, TIME_T_BITS_IN_FILE);
+static zic_t const max_time = MAXVAL(zic_t, TIME_T_BITS_IN_FILE);
 
 /* Estimated time of the Big Bang, in seconds since the POSIX epoch.
    rounded downward to the negation of a power of two that is
    comfortably outside the error bounds.
 
-   zic does not output time stamps before this, partly because they
-   are physically suspect, and partly because GNOME mishandles them; see
-   GNOME bug 730332 <https://bugzilla.gnome.org/show_bug.cgi?id=730332>.
-
    For the time of the Big Bang, see:
 
    Ade PAR, Aghanim N, Armitage-Caplan C et al.  Planck 2013 results.
@@ -855,26 +932,49 @@ static zic_t const max_time = MAXVAL (zic_t, TIME_T_BITS_IN_FILE);
 #define BIG_BANG (- (1LL << 59))
 #endif
 
-static const zic_t big_bang_time = BIG_BANG;
+/* If true, work around GNOME bug 730332
+   <https://bugzilla.gnome.org/show_bug.cgi?id=730332>
+   by refusing to output time stamps before BIG_BANG.
+   Such time stamps are physically suspect anyway.
 
-/* Return 1 if NAME is a directory, 0 if it's something else, -1 if trouble.  */
-static int
+   The GNOME bug is scheduled to be fixed in GNOME 3.22, and if so
+   this workaround will no longer be needed when GNOME 3.21 and
+   earlier are obsolete, say in the year 2021.  */
+enum { WORK_AROUND_GNOME_BUG_730332 = true };
+
+static const zic_t early_time = (WORK_AROUND_GNOME_BUG_730332
+				 ? BIG_BANG
+				 : MINVAL(zic_t, TIME_T_BITS_IN_FILE));
+
+/* Return true if NAME is a directory.  */
+static bool
 itsdir(char const *name)
 {
 	struct stat st;
 	int res = stat(name, &st);
-	if (res != 0)
-		return res;
 #ifdef S_ISDIR
-	return S_ISDIR(st.st_mode) != 0;
-#else
-	{
-		char *nameslashdot = relname(name, ".");
-		res = stat(nameslashdot, &st);
+	if (res == 0)
+		return S_ISDIR(st.st_mode) != 0;
+#endif
+	if (res == 0 || errno == EOVERFLOW) {
+		size_t n = strlen(name);
+		char *nameslashdot = emalloc(n + 3);
+		bool dir;
+		memcpy(nameslashdot, name, n);
+		strcpy(&nameslashdot[n], &"/."[! (n && name[n - 1] != '/')]);
+		dir = stat(nameslashdot, &st) == 0 || errno == EOVERFLOW;
 		free(nameslashdot);
-		return res == 0;
+		return dir;
 	}
-#endif
+	return false;
+}
+
+/* Return true if NAME is a symbolic link.  */
+static bool
+itssymlink(char const *name)
+{
+  char c;
+  return 0 <= readlink(name, &c, 1);
 }
 
 /*
@@ -897,8 +997,7 @@ associate(void)
 {
 	register struct zone *	zp;
 	register struct rule *	rp;
-	register int		base, out;
-	register int		i, j;
+	register ptrdiff_t i, j, base, out;
 
 	if (nrules != 0) {
 		qsort(rules, nrules, sizeof *rules, rcomp);
@@ -976,7 +1075,7 @@ infile(const char *name)
 	register const struct lookup *	lp;
 	register int			nfields;
 	register bool			wantcont;
-	register int			num;
+	register lineno			num;
 	char				buf[BUFSIZ];
 
 	if (strcmp(name, "-") == 0) {
@@ -1017,7 +1116,7 @@ infile(const char *name)
 			lp = byword(fields[0], line_codes);
 			if (lp == NULL)
 				error(_("input line of unknown type"));
-			else switch ((int) (lp->l_value)) {
+			else switch (lp->l_value) {
 				case LC_RULE:
 					inrule(fields, nfields);
 					wantcont = false;
@@ -1046,7 +1145,7 @@ _("%s: panic: Invalid l_value %d\n"),
 		}
 		free(fields);
 	}
-	close_file(fp, filename);
+	close_file(fp, NULL, filename);
 	if (wantcont)
 		error(_("expected continuation line not found"));
 }
@@ -1129,7 +1228,7 @@ inrule(char **fields, int nfields)
 static bool
 inzone(char **fields, int nfields)
 {
-	register int	i;
+	register ptrdiff_t i;
 
 	if (nfields < ZONE_MINFIELDS || nfields > ZONE_MAXFIELDS) {
 		error(_("wrong number of fields on Zone line"));
@@ -1150,8 +1249,8 @@ _("\"Zone %s\" line and -p option are mutually exclusive"),
 	for (i = 0; i < nzones; ++i)
 		if (zones[i].z_name != NULL &&
 			strcmp(zones[i].z_name, fields[ZF_NAME]) == 0) {
-				error(
-_("duplicate zone name %s (file \"%s\", line %d)"),
+				error(_("duplicate zone name %s"
+					" (file \"%s\", line %"PRIdLINENO")"),
 					fields[ZF_NAME],
 					zones[i].z_filename,
 					zones[i].z_linenum);
@@ -1263,7 +1362,7 @@ inleap(char **fields, int nfields)
 {
 	register const char *		cp;
 	register const struct lookup *	lp;
-	register int			i, j;
+	register zic_t			i, j;
 	zic_t				year;
 	int				month, day;
 	zic_t				dayoff, tod;
@@ -1355,7 +1454,7 @@ inleap(char **fields, int nfields)
 			return;
 		}
 		t = tadd(t, tod);
-		if (t < big_bang_time) {
+		if (t < early_time) {
 			error(_("leap second precedes Big Bang"));
 			return;
 		}
@@ -1435,7 +1534,7 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 	cp = loyearp;
 	lp = byword(cp, begin_years);
 	rp->r_lowasnum = lp == NULL;
-	if (!rp->r_lowasnum) switch ((int) lp->l_value) {
+	if (!rp->r_lowasnum) switch (lp->l_value) {
 		case YR_MINIMUM:
 			rp->r_loyear = ZIC_MIN;
 			break;
@@ -1454,7 +1553,7 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 	cp = hiyearp;
 	lp = byword(cp, end_years);
 	rp->r_hiwasnum = lp == NULL;
-	if (!rp->r_hiwasnum) switch ((int) lp->l_value) {
+	if (!rp->r_hiwasnum) switch (lp->l_value) {
 		case YR_MINIMUM:
 			rp->r_hiyear = ZIC_MIN;
 			break;
@@ -1592,15 +1691,18 @@ static void
 writezone(const char *const name, const char *const string, char version)
 {
 	register FILE *			fp;
-	register int			i, j;
+	register ptrdiff_t		i, j;
 	register int			leapcnt32, leapi32;
-	register int			timecnt32, timei32;
+	register ptrdiff_t		timecnt32, timei32;
 	register int			pass;
-	char *				fullname;
 	static const struct tzhead	tzh0;
 	static struct tzhead		tzh;
-	zic_t *ats = emalloc(size_product(timecnt, sizeof *ats + 1));
-	void *typesptr = ats + timecnt;
+	bool dir_checked = false;
+	zic_t one = 1;
+	zic_t y2038_boundary = one << 31;
+	ptrdiff_t nats = timecnt + WORK_AROUND_QTBUG_53071;
+	zic_t *ats = emalloc(size_product(nats, sizeof *ats + 1));
+	void *typesptr = ats + nats;
 	unsigned char *types = typesptr;
 
 	/*
@@ -1612,12 +1714,11 @@ writezone(const char *const name, const char *const string, char version)
 	** Optimize.
 	*/
 	{
-		int	fromi;
-		int	toi;
+		ptrdiff_t fromi, toi;
 
 		toi = 0;
 		fromi = 0;
-		while (fromi < timecnt && attypes[fromi].at < big_bang_time)
+		while (fromi < timecnt && attypes[fromi].at < early_time)
 			++fromi;
 		for ( ; fromi < timecnt; ++fromi) {
 			if (toi > 1 && ((attypes[fromi].at +
@@ -1628,15 +1729,23 @@ writezone(const char *const name, const char *const string, char version)
 						attypes[fromi].type;
 					continue;
 			}
-			if (toi == 0 ||
-				attypes[toi - 1].type != attypes[fromi].type)
+			if (toi == 0
+			    || attypes[fromi].dontmerge
+			    || attypes[toi - 1].type != attypes[fromi].type)
 					attypes[toi++] = attypes[fromi];
 		}
 		timecnt = toi;
 	}
-	if (noise && timecnt > 1200)
+
+	if (noise && timecnt > 1200) {
+	  if (timecnt > TZ_MAX_TIMES)
+		warning(_("reference clients mishandle"
+			  " more than %d transition times"),
+			TZ_MAX_TIMES);
+	  else
 		warning(_("pre-2014 clients may mishandle"
 			  " more than 1200 transition times"));
+	}
 	/*
 	** Transfer.
 	*/
@@ -1644,6 +1753,19 @@ writezone(const char *const name, const char *const string, char version)
 		ats[i] = attypes[i].at;
 		types[i] = attypes[i].type;
 	}
+
+	/* Work around QTBUG-53071 for time stamps less than y2038_boundary - 1,
+	   by inserting a no-op transition at time y2038_boundary - 1.
+	   This works only for timestamps before the boundary, which
+	   should be good enough in practice as QTBUG-53071 should be
+	   long-dead by 2038.  */
+	if (WORK_AROUND_QTBUG_53071 && timecnt != 0
+	    && ats[timecnt - 1] < y2038_boundary - 1 && strchr(string, '<')) {
+	  ats[timecnt] = y2038_boundary - 1;
+	  types[timecnt] = types[timecnt - 1];
+	  timecnt++;
+	}
+
 	/*
 	** Correct for leap seconds.
 	*/
@@ -1681,50 +1803,58 @@ writezone(const char *const name, const char *const string, char version)
 		--leapcnt32;
 		++leapi32;
 	}
-	fullname = relname(directory, name);
 	/*
 	** Remove old file, if any, to snap links.
 	*/
-	if (itsdir(fullname) <= 0 && remove(fullname) != 0 && errno != ENOENT) {
+	if (remove(name) == 0)
+		dir_checked = true;
+	else if (errno != ENOENT) {
 		const char *e = strerror(errno);
 
-		fprintf(stderr, _("%s: Can't remove %s: %s\n"),
-			progname, fullname, e);
+		fprintf(stderr, _("%s: Can't remove %s/%s: %s\n"),
+			progname, directory, name, e);
 		exit(EXIT_FAILURE);
 	}
-	if ((fp = fopen(fullname, "wb")) == NULL) {
-		if (! mkdirs(fullname))
-			exit(EXIT_FAILURE);
-		if ((fp = fopen(fullname, "wb")) == NULL) {
-			const char *e = strerror(errno);
-
-			fprintf(stderr, _("%s: Can't create %s: %s\n"),
-				progname, fullname, e);
-			exit(EXIT_FAILURE);
-		}
+	fp = fopen(name, "wb");
+	if (!fp) {
+	  int fopen_errno = errno;
+	  if (fopen_errno == ENOENT && !dir_checked) {
+	    mkdirs(name, true);
+	    fp = fopen(name, "wb");
+	    fopen_errno = errno;
+	  }
+	  if (!fp) {
+	    fprintf(stderr, _("%s: Can't create %s/%s: %s\n"),
+		    progname, directory, name, strerror(fopen_errno));
+	    exit(EXIT_FAILURE);
+	  }
 	}
 	for (pass = 1; pass <= 2; ++pass) {
-		register int	thistimei, thistimecnt;
-		register int	thisleapi, thisleapcnt;
-		register int	thistimelim, thisleaplim;
+		register ptrdiff_t thistimei, thistimecnt, thistimelim;
+		register int	thisleapi, thisleapcnt, thisleaplim;
 		int		writetype[TZ_MAX_TYPES];
 		int		typemap[TZ_MAX_TYPES];
 		register int	thistypecnt;
 		char		thischars[TZ_MAX_CHARS];
-		char		thischarcnt;
+		int		thischarcnt;
+		bool		toomanytimes;
 		int		indmap[TZ_MAX_CHARS];
 
 		if (pass == 1) {
 			thistimei = timei32;
 			thistimecnt = timecnt32;
+			toomanytimes = thistimecnt >> 31 >> 1 != 0;
 			thisleapi = leapi32;
 			thisleapcnt = leapcnt32;
 		} else {
 			thistimei = 0;
 			thistimecnt = timecnt;
+			toomanytimes = thistimecnt >> 31 >> 31 >> 2 != 0;
 			thisleapi = 0;
 			thisleapcnt = leapcnt;
 		}
+		if (toomanytimes)
+		  error(_("too many transition times"));
 		thistimelim = thistimei + thistimecnt;
 		thisleaplim = thisleapi + thisleapcnt;
 		for (i = 0; i < typecnt; ++i)
@@ -1811,8 +1941,7 @@ writezone(const char *const name, const char *const string, char version)
 				if (strcmp(&thischars[j], thisabbr) == 0)
 					break;
 			if (j == thischarcnt) {
-				strcpy(&thischars[(int) thischarcnt],
-					thisabbr);
+				strcpy(&thischars[thischarcnt], thisabbr);
 				thischarcnt += strlen(thisabbr) + 1;
 			}
 			indmap[abbrinds[i]] = j;
@@ -1894,9 +2023,8 @@ writezone(const char *const name, const char *const string, char version)
 				putc(ttisgmts[i], fp);
 	}
 	fprintf(fp, "\n%s\n", string);
-	close_file(fp, fullname);
+	close_file(fp, directory, name);
 	free(ats);
-	free(fullname);
 }
 
 static char const *
@@ -2097,13 +2225,13 @@ rule_cmp(struct rule const *a, struct rule const *b)
 enum { YEAR_BY_YEAR_ZONE = 1 };
 
 static int
-stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
+stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 {
 	register const struct zone *	zp;
 	register struct rule *		rp;
 	register struct rule *		stdrp;
 	register struct rule *		dstrp;
-	register int			i;
+	register ptrdiff_t		i;
 	register const char *		abbrvar;
 	register int			compat = 0;
 	register int			c;
@@ -2216,11 +2344,11 @@ stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
 }
 
 static void
-outzone(const struct zone *zpfirst, int zonecount)
+outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 {
 	register const struct zone *	zp;
 	register struct rule *		rp;
-	register int			i, j;
+	register ptrdiff_t		i, j;
 	register bool			usestart, useuntil;
 	register zic_t			starttime, untiltime;
 	register zic_t			gmtoff;
@@ -2239,6 +2367,10 @@ outzone(const struct zone *zpfirst, int zonecount)
 	register int			compat;
 	register bool			do_extend;
 	register char			version;
+	ptrdiff_t lastatmax = -1;
+	zic_t one = 1;
+	zic_t y2038_boundary = one << 31;
+	zic_t max_year0;
 
 	max_abbr_len = 2 + max_format_len + max_abbrvar_len;
 	max_envvar_len = 2 * max_abbr_len + 5 * 9;
@@ -2334,21 +2466,22 @@ outzone(const struct zone *zpfirst, int zonecount)
 	}
 	/*
 	** For the benefit of older systems,
-	** generate data from 1900 through 2037.
+	** generate data from 1900 through 2038.
 	*/
 	if (min_year > 1900)
 		min_year = 1900;
-	if (max_year < 2037)
-		max_year = 2037;
+	max_year0 = max_year;
+	if (max_year < 2038)
+		max_year = 2038;
 	for (i = 0; i < zonecount; ++i) {
 		/*
 		** A guess that may well be corrected later.
 		*/
 		stdoff = 0;
 		zp = &zpfirst[i];
-		usestart = i > 0 && (zp - 1)->z_untiltime > big_bang_time;
+		usestart = i > 0 && (zp - 1)->z_untiltime > early_time;
 		useuntil = i < (zonecount - 1);
-		if (useuntil && zp->z_untiltime <= big_bang_time)
+		if (useuntil && zp->z_untiltime <= early_time)
 			continue;
 		gmtoff = zp->z_gmtoff;
 		eat(zp->z_filename, zp->z_linenum);
@@ -2363,7 +2496,7 @@ outzone(const struct zone *zpfirst, int zonecount)
 			if (usestart) {
 				addtt(starttime, type);
 				usestart = false;
-			} else	addtt(big_bang_time, type);
+			} else	addtt(early_time, type);
 		} else for (year = min_year; year <= max_year; ++year) {
 			if (useuntil && year > zp->z_untilrule.r_hiyear)
 				break;
@@ -2378,11 +2511,15 @@ outzone(const struct zone *zpfirst, int zonecount)
 				rp->r_todo = year >= rp->r_loyear &&
 						year <= rp->r_hiyear &&
 						yearistype(year, rp->r_yrtype);
-				if (rp->r_todo)
+				if (rp->r_todo) {
 					rp->r_temp = rpytime(rp, year);
+					rp->r_todo
+					  = (rp->r_temp < y2038_boundary
+					     || year <= max_year0);
+				}
 			}
 			for ( ; ; ) {
-				register int	k;
+				register ptrdiff_t k;
 				register zic_t	jtime, ktime;
 				register zic_t	offset;
 
@@ -2471,6 +2608,10 @@ outzone(const struct zone *zpfirst, int zonecount)
 				offset = oadd(zp->z_gmtoff, rp->r_stdoff);
 				type = addtype(offset, ab, rp->r_stdoff != 0,
 					rp->r_todisstd, rp->r_todisgmt);
+				if (rp->r_hiyear == ZIC_MAX
+				    && ! (0 <= lastatmax
+					  && ktime < attypes[lastatmax].at))
+				  lastatmax = timecnt;
 				addtt(ktime, type);
 			}
 		}
@@ -2502,6 +2643,8 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 				starttime = tadd(starttime, -gmtoff);
 		}
 	}
+	if (0 <= lastatmax)
+	  attypes[lastatmax].dontmerge = true;
 	if (do_extend) {
 		/*
 		** If we're extending the explicitly listed observations
@@ -2523,21 +2666,8 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 			if (attypes[i].at > lastat->at)
 				lastat = &attypes[i];
 		if (lastat->at < rpytime(&xr, max_year - 1)) {
-			/*
-			** Create new type code for the redundant entry,
-			** to prevent it being optimized away.
-			*/
-			if (typecnt >= TZ_MAX_TYPES) {
-				error(_("too many local time types"));
-				exit(EXIT_FAILURE);
-			}
-			gmtoffs[typecnt] = gmtoffs[lastat->type];
-			isdsts[typecnt] = isdsts[lastat->type];
-			ttisstds[typecnt] = ttisstds[lastat->type];
-			ttisgmts[typecnt] = ttisgmts[lastat->type];
-			abbrinds[typecnt] = abbrinds[lastat->type];
-			++typecnt;
 			addtt(rpytime(&xr, max_year + 1), typecnt-1);
+			attypes[timecnt - 1].dontmerge = true;
 		}
 	}
 	writezone(zpfirst->z_name, envvar, version);
@@ -2549,8 +2679,8 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 static void
 addtt(zic_t starttime, int type)
 {
-	if (starttime <= big_bang_time ||
-		(timecnt == 1 && attypes[0].at < big_bang_time)) {
+	if (starttime <= early_time
+	    || (timecnt == 1 && attypes[0].at < early_time)) {
 		gmtoffs[0] = gmtoffs[type];
 		isdsts[0] = isdsts[type];
 		ttisstds[0] = ttisstds[type];
@@ -2565,6 +2695,7 @@ addtt(zic_t starttime, int type)
 	}
 	attypes = growalloc(attypes, sizeof *attypes, timecnt, &timecnt_alloc);
 	attypes[timecnt].at = starttime;
+	attypes[timecnt].dontmerge = false;
 	attypes[timecnt].type = type;
 	++timecnt;
 }
@@ -2657,28 +2788,48 @@ adjleap(void)
 	}
 }
 
+static char *
+shellquote(char *b, char const *s)
+{
+  *b++ = '\'';
+  while (*s) {
+    if (*s == '\'')
+      *b++ = '\'', *b++ = '\\', *b++ = '\'';
+    *b++ = *s++;
+  }
+  *b++ = '\'';
+  return b;
+}
+
 static bool
-yearistype(int year, const char *type)
+yearistype(zic_t year, const char *type)
 {
-	static char *	buf;
-	int		result;
+	char *buf;
+	char *b;
+	int result;
 
 	if (type == NULL || *type == '\0')
 		return true;
-	buf = erealloc(buf, 132 + strlen(yitcommand) + strlen(type));
-	sprintf(buf, "%s %d %s", yitcommand, year, type);
+	buf = emalloc(1 + 4 * strlen(yitcommand) + 2
+		      + INT_STRLEN_MAXIMUM(zic_t) + 2 + 4 * strlen(type) + 2);
+	b = shellquote(buf, yitcommand);
+	*b++ = ' ';
+	b += sprintf(b, "%"PRIdZIC, year);
+	*b++ = ' ';
+	b = shellquote(b, type);
+	*b = '\0';
 	result = system(buf);
-	if (WIFEXITED(result)) switch (WEXITSTATUS(result)) {
-		case 0:
-			return true;
-		case 1:
-			return false;
+	if (WIFEXITED(result)) {
+	  int status = WEXITSTATUS(result);
+	  if (status <= 1) {
+	    free(buf);
+	    return status == 0;
+	  }
 	}
 	error(_("Wild result from command execution"));
 	fprintf(stderr, _("%s: command was '%s', result was %d\n"),
 		progname, buf, result);
-	for ( ; ; )
-		exit(EXIT_FAILURE);
+	exit(EXIT_FAILURE);
 }
 
 /* Is A a space character in the C locale?  */
@@ -2806,10 +2957,8 @@ getfields(register char *cp)
 				if (*dp != '\0')
 					++dp;
 				else {
-					error(_(
-						"Odd number of quotation marks"
-						));
-					exit(1);
+				  error(_("Odd number of quotation marks"));
+				  exit(EXIT_FAILURE);
 				}
 		} while (*cp && *cp != '#' && !is_space(*cp));
 		if (is_space(*cp))
@@ -2972,44 +3121,49 @@ mp = _("time zone abbreviation differs from POSIX standard");
 	charcnt += i;
 }
 
-static bool
-mkdirs(char *argname)
+/* Ensure that the directories of ARGNAME exist, by making any missing
+   ones.  If ANCESTORS, do this only for ARGNAME's ancestors; otherwise,
+   do it for ARGNAME too.  Exit with failure if there is trouble.
+   Do not consider an existing non-directory to be trouble.  */
+static void
+mkdirs(char const *argname, bool ancestors)
 {
 	register char *	name;
 	register char *	cp;
 
-	if (argname == NULL || *argname == '\0')
-		return true;
 	cp = name = ecpyalloc(argname);
-	while ((cp = strchr(cp + 1, '/')) != 0) {
-		*cp = '\0';
+
+	/* Do not mkdir a root directory, as it must exist.  */
 #ifdef HAVE_DOS_FILE_NAMES
-		/*
-		** DOS drive specifier?
-		*/
-		if (is_alpha(name[0]) && name[1] == ':' && name[2] == '\0') {
-				*cp = '/';
-				continue;
-		}
+	if (is_alpha(name[0]) && name[1] == ':')
+	  cp += 2;
 #endif
+	while (*cp == '/')
+	  cp++;
+
+	while (cp && ((cp = strchr(cp, '/')) || !ancestors)) {
+		if (cp)
+		  *cp = '\0';
 		/*
 		** Try to create it.  It's OK if creation fails because
 		** the directory already exists, perhaps because some
-		** other process just created it.
+		** other process just created it.  For simplicity do
+		** not check first whether it already exists, as that
+		** is checked anyway if the mkdir fails.
 		*/
 		if (mkdir(name, MKDIR_UMASK) != 0) {
+			/* For speed, skip itsdir if errno == EEXIST.  Since
+			   mkdirs is called only after open fails with ENOENT
+			   on a subfile, EEXIST implies itsdir here.  */
 			int err = errno;
-			if (itsdir(name) <= 0) {
-				char const *e = strerror(err);
-				warning(_("%s: Can't create directory"
-					  " %s: %s"),
-					progname, name, e);
-				free(name);
-				return false;
+			if (err != EEXIST && !itsdir(name)) {
+				error(_("%s: Can't create directory %s: %s"),
+				      progname, name, strerror(err));
+				exit(EXIT_FAILURE);
 			}
 		}
-		*cp = '/';
+		if (cp)
+		  *cp++ = '/';
 	}
 	free(name);
-	return true;
 }