Update timezone code from tzcode 2015g.

This patch updates the timezone code from tzcode 2015g.  The Makefile
and README changes are based on those in Paul's patch
<https://sourceware.org/ml/libc-alpha/2015-05/msg00553.html>.

Tested for x86_64 and x86.

2016-01-06  Paul Eggert  <eggert@cs.ucla.edu>
	    Joseph Myers  <joseph@codesourcery.com>

	* timezone/private.h: Update from tzcode 2015g.
	* timezone/tzfile.h: Likewise.
	* timezone/tzselect.ksh: Likewise.
	* timezone/zdump.c: Likewise.
	* timezone/zic.c: Likewise.
	* timezone/ialloc.c: Remove file.
	* timezone/scheck.c: Likewise.
	* timezone/Makefile (extra-objs): Remove variable.
	($(objpfx)zic): Do not depend on scheck.o and ialloc.o.
	(tz-cflags): Add -DHAVE_GETTEXT -DUSE_LTZ=0
	-Wno-maybe-uninitialized.
	(CFLAGS-zdump.c): Remove -fwrapv -DNOID -DHAVE_GETTEXT.
	(CFLAGS-zic.c): Remove -DNOID -DHAVE_GETTEXT.
	(CFLAGS-ialloc.c): Remove variable.
	(CFLAGS-scheck.c): Likewise.
	* timezone/README: Update list of files from tzcode.

10 files changed, 1476 insertions, 918 deletions

diff --git a/ChangeLog b/ChangeLog
index 67f21816bf..d7dd24bfc4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,23 @@
+2016-01-06  Paul Eggert  <eggert@cs.ucla.edu>
+	    Joseph Myers  <joseph@codesourcery.com>
+
+	* timezone/private.h: Update from tzcode 2015g.
+	* timezone/tzfile.h: Likewise.
+	* timezone/tzselect.ksh: Likewise.
+	* timezone/zdump.c: Likewise.
+	* timezone/zic.c: Likewise.
+	* timezone/ialloc.c: Remove file.
+	* timezone/scheck.c: Likewise.
+	* timezone/Makefile (extra-objs): Remove variable.
+	($(objpfx)zic): Do not depend on scheck.o and ialloc.o.
+	(tz-cflags): Add -DHAVE_GETTEXT -DUSE_LTZ=0
+	-Wno-maybe-uninitialized.
+	(CFLAGS-zdump.c): Remove -fwrapv -DNOID -DHAVE_GETTEXT.
+	(CFLAGS-zic.c): Remove -DNOID -DHAVE_GETTEXT.
+	(CFLAGS-ialloc.c): Remove variable.
+	(CFLAGS-scheck.c): Likewise.
+	* timezone/README: Update list of files from tzcode.
+
 2016-01-07  Khem Raj  <raj.khem@gmail.com>
 
 	* argp/argp-fmtstream.c (__argp_fmtstream_free): Use fwrite_unlocked
diff --git a/timezone/Makefile b/timezone/Makefile
index e929a5fd90..e6a6a088a2 100644
--- a/timezone/Makefile
+++ b/timezone/Makefile
@@ -22,8 +22,6 @@ subdir	:= timezone
 
 include ../Makeconfig
 
-extra-objs := scheck.o ialloc.o
-
 others	:= zdump zic
 tests	:= test-tz tst-timezone tst-tzset
 
@@ -49,8 +47,6 @@ endif
 include ../Rules
 
 
-$(objpfx)zic: $(objpfx)scheck.o $(objpfx)ialloc.o
-
 $(objpfx)zic.o $(objpfx)zdump.o: $(objpfx)version.h
 
 $(objpfx)version.h: $(common-objpfx)config.make
@@ -61,15 +57,14 @@ $(objpfx)version.h: $(common-objpfx)config.make
 tz-cflags = -DTZDIR='"$(zonedir)"' \
 	    -DTZDEFAULT='"$(localtime-file)"' \
 	    -DTZDEFRULES='"$(posixrules-file)"' \
-	    -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone
+	    -DTM_GMTOFF=tm_gmtoff -DTM_ZONE=tm_zone \
+	    -DHAVE_GETTEXT -DUSE_LTZ=0 -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
 # defined in private.h but not used.
-CFLAGS-zdump.c = -fwrapv -DNOID $(tz-cflags) -DHAVE_GETTEXT
-CFLAGS-zic.c = -DNOID $(tz-cflags) -DHAVE_GETTEXT -Wno-unused-variable
-CFLAGS-ialloc.c = -DNOID -DHAVE_GETTEXT -Wno-unused-variable
-CFLAGS-scheck.c = -DNOID -DHAVE_GETTEXT -Wno-unused-variable
+CFLAGS-zdump.c = $(tz-cflags)
+CFLAGS-zic.c = $(tz-cflags) -Wno-unused-variable
 
 # We have to make sure the data for testing the tz functions is available.
 # Don't add leapseconds here since test-tz made checks that work only without
diff --git a/timezone/README b/timezone/README
index 2268f8ec85..3251b12a81 100644
--- a/timezone/README
+++ b/timezone/README
@@ -1,5 +1,5 @@
 The files
-	zic.c zdump.c ialloc.c scheck.c tzfile.h
+	zic.c zdump.c tzfile.h
 	private.h tzselect.ksh checktab.awk
 come from the tzcode package by Arthur David Olson et.al.
 
diff --git a/timezone/ialloc.c b/timezone/ialloc.c
deleted file mode 100644
index b6f018897b..0000000000
--- a/timezone/ialloc.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
-*/
-
-/*LINTLIBRARY*/
-
-#include "private.h"
-
-char *
-icatalloc(char *const old, const char *const new)
-{
-	register char *	result;
-	register int	oldsize, newsize;
-
-	newsize = (new == NULL) ? 0 : strlen(new);
-	if (old == NULL)
-		oldsize = 0;
-	else if (newsize == 0)
-		return old;
-	else	oldsize = strlen(old);
-	if ((result = realloc(old, oldsize + newsize + 1)) != NULL)
-		if (new != NULL)
-			(void) strcpy(result + oldsize, new);
-	return result;
-}
-
-char *
-icpyalloc(const char *const string)
-{
-	return icatalloc(NULL, string);
-}
diff --git a/timezone/private.h b/timezone/private.h
index 4e8f4ae7bc..1c176e62bc 100644
--- a/timezone/private.h
+++ b/timezone/private.h
@@ -19,13 +19,9 @@
 
 /*
 ** Defaults for preprocessor symbols.
-** You can override these in your C compiler options, e.g. `-DHAVE_ADJTIME=0'.
+** You can override these in your C compiler options, e.g. '-DHAVE_GETTEXT=1'.
 */
 
-#ifndef HAVE_ADJTIME
-#define HAVE_ADJTIME		1
-#endif /* !defined HAVE_ADJTIME */
-
 #ifndef HAVE_GETTEXT
 #define HAVE_GETTEXT		0
 #endif /* !defined HAVE_GETTEXT */
@@ -38,9 +34,9 @@
 #define HAVE_LINK		1
 #endif /* !defined HAVE_LINK */
 
-#ifndef HAVE_SETTIMEOFDAY
-#define HAVE_SETTIMEOFDAY	3
-#endif /* !defined HAVE_SETTIMEOFDAY */
+#ifndef HAVE_STRDUP
+#define HAVE_STRDUP 1
+#endif
 
 #ifndef HAVE_SYMLINK
 #define HAVE_SYMLINK		1
@@ -59,30 +55,61 @@
 #endif /* !defined HAVE_UNISTD_H */
 
 #ifndef HAVE_UTMPX_H
-#define HAVE_UTMPX_H		0
+#define HAVE_UTMPX_H		1
 #endif /* !defined HAVE_UTMPX_H */
 
-#ifndef LOCALE_HOME
-#define LOCALE_HOME		"/usr/lib/locale"
-#endif /* !defined LOCALE_HOME */
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
 
 #if HAVE_INCOMPATIBLE_CTIME_R
 #define asctime_r _incompatible_asctime_r
 #define ctime_r _incompatible_ctime_r
 #endif /* HAVE_INCOMPATIBLE_CTIME_R */
 
+/* Enable tm_gmtoff and tm_zone on GNUish systems.  */
+#define _GNU_SOURCE 1
+/* Fix asctime_r on Solaris 10.  */
+#define _POSIX_PTHREAD_SEMANTICS 1
+/* Enable strtoimax on Solaris 10.  */
+#define __EXTENSIONS__ 1
+
 /*
 ** Nested includes
 */
 
+/* Avoid clashes with NetBSD by renaming NetBSD's declarations.  */
+#define localtime_rz sys_localtime_rz
+#define mktime_z sys_mktime_z
+#define posix2time_z sys_posix2time_z
+#define time2posix_z sys_time2posix_z
+#define timezone_t sys_timezone_t
+#define tzalloc sys_tzalloc
+#define tzfree sys_tzfree
+#include <time.h>
+#undef localtime_rz
+#undef mktime_z
+#undef posix2time_z
+#undef time2posix_z
+#undef timezone_t
+#undef tzalloc
+#undef tzfree
+
 #include "sys/types.h"	/* for time_t */
 #include "stdio.h"
-#include "errno.h"
 #include "string.h"
 #include "limits.h"	/* for CHAR_BIT et al. */
-#include "time.h"
 #include "stdlib.h"
 
+#include "errno.h"
+
+#ifndef ENAMETOOLONG
+# define ENAMETOOLONG EINVAL
+#endif
+#ifndef EOVERFLOW
+# define EOVERFLOW EINVAL
+#endif
+
 #if HAVE_GETTEXT
 #include "libintl.h"
 #endif /* HAVE_GETTEXT */
@@ -102,6 +129,14 @@
 #include "unistd.h"	/* for F_OK, R_OK, and other POSIX goodness */
 #endif /* HAVE_UNISTD_H */
 
+#ifndef HAVE_STRFTIME_L
+# if _POSIX_VERSION < 200809
+#  define HAVE_STRFTIME_L 0
+# else
+#  define HAVE_STRFTIME_L 1
+# endif
+#endif
+
 #ifndef F_OK
 #define F_OK	0
 #endif /* !defined F_OK */
@@ -136,65 +171,98 @@
 # include <inttypes.h>
 #endif
 
-#ifndef INT_FAST64_MAX
 /* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
-#if defined LLONG_MAX || defined __LONG_LONG_MAX__
-typedef long long	int_fast64_t;
+#ifdef __LONG_LONG_MAX__
+# ifndef LLONG_MAX
+#  define LLONG_MAX __LONG_LONG_MAX__
+# endif
+# ifndef LLONG_MIN
+#  define LLONG_MIN (-1 - LLONG_MAX)
+# endif
+#endif
+
+#ifndef INT_FAST64_MAX
 # ifdef LLONG_MAX
+typedef long long	int_fast64_t;
 #  define INT_FAST64_MIN LLONG_MIN
 #  define INT_FAST64_MAX LLONG_MAX
 # else
-#  define INT_FAST64_MIN __LONG_LONG_MIN__
-#  define INT_FAST64_MAX __LONG_LONG_MAX__
-# endif
-# define SCNdFAST64 "lld"
-#else /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#if (LONG_MAX >> 31) < 0xffffffff
+#  if LONG_MAX >> 31 < 0xffffffff
 Please use a compiler that supports a 64-bit integer type (or wider);
 you may need to compile with "-DHAVE_STDINT_H".
-#endif /* (LONG_MAX >> 31) < 0xffffffff */
+#  endif
 typedef long		int_fast64_t;
-# define INT_FAST64_MIN LONG_MIN
-# define INT_FAST64_MAX LONG_MAX
-# define SCNdFAST64 "ld"
-#endif /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
-#endif /* !defined INT_FAST64_MAX */
+#  define INT_FAST64_MIN LONG_MIN
+#  define INT_FAST64_MAX LONG_MAX
+# endif
+#endif
+
+#ifndef SCNdFAST64
+# if INT_FAST64_MAX == LLONG_MAX
+#  define SCNdFAST64 "lld"
+# else
+#  define SCNdFAST64 "ld"
+# endif
+#endif
 
 #ifndef INT_FAST32_MAX
 # if INT_MAX >> 31 == 0
 typedef long int_fast32_t;
+#  define INT_FAST32_MAX LONG_MAX
+#  define INT_FAST32_MIN LONG_MIN
 # else
 typedef int int_fast32_t;
+#  define INT_FAST32_MAX INT_MAX
+#  define INT_FAST32_MIN INT_MIN
 # endif
 #endif
 
 #ifndef INTMAX_MAX
-# if defined LLONG_MAX || defined __LONG_LONG_MAX__
+# ifdef LLONG_MAX
 typedef long long intmax_t;
 #  define strtoimax strtoll
-#  define PRIdMAX "lld"
-#  ifdef LLONG_MAX
-#   define INTMAX_MAX LLONG_MAX
-#   define INTMAX_MIN LLONG_MIN
-#  else
-#   define INTMAX_MAX __LONG_LONG_MAX__
-#   define INTMAX_MIN __LONG_LONG_MIN__
-#  endif
+#  define INTMAX_MAX LLONG_MAX
+#  define INTMAX_MIN LLONG_MIN
 # else
 typedef long intmax_t;
 #  define strtoimax strtol
-#  define PRIdMAX "ld"
 #  define INTMAX_MAX LONG_MAX
 #  define INTMAX_MIN LONG_MIN
 # endif
 #endif
 
+#ifndef PRIdMAX
+# if INTMAX_MAX == LLONG_MAX
+#  define PRIdMAX "lld"
+# else
+#  define PRIdMAX "ld"
+# endif
+#endif
+
+#ifndef UINT_FAST64_MAX
+# if defined ULLONG_MAX || defined __LONG_LONG_MAX__
+typedef unsigned long long uint_fast64_t;
+# else
+#  if ULONG_MAX >> 31 >> 1 < 0xffffffff
+Please use a compiler that supports a 64-bit integer type (or wider);
+you may need to compile with "-DHAVE_STDINT_H".
+#  endif
+typedef unsigned long	uint_fast64_t;
+# endif
+#endif
+
 #ifndef UINTMAX_MAX
 # if defined ULLONG_MAX || defined __LONG_LONG_MAX__
 typedef unsigned long long uintmax_t;
-#  define PRIuMAX "llu"
 # else
 typedef unsigned long uintmax_t;
+# endif
+#endif
+
+#ifndef PRIuMAX
+# if defined ULLONG_MAX || defined __LONG_LONG_MAX__
+#  define PRIuMAX "llu"
+# else
 #  define PRIuMAX "lu"
 # endif
 #endif
@@ -237,16 +305,6 @@ typedef unsigned long uintmax_t;
 */
 
 /*
-** Some time.h implementations don't declare asctime_r.
-** Others might define it as a macro.
-** Fix the former without affecting the latter.
-*/
-
-#ifndef asctime_r
-extern char *	asctime_r(struct tm const *, char *);
-#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
@@ -254,7 +312,11 @@ extern char *	asctime_r(struct tm const *, char *);
 ** typical platforms.
 */
 #ifdef time_tz
+# ifdef LOCALTIME_IMPLEMENTATION
 static time_t sys_time(time_t *x) { return time(x); }
+# endif
+
+typedef time_tz tz_time_t;
 
 # undef  ctime
 # define ctime tz_ctime
@@ -270,14 +332,40 @@ static time_t sys_time(time_t *x) { return time(x); }
 # define localtime tz_localtime
 # undef  localtime_r
 # define localtime_r tz_localtime_r
+# undef  localtime_rz
+# define localtime_rz tz_localtime_rz
 # undef  mktime
 # define mktime tz_mktime
+# undef  mktime_z
+# define mktime_z tz_mktime_z
+# undef  offtime
+# define offtime tz_offtime
+# undef  posix2time
+# define posix2time tz_posix2time
+# undef  posix2time_z
+# define posix2time_z tz_posix2time_z
 # undef  time
 # define time tz_time
+# undef  time2posix
+# define time2posix tz_time2posix
+# undef  time2posix_z
+# define time2posix_z tz_time2posix_z
 # undef  time_t
 # define time_t tz_time_t
-
-typedef time_tz time_t;
+# undef  timegm
+# define timegm tz_timegm
+# undef  timelocal
+# define timelocal tz_timelocal
+# undef  timeoff
+# define timeoff tz_timeoff
+# undef  tzalloc
+# define tzalloc tz_tzalloc
+# undef  tzfree
+# define tzfree tz_tzfree
+# undef  tzset
+# define tzset tz_tzset
+# undef  tzsetwall
+# define tzsetwall tz_tzsetwall
 
 char *ctime(time_t const *);
 char *ctime_r(time_t const *, char *);
@@ -287,36 +375,111 @@ struct tm *gmtime_r(time_t const *restrict, struct tm *restrict);
 struct tm *localtime(time_t const *);
 struct tm *localtime_r(time_t const *restrict, struct tm *restrict);
 time_t mktime(struct tm *);
+time_t time(time_t *);
+void tzset(void);
+#endif
+
+/*
+** 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);
+#endif
 
-static time_t
-time(time_t *p)
-{
-	time_t r = sys_time(0);
-	if (p)
-		*p = r;
-	return r;
-}
+#ifdef USG_COMPAT
+# ifndef timezone
+extern long timezone;
+# endif
+# ifndef daylight
+extern int daylight;
+# endif
+#endif
+#if defined ALTZONE && !defined altzone
+extern long altzone;
 #endif
 
 /*
-** Private function declarations.
+** The STD_INSPIRED functions are similar, but most also need
+** declarations if time_tz is defined.
 */
 
-char *		icatalloc(char * old, const char * new);
-char *		icpyalloc(const char * string);
-const char *	scheck(const char * string, const char * format);
+#ifdef STD_INSPIRED
+# if !defined tzsetwall || defined time_tz
+void tzsetwall(void);
+# endif
+# if !defined offtime || defined time_tz
+struct tm *offtime(time_t const *, long);
+# endif
+# if !defined timegm || defined time_tz
+time_t timegm(struct tm *);
+# endif
+# if !defined timelocal || defined time_tz
+time_t timelocal(struct tm *);
+# endif
+# if !defined timeoff || defined time_tz
+time_t timeoff(struct tm *, long);
+# endif
+# if !defined time2posix || defined time_tz
+time_t time2posix(time_t);
+# endif
+# if !defined posix2time || defined time_tz
+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
 
 /*
-** Finally, some convenience items.
+** 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 !defined posix2time_z || defined time_tz
+time_t posix2time_z(timezone_t, time_t) ATTRIBUTE_PURE;
+#  endif
+#  if !defined time2posix_z || defined time_tz
+time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_PURE;
+#  endif
+# endif
+#endif
 
-#ifndef TRUE
-#define TRUE	1
-#endif /* !defined TRUE */
+/*
+** Finally, some convenience items.
+*/
 
-#ifndef FALSE
-#define FALSE	0
-#endif /* !defined FALSE */
+#if __STDC_VERSION__ < 199901
+# define true 1
+# define false 0
+# define bool int
+#else
+# include <stdbool.h>
+#endif
 
 #ifndef TYPE_BIT
 #define TYPE_BIT(type)	(sizeof (type) * CHAR_BIT)
@@ -326,15 +489,20 @@ const char *	scheck(const char * string, const char * format);
 #define TYPE_SIGNED(type) (((type) -1) < 0)
 #endif /* !defined TYPE_SIGNED */
 
-/* The minimum and maximum finite time values.  */
-static time_t const time_t_min =
-  (TYPE_SIGNED(time_t)
-   ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
-   : 0);
-static time_t const time_t_max =
-  (TYPE_SIGNED(time_t)
-   ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
-   : -1);
+#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 minimum and maximum finite time values.  This assumes no padding.  */
+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));
 
 #ifndef INT_STRLEN_MAXIMUM
 /*
@@ -352,29 +520,19 @@ static time_t const time_t_max =
 ** INITIALIZE(x)
 */
 
-#ifndef GNUC_or_lint
 #ifdef lint
-#define GNUC_or_lint
-#endif /* defined lint */
-#ifndef lint
-#ifdef __GNUC__
-#define GNUC_or_lint
-#endif /* defined __GNUC__ */
-#endif /* !defined lint */
-#endif /* !defined GNUC_or_lint */
-
-#ifndef INITIALIZE
-#ifdef GNUC_or_lint
-#define INITIALIZE(x)	((x) = 0)
-#endif /* defined GNUC_or_lint */
-#ifndef GNUC_or_lint
-#define INITIALIZE(x)
-#endif /* !defined GNUC_or_lint */
-#endif /* !defined INITIALIZE */
+# define INITIALIZE(x)	((x) = 0)
+#else
+# define INITIALIZE(x)
+#endif
+
+#ifndef UNINIT_TRAP
+# define UNINIT_TRAP 0
+#endif
 
 /*
 ** For the benefit of GNU folk...
-** `_(MSGID)' uses the current locale's message library string for MSGID.
+** '_(MSGID)' uses the current locale's message library string for MSGID.
 ** The default is to use gettext if available, and use MSGID otherwise.
 */
 
@@ -386,9 +544,9 @@ static time_t const time_t_max =
 #endif /* !HAVE_GETTEXT */
 #endif /* !defined _ */
 
-#ifndef TZ_DOMAIN
-#define TZ_DOMAIN "tz"
-#endif /* !defined TZ_DOMAIN */
+#if !defined TZ_DOMAIN && defined HAVE_GETTEXT
+# define TZ_DOMAIN "tz"
+#endif
 
 #if HAVE_INCOMPATIBLE_CTIME_R
 #undef asctime_r
@@ -417,8 +575,4 @@ char *ctime_r(time_t const *, char *);
 #define SECSPERREPEAT_BITS	34	/* ceil(log2(SECSPERREPEAT)) */
 #endif /* !defined SECSPERREPEAT_BITS */
 
-/*
-** UNIX was a registered trademark of The Open Group in 2003.
-*/
-
 #endif /* !defined PRIVATE_H */
diff --git a/timezone/scheck.c b/timezone/scheck.c
deleted file mode 100644
index 8bd01a858f..0000000000
--- a/timezone/scheck.c
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
-*/
-
-/*LINTLIBRARY*/
-
-#include "private.h"
-
-const char *
-scheck(const char *const string, const char *const format)
-{
-	register char *		fbuf;
-	register const char *	fp;
-	register char *		tp;
-	register int		c;
-	register const char *	result;
-	char			dummy;
-
-	result = "";
-	if (string == NULL || format == NULL)
-		return result;
-	fbuf = malloc(2 * strlen(format) + 4);
-	if (fbuf == NULL)
-		return result;
-	fp = format;
-	tp = fbuf;
-
-	/*
-	** Copy directives, suppressing each conversion that is not
-	** already suppressed.  Scansets containing '%' are not
-	** supported; e.g., the conversion specification "%[%]" is not
-	** supported.  Also, multibyte characters containing a
-	** non-leading '%' byte are not supported.
-	*/
-	while ((*tp++ = c = *fp++) != '\0') {
-		if (c != '%')
-			continue;
-		if (is_digit(*fp)) {
-			char const *f = fp;
-			char *t = tp;
-			do {
-				*t++ = c = *f++;
-			} while (is_digit(c));
-			if (c == '$') {
-				fp = f;
-				tp = t;
-			}
-		}
-		*tp++ = '*';
-		if (*fp == '*')
-			++fp;
-		if ((*tp++ = *fp++) == '\0')
-			break;
-	}
-
-	*(tp - 1) = '%';
-	*tp++ = 'c';
-	*tp = '\0';
-	if (sscanf(string, fbuf, &dummy) != 1)
-		result = format;
-	free(fbuf);
-	return result;
-}
diff --git a/timezone/tzfile.h b/timezone/tzfile.h
index 911130eb93..ebecd68322 100644
--- a/timezone/tzfile.h
+++ b/timezone/tzfile.h
@@ -40,7 +40,7 @@
 struct tzhead {
 	char	tzh_magic[4];		/* TZ_MAGIC */
 	char	tzh_version[1];		/* '\0' or '2' or '3' as of 2013 */
-	char	tzh_reserved[15];	/* reserved--must be zero */
+	char	tzh_reserved[15];	/* reserved; must be zero */
 	char	tzh_ttisgmtcnt[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 */
@@ -62,13 +62,13 @@ struct tzhead {
 **	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 TRUE, transition
-**					time is standard time, if FALSE,
+**	tzh_ttisstdcnt (char)s		indexed by type; if 1, transition
+**					time is standard time, if 0,
 **					transition time is wall clock time
 **					if absent, transition times are
 **					assumed to be wall clock time
-**	tzh_ttisgmtcnt (char)s		indexed by type; if TRUE, transition
-**					time is UT, if FALSE,
+**	tzh_ttisgmtcnt (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
diff --git a/timezone/tzselect.ksh b/timezone/tzselect.ksh
index 9d7069116a..2c3b2f4438 100755
--- a/timezone/tzselect.ksh
+++ b/timezone/tzselect.ksh
@@ -37,15 +37,22 @@ REPORT_BUGS_TO=tz@iana.org
 : ${AWK=awk}
 : ${TZDIR=`pwd`}
 
+# Output one argument as-is to standard output.
+# Safer than 'echo', which can mishandle '\' or leading '-'.
+say() {
+    printf '%s\n' "$1"
+}
+
 # Check for awk Posix compliance.
 ($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
 [ $? = 123 ] || {
-	echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
+	say >&2 "$0: Sorry, your '$AWK' program is not Posix compatible."
 	exit 1
 }
 
 coord=
 location_limit=10
+zonetabtype=zone1970
 
 usage="Usage: tzselect [--version] [--help] [-c COORD] [-n LIMIT]
 Select a time zone interactively.
@@ -80,7 +87,7 @@ if
   ?*) : ;;
   '')
     # '; exit' should be redundant, but Dash doesn't properly fail without it.
-    (eval 'set --; select x; do break; done; exit') 2>/dev/null
+    (eval 'set --; select x; do break; done; exit') </dev/null 2>/dev/null
   esac
 then
   # Do this inside 'eval', as otherwise the shell might exit when parsing it
@@ -139,41 +146,58 @@ else
   }
 fi
 
-while getopts c:n:-: opt
+while getopts c:n:t:-: opt
 do
     case $opt$OPTARG in
     c*)
 	coord=$OPTARG ;;
     n*)
 	location_limit=$OPTARG ;;
+    t*) # Undocumented option, used for developer testing.
+	zonetabtype=$OPTARG ;;
     -help)
 	exec echo "$usage" ;;
     -version)
 	exec echo "tzselect $PKGVERSION$TZVERSION" ;;
     -*)
-	echo >&2 "$0: -$opt$OPTARG: unknown option; try '$0 --help'"; exit 1 ;;
+	say >&2 "$0: -$opt$OPTARG: unknown option; try '$0 --help'"; exit 1 ;;
     *)
-	echo >&2 "$0: try '$0 --help'"; exit 1 ;;
+	say >&2 "$0: try '$0 --help'"; exit 1 ;;
     esac
 done
 
 shift `expr $OPTIND - 1`
 case $# in
 0) ;;
-*) echo >&2 "$0: $1: unknown argument"; exit 1 ;;
+*) say >&2 "$0: $1: unknown argument"; exit 1 ;;
 esac
 
 # Make sure the tables are readable.
 TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
-TZ_ZONE_TABLE=$TZDIR/zone.tab
+TZ_ZONE_TABLE=$TZDIR/$zonetabtype.tab
 for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
 do
-	<$f || {
-		echo >&2 "$0: time zone files are not set up correctly"
+	<"$f" || {
+		say >&2 "$0: time zone files are not set up correctly"
 		exit 1
 	}
 done
 
+# If the current locale does not support UTF-8, convert data to current
+# locale's format if possible, as the shell aligns columns better that way.
+# Check the UTF-8 of U+12345 CUNEIFORM SIGN URU TIMES KI.
+! $AWK 'BEGIN { u12345 = "\360\222\215\205"; exit length(u12345) != 1 }' &&
+    { tmp=`(mktemp -d) 2>/dev/null` || {
+	tmp=${TMPDIR-/tmp}/tzselect.$$ &&
+	(umask 77 && mkdir -- "$tmp")
+    };} &&
+    trap 'status=$?; rm -fr -- "$tmp"; exit $status' 0 HUP INT PIPE TERM &&
+    (iconv -f UTF-8 -t //TRANSLIT <"$TZ_COUNTRY_TABLE" >$tmp/iso3166.tab) \
+        2>/dev/null &&
+    TZ_COUNTRY_TABLE=$tmp/iso3166.tab &&
+    iconv -f UTF-8 -t //TRANSLIT <"$TZ_ZONE_TABLE" >$tmp/$zonetabtype.tab &&
+    TZ_ZONE_TABLE=$tmp/$zonetabtype.tab
+
 newline='
 '
 IFS=$newline
@@ -189,7 +213,13 @@ output_distances='
         country[$1] = $2
     country["US"] = "US" # Otherwise the strings get too long.
   }
-  function convert_coord(coord, deg, min, ilen, sign, sec) {
+  function abs(x) {
+    return x < 0 ? -x : x;
+  }
+  function min(x, y) {
+    return x < y ? x : y;
+  }
+  function convert_coord(coord, deg, minute, ilen, sign, sec) {
     if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9][0-9][0-9]([^0-9]|$)/) {
       degminsec = coord
       intdeg = degminsec < 0 ? -int(-degminsec / 10000) : int(degminsec / 10000)
@@ -200,8 +230,8 @@ output_distances='
     } else if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9]([^0-9]|$)/) {
       degmin = coord
       intdeg = degmin < 0 ? -int(-degmin / 100) : int(degmin / 100)
-      min = degmin - intdeg * 100
-      deg = (intdeg * 60 + min) / 60
+      minute = degmin - intdeg * 100
+      deg = (intdeg * 60 + minute) / 60
     } else
       deg = coord
     return deg * 0.017453292519943296
@@ -217,14 +247,27 @@ output_distances='
   # Great-circle distance between points with given latitude and longitude.
   # Inputs and output are in radians.  This uses the great-circle special
   # case of the Vicenty formula for distances on ellipsoids.
-  function dist(lat1, long1, lat2, long2, dlong, x, y, num, denom) {
+  function gcdist(lat1, long1, lat2, long2, dlong, x, y, num, denom) {
     dlong = long2 - long1
-    x = cos (lat2) * sin (dlong)
-    y = cos (lat1) * sin (lat2) - sin (lat1) * cos (lat2) * cos (dlong)
-    num = sqrt (x * x + y * y)
-    denom = sin (lat1) * sin (lat2) + cos (lat1) * cos (lat2) * cos (dlong)
+    x = cos(lat2) * sin(dlong)
+    y = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dlong)
+    num = sqrt(x * x + y * y)
+    denom = sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(dlong)
     return atan2(num, denom)
   }
+  # Parallel distance between points with given latitude and longitude.
+  # This is the product of the longitude difference and the cosine
+  # of the latitude of the point that is further from the equator.
+  # I.e., it considers longitudes to be further apart if they are
+  # nearer the equator.
+  function pardist(lat1, long1, lat2, long2) {
+    return abs(long1 - long2) * min(cos(lat1), cos(lat2))
+  }
+  # The distance function is the sum of the great-circle distance and
+  # the parallel distance.  It could be weighted.
+  function dist(lat1, long1, lat2, long2) {
+    return gcdist(lat1, long1, lat2, long2) + pardist(lat1, long1, lat2, long2)
+  }
   BEGIN {
     coord_lat = convert_latitude(coord)
     coord_long = convert_longitude(coord)
@@ -232,7 +275,13 @@ output_distances='
   /^[^#]/ {
     here_lat = convert_latitude($2)
     here_long = convert_longitude($2)
-    line = $1 "\t" $2 "\t" $3 "\t" country[$1]
+    line = $1 "\t" $2 "\t" $3
+    sep = "\t"
+    ncc = split($1, cc, /,/)
+    for (i = 1; i <= ncc; i++) {
+      line = line sep country[cc[i]]
+      sep = ", "
+    }
     if (NF == 4)
       line = line " - " $4
     printf "%g\t%s\n", dist(coord_lat, coord_long, here_lat, here_long), line
@@ -269,7 +318,7 @@ while
 		entry = entry " Ocean"
               printf "'\''%s'\''\n", entry
             }
-          ' $TZ_ZONE_TABLE |
+          ' <"$TZ_ZONE_TABLE" |
 	  sort -u |
 	  tr '\n' ' '
 	  echo ''
@@ -300,7 +349,7 @@ while
 				tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
 				time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
 				offset = "[-+]?" time
-				date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
+				date = "(J?[0-9]+|M[0-9]+\\.[0-9]+\\.[0-9]+)"
 				datetime = "," date "(/" time ")?"
 				tzpattern = "^(:.*|" tzname offset "(" tzname \
 				  "(" offset ")?(" datetime datetime ")?)?)$"
@@ -308,8 +357,7 @@ while
 				exit 0
 			}'
 		do
-			echo >&2 "\`$TZ' is not a conforming" \
-				'Posix time zone string.'
+		    say >&2 "'$TZ' is not a conforming Posix time zone string."
 		done
 		TZ_for_date=$TZ;;
 	*)
@@ -327,11 +375,11 @@ while
 		    distance_table=`$AWK \
 			    -v coord="$coord" \
 			    -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
-			    "$output_distances" <$TZ_ZONE_TABLE |
+			    "$output_distances" <"$TZ_ZONE_TABLE" |
 		      sort -n |
 		      sed "${location_limit}q"
 		    `
-		    regions=`echo "$distance_table" | $AWK '
+		    regions=`say "$distance_table" | $AWK '
 		      BEGIN { FS = "\t" }
 		      { print $NF }
 		    '`
@@ -341,7 +389,7 @@ while
 			    "of distance from $coord".
 		    doselect $regions
 		    region=$select_result
-		    TZ=`echo "$distance_table" | $AWK -v region="$region" '
+		    TZ=`say "$distance_table" | $AWK -v region="$region" '
 		      BEGIN { FS="\t" }
 		      $NF == region { print $4 }
 		    '`
@@ -355,7 +403,9 @@ while
 			BEGIN { FS = "\t" }
 			/^#/ { next }
 			$3 ~ ("^" continent "/") {
-				if (!cc_seen[$1]++) cc_list[++ccs] = $1
+			    ncc = split($1, cc, /,/)
+			    for (i = 1; i <= ncc; i++)
+				if (!cc_seen[cc[i]]++) cc_list[++ccs] = cc[i]
 			}
 			END {
 				while (getline <TZ_COUNTRY_TABLE) {
@@ -369,7 +419,7 @@ while
 					print country
 				}
 			}
-		' <$TZ_ZONE_TABLE | sort -f`
+		' <"$TZ_ZONE_TABLE" | sort -f`
 
 
 		# If there's more than one country, ask the user which one.
@@ -399,8 +449,9 @@ while
 					}
 				}
 			}
-			$1 == cc { print $4 }
-		' <$TZ_ZONE_TABLE`
+			/^#/ { next }
+			$1 ~ cc { print $4 }
+		' <"$TZ_ZONE_TABLE"`
 
 
 		# If there's more than one region, ask the user which one.
@@ -430,14 +481,15 @@ while
 					}
 				}
 			}
-			$1 == cc && $4 == region { print $3 }
-		' <$TZ_ZONE_TABLE`
+			/^#/ { next }
+			$1 ~ cc && $4 == region { print $3 }
+		' <"$TZ_ZONE_TABLE"`
 		esac
 
 		# Make sure the corresponding zoneinfo file exists.
 		TZ_for_date=$TZDIR/$TZ
-		<$TZ_for_date || {
-			echo >&2 "$0: time zone files are not set up correctly"
+		<"$TZ_for_date" || {
+			say >&2 "$0: time zone files are not set up correctly"
 			exit 1
 		}
 	esac
@@ -470,15 +522,15 @@ Universal Time is now:	$UTdate."
 	echo >&2 "The following information has been given:"
 	echo >&2 ""
 	case $country%$region%$coord in
-	?*%?*%)	echo >&2 "	$country$newline	$region";;
-	?*%%)	echo >&2 "	$country";;
-	%?*%?*) echo >&2 "	coord $coord$newline	$region";;
-	%%?*)	echo >&2 "	coord $coord";;
-	+)	echo >&2 "	TZ='$TZ'"
+	?*%?*%)	say >&2 "	$country$newline	$region";;
+	?*%%)	say >&2 "	$country";;
+	%?*%?*) say >&2 "	coord $coord$newline	$region";;
+	%%?*)	say >&2 "	coord $coord";;
+	*)	say >&2 "	TZ='$TZ'"
 	esac
-	echo >&2 ""
-	echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
-	echo >&2 "Is the above information OK?"
+	say >&2 ""
+	say >&2 "Therefore TZ='$TZ' will be used.$extra_info"
+	say >&2 "Is the above information OK?"
 
 	doselect Yes No
 	ok=$select_result
@@ -493,7 +545,7 @@ case $SHELL in
 *) file=.profile line="TZ='$TZ'; export TZ"
 esac
 
-echo >&2 "
+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.
@@ -501,4 +553,4 @@ to the file '$file' in your home directory; then log out and log in again.
 Here is that TZ value again, this time on standard output so that you
 can use the $0 command in shell scripts:"
 
-echo "$TZ"
+say "$TZ"
diff --git a/timezone/zdump.c b/timezone/zdump.c
index c48ac8435f..063a2635ec 100644
--- a/timezone/zdump.c
+++ b/timezone/zdump.c
@@ -9,25 +9,32 @@
 ** This code has been made independent of the rest of the time
 ** conversion package to increase confidence in the verification it provides.
 ** You can use this code to help in verifying other implementations.
-**
-** However, include private.h when debugging, so that it overrides
-** time_t consistently with the rest of the package.
+** To do this, compile with -DUSE_LTZ=0 and link without the tz library.
 */
 
-#ifdef time_tz
+#ifndef NETBSD_INSPIRED
+# define NETBSD_INSPIRED 1
+#endif
+#ifndef USE_LTZ
+# 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 "ctype.h"	/* for isalpha et al. */
-#ifndef isascii
-#define isascii(x) 1
-#endif /* !defined isascii */
+#include <errno.h>
 
 /*
 ** Substitutes for pre-C99 compilers.
@@ -58,24 +65,59 @@ 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
-# if defined LLONG_MAX || defined __LONG_LONG_MAX__
+# ifdef LLONG_MAX
 typedef long long intmax_t;
 #  define strtoimax strtoll
-#  define PRIdMAX "lld"
-#  ifdef LLONG_MAX
-#   define INTMAX_MAX LLONG_MAX
-#  else
-#   define INTMAX_MAX __LONG_LONG_MAX__
-#  endif
+#  define INTMAX_MAX LLONG_MAX
 # else
 typedef long intmax_t;
 #  define strtoimax strtol
-#  define PRIdMAX "ld"
 #  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
+
+#ifndef HAVE_LOCALTIME_R
+# define HAVE_LOCALTIME_R 1
+#endif
+
+#ifndef HAVE_LOCALTIME_RZ
+# ifdef TM_ZONE
+#  define HAVE_LOCALTIME_RZ (NETBSD_INSPIRED && USE_LTZ)
+# else
+#  define HAVE_LOCALTIME_RZ 0
+# endif
+#endif
+
+#ifndef HAVE_TZSET
+# define HAVE_TZSET 1
+#endif
 
 #ifndef ZDUMP_LO_YEAR
 #define ZDUMP_LO_YEAR	(-500)
@@ -89,13 +131,13 @@ typedef long intmax_t;
 #define MAX_STRING_LENGTH	1024
 #endif /* !defined MAX_STRING_LENGTH */
 
-#ifndef TRUE
-#define TRUE		1
-#endif /* !defined TRUE */
-
-#ifndef FALSE
-#define FALSE		0
-#endif /* !defined FALSE */
+#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
@@ -167,16 +209,6 @@ enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
 #include "libintl.h"
 #endif /* HAVE_GETTEXT */
 
-#ifndef GNUC_or_lint
-#ifdef lint
-#define GNUC_or_lint
-#else /* !defined lint */
-#ifdef __GNUC__
-#define GNUC_or_lint
-#endif /* defined __GNUC__ */
-#endif /* !defined lint */
-#endif /* !defined GNUC_or_lint */
-
 #if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
 # define ATTRIBUTE_PURE __attribute__ ((__pure__))
 #else
@@ -185,7 +217,7 @@ enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
 
 /*
 ** For the benefit of GNU folk...
-** `_(MSGID)' uses the current locale's message library string for MSGID.
+** '_(MSGID)' uses the current locale's message library string for MSGID.
 ** The default is to use gettext if available, and use MSGID otherwise.
 */
 
@@ -197,9 +229,14 @@ enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
 #endif /* !HAVE_GETTEXT */
 #endif /* !defined _ */
 
-#ifndef TZ_DOMAIN
-#define TZ_DOMAIN "tz"
-#endif /* !defined TZ_DOMAIN */
+#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;
 extern int	getopt(int argc, char * const argv[],
@@ -209,57 +246,233 @@ extern int	optind;
 extern char *	tzname[2];
 
 /* The minimum and maximum finite time values.  */
+enum { atime_shift = CHAR_BIT * sizeof (time_t) - 2 };
 static time_t const absolute_min_time =
   ((time_t) -1 < 0
-   ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
+   ? (- ((time_t) ~ (time_t) 0 < 0)
+      - (((time_t) 1 << atime_shift) - 1 + ((time_t) 1 << atime_shift)))
    : 0);
 static time_t const absolute_max_time =
   ((time_t) -1 < 0
-   ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
+   ? (((time_t) 1 << atime_shift) - 1 + ((time_t) 1 << atime_shift))
    : -1);
-static size_t	longest;
+static int	longest;
 static char *	progname;
-static int	warned;
+static bool	warned;
+static bool	errout;
+
+static char const *abbr(struct tm const *);
+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 const char *tformat(void);
+static time_t yeartot(intmax_t) ATTRIBUTE_PURE;
+
+/* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
+#define is_digit(c) ((unsigned)(c) - '0' <= 9)
+
+/* Is A an alphabetic character in the C locale?  */
+static bool
+is_alpha(char a)
+{
+	switch (a) {
+	  default:
+		return false;
+	  case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
+	  case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
+	  case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
+	  case 'V': case 'W': case 'X': case 'Y': case 'Z':
+	  case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
+	  case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
+	  case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
+	  case 'v': case 'w': case 'x': case 'y': case 'z':
+		return true;
+	}
+}
+
+/* Return A + B, exiting if the result would overflow.  */
+static size_t
+sumsize(size_t a, size_t b)
+{
+  size_t sum = a + b;
+  if (sum < a) {
+    fprintf(stderr, "%s: size overflow\n", progname);
+    exit(EXIT_FAILURE);
+  }
+  return sum;
+}
+
+#if ! HAVE_TZSET
+# undef tzset
+# define tzset zdump_tzset
+static void tzset(void) { }
+#endif
+
+/* Assume gmtime_r works if localtime_r does.
+   A replacement localtime_r is defined below if needed.  */
+#if ! HAVE_LOCALTIME_R
+
+# undef gmtime_r
+# define gmtime_r zdump_gmtime_r
+
+static struct tm *
+gmtime_r(time_t *tp, struct tm *tmp)
+{
+  struct tm *r = gmtime(tp);
+  if (r) {
+    *tmp = *r;
+    r = tmp;
+  }
+  return r;
+}
+
+#endif
+
+/* Platforms with TM_ZONE don't need tzname, so they can use the
+   faster localtime_rz or localtime_r if available.  */
+
+#if defined TM_ZONE && HAVE_LOCALTIME_RZ
+# define USE_LOCALTIME_RZ true
+#else
+# define USE_LOCALTIME_RZ false
+#endif
 
-static char *	abbr(struct tm * tmp);
-static void	abbrok(const char * abbrp, const char * zone);
-static intmax_t	delta(struct tm * newp, struct tm * oldp) ATTRIBUTE_PURE;
-static void	dumptime(const struct tm * tmp);
-static time_t	hunt(char * name, time_t lot, time_t	hit);
-static void	show(char * zone, time_t t, int v);
-static const char *	tformat(void);
-static time_t	yeartot(intmax_t y) ATTRIBUTE_PURE;
+#if ! USE_LOCALTIME_RZ
+
+# if !defined TM_ZONE || ! HAVE_LOCALTIME_R || ! HAVE_TZSET
+#  undef localtime_r
+#  define localtime_r zdump_localtime_r
+static struct tm *
+localtime_r(time_t *tp, struct tm *tmp)
+{
+  struct tm *r = localtime(tp);
+  if (r) {
+    *tmp = *r;
+    r = tmp;
+  }
+  return r;
+}
+# endif
+
+# undef localtime_rz
+# define localtime_rz zdump_localtime_rz
+static struct tm *
+localtime_rz(timezone_t rz, time_t *tp, struct tm *tmp)
+{
+  return localtime_r(tp, tmp);
+}
+
+# ifdef TYPECHECK
+#  undef mktime_z
+#  define mktime_z zdump_mktime_z
+static time_t
+mktime_z(timezone_t tz, struct tm *tmp)
+{
+  return mktime(tmp);
+}
+# endif
+
+# undef tzalloc
+# undef tzfree
+# define tzalloc zdump_tzalloc
+# define tzfree zdump_tzfree
+
+static timezone_t
+tzalloc(char const *val)
+{
+  static char **fakeenv;
+  char **env = fakeenv;
+  char *env0;
+  if (! env) {
+    char **e = environ;
+    int to;
+
+    while (*e++)
+      continue;
+    env = malloc(sumsize(sizeof *environ,
+			 (e - environ) * sizeof *environ));
+    if (! env) {
+      perror(progname);
+      exit(EXIT_FAILURE);
+    }
+    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);
+  }
+  env[0] = strcat(strcpy(env0, "TZ="), val);
+  environ = fakeenv = env;
+  tzset();
+  return env;
+}
+
+static void
+tzfree(timezone_t env)
+{
+  environ = env + 1;
+  free(env[0]);
+}
+#endif /* ! USE_LOCALTIME_RZ */
+
+/* A UTC time zone, and its initializer.  */
+static timezone_t gmtz;
+static void
+gmtzinit(void)
+{
+  if (USE_LOCALTIME_RZ) {
+    static char const utc[] = "UTC0";
+    gmtz = tzalloc(utc);
+    if (!gmtz) {
+      perror(utc);
+      exit(EXIT_FAILURE);
+    }
+  }
+}
+
+/* Convert *TP to UTC, storing the broken-down time into *TMP.
+   Return TMP if successful, NULL otherwise.  This is like gmtime_r(TP, TMP),
+   except typically faster if USE_LOCALTIME_RZ.  */
+static struct tm *
+my_gmtime_r(time_t *tp, struct tm *tmp)
+{
+  return USE_LOCALTIME_RZ ? localtime_rz(gmtz, tp, tmp) : gmtime_r(tp, tmp);
+}
 
 #ifndef TYPECHECK
-#define my_localtime	localtime
+# define my_localtime_rz localtime_rz
 #else /* !defined TYPECHECK */
+
 static struct tm *
-my_localtime(time_t *tp)
+my_localtime_rz(timezone_t tz, time_t *tp, struct tm *tmp)
 {
-	register struct tm *	tmp;
-
-	tmp = localtime(tp);
-	if (tp != NULL && tmp != NULL) {
+	tmp = localtime_rz(tz, tp, tmp);
+	if (tmp) {
 		struct tm	tm;
 		register time_t	t;
 
 		tm = *tmp;
-		t = mktime(&tm);
+		t = mktime_z(tz, &tm);
 		if (t != *tp) {
-			(void) fflush(stdout);
-			(void) fprintf(stderr, "\n%s: ", progname);
-			(void) fprintf(stderr, tformat(), *tp);
-			(void) fprintf(stderr, " ->");
-			(void) fprintf(stderr, " year=%d", tmp->tm_year);
-			(void) fprintf(stderr, " mon=%d", tmp->tm_mon);
-			(void) fprintf(stderr, " mday=%d", tmp->tm_mday);
-			(void) fprintf(stderr, " hour=%d", tmp->tm_hour);
-			(void) fprintf(stderr, " min=%d", tmp->tm_min);
-			(void) fprintf(stderr, " sec=%d", tmp->tm_sec);
-			(void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
-			(void) fprintf(stderr, " -> ");
-			(void) fprintf(stderr, tformat(), t);
-			(void) fprintf(stderr, "\n");
+			fflush(stdout);
+			fprintf(stderr, "\n%s: ", progname);
+			fprintf(stderr, tformat(), *tp);
+			fprintf(stderr, " ->");
+			fprintf(stderr, " year=%d", tmp->tm_year);
+			fprintf(stderr, " mon=%d", tmp->tm_mon);
+			fprintf(stderr, " mday=%d", tmp->tm_mday);
+			fprintf(stderr, " hour=%d", tmp->tm_hour);
+			fprintf(stderr, " min=%d", tmp->tm_min);
+			fprintf(stderr, " sec=%d", tmp->tm_sec);
+			fprintf(stderr, " isdst=%d", tmp->tm_isdst);
+			fprintf(stderr, " -> ");
+			fprintf(stderr, tformat(), t);
+			fprintf(stderr, "\n");
+			errout = true;
 		}
 	}
 	return tmp;
@@ -275,88 +488,124 @@ abbrok(const char *const abbrp, const char *const zone)
 	if (warned)
 		return;
 	cp = abbrp;
-	wp = NULL;
-	while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
+	while (is_alpha(*cp) || is_digit(*cp) || *cp == '-' || *cp == '+')
 		++cp;
-	if (cp - abbrp == 0)
-		wp = _("lacks alphabetic at start");
-	else if (cp - abbrp < 3)
-		wp = _("has fewer than 3 alphabetics");
+	if (cp - abbrp < 3)
+	  wp = _("has fewer than 3 characters");
 	else if (cp - abbrp > 6)
-		wp = _("has more than 6 alphabetics");
-	if (wp == NULL && (*cp == '+' || *cp == '-')) {
-		++cp;
-		if (isascii((unsigned char) *cp) &&
-			isdigit((unsigned char) *cp))
-				if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
-					++cp;
-		if (*cp != '\0')
-			wp = _("differs from POSIX standard");
-	}
-	if (wp == NULL)
-		return;
-	(void) fflush(stdout);
-	(void) fprintf(stderr,
+	  wp = _("has more than 6 characters");
+	else if (*cp)
+	  wp = _("has characters other than ASCII alphanumerics, '-' or '+'");
+	else
+	  return;
+	fflush(stdout);
+	fprintf(stderr,
 		_("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
 		progname, zone, abbrp, wp);
-	warned = TRUE;
+	warned = errout = true;
+}
+
+/* Return a time zone abbreviation.  If the abbreviation needs to be
+   saved, use *BUF (of size *BUFALLOC) to save it, and return the
+   abbreviation in the possibly-reallocated *BUF.  Otherwise, just
+   return the abbreviation.  Get the abbreviation from TMP.
+   Exit on memory allocation failure.  */
+static char const *
+saveabbr(char **buf, size_t *bufalloc, struct tm const *tmp)
+{
+  char const *ab = abbr(tmp);
+  if (HAVE_LOCALTIME_RZ)
+    return ab;
+  else {
+    size_t ablen = strlen(ab);
+    if (*bufalloc <= ablen) {
+      free(*buf);
+
+      /* Make the new buffer at least twice as long as the old,
+	 to avoid O(N**2) behavior on repeated calls.  */
+      *bufalloc = sumsize(*bufalloc, ablen + 1);
+
+      *buf = malloc(*bufalloc);
+      if (! *buf) {
+	perror(progname);
+	exit(EXIT_FAILURE);
+      }
+    }
+    return strcpy(*buf, ab);
+  }
+}
+
+static void
+close_file(FILE *stream)
+{
+  char const *e = (ferror(stream) ? _("I/O error")
+		   : fclose(stream) != 0 ? strerror(errno) : NULL);
+  if (e) {
+    fprintf(stderr, "%s: %s\n", progname, e);
+    exit(EXIT_FAILURE);
+  }
 }
 
 static void
 usage(FILE * const stream, const int status)
 {
-	(void) fprintf(stream,
+	fprintf(stream,
 _("%s: usage: %s [--version] [--help] [-{vV}] [-{ct} [lo,]hi] zonename ...\n"
   "\n"
   "Report bugs to %s.\n"),
 		       progname, progname, REPORT_BUGS_TO);
+	if (status == EXIT_SUCCESS)
+	  close_file(stream);
 	exit(status);
 }
 
 int
 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 int		vflag;
-	register int		Vflag;
+	register bool		vflag;
+	register bool		Vflag;
 	register char *		cutarg;
 	register char *		cuttimes;
 	register time_t		cutlotime;
 	register time_t		cuthitime;
-	register char **	fakeenv;
 	time_t			now;
 	time_t			t;
 	time_t			newt;
 	struct tm		tm;
-	struct tm		newtm;
 	register struct tm *	tmp;
 	register struct tm *	newtmp;
 
 	cutlotime = absolute_min_time;
 	cuthitime = absolute_max_time;
 #if HAVE_GETTEXT
-	(void) setlocale(LC_ALL, "");
+	setlocale(LC_ALL, "");
 #ifdef TZ_DOMAINDIR
-	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
+	bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
 #endif /* defined TEXTDOMAINDIR */
-	(void) textdomain(TZ_DOMAIN);
+	textdomain(TZ_DOMAIN);
 #endif /* HAVE_GETTEXT */
 	progname = argv[0];
 	for (i = 1; i < argc; ++i)
 		if (strcmp(argv[i], "--version") == 0) {
-			(void) printf("zdump %s%s\n", PKGVERSION, TZVERSION);
-			exit(EXIT_SUCCESS);
+			printf("zdump %s%s\n", PKGVERSION, TZVERSION);
+			return EXIT_SUCCESS;
 		} else if (strcmp(argv[i], "--help") == 0) {
 			usage(stdout, EXIT_SUCCESS);
 		}
-	vflag = Vflag = 0;
+	vflag = Vflag = false;
 	cutarg = cuttimes = NULL;
 	for (;;)
 	  switch (getopt(argc, argv, "c:t:vV")) {
 	  case 'c': cutarg = optarg; break;
 	  case 't': cuttimes = optarg; break;
-	  case 'v': vflag = 1; break;
-	  case 'V': Vflag = 1; break;
+	  case 'v': vflag = true; break;
+	  case 'V': Vflag = true; break;
 	  case -1:
 	    if (! (optind == argc - 1 && strcmp(argv[optind], "=") == 0))
 	      goto arg_processing_done;
@@ -383,9 +632,9 @@ main(int argc, char *argv[])
 				cutloyear = lo;
 				cuthiyear = hi;
 			} else {
-(void) fprintf(stderr, _("%s: wild -c argument %s\n"),
+				fprintf(stderr, _("%s: wild -c argument %s\n"),
 					progname, cutarg);
-				exit(EXIT_FAILURE);
+				return EXIT_FAILURE;
 			}
 		}
 		if (cutarg != NULL || cuttimes == NULL) {
@@ -415,81 +664,61 @@ main(int argc, char *argv[])
 					cuthitime = hi;
 				}
 			} else {
-				(void) fprintf(stderr,
+				fprintf(stderr,
 					_("%s: wild -t argument %s\n"),
 					progname, cuttimes);
-				exit(EXIT_FAILURE);
+				return EXIT_FAILURE;
 			}
 		}
 	}
-	(void) time(&now);
+	gmtzinit();
+	now = time(NULL);
 	longest = 0;
-	for (i = optind; i < argc; ++i)
-		if (strlen(argv[i]) > longest)
-			longest = strlen(argv[i]);
-	{
-		register int	from;
-		register int	to;
-
-		for (i = 0; environ[i] != NULL; ++i)
-			continue;
-		fakeenv = malloc((i + 2) * sizeof *fakeenv);
-		if (fakeenv == NULL
-		    || (fakeenv[0] = malloc(longest + 4)) == NULL) {
-					(void) perror(progname);
-					exit(EXIT_FAILURE);
-		}
-		to = 0;
-		(void) strcpy(fakeenv[to++], "TZ=");
-		for (from = 0; environ[from] != NULL; ++from)
-			if (strncmp(environ[from], "TZ=", 3) != 0)
-				fakeenv[to++] = environ[from];
-		fakeenv[to] = NULL;
-		environ = fakeenv;
+	for (i = optind; i < argc; i++) {
+	  size_t arglen = strlen(argv[i]);
+	  if (longest < arglen)
+	    longest = arglen < INT_MAX ? arglen : INT_MAX;
 	}
-	for (i = optind; i < argc; ++i) {
-		static char	buf[MAX_STRING_LENGTH];
 
-		(void) strcpy(&fakeenv[0][3], argv[i]);
+	for (i = optind; i < argc; ++i) {
+		timezone_t tz = tzalloc(argv[i]);
+		char const *ab;
+		if (!tz) {
+		  perror(argv[i]);
+		  return EXIT_FAILURE;
+		}
 		if (! (vflag | Vflag)) {
-			show(argv[i], now, FALSE);
+			show(tz, argv[i], now, false);
+			tzfree(tz);
 			continue;
 		}
-		warned = FALSE;
+		warned = false;
 		t = absolute_min_time;
 		if (!Vflag) {
-			show(argv[i], t, TRUE);
+			show(tz, argv[i], t, true);
 			t += SECSPERDAY;
-			show(argv[i], t, TRUE);
+			show(tz, argv[i], t, true);
 		}
 		if (t < cutlotime)
 			t = cutlotime;
-		tmp = my_localtime(&t);
-		if (tmp != NULL) {
-			tm = *tmp;
-			(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
-		}
-		for ( ; ; ) {
-			newt = (t < absolute_max_time - SECSPERDAY / 2
+		tmp = my_localtime_rz(tz, &t, &tm);
+		if (tmp)
+		  ab = saveabbr(&abbrev, &abbrevsize, &tm);
+		while (t < cuthitime) {
+			newt = ((t < absolute_max_time - SECSPERDAY / 2
+				 && t + SECSPERDAY / 2 < cuthitime)
 				? t + SECSPERDAY / 2
-				: absolute_max_time);
-			if (cuthitime <= newt)
-				break;
-			newtmp = localtime(&newt);
-			if (newtmp != NULL)
-				newtm = *newtmp;
+				: 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), buf) != 0)) {
-					newt = hunt(argv[i], t, newt);
-					newtmp = localtime(&newt);
-					if (newtmp != NULL) {
-						newtm = *newtmp;
-						(void) strncpy(buf,
-							abbr(&newtm),
-							(sizeof buf) - 1);
-					}
+				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;
@@ -498,23 +727,20 @@ main(int argc, char *argv[])
 		if (!Vflag) {
 			t = absolute_max_time;
 			t -= SECSPERDAY;
-			show(argv[i], t, TRUE);
+			show(tz, argv[i], t, true);
 			t += SECSPERDAY;
-			show(argv[i], t, TRUE);
+			show(tz, argv[i], t, true);
 		}
+		tzfree(tz);
 	}
-	if (fflush(stdout) || ferror(stdout)) {
-		(void) fprintf(stderr, "%s: ", progname);
-		(void) perror(_("Error writing to standard output"));
-		exit(EXIT_FAILURE);
-	}
-	exit(EXIT_SUCCESS);
-	/* If exit fails to exit... */
-	return EXIT_FAILURE;
+	close_file(stdout);
+	if (errout && (ferror(stderr) || fclose(stderr) != 0))
+	  return EXIT_FAILURE;
+	return EXIT_SUCCESS;
 }
 
 static time_t
-yeartot(const intmax_t y)
+yeartot(intmax_t y)
 {
 	register intmax_t	myy, seconds, years;
 	register time_t		t;
@@ -557,20 +783,20 @@ yeartot(const intmax_t y)
 }
 
 static time_t
-hunt(char *name, time_t lot, time_t hit)
+hunt(timezone_t tz, char *name, time_t lot, time_t hit)
 {
+	static char *		loab;
+	static size_t		loabsize;
+	char const *		ab;
 	time_t			t;
 	struct tm		lotm;
 	register struct tm *	lotmp;
 	struct tm		tm;
 	register struct tm *	tmp;
-	char			loab[MAX_STRING_LENGTH];
 
-	lotmp = my_localtime(&lot);
-	if (lotmp != NULL) {
-		lotm = *lotmp;
-		(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
-	}
+	lotmp = my_localtime_rz(tz, &lot, &lotm);
+	if (lotmp)
+	  ab = saveabbr(&loab, &loabsize, &lotm);
 	for ( ; ; ) {
 		time_t diff = hit - lot;
 		if (diff < 2)
@@ -581,20 +807,18 @@ hunt(char *name, time_t lot, time_t hit)
 			++t;
 		else if (t >= hit)
 			--t;
-		tmp = my_localtime(&t);
-		if (tmp != NULL)
-			tm = *tmp;
+		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), loab) == 0)) {
+			strcmp(abbr(&tm), ab) == 0)) {
 				lot = t;
 				lotm = tm;
 				lotmp = tmp;
 		} else	hit = t;
 	}
-	show(name, lot, TRUE);
-	show(name, hit, TRUE);
+	show(tz, name, lot, true);
+	show(tz, name, hit, true);
 	return hit;
 }
 
@@ -623,49 +847,87 @@ delta(struct tm * newp, struct tm *oldp)
 	return result;
 }
 
+#ifndef TM_GMTOFF
+/* Return A->tm_yday, adjusted to compare it fairly to B->tm_yday.
+   Assume A and B differ by at most one year.  */
+static int
+adjusted_yday(struct tm const *a, struct tm const *b)
+{
+  int yday = a->tm_yday;
+  if (b->tm_year < a->tm_year)
+    yday += 365 + isleap_sum(b->tm_year, TM_YEAR_BASE);
+  return yday;
+}
+#endif
+
+/* 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.  */
+static long
+gmtoff(struct tm const *a, struct tm const *b)
+{
+#ifdef TM_GMTOFF
+  return a->TM_GMTOFF;
+#else
+  if (! b)
+    return LONG_MIN;
+  else {
+    int ayday = adjusted_yday(a, b);
+    int byday = adjusted_yday(b, a);
+    int days = ayday - byday;
+    long hours = a->tm_hour - b->tm_hour + 24 * days;
+    long minutes = a->tm_min - b->tm_min + 60 * hours;
+    long seconds = a->tm_sec - b->tm_sec + 60 * minutes;
+    return seconds;
+  }
+#endif
+}
+
 static void
-show(char *zone, time_t t, int v)
+show(timezone_t tz, char *zone, time_t t, bool v)
 {
 	register struct tm *	tmp;
+	register struct tm *	gmtmp;
+	struct tm tm, gmtm;
 
-	(void) printf("%-*s  ", (int) longest, zone);
+	printf("%-*s  ", longest, zone);
 	if (v) {
-		tmp = gmtime(&t);
-		if (tmp == NULL) {
-			(void) printf(tformat(), t);
+		gmtmp = my_gmtime_r(&t, &gmtm);
+		if (gmtmp == NULL) {
+			printf(tformat(), t);
 		} else {
-			dumptime(tmp);
-			(void) printf(" UT");
+			dumptime(gmtmp);
+			printf(" UT");
 		}
-		(void) printf(" = ");
+		printf(" = ");
 	}
-	tmp = my_localtime(&t);
+	tmp = my_localtime_rz(tz, &t, &tm);
 	dumptime(tmp);
 	if (tmp != NULL) {
 		if (*abbr(tmp) != '\0')
-			(void) printf(" %s", abbr(tmp));
+			printf(" %s", abbr(tmp));
 		if (v) {
-			(void) printf(" isdst=%d", tmp->tm_isdst);
-#ifdef TM_GMTOFF
-			(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
-#endif /* defined TM_GMTOFF */
+			long off = gmtoff(tmp, gmtmp);
+			printf(" isdst=%d", tmp->tm_isdst);
+			if (off != LONG_MIN)
+			  printf(" gmtoff=%ld", off);
 		}
 	}
-	(void) printf("\n");
+	printf("\n");
 	if (tmp != NULL && *abbr(tmp) != '\0')
 		abbrok(abbr(tmp), zone);
 }
 
-static char *
-abbr(struct tm *tmp)
+static char const *
+abbr(struct tm const *tmp)
 {
-	register char *	result;
-	static char	nada;
-
-	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
-		return &nada;
-	result = tzname[tmp->tm_isdst];
-	return (result == NULL) ? &nada : result;
+#ifdef TM_ZONE
+	return tmp->TM_ZONE;
+#else
+	return (0 <= tmp->tm_isdst && tzname[0 < tmp->tm_isdst]
+		? tzname[0 < tmp->tm_isdst]
+		: "");
+#endif
 }
 
 /*
@@ -712,11 +974,11 @@ dumptime(register const struct tm *timeptr)
 	register int		trail;
 
 	if (timeptr == NULL) {
-		(void) printf("NULL");
+		printf("NULL");
 		return;
 	}
 	/*
-	** The packaged versions of localtime and gmtime never put out-of-range
+	** The packaged localtime_rz and gmtime_r never put out-of-range
 	** values in tm_wday or tm_mon, but since this code might be compiled
 	** with other (perhaps experimental) versions, paranoia is in order.
 	*/
@@ -728,7 +990,7 @@ dumptime(register const struct tm *timeptr)
 		(int) (sizeof mon_name / sizeof mon_name[0]))
 			mn = "???";
 	else		mn = mon_name[timeptr->tm_mon];
-	(void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
+	printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
 		wn, mn,
 		timeptr->tm_mday, timeptr->tm_hour,
 		timeptr->tm_min, timeptr->tm_sec);
@@ -745,6 +1007,6 @@ dumptime(register const struct tm *timeptr)
 		++lead;
 	}
 	if (lead == 0)
-		(void) printf("%d", trail);
-	else	(void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
+		printf("%d", trail);
+	else	printf("%d%d", lead, ((trail < 0) ? -trail : trail));
 }
diff --git a/timezone/zic.c b/timezone/zic.c
index 07d6c30ae2..78ab870941 100644
--- a/timezone/zic.c
+++ b/timezone/zic.c
@@ -23,7 +23,7 @@ typedef int_fast64_t	zic_t;
 #endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
 
 #if HAVE_SYS_STAT_H
-#include "sys/stat.h"
+#include <sys/stat.h>
 #endif
 #ifdef S_IRUSR
 #define MKDIR_UMASK (S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
@@ -31,21 +31,6 @@ typedef int_fast64_t	zic_t;
 #define MKDIR_UMASK 0755
 #endif
 
-/*
-** On some ancient hosts, predicates like `isspace(C)' are defined
-** only if isascii(C) || C == EOF. Modern hosts obey the C Standard,
-** which says they are defined only if C == ((unsigned char) C) || C == EOF.
-** Neither the C Standard nor Posix require that `isascii' exist.
-** For portability, we check both ancient and modern requirements.
-** If isascii is not defined, the isascii check succeeds trivially.
-*/
-#include "ctype.h"
-#ifndef isascii
-#define isascii(x) 1
-#endif
-
-#define end(cp)	(strchr((cp), '\0'))
-
 struct rule {
 	const char *	r_filename;
 	int		r_linenum;
@@ -54,8 +39,8 @@ struct rule {
 	zic_t		r_loyear;	/* for example, 1986 */
 	zic_t		r_hiyear;	/* for example, 1986 */
 	const char *	r_yrtype;
-	int		r_lowasnum;
-	int		r_hiwasnum;
+	bool		r_lowasnum;
+	bool		r_hiwasnum;
 
 	int		r_month;	/* 0..11 */
 
@@ -64,10 +49,10 @@ struct rule {
 	int		r_wday;
 
 	zic_t		r_tod;		/* time from midnight */
-	int		r_todisstd;	/* above is standard time if TRUE */
-					/* or wall clock time if FALSE */
-	int		r_todisgmt;	/* above is GMT if TRUE */
-					/* or local time if FALSE */
+	bool		r_todisstd;	/* above is standard time if 1 */
+					/* or wall clock time if 0 */
+	bool		r_todisgmt;	/* above is GMT if 1 */
+					/* or local time if 0 */
 	zic_t		r_stdoff;	/* offset from standard time */
 	const char *	r_abbrvar;	/* variable part of abbreviation */
 
@@ -91,6 +76,7 @@ struct zone {
 	zic_t		z_gmtoff;
 	const char *	z_rule;
 	const char *	z_format;
+	char		z_format_specifier;
 
 	zic_t		z_stdoff;
 
@@ -115,25 +101,25 @@ extern int	optind;
 #endif
 
 static void	addtt(zic_t starttime, int type);
-static int	addtype(zic_t gmtoff, const char * abbr, int isdst,
-				int ttisstd, int ttisgmt);
-static void	leapadd(zic_t t, int positive, int rolling, int count);
+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 char **	getfields(char * buf);
-static zic_t	gethms(const char * string, const char * errstrng,
-		       int signable);
+static zic_t	gethms(const char * string, const char * errstring,
+		       bool);
 static void	infile(const char * filename);
 static void	inleap(char ** fields, int nfields);
 static void	inlink(char ** fields, int nfields);
 static void	inrule(char ** fields, int nfields);
-static int	inzcont(char ** fields, int nfields);
-static int	inzone(char ** fields, int nfields);
-static int	inzsub(char ** fields, int nfields, int iscont);
+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 int	lowerit(int c);
-static int	mkdirs(char * filename);
+static bool	is_alpha(char a);
+static char	lowerit(char);
+static bool	mkdirs(char *);
 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);
@@ -143,21 +129,25 @@ static void	rulesub(struct rule * rp,
 			const char * typep, const char * monthp,
 			const char * dayp, const char * timep);
 static zic_t	tadd(zic_t t1, zic_t t2);
-static int	yearistype(int year, const char * type);
+static bool	yearistype(int year, const char * type);
+
+/* Bound on length of what %z can expand to.  */
+enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };
 
 static int		charcnt;
-static int		errors;
+static bool		errors;
+static bool		warnings;
 static const char *	filename;
 static int		leapcnt;
-static int		leapseen;
+static bool		leapseen;
 static zic_t		leapminyear;
 static zic_t		leapmaxyear;
 static int		linenum;
-static int		max_abbrvar_len;
+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 int		noise;
+static bool		noise;
 static const char *	rfilename;
 static int		rlinenum;
 static const char *	progname;
@@ -333,8 +323,8 @@ static struct lookup const	end_years[] = {
 };
 
 static struct lookup const	leap_types[] = {
-	{ "Rolling",	TRUE },
-	{ "Stationary",	FALSE },
+	{ "Rolling",	true },
+	{ "Stationary",	false },
 	{ NULL,		0 }
 };
 
@@ -354,8 +344,8 @@ static struct attype {
 static zic_t		gmtoffs[TZ_MAX_TYPES];
 static char		isdsts[TZ_MAX_TYPES];
 static unsigned char	abbrinds[TZ_MAX_TYPES];
-static char		ttisstds[TZ_MAX_TYPES];
-static char		ttisgmts[TZ_MAX_TYPES];
+static bool		ttisstds[TZ_MAX_TYPES];
+static bool		ttisgmts[TZ_MAX_TYPES];
 static char		chars[TZ_MAX_CHARS];
 static zic_t		trans[TZ_MAX_LEAPS];
 static zic_t		corr[TZ_MAX_LEAPS];
@@ -376,22 +366,44 @@ static ATTRIBUTE_PURE size_t
 size_product(size_t nitems, size_t itemsize)
 {
 	if (SIZE_MAX / itemsize < nitems)
-		memory_exhausted("size overflow");
+		memory_exhausted(_("size overflow"));
 	return nitems * itemsize;
 }
 
+#if !HAVE_STRDUP
+static char *
+strdup(char const *str)
+{
+  char *result = malloc(strlen(str) + 1);
+  return result ? strcpy(result, str) : result;
+}
+#endif
+
 static ATTRIBUTE_PURE void *
-memcheck(void *const ptr)
+memcheck(void *ptr)
 {
 	if (ptr == NULL)
 		memory_exhausted(strerror(errno));
 	return ptr;
 }
 
-#define emalloc(size)		memcheck(malloc(size))
-#define erealloc(ptr, size)	memcheck(realloc(ptr, size))
-#define ecpyalloc(ptr)		memcheck(icpyalloc(ptr))
-#define ecatalloc(oldp, newp)	memcheck(icatalloc((oldp), (newp)))
+static void *
+emalloc(size_t size)
+{
+  return memcheck(malloc(size));
+}
+
+static void *
+erealloc(void *ptr, size_t size)
+{
+  return memcheck(realloc(ptr, size));
+}
+
+static char *
+ecpyalloc (char const *str)
+{
+  return memcheck(strdup(str));
+}
 
 static void *
 growalloc(void *ptr, size_t itemsize, int nitems, int *nitems_alloc)
@@ -401,7 +413,7 @@ growalloc(void *ptr, size_t itemsize, int nitems, int *nitems_alloc)
 	else {
 		int amax = INT_MAX < SIZE_MAX ? INT_MAX : SIZE_MAX;
 		if ((amax - 1) / 3 * 2 < *nitems_alloc)
-			memory_exhausted("int overflow");
+			memory_exhausted(_("int overflow"));
 		*nitems_alloc = *nitems_alloc + (*nitems_alloc >> 1) + 1;
 		return erealloc(ptr, size_product(*nitems_alloc, itemsize));
 	}
@@ -435,13 +447,13 @@ verror(const char *const string, va_list args)
 	**	zic ... 2>&1 | error -t "*" -v
 	** on BSD systems.
 	*/
-	fprintf(stderr, _("\"%s\", line %d: "), filename, linenum);
+	if (filename)
+	  fprintf(stderr, _("\"%s\", line %d: "), filename, linenum);
 	vfprintf(stderr, string, args);
 	if (rfilename != NULL)
-		(void) fprintf(stderr, _(" (rule from \"%s\", line %d)"),
+		fprintf(stderr, _(" (rule from \"%s\", line %d)"),
 			rfilename, rlinenum);
-	(void) fprintf(stderr, "\n");
-	++errors;
+	fprintf(stderr, "\n");
 }
 
 static void ATTRIBUTE_FORMAT((printf, 1, 2))
@@ -451,6 +463,7 @@ error(const char *const string, ...)
 	va_start(args, string);
 	verror(string, args);
 	va_end(args);
+	errors = true;
 }
 
 static void ATTRIBUTE_FORMAT((printf, 1, 2))
@@ -461,19 +474,35 @@ warning(const char *const string, ...)
 	va_start(args, string);
 	verror(string, args);
 	va_end(args);
-	--errors;
+	warnings = true;
+}
+
+static void
+close_file(FILE *stream, 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);
+    exit(EXIT_FAILURE);
+  }
 }
 
 static _Noreturn void
 usage(FILE *stream, int status)
 {
-	(void) fprintf(stream, _("%s: usage is %s \
-[ --version ] [ --help ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
-\t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n\
-\n\
-Report bugs to %s.\n"),
-		       progname, progname, REPORT_BUGS_TO);
-	exit(status);
+  fprintf(stream,
+	  _("%s: usage is %s [ --version ] [ --help ] [ -v ] \\\n"
+	    "\t[ -l localtime ] [ -p posixrules ] [ -d directory ] \\\n"
+	    "\t[ -L leapseconds ] [ filename ... ]\n\n"
+	    "Report bugs to %s.\n"),
+	  progname, progname, REPORT_BUGS_TO);
+  if (status == EXIT_SUCCESS)
+    close_file(stream, NULL);
+  exit(status);
 }
 
 static const char *	psxrules;
@@ -490,25 +519,26 @@ main(int argc, char **argv)
 	register int	c;
 
 #ifdef S_IWGRP
-	(void) umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
+	umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
 #endif
 #if HAVE_GETTEXT
-	(void) setlocale(LC_ALL, "");
+	setlocale(LC_ALL, "");
 #ifdef TZ_DOMAINDIR
-	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
+	bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
 #endif /* defined TEXTDOMAINDIR */
-	(void) textdomain(TZ_DOMAIN);
+	textdomain(TZ_DOMAIN);
 #endif /* HAVE_GETTEXT */
 	progname = argv[0];
 	if (TYPE_BIT(zic_t) < 64) {
-		(void) fprintf(stderr, "%s: %s\n", progname,
+		fprintf(stderr, "%s: %s\n", progname,
 			_("wild compilation-time specification of zic_t"));
-		exit(EXIT_FAILURE);
+		return EXIT_FAILURE;
 	}
 	for (i = 1; i < argc; ++i)
 		if (strcmp(argv[i], "--version") == 0) {
-			(void) printf("zic %s%s\n", PKGVERSION, TZVERSION);
-			exit(EXIT_SUCCESS);
+			printf("zic %s%s\n", PKGVERSION, TZVERSION);
+			close_file(stdout, NULL);
+			return EXIT_SUCCESS;
 		} else if (strcmp(argv[i], "--help") == 0) {
 			usage(stdout, EXIT_SUCCESS);
 		}
@@ -520,57 +550,57 @@ main(int argc, char **argv)
 				if (directory == NULL)
 					directory = optarg;
 				else {
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: More than one -d option specified\n"),
 						progname);
-					exit(EXIT_FAILURE);
+					return EXIT_FAILURE;
 				}
 				break;
 			case 'l':
 				if (lcltime == NULL)
 					lcltime = optarg;
 				else {
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: More than one -l option specified\n"),
 						progname);
-					exit(EXIT_FAILURE);
+					return EXIT_FAILURE;
 				}
 				break;
 			case 'p':
 				if (psxrules == NULL)
 					psxrules = optarg;
 				else {
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: More than one -p option specified\n"),
 						progname);
-					exit(EXIT_FAILURE);
+					return EXIT_FAILURE;
 				}
 				break;
 			case 'y':
 				if (yitcommand == NULL)
 					yitcommand = optarg;
 				else {
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: More than one -y option specified\n"),
 						progname);
-					exit(EXIT_FAILURE);
+					return EXIT_FAILURE;
 				}
 				break;
 			case 'L':
 				if (leapsec == NULL)
 					leapsec = optarg;
 				else {
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: More than one -L option specified\n"),
 						progname);
-					exit(EXIT_FAILURE);
+					return EXIT_FAILURE;
 				}
 				break;
 			case 'v':
-				noise = TRUE;
+				noise = true;
 				break;
 			case 's':
-				(void) printf("%s: -s ignored\n", progname);
+				warning(_("-s ignored"));
 				break;
 		}
 	if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
@@ -588,7 +618,7 @@ _("%s: More than one -L option specified\n"),
 	for (i = optind; i < argc; ++i)
 		infile(argv[i]);
 	if (errors)
-		exit(EXIT_FAILURE);
+		return EXIT_FAILURE;
 	associate();
 	for (i = 0; i < nzones; i = j) {
 		/*
@@ -611,53 +641,137 @@ _("%s: More than one -L option specified\n"),
 						warning(_("link to link"));
 	}
 	if (lcltime != NULL) {
-		eat("command line", 1);
+		eat(_("command line"), 1);
 		dolink(lcltime, TZDEFAULT);
 	}
 	if (psxrules != NULL) {
-		eat("command line", 1);
+		eat(_("command line"), 1);
 		dolink(psxrules, TZDEFRULES);
 	}
-	return (errors == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+	if (warnings && (ferror(stderr) || fclose(stderr) != 0))
+	  return EXIT_FAILURE;
+	return errors ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+static bool
+componentcheck(char const *name, char const *component,
+	       char const *component_end)
+{
+	enum { component_len_max = 14 };
+	size_t component_len = component_end - component;
+	if (component_len == 0) {
+	  if (!*name)
+	    error (_("empty file name"));
+	  else
+	    error (_(component == name
+		     ? "file name '%s' begins with '/'"
+		     : *component_end
+		     ? "file name '%s' contains '//'"
+		     : "file name '%s' ends with '/'"),
+		   name);
+	  return false;
+	}
+	if (0 < component_len && component_len <= 2
+	    && component[0] == '.' && component_end[-1] == '.') {
+	  error(_("file name '%s' contains '%.*s' component"),
+		name, (int) component_len, component);
+	  return false;
+	}
+	if (noise) {
+	  if (0 < component_len && component[0] == '-')
+	    warning(_("file name '%s' component contains leading '-'"),
+		    name);
+	  if (component_len_max < component_len)
+	    warning(_("file name '%s' contains overlength component"
+		      " '%.*s...'"),
+		    name, component_len_max, component);
+	}
+	return true;
+}
+
+static bool
+namecheck(const char *name)
+{
+	register char const *cp;
+
+	/* Benign characters in a portable file name.  */
+	static char const benign[] =
+	  "-/_"
+	  "abcdefghijklmnopqrstuvwxyz"
+	  "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+	/* Non-control chars in the POSIX portable character set,
+	   excluding the benign characters.  */
+	static char const printable_and_not_benign[] =
+	  " !\"#$%&'()*+,.0123456789:;<=>?@[\\]^`{|}~";
+
+	register char const *component = name;
+	for (cp = name; *cp; cp++) {
+		unsigned char c = *cp;
+		if (noise && !strchr(benign, c)) {
+			warning((strchr(printable_and_not_benign, c)
+				 ? _("file name '%s' contains byte '%c'")
+				 : _("file name '%s' contains byte '\\%o'")),
+				name, c);
+		}
+		if (c == '/') {
+			if (!componentcheck(name, component, cp))
+			  return false;
+			component = cp + 1;
+		}
+	}
+	return componentcheck(name, component, cp);
+}
+
+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);
+  }
 }
 
 static void
-dolink(const char *const fromfield, const char *const tofield)
+dolink(char const *fromfield, char const *tofield)
 {
 	register char *	fromname;
 	register char *	toname;
+	register int fromisdir;
 
-	if (fromfield[0] == '/')
-		fromname = ecpyalloc(fromfield);
-	else {
-		fromname = ecpyalloc(directory);
-		fromname = ecatalloc(fromname, "/");
-		fromname = ecatalloc(fromname, fromfield);
-	}
-	if (tofield[0] == '/')
-		toname = ecpyalloc(tofield);
-	else {
-		toname = ecpyalloc(directory);
-		toname = ecatalloc(toname, "/");
-		toname = ecatalloc(toname, tofield);
-	}
+	fromname = relname(directory, fromfield);
+	toname = relname(directory, tofield);
 	/*
 	** We get to be careful here since
 	** there's a fair chance of root running us.
 	*/
-	if (!itsdir(toname))
-		(void) remove(toname);
-	if (link(fromname, toname) != 0
-	    && access(fromname, F_OK) == 0 && !itsdir(fromname)) {
+	fromisdir = itsdir(fromname);
+	if (fromisdir) {
+		char const *e = strerror(fromisdir < 0 ? errno : EPERM);
+		fprintf(stderr, _("%s: link from %s failed: %s"),
+			progname, fromname, e);
+		exit(EXIT_FAILURE);
+	}
+	if (itsdir(toname) <= 0)
+		remove(toname);
+	if (link(fromname, toname) != 0) {
 		int	result;
 
-		if (mkdirs(toname) != 0)
+		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
@@ -666,13 +780,13 @@ dolink(const char *const fromfield, const char *const tofield)
 				       && ! strncmp (fromfield, tofield,
 						     ++s - fromfield));
 
-				for (s = tofield + (t - fromfield);
-				     (s = strchr(s, '/'));
-				     s++)
-					symlinkcontents =
-						ecatalloc(symlinkcontents,
-						"../");
-				symlinkcontents = ecatalloc(symlinkcontents, t);
+				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"));
@@ -684,7 +798,7 @@ warning(_("hard link failed, symbolic link used"));
 			fp = fopen(fromname, "rb");
 			if (!fp) {
 				const char *e = strerror(errno);
-				(void) fprintf(stderr,
+				fprintf(stderr,
 					       _("%s: Can't read %s: %s\n"),
 					       progname, fromname, e);
 				exit(EXIT_FAILURE);
@@ -692,25 +806,15 @@ warning(_("hard link failed, symbolic link used"));
 			tp = fopen(toname, "wb");
 			if (!tp) {
 				const char *e = strerror(errno);
-				(void) fprintf(stderr,
+				fprintf(stderr,
 					       _("%s: Can't create %s: %s\n"),
 					       progname, toname, e);
 				exit(EXIT_FAILURE);
 			}
 			while ((c = getc(fp)) != EOF)
 				putc(c, tp);
-			if (ferror(fp) || fclose(fp)) {
-				(void) fprintf(stderr,
-					       _("%s: Error reading %s\n"),
-					       progname, fromname);
-				exit(EXIT_FAILURE);
-			}
-			if (ferror(tp) || fclose(tp)) {
-				(void) fprintf(stderr,
-					       _("%s: Error writing %s\n"),
-					       progname, toname);
-				exit(EXIT_FAILURE);
-			}
+			close_file(fp, fromname);
+			close_file(tp, toname);
 			warning(_("link failed, copy used"));
 		}
 	}
@@ -720,8 +824,8 @@ warning(_("hard link failed, symbolic link used"));
 
 #define TIME_T_BITS_IN_FILE	64
 
-static const zic_t min_time = (zic_t) -1 << (TIME_T_BITS_IN_FILE - 1);
-static const zic_t max_time = -1 - ((zic_t) -1 << (TIME_T_BITS_IN_FILE - 1));
+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
@@ -753,17 +857,24 @@ static const zic_t max_time = -1 - ((zic_t) -1 << (TIME_T_BITS_IN_FILE - 1));
 
 static const zic_t big_bang_time = BIG_BANG;
 
+/* Return 1 if NAME is a directory, 0 if it's something else, -1 if trouble.  */
 static int
-itsdir(const char *const name)
+itsdir(char const *name)
 {
-	register char *	myname;
-	register int	accres;
-
-	myname = ecpyalloc(name);
-	myname = ecatalloc(myname, "/.");
-	accres = access(myname, F_OK);
-	free(myname);
-	return accres == 0;
+	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);
+		free(nameslashdot);
+		return res == 0;
+	}
+#endif
 }
 
 /*
@@ -790,7 +901,7 @@ associate(void)
 	register int		i, j;
 
 	if (nrules != 0) {
-		(void) qsort(rules, nrules, sizeof *rules, rcomp);
+		qsort(rules, nrules, sizeof *rules, rcomp);
 		for (i = 0; i < nrules - 1; ++i) {
 			if (strcmp(rules[i].r_name,
 				rules[i + 1].r_name) != 0)
@@ -843,12 +954,12 @@ associate(void)
 			*/
 			eat(zp->z_filename, zp->z_linenum);
 			zp->z_stdoff = gethms(zp->z_rule, _("unruly zone"),
-				TRUE);
+				true);
 			/*
 			** Note, though, that if there's no rule,
 			** a '%s' in the format is a bad thing.
 			*/
-			if (strchr(zp->z_format, '%') != 0)
+			if (zp->z_format_specifier == 's')
 				error("%s", _("%s in ruleless zone"));
 		}
 	}
@@ -864,7 +975,7 @@ infile(const char *name)
 	register char *			cp;
 	register const struct lookup *	lp;
 	register int			nfields;
-	register int			wantcont;
+	register bool			wantcont;
 	register int			num;
 	char				buf[BUFSIZ];
 
@@ -874,11 +985,11 @@ infile(const char *name)
 	} else if ((fp = fopen(name, "r")) == NULL) {
 		const char *e = strerror(errno);
 
-		(void) fprintf(stderr, _("%s: Can't open %s: %s\n"),
+		fprintf(stderr, _("%s: Can't open %s: %s\n"),
 			progname, name, e);
 		exit(EXIT_FAILURE);
 	}
-	wantcont = FALSE;
+	wantcont = false;
 	for (num = 1; ; ++num) {
 		eat(name, num);
 		if (fgets(buf, sizeof buf, fp) != buf)
@@ -909,25 +1020,25 @@ infile(const char *name)
 			else switch ((int) (lp->l_value)) {
 				case LC_RULE:
 					inrule(fields, nfields);
-					wantcont = FALSE;
+					wantcont = false;
 					break;
 				case LC_ZONE:
 					wantcont = inzone(fields, nfields);
 					break;
 				case LC_LINK:
 					inlink(fields, nfields);
-					wantcont = FALSE;
+					wantcont = false;
 					break;
 				case LC_LEAP:
 					if (name != leapsec)
-						(void) fprintf(stderr,
-_("%s: Leap line in non leap seconds file %s\n"),
-							progname, name);
+					  warning(_("%s: Leap line in non leap"
+						    " seconds file %s"),
+						  progname, name);
 					else	inleap(fields, nfields);
-					wantcont = FALSE;
+					wantcont = false;
 					break;
 				default:	/* "cannot happen" */
-					(void) fprintf(stderr,
+					fprintf(stderr,
 _("%s: panic: Invalid l_value %d\n"),
 						progname, lp->l_value);
 					exit(EXIT_FAILURE);
@@ -935,18 +1046,7 @@ _("%s: panic: Invalid l_value %d\n"),
 		}
 		free(fields);
 	}
-	if (ferror(fp)) {
-		(void) fprintf(stderr, _("%s: Error reading %s\n"),
-			progname, filename);
-		exit(EXIT_FAILURE);
-	}
-	if (fp != stdin && fclose(fp)) {
-		const char *e = strerror(errno);
-
-		(void) fprintf(stderr, _("%s: Error closing %s: %s\n"),
-			progname, filename, e);
-		exit(EXIT_FAILURE);
-	}
+	close_file(fp, filename);
 	if (wantcont)
 		error(_("expected continuation line not found"));
 }
@@ -960,10 +1060,11 @@ _("%s: panic: Invalid l_value %d\n"),
 */
 
 static zic_t
-gethms(const char *string, const char *const errstring, const int signable)
+gethms(char const *string, char const *errstring, bool signable)
 {
 	zic_t	hh;
 	int	mm, ss, sign;
+	char xs;
 
 	if (string == NULL || *string == '\0')
 		return 0;
@@ -973,12 +1074,12 @@ gethms(const char *string, const char *const errstring, const int signable)
 		sign = -1;
 		++string;
 	} else	sign = 1;
-	if (sscanf(string, scheck(string, "%"SCNdZIC), &hh) == 1)
+	if (sscanf(string, "%"SCNdZIC"%c", &hh, &xs) == 1)
 		mm = ss = 0;
-	else if (sscanf(string, scheck(string, "%"SCNdZIC":%d"), &hh, &mm) == 2)
+	else if (sscanf(string, "%"SCNdZIC":%d%c", &hh, &mm, &xs) == 2)
 		ss = 0;
-	else if (sscanf(string, scheck(string, "%"SCNdZIC":%d:%d"),
-		&hh, &mm, &ss) != 3) {
+	else if (sscanf(string, "%"SCNdZIC":%d:%d%c", &hh, &mm, &ss, &xs)
+		 != 3) {
 			error("%s", errstring);
 			return 0;
 	}
@@ -1000,7 +1101,7 @@ warning(_("values over 24 hours not handled by pre-2007 versions of zic"));
 }
 
 static void
-inrule(register char **const fields, const int nfields)
+inrule(char **fields, int nfields)
 {
 	static struct rule	r;
 
@@ -1014,7 +1115,7 @@ inrule(register char **const fields, const int nfields)
 	}
 	r.r_filename = filename;
 	r.r_linenum = linenum;
-	r.r_stdoff = gethms(fields[RF_STDOFF], _("invalid saved time"), TRUE);
+	r.r_stdoff = gethms(fields[RF_STDOFF], _("invalid saved time"), true);
 	rulesub(&r, fields[RF_LOYEAR], fields[RF_HIYEAR], fields[RF_COMMAND],
 		fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
 	r.r_name = ecpyalloc(fields[RF_NAME]);
@@ -1025,26 +1126,26 @@ inrule(register char **const fields, const int nfields)
 	rules[nrules++] = r;
 }
 
-static int
-inzone(register char **const fields, const int nfields)
+static bool
+inzone(char **fields, int nfields)
 {
 	register int	i;
 
 	if (nfields < ZONE_MINFIELDS || nfields > ZONE_MAXFIELDS) {
 		error(_("wrong number of fields on Zone line"));
-		return FALSE;
+		return false;
 	}
 	if (strcmp(fields[ZF_NAME], TZDEFAULT) == 0 && lcltime != NULL) {
 		error(
 _("\"Zone %s\" line and -l option are mutually exclusive"),
 			TZDEFAULT);
-		return FALSE;
+		return false;
 	}
 	if (strcmp(fields[ZF_NAME], TZDEFRULES) == 0 && psxrules != NULL) {
 		error(
 _("\"Zone %s\" line and -p option are mutually exclusive"),
 			TZDEFRULES);
-		return FALSE;
+		return false;
 	}
 	for (i = 0; i < nzones; ++i)
 		if (zones[i].z_name != NULL &&
@@ -1054,30 +1155,31 @@ _("duplicate zone name %s (file \"%s\", line %d)"),
 					fields[ZF_NAME],
 					zones[i].z_filename,
 					zones[i].z_linenum);
-				return FALSE;
+				return false;
 		}
-	return inzsub(fields, nfields, FALSE);
+	return inzsub(fields, nfields, false);
 }
 
-static int
-inzcont(register char **const fields, const int nfields)
+static bool
+inzcont(char **fields, int nfields)
 {
 	if (nfields < ZONEC_MINFIELDS || nfields > ZONEC_MAXFIELDS) {
 		error(_("wrong number of fields on Zone continuation line"));
-		return FALSE;
+		return false;
 	}
-	return inzsub(fields, nfields, TRUE);
+	return inzsub(fields, nfields, true);
 }
 
-static int
-inzsub(register char **const fields, const int nfields, const int iscont)
+static bool
+inzsub(char **fields, int nfields, bool iscont)
 {
 	register char *		cp;
+	char *			cp1;
 	static struct zone	z;
 	register int		i_gmtoff, i_rule, i_format;
 	register int		i_untilyear, i_untilmonth;
 	register int		i_untilday, i_untiltime;
-	register int		hasuntil;
+	register bool		hasuntil;
 
 	if (iscont) {
 		i_gmtoff = ZFC_GMTOFF;
@@ -1088,7 +1190,9 @@ inzsub(register char **const fields, const int nfields, const int iscont)
 		i_untilday = ZFC_TILDAY;
 		i_untiltime = ZFC_TILTIME;
 		z.z_name = NULL;
-	} else {
+	} else if (!namecheck(fields[ZF_NAME]))
+		return false;
+	else {
 		i_gmtoff = ZF_GMTOFF;
 		i_rule = ZF_RULE;
 		i_format = ZF_FORMAT;
@@ -1100,15 +1204,23 @@ inzsub(register char **const fields, const int nfields, const int iscont)
 	}
 	z.z_filename = filename;
 	z.z_linenum = linenum;
-	z.z_gmtoff = gethms(fields[i_gmtoff], _("invalid UT offset"), TRUE);
+	z.z_gmtoff = gethms(fields[i_gmtoff], _("invalid UT offset"), true);
 	if ((cp = strchr(fields[i_format], '%')) != 0) {
-		if (*++cp != 's' || strchr(cp, '%') != 0) {
+		if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
+		    || strchr(fields[i_format], '/')) {
 			error(_("invalid abbreviation format"));
-			return FALSE;
+			return false;
 		}
 	}
 	z.z_rule = ecpyalloc(fields[i_rule]);
-	z.z_format = ecpyalloc(fields[i_format]);
+	z.z_format = cp1 = ecpyalloc(fields[i_format]);
+	z.z_format_specifier = cp ? *cp : '\0';
+	if (z.z_format_specifier == 'z') {
+	  if (noise)
+	    warning(_("format '%s' not handled by pre-2015 versions of zic"),
+		    z.z_format);
+	  cp1[cp - fields[i_format]] = 's';
+	}
 	if (max_format_len < strlen(z.z_format))
 		max_format_len = strlen(z.z_format);
 	hasuntil = nfields > i_untilyear;
@@ -1134,7 +1246,7 @@ inzsub(register char **const fields, const int nfields, const int iscont)
 				error(_(
 "Zone continuation line end time is not after end time of previous line"
 					));
-				return FALSE;
+				return false;
 		}
 	}
 	zones = growalloc(zones, sizeof *zones, nzones, &nzones_alloc);
@@ -1147,7 +1259,7 @@ inzsub(register char **const fields, const int nfields, const int iscont)
 }
 
 static void
-inleap(register char ** const fields, const int nfields)
+inleap(char **fields, int nfields)
 {
 	register const char *		cp;
 	register const struct lookup *	lp;
@@ -1156,6 +1268,7 @@ inleap(register char ** const fields, const int nfields)
 	int				month, day;
 	zic_t				dayoff, tod;
 	zic_t				t;
+	char xs;
 
 	if (nfields != LEAP_FIELDS) {
 		error(_("wrong number of fields on Leap line"));
@@ -1163,7 +1276,7 @@ inleap(register char ** const fields, const int nfields)
 	}
 	dayoff = 0;
 	cp = fields[LP_YEAR];
-	if (sscanf(cp, scheck(cp, "%"SCNdZIC), &year) != 1) {
+	if (sscanf(cp, "%"SCNdZIC"%c", &year, &xs) != 1) {
 		/*
 		** Leapin' Lizards!
 		*/
@@ -1174,7 +1287,7 @@ inleap(register char ** const fields, const int nfields)
 		leapmaxyear = year;
 	if (!leapseen || leapminyear > year)
 		leapminyear = year;
-	leapseen = TRUE;
+	leapseen = true;
 	j = EPOCH_YEAR;
 	while (j != year) {
 		if (year > j) {
@@ -1198,7 +1311,7 @@ inleap(register char ** const fields, const int nfields)
 		++j;
 	}
 	cp = fields[LP_DAY];
-	if (sscanf(cp, scheck(cp, "%d"), &day) != 1 ||
+	if (sscanf(cp, "%d%c", &day, &xs) != 1 ||
 		day <= 0 || day > len_months[isleap(year)][month]) {
 			error(_("invalid day of month"));
 			return;
@@ -1213,23 +1326,23 @@ inleap(register char ** const fields, const int nfields)
 		return;
 	}
 	t = dayoff * SECSPERDAY;
-	tod = gethms(fields[LP_TIME], _("invalid time of day"), FALSE);
+	tod = gethms(fields[LP_TIME], _("invalid time of day"), false);
 	cp = fields[LP_CORR];
 	{
-		register int	positive;
+		register bool	positive;
 		int		count;
 
 		if (strcmp(cp, "") == 0) { /* infile() turns "-" into "" */
-			positive = FALSE;
+			positive = false;
 			count = 1;
 		} else if (strcmp(cp, "--") == 0) {
-			positive = FALSE;
+			positive = false;
 			count = 2;
 		} else if (strcmp(cp, "+") == 0) {
-			positive = TRUE;
+			positive = true;
 			count = 1;
 		} else if (strcmp(cp, "++") == 0) {
-			positive = TRUE;
+			positive = true;
 			count = 2;
 		} else {
 			error(_("illegal CORRECTION field on Leap line"));
@@ -1251,7 +1364,7 @@ inleap(register char ** const fields, const int nfields)
 }
 
 static void
-inlink(register char **const fields, const int nfields)
+inlink(char **fields, int nfields)
 {
 	struct link	l;
 
@@ -1263,10 +1376,8 @@ inlink(register char **const fields, const int nfields)
 		error(_("blank FROM field on Link line"));
 		return;
 	}
-	if (*fields[LF_TO] == '\0') {
-		error(_("blank TO field on Link line"));
-		return;
-	}
+	if (! namecheck(fields[LF_TO]))
+	  return;
 	l.l_filename = filename;
 	l.l_linenum = linenum;
 	l.l_from = ecpyalloc(fields[LF_FROM]);
@@ -1276,50 +1387,47 @@ inlink(register char **const fields, const int nfields)
 }
 
 static void
-rulesub(register struct rule *const rp,
-	const char *const loyearp,
-	const char *const hiyearp,
-	const char *const typep,
-	const char *const monthp,
-	const char *const dayp,
-	const char *const timep)
+rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
+	const char *typep, const char *monthp, const char *dayp,
+	const char *timep)
 {
 	register const struct lookup *	lp;
 	register const char *		cp;
 	register char *			dp;
 	register char *			ep;
+	char xs;
 
 	if ((lp = byword(monthp, mon_names)) == NULL) {
 		error(_("invalid month name"));
 		return;
 	}
 	rp->r_month = lp->l_value;
-	rp->r_todisstd = FALSE;
-	rp->r_todisgmt = FALSE;
+	rp->r_todisstd = false;
+	rp->r_todisgmt = false;
 	dp = ecpyalloc(timep);
 	if (*dp != '\0') {
 		ep = dp + strlen(dp) - 1;
 		switch (lowerit(*ep)) {
 			case 's':	/* Standard */
-				rp->r_todisstd = TRUE;
-				rp->r_todisgmt = FALSE;
+				rp->r_todisstd = true;
+				rp->r_todisgmt = false;
 				*ep = '\0';
 				break;
 			case 'w':	/* Wall */
-				rp->r_todisstd = FALSE;
-				rp->r_todisgmt = FALSE;
+				rp->r_todisstd = false;
+				rp->r_todisgmt = false;
 				*ep = '\0';
 				break;
 			case 'g':	/* Greenwich */
 			case 'u':	/* Universal */
 			case 'z':	/* Zulu */
-				rp->r_todisstd = TRUE;
-				rp->r_todisgmt = TRUE;
+				rp->r_todisstd = true;
+				rp->r_todisgmt = true;
 				*ep = '\0';
 				break;
 		}
 	}
-	rp->r_tod = gethms(dp, _("invalid time of day"), FALSE);
+	rp->r_tod = gethms(dp, _("invalid time of day"), false);
 	free(dp);
 	/*
 	** Year work.
@@ -1335,11 +1443,11 @@ rulesub(register struct rule *const rp,
 			rp->r_loyear = ZIC_MAX;
 			break;
 		default:	/* "cannot happen" */
-			(void) fprintf(stderr,
+			fprintf(stderr,
 				_("%s: panic: Invalid l_value %d\n"),
 				progname, lp->l_value);
 			exit(EXIT_FAILURE);
-	} else if (sscanf(cp, scheck(cp, "%"SCNdZIC), &rp->r_loyear) != 1) {
+	} else if (sscanf(cp, "%"SCNdZIC"%c", &rp->r_loyear, &xs) != 1) {
 		error(_("invalid starting year"));
 		return;
 	}
@@ -1357,11 +1465,11 @@ rulesub(register struct rule *const rp,
 			rp->r_hiyear = rp->r_loyear;
 			break;
 		default:	/* "cannot happen" */
-			(void) fprintf(stderr,
+			fprintf(stderr,
 				_("%s: panic: Invalid l_value %d\n"),
 				progname, lp->l_value);
 			exit(EXIT_FAILURE);
-	} else if (sscanf(cp, scheck(cp, "%"SCNdZIC), &rp->r_hiyear) != 1) {
+	} else if (sscanf(cp, "%"SCNdZIC"%c", &rp->r_hiyear, &xs) != 1) {
 		error(_("invalid ending year"));
 		return;
 	}
@@ -1414,7 +1522,7 @@ rulesub(register struct rule *const rp,
 			}
 			rp->r_wday = lp->l_value;
 		}
-		if (sscanf(ep, scheck(ep, "%d"), &rp->r_dayofmonth) != 1 ||
+		if (sscanf(ep, "%d%c", &rp->r_dayofmonth, &xs) != 1 ||
 			rp->r_dayofmonth <= 0 ||
 			(rp->r_dayofmonth > len_months[1][rp->r_month])) {
 				error(_("invalid day of month"));
@@ -1453,7 +1561,7 @@ puttzcode(const int_fast32_t val, FILE *const fp)
 	char	buf[4];
 
 	convert(val, buf);
-	(void) fwrite(buf, sizeof buf, 1, fp);
+	fwrite(buf, sizeof buf, 1, fp);
 }
 
 static void
@@ -1462,7 +1570,7 @@ puttzcode64(const zic_t val, FILE *const fp)
 	char	buf[8];
 
 	convert64(val, buf);
-	(void) fwrite(buf, sizeof buf, 1, fp);
+	fwrite(buf, sizeof buf, 1, fp);
 }
 
 static int
@@ -1474,7 +1582,7 @@ atcomp(const void *avp, const void *bvp)
 	return (a < b) ? -1 : (a > b);
 }
 
-static int
+static bool
 is32(const zic_t x)
 {
 	return INT32_MIN <= x && x <= INT32_MAX;
@@ -1488,7 +1596,7 @@ writezone(const char *const name, const char *const string, char version)
 	register int			leapcnt32, leapi32;
 	register int			timecnt32, timei32;
 	register int			pass;
-	static char *			fullname;
+	char *				fullname;
 	static const struct tzhead	tzh0;
 	static struct tzhead		tzh;
 	zic_t *ats = emalloc(size_product(timecnt, sizeof *ats + 1));
@@ -1499,7 +1607,7 @@ writezone(const char *const name, const char *const string, char version)
 	** Sort.
 	*/
 	if (timecnt > 1)
-		(void) qsort(attypes, timecnt, sizeof *attypes, atcomp);
+		qsort(attypes, timecnt, sizeof *attypes, atcomp);
 	/*
 	** Optimize.
 	*/
@@ -1561,7 +1669,7 @@ writezone(const char *const name, const char *const string, char version)
 		++timei32;
 	}
 	/*
-	** Output an INT32_MIN "transition" if appropriate--see below.
+	** Output an INT32_MIN "transition" if appropriate; see below.
 	*/
 	if (timei32 > 0 && ats[timei32] > INT32_MIN) {
 		--timei32;
@@ -1573,26 +1681,24 @@ writezone(const char *const name, const char *const string, char version)
 		--leapcnt32;
 		++leapi32;
 	}
-	fullname = erealloc(fullname,
-			    strlen(directory) + 1 + strlen(name) + 1);
-	(void) sprintf(fullname, "%s/%s", directory, name);
+	fullname = relname(directory, name);
 	/*
 	** Remove old file, if any, to snap links.
 	*/
-	if (!itsdir(fullname) && remove(fullname) != 0 && errno != ENOENT) {
+	if (itsdir(fullname) <= 0 && remove(fullname) != 0 && errno != ENOENT) {
 		const char *e = strerror(errno);
 
-		(void) fprintf(stderr, _("%s: Can't remove %s: %s\n"),
+		fprintf(stderr, _("%s: Can't remove %s: %s\n"),
 			progname, fullname, e);
 		exit(EXIT_FAILURE);
 	}
 	if ((fp = fopen(fullname, "wb")) == NULL) {
-		if (mkdirs(fullname) != 0)
+		if (! mkdirs(fullname))
 			exit(EXIT_FAILURE);
 		if ((fp = fopen(fullname, "wb")) == NULL) {
 			const char *e = strerror(errno);
 
-			(void) fprintf(stderr, _("%s: Can't create %s: %s\n"),
+			fprintf(stderr, _("%s: Can't create %s: %s\n"),
 				progname, fullname, e);
 			exit(EXIT_FAILURE);
 		}
@@ -1606,7 +1712,7 @@ writezone(const char *const name, const char *const string, char version)
 		register int	thistypecnt;
 		char		thischars[TZ_MAX_CHARS];
 		char		thischarcnt;
-		int 		indmap[TZ_MAX_CHARS];
+		int		indmap[TZ_MAX_CHARS];
 
 		if (pass == 1) {
 			thistimei = timei32;
@@ -1629,16 +1735,16 @@ writezone(const char *const name, const char *const string, char version)
 			** (32- or 64-bit) window.
 			*/
 			if (typecnt != 0)
-				writetype[typecnt - 1] = TRUE;
+				writetype[typecnt - 1] = true;
 		} else {
 			for (i = thistimei - 1; i < thistimelim; ++i)
 				if (i >= 0)
-					writetype[types[i]] = TRUE;
+					writetype[types[i]] = true;
 			/*
 			** For America/Godthab and Antarctica/Palmer
 			*/
 			if (thistimei == 0)
-				writetype[0] = TRUE;
+				writetype[0] = true;
 		}
 #ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH
 		/*
@@ -1668,22 +1774,22 @@ writezone(const char *const name, const char *const string, char version)
 					isdsts[mrudst] = -1;
 					type = addtype(gmtoffs[mrudst],
 						&chars[abbrinds[mrudst]],
-						TRUE,
+						true,
 						ttisstds[mrudst],
 						ttisgmts[mrudst]);
-					isdsts[mrudst] = TRUE;
-					writetype[type] = TRUE;
+					isdsts[mrudst] = 1;
+					writetype[type] = true;
 			}
 			if (histd >= 0 && mrustd >= 0 && histd != mrustd &&
 				gmtoffs[histd] != gmtoffs[mrustd]) {
 					isdsts[mrustd] = -1;
 					type = addtype(gmtoffs[mrustd],
 						&chars[abbrinds[mrustd]],
-						FALSE,
+						false,
 						ttisstds[mrustd],
 						ttisgmts[mrustd]);
-					isdsts[mrustd] = FALSE;
-					writetype[type] = TRUE;
+					isdsts[mrustd] = 0;
+					writetype[type] = true;
 			}
 		}
 #endif /* !defined LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH */
@@ -1705,15 +1811,15 @@ writezone(const char *const name, const char *const string, char version)
 				if (strcmp(&thischars[j], thisabbr) == 0)
 					break;
 			if (j == thischarcnt) {
-				(void) strcpy(&thischars[(int) thischarcnt],
+				strcpy(&thischars[(int) thischarcnt],
 					thisabbr);
 				thischarcnt += strlen(thisabbr) + 1;
 			}
 			indmap[abbrinds[i]] = j;
 		}
-#define DO(field)	((void) fwrite(tzh.field, sizeof tzh.field, 1, fp))
+#define DO(field)	fwrite(tzh.field, sizeof tzh.field, 1, fp)
 		tzh = tzh0;
-		(void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
+		strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
 		tzh.tzh_version[0] = version;
 		convert(thistypecnt, tzh.tzh_ttisgmtcnt);
 		convert(thistypecnt, tzh.tzh_ttisstdcnt);
@@ -1735,7 +1841,7 @@ writezone(const char *const name, const char *const string, char version)
 			if (pass == 1)
 				/*
 				** Output an INT32_MIN "transition"
-				** if appropriate--see above.
+				** if appropriate; see above.
 				*/
 				puttzcode(((ats[i] < INT32_MIN) ?
 					INT32_MIN : ats[i]), fp);
@@ -1744,16 +1850,16 @@ writezone(const char *const name, const char *const string, char version)
 			unsigned char	uc;
 
 			uc = typemap[types[i]];
-			(void) fwrite(&uc, sizeof uc, 1, fp);
+			fwrite(&uc, sizeof uc, 1, fp);
 		}
 		for (i = 0; i < typecnt; ++i)
 			if (writetype[i]) {
 				puttzcode(gmtoffs[i], fp);
-				(void) putc(isdsts[i], fp);
-				(void) putc((unsigned char) indmap[abbrinds[i]], fp);
+				putc(isdsts[i], fp);
+				putc((unsigned char) indmap[abbrinds[i]], fp);
 			}
 		if (thischarcnt != 0)
-			(void) fwrite(thischars, sizeof thischars[0],
+			fwrite(thischars, sizeof thischars[0],
 				      thischarcnt, fp);
 		for (i = thisleapi; i < thisleaplim; ++i) {
 			register zic_t	todo;
@@ -1782,54 +1888,88 @@ writezone(const char *const name, const char *const string, char version)
 		}
 		for (i = 0; i < typecnt; ++i)
 			if (writetype[i])
-				(void) putc(ttisstds[i], fp);
+				putc(ttisstds[i], fp);
 		for (i = 0; i < typecnt; ++i)
 			if (writetype[i])
-				(void) putc(ttisgmts[i], fp);
-	}
-	(void) fprintf(fp, "\n%s\n", string);
-	if (ferror(fp) || fclose(fp)) {
-		(void) fprintf(stderr, _("%s: Error writing %s\n"),
-			progname, fullname);
-		exit(EXIT_FAILURE);
+				putc(ttisgmts[i], fp);
 	}
+	fprintf(fp, "\n%s\n", string);
+	close_file(fp, fullname);
 	free(ats);
+	free(fullname);
 }
 
-static void
-doabbr(char *const abbr, const char *const format, const char *const letters,
-       const int isdst, const int doquotes)
+static char const *
+abbroffset(char *buf, zic_t offset)
+{
+  char sign = '+';
+  int seconds, minutes;
+
+  if (offset < 0) {
+    offset = -offset;
+    sign = '-';
+  }
+
+  seconds = offset % SECSPERMIN;
+  offset /= SECSPERMIN;
+  minutes = offset % MINSPERHOUR;
+  offset /= MINSPERHOUR;
+  if (100 <= offset) {
+    error(_("%%z UTC offset magnitude exceeds 99:59:59"));
+    return "%z";
+  } else {
+    char *p = buf;
+    *p++ = sign;
+    *p++ = '0' + offset / 10;
+    *p++ = '0' + offset % 10;
+    if (minutes | seconds) {
+      *p++ = '0' + minutes / 10;
+      *p++ = '0' + minutes % 10;
+      if (seconds) {
+	*p++ = '0' + seconds / 10;
+	*p++ = '0' + seconds % 10;
+      }
+    }
+    *p = '\0';
+    return buf;
+  }
+}
+
+static size_t
+doabbr(char *abbr, struct zone const *zp, char const *letters,
+       zic_t stdoff, bool doquotes)
 {
 	register char *	cp;
 	register char *	slashp;
-	register int	len;
+	register size_t	len;
+	char const *format = zp->z_format;
 
 	slashp = strchr(format, '/');
 	if (slashp == NULL) {
-		if (letters == NULL)
-			(void) strcpy(abbr, format);
-		else	(void) sprintf(abbr, format, letters);
-	} else if (isdst) {
-		(void) strcpy(abbr, slashp + 1);
+	  char letterbuf[PERCENT_Z_LEN_BOUND + 1];
+	  if (zp->z_format_specifier == 'z')
+	    letters = abbroffset(letterbuf, zp->z_gmtoff + stdoff);
+	  else if (!letters)
+	    letters = "%s";
+	  sprintf(abbr, format, letters);
+	} else if (stdoff != 0) {
+		strcpy(abbr, slashp + 1);
 	} else {
-		if (slashp > format)
-			(void) strncpy(abbr, format, slashp - format);
+		memcpy(abbr, format, slashp - format);
 		abbr[slashp - format] = '\0';
 	}
-	if (!doquotes)
-		return;
-	for (cp = abbr; *cp != '\0'; ++cp)
-		if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ", *cp) == NULL &&
-			strchr("abcdefghijklmnopqrstuvwxyz", *cp) == NULL)
-				break;
 	len = strlen(abbr);
+	if (!doquotes)
+		return len;
+	for (cp = abbr; is_alpha(*cp); cp++)
+		continue;
 	if (len > 0 && *cp == '\0')
-		return;
+		return len;
 	abbr[len + 2] = '\0';
 	abbr[len + 1] = '>';
-	for ( ; len > 0; --len)
-		abbr[len] = abbr[len - 1];
+	memmove(abbr + 1, abbr, len);
 	abbr[0] = '<';
+	return len + 2;
 }
 
 static void
@@ -1847,11 +1987,12 @@ stringoffset(char *result, zic_t offset)
 	register int	hours;
 	register int	minutes;
 	register int	seconds;
+	bool negative = offset < 0;
+	int len = negative;
 
-	result[0] = '\0';
-	if (offset < 0) {
-		(void) strcpy(result, "-");
+	if (negative) {
 		offset = -offset;
+		result[0] = '-';
 	}
 	seconds = offset % SECSPERMIN;
 	offset /= SECSPERMIN;
@@ -1860,15 +2001,15 @@ stringoffset(char *result, zic_t offset)
 	hours = offset;
 	if (hours >= HOURSPERDAY * DAYSPERWEEK) {
 		result[0] = '\0';
-		return -1;
+		return 0;
 	}
-	(void) sprintf(end(result), "%d", hours);
+	len += sprintf(result + len, "%d", hours);
 	if (minutes != 0 || seconds != 0) {
-		(void) sprintf(end(result), ":%02d", minutes);
+		len += sprintf(result + len, ":%02d", minutes);
 		if (seconds != 0)
-			(void) sprintf(end(result), ":%02d", seconds);
+			len += sprintf(result + len, ":%02d", seconds);
 	}
-	return 0;
+	return len;
 }
 
 static int
@@ -1878,7 +2019,6 @@ stringrule(char *result, const struct rule *const rp, const zic_t dstoff,
 	register zic_t	tod = rp->r_tod;
 	register int	compat = 0;
 
-	result = end(result);
 	if (rp->r_dycode == DC_DOM) {
 		register int	month, total;
 
@@ -1889,9 +2029,9 @@ stringrule(char *result, const struct rule *const rp, const zic_t dstoff,
 			total += len_months[0][month];
 		/* Omit the "J" in Jan and Feb, as that's shorter.  */
 		if (rp->r_month <= 1)
-		  (void) sprintf(result, "%d", total + rp->r_dayofmonth - 1);
+		  result += sprintf(result, "%d", total + rp->r_dayofmonth - 1);
 		else
-		  (void) sprintf(result, "J%d", total + rp->r_dayofmonth);
+		  result += sprintf(result, "J%d", total + rp->r_dayofmonth);
 	} else {
 		register int	week;
 		register int	wday = rp->r_wday;
@@ -1918,16 +2058,16 @@ stringrule(char *result, const struct rule *const rp, const zic_t dstoff,
 		} else	return -1;	/* "cannot happen" */
 		if (wday < 0)
 			wday += DAYSPERWEEK;
-		(void) sprintf(result, "M%d.%d.%d",
-			rp->r_month + 1, week, wday);
+		result += sprintf(result, "M%d.%d.%d",
+				  rp->r_month + 1, week, wday);
 	}
 	if (rp->r_todisgmt)
 		tod += gmtoff;
 	if (rp->r_todisstd && rp->r_stdoff == 0)
 		tod += dstoff;
 	if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
-		(void) strcat(result, "/");
-		if (stringoffset(end(result), tod) != 0)
+		*result++ = '/';
+		if (! stringoffset(result, tod))
 			return -1;
 		if (tod < 0) {
 			if (compat < 2013)
@@ -1967,6 +2107,8 @@ stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
 	register const char *		abbrvar;
 	register int			compat = 0;
 	register int			c;
+	size_t				len;
+	int				offsetlen;
 	struct rule			stdr, dstr;
 
 	result[0] = '\0';
@@ -2016,14 +2158,14 @@ stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
 			dstr.r_dycode = DC_DOM;
 			dstr.r_dayofmonth = 1;
 			dstr.r_tod = 0;
-			dstr.r_todisstd = dstr.r_todisgmt = FALSE;
+			dstr.r_todisstd = dstr.r_todisgmt = false;
 			dstr.r_stdoff = stdrp->r_stdoff;
 			dstr.r_abbrvar = stdrp->r_abbrvar;
 			stdr.r_month = TM_DECEMBER;
 			stdr.r_dycode = DC_DOM;
 			stdr.r_dayofmonth = 31;
 			stdr.r_tod = SECSPERDAY + stdrp->r_stdoff;
-			stdr.r_todisstd = stdr.r_todisgmt = FALSE;
+			stdr.r_todisstd = stdr.r_todisgmt = false;
 			stdr.r_stdoff = 0;
 			stdr.r_abbrvar
 			  = (stdabbrrp ? stdabbrrp->r_abbrvar : "");
@@ -2034,30 +2176,36 @@ stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
 	if (stdrp == NULL && (zp->z_nrules != 0 || zp->z_stdoff != 0))
 		return -1;
 	abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
-	doabbr(result, zp->z_format, abbrvar, FALSE, TRUE);
-	if (stringoffset(end(result), -zp->z_gmtoff) != 0) {
+	len = doabbr(result, zp, abbrvar, 0, true);
+	offsetlen = stringoffset(result + len, -zp->z_gmtoff);
+	if (! offsetlen) {
 		result[0] = '\0';
 		return -1;
 	}
+	len += offsetlen;
 	if (dstrp == NULL)
 		return compat;
-	doabbr(end(result), zp->z_format, dstrp->r_abbrvar, TRUE, TRUE);
-	if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR)
-		if (stringoffset(end(result),
-			-(zp->z_gmtoff + dstrp->r_stdoff)) != 0) {
-				result[0] = '\0';
-				return -1;
-		}
-	(void) strcat(result, ",");
-	c = stringrule(result, dstrp, dstrp->r_stdoff, zp->z_gmtoff);
+	len += doabbr(result + len, zp, dstrp->r_abbrvar, dstrp->r_stdoff, true);
+	if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR) {
+	  offsetlen = stringoffset(result + len,
+				   -(zp->z_gmtoff + dstrp->r_stdoff));
+	  if (! offsetlen) {
+	    result[0] = '\0';
+	    return -1;
+	  }
+	  len += offsetlen;
+	}
+	result[len++] = ',';
+	c = stringrule(result + len, dstrp, dstrp->r_stdoff, zp->z_gmtoff);
 	if (c < 0) {
 		result[0] = '\0';
 		return -1;
 	}
 	if (compat < c)
 		compat = c;
-	(void) strcat(result, ",");
-	c = stringrule(result, stdrp, dstrp->r_stdoff, zp->z_gmtoff);
+	len += strlen(result + len);
+	result[len++] = ',';
+	c = stringrule(result + len, stdrp, dstrp->r_stdoff, zp->z_gmtoff);
 	if (c < 0) {
 		result[0] = '\0';
 		return -1;
@@ -2068,28 +2216,28 @@ stringzone(char *result, const struct zone *const zpfirst, const int zonecount)
 }
 
 static void
-outzone(const struct zone * const zpfirst, const int zonecount)
+outzone(const struct zone *zpfirst, int zonecount)
 {
 	register const struct zone *	zp;
 	register struct rule *		rp;
 	register int			i, j;
-	register int			usestart, useuntil;
+	register bool			usestart, useuntil;
 	register zic_t			starttime, untiltime;
 	register zic_t			gmtoff;
 	register zic_t			stdoff;
 	register zic_t			year;
 	register zic_t			startoff;
-	register int			startttisstd;
-	register int			startttisgmt;
+	register bool			startttisstd;
+	register bool			startttisgmt;
 	register int			type;
 	register char *			startbuf;
 	register char *			ab;
 	register char *			envvar;
 	register int			max_abbr_len;
 	register int			max_envvar_len;
-	register int			prodstic; /* all rules are min to max */
+	register bool			prodstic; /* all rules are min to max */
 	register int			compat;
-	register int			do_extend;
+	register bool			do_extend;
 	register char			version;
 
 	max_abbr_len = 2 + max_format_len + max_abbrvar_len;
@@ -2110,8 +2258,8 @@ outzone(const struct zone * const zpfirst, const int zonecount)
 	** Thanks to Earl Chew
 	** for noting the need to unconditionally initialize startttisstd.
 	*/
-	startttisstd = FALSE;
-	startttisgmt = FALSE;
+	startttisstd = false;
+	startttisgmt = false;
 	min_year = max_year = EPOCH_YEAR;
 	if (leapseen) {
 		updateminmax(leapminyear);
@@ -2128,7 +2276,7 @@ outzone(const struct zone * const zpfirst, const int zonecount)
 			if (rp->r_hiwasnum)
 				updateminmax(rp->r_hiyear);
 			if (rp->r_lowasnum || rp->r_hiwasnum)
-				prodstic = FALSE;
+				prodstic = false;
 		}
 	}
 	/*
@@ -2208,14 +2356,13 @@ outzone(const struct zone * const zpfirst, const int zonecount)
 		startoff = zp->z_gmtoff;
 		if (zp->z_nrules == 0) {
 			stdoff = zp->z_stdoff;
-			doabbr(startbuf, zp->z_format,
-			       NULL, stdoff != 0, FALSE);
+			doabbr(startbuf, zp, NULL, stdoff, false);
 			type = addtype(oadd(zp->z_gmtoff, stdoff),
 				startbuf, stdoff != 0, startttisstd,
 				startttisgmt);
 			if (usestart) {
 				addtt(starttime, type);
-				usestart = FALSE;
+				usestart = false;
 			} else	addtt(big_bang_time, type);
 		} else for (year = min_year; year <= max_year; ++year) {
 			if (useuntil && year > zp->z_untilrule.r_hiyear)
@@ -2276,42 +2423,51 @@ outzone(const struct zone * const zpfirst, const int zonecount)
 					if (k < 0 || jtime < ktime) {
 						k = j;
 						ktime = jtime;
+					} else if (jtime == ktime) {
+					  char const *dup_rules_msg =
+					    _("two rules for same instant");
+					  eats(zp->z_filename, zp->z_linenum,
+					       rp->r_filename, rp->r_linenum);
+					  warning("%s", dup_rules_msg);
+					  rp = &zp->z_rules[k];
+					  eats(zp->z_filename, zp->z_linenum,
+					       rp->r_filename, rp->r_linenum);
+					  error("%s", dup_rules_msg);
 					}
 				}
 				if (k < 0)
 					break;	/* go on to next year */
 				rp = &zp->z_rules[k];
-				rp->r_todo = FALSE;
+				rp->r_todo = false;
 				if (useuntil && ktime >= untiltime)
 					break;
 				stdoff = rp->r_stdoff;
 				if (usestart && ktime == starttime)
-					usestart = FALSE;
+					usestart = false;
 				if (usestart) {
 					if (ktime < starttime) {
 						startoff = oadd(zp->z_gmtoff,
 							stdoff);
-						doabbr(startbuf, zp->z_format,
+						doabbr(startbuf, zp,
 							rp->r_abbrvar,
-							rp->r_stdoff != 0,
-							FALSE);
+							rp->r_stdoff,
+							false);
 						continue;
 					}
 					if (*startbuf == '\0' &&
 						startoff == oadd(zp->z_gmtoff,
 						stdoff)) {
 							doabbr(startbuf,
-								zp->z_format,
+								zp,
 								rp->r_abbrvar,
-								rp->r_stdoff !=
-								0,
-								FALSE);
+								rp->r_stdoff,
+								false);
 					}
 				}
 				eats(zp->z_filename, zp->z_linenum,
 					rp->r_filename, rp->r_linenum);
-				doabbr(ab, zp->z_format, rp->r_abbrvar,
-					rp->r_stdoff != 0, FALSE);
+				doabbr(ab, zp, rp->r_abbrvar,
+				       rp->r_stdoff, false);
 				offset = oadd(zp->z_gmtoff, rp->r_stdoff);
 				type = addtype(offset, ab, rp->r_stdoff != 0,
 					rp->r_todisstd, rp->r_todisgmt);
@@ -2323,7 +2479,7 @@ outzone(const struct zone * const zpfirst, const int zonecount)
 				zp->z_format != NULL &&
 				strchr(zp->z_format, '%') == NULL &&
 				strchr(zp->z_format, '/') == NULL)
-					(void) strcpy(startbuf, zp->z_format);
+					strcpy(startbuf, zp->z_format);
 			eat(zp->z_filename, zp->z_linenum);
 			if (*startbuf == '\0')
 error(_("can't determine time zone abbreviation to use just after until time"));
@@ -2369,7 +2525,7 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 		if (lastat->at < rpytime(&xr, max_year - 1)) {
 			/*
 			** Create new type code for the redundant entry,
-			** to prevent it being optimised away.
+			** to prevent it being optimized away.
 			*/
 			if (typecnt >= TZ_MAX_TYPES) {
 				error(_("too many local time types"));
@@ -2391,7 +2547,7 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 }
 
 static void
-addtt(const zic_t starttime, int type)
+addtt(zic_t starttime, int type)
 {
 	if (starttime <= big_bang_time ||
 		(timecnt == 1 && attypes[0].at < big_bang_time)) {
@@ -2400,7 +2556,7 @@ addtt(const zic_t starttime, int type)
 		ttisstds[0] = ttisstds[type];
 		ttisgmts[0] = ttisgmts[type];
 		if (abbrinds[type] != 0)
-			(void) strcpy(chars, &chars[abbrinds[type]]);
+			strcpy(chars, &chars[abbrinds[type]]);
 		abbrinds[0] = 0;
 		charcnt = strlen(chars) + 1;
 		typecnt = 1;
@@ -2414,23 +2570,10 @@ addtt(const zic_t starttime, int type)
 }
 
 static int
-addtype(const zic_t gmtoff, const char *const abbr, const int isdst,
-	const int ttisstd, const int ttisgmt)
+addtype(zic_t gmtoff, char const *abbr, bool isdst, bool ttisstd, bool ttisgmt)
 {
 	register int	i, j;
 
-	if (isdst != TRUE && isdst != FALSE) {
-		error(_("internal error - addtype called with bad isdst"));
-		exit(EXIT_FAILURE);
-	}
-	if (ttisstd != TRUE && ttisstd != FALSE) {
-		error(_("internal error - addtype called with bad ttisstd"));
-		exit(EXIT_FAILURE);
-	}
-	if (ttisgmt != TRUE && ttisgmt != FALSE) {
-		error(_("internal error - addtype called with bad ttisgmt"));
-		exit(EXIT_FAILURE);
-	}
 	/*
 	** See if there's already an entry for this zone type.
 	** If so, just return its index.
@@ -2470,7 +2613,7 @@ addtype(const zic_t gmtoff, const char *const abbr, const int isdst,
 }
 
 static void
-leapadd(const zic_t t, const int positive, const int rolling, int count)
+leapadd(zic_t t, bool positive, int rolling, int count)
 {
 	register int	i, j;
 
@@ -2514,64 +2657,106 @@ adjleap(void)
 	}
 }
 
-static int
-yearistype(const int year, const char *const type)
+static bool
+yearistype(int year, const char *type)
 {
 	static char *	buf;
 	int		result;
 
 	if (type == NULL || *type == '\0')
-		return TRUE;
+		return true;
 	buf = erealloc(buf, 132 + strlen(yitcommand) + strlen(type));
-	(void) sprintf(buf, "%s %d %s", yitcommand, year, type);
+	sprintf(buf, "%s %d %s", yitcommand, year, type);
 	result = system(buf);
 	if (WIFEXITED(result)) switch (WEXITSTATUS(result)) {
 		case 0:
-			return TRUE;
+			return true;
 		case 1:
-			return FALSE;
+			return false;
 	}
 	error(_("Wild result from command execution"));
-	(void) fprintf(stderr, _("%s: command was '%s', result was %d\n"),
+	fprintf(stderr, _("%s: command was '%s', result was %d\n"),
 		progname, buf, result);
 	for ( ; ; )
 		exit(EXIT_FAILURE);
 }
 
-static int
-lowerit(int a)
+/* Is A a space character in the C locale?  */
+static bool
+is_space(char a)
+{
+	switch (a) {
+	  default:
+		return false;
+	  case ' ': case '\f': case '\n': case '\r': case '\t': case '\v':
+		return true;
+	}
+}
+
+/* Is A an alphabetic character in the C locale?  */
+static bool
+is_alpha(char a)
 {
-	a = (unsigned char) a;
-	return (isascii(a) && isupper(a)) ? tolower(a) : a;
+	switch (a) {
+	  default:
+		return false;
+	  case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
+	  case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
+	  case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
+	  case 'V': case 'W': case 'X': case 'Y': case 'Z':
+	  case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
+	  case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
+	  case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
+	  case 'v': case 'w': case 'x': case 'y': case 'z':
+		return true;
+	}
+}
+
+/* If A is an uppercase character in the C locale, return its lowercase
+   counterpart.  Otherwise, return A.  */
+static char
+lowerit(char a)
+{
+	switch (a) {
+	  default: return a;
+	  case 'A': return 'a'; case 'B': return 'b'; case 'C': return 'c';
+	  case 'D': return 'd'; case 'E': return 'e'; case 'F': return 'f';
+	  case 'G': return 'g'; case 'H': return 'h'; case 'I': return 'i';
+	  case 'J': return 'j'; case 'K': return 'k'; case 'L': return 'l';
+	  case 'M': return 'm'; case 'N': return 'n'; case 'O': return 'o';
+	  case 'P': return 'p'; case 'Q': return 'q'; case 'R': return 'r';
+	  case 'S': return 's'; case 'T': return 't'; case 'U': return 'u';
+	  case 'V': return 'v'; case 'W': return 'w'; case 'X': return 'x';
+	  case 'Y': return 'y'; case 'Z': return 'z';
+	}
 }
 
 /* case-insensitive equality */
-static ATTRIBUTE_PURE int
+static ATTRIBUTE_PURE bool
 ciequal(register const char *ap, register const char *bp)
 {
 	while (lowerit(*ap) == lowerit(*bp++))
 		if (*ap++ == '\0')
-			return TRUE;
-	return FALSE;
+			return true;
+	return false;
 }
 
-static ATTRIBUTE_PURE int
+static ATTRIBUTE_PURE bool
 itsabbr(register const char *abbr, register const char *word)
 {
 	if (lowerit(*abbr) != lowerit(*word))
-		return FALSE;
+		return false;
 	++word;
 	while (*++abbr != '\0')
 		do {
 			if (*word == '\0')
-				return FALSE;
+				return false;
 		} while (lowerit(*word++) != lowerit(*abbr));
-	return TRUE;
+	return true;
 }
 
 static ATTRIBUTE_PURE const struct lookup *
-byword(register const char *const word,
-       register const struct lookup *const table)
+byword(const char *word, const struct lookup *table)
 {
 	register const struct lookup *	foundlp;
 	register const struct lookup *	lp;
@@ -2609,8 +2794,7 @@ getfields(register char *cp)
 	array = emalloc(size_product(strlen(cp) + 1, sizeof *array));
 	nsubs = 0;
 	for ( ; ; ) {
-		while (isascii((unsigned char) *cp) &&
-			isspace((unsigned char) *cp))
+		while (is_space(*cp))
 				++cp;
 		if (*cp == '\0' || *cp == '#')
 			break;
@@ -2627,9 +2811,8 @@ getfields(register char *cp)
 						));
 					exit(1);
 				}
-		} while (*cp != '\0' && *cp != '#' &&
-			(!isascii(*cp) || !isspace((unsigned char) *cp)));
-		if (isascii(*cp) && isspace((unsigned char) *cp))
+		} while (*cp && *cp != '#' && !is_space(*cp));
+		if (is_space(*cp))
 			++cp;
 		*dp = '\0';
 	}
@@ -2637,37 +2820,47 @@ getfields(register char *cp)
 	return array;
 }
 
+static _Noreturn void
+time_overflow(void)
+{
+  error(_("time overflow"));
+  exit(EXIT_FAILURE);
+}
+
 static ATTRIBUTE_PURE zic_t
-oadd(const zic_t t1, const zic_t t2)
+oadd(zic_t t1, zic_t t2)
 {
-	if (t1 < 0 ? t2 < ZIC_MIN - t1 : ZIC_MAX - t1 < t2) {
-		error(_("time overflow"));
-		exit(EXIT_FAILURE);
-	}
+	if (t1 < 0 ? t2 < ZIC_MIN - t1 : ZIC_MAX - t1 < t2)
+	  time_overflow();
 	return t1 + t2;
 }
 
 static ATTRIBUTE_PURE zic_t
-tadd(const zic_t t1, const zic_t t2)
+tadd(zic_t t1, zic_t t2)
 {
-	if (t1 == max_time && t2 > 0)
-		return max_time;
-	if (t1 == min_time && t2 < 0)
-		return min_time;
-	if (t1 < 0 ? t2 < min_time - t1 : max_time - t1 < t2) {
-		error(_("time overflow"));
-		exit(EXIT_FAILURE);
-	}
-	return t1 + t2;
+  if (t1 < 0) {
+    if (t2 < min_time - t1) {
+      if (t1 != min_time)
+	time_overflow();
+      return min_time;
+    }
+  } else {
+    if (max_time - t1 < t2) {
+      if (t1 != max_time)
+	time_overflow();
+      return max_time;
+    }
+  }
+  return t1 + t2;
 }
 
 /*
-** Given a rule, and a year, compute the date - in seconds since January 1,
-** 1970, 00:00 LOCAL time - in that year that the rule refers to.
+** Given a rule, and a year, compute the date (in seconds since January 1,
+** 1970, 00:00 LOCAL time) in that year that the rule refers to.
 */
 
 static zic_t
-rpytime(register const struct rule *const rp, register const zic_t wantedy)
+rpytime(const struct rule *rp, zic_t wantedy)
 {
 	register int	m, i;
 	register zic_t	dayoff;			/* with a nod to Margaret O. */
@@ -2735,7 +2928,7 @@ rpytime(register const struct rule *const rp, register const zic_t wantedy)
 			}
 		if (i < 0 || i >= len_months[isleap(y)][m]) {
 			if (noise)
-				warning(_("rule goes past start/end of month--\
+				warning(_("rule goes past start/end of month; \
 will not work with pre-2004 versions of zic"));
 		}
 	}
@@ -2748,7 +2941,7 @@ will not work with pre-2004 versions of zic"));
 }
 
 static void
-newabbr(const char *const string)
+newabbr(const char *string)
 {
 	register int	i;
 
@@ -2756,29 +2949,15 @@ newabbr(const char *const string)
 		register const char *	cp;
 		const char *		mp;
 
-		/*
-		** Want one to ZIC_MAX_ABBR_LEN_WO_WARN alphabetics
-		** optionally followed by a + or - and a number from 1 to 14.
-		*/
 		cp = string;
 		mp = NULL;
-		while (isascii((unsigned char) *cp) &&
-			isalpha((unsigned char) *cp))
+		while (is_alpha(*cp) || ('0' <= *cp && *cp <= '9')
+		       || *cp == '-' || *cp == '+')
 				++cp;
-		if (cp - string == 0)
-mp = _("time zone abbreviation lacks alphabetic at start");
 		if (noise && cp - string < 3)
-mp = _("time zone abbreviation has fewer than 3 alphabetics");
+		  mp = _("time zone abbreviation has fewer than 3 characters");
 		if (cp - string > ZIC_MAX_ABBR_LEN_WO_WARN)
-mp = _("time zone abbreviation has too many alphabetics");
-		if (mp == NULL && (*cp == '+' || *cp == '-')) {
-			++cp;
-			if (isascii((unsigned char) *cp) &&
-				isdigit((unsigned char) *cp))
-					if (*cp++ == '1' &&
-						*cp >= '0' && *cp <= '4')
-							++cp;
-		}
+		  mp = _("time zone abbreviation has too many characters");
 		if (*cp != '\0')
 mp = _("time zone abbreviation differs from POSIX standard");
 		if (mp != NULL)
@@ -2789,18 +2968,18 @@ mp = _("time zone abbreviation differs from POSIX standard");
 		error(_("too many, or too long, time zone abbreviations"));
 		exit(EXIT_FAILURE);
 	}
-	(void) strcpy(&chars[charcnt], string);
+	strcpy(&chars[charcnt], string);
 	charcnt += i;
 }
 
-static int
+static bool
 mkdirs(char *argname)
 {
 	register char *	name;
 	register char *	cp;
 
 	if (argname == NULL || *argname == '\0')
-		return 0;
+		return true;
 	cp = name = ecpyalloc(argname);
 	while ((cp = strchr(cp + 1, '/')) != 0) {
 		*cp = '\0';
@@ -2808,37 +2987,29 @@ mkdirs(char *argname)
 		/*
 		** DOS drive specifier?
 		*/
-		if (isalpha((unsigned char) name[0]) &&
-			name[1] == ':' && name[2] == '\0') {
+		if (is_alpha(name[0]) && name[1] == ':' && name[2] == '\0') {
 				*cp = '/';
 				continue;
 		}
 #endif
-		if (!itsdir(name)) {
-			/*
-			** It doesn't seem to exist, so we try to create it.
-			** Creation may fail because of the directory being
-			** created by some other multiprocessor, so we get
-			** to do extra checking.
-			*/
-			if (mkdir(name, MKDIR_UMASK) != 0) {
-				const char *e = strerror(errno);
-
-				if (errno != EEXIST || !itsdir(name)) {
-					(void) fprintf(stderr,
-_("%s: Can't create directory %s: %s\n"),
-						progname, name, e);
-					free(name);
-					return -1;
-				}
+		/*
+		** Try to create it.  It's OK if creation fails because
+		** the directory already exists, perhaps because some
+		** other process just created it.
+		*/
+		if (mkdir(name, MKDIR_UMASK) != 0) {
+			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;
 			}
 		}
 		*cp = '/';
 	}
 	free(name);
-	return 0;
+	return true;
 }
-
-/*
-** UNIX was a registered trademark of The Open Group in 2003.
-*/