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.

1 files changed, 475 insertions, 213 deletions

diff --git a/timezone/zdump.c b/timezone/zdump.c
index c48ac84..063a263 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));
 }