* time/tzfile.c (__tzfile_read): Extend to handle new file format
authorUlrich Drepper <drepper@redhat.com>
Sat, 11 Nov 2006 02:05:42 +0000 (02:05 +0000)
committerUlrich Drepper <drepper@redhat.com>
Sat, 11 Nov 2006 02:05:42 +0000 (02:05 +0000)
on machines with 64-bit time_t.

* timezone/checktab.awk: Update from tzcode2006o.
* timezone/ialloc.c: Likewise.
* timezone/private.h: Likewise.
* timezone/scheck.: Likewise.
* timezone/tzfile.h: Likewise.
* timezone/tzselect.ksh: Likewise.
* timezone/zdump.c: Likewise.
* timezone/zic.c: Likewise.

ChangeLog
time/tzfile.c
timezone/checktab.awk
timezone/ialloc.c
timezone/private.h
timezone/scheck.c
timezone/tzfile.h
timezone/tzselect.ksh
timezone/zdump.c
timezone/zic.c

index 71207b9..72f7d5c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,17 @@
 2006-11-10  Ulrich Drepper  <drepper@redhat.com>
 
+       * time/tzfile.c (__tzfile_read): Extend to handle new file format
+       on machines with 64-bit time_t.
+
+       * timezone/checktab.awk: Update from tzcode2006o.
+       * timezone/ialloc.c: Likewise.
+       * timezone/private.h: Likewise.
+       * timezone/scheck.: Likewise.
+       * timezone/tzfile.h: Likewise.
+       * timezone/tzselect.ksh: Likewise.
+       * timezone/zdump.c: Likewise.
+       * timezone/zic.c: Likewise.
+
        [BZ #3483]
        * elf/ldconfig.c (main): Call setlocale and textdomain.
        Patch mostly by Benno Schulenberg <bensberg@justemail.net>.
index e95fd55..295f0aa 100644 (file)
@@ -1,4 +1,5 @@
-/* Copyright (C) 1991-1993,1995-2001,2003,2004 Free Software Foundation, Inc.
+/* Copyright (C) 1991-1993,1995-2001,2003,2004,2006
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -71,24 +72,34 @@ static inline int
 __attribute ((always_inline))
 decode (const void *ptr)
 {
-  if ((BYTE_ORDER == BIG_ENDIAN) && sizeof (int) == 4)
+  if (BYTE_ORDER == BIG_ENDIAN && sizeof (int) == 4)
     return *(const int *) ptr;
-  else if (BYTE_ORDER == LITTLE_ENDIAN && sizeof (int) == 4)
+  if (sizeof (int) == 4)
     return bswap_32 (*(const int *) ptr);
-  else
-    {
-      const unsigned char *p = ptr;
-      int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;
 
-      result = (result << 8) | *p++;
-      result = (result << 8) | *p++;
-      result = (result << 8) | *p++;
-      result = (result << 8) | *p++;
+  const unsigned char *p = ptr;
+  int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;
 
-      return result;
-    }
+  result = (result << 8) | *p++;
+  result = (result << 8) | *p++;
+  result = (result << 8) | *p++;
+  result = (result << 8) | *p++;
+
+  return result;
 }
 
+
+static inline int64_t
+__attribute ((always_inline))
+decode64 (const void *ptr)
+{
+  if ((BYTE_ORDER == BIG_ENDIAN))
+    return *(const int64_t *) ptr;
+
+  return bswap_64 (*(const int64_t *) ptr);
+}
+
+
 void
 __tzfile_read (const char *file, size_t extra, char **extrap)
 {
@@ -102,6 +113,10 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   size_t types_idx;
   size_t leaps_idx;
   int was_using_tzfile = __use_tzfile;
+  int trans_width = 4;
+
+  if (sizeof (time_t) != 4 && sizeof (time_t) != 8)
+    abort ();
 
   __use_tzfile = 0;
 
@@ -185,8 +200,10 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   /* No threads reading this stream.  */
   __fsetlocking (f, FSETLOCKING_BYCALLER);
 
+ read_again:
   if (__builtin_expect (fread_unlocked ((void *) &tzhead, sizeof (tzhead),
-                                       1, f) != 1, 0))
+                                       1, f) != 1, 0)
+      || memcmp (tzhead.tzh_magic, TZ_MAGIC, sizeof (tzhead.tzh_magic)) != 0)
     goto lose;
 
   num_transitions = (size_t) decode (tzhead.tzh_timecnt);
@@ -196,6 +213,26 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt);
   num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt);
 
+  /* For platforms with 64-bit time_t we use the new format if available.  */
+  if (sizeof (time_t) == 8 && trans_width == 4
+      && tzhead.tzh_version[0] != '\0')
+    {
+      /* We use the 8-byte format.  */
+      trans_width = 8;
+
+      /* Position the stream before the second header.  */
+      size_t to_skip = (num_transitions * (4 + 1)
+                       + num_types * 6
+                       + chars
+                       + num_leaps * 8
+                       + num_isstd
+                       + num_isgmt);
+      if (fseek (f, to_skip, SEEK_CUR) != 0)
+       goto lose;
+
+      goto read_again;
+    }
+
   total_size = num_transitions * (sizeof (time_t) + 1);
   total_size = ((total_size + __alignof__ (struct ttinfo) - 1)
                & ~(__alignof__ (struct ttinfo) - 1));
@@ -205,10 +242,10 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
                & ~(__alignof__ (struct leap) - 1));
   leaps_idx = total_size;
   total_size += num_leaps * sizeof (struct leap);
-  /* This is for the extra memory required by the caller.  */
-  total_size += extra;
 
-  transitions = (time_t *) malloc (total_size);
+  /* Allocate enough memory including the extra block requested by the
+     caller.  */
+  transitions = (time_t *) malloc (total_size + extra);
   if (transitions == NULL)
     goto lose;
 
@@ -220,14 +257,11 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   if (extra > 0)
     *extrap = (char *) &leaps[num_leaps];
 
-  if (sizeof (time_t) < 4)
-    abort ();
-
-  if (sizeof (time_t) == 4)
+  if (sizeof (time_t) == 4 || trans_width == 8)
     {
-      if (__builtin_expect (fread_unlocked (transitions, 1,
-                                           (4 + 1) * num_transitions, f)
-                           != (4 + 1) * num_transitions, 0))
+      if (__builtin_expect (fread_unlocked (transitions, trans_width + 1,
+                                           num_transitions, f)
+                           != num_transitions, 0))
        goto lose;
     }
   else
@@ -245,7 +279,7 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
     if (__builtin_expect (type_idxs[i] >= num_types, 0))
       goto lose;
 
-  if (BYTE_ORDER != BIG_ENDIAN || sizeof (time_t) != 4)
+  if (BYTE_ORDER != BIG_ENDIAN || (sizeof (time_t) == 8 && trans_width == 4))
     {
       /* Decode the transition times, stored as 4-byte integers in
         network (big-endian) byte order.  We work from the end of
@@ -255,6 +289,13 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
       while (i-- > 0)
        transitions[i] = decode ((char *) transitions + i * 4);
     }
+  else if (BYTE_ORDER != BIG_ENDIAN && sizeof (time_t) == 8)
+    {
+      /* Decode the transition times, stored as 8-byte integers in
+        network (big-endian) byte order.  */
+      for (i = 0; i < num_transitions; ++i)
+       transitions[i] = decode64 ((char *) transitions + i * 8);
+    }
 
   for (i = 0; i < num_types; ++i)
     {
@@ -280,13 +321,16 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
 
   for (i = 0; i < num_leaps; ++i)
     {
-      unsigned char x[4];
-      if (__builtin_expect (fread_unlocked (x, 1, sizeof (x), f) != sizeof (x),
-                           0))
+      unsigned char x[8];
+      if (__builtin_expect (fread_unlocked (x, 1, trans_width, f)
+                           != trans_width, 0))
        goto lose;
-      leaps[i].transition = (time_t) decode (x);
-      if (__builtin_expect (fread_unlocked (x, 1, sizeof (x), f) != sizeof (x),
-                           0))
+      if (sizeof (time_t) == 4 || trans_width == 4)
+       leaps[i].transition = (time_t) decode (x);
+      else
+       leaps[i].transition = (time_t) decode64 (x);
+
+      if (__builtin_expect (fread_unlocked (x, 1, 4, f) != 4, 0))
        goto lose;
       leaps[i].change = (long int) decode (x);
     }
@@ -311,6 +355,12 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   while (i < num_types)
     types[i++].isgmt = 0;
 
+  /* XXX When a version 2 file is available it can contain a POSIX TZ-style
+     formatted string which specifies how times past the last one specified
+     are supposed to be handled.  We might want to handle this at some
+     point.  But it might be overhead since most/all? files have an
+     open-ended last entry.  */
+
   fclose (f);
 
   /* First "register" all timezone names.  */
index 6d53214..80ad7d5 100644 (file)
@@ -1,6 +1,6 @@
 # Check tz tables for consistency.
 
-# @(#)checktab.awk     1.7
+# @(#)checktab.awk     8.1
 
 # Contributed by Paul Eggert.
 
index 8a0c701..1fc2035 100644 (file)
@@ -1,6 +1,11 @@
+/*
+** This file is in the public domain, so clarified as of
+** 2006-07-17 by Arthur David Olson.
+*/
+
 #ifndef lint
 #ifndef NOID
-static char    elsieid[] = "@(#)ialloc.c       8.29";
+static char    elsieid[] = "@(#)ialloc.c       8.30";
 #endif /* !defined NOID */
 #endif /* !defined lint */
 
index d9f232c..2837b70 100644 (file)
@@ -21,7 +21,7 @@
 
 #ifndef lint
 #ifndef NOID
-static char    privatehid[] = "@(#)private.h   7.55";
+static char    privatehid[] = "@(#)private.h   8.2";
 #endif /* !defined NOID */
 #endif /* !defined lint */
 
@@ -89,7 +89,7 @@ static char   privatehid[] = "@(#)private.h   7.55";
 #include "stdio.h"
 #include "errno.h"
 #include "string.h"
-#include "limits.h"    /* for CHAR_BIT */
+#include "limits.h"    /* for CHAR_BIT et al. */
 #include "time.h"
 #include "stdlib.h"
 
@@ -125,20 +125,51 @@ static char       privatehid[] = "@(#)private.h   7.55";
 #define is_digit(c) ((unsigned)(c) - '0' <= 9)
 
 /*
+** Define HAVE_STDINT_H's default value here, rather than at the
+** start, since __GLIBC__'s value depends on previously-included
+** files.
+** (glibc 2.1 and later have stdint.h, even with pre-C99 compilers.)
+*/
+#ifndef HAVE_STDINT_H
+#define HAVE_STDINT_H \
+       (199901 <= __STDC_VERSION__ || \
+       2 < (__GLIBC__ + (0 < __GLIBC_MINOR__)))
+#endif /* !defined HAVE_STDINT_H */
+
+#if HAVE_STDINT_H
+#include "stdint.h"
+#endif /* !HAVE_STDINT_H */
+
+#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;
+#else /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
+#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 */
+typedef long           int_fast64_t;
+#endif /* ! (defined LLONG_MAX || defined __LONG_LONG_MAX__) */
+#endif /* !defined INT_FAST64_MAX */
+
+#ifndef INT32_MAX
+#define INT32_MAX 0x7fffffff
+#endif /* !defined INT32_MAX */
+#ifndef INT32_MIN
+#define INT32_MIN (-1 - INT32_MAX)
+#endif /* !defined INT32_MIN */
+
+/*
 ** Workarounds for compilers/systems.
 */
 
 /*
-** SunOS 4.1.1 cc lacks prototypes.
+** If your compiler lacks prototypes, "#define P(x) ()".
 */
 
 #ifndef P
-#ifdef __STDC__
 #define P(x)   x
-#endif /* defined __STDC__ */
-#ifndef __STDC__
-#define P(x)   ()
-#endif /* !defined __STDC__ */
 #endif /* !defined P */
 
 /*
@@ -211,14 +242,14 @@ extern char *     asctime_r();
 ** Private function declarations.
 */
 
-char * icalloc P((int nelem, int elsize));
-char * icatalloc P((char * old, const char * new));
-char * icpyalloc P((const char * string));
-char * imalloc P((int n));
-void * irealloc P((void * pointer, int size));
-void   icfree P((char * pointer));
-void   ifree P((char * pointer));
-const char *scheck P((const char *string, const char *format));
+char *         icalloc P((int nelem, int elsize));
+char *         icatalloc P((char * old, const char * new));
+char *         icpyalloc P((const char * string));
+char *         imalloc P((int n));
+void *         irealloc P((void * pointer, int size));
+void           icfree P((char * pointer));
+void           ifree P((char * pointer));
+const char *   scheck P((const char * string, const char * format));
 
 /*
 ** Finally, some convenience items.
@@ -310,6 +341,26 @@ char *asctime_r P((struct tm const *, char *));
 char *ctime_r P((time_t const *, char *));
 #endif /* HAVE_INCOMPATIBLE_CTIME_R */
 
+#ifndef YEARSPERREPEAT
+#define YEARSPERREPEAT         400     /* years before a Gregorian repeat */
+#endif /* !defined YEARSPERREPEAT */
+
+/*
+** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
+*/
+
+#ifndef AVGSECSPERYEAR
+#define AVGSECSPERYEAR         31556952L
+#endif /* !defined AVGSECSPERYEAR */
+
+#ifndef SECSPERREPEAT
+#define SECSPERREPEAT          ((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
+#endif /* !defined SECSPERREPEAT */
+#ifndef SECSPERREPEAT_BITS
+#define SECSPERREPEAT_BITS     34      /* ceil(log2(SECSPERREPEAT)) */
+#endif /* !defined SECSPERREPEAT_BITS */
+
 /*
 ** UNIX was a registered trademark of The Open Group in 2003.
 */
index bc15637..74d9b07 100644 (file)
@@ -1,6 +1,11 @@
+/*
+** This file is in the public domain, so clarified as of
+** 2006-07-17 by Arthur David Olson.
+*/
+
 #ifndef lint
 #ifndef NOID
-static char    elsieid[] = "@(#)scheck.c       8.17";
+static char    elsieid[] = "@(#)scheck.c       8.19";
 #endif /* !defined lint */
 #endif /* !defined NOID */
 
index fb6ca98..3a9eee3 100644 (file)
@@ -21,7 +21,7 @@
 
 #ifndef lint
 #ifndef NOID
-static char    tzfilehid[] = "@(#)tzfile.h     7.18";
+static char    tzfilehid[] = "@(#)tzfile.h     8.1";
 #endif /* !defined NOID */
 #endif /* !defined lint */
 
@@ -49,7 +49,8 @@ static char   tzfilehid[] = "@(#)tzfile.h     7.18";
 
 struct tzhead {
        char    tzh_magic[4];           /* TZ_MAGIC */
-       char    tzh_reserved[16];       /* reserved for future use */
+       char    tzh_version[1];         /* '\0' or '2' as of 2005 */
+       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 */
@@ -84,18 +85,22 @@ struct tzhead {
 */
 
 /*
+** If tzh_version is '2' or greater, the above is followed by a second instance
+** of tzhead and a second instance of the data in which each coded transition
+** time uses 8 rather than 4 chars,
+** then a POSIX-TZ-environment-variable-style string for use in handling
+** instants after the last transition time stored in the file
+** (with nothing between the newlines if there is no POSIX representation for
+** such instants).
+*/
+
+/*
 ** In the current implementation, "tzset()" refuses to deal with files that
 ** exceed any of the limits below.
 */
 
 #ifndef TZ_MAX_TIMES
-/*
-** The TZ_MAX_TIMES value below is enough to handle a bit more than a
-** year's worth of solar time (corrected daily to the nearest second) or
-** 138 years of Pacific Presidential Election time
-** (where there are three time zone transitions every fourth year).
-*/
-#define TZ_MAX_TIMES   370
+#define TZ_MAX_TIMES   1200
 #endif /* !defined TZ_MAX_TIMES */
 
 #ifndef TZ_MAX_TYPES
index f6e28bf..b99af82 100644 (file)
@@ -1,6 +1,6 @@
 #! @KSH@
 
-# '@(#)tzselect.ksh    1.8'
+# '@(#)tzselect.ksh    8.1'
 
 # Ask the user about the time zone, and output the resulting TZ value to stdout.
 # Interact with the user via stderr and stdin.
index d525da1..b5dd09b 100644 (file)
@@ -1,4 +1,4 @@
-static char    elsieid[] = "@(#)zdump.c        7.74";
+static char    elsieid[] = "@(#)zdump.c        8.2";
 
 /*
 ** This code has been made independent of the rest of the time
@@ -15,7 +15,7 @@ static char   elsieid[] = "@(#)zdump.c        7.74";
 #include "ctype.h"     /* for isalpha et al. */
 #ifndef isascii
 #define isascii(x) 1
-#endif
+#endif /* !defined isascii */
 
 #ifndef ZDUMP_LO_YEAR
 #define ZDUMP_LO_YEAR  (-500)
@@ -130,11 +130,7 @@ static char        elsieid[] = "@(#)zdump.c        7.74";
 #endif /* !defined TZ_DOMAIN */
 
 #ifndef P
-#ifdef __STDC__
 #define P(x)   x
-#else /* !defined __STDC__ */
-#define P(x)   ()
-#endif /* !defined __STDC__ */
 #endif /* !defined P */
 
 extern char ** environ;
@@ -389,7 +385,7 @@ _("%s: usage is %s [ --version ] [ -v ] [ -c [loyear,]hiyear ] zonename ...\n"),
        }
        if (fflush(stdout) || ferror(stdout)) {
                (void) fprintf(stderr, "%s: ", progname);
-               (void) perror(_("Error writing to standard output"));
+               (void) perror(_("Error writing standard output"));
                exit(EXIT_FAILURE);
        }
        exit(EXIT_SUCCESS);
@@ -418,14 +414,21 @@ _("%s: use of -v on system with floating time_t other than float or double\n"),
                }
        } else if (0 > (time_t) -1) {
                /*
-               ** time_t is signed.
+               ** time_t is signed.  Assume overflow wraps around.
                */
-               register time_t hibit;
+               time_t t = 0;
+               time_t t1 = 1;
 
-               for (hibit = 1; (hibit * 2) != 0; hibit *= 2)
-                       continue;
-               absolute_min_time = hibit;
-               absolute_max_time = -(hibit + 1);
+               while (t < t1) {
+                       t = t1;
+                       t1 = 2 * t1 + 1;
+               }
+                 
+               absolute_max_time = t;
+               t = -t;
+               absolute_min_time = t - 1;
+               if (t < absolute_min_time)
+                       absolute_min_time = t;
        } else {
                /*
                ** time_t is unsigned.
@@ -468,10 +471,7 @@ const long y;
 }
 
 static time_t
-hunt(name, lot, hit)
-char * name;
-time_t lot;
-time_t hit;
+hunt(char *name, time_t lot, time_t hit)
 {
        time_t                  t;
        long                    diff;
@@ -541,10 +541,7 @@ struct tm *        oldp;
 }
 
 static void
-show(zone, t, v)
-char * zone;
-time_t t;
-int    v;
+show(char *zone, time_t t, int v)
 {
        register struct tm *    tmp;
 
index acb76fb..f7393ea 100644 (file)
@@ -1,15 +1,18 @@
-static char    elsieid[] = "@(#)zic.c  7.128";
-
 /*
-** Regardless of the type of time_t, we do our work using this type.
+** This file is in the public domain, so clarified as of
+** 2006-07-17 by Arthur David Olson.
 */
 
-typedef int    zic_t;
+static char    elsieid[] = "@(#)zic.c  8.7";
 
 #include "private.h"
 #include "locale.h"
 #include "tzfile.h"
 
+#define        ZIC_VERSION     '2'
+
+typedef int_fast64_t   zic_t;
+
 #ifndef ZIC_MAX_ABBR_LEN_WO_WARN
 #define ZIC_MAX_ABBR_LEN_WO_WARN       6
 #endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
@@ -36,6 +39,11 @@ typedef int  zic_t;
 #define isascii(x) 1
 #endif
 
+#define OFFSET_STRLEN_MAXIMUM  (7 + INT_STRLEN_MAXIMUM(long))
+#define RULE_STRLEN_MAXIMUM    8       /* "Mdd.dd.d" */
+
+#define end(cp)        (strchr((cp), '\0'))
+
 struct rule {
        const char *    r_filename;
        int             r_linenum;
@@ -44,6 +52,8 @@ struct rule {
        int             r_loyear;       /* for example, 1986 */
        int             r_hiyear;       /* for example, 1986 */
        const char *    r_yrtype;
+       int             r_lowasnum;
+       int             r_hiwasnum;
 
        int             r_month;        /* 0..11 */
 
@@ -103,9 +113,10 @@ static void        adjleap P((void));
 static void    associate P((void));
 static int     ciequal P((const char * ap, const char * bp));
 static void    convert P((long val, char * buf));
+static void    convert64 P((zic_t val, char * buf));
 static void    dolink P((const char * fromfile, const char * tofile));
 static void    doabbr P((char * abbr, const char * format,
-                       const char * letters, int isdst));
+                       const char * letters, int isdst, int doquotes));
 static void    eat P((const char * name, int num));
 static void    eats P((const char * name, int num,
                        const char * rname, int rnum));
@@ -121,6 +132,7 @@ static void inrule P((char ** fields, int nfields));
 static int     inzcont P((char ** fields, int nfields));
 static int     inzone P((char ** fields, int nfields));
 static int     inzsub P((char ** fields, int nfields, int iscont));
+static int     is32 P((zic_t x));
 static int     itsabbr P((const char * abbr, const char * word));
 static int     itsdir P((const char * name));
 static int     lowerit P((int c));
@@ -130,16 +142,22 @@ static void       newabbr P((const char * abbr));
 static long    oadd P((long t1, long t2));
 static void    outzone P((const struct zone * zp, int ntzones));
 static void    puttzcode P((long code, FILE * fp));
+static void    puttzcode64 P((zic_t code, FILE * fp));
 static int     rcomp P((const void * leftp, const void * rightp));
 static zic_t   rpytime P((const struct rule * rp, int wantedy));
 static void    rulesub P((struct rule * rp,
                        const char * loyearp, const char * hiyearp,
                        const char * typep, const char * monthp,
                        const char * dayp, const char * timep));
+static int     stringoffset P((char * result, long offset));
+static int     stringrule P((char * result, const struct rule * rp,
+                       long dstoff, long gmtoff));
+static void    stringzone P((char * result,
+                       const struct zone * zp, int ntzones));
 static void    setboundaries P((void));
 static zic_t   tadd P((zic_t t1, long t2));
 static void    usage P((void));
-static void    writezone P((const char * name));
+static void    writezone P((const char * name, const char * string));
 static int     yearistype P((int year, const char * type));
 
 #if !HAVE_STRERROR
@@ -150,13 +168,16 @@ static int                charcnt;
 static int             errors;
 static const char *    filename;
 static int             leapcnt;
+static int             leapseen;
+static int             leapminyear;
+static int             leapmaxyear;
 static int             linenum;
+static int             max_abbrvar_len;
+static int             max_format_len;
 static zic_t           max_time;
 static int             max_year;
-static int             max_year_representable;
 static zic_t           min_time;
 static int             min_year;
-static int             min_year_representable;
 static int             noise;
 static const char *    rfilename;
 static int             rlinenum;
@@ -453,7 +474,7 @@ static void
 usage P((void))
 {
        (void) fprintf(stderr, _("%s: usage is %s \
-[ --version ] [ -s ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
+[ --version ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
 \t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n"),
                progname, progname);
        exit(EXIT_FAILURE);
@@ -464,7 +485,6 @@ static const char * lcltime;
 static const char *    directory;
 static const char *    leapsec;
 static const char *    yitcommand;
-static int             sflag = FALSE;
 
 int
 main(argc, argv)
@@ -486,6 +506,11 @@ char *     argv[];
        (void) textdomain(TZ_DOMAIN);
 #endif /* HAVE_GETTEXT */
        progname = argv[0];
+       if (TYPE_BIT(zic_t) < 64) {
+               (void) fprintf(stderr, "%s: %s\n", progname,
+                       _("wild compilation-time specification of zic_t"));
+               exit(EXIT_FAILURE);
+       }
        for (i = 1; i < argc; ++i)
                if (strcmp(argv[i], "--version") == 0) {
                        (void) printf("%s\n", elsieid);
@@ -549,7 +574,7 @@ _("%s: More than one -L option specified\n"),
                                noise = TRUE;
                                break;
                        case 's':
-                               sflag = TRUE;
+                               (void) printf("%s: -s ignored\n", progname);
                                break;
                }
        if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
@@ -671,54 +696,17 @@ warning(_("hard link failed, symbolic link used"));
        ifree(toname);
 }
 
-#ifndef INT_MAX
-#define INT_MAX        ((int) (((unsigned)~0)>>1))
-#endif /* !defined INT_MAX */
-
-#ifndef INT_MIN
-#define INT_MIN        ((int) ~(((unsigned)~0)>>1))
-#endif /* !defined INT_MIN */
-
-/*
-** The tz file format currently allows at most 32-bit quantities.
-** This restriction should be removed before signed 32-bit values
-** wrap around in 2038, but unfortunately this will require a
-** change to the tz file format.
-*/
-
-#define MAX_BITS_IN_FILE       32
-#define TIME_T_BITS_IN_FILE    ((TYPE_BIT(zic_t) < MAX_BITS_IN_FILE) ? \
-                                       TYPE_BIT(zic_t) : MAX_BITS_IN_FILE)
+#define TIME_T_BITS_IN_FILE    64
 
 static void
 setboundaries P((void))
 {
        register int    i;
 
-       if (TYPE_SIGNED(zic_t)) {
-               min_time = -1;
-               for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
-                       min_time *= 2;
-               max_time = -(min_time + 1);
-               if (sflag)
-                       min_time = 0;
-       } else {
-               min_time = 0;
-               max_time = 2 - sflag;
-               for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
-                       max_time *= 2;
-               --max_time;
-       }
-       {
-               time_t  t;
-
-               t = (time_t) min_time;
-               min_year = TM_YEAR_BASE + gmtime(&t)->tm_year;
-               t = (time_t) max_time;
-               max_year = TM_YEAR_BASE + gmtime(&t)->tm_year;
-       }
-       min_year_representable = min_year;
-       max_year_representable = max_year;
+       min_time = -1;
+       for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
+               min_time *= 2;
+       max_time = -(min_time + 1);
 }
 
 static int
@@ -993,6 +981,8 @@ const int           nfields;
                fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
        r.r_name = ecpyalloc(fields[RF_NAME]);
        r.r_abbrvar = ecpyalloc(fields[RF_ABBRVAR]);
+       if (max_abbrvar_len < strlen(r.r_abbrvar))
+               max_abbrvar_len = strlen(r.r_abbrvar);
        rules = (struct rule *) (void *) erealloc((char *) rules,
                (int) ((nrules + 1) * sizeof *rules));
        rules[nrules++] = r;
@@ -1098,6 +1088,8 @@ const int         iscont;
        }
        z.z_rule = ecpyalloc(fields[i_rule]);
        z.z_format = ecpyalloc(fields[i_format]);
+       if (max_format_len < strlen(z.z_format))
+               max_format_len = strlen(z.z_format);
        hasuntil = nfields > i_untilyear;
        if (hasuntil) {
                z.z_untilrule.r_filename = filename;
@@ -1159,6 +1151,11 @@ const int                nfields;
                error(_("invalid leaping year"));
                return;
        }
+       if (!leapseen || leapmaxyear < year)
+               leapmaxyear = year;
+       if (!leapseen || leapminyear > year)
+               leapminyear = year;
+       leapseen = TRUE;
        j = EPOCH_YEAR;
        while (j != year) {
                if (year > j) {
@@ -1313,7 +1310,8 @@ const char * const                timep;
        */
        cp = loyearp;
        lp = byword(cp, begin_years);
-       if (lp != NULL) switch ((int) lp->l_value) {
+       rp->r_lowasnum = lp == NULL;
+       if (!rp->r_lowasnum) switch ((int) lp->l_value) {
                case YR_MINIMUM:
                        rp->r_loyear = INT_MIN;
                        break;
@@ -1328,14 +1326,11 @@ const char * const              timep;
        } else if (sscanf(cp, scheck(cp, "%d"), &rp->r_loyear) != 1) {
                error(_("invalid starting year"));
                return;
-       } else if (noise) {
-               if (rp->r_loyear < min_year_representable)
-                       warning(_("starting year too low to be represented"));
-               else if (rp->r_loyear > max_year_representable)
-                       warning(_("starting year too high to be represented"));
        }
        cp = hiyearp;
-       if ((lp = byword(cp, end_years)) != NULL) switch ((int) lp->l_value) {
+       lp = byword(cp, end_years);
+       rp->r_hiwasnum = lp == NULL;
+       if (!rp->r_hiwasnum) switch ((int) lp->l_value) {
                case YR_MINIMUM:
                        rp->r_hiyear = INT_MIN;
                        break;
@@ -1353,11 +1348,6 @@ const char * const               timep;
        } else if (sscanf(cp, scheck(cp, "%d"), &rp->r_hiyear) != 1) {
                error(_("invalid ending year"));
                return;
-       } else if (noise) {
-               if (rp->r_loyear < min_year_representable)
-                       warning(_("ending year too low to be represented"));
-               else if (rp->r_loyear > max_year_representable)
-                       warning(_("ending year too high to be represented"));
        }
        if (rp->r_loyear > rp->r_hiyear) {
                error(_("starting year greater than ending year"));
@@ -1372,8 +1362,6 @@ const char * const                timep;
                }
                rp->r_yrtype = ecpyalloc(typep);
        }
-       if (rp->r_loyear < min_year && rp->r_loyear > 0)
-               min_year = rp->r_loyear;
        /*
        ** Day work.
        ** Accept things such as:
@@ -1427,13 +1415,25 @@ const long      val;
 char * const   buf;
 {
        register int    i;
-       register long   shift;
+       register int    shift;
 
        for (i = 0, shift = 24; i < 4; ++i, shift -= 8)
                buf[i] = val >> shift;
 }
 
 static void
+convert64(val, buf)
+const zic_t    val;
+char * const   buf;
+{
+       register int    i;
+       register int    shift;
+
+       for (i = 0, shift = 56; i < 8; ++i, shift -= 8)
+               buf[i] = val >> shift;
+}
+
+static void
 puttzcode(val, fp)
 const long     val;
 FILE * const   fp;
@@ -1444,28 +1444,50 @@ FILE * const    fp;
        (void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
 }
 
+static void
+puttzcode64(val, fp)
+const zic_t    val;
+FILE * const   fp;
+{
+       char    buf[8];
+
+       convert64(val, buf);
+       (void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
+}
+
 static int
 atcomp(avp, bvp)
-void * avp;
-void * bvp;
+const void *   avp;
+const void *   bvp;
 {
-       if (((struct attype *) avp)->at < ((struct attype *) bvp)->at)
-               return -1;
-       else if (((struct attype *) avp)->at > ((struct attype *) bvp)->at)
-               return 1;
-       else    return 0;
+       const zic_t     a = ((const struct attype *) avp)->at;
+       const zic_t     b = ((const struct attype *) bvp)->at;
+
+       return (a < b) ? -1 : (a > b);
+}
+
+static int
+is32(x)
+const zic_t    x;
+{
+       return INT32_MIN <= x && x <= INT32_MAX;
 }
 
 static void
-writezone(name)
+writezone(name, string)
 const char * const     name;
+const char * const     string;
 {
-       register FILE *         fp;
-       register int            i, j;
-       static char *           fullname;
-       static struct tzhead    tzh;
-       zic_t                   ats[TZ_MAX_TIMES];
-       unsigned char           types[TZ_MAX_TIMES];
+       register FILE *                 fp;
+       register int                    i, j;
+       register int                    leapcnt32, leapi32;
+       register int                    timecnt32, timei32;
+       register int                    pass;
+       static char *                   fullname;
+       static const struct tzhead      tzh0;
+       static struct tzhead            tzh;
+       zic_t                           ats[TZ_MAX_TIMES];
+       unsigned char                   types[TZ_MAX_TIMES];
 
        /*
        ** Sort.
@@ -1509,6 +1531,36 @@ const char * const       name;
                ats[i] = attypes[i].at;
                types[i] = attypes[i].type;
        }
+       /*
+       ** Correct for leap seconds.
+       */
+       for (i = 0; i < timecnt; ++i) {
+               j = leapcnt;
+               while (--j >= 0)
+                       if (ats[i] > trans[j] - corr[j]) {
+                               ats[i] = tadd(ats[i], corr[j]);
+                               break;
+                       }
+       }
+       /*
+       ** Figure out 32-bit-limited starts and counts.
+       */
+       timecnt32 = timecnt;
+       timei32 = 0;
+       leapcnt32 = leapcnt;
+       leapi32 = 0;
+       while (timecnt32 > 0 && !is32(ats[timecnt32 - 1]))
+               --timecnt32;
+       while (timecnt32 > 0 && !is32(ats[timei32])) {
+               --timecnt32;
+               ++timei32;
+       }
+       while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
+               --leapcnt32;
+       while (leapcnt32 > 0 && !is32(trans[leapi32])) {
+               --leapcnt32;
+               ++leapi32;
+       }
        fullname = erealloc(fullname,
                (int) (strlen(directory) + 1 + strlen(name) + 1));
        (void) sprintf(fullname, "%s/%s", directory, name);
@@ -1533,67 +1585,150 @@ const char * const     name;
                        exit(EXIT_FAILURE);
                }
        }
-       convert(eitol(typecnt), tzh.tzh_ttisgmtcnt);
-       convert(eitol(typecnt), tzh.tzh_ttisstdcnt);
-       convert(eitol(leapcnt), tzh.tzh_leapcnt);
-       convert(eitol(timecnt), tzh.tzh_timecnt);
-       convert(eitol(typecnt), tzh.tzh_typecnt);
-       convert(eitol(charcnt), tzh.tzh_charcnt);
-       (void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
+       for (pass = 1; pass <= 2; ++pass) {
+               register int    thistimei, thistimecnt;
+               register int    thisleapi, thisleapcnt;
+               register int    thistimelim, thisleaplim;
+               int             writetype[TZ_MAX_TIMES];
+               int             typemap[TZ_MAX_TYPES];
+               register int    thistypecnt;
+               char            thischars[TZ_MAX_CHARS];
+               char            thischarcnt;
+               int             indmap[TZ_MAX_CHARS];
+
+               if (pass == 1) {
+                       thistimei = timei32;
+                       thistimecnt = timecnt32;
+                       thisleapi = leapi32;
+                       thisleapcnt = leapcnt32;
+               } else {
+                       thistimei = 0;
+                       thistimecnt = timecnt;
+                       thisleapi = 0;
+                       thisleapcnt = leapcnt;
+               }
+               thistimelim = thistimei + thistimecnt;
+               thisleaplim = thisleapi + thisleapcnt;
+               for (i = 0; i < typecnt; ++i)
+                       writetype[i] = thistimecnt == timecnt;
+               if (thistimecnt == 0) {
+                       /*
+                       ** No transition times fall in the current
+                       ** (32- or 64-bit) window.
+                       */
+                       if (typecnt != 0)
+                               writetype[typecnt - 1] = TRUE;
+               } else {
+                       for (i = thistimei - 1; i < thistimelim; ++i)
+                               if (i >= 0)
+                                       writetype[types[i]] = TRUE;
+                       /*
+                       ** For America/Godthab and Antarctica/Palmer
+                       */
+                       if (thistimei == 0)
+                               writetype[0] = TRUE;
+               }
+               thistypecnt = 0;
+               for (i = 0; i < typecnt; ++i)
+                       typemap[i] = writetype[i] ?  thistypecnt++ : -1;
+               for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i)
+                       indmap[i] = -1;
+               thischarcnt = 0;
+               for (i = 0; i < typecnt; ++i) {
+                       register char * thisabbr;
+
+                       if (!writetype[i])
+                               continue;
+                       if (indmap[abbrinds[i]] >= 0)
+                               continue;
+                       thisabbr = &chars[abbrinds[i]];
+                       for (j = 0; j < thischarcnt; ++j)
+                               if (strcmp(&thischars[j], thisabbr) == 0)
+                                       break;
+                       if (j == thischarcnt) {
+                               (void) strcpy(&thischars[(int) thischarcnt],
+                                       thisabbr);
+                               thischarcnt += strlen(thisabbr) + 1;
+                       }
+                       indmap[abbrinds[i]] = j;
+               }
 #define DO(field)      (void) fwrite((void *) tzh.field, \
                                (size_t) sizeof tzh.field, (size_t) 1, fp)
-       DO(tzh_magic);
-       DO(tzh_reserved);
-       DO(tzh_ttisgmtcnt);
-       DO(tzh_ttisstdcnt);
-       DO(tzh_leapcnt);
-       DO(tzh_timecnt);
-       DO(tzh_typecnt);
-       DO(tzh_charcnt);
+               tzh = tzh0;
+               (void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
+               tzh.tzh_version[0] = ZIC_VERSION;
+               convert(eitol(thistypecnt), tzh.tzh_ttisgmtcnt);
+               convert(eitol(thistypecnt), tzh.tzh_ttisstdcnt);
+               convert(eitol(thisleapcnt), tzh.tzh_leapcnt);
+               convert(eitol(thistimecnt), tzh.tzh_timecnt);
+               convert(eitol(thistypecnt), tzh.tzh_typecnt);
+               convert(eitol(thischarcnt), tzh.tzh_charcnt);
+               DO(tzh_magic);
+               DO(tzh_version);
+               DO(tzh_reserved);
+               DO(tzh_ttisgmtcnt);
+               DO(tzh_ttisstdcnt);
+               DO(tzh_leapcnt);
+               DO(tzh_timecnt);
+               DO(tzh_typecnt);
+               DO(tzh_charcnt);
 #undef DO
-       for (i = 0; i < timecnt; ++i) {
-               j = leapcnt;
-               while (--j >= 0)
-                       if (ats[i] >= trans[j]) {
-                               ats[i] = tadd(ats[i], corr[j]);
-                               break;
-                       }
-               puttzcode((long) ats[i], fp);
-       }
-       if (timecnt > 0)
-               (void) fwrite((void *) types, (size_t) sizeof types[0],
-                       (size_t) timecnt, fp);
-       for (i = 0; i < typecnt; ++i) {
-               puttzcode((long) gmtoffs[i], fp);
-               (void) putc(isdsts[i], fp);
-               (void) putc(abbrinds[i], fp);
-       }
-       if (charcnt != 0)
-               (void) fwrite((void *) chars, (size_t) sizeof chars[0],
-                       (size_t) charcnt, fp);
-       for (i = 0; i < leapcnt; ++i) {
-               if (roll[i]) {
-                       if (timecnt == 0 || trans[i] < ats[0]) {
-                               j = 0;
-                               while (isdsts[j])
-                                       if (++j >= typecnt) {
-                                               j = 0;
-                                               break;
-                                       }
-                       } else {
-                               j = 1;
-                               while (j < timecnt && trans[i] >= ats[j])
-                                       ++j;
-                               j = types[j - 1];
+               for (i = thistimei; i < thistimelim; ++i)
+                       if (pass == 1)
+                               puttzcode((long) ats[i], fp);
+                       else    puttzcode64(ats[i], fp);
+               for (i = thistimei; i < thistimelim; ++i) {
+                       unsigned char   uc;
+
+                       uc = typemap[types[i]];
+                       (void) fwrite((void *) &uc,
+                               (size_t) sizeof uc,
+                               (size_t) 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);
                        }
-                       puttzcode((long) tadd(trans[i], -gmtoffs[j]), fp);
-               } else  puttzcode((long) trans[i], fp);
-               puttzcode((long) corr[i], fp);
-       }
-       for (i = 0; i < typecnt; ++i)
-               (void) putc(ttisstds[i], fp);
-       for (i = 0; i < typecnt; ++i)
-               (void) putc(ttisgmts[i], fp);
+               if (thischarcnt != 0)
+                       (void) fwrite((void *) thischars,
+                               (size_t) sizeof thischars[0],
+                               (size_t) thischarcnt, fp);
+               for (i = thisleapi; i < thisleaplim; ++i) {
+                       register zic_t  todo;
+
+                       if (roll[i]) {
+                               if (timecnt == 0 || trans[i] < ats[0]) {
+                                       j = 0;
+                                       while (isdsts[j])
+                                               if (++j >= typecnt) {
+                                                       j = 0;
+                                                       break;
+                                               }
+                               } else {
+                                       j = 1;
+                                       while (j < timecnt &&
+                                               trans[i] >= ats[j])
+                                                       ++j;
+                                       j = types[j - 1];
+                               }
+                               todo = tadd(trans[i], -gmtoffs[j]);
+                       } else  todo = trans[i];
+                       if (pass == 1)
+                               puttzcode((long) todo, fp);
+                       else    puttzcode64(todo, fp);
+                       puttzcode(corr[i], fp);
+               }
+               for (i = 0; i < typecnt; ++i)
+                       if (writetype[i])
+                               (void) 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);
@@ -1602,21 +1737,223 @@ const char * const     name;
 }
 
 static void
-doabbr(abbr, format, letters, isdst)
+doabbr(abbr, format, letters, isdst, doquotes)
 char * const           abbr;
 const char * const     format;
 const char * const     letters;
 const int              isdst;
+const int              doquotes;
 {
-       if (strchr(format, '/') == NULL) {
+       register char * cp;
+       register char * slashp;
+       register int    len;
+
+       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, strchr(format, '/') + 1);
-       else {
-               (void) strcpy(abbr, format);
-               *strchr(abbr, '/') = '\0';
+       } else if (isdst) {
+               (void) strcpy(abbr, slashp + 1);
+       } else {
+               if (slashp > format)
+                       (void) strncpy(abbr, format,
+                               (unsigned) (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 (len > 0 && *cp == '\0')
+               return;
+       abbr[len + 2] = '\0';
+       abbr[len + 1] = '>';
+       for ( ; len > 0; --len)
+               abbr[len] = abbr[len - 1];
+       abbr[0] = '<';
+}
+
+static void
+updateminmax(x)
+const int      x;
+{
+       if (min_year > x)
+               min_year = x;
+       if (max_year < x)
+               max_year = x;
+}
+
+static int
+stringoffset(result, offset)
+char * result;
+long   offset;
+{
+       register int    hours;
+       register int    minutes;
+       register int    seconds;
+
+       result[0] = '\0';
+       if (offset < 0) {
+               (void) strcpy(result, "-");
+               offset = -offset;
+       }
+       seconds = offset % SECSPERMIN;
+       offset /= SECSPERMIN;
+       minutes = offset % MINSPERHOUR;
+       offset /= MINSPERHOUR;
+       hours = offset;
+       if (hours >= HOURSPERDAY) {
+               result[0] = '\0';
+               return -1;
+       }
+       (void) sprintf(end(result), "%d", hours);
+       if (minutes != 0 || seconds != 0) {
+               (void) sprintf(end(result), ":%02d", minutes);
+               if (seconds != 0)
+                       (void) sprintf(end(result), ":%02d", seconds);
+       }
+       return 0;
+}
+
+static int
+stringrule(result, rp, dstoff, gmtoff)
+char *                         result;
+const struct rule * const      rp;
+const long                     dstoff;
+const long                     gmtoff;
+{
+       register long   tod;
+
+       result = end(result);
+       if (rp->r_dycode == DC_DOM) {
+               register int    month, total;
+
+               if (rp->r_dayofmonth == 29 && rp->r_month == TM_FEBRUARY)
+                       return -1;
+               total = 0;
+               for (month = 0; month < rp->r_month; ++month)
+                       total += len_months[0][month];
+               (void) sprintf(result, "J%d", total + rp->r_dayofmonth);
+       } else {
+               register int    week;
+
+               if (rp->r_dycode == DC_DOWGEQ) {
+                       week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
+                       if ((week - 1) * DAYSPERWEEK + 1 != rp->r_dayofmonth)
+                               return -1;
+               } else if (rp->r_dycode == DC_DOWLEQ) {
+                       if (rp->r_dayofmonth == len_months[1][rp->r_month])
+                               week = 5;
+                       else {
+                               week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
+                               if (week * DAYSPERWEEK - 1 != rp->r_dayofmonth)
+                                       return -1;
+                       }
+               } else  return -1;      /* "cannot happen" */
+               (void) sprintf(result, "M%d.%d.%d",
+                       rp->r_month + 1, week, rp->r_wday);
+       }
+       tod = rp->r_tod;
+       if (rp->r_todisgmt)
+               tod += gmtoff;
+       if (rp->r_todisstd && rp->r_stdoff == 0)
+               tod += dstoff;
+       if (tod < 0) {
+               result[0] = '\0';
+               return -1;
+       }
+       if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
+               (void) strcat(result, "/");
+               if (stringoffset(end(result), tod) != 0)
+                       return -1;
+       }
+       return 0;
+}
+
+static void
+stringzone(result, zpfirst, zonecount)
+char *                         result;
+const struct zone * const      zpfirst;
+const int                      zonecount;
+{
+       register const struct zone *    zp;
+       register struct rule *          rp;
+       register struct rule *          stdrp;
+       register struct rule *          dstrp;
+       register int                    i;
+       register const char *           abbrvar;
+
+       result[0] = '\0';
+       zp = zpfirst + zonecount - 1;
+       stdrp = dstrp = NULL;
+       for (i = 0; i < zp->z_nrules; ++i) {
+               rp = &zp->z_rules[i];
+               if (rp->r_hiwasnum || rp->r_hiyear != INT_MAX)
+                       continue;
+               if (rp->r_yrtype != NULL)
+                       continue;
+               if (rp->r_stdoff == 0) {
+                       if (stdrp == NULL)
+                               stdrp = rp;
+                       else    return;
+               } else {
+                       if (dstrp == NULL)
+                               dstrp = rp;
+                       else    return;
+               }
+       }
+       if (stdrp == NULL && dstrp == NULL) {
+               /*
+               ** There are no rules running through "max".
+               ** Let's find the latest rule.
+               */
+               for (i = 0; i < zp->z_nrules; ++i) {
+                       rp = &zp->z_rules[i];
+                       if (stdrp == NULL || rp->r_hiyear > stdrp->r_hiyear ||
+                               (rp->r_hiyear == stdrp->r_hiyear &&
+                               rp->r_month > stdrp->r_month))
+                                       stdrp = rp;
+               }
+               if (stdrp != NULL && stdrp->r_stdoff != 0)
+                       return; /* We end up in DST (a POSIX no-no). */
+               /*
+               ** Horrid special case: if year is 2037,
+               ** presume this is a zone handled on a year-by-year basis;
+               ** do not try to apply a rule to the zone.
+               */
+               if (stdrp != NULL && stdrp->r_hiyear == 2037)
+                       return;
+       }
+       if (stdrp == NULL && zp->z_nrules != 0)
+               return;
+       abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
+       doabbr(result, zp->z_format, abbrvar, FALSE, TRUE);
+       if (stringoffset(end(result), -zp->z_gmtoff) != 0) {
+               result[0] = '\0';
+               return;
+       }
+       if (dstrp == NULL)
+               return;
+       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;
+               }
+       (void) strcat(result, ",");
+       if (stringrule(result, dstrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
+               result[0] = '\0';
+               return;
+       }
+       (void) strcat(result, ",");
+       if (stringrule(result, stdrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
+               result[0] = '\0';
+               return;
        }
 }
 
@@ -1637,8 +1974,17 @@ const int                        zonecount;
        register int                    startttisstd;
        register int                    startttisgmt;
        register int                    type;
-       char                            startbuf[BUFSIZ];
-
+       register char *                 startbuf;
+       register char *                 ab;
+       register char *                 envvar;
+       register int                    max_abbr_len;
+       register int                    max_envvar_len;
+
+       max_abbr_len = 2 + max_format_len + max_abbrvar_len;
+       max_envvar_len = 2 * max_abbr_len + 5 * 9;
+       startbuf = emalloc(max_abbr_len + 1);
+       ab = emalloc(max_abbr_len + 1);
+       envvar = emalloc(max_envvar_len + 1);
        INITIALIZE(untiltime);
        INITIALIZE(starttime);
        /*
@@ -1653,6 +1999,48 @@ const int                        zonecount;
        */
        startttisstd = FALSE;
        startttisgmt = FALSE;
+       min_year = max_year = EPOCH_YEAR;
+       if (leapseen) {
+               updateminmax(leapminyear);
+               updateminmax(leapmaxyear);
+       }
+       for (i = 0; i < zonecount; ++i) {
+               zp = &zpfirst[i];
+               updateminmax(zp->z_untilrule.r_loyear);
+               for (j = 0; j < zp->z_nrules; ++j) {
+                       rp = &zp->z_rules[j];
+                       if (rp->r_lowasnum)
+                               updateminmax(rp->r_loyear);
+                       if (rp->r_hiwasnum)
+                               updateminmax(rp->r_hiyear);
+               }
+       }
+       /*
+       ** Generate lots of data if a rule can't cover all future times.
+       */
+       stringzone(envvar, zpfirst, zonecount);
+       if (noise && envvar[0] == '\0') {
+               register char * wp;
+
+wp = ecpyalloc(_("no POSIX environment variable for zone"));
+               wp = ecatalloc(wp, " ");
+               wp = ecatalloc(wp, zpfirst->z_name); 
+               warning(wp);
+               ifree(wp);
+       }
+       if (envvar[0] == '\0') {
+               if (min_year >= INT_MIN + YEARSPERREPEAT)
+                       min_year -= YEARSPERREPEAT;
+               else    min_year = INT_MIN;
+               if (max_year <= INT_MAX - YEARSPERREPEAT)
+                       max_year += YEARSPERREPEAT;
+               else    max_year = INT_MAX;
+       }
+       /*
+       ** For the benefit of older systems, generate data through 2037.
+       */
+       if (max_year < 2037)
+               max_year = 2037;
        for (i = 0; i < zonecount; ++i) {
                /*
                ** A guess that may well be corrected later.
@@ -1670,7 +2058,7 @@ const int                 zonecount;
                if (zp->z_nrules == 0) {
                        stdoff = zp->z_stdoff;
                        doabbr(startbuf, zp->z_format,
-                               (char *) NULL, stdoff != 0);
+                               (char *) NULL, stdoff != 0, FALSE);
                        type = addtype(oadd(zp->z_gmtoff, stdoff),
                                startbuf, stdoff != 0, startttisstd,
                                startttisgmt);
@@ -1700,7 +2088,6 @@ const int                 zonecount;
                                register int    k;
                                register zic_t  jtime, ktime;
                                register long   offset;
-                               char            buf[BUFSIZ];
 
                                INITIALIZE(ktime);
                                if (useuntil) {
@@ -1756,24 +2143,27 @@ const int                       zonecount;
                                                        stdoff);
                                                doabbr(startbuf, zp->z_format,
                                                        rp->r_abbrvar,
-                                                       rp->r_stdoff != 0);
+                                                       rp->r_stdoff != 0,
+                                                       FALSE);
                                                continue;
                                        }
                                        if (*startbuf == '\0' &&
                                                startoff == oadd(zp->z_gmtoff,
-                                               stdoff))
+                                               stdoff)) {
                                                        doabbr(startbuf,
                                                                zp->z_format,
                                                                rp->r_abbrvar,
                                                                rp->r_stdoff !=
-                                                               0);
+                                                               0,
+                                                               FALSE);
+                                       }
                                }
                                eats(zp->z_filename, zp->z_linenum,
                                        rp->r_filename, rp->r_linenum);
-                               doabbr(buf, zp->z_format, rp->r_abbrvar,
-                                       rp->r_stdoff != 0);
+                               doabbr(ab, zp->z_format, rp->r_abbrvar,
+                                       rp->r_stdoff != 0, FALSE);
                                offset = oadd(zp->z_gmtoff, rp->r_stdoff);
-                               type = addtype(offset, buf, rp->r_stdoff != 0,
+                               type = addtype(offset, ab, rp->r_stdoff != 0,
                                        rp->r_todisstd, rp->r_todisgmt);
                                addtt(ktime, type);
                        }
@@ -1806,7 +2196,10 @@ error(_("can't determine time zone abbreviation to use just after until time"));
                                starttime = tadd(starttime, -gmtoff);
                }
        }
-       writezone(zpfirst->z_name);
+       writezone(zpfirst->z_name, envvar);
+       ifree(startbuf);
+       ifree(ab);
+       ifree(envvar);
 }
 
 static void
@@ -2185,8 +2578,6 @@ register const int                        wantedy;
 will not work with pre-2004 versions of zic"));
                }
        }
-       if (dayoff < 0 && !TYPE_SIGNED(zic_t))
-               return min_time;
        if (dayoff < min_time / SECSPERDAY)
                return min_time;
        if (dayoff > max_time / SECSPERDAY)