--- a/src/strftime.c
+++ b/src/strftime.c
@@ -1,10 +1,12 @@
-/* strftime - custom formatting of date and/or time
-   Copyright (C) 1989, 1991, 1992 Free Software Foundation, Inc.
+/* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
+
+   NOTE: The canonical source of this file is maintained with the GNU C
+   Library.  Bugs can be reported to bug-glibc@prep.ai.mit.edu.
 
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by the
+   Free Software Foundation; either version 2, or (at your option) any
+   later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -12,467 +14,878 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.  */
-
-/* Note: this version of strftime lacks locale support,
-   but it is standalone.
-
-   Performs `%' substitutions similar to those in printf.  Except
-   where noted, substituted fields have a fixed size; numeric fields are
-   padded if necessary.  Padding is with zeros by default; for fields
-   that display a single number, padding can be changed or inhibited by
-   following the `%' with one of the modifiers described below.  Unknown
-   field specifiers are copied as normal characters.  All other
-   characters are copied to the output without change.
-
-   Supports a superset of the ANSI C field specifiers.
-
-   Literal character fields:
-   %	%
-   n	newline
-   t	tab
-
-   Numeric modifiers (a nonstandard extension):
-   -	do not pad the field
-   _	pad the field with spaces
-
-   Time fields:
-   %H	hour (00..23)
-   %I	hour (01..12)
-   %k	hour ( 0..23)
-   %l	hour ( 1..12)
-   %M	minute (00..59)
-   %p	locale's AM or PM
-   %r	time, 12-hour (hh:mm:ss [AP]M)
-   %R	time, 24-hour (hh:mm)
-   %s	time in seconds since 00:00:00, Jan 1, 1970 (a nonstandard extension)
-   %S	second (00..61)
-   %T	time, 24-hour (hh:mm:ss)
-   %X	locale's time representation (%H:%M:%S)
-   %Z	time zone (EDT), or nothing if no time zone is determinable
-
-   Date fields:
-   %a	locale's abbreviated weekday name (Sun..Sat)
-   %A	locale's full weekday name, variable length (Sunday..Saturday)
-   %b	locale's abbreviated month name (Jan..Dec)
-   %B	locale's full month name, variable length (January..December)
-   %c	locale's date and time (Sat Nov 04 12:02:33 EST 1989)
-   %C	century (00..99)
-   %d	day of month (01..31)
-   %e	day of month ( 1..31)
-   %D	date (mm/dd/yy)
-   %h	same as %b
-   %j	day of year (001..366)
-   %m	month (01..12)
-   %U	week number of year with Sunday as first day of week (00..53)
-   %w	day of week (0..6)
-   %W	week number of year with Monday as first day of week (00..53)
-   %x	locale's date representation (mm/dd/yy)
-   %y	last two digits of year (00..99)
-   %Y	year (1970...)
-
-   David MacKenzie <djm@gnu.ai.mit.edu> */
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 
 #ifdef HAVE_CONFIG_H
-#include <config.h>
+# include <config.h>
+#endif
+
+#ifdef _LIBC
+# define HAVE_LIMITS_H 1
+# define HAVE_MBLEN 1
+# define HAVE_MBRLEN 1
+# define HAVE_STRUCT_ERA_ENTRY 1
+# define HAVE_TM_GMTOFF 1
+# define HAVE_TM_ZONE 1
+# define MULTIBYTE_IS_FORMAT_SAFE 1
+# define STDC_HEADERS 1
+# include <ansidecl.h>
+# include "../locale/localeinfo.h"
 #endif
 
-#include <stdio.h>
+#include <sys/types.h>		/* Some systems define `time_t' here.  */
 
-#ifdef HAVE_SYS_TYPES_H
-#include <sys/types.h>
+#ifdef TIME_WITH_SYS_TIME
+# include <sys/time.h>
+# include <time.h>
+#else
+# ifdef HAVE_SYS_TIME_H
+#  include <sys/time.h>
+# else
+#  include <time.h>
+# endif
+#endif
+
+#if HAVE_TZNAME
+extern char *tzname[];
 #endif
 
-#if defined(TIME_WITH_SYS_TIME)
-#include <sys/time.h>
-#include <time.h>
+/* Do multibyte processing if multibytes are supported, unless
+   multibyte sequences are safe in formats.  Multibyte sequences are
+   safe if they cannot contain byte sequences that look like format
+   conversion specifications.  The GNU C Library uses UTF8 multibyte
+   encoding, which is safe for formats, but strftime.c can be used
+   with other C libraries that use unsafe encodings.  */
+#define DO_MULTIBYTE (HAVE_MBLEN && ! MULTIBYTE_IS_FORMAT_SAFE)
+
+#if DO_MULTIBYTE
+# if HAVE_MBRLEN
+#  include <wchar.h>
+# else
+   /* Simulate mbrlen with mblen as best we can.  */
+#  define mbstate_t int
+#  define mbrlen(s, n, ps) mblen (s, n)
+#  define mbsinit(ps) (*(ps) == 0)
+# endif
+  static const mbstate_t mbstate_zero;
+#endif
+
+#if HAVE_LIMITS_H
+# include <limits.h>
+#endif
+
+#if STDC_HEADERS
+# include <stddef.h>
+# include <stdlib.h>
+# include <string.h>
 #else
-#if defined(HAVE_SYS_TIME_H)
-#include <sys/time.h>
+# define memcpy(d, s, n) bcopy (s, d, n)
+#endif
+
+#ifndef __P
+#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
+#define __P(args) args
 #else
-#include <time.h>
+#define __P(args) ()
+#endif  /* GCC.  */
+#endif  /* Not __P.  */
+
+#ifndef PTR
+#ifdef __STDC__
+#define PTR void *
+#else
+#define PTR char *
 #endif
 #endif
 
-#ifndef STDC_HEADERS
-time_t mktime ();
+#ifndef CHAR_BIT
+#define CHAR_BIT 8
 #endif
 
-#if defined(HAVE_TZNAME)
-extern char *tzname[2];
+#define TYPE_SIGNED(t) ((t) -1 < 0)
+
+/* Bound on length of the string representing an integer value of type t.
+   Subtract one for the sign bit if t is signed;
+   302 / 1000 is log10 (2) rounded up;
+   add one for integer division truncation;
+   add one more for a minus sign if t is signed.  */
+#define INT_STRLEN_BOUND(t) \
+  ((sizeof (t) * CHAR_BIT - TYPE_SIGNED (t)) * 302 / 100 + 1 + TYPE_SIGNED (t))
+
+#define TM_YEAR_BASE 1900
+
+#ifndef __isleap
+/* Nonzero if YEAR is a leap year (every 4 years,
+   except every 100th isn't, and every 400th is).  */
+#define __isleap(year)	\
+  ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
 #endif
 
-/* Types of padding for numbers in date and time. */
-enum padding
-{
-  none, blank, zero
-};
 
-static char const* const days[] =
+#ifdef _LIBC
+# define gmtime_r __gmtime_r
+# define localtime_r __localtime_r
+#else
+# if ! HAVE_LOCALTIME_R
+#  if ! HAVE_TM_GMTOFF
+/* Approximate gmtime_r as best we can in its absence.  */
+#define gmtime_r my_gmtime_r
+static struct tm *gmtime_r __P ((const time_t *, struct tm *));
+static struct tm *
+gmtime_r (t, tp)
+     const time_t *t;
+     struct tm *tp;
 {
-  "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
-};
+  struct tm *l = gmtime (t);
+  if (! l)
+    return 0;
+  *tp = *l;
+  return tp;
+}
+#  endif /* ! HAVE_TM_GMTOFF */
 
-static char const * const months[] =
+/* Approximate localtime_r as best we can in its absence.  */
+#define localtime_r my_localtime_r
+static struct tm *localtime_r __P ((const time_t *, struct tm *));
+static struct tm *
+localtime_r (t, tp)
+     const time_t *t;
+     struct tm *tp;
 {
-  "January", "February", "March", "April", "May", "June",
-  "July", "August", "September", "October", "November", "December"
-};
+  struct tm *l = localtime (t);
+  if (! l)
+    return 0;
+  *tp = *l;
+  return tp;
+}
+# endif /* ! HAVE_LOCALTIME_R */
+#endif /* ! defined (_LIBC) */
 
-/* Add character C to STRING and increment LENGTH,
-   unless LENGTH would exceed MAX. */
 
-#define add_char(c)							\
-  do									\
-    {									\
-      if (length + 1 <= max)						\
-	string[length++] = (c);						\
-    }									\
-  while (0)
+#define	add(n, f)							      \
+  do									      \
+    {									      \
+      i += (n);								      \
+      if (i >= maxsize)							      \
+	return 0;							      \
+      else								      \
+	if (p)								      \
+	  {								      \
+	    f;								      \
+	    p += (n);							      \
+	  }								      \
+    } while (0)
+#define	cpy(n, s)	add ((n), memcpy((PTR) p, (PTR) (s), (n)))
 
-/* Add a 2 digit number to STRING, padding if specified.
-   Return the number of characters added, up to MAX. */
-
+#if ! HAVE_TM_GMTOFF
+/* Yield the difference between *A and *B,
+   measured in seconds, ignoring leap seconds.  */
+static int tm_diff __P ((const struct tm *, const struct tm *));
 static int
-add_num2 (string, num, max, pad)
-     char *string;
-     int num;
-     int max;
-     enum padding pad;
+tm_diff (a, b)
+     const struct tm *a;
+     const struct tm *b;
 {
-  int top = num / 10;
-  int length = 0;
+  /* Compute intervening leap days correctly even if year is negative.
+     Take care to avoid int overflow in leap day calculations,
+     but it's OK to assume that A and B are close to each other.  */
+  int a4 = (a->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (a->tm_year & 3);
+  int b4 = (b->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (b->tm_year & 3);
+  int a100 = a4 / 25 - (a4 % 25 < 0);
+  int b100 = b4 / 25 - (b4 % 25 < 0);
+  int a400 = a100 >> 2;
+  int b400 = b100 >> 2;
+  int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
+  int years = a->tm_year - b->tm_year;
+  int days = (365 * years + intervening_leap_days
+	      + (a->tm_yday - b->tm_yday));
+  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+	  + (a->tm_sec - b->tm_sec));
+}
+#endif /* ! HAVE_TM_GMTOFF */
+
+
 
-  if (top == 0 && pad == blank)
-    add_char (' ');
-  else if (top != 0 || pad == zero)
-    add_char (top + '0');
-  add_char (num % 10 + '0');
-  return length;
+/* The number of days from the first day of the first ISO week of this
+   year to the year day YDAY with week day WDAY.  ISO weeks start on
+   Monday; the first ISO week has the year's first Thursday.  YDAY may
+   be as small as YDAY_MINIMUM.  */
+#define ISO_WEEK_START_WDAY 1 /* Monday */
+#define ISO_WEEK1_WDAY 4 /* Thursday */
+#define YDAY_MINIMUM (-366)
+static int iso_week_days __P ((int, int));
+#ifdef __GNUC__
+inline
+#endif
+static int
+iso_week_days (yday, wday)
+     int yday;
+     int wday;
+{
+  /* Add enough to the first operand of % to make it nonnegative.  */
+  int big_enough_multiple_of_7 = (-YDAY_MINIMUM / 7 + 2) * 7;
+  return (yday
+	  - (yday - wday + ISO_WEEK1_WDAY + big_enough_multiple_of_7) % 7
+	  + ISO_WEEK1_WDAY - ISO_WEEK_START_WDAY);
 }
 
-/* Add a 3 digit number to STRING, padding if specified.
-   Return the number of characters added, up to MAX. */
 
-static int
-add_num3 (string, num, max, pad)
-     char *string;
-     int num;
-     int max;
-     enum padding pad;
-{
-  int top = num / 100;
-  int mid = (num - top * 100) / 10;
-  int length = 0;
-
-  if (top == 0 && pad == blank)
-    add_char (' ');
-  else if (top != 0 || pad == zero)
-    add_char (top + '0');
-  if (mid == 0 && top == 0 && pad == blank)
-    add_char (' ');
-  else if (mid != 0 || top != 0 || pad == zero)
-    add_char (mid + '0');
-  add_char (num % 10 + '0');
-  return length;
-}
+#ifndef _NL_CURRENT
+static char const weekday_name[][10] =
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday",
+    "Thursday", "Friday", "Saturday"
+  };
+static char const month_name[][10] =
+  {
+    "January", "February", "March", "April", "May", "June",
+    "July", "August", "September", "October", "November", "December"
+  };
+#endif
 
-/* Like strncpy except return the number of characters copied. */
-
-static int
-add_str (to, from, max)
-     char *to;
-     const char *from;
-     int max;
+/* Write information from TP into S according to the format
+   string FORMAT, writing no more that MAXSIZE characters
+   (including the terminating '\0') and returning number of
+   characters written.  If S is NULL, nothing will be written
+   anywhere, so to determine how many characters would be
+   written, use NULL for S and (size_t) UINT_MAX for MAXSIZE.  */
+size_t
+strftime (s, maxsize, format, tp)
+      char *s;
+      size_t maxsize;
+      const char *format;
+      register const struct tm *tp;
 {
-  int i;
+  int hour12 = tp->tm_hour;
+#ifdef _NL_CURRENT
+  const char *const a_wkday = _NL_CURRENT (LC_TIME, ABDAY_1 + tp->tm_wday);
+  const char *const f_wkday = _NL_CURRENT (LC_TIME, DAY_1 + tp->tm_wday);
+  const char *const a_month = _NL_CURRENT (LC_TIME, ABMON_1 + tp->tm_mon);
+  const char *const f_month = _NL_CURRENT (LC_TIME, MON_1 + tp->tm_mon);
+  const char *const ampm = _NL_CURRENT (LC_TIME,
+					hour12 > 11 ? PM_STR : AM_STR);
+  size_t aw_len = strlen (a_wkday);
+  size_t am_len = strlen (a_month);
+  size_t ap_len = strlen (ampm);
+#else
+  const char *const f_wkday = weekday_name[tp->tm_wday];
+  const char *const f_month = month_name[tp->tm_mon];
+  const char *const a_wkday = f_wkday;
+  const char *const a_month = f_month;
+  const char *const ampm = "AMPM" + 2 * (hour12 > 11);
+  size_t aw_len = 3;
+  size_t am_len = 3;
+  size_t ap_len = 2;
+#endif
+  size_t wkday_len = strlen (f_wkday);
+  size_t month_len = strlen (f_month);
+  const char *zone;
+  size_t zonelen;
+  register size_t i = 0;
+  register char *p = s;
+  register const char *f;
 
-  for (i = 0; from[i] && i <= max; ++i)
-    to[i] = from[i];
-  return i;
-}
+  zone = 0;
+#if HAVE_TM_ZONE
+  zone = (const char *) tp->tm_zone;
+#endif
+#if HAVE_TZNAME
+  if (!(zone && *zone) && tp->tm_isdst >= 0)
+    zone = tzname[tp->tm_isdst];
+#endif
+  if (! zone)
+    zone = "";		/* POSIX.2 requires the empty string here.  */
+
+  zonelen = strlen (zone);
+
+  if (hour12 > 12)
+    hour12 -= 12;
+  else
+    if (hour12 == 0) hour12 = 12;
 
-static int
-add_num_time_t (string, max, num)
-     char *string;
-     int max;
-     time_t num;
-{
-  /* This buffer is large enough to hold the character representation
-     (including the trailing NUL) of any unsigned decimal quantity
-     whose binary representation fits in 128 bits.  */
-  char buf[40];
-  int length;
+  for (f = format; *f != '\0'; ++f)
+    {
+      int pad;			/* Padding for number ('-', '_', or 0).  */
+      int modifier;		/* Field modifier ('E', 'O', or 0).  */
+      int digits;		/* Max digits for numeric format.  */
+      int number_value; 	/* Numeric value to be printed.  */
+      int negative_number;	/* 1 if the number is negative.  */
+      const char *subfmt;
+      char *bufp;
+      char buf[1 + (sizeof (int) < sizeof (time_t)
+		    ? INT_STRLEN_BOUND (time_t)
+		    : INT_STRLEN_BOUND (int))];
+
+#if DO_MULTIBYTE
+
+       switch (*f)
+	{
+	case '%':
+	  break;
 
-  if (sizeof (num) > 16)
-    abort ();
-  sprintf (buf, "%lu", (unsigned long) num);
-  length = add_str (string, buf, max);
-  return length;
-}
+	case '\a': case '\b': case '\t': case '\n':
+	case '\v': case '\f': case '\r':
+	case ' ': case '!': case '"': case '#': case '&': case'\'':
+	case '(': case ')': case '*': case '+': case ',': case '-':
+	case '.': case '/': case '0': case '1': case '2': case '3':
+	case '4': case '5': case '6': case '7': case '8': case '9':
+	case ':': case ';': case '<': case '=': case '>': case '?':
+	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 '[': case'\\': case ']': case '^':
+	case '_': 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 '{': case '|': case '}':
+	case '~':
+	  /* The C Standard requires these 98 characters (plus '%') to
+	     be in the basic execution character set.  None of these
+	     characters can start a multibyte sequence, so they need
+	     not be analyzed further.  */
+	  add (1, *p = *f);
+	  continue;
 
-/* Return the week in the year of the time in TM, with the weeks
-   starting on Sundays. */
+	default:
+	  /* Copy this multibyte sequence until we reach its end, find
+	     an error, or come back to the initial shift state.  */
+	  {
+	    mbstate_t mbstate = mbstate_zero;
+	    size_t len = 0;
 
-static int
-sun_week (tm)
-     struct tm *tm;
-{
-  int dl;
+	    do
+	      {
+		size_t bytes = mbrlen (f + len, (size_t) -1, &mbstate);
+
+		if (bytes == 0)
+		  break;
+
+		if (bytes == (size_t) -2 || bytes == (size_t) -1)
+		  {
+		    len++;
+		    break;
+		  }
+
+		len += bytes;
+	      }
+	    while (! mbsinit (&mbstate));
 
-  /* Set `dl' to the day in the year of the last day of the week previous
-     to the one containing the day specified in TM.  If the day specified
-     in TM is in the first week of the year, `dl' will be negative or 0.
-     Otherwise, calculate the number of complete weeks before our week
-     (dl / 7) and add any partial week at the start of the year (dl % 7). */
-  dl = tm->tm_yday - tm->tm_wday;
-  return dl <= 0 ? 0 : dl / 7 + (dl % 7 != 0);
-}
+	    cpy (len, f);
+	    continue;
+	  }
+	}
+
+#else /* ! DO_MULTIBYTE */
+
+      /* Either multibyte encodings are not supported, or they are
+	 safe for formats, so any non-'%' byte can be copied through.  */
+      if (*f != '%')
+	{
+	  add (1, *p = *f);
+	  continue;
+	}
+
+#endif /* ! DO_MULTIBYTE */
 
-/* Return the week in the year of the time in TM, with the weeks
-   starting on Mondays. */
+      /* Check for flags that can modify a number format.  */
+      ++f;
+      switch (*f)
+	{
+	case '_':
+	case '-':
+	  pad = *f++;
+	  break;
+
+	default:
+	  pad = 0;
+	  break;
+	}
 
-static int
-mon_week (tm)
-     struct tm *tm;
-{
-  int dl, wday;
+      /* Check for modifiers.  */
+      switch (*f)
+	{
+	case 'E':
+	case 'O':
+	  modifier = *f++;
+	  break;
+
+	default:
+	  modifier = 0;
+	  break;
+	}
+
+      /* Now do the specified format.  */
+      switch (*f)
+	{
+#define DO_NUMBER(d, v) \
+	  digits = d; number_value = v; goto do_number
+#define DO_NUMBER_SPACEPAD(d, v) \
+	  digits = d; number_value = v; goto do_number_spacepad
 
-  if (tm->tm_wday == 0)
-    wday = 6;
-  else
-    wday = tm->tm_wday - 1;
-  dl = tm->tm_yday - wday;
-  return dl <= 0 ? 0 : dl / 7 + (dl % 7 != 0);
-}
+	case '%':
+	  if (modifier != 0)
+	    goto bad_format;
+	  add (1, *p = *f);
+	  break;
+
+	case 'a':
+	  if (modifier != 0)
+	    goto bad_format;
+	  cpy (aw_len, a_wkday);
+	  break;
+
+	case 'A':
+	  if (modifier != 0)
+	    goto bad_format;
+	  cpy (wkday_len, f_wkday);
+	  break;
 
-#if !defined(HAVE_TM_ZONE) && !defined(HAVE_TZNAME)
-char *
-zone_name (tp)
-     struct tm *tp;
-{
-  char *timezone ();
-  struct timeval tv;
-  struct timezone tz;
+	case 'b':
+	case 'h':		/* POSIX.2 extension.  */
+	  if (modifier != 0)
+	    goto bad_format;
+	  cpy (am_len, a_month);
+	  break;
 
-  gettimeofday (&tv, &tz);
-  return timezone (tz.tz_minuteswest, tp->tm_isdst);
-}
+	case 'B':
+	  if (modifier != 0)
+	    goto bad_format;
+	  cpy (month_len, f_month);
+	  break;
+
+	case 'c':
+	  if (modifier == 'O')
+	    goto bad_format;
+#ifdef _NL_CURRENT
+	  if (! (modifier == 'E'
+		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_D_T_FMT)) != '\0'))
+	    subfmt = _NL_CURRENT (LC_TIME, D_T_FMT);
+#else
+	  subfmt = "%a %b %e %H:%M:%S %Y";
 #endif
 
-/* Format the time given in TM according to FORMAT, and put the
-   results in STRING.
-   Return the number of characters (not including terminating null)
-   that were put into STRING, or 0 if the length would have
-   exceeded MAX. */
+	subformat:
+	  {
+	    size_t len = strftime (p, maxsize - i, subfmt, tp);
+	    if (len == 0 && *subfmt)
+	      return 0;
+	    add (len, ;);
+	  }
+	  break;
 
-size_t
-strftime (string, max, format, tm)
-     char *string;
-     size_t max;
-     const char *format;
-     const struct tm *tm;
-{
-  enum padding pad;		/* Type of padding to apply. */
-  size_t length = 0;		/* Characters put in STRING so far. */
+	case 'C':		/* POSIX.2 extension.  */
+	  if (modifier == 'O')
+	    goto bad_format;
+#if HAVE_STRUCT_ERA_ENTRY
+	  if (modifier == 'E')
+	    {
+	      struct era_entry *era = _nl_get_era_entry (tp);
+	      if (era)
+		{
+		  size_t len = strlen (era->name_fmt);
+		  cpy (len, era->name_fmt);
+		  break;
+		}
+	    }
+#endif
+	  {
+	    int year = tp->tm_year + TM_YEAR_BASE;
+	    DO_NUMBER (1, year / 100 - (year % 100 < 0));
+	  }
+
+	case 'x':
+	  if (modifier == 'O')
+	    goto bad_format;
+#ifdef _NL_CURRENT
+	  if (! (modifier == 'E'
+		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_D_FMT)) != '\0'))
+	    subfmt = _NL_CURRENT (LC_TIME, D_FMT);
+	  goto subformat;
+#endif
+	  /* Fall through.  */
+	case 'D':		/* POSIX.2 extension.  */
+	  if (modifier != 0)
+	    goto bad_format;
+	  subfmt = "%m/%d/%y";
+	  goto subformat;
+
+	case 'd':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, tp->tm_mday);
 
-  for (; *format && length < max; ++format)
-    {
-      if (*format != '%')
-	add_char (*format);
-      else
-	{
-	  ++format;
-	  /* Modifiers: */
-	  if (*format == '-')
+	case 'e':		/* POSIX.2 extension.  */
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER_SPACEPAD (2, tp->tm_mday);
+
+	  /* All numeric formats set DIGITS and NUMBER_VALUE and then
+	     jump to one of these two labels.  */
+
+	do_number_spacepad:
+	  /* Force `_' flag.  */
+	  pad = '_';
+
+	do_number:
+	  /* Format the number according to the MODIFIER flag.  */
+
+#ifdef _NL_CURRENT
+	  if (modifier == 'O' && 0 <= number_value)
 	    {
-	      pad = none;
-	      ++format;
+	      /* Get the locale specific alternate representation of
+		 the number NUMBER_VALUE.  If none exist NULL is returned.  */
+	      const char *cp = _nl_get_alt_digit (number_value);
+
+	      if (cp != NULL)
+		{
+		  size_t digitlen = strlen (cp);
+		  if (digitlen != 0)
+		    {
+		      cpy (digitlen, cp);
+		      break;
+		    }
+		}
 	    }
-	  else if (*format == '_')
-	    {
-	      pad = blank;
-	      ++format;
-	    }
-	  else
-	    pad = zero;
+#endif
+	  {
+	    unsigned int u = number_value;
+
+	    bufp = buf + sizeof (buf);
+	    negative_number = number_value < 0;
+
+	    if (negative_number)
+	      u = -u;
 
-	  switch (*format)
+	    do
+	      *--bufp = u % 10 + '0';
+	    while ((u /= 10) != 0);
+  	  }
+
+	do_number_sign_and_padding:
+	  if (negative_number)
+	    *--bufp = '-';
+
+	  if (pad != '-')
 	    {
-	      /* Literal character fields: */
-	    case 0:
-	    case '%':
-	      add_char ('%');
-	      break;
-	    case 'n':
-	      add_char ('\n');
-	      break;
-	    case 't':
-	      add_char ('\t');
-	      break;
-	    default:
-	      add_char (*format);
-	      break;
+	      int padding = digits - (buf + sizeof (buf) - bufp);
+
+	      if (pad == '_')
+		{
+		  while (0 < padding--)
+		    *--bufp = ' ';
+		}
+	      else
+		{
+		  bufp += negative_number;
+		  while (0 < padding--)
+		    *--bufp = '0';
+		  if (negative_number)
+		    *--bufp = '-';
+		}
+	    }
+
+	  cpy (buf + sizeof (buf) - bufp, bufp);
+	  break;
+
+
+	case 'H':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, tp->tm_hour);
+
+	case 'I':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, hour12);
+
+	case 'k':		/* GNU extension.  */
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER_SPACEPAD (2, tp->tm_hour);
+
+	case 'l':		/* GNU extension.  */
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER_SPACEPAD (2, hour12);
+
+	case 'j':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (3, 1 + tp->tm_yday);
+
+	case 'M':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, tp->tm_min);
+
+	case 'm':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, tp->tm_mon + 1);
 
-	      /* Time fields: */
-	    case 'H':
-	    case 'k':
-	      length +=
-		add_num2 (&string[length], tm->tm_hour, max - length,
-			  *format == 'H' ? pad : blank);
-	      break;
-	    case 'I':
-	    case 'l':
+	case 'n':		/* POSIX.2 extension.  */
+	  add (1, *p = '\n');
+	  break;
+
+	case 'p':
+	  cpy (ap_len, ampm);
+	  break;
+
+	case 'R':		/* GNU extension.  */
+	  subfmt = "%H:%M";
+	  goto subformat;
+
+	case 'r':		/* POSIX.2 extension.  */
+#ifdef _NL_CURRENT
+	  if (*(subfmt = _NL_CURRENT (LC_TIME, T_FMT_AMPM)) == '\0')
+#endif
+	    subfmt = "%I:%M:%S %p";
+	  goto subformat;
+
+	case 'S':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, tp->tm_sec);
+
+	case 's':		/* GNU extension.  */
+  	  {
+	    struct tm ltm;
+	    time_t t;
+
+	    ltm = *tp;
+	    t = mktime (&ltm);
+
+	    /* Generate string value for T using time_t arithmetic;
+	       this works even if sizeof (long) < sizeof (time_t).  */
+
+	    bufp = buf + sizeof (buf);
+	    negative_number = t < 0;
+
+	    do
 	      {
-		int hour12;
+		int d = t % 10;
+		t /= 10;
+
+		if (negative_number)
+		  {
+		    d = -d;
+
+		    /* Adjust if division truncates to minus infinity.  */
+		    if (0 < -1 % 10 && d < 0)
+		      {
+			t++;
+			d += 10;
+		      }
+		  }
+
+		*--bufp = d + '0';
+	      }
+	    while (t != 0);
+
+	    digits = 1;
+	    goto do_number_sign_and_padding;
+	  }
 
-		if (tm->tm_hour == 0)
-		  hour12 = 12;
-		else if (tm->tm_hour > 12)
-		  hour12 = tm->tm_hour - 12;
-		else
-		  hour12 = tm->tm_hour;
-		length +=
-		  add_num2 (&string[length], hour12, max - length,
-			    *format == 'I' ? pad : blank);
+	case 'X':
+	  if (modifier == 'O')
+	    goto bad_format;
+#ifdef _NL_CURRENT
+	  if (! (modifier == 'E'
+		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_T_FMT)) != '\0'))
+	    subfmt = _NL_CURRENT (LC_TIME, T_FMT);
+	  goto subformat;
+#endif
+	  /* Fall through.  */
+	case 'T':		/* POSIX.2 extension.  */
+	  subfmt = "%H:%M:%S";
+	  goto subformat;
+
+	case 't':		/* POSIX.2 extension.  */
+	  add (1, *p = '\t');
+	  break;
+
+	case 'u':		/* POSIX.2 extension.  */
+	  DO_NUMBER (1, (tp->tm_wday - 1 + 7) % 7 + 1);
+
+	case 'U':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, (tp->tm_yday - tp->tm_wday + 7) / 7);
+
+	case 'V':
+	case 'g':		/* GNU extension.  */
+	case 'G':		/* GNU extension.  */
+	  if (modifier == 'E')
+	    goto bad_format;
+	  {
+	    int year = tp->tm_year + TM_YEAR_BASE;
+	    int days = iso_week_days (tp->tm_yday, tp->tm_wday);
+
+	    if (days < 0)
+	      {
+		/* This ISO week belongs to the previous year.  */
+		year--;
+		days = iso_week_days (tp->tm_yday + (365 + __isleap (year)),
+				      tp->tm_wday);
+	      }
+	    else
+	      {
+		int d = iso_week_days (tp->tm_yday - (365 + __isleap (year)),
+				       tp->tm_wday);
+		if (0 <= d)
+		  {
+		    /* This ISO week belongs to the next year.  */
+		    year++;
+		    days = d;
+		  }
+	      }
+
+	    switch (*f)
+	      {
+	      case 'g':
+		DO_NUMBER (2, (year % 100 + 100) % 100);
+
+	      case 'G':
+		DO_NUMBER (1, year);
+
+	      default:
+		DO_NUMBER (2, days / 7 + 1);
 	      }
-	      break;
-	    case 'M':
-	      length +=
-		add_num2 (&string[length], tm->tm_min, max - length, pad);
-	      break;
-	    case 'p':
-	      if (tm->tm_hour < 12)
-		add_char ('A');
-	      else
-		add_char ('P');
-	      add_char ('M');
-	      break;
-	    case 'r':
-	      length +=
-		strftime (&string[length], max - length, "%I:%M:%S %p", tm);
-	      break;
-	    case 'R':
-	      length +=
-		strftime (&string[length], max - length, "%H:%M", tm);
-	      break;
+	  }
+
+	case 'W':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (2, (tp->tm_yday - (tp->tm_wday - 1 + 7) % 7 + 7) / 7);
+
+	case 'w':
+	  if (modifier == 'E')
+	    goto bad_format;
+
+	  DO_NUMBER (1, tp->tm_wday);
+
+	case 'Y':
+#if HAVE_STRUCT_ERA_ENTRY
+	  if (modifier == 'E')
+	    {
+	      struct era_entry *era = _nl_get_era_entry (tp);
+	      if (era)
+		{
+		  subfmt = strchr (era->name_fmt, '\0') + 1;
+		  goto subformat;
+		}
+	    }
+#endif
+	  if (modifier == 'O')
+	    goto bad_format;
+	  else
+	    DO_NUMBER (1, tp->tm_year + TM_YEAR_BASE);
 
-	    case 's':
+	case 'y':
+#if HAVE_STRUCT_ERA_ENTRY
+	  if (modifier == 'E')
+	    {
+	      struct era_entry *era = _nl_get_era_entry (tp);
+	      if (era)
+		{
+		  int delta = tp->tm_year - era->start_date[0];
+		  DO_NUMBER (1, (era->offset
+				 + (era->direction == '-' ? -delta : delta)));
+		}
+	    }
+#endif
+	  DO_NUMBER (2, (tp->tm_year % 100 + 100) % 100);
+
+	case 'Z':
+	  cpy (zonelen, zone);
+	  break;
+
+	case 'z':		/* GNU extension.  */
+	  if (tp->tm_isdst < 0)
+	    break;
+
+	  {
+	    int diff;
+#if HAVE_TM_GMTOFF
+	    diff = tp->tm_gmtoff;
+#else
+	    struct tm gtm;
+	    struct tm ltm;
+	    time_t lt;
+
+	    ltm = *tp;
+	    lt = mktime (&ltm);
+
+	    if (lt == (time_t) -1)
 	      {
-		struct tm writable_tm;
-		writable_tm = *tm;
-		length += add_num_time_t (&string[length], max - length,
-					  mktime (&writable_tm));
+		/* mktime returns -1 for errors, but -1 is also a
+		   valid time_t value.  Check whether an error really
+		   occurred.  */
+		struct tm tm;
+		localtime_r (&lt, &tm);
+
+		if ((ltm.tm_sec ^ tm.tm_sec)
+		    | (ltm.tm_min ^ tm.tm_min)
+		    | (ltm.tm_hour ^ tm.tm_hour)
+		    | (ltm.tm_mday ^ tm.tm_mday)
+		    | (ltm.tm_mon ^ tm.tm_mon)
+		    | (ltm.tm_year ^ tm.tm_year))
+		  break;
 	      }
+
+	    if (! gmtime_r (&lt, &gtm))
 	      break;
 
-	    case 'S':
-	      length +=
-		add_num2 (&string[length], tm->tm_sec, max - length, pad);
-	      break;
-	    case 'T':
-	      length +=
-		strftime (&string[length], max - length, "%H:%M:%S", tm);
-	      break;
-	    case 'X':
-	      length +=
-		strftime (&string[length], max - length, "%H:%M:%S", tm);
-	      break;
-	    case 'Z':
-#ifdef HAVE_TM_ZONE
-	      length += add_str (&string[length], tm->tm_zone, max - length);
-#else
-#ifdef HAVE_TZNAME
-	      if (tm->tm_isdst && tzname[1] && *tzname[1])
-		length += add_str (&string[length], tzname[1], max - length);
-	      else
-		length += add_str (&string[length], tzname[0], max - length);
-#else
-	      length += add_str (&string[length], zone_name (tm), max - length);
+	    diff = tm_diff (&ltm, &gtm);
 #endif
-#endif
-	      break;
+
+	    if (diff < 0)
+	      {
+		add (1, *p = '-');
+		diff = -diff;
+	      }
+	    else
+	      add (1, *p = '+');
+
+	    diff /= 60;
+	    DO_NUMBER (4, (diff / 60) * 100 + diff % 60);
+	  }
 
-	      /* Date fields: */
-	    case 'a':
-	      add_char (days[tm->tm_wday][0]);
-	      add_char (days[tm->tm_wday][1]);
-	      add_char (days[tm->tm_wday][2]);
-	      break;
-	    case 'A':
-	      length +=
-		add_str (&string[length], days[tm->tm_wday], max - length);
-	      break;
-	    case 'b':
-	    case 'h':
-	      add_char (months[tm->tm_mon][0]);
-	      add_char (months[tm->tm_mon][1]);
-	      add_char (months[tm->tm_mon][2]);
-	      break;
-	    case 'B':
-	      length +=
-		add_str (&string[length], months[tm->tm_mon], max - length);
-	      break;
-	    case 'c':
-	      length +=
-		strftime (&string[length], max - length,
-			  "%a %b %d %H:%M:%S %Z %Y", tm);
-	      break;
-	    case 'C':
-	      length +=
-		add_num2 (&string[length], (tm->tm_year + 1900) / 100,
-			  max - length, pad);
-	      break;
-	    case 'd':
-	      length +=
-		add_num2 (&string[length], tm->tm_mday, max - length, pad);
-	      break;
-	    case 'e':
-	      length +=
-		add_num2 (&string[length], tm->tm_mday, max - length, blank);
-	      break;
-	    case 'D':
-	      length +=
-		strftime (&string[length], max - length, "%m/%d/%y", tm);
-	      break;
-	    case 'j':
-	      length +=
-		add_num3 (&string[length], tm->tm_yday + 1, max - length, pad);
-	      break;
-	    case 'm':
-	      length +=
-		add_num2 (&string[length], tm->tm_mon + 1, max - length, pad);
-	      break;
-	    case 'U':
-	      length +=
-		add_num2 (&string[length], sun_week (tm), max - length, pad);
-	      break;
-	    case 'w':
-	      add_char (tm->tm_wday + '0');
-	      break;
-	    case 'W':
-	      length +=
-		add_num2 (&string[length], mon_week (tm), max - length, pad);
-	      break;
-	    case 'x':
-	      length +=
-		strftime (&string[length], max - length, "%m/%d/%y", tm);
-	      break;
-	    case 'y':
-	      length +=
-		add_num2 (&string[length], tm->tm_year % 100,
-			  max - length, pad);
-	      break;
-	    case 'Y':
-	      add_char ((tm->tm_year + 1900) / 1000 + '0');
-	      length +=
-		add_num3 (&string[length],
-			  (1900 + tm->tm_year) % 1000, max - length, zero);
-	      break;
-	    }
+	case '\0':		/* GNU extension: % at end of format.  */
+	    --f;
+	    /* Fall through.  */
+	default:
+	  /* Unknown format; output the format, including the '%',
+	     since this is most likely the right thing to do if a
+	     multibyte string has been misparsed.  */
+	bad_format:
+	  {
+	    int flen;
+	    for (flen = 1; f[1 - flen] != '%'; flen++)
+	      continue;
+	    cpy (flen, &f[1 - flen]);
+	  }
+	  break;
 	}
     }
-  add_char (0);
-  return length - 1;
+
+  if (p)
+    *p = '\0';
+  return i;
 }