lib/nstrftime.c

   1 /* Copyright (C) 1991-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #ifdef _LIBC
  19 # define USE_IN_EXTENDED_LOCALE_MODEL 1
  20 # define HAVE_STRUCT_ERA_ENTRY 1
  21 # define HAVE_TM_GMTOFF 1
  22 # define HAVE_TM_ZONE 1
  23 # define HAVE_TZNAME 1
  24 # include "../locale/localeinfo.h"
  25 #else
  26 # include <config.h>
  27 # if FPRINTFTIME
  28 #  include "fprintftime.h"
  29 # else
  30 #  include "strftime.h"
  31 # endif
  32 # include "time-internal.h"
  33 #endif
  34
  35 #include <ctype.h>
  36 #include <errno.h>
  37 #include <time.h>
  38
  39 #if HAVE_TZNAME && !HAVE_DECL_TZNAME
  40 extern char *tzname[];
  41 #endif
  42
  43 /* Do multibyte processing if multibyte encodings are supported, unless
  44    multibyte sequences are safe in formats.  Multibyte sequences are
  45    safe if they cannot contain byte sequences that look like format
  46    conversion specifications.  The multibyte encodings used by the
  47    C library on the various platforms (UTF-8, GB2312, GBK, CP936,
  48    GB18030, EUC-TW, BIG5, BIG5-HKSCS, CP950, EUC-JP, EUC-KR, CP949,
  49    SHIFT_JIS, CP932, JOHAB) are safe for formats, because the byte '%'
  50    cannot occur in a multibyte character except in the first byte.
  51
  52    The DEC-HANYU encoding used on OSF/1 is not safe for formats, but
  53    this encoding has never been seen in real-life use, so we ignore
  54    it.  */
  55 #if !(defined __osf__ && 0)
  56 # define MULTIBYTE_IS_FORMAT_SAFE 1
  57 #endif
  58 #define DO_MULTIBYTE (! MULTIBYTE_IS_FORMAT_SAFE)
  59
  60 #if DO_MULTIBYTE
  61 # include <wchar.h>
  62   static const mbstate_t mbstate_zero;
  63 #endif
  64
  65 #include <limits.h>
  66 #include <stddef.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <stdbool.h>
  70
  71 #include "attribute.h"
  72 #include <intprops.h>
  73
  74 #ifdef COMPILE_WIDE
  75 # include <endian.h>
  76 # define CHAR_T wchar_t
  77 # define UCHAR_T unsigned int
  78 # define L_(Str) L##Str
  79 # define NLW(Sym) _NL_W##Sym
  80
  81 # define MEMCPY(d, s, n) __wmemcpy (d, s, n)
  82 # define STRLEN(s) __wcslen (s)
  83
  84 #else
  85 # define CHAR_T char
  86 # define UCHAR_T unsigned char
  87 # define L_(Str) Str
  88 # define NLW(Sym) Sym
  89 # define ABALTMON_1 _NL_ABALTMON_1
  90
  91 # define MEMCPY(d, s, n) memcpy (d, s, n)
  92 # define STRLEN(s) strlen (s)
  93
  94 #endif
  95
  96 /* Shift A right by B bits portably, by dividing A by 2**B and
  97    truncating towards minus infinity.  A and B should be free of side
  98    effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
  99    INT_BITS is the number of useful bits in an int.  GNU code can
 100    assume that INT_BITS is at least 32.
 101
 102    ISO C99 says that A >> B is implementation-defined if A < 0.  Some
 103    implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
 104    right in the usual way when A < 0, so SHR falls back on division if
 105    ordinary A >> B doesn't seem to be the usual signed shift.  */
 106 #define SHR(a, b)       \
 107   (-1 >> 1 == -1        \
 108    ? (a) >> (b)         \
 109    : ((a) + ((a) < 0)) / (1 << (b)) - ((a) < 0))
 110
 111 #define TM_YEAR_BASE 1900
 112
 113 #ifndef __isleap
 114 /* Nonzero if YEAR is a leap year (every 4 years,
 115    except every 100th isn't, and every 400th is).  */
 116 # define __isleap(year) \
 117   ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
 118 #endif
 119
 120
 121 #ifdef _LIBC
 122 # define mktime_z(tz, tm) mktime (tm)
 123 # define tzname __tzname
 124 # define tzset __tzset
 125 #endif
 126
 127 #ifndef FPRINTFTIME
 128 # define FPRINTFTIME 0
 129 #endif
 130
 131 #if FPRINTFTIME
 132 # define STREAM_OR_CHAR_T FILE
 133 # define STRFTIME_ARG(x) /* empty */
 134 #else
 135 # define STREAM_OR_CHAR_T CHAR_T
 136 # define STRFTIME_ARG(x) x,
 137 #endif
 138
 139 #if FPRINTFTIME
 140 # define memset_byte(P, Len, Byte) \
 141   do { size_t _i; for (_i = 0; _i < Len; _i++) fputc (Byte, P); } while (0)
 142 # define memset_space(P, Len) memset_byte (P, Len, ' ')
 143 # define memset_zero(P, Len) memset_byte (P, Len, '0')
 144 #elif defined COMPILE_WIDE
 145 # define memset_space(P, Len) (wmemset (P, L' ', Len), (P) += (Len))
 146 # define memset_zero(P, Len) (wmemset (P, L'0', Len), (P) += (Len))
 147 #else
 148 # define memset_space(P, Len) (memset (P, ' ', Len), (P) += (Len))
 149 # define memset_zero(P, Len) (memset (P, '0', Len), (P) += (Len))
 150 #endif
 151
 152 #if FPRINTFTIME
 153 # define advance(P, N)
 154 #else
 155 # define advance(P, N) ((P) += (N))
 156 #endif
 157
 158 #define add(n, f) width_add (width, n, f)
 159 #define width_add(width, n, f)                                                \
 160   do                                                                          \
 161     {                                                                         \
 162       size_t _n = (n);                                                        \
 163       size_t _w = pad == L_('-') || width < 0 ? 0 : width;                    \
 164       size_t _incr = _n < _w ? _w : _n;                                       \
 165       if (_incr >= maxsize - i)                                               \
 166         {                                                                     \
 167           errno = ERANGE;                                                     \
 168           return 0;                                                           \
 169         }                                                                     \
 170       if (p)                                                                  \
 171         {                                                                     \
 172           if (_n < _w)                                                        \
 173             {                                                                 \
 174               size_t _delta = _w - _n;                                        \
 175               if (pad == L_('0') || pad == L_('+'))                           \
 176                 memset_zero (p, _delta);                                      \
 177               else                                                            \
 178                 memset_space (p, _delta);                                     \
 179             }                                                                 \
 180           f;                                                                  \
 181           advance (p, _n);                                                    \
 182         }                                                                     \
 183       i += _incr;                                                             \
 184     } while (0)
 185
 186 #define add1(c) width_add1 (width, c)
 187 #if FPRINTFTIME
 188 # define width_add1(width, c) width_add (width, 1, fputc (c, p))
 189 #else
 190 # define width_add1(width, c) width_add (width, 1, *p = c)
 191 #endif
 192
 193 #define cpy(n, s) width_cpy (width, n, s)
 194 #if FPRINTFTIME
 195 # define width_cpy(width, n, s)                                               \
 196     width_add (width, n,                                                      \
 197      do                                                                       \
 198        {                                                                      \
 199          if (to_lowcase)                                                      \
 200            fwrite_lowcase (p, (s), _n);                                       \
 201          else if (to_uppcase)                                                 \
 202            fwrite_uppcase (p, (s), _n);                                       \
 203          else                                                                 \
 204            {                                                                  \
 205              /* Ignore the value of fwrite.  The caller can determine whether \
 206                 an error occurred by inspecting ferror (P).  All known fwrite \
 207                 implementations set the stream's error indicator when they    \
 208                 fail due to ENOMEM etc., even though C11 and POSIX.1-2008 do  \
 209                 not require this.  */                                         \
 210              fwrite (s, _n, 1, p);                                            \
 211            }                                                                  \
 212        }                                                                      \
 213      while (0)                                                                \
 214     )
 215 #else
 216 # define width_cpy(width, n, s)                                               \
 217     width_add (width, n,                                                      \
 218          if (to_lowcase)                                                      \
 219            memcpy_lowcase (p, (s), _n LOCALE_ARG);                            \
 220          else if (to_uppcase)                                                 \
 221            memcpy_uppcase (p, (s), _n LOCALE_ARG);                            \
 222          else                                                                 \
 223            MEMCPY ((void *) p, (void const *) (s), _n))
 224 #endif
 225
 226 #ifdef COMPILE_WIDE
 227 # ifndef USE_IN_EXTENDED_LOCALE_MODEL
 228 #  undef __mbsrtowcs_l
 229 #  define __mbsrtowcs_l(d, s, l, st, loc) __mbsrtowcs (d, s, l, st)
 230 # endif
 231 # define widen(os, ws, l) \
 232   {                                                                           \
 233     mbstate_t __st;                                                           \
 234     const char *__s = os;                                                     \
 235     memset (&__st, '\0', sizeof (__st));                                      \
 236     l = __mbsrtowcs_l (NULL, &__s, 0, &__st, loc);                            \
 237     ws = (wchar_t *) alloca ((l + 1) * sizeof (wchar_t));                     \
 238     (void) __mbsrtowcs_l (ws, &__s, l, &__st, loc);                           \
 239   }
 240 #endif
 241
 242
 243 #if defined _LIBC && defined USE_IN_EXTENDED_LOCALE_MODEL
 244 /* We use this code also for the extended locale handling where the
 245    function gets as an additional argument the locale which has to be
 246    used.  To access the values we have to redefine the _NL_CURRENT
 247    macro.  */
 248 # define strftime               __strftime_l
 249 # define wcsftime               __wcsftime_l
 250 # undef _NL_CURRENT
 251 # define _NL_CURRENT(category, item) \
 252   (current->values[_NL_ITEM_INDEX (item)].string)
 253 # define LOCALE_PARAM , locale_t loc
 254 # define LOCALE_ARG , loc
 255 # define HELPER_LOCALE_ARG  , current
 256 #else
 257 # define LOCALE_PARAM
 258 # define LOCALE_ARG
 259 # ifdef _LIBC
 260 #  define HELPER_LOCALE_ARG , _NL_CURRENT_DATA (LC_TIME)
 261 # else
 262 #  define HELPER_LOCALE_ARG
 263 # endif
 264 #endif
 265
 266 #ifdef COMPILE_WIDE
 267 # ifdef USE_IN_EXTENDED_LOCALE_MODEL
 268 #  define TOUPPER(Ch, L) __towupper_l (Ch, L)
 269 #  define TOLOWER(Ch, L) __towlower_l (Ch, L)
 270 # else
 271 #  define TOUPPER(Ch, L) towupper (Ch)
 272 #  define TOLOWER(Ch, L) towlower (Ch)
 273 # endif
 274 #else
 275 # ifdef USE_IN_EXTENDED_LOCALE_MODEL
 276 #  define TOUPPER(Ch, L) __toupper_l (Ch, L)
 277 #  define TOLOWER(Ch, L) __tolower_l (Ch, L)
 278 # else
 279 #  define TOUPPER(Ch, L) toupper (Ch)
 280 #  define TOLOWER(Ch, L) tolower (Ch)
 281 # endif
 282 #endif
 283 /* We don't use 'isdigit' here since the locale dependent
 284    interpretation is not what we want here.  We only need to accept
 285    the arabic digits in the ASCII range.  One day there is perhaps a
 286    more reliable way to accept other sets of digits.  */
 287 #define ISDIGIT(Ch) ((unsigned int) (Ch) - L_('0') <= 9)
 288
 289 #if FPRINTFTIME
 290 static void
 291 fwrite_lowcase (FILE *fp, const CHAR_T *src, size_t len)
 292 {
 293   while (len-- > 0)
 294     {
 295       fputc (TOLOWER ((UCHAR_T) *src, loc), fp);
 296       ++src;
 297     }
 298 }
 299
 300 static void
 301 fwrite_uppcase (FILE *fp, const CHAR_T *src, size_t len)
 302 {
 303   while (len-- > 0)
 304     {
 305       fputc (TOUPPER ((UCHAR_T) *src, loc), fp);
 306       ++src;
 307     }
 308 }
 309 #else
 310 static CHAR_T *memcpy_lowcase (CHAR_T *dest, const CHAR_T *src,
 311                                size_t len LOCALE_PARAM);
 312
 313 static CHAR_T *
 314 memcpy_lowcase (CHAR_T *dest, const CHAR_T *src, size_t len LOCALE_PARAM)
 315 {
 316   while (len-- > 0)
 317     dest[len] = TOLOWER ((UCHAR_T) src[len], loc);
 318   return dest;
 319 }
 320
 321 static CHAR_T *memcpy_uppcase (CHAR_T *dest, const CHAR_T *src,
 322                                size_t len LOCALE_PARAM);
 323
 324 static CHAR_T *
 325 memcpy_uppcase (CHAR_T *dest, const CHAR_T *src, size_t len LOCALE_PARAM)
 326 {
 327   while (len-- > 0)
 328     dest[len] = TOUPPER ((UCHAR_T) src[len], loc);
 329   return dest;
 330 }
 331 #endif
 332
 333
 334 #if ! HAVE_TM_GMTOFF
 335 /* Yield the difference between *A and *B,
 336    measured in seconds, ignoring leap seconds.  */
 337 # define tm_diff ftime_tm_diff
 338 static int tm_diff (const struct tm *, const struct tm *);
 339 static int
 340 tm_diff (const struct tm *a, const struct tm *b)
 341 {
 342   /* Compute intervening leap days correctly even if year is negative.
 343      Take care to avoid int overflow in leap day calculations,
 344      but it's OK to assume that A and B are close to each other.  */
 345   int a4 = SHR (a->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (a->tm_year & 3);
 346   int b4 = SHR (b->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (b->tm_year & 3);
 347   int a100 = (a4 + (a4 < 0)) / 25 - (a4 < 0);
 348   int b100 = (b4 + (b4 < 0)) / 25 - (b4 < 0);
 349   int a400 = SHR (a100, 2);
 350   int b400 = SHR (b100, 2);
 351   int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
 352   int years = a->tm_year - b->tm_year;
 353   int days = (365 * years + intervening_leap_days
 354               + (a->tm_yday - b->tm_yday));
 355   return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
 356                 + (a->tm_min - b->tm_min))
 357           + (a->tm_sec - b->tm_sec));
 358 }
 359 #endif /* ! HAVE_TM_GMTOFF */
 360
 361
 362
 363 /* The number of days from the first day of the first ISO week of this
 364    year to the year day YDAY with week day WDAY.  ISO weeks start on
 365    Monday; the first ISO week has the year's first Thursday.  YDAY may
 366    be as small as YDAY_MINIMUM.  */
 367 #define ISO_WEEK_START_WDAY 1 /* Monday */
 368 #define ISO_WEEK1_WDAY 4 /* Thursday */
 369 #define YDAY_MINIMUM (-366)
 370 static int iso_week_days (int, int);
 371 #if defined __GNUC__ || defined __clang__
 372 __inline__
 373 #endif
 374 static int
 375 iso_week_days (int yday, int wday)
 376 {
 377   /* Add enough to the first operand of % to make it nonnegative.  */
 378   int big_enough_multiple_of_7 = (-YDAY_MINIMUM / 7 + 2) * 7;
 379   return (yday
 380           - (yday - wday + ISO_WEEK1_WDAY + big_enough_multiple_of_7) % 7
 381           + ISO_WEEK1_WDAY - ISO_WEEK_START_WDAY);
 382 }
 383
 384
 385 /* When compiling this file, GNU applications can #define my_strftime
 386    to a symbol (typically nstrftime) to get an extended strftime with
 387    extra arguments TZ and NS.  */
 388
 389 #if FPRINTFTIME
 390 # undef my_strftime
 391 # define my_strftime fprintftime
 392 #endif
 393
 394 #ifdef my_strftime
 395 # define extra_args , tz, ns
 396 # define extra_args_spec , timezone_t tz, int ns
 397 #else
 398 # if defined COMPILE_WIDE
 399 #  define my_strftime wcsftime
 400 #  define nl_get_alt_digit _nl_get_walt_digit
 401 # else
 402 #  define my_strftime strftime
 403 #  define nl_get_alt_digit _nl_get_alt_digit
 404 # endif
 405 # define extra_args
 406 # define extra_args_spec
 407 /* We don't have this information in general.  */
 408 # define tz 1
 409 # define ns 0
 410 #endif
 411
 412 static size_t __strftime_internal (STREAM_OR_CHAR_T *, STRFTIME_ARG (size_t)
 413                                    const CHAR_T *, const struct tm *,
 414                                    bool, int, int, bool *
 415                                    extra_args_spec LOCALE_PARAM);
 416
 417 /* Write information from TP into S according to the format
 418    string FORMAT, writing no more that MAXSIZE characters
 419    (including the terminating '\0') and returning number of
 420    characters written.  If S is NULL, nothing will be written
 421    anywhere, so to determine how many characters would be
 422    written, use NULL for S and (size_t) -1 for MAXSIZE.  */
 423 size_t
 424 my_strftime (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
 425              const CHAR_T *format,
 426              const struct tm *tp extra_args_spec LOCALE_PARAM)
 427 {
 428   bool tzset_called = false;
 429   return __strftime_internal (s, STRFTIME_ARG (maxsize) format, tp, false,
 430                               0, -1, &tzset_called extra_args LOCALE_ARG);
 431 }
 432 #if defined _LIBC && ! FPRINTFTIME
 433 libc_hidden_def (my_strftime)
 434 #endif
 435
 436 /* Just like my_strftime, above, but with more parameters.
 437    UPCASE indicates that the result should be converted to upper case.
 438    YR_SPEC and WIDTH specify the padding and width for the year.
 439    *TZSET_CALLED indicates whether tzset has been called here.  */
 440 static size_t
 441 __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
 442                      const CHAR_T *format,
 443                      const struct tm *tp, bool upcase,
 444                      int yr_spec, int width, bool *tzset_called
 445                      extra_args_spec LOCALE_PARAM)
 446 {
 447 #if defined _LIBC && defined USE_IN_EXTENDED_LOCALE_MODEL
 448   struct __locale_data *const current = loc->__locales[LC_TIME];
 449 #endif
 450 #if FPRINTFTIME
 451   size_t maxsize = (size_t) -1;
 452 #endif
 453
 454   int saved_errno = errno;
 455   int hour12 = tp->tm_hour;
 456 #ifdef _NL_CURRENT
 457   /* We cannot make the following values variables since we must delay
 458      the evaluation of these values until really needed since some
 459      expressions might not be valid in every situation.  The 'struct tm'
 460      might be generated by a strptime() call that initialized
 461      only a few elements.  Dereference the pointers only if the format
 462      requires this.  Then it is ok to fail if the pointers are invalid.  */
 463 # define a_wkday \
 464   ((const CHAR_T *) (tp->tm_wday < 0 || tp->tm_wday > 6                      \
 465                      ? "?" : _NL_CURRENT (LC_TIME, NLW(ABDAY_1) + tp->tm_wday)))
 466 # define f_wkday \
 467   ((const CHAR_T *) (tp->tm_wday < 0 || tp->tm_wday > 6                      \
 468                      ? "?" : _NL_CURRENT (LC_TIME, NLW(DAY_1) + tp->tm_wday)))
 469 # define a_month \
 470   ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                       \
 471                      ? "?" : _NL_CURRENT (LC_TIME, NLW(ABMON_1) + tp->tm_mon)))
 472 # define f_month \
 473   ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                       \
 474                      ? "?" : _NL_CURRENT (LC_TIME, NLW(MON_1) + tp->tm_mon)))
 475 # define a_altmonth \
 476   ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                       \
 477                      ? "?" : _NL_CURRENT (LC_TIME, NLW(ABALTMON_1) + tp->tm_mon)))
 478 # define f_altmonth \
 479   ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                       \
 480                      ? "?" : _NL_CURRENT (LC_TIME, NLW(ALTMON_1) + tp->tm_mon)))
 481 # define ampm \
 482   ((const CHAR_T *) _NL_CURRENT (LC_TIME, tp->tm_hour > 11                    \
 483                                  ? NLW(PM_STR) : NLW(AM_STR)))
 484
 485 # define aw_len STRLEN (a_wkday)
 486 # define am_len STRLEN (a_month)
 487 # define aam_len STRLEN (a_altmonth)
 488 # define ap_len STRLEN (ampm)
 489 #endif
 490 #if HAVE_TZNAME
 491   char **tzname_vec = tzname;
 492 #endif
 493   const char *zone;
 494   size_t i = 0;
 495   STREAM_OR_CHAR_T *p = s;
 496   const CHAR_T *f;
 497 #if DO_MULTIBYTE && !defined COMPILE_WIDE
 498   const char *format_end = NULL;
 499 #endif
 500
 501   zone = NULL;
 502 #if HAVE_TM_ZONE
 503   /* The POSIX test suite assumes that setting
 504      the environment variable TZ to a new value before calling strftime()
 505      will influence the result (the %Z format) even if the information in
 506      TP is computed with a totally different time zone.
 507      This is bogus: though POSIX allows bad behavior like this,
 508      POSIX does not require it.  Do the right thing instead.  */
 509   zone = (const char *) tp->tm_zone;
 510 #endif
 511 #if HAVE_TZNAME
 512   if (!tz)
 513     {
 514       if (! (zone && *zone))
 515         zone = "GMT";
 516     }
 517   else
 518     {
 519 # if !HAVE_TM_ZONE
 520       /* Infer the zone name from *TZ instead of from TZNAME.  */
 521       tzname_vec = tz->tzname_copy;
 522 # endif
 523     }
 524   /* The tzset() call might have changed the value.  */
 525   if (!(zone && *zone) && tp->tm_isdst >= 0)
 526     {
 527       /* POSIX.1 requires that local time zone information be used as
 528          though strftime called tzset.  */
 529 # ifndef my_strftime
 530       if (!*tzset_called)
 531         {
 532           tzset ();
 533           *tzset_called = true;
 534         }
 535 # endif
 536       zone = tzname_vec[tp->tm_isdst != 0];
 537     }
 538 #endif
 539   if (! zone)
 540     zone = "";
 541
 542   if (hour12 > 12)
 543     hour12 -= 12;
 544   else
 545     if (hour12 == 0)
 546       hour12 = 12;
 547
 548   for (f = format; *f != '\0'; width = -1, f++)
 549     {
 550       int pad = 0;  /* Padding for number ('_', '-', '+', '0', or 0).  */
 551       int modifier;             /* Field modifier ('E', 'O', or 0).  */
 552       int digits = 0;           /* Max digits for numeric format.  */
 553       int number_value;         /* Numeric value to be printed.  */
 554       unsigned int u_number_value; /* (unsigned int) number_value.  */
 555       bool negative_number;     /* The number is negative.  */
 556       bool always_output_a_sign; /* +/- should always be output.  */
 557       int tz_colon_mask;        /* Bitmask of where ':' should appear.  */
 558       const CHAR_T *subfmt;
 559       CHAR_T *bufp;
 560       CHAR_T buf[1
 561                  + 2 /* for the two colons in a %::z or %:::z time zone */
 562                  + (sizeof (int) < sizeof (time_t)
 563                     ? INT_STRLEN_BOUND (time_t)
 564                     : INT_STRLEN_BOUND (int))];
 565       bool to_lowcase = false;
 566       bool to_uppcase = upcase;
 567       size_t colons;
 568       bool change_case = false;
 569       int format_char;
 570       int subwidth;
 571
 572 #if DO_MULTIBYTE && !defined COMPILE_WIDE
 573       switch (*f)
 574         {
 575         case L_('%'):
 576           break;
 577
 578         case L_('\b'): case L_('\t'): case L_('\n'):
 579         case L_('\v'): case L_('\f'): case L_('\r'):
 580         case L_(' '): case L_('!'): case L_('"'): case L_('#'): case L_('&'):
 581         case L_('\''): case L_('('): case L_(')'): case L_('*'): case L_('+'):
 582         case L_(','): case L_('-'): case L_('.'): case L_('/'): case L_('0'):
 583         case L_('1'): case L_('2'): case L_('3'): case L_('4'): case L_('5'):
 584         case L_('6'): case L_('7'): case L_('8'): case L_('9'): case L_(':'):
 585         case L_(';'): case L_('<'): case L_('='): case L_('>'): case L_('?'):
 586         case L_('A'): case L_('B'): case L_('C'): case L_('D'): case L_('E'):
 587         case L_('F'): case L_('G'): case L_('H'): case L_('I'): case L_('J'):
 588         case L_('K'): case L_('L'): case L_('M'): case L_('N'): case L_('O'):
 589         case L_('P'): case L_('Q'): case L_('R'): case L_('S'): case L_('T'):
 590         case L_('U'): case L_('V'): case L_('W'): case L_('X'): case L_('Y'):
 591         case L_('Z'): case L_('['): case L_('\\'): case L_(']'): case L_('^'):
 592         case L_('_'): case L_('a'): case L_('b'): case L_('c'): case L_('d'):
 593         case L_('e'): case L_('f'): case L_('g'): case L_('h'): case L_('i'):
 594         case L_('j'): case L_('k'): case L_('l'): case L_('m'): case L_('n'):
 595         case L_('o'): case L_('p'): case L_('q'): case L_('r'): case L_('s'):
 596         case L_('t'): case L_('u'): case L_('v'): case L_('w'): case L_('x'):
 597         case L_('y'): case L_('z'): case L_('{'): case L_('|'): case L_('}'):
 598         case L_('~'):
 599           /* The C Standard requires these 98 characters (plus '%') to
 600              be in the basic execution character set.  None of these
 601              characters can start a multibyte sequence, so they need
 602              not be analyzed further.  */
 603           add1 (*f);
 604           continue;
 605
 606         default:
 607           /* Copy this multibyte sequence until we reach its end, find
 608              an error, or come back to the initial shift state.  */
 609           {
 610             mbstate_t mbstate = mbstate_zero;
 611             size_t len = 0;
 612             size_t fsize;
 613
 614             if (! format_end)
 615               format_end = f + strlen (f) + 1;
 616             fsize = format_end - f;
 617
 618             do
 619               {
 620                 size_t bytes = mbrlen (f + len, fsize - len, &mbstate);
 621
 622                 if (bytes == 0)
 623                   break;
 624
 625                 if (bytes == (size_t) -2)
 626                   {
 627                     len += strlen (f + len);
 628                     break;
 629                   }
 630
 631                 if (bytes == (size_t) -1)
 632                   {
 633                     len++;
 634                     break;
 635                   }
 636
 637                 len += bytes;
 638               }
 639             while (! mbsinit (&mbstate));
 640
 641             cpy (len, f);
 642             f += len - 1;
 643             continue;
 644           }
 645         }
 646
 647 #else /* ! DO_MULTIBYTE */
 648
 649       /* Either multibyte encodings are not supported, they are
 650          safe for formats, so any non-'%' byte can be copied through,
 651          or this is the wide character version.  */
 652       if (*f != L_('%'))
 653         {
 654           add1 (*f);
 655           continue;
 656         }
 657
 658 #endif /* ! DO_MULTIBYTE */
 659
 660       /* Check for flags that can modify a format.  */
 661       while (1)
 662         {
 663           switch (*++f)
 664             {
 665               /* This influences the number formats.  */
 666             case L_('_'):
 667             case L_('-'):
 668             case L_('+'):
 669             case L_('0'):
 670               pad = *f;
 671               continue;
 672
 673               /* This changes textual output.  */
 674             case L_('^'):
 675               to_uppcase = true;
 676               continue;
 677             case L_('#'):
 678               change_case = true;
 679               continue;
 680
 681             default:
 682               break;
 683             }
 684           break;
 685         }
 686
 687       if (ISDIGIT (*f))
 688         {
 689           width = 0;
 690           do
 691             {
 692               if (INT_MULTIPLY_WRAPV (width, 10, &width)
 693                   || INT_ADD_WRAPV (width, *f - L_('0'), &width))
 694                 width = INT_MAX;
 695               ++f;
 696             }
 697           while (ISDIGIT (*f));
 698         }
 699
 700       /* Check for modifiers.  */
 701       switch (*f)
 702         {
 703         case L_('E'):
 704         case L_('O'):
 705           modifier = *f++;
 706           break;
 707
 708         default:
 709           modifier = 0;
 710           break;
 711         }
 712
 713       /* Now do the specified format.  */
 714       format_char = *f;
 715       switch (format_char)
 716         {
 717 #define DO_NUMBER(d, v) \
 718           do                                                                  \
 719             {                                                                 \
 720               digits = d;                                                     \
 721               number_value = v;                                               \
 722               goto do_number;                                                 \
 723             }                                                                 \
 724           while (0)
 725 #define DO_SIGNED_NUMBER(d, negative, v) \
 726           DO_MAYBE_SIGNED_NUMBER (d, negative, v, do_signed_number)
 727 #define DO_YEARISH(d, negative, v) \
 728           DO_MAYBE_SIGNED_NUMBER (d, negative, v, do_yearish)
 729 #define DO_MAYBE_SIGNED_NUMBER(d, negative, v, label) \
 730           do                                                                  \
 731             {                                                                 \
 732               digits = d;                                                     \
 733               negative_number = negative;                                     \
 734               u_number_value = v;                                             \
 735               goto label;                                                     \
 736             }                                                                 \
 737           while (0)
 738
 739           /* The mask is not what you might think.
 740              When the ordinal i'th bit is set, insert a colon
 741              before the i'th digit of the time zone representation.  */
 742 #define DO_TZ_OFFSET(d, mask, v) \
 743           do                                                                  \
 744             {                                                                 \
 745               digits = d;                                                     \
 746               tz_colon_mask = mask;                                           \
 747               u_number_value = v;                                             \
 748               goto do_tz_offset;                                              \
 749             }                                                                 \
 750           while (0)
 751 #define DO_NUMBER_SPACEPAD(d, v) \
 752           do                                                                  \
 753             {                                                                 \
 754               digits = d;                                                     \
 755               number_value = v;                                               \
 756               goto do_number_spacepad;                                        \
 757             }                                                                 \
 758           while (0)
 759
 760         case L_('%'):
 761           if (modifier != 0)
 762             goto bad_format;
 763           add1 (*f);
 764           break;
 765
 766         case L_('a'):
 767           if (modifier != 0)
 768             goto bad_format;
 769           if (change_case)
 770             {
 771               to_uppcase = true;
 772               to_lowcase = false;
 773             }
 774 #ifdef _NL_CURRENT
 775           cpy (aw_len, a_wkday);
 776           break;
 777 #else
 778           goto underlying_strftime;
 779 #endif
 780
 781         case 'A':
 782           if (modifier != 0)
 783             goto bad_format;
 784           if (change_case)
 785             {
 786               to_uppcase = true;
 787               to_lowcase = false;
 788             }
 789 #ifdef _NL_CURRENT
 790           cpy (STRLEN (f_wkday), f_wkday);
 791           break;
 792 #else
 793           goto underlying_strftime;
 794 #endif
 795
 796         case L_('b'):
 797         case L_('h'):
 798           if (change_case)
 799             {
 800               to_uppcase = true;
 801               to_lowcase = false;
 802             }
 803           if (modifier == L_('E'))
 804             goto bad_format;
 805 #ifdef _NL_CURRENT
 806           if (modifier == L_('O'))
 807             cpy (aam_len, a_altmonth);
 808           else
 809             cpy (am_len, a_month);
 810           break;
 811 #else
 812           goto underlying_strftime;
 813 #endif
 814
 815         case L_('B'):
 816           if (modifier == L_('E'))
 817             goto bad_format;
 818           if (change_case)
 819             {
 820               to_uppcase = true;
 821               to_lowcase = false;
 822             }
 823 #ifdef _NL_CURRENT
 824           if (modifier == L_('O'))
 825             cpy (STRLEN (f_altmonth), f_altmonth);
 826           else
 827             cpy (STRLEN (f_month), f_month);
 828           break;
 829 #else
 830           goto underlying_strftime;
 831 #endif
 832
 833         case L_('c'):
 834           if (modifier == L_('O'))
 835             goto bad_format;
 836 #ifdef _NL_CURRENT
 837           if (! (modifier == L_('E')
 838                  && (*(subfmt =
 839                        (const CHAR_T *) _NL_CURRENT (LC_TIME,
 840                                                      NLW(ERA_D_T_FMT)))
 841                      != '\0')))
 842             subfmt = (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(D_T_FMT));
 843 #else
 844           goto underlying_strftime;
 845 #endif
 846
 847         subformat:
 848           subwidth = -1;
 849         subformat_width:
 850           {
 851             size_t len = __strftime_internal (NULL, STRFTIME_ARG ((size_t) -1)
 852                                               subfmt, tp, to_uppcase,
 853                                               pad, subwidth, tzset_called
 854                                               extra_args LOCALE_ARG);
 855             add (len, __strftime_internal (p,
 856                                            STRFTIME_ARG (maxsize - i)
 857                                            subfmt, tp, to_uppcase,
 858                                            pad, subwidth, tzset_called
 859                                            extra_args LOCALE_ARG));
 860           }
 861           break;
 862
 863 #if !(defined _NL_CURRENT && HAVE_STRUCT_ERA_ENTRY)
 864         underlying_strftime:
 865           {
 866             /* The relevant information is available only via the
 867                underlying strftime implementation, so use that.  */
 868             char ufmt[5];
 869             char *u = ufmt;
 870             char ubuf[1024]; /* enough for any single format in practice */
 871             size_t len;
 872             /* Make sure we're calling the actual underlying strftime.
 873                In some cases, config.h contains something like
 874                "#define strftime rpl_strftime".  */
 875 # ifdef strftime
 876 #  undef strftime
 877             size_t strftime ();
 878 # endif
 879
 880             /* The space helps distinguish strftime failure from empty
 881                output.  */
 882             *u++ = ' ';
 883             *u++ = '%';
 884             if (modifier != 0)
 885               *u++ = modifier;
 886             *u++ = format_char;
 887             *u = '\0';
 888             len = strftime (ubuf, sizeof ubuf, ufmt, tp);
 889             if (len != 0)
 890               cpy (len - 1, ubuf + 1);
 891           }
 892           break;
 893 #endif
 894
 895         case L_('C'):
 896           if (modifier == L_('E'))
 897             {
 898 #if HAVE_STRUCT_ERA_ENTRY
 899               struct era_entry *era = _nl_get_era_entry (tp HELPER_LOCALE_ARG);
 900               if (era)
 901                 {
 902 # ifdef COMPILE_WIDE
 903                   size_t len = __wcslen (era->era_wname);
 904                   cpy (len, era->era_wname);
 905 # else
 906                   size_t len = strlen (era->era_name);
 907                   cpy (len, era->era_name);
 908 # endif
 909                   break;
 910                 }
 911 #else
 912               goto underlying_strftime;
 913 #endif
 914             }
 915
 916           {
 917             bool negative_year = tp->tm_year < - TM_YEAR_BASE;
 918             bool zero_thru_1899 = !negative_year & (tp->tm_year < 0);
 919             int century = ((tp->tm_year - 99 * zero_thru_1899) / 100
 920                            + TM_YEAR_BASE / 100);
 921             DO_YEARISH (2, negative_year, century);
 922           }
 923
 924         case L_('x'):
 925           if (modifier == L_('O'))
 926             goto bad_format;
 927 #ifdef _NL_CURRENT
 928           if (! (modifier == L_('E')
 929                  && (*(subfmt =
 930                        (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(ERA_D_FMT)))
 931                      != L_('\0'))))
 932             subfmt = (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(D_FMT));
 933           goto subformat;
 934 #else
 935           goto underlying_strftime;
 936 #endif
 937         case L_('D'):
 938           if (modifier != 0)
 939             goto bad_format;
 940           subfmt = L_("%m/%d/%y");
 941           goto subformat;
 942
 943         case L_('d'):
 944           if (modifier == L_('E'))
 945             goto bad_format;
 946
 947           DO_NUMBER (2, tp->tm_mday);
 948
 949         case L_('e'):
 950           if (modifier == L_('E'))
 951             goto bad_format;
 952
 953           DO_NUMBER_SPACEPAD (2, tp->tm_mday);
 954
 955           /* All numeric formats set DIGITS and NUMBER_VALUE (or U_NUMBER_VALUE)
 956              and then jump to one of these labels.  */
 957
 958         do_tz_offset:
 959           always_output_a_sign = true;
 960           goto do_number_body;
 961
 962         do_yearish:
 963           if (pad == 0)
 964             pad = yr_spec;
 965           always_output_a_sign
 966             = (pad == L_('+')
 967                && ((digits == 2 ? 99 : 9999) < u_number_value
 968                    || digits < width));
 969           goto do_maybe_signed_number;
 970
 971         do_number_spacepad:
 972           if (pad == 0)
 973             pad = L_('_');
 974
 975         do_number:
 976           /* Format NUMBER_VALUE according to the MODIFIER flag.  */
 977           negative_number = number_value < 0;
 978           u_number_value = number_value;
 979
 980         do_signed_number:
 981           always_output_a_sign = false;
 982
 983         do_maybe_signed_number:
 984           tz_colon_mask = 0;
 985
 986         do_number_body:
 987           /* Format U_NUMBER_VALUE according to the MODIFIER flag.
 988              NEGATIVE_NUMBER is nonzero if the original number was
 989              negative; in this case it was converted directly to
 990              unsigned int (i.e., modulo (UINT_MAX + 1)) without
 991              negating it.  */
 992           if (modifier == L_('O') && !negative_number)
 993             {
 994 #ifdef _NL_CURRENT
 995               /* Get the locale specific alternate representation of
 996                  the number.  If none exist NULL is returned.  */
 997               const CHAR_T *cp = nl_get_alt_digit (u_number_value
 998                                                    HELPER_LOCALE_ARG);
 999
1000               if (cp != NULL)
1001                 {
1002                   size_t digitlen = STRLEN (cp);
1003                   if (digitlen != 0)
1004                     {
1005                       cpy (digitlen, cp);
1006                       break;
1007                     }
1008                 }
1009 #else
1010               goto underlying_strftime;
1011 #endif
1012             }
1013
1014           bufp = buf + sizeof (buf) / sizeof (buf[0]);
1015
1016           if (negative_number)
1017             u_number_value = - u_number_value;
1018
1019           do
1020             {
1021               if (tz_colon_mask & 1)
1022                 *--bufp = ':';
1023               tz_colon_mask >>= 1;
1024               *--bufp = u_number_value % 10 + L_('0');
1025               u_number_value /= 10;
1026             }
1027           while (u_number_value != 0 || tz_colon_mask != 0);
1028
1029         do_number_sign_and_padding:
1030           if (pad == 0)
1031             pad = L_('0');
1032           if (width < 0)
1033             width = digits;
1034
1035           {
1036             CHAR_T sign_char = (negative_number ? L_('-')
1037                                 : always_output_a_sign ? L_('+')
1038                                 : 0);
1039             int numlen = buf + sizeof buf / sizeof buf[0] - bufp;
1040             int shortage = width - !!sign_char - numlen;
1041             int padding = pad == L_('-') || shortage <= 0 ? 0 : shortage;
1042
1043             if (sign_char)
1044               {
1045                 if (pad == L_('_'))
1046                   {
1047                     if (p)
1048                       memset_space (p, padding);
1049                     i += padding;
1050                     width -= padding;
1051                   }
1052                 width_add1 (0, sign_char);
1053                 width--;
1054               }
1055
1056             cpy (numlen, bufp);
1057           }
1058           break;
1059
1060         case L_('F'):
1061           if (modifier != 0)
1062             goto bad_format;
1063           if (pad == 0 && width < 0)
1064             {
1065               pad = L_('+');
1066               subwidth = 4;
1067             }
1068           else
1069             {
1070               subwidth = width - 6;
1071               if (subwidth < 0)
1072                 subwidth = 0;
1073             }
1074           subfmt = L_("%Y-%m-%d");
1075           goto subformat_width;
1076
1077         case L_('H'):
1078           if (modifier == L_('E'))
1079             goto bad_format;
1080
1081           DO_NUMBER (2, tp->tm_hour);
1082
1083         case L_('I'):
1084           if (modifier == L_('E'))
1085             goto bad_format;
1086
1087           DO_NUMBER (2, hour12);
1088
1089         case L_('k'):           /* GNU extension.  */
1090           if (modifier == L_('E'))
1091             goto bad_format;
1092
1093           DO_NUMBER_SPACEPAD (2, tp->tm_hour);
1094
1095         case L_('l'):           /* GNU extension.  */
1096           if (modifier == L_('E'))
1097             goto bad_format;
1098
1099           DO_NUMBER_SPACEPAD (2, hour12);
1100
1101         case L_('j'):
1102           if (modifier == L_('E'))
1103             goto bad_format;
1104
1105           DO_SIGNED_NUMBER (3, tp->tm_yday < -1, tp->tm_yday + 1U);
1106
1107         case L_('M'):
1108           if (modifier == L_('E'))
1109             goto bad_format;
1110
1111           DO_NUMBER (2, tp->tm_min);
1112
1113         case L_('m'):
1114           if (modifier == L_('E'))
1115             goto bad_format;
1116
1117           DO_SIGNED_NUMBER (2, tp->tm_mon < -1, tp->tm_mon + 1U);
1118
1119 #ifndef _LIBC
1120         case L_('N'):           /* GNU extension.  */
1121           if (modifier == L_('E'))
1122             goto bad_format;
1123           {
1124             int n = ns, ns_digits = 9;
1125             if (width <= 0)
1126               width = ns_digits;
1127             int ndigs = ns_digits;
1128             while (width < ndigs || (1 < ndigs && n % 10 == 0))
1129               ndigs--, n /= 10;
1130             for (int j = ndigs; 0 < j; j--)
1131               buf[j - 1] = n % 10 + L_('0'), n /= 10;
1132             if (!pad)
1133               pad = L_('0');
1134             width_cpy (0, ndigs, buf);
1135             width_add (width - ndigs, 0, (void) 0);
1136           }
1137           break;
1138 #endif
1139
1140         case L_('n'):
1141           add1 (L_('\n'));
1142           break;
1143
1144         case L_('P'):
1145           to_lowcase = true;
1146 #ifndef _NL_CURRENT
1147           format_char = L_('p');
1148 #endif
1149           FALLTHROUGH;
1150         case L_('p'):
1151           if (change_case)
1152             {
1153               to_uppcase = false;
1154               to_lowcase = true;
1155             }
1156 #ifdef _NL_CURRENT
1157           cpy (ap_len, ampm);
1158           break;
1159 #else
1160           goto underlying_strftime;
1161 #endif
1162
1163         case L_('q'):           /* GNU extension.  */
1164           DO_SIGNED_NUMBER (1, false, ((tp->tm_mon * 11) >> 5) + 1);
1165           break;
1166
1167         case L_('R'):
1168           subfmt = L_("%H:%M");
1169           goto subformat;
1170
1171         case L_('r'):
1172 #ifdef _NL_CURRENT
1173           if (*(subfmt = (const CHAR_T *) _NL_CURRENT (LC_TIME,
1174                                                        NLW(T_FMT_AMPM)))
1175               == L_('\0'))
1176             subfmt = L_("%I:%M:%S %p");
1177           goto subformat;
1178 #else
1179           goto underlying_strftime;
1180 #endif
1181
1182         case L_('S'):
1183           if (modifier == L_('E'))
1184             goto bad_format;
1185
1186           DO_NUMBER (2, tp->tm_sec);
1187
1188         case L_('s'):           /* GNU extension.  */
1189           {
1190             struct tm ltm;
1191             time_t t;
1192
1193             ltm = *tp;
1194             ltm.tm_yday = -1;
1195             t = mktime_z (tz, &ltm);
1196             if (ltm.tm_yday < 0)
1197               {
1198                 errno = EOVERFLOW;
1199                 return 0;
1200               }
1201
1202             /* Generate string value for T using time_t arithmetic;
1203                this works even if sizeof (long) < sizeof (time_t).  */
1204
1205             bufp = buf + sizeof (buf) / sizeof (buf[0]);
1206             negative_number = t < 0;
1207
1208             do
1209               {
1210                 int d = t % 10;
1211                 t /= 10;
1212                 *--bufp = (negative_number ? -d : d) + L_('0');
1213               }
1214             while (t != 0);
1215
1216             digits = 1;
1217             always_output_a_sign = false;
1218             goto do_number_sign_and_padding;
1219           }
1220
1221         case L_('X'):
1222           if (modifier == L_('O'))
1223             goto bad_format;
1224 #ifdef _NL_CURRENT
1225           if (! (modifier == L_('E')
1226                  && (*(subfmt =
1227                        (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(ERA_T_FMT)))
1228                      != L_('\0'))))
1229             subfmt = (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(T_FMT));
1230           goto subformat;
1231 #else
1232           goto underlying_strftime;
1233 #endif
1234         case L_('T'):
1235           subfmt = L_("%H:%M:%S");
1236           goto subformat;
1237
1238         case L_('t'):
1239           add1 (L_('\t'));
1240           break;
1241
1242         case L_('u'):
1243           DO_NUMBER (1, (tp->tm_wday - 1 + 7) % 7 + 1);
1244
1245         case L_('U'):
1246           if (modifier == L_('E'))
1247             goto bad_format;
1248
1249           DO_NUMBER (2, (tp->tm_yday - tp->tm_wday + 7) / 7);
1250
1251         case L_('V'):
1252         case L_('g'):
1253         case L_('G'):
1254           if (modifier == L_('E'))
1255             goto bad_format;
1256           {
1257             /* YEAR is a leap year if and only if (tp->tm_year + TM_YEAR_BASE)
1258                is a leap year, except that YEAR and YEAR - 1 both work
1259                correctly even when (tp->tm_year + TM_YEAR_BASE) would
1260                overflow.  */
1261             int year = (tp->tm_year
1262                         + (tp->tm_year < 0
1263                            ? TM_YEAR_BASE % 400
1264                            : TM_YEAR_BASE % 400 - 400));
1265             int year_adjust = 0;
1266             int days = iso_week_days (tp->tm_yday, tp->tm_wday);
1267
1268             if (days < 0)
1269               {
1270                 /* This ISO week belongs to the previous year.  */
1271                 year_adjust = -1;
1272                 days = iso_week_days (tp->tm_yday + (365 + __isleap (year - 1)),
1273                                       tp->tm_wday);
1274               }
1275             else
1276               {
1277                 int d = iso_week_days (tp->tm_yday - (365 + __isleap (year)),
1278                                        tp->tm_wday);
1279                 if (0 <= d)
1280                   {
1281                     /* This ISO week belongs to the next year.  */
1282                     year_adjust = 1;
1283                     days = d;
1284                   }
1285               }
1286
1287             switch (*f)
1288               {
1289               case L_('g'):
1290                 {
1291                   int yy = (tp->tm_year % 100 + year_adjust) % 100;
1292                   DO_YEARISH (2, false,
1293                               (0 <= yy
1294                                ? yy
1295                                : tp->tm_year < -TM_YEAR_BASE - year_adjust
1296                                ? -yy
1297                                : yy + 100));
1298                 }
1299
1300               case L_('G'):
1301                 DO_YEARISH (4, tp->tm_year < -TM_YEAR_BASE - year_adjust,
1302                             (tp->tm_year + (unsigned int) TM_YEAR_BASE
1303                              + year_adjust));
1304
1305               default:
1306                 DO_NUMBER (2, days / 7 + 1);
1307               }
1308           }
1309
1310         case L_('W'):
1311           if (modifier == L_('E'))
1312             goto bad_format;
1313
1314           DO_NUMBER (2, (tp->tm_yday - (tp->tm_wday - 1 + 7) % 7 + 7) / 7);
1315
1316         case L_('w'):
1317           if (modifier == L_('E'))
1318             goto bad_format;
1319
1320           DO_NUMBER (1, tp->tm_wday);
1321
1322         case L_('Y'):
1323           if (modifier == L_('E'))
1324             {
1325 #if HAVE_STRUCT_ERA_ENTRY
1326               struct era_entry *era = _nl_get_era_entry (tp HELPER_LOCALE_ARG);
1327               if (era)
1328                 {
1329 # ifdef COMPILE_WIDE
1330                   subfmt = era->era_wformat;
1331 # else
1332                   subfmt = era->era_format;
1333 # endif
1334                   if (pad == 0)
1335                     pad = yr_spec;
1336                   goto subformat;
1337                 }
1338 #else
1339               goto underlying_strftime;
1340 #endif
1341             }
1342           if (modifier == L_('O'))
1343             goto bad_format;
1344
1345           DO_YEARISH (4, tp->tm_year < -TM_YEAR_BASE,
1346                       tp->tm_year + (unsigned int) TM_YEAR_BASE);
1347
1348         case L_('y'):
1349           if (modifier == L_('E'))
1350             {
1351 #if HAVE_STRUCT_ERA_ENTRY
1352               struct era_entry *era = _nl_get_era_entry (tp HELPER_LOCALE_ARG);
1353               if (era)
1354                 {
1355                   int delta = tp->tm_year - era->start_date[0];
1356                   if (pad == 0)
1357                     pad = yr_spec;
1358                   DO_NUMBER (2, (era->offset
1359                                  + delta * era->absolute_direction));
1360                 }
1361 #else
1362               goto underlying_strftime;
1363 #endif
1364             }
1365
1366           {
1367             int yy = tp->tm_year % 100;
1368             if (yy < 0)
1369               yy = tp->tm_year < - TM_YEAR_BASE ? -yy : yy + 100;
1370             DO_YEARISH (2, false, yy);
1371           }
1372
1373         case L_('Z'):
1374           if (change_case)
1375             {
1376               to_uppcase = false;
1377               to_lowcase = true;
1378             }
1379
1380 #ifdef COMPILE_WIDE
1381           {
1382             /* The zone string is always given in multibyte form.  We have
1383                to transform it first.  */
1384             wchar_t *wczone;
1385             size_t len;
1386             widen (zone, wczone, len);
1387             cpy (len, wczone);
1388           }
1389 #else
1390           cpy (strlen (zone), zone);
1391 #endif
1392           break;
1393
1394         case L_(':'):
1395           /* :, ::, and ::: are valid only just before 'z'.
1396              :::: etc. are rejected later.  */
1397           for (colons = 1; f[colons] == L_(':'); colons++)
1398             continue;
1399           if (f[colons] != L_('z'))
1400             goto bad_format;
1401           f += colons;
1402           goto do_z_conversion;
1403
1404         case L_('z'):
1405           colons = 0;
1406
1407         do_z_conversion:
1408           if (tp->tm_isdst < 0)
1409             break;
1410
1411           {
1412             int diff;
1413             int hour_diff;
1414             int min_diff;
1415             int sec_diff;
1416 #if HAVE_TM_GMTOFF
1417             diff = tp->tm_gmtoff;
1418 #else
1419             if (!tz)
1420               diff = 0;
1421             else
1422               {
1423                 struct tm gtm;
1424                 struct tm ltm;
1425                 time_t lt;
1426
1427                 /* POSIX.1 requires that local time zone information be used as
1428                    though strftime called tzset.  */
1429 # ifndef my_strftime
1430                 if (!*tzset_called)
1431                   {
1432                     tzset ();
1433                     *tzset_called = true;
1434                   }
1435 # endif
1436
1437                 ltm = *tp;
1438                 ltm.tm_wday = -1;
1439                 lt = mktime_z (tz, &ltm);
1440                 if (ltm.tm_wday < 0 || ! localtime_rz (0, &lt, &gtm))
1441                   break;
1442                 diff = tm_diff (&ltm, &gtm);
1443               }
1444 #endif
1445
1446             negative_number = diff < 0 || (diff == 0 && *zone == '-');
1447             hour_diff = diff / 60 / 60;
1448             min_diff = diff / 60 % 60;
1449             sec_diff = diff % 60;
1450
1451             switch (colons)
1452               {
1453               case 0: /* +hhmm */
1454                 DO_TZ_OFFSET (5, 0, hour_diff * 100 + min_diff);
1455
1456               case 1: tz_hh_mm: /* +hh:mm */
1457                 DO_TZ_OFFSET (6, 04, hour_diff * 100 + min_diff);
1458
1459               case 2: tz_hh_mm_ss: /* +hh:mm:ss */
1460                 DO_TZ_OFFSET (9, 024,
1461                               hour_diff * 10000 + min_diff * 100 + sec_diff);
1462
1463               case 3: /* +hh if possible, else +hh:mm, else +hh:mm:ss */
1464                 if (sec_diff != 0)
1465                   goto tz_hh_mm_ss;
1466                 if (min_diff != 0)
1467                   goto tz_hh_mm;
1468                 DO_TZ_OFFSET (3, 0, hour_diff);
1469
1470               default:
1471                 goto bad_format;
1472               }
1473           }
1474
1475         case L_('\0'):          /* GNU extension: % at end of format.  */
1476             --f;
1477             FALLTHROUGH;
1478         default:
1479           /* Unknown format; output the format, including the '%',
1480              since this is most likely the right thing to do if a
1481              multibyte string has been misparsed.  */
1482         bad_format:
1483           {
1484             int flen;
1485             for (flen = 1; f[1 - flen] != L_('%'); flen++)
1486               continue;
1487             cpy (flen, &f[1 - flen]);
1488           }
1489           break;
1490         }
1491     }
1492
1493 #if ! FPRINTFTIME
1494   if (p && maxsize != 0)
1495     *p = L_('\0');
1496 #endif
1497
1498   errno = saved_errno;
1499   return i;
1500 }