aboutsummaryrefslogtreecommitdiff
path: root/time/strftime.c
blob: 7837373aed657707f3d70e125e65a6033336cb69 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
/* Copyright (C) 1991, 92, 93, 94, 95, 96 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
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#ifdef _LIBC
# define HAVE_LIMITS_H 1
# define HAVE_MBLEN 1
# define HAVE_MBRLEN 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 <sys/types.h>		/* Some systems define `time_t' here.  */

#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

/* 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
# define memcpy(d, s, n) bcopy (s, d, n)
#endif

#ifndef __P
#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
#define __P(args) args
#else
#define __P(args) ()
#endif  /* GCC.  */
#endif  /* Not __P.  */

#ifndef PTR
#ifdef __STDC__
#define PTR void *
#else
#define PTR char *
#endif
#endif

#ifndef CHAR_BIT
#define CHAR_BIT 8
#endif

#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


#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;
{
  struct tm *l = gmtime (t);
  if (! l)
    return 0;
  *tp = *l;
  return tp;
}
#  endif /* ! HAVE_TM_GMTOFF */

/* 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;
{
  struct tm *l = localtime (t);
  if (! l)
    return 0;
  *tp = *l;
  return tp;
}
# endif /* ! HAVE_LOCALTIME_R */
#endif /* ! defined (_LIBC) */


#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)))

#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
tm_diff (a, b)
     const struct tm *a;
     const struct tm *b;
{
  /* 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 */



/* 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);
}


#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

/* 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 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);

  const char *alt_digits = _NL_CURRENT (LC_TIME, ALT_DIGITS);
  const char *end_alt_digits = _NL_CURRENT (LC_TIME, ALT_DIGITS + 1);
#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;

  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;

  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;

	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;

	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;

	    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));

	    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 */

      /* Check for flags that can modify a number format.  */
      ++f;
      switch (*f)
	{
	case '_':
	case '-':
	  pad = *f++;
	  break;

	default:
	  pad = 0;
	  break;
	}

      /* 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

	case '\0':		/* GNU extension: % at end of format.  */
	    --f;
	    /* Fall through.  */
	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;

	case 'b':
	case 'h':		/* POSIX.2 extension.  */
	  if (modifier != 0)
	    goto bad_format;
	  cpy (am_len, a_month);
	  break;

	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 %Z %Y";
#endif

	subformat:
	  {
	    size_t len = strftime (p, maxsize - i, subfmt, tp);
	    if (len == 0 && *subfmt)
	      return 0;
	    add (len, ;);
	  }
	  break;

	case 'C':		/* POSIX.2 extension.  */
	  if (modifier == 'O')
	    goto bad_format;
#ifdef _NL_CURRENT
	  /* XXX %EC is not implemented yet.  */
#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);

	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)
	    {
	      /* ALT_DIGITS is the first entry in an array with
		 alternative digit symbols.  We have to find string
		 number NUMBER_VALUE, but must not look beyond
		 END_ALT_DIGITS.  */
	      int run = number_value;
	      const char *cp = alt_digits;

	      while (run-- > 0 && cp < end_alt_digits)
		cp = strchr (cp, '\0') + 1;

	      if (cp < end_alt_digits)
		{
		  size_t digitlen = strlen (cp);
		  if (digitlen != 0)
		    {
		      cpy (digitlen, cp);
		      break;
		    }
		}
	    }
#endif
	  {
	    unsigned int u = number_value;

	    bufp = buf + sizeof (buf);
	    negative_number = number_value < 0;

	    if (negative_number)
	      u = -u;

	    do
	      *--bufp = u % 10 + '0';
	    while ((u /= 10) != 0);
  	  }

	do_number_sign_and_padding:
	  if (negative_number)
	    *--bufp = '-';

	  if (pad != '-')
	    {
	      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);

	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 = *tp;
	    time_t 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 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;
	  }

	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);
	      }
	  }

	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':
#ifdef _NL_CURRENT
	  if (modifier == 'E'
	      && *(subfmt = _NL_CURRENT (LC_TIME, ERA_YEAR)) != '\0')
	    goto subformat;
#endif
	  if (modifier == 'O')
	    goto bad_format;
	  else
	    DO_NUMBER (1, tp->tm_year + TM_YEAR_BASE);

	case 'y':
#ifdef _NL_CURRENT
	  /* XXX %Ey is not implemented yet.  */
#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 = *tp;
	    time_t lt = mktime (&ltm);

	    if (lt == (time_t) -1)
	      {
		/* 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;

	    diff = tm_diff (&ltm, &gtm);
#endif

	    if (diff < 0)
	      {
		add (1, *p = '-');
		diff = -diff;
	      }
	    else
	      add (1, *p = '+');

	    diff /= 60;
	    DO_NUMBER (4, (diff / 60) * 100 + diff % 60);
	  }

	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 = 2; f[1 - flen] != '%'; flen++)
	      continue;
	    cpy (flen, &f[1 - flen]);
	  }
	  break;
	}
    }

  if (p)
    *p = '\0';
  return i;
}