xref: /netbsd-src/lib/libc/time/strftime.c (revision ae082add65442546470c0ba499a860ee89eed305)
1 /*	$NetBSD: strftime.c,v 1.50 2022/08/16 10:56:21 christos Exp $	*/
2 
3 /* Convert a broken-down timestamp to a string.  */
4 
5 /* Copyright 1989 The Regents of the University of California.
6    All rights reserved.
7 
8    Redistribution and use in source and binary forms, with or without
9    modification, are permitted provided that the following conditions
10    are met:
11    1. Redistributions of source code must retain the above copyright
12       notice, this list of conditions and the following disclaimer.
13    2. Redistributions in binary form must reproduce the above copyright
14       notice, this list of conditions and the following disclaimer in the
15       documentation and/or other materials provided with the distribution.
16    3. Neither the name of the University nor the names of its contributors
17       may be used to endorse or promote products derived from this software
18       without specific prior written permission.
19 
20    THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
21    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23    ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26    OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30    SUCH DAMAGE.  */
31 
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 #if 0
35 static char	elsieid[] = "@(#)strftime.c	7.64";
36 static char	elsieid[] = "@(#)strftime.c	8.3";
37 #else
38 __RCSID("$NetBSD: strftime.c,v 1.50 2022/08/16 10:56:21 christos Exp $");
39 #endif
40 #endif /* LIBC_SCCS and not lint */
41 
42 #include "namespace.h"
43 
44 #include <stddef.h>
45 #include <assert.h>
46 #include <locale.h>
47 #include "setlocale_local.h"
48 
49 /*
50 ** Based on the UCB version with the copyright notice appearing above.
51 **
52 ** This is ANSIish only when "multibyte character == plain character".
53 */
54 
55 #include "private.h"
56 
57 /*
58 ** We don't use these extensions in strftime operation even when
59 ** supported by the local tzcode configuration.  A strictly
60 ** conforming C application may leave them in undefined state.
61 */
62 
63 #ifdef _LIBC
64 #undef TM_ZONE
65 #undef TM_GMTOFF
66 #endif
67 
68 #include <fcntl.h>
69 #include <locale.h>
70 #include <stdio.h>
71 
72 #ifndef DEPRECATE_TWO_DIGIT_YEARS
73 # define DEPRECATE_TWO_DIGIT_YEARS false
74 #endif
75 
76 #ifdef __weak_alias
77 __weak_alias(strftime_l, _strftime_l)
78 __weak_alias(strftime_lz, _strftime_lz)
79 __weak_alias(strftime_z, _strftime_z)
80 #endif
81 
82 #include "sys/localedef.h"
83 #define _TIME_LOCALE(loc) \
84     ((_TimeLocale *)((loc)->part_impl[(size_t)LC_TIME]))
85 #define c_fmt   d_t_fmt
86 
87 enum warn { IN_NONE, IN_SOME, IN_THIS, IN_ALL };
88 
89 static char *	_add(const char *, char *, const char *);
90 static char *	_conv(int, const char *, char *, const char *, locale_t);
91 static char *	_fmt(const timezone_t, const char *, const struct tm *, char *,
92 			const char *, enum warn *, locale_t);
93 static char *	_yconv(int, int, bool, bool, char *, const char *, locale_t);
94 
95 #ifndef YEAR_2000_NAME
96 # define YEAR_2000_NAME "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
97 #endif /* !defined YEAR_2000_NAME */
98 
99 #define	IN_NONE	0
100 #define	IN_SOME	1
101 #define	IN_THIS	2
102 #define	IN_ALL	3
103 
104 #define	PAD_DEFAULT	0
105 #define	PAD_LESS	1
106 #define	PAD_SPACE	2
107 #define	PAD_ZERO	3
108 
109 static const char fmt_padding[][4][5] = {
110 	/* DEFAULT,	LESS,	SPACE,	ZERO */
111 #define	PAD_FMT_MONTHDAY	0
112 #define	PAD_FMT_HMS		0
113 #define	PAD_FMT_CENTURY		0
114 #define	PAD_FMT_SHORTYEAR	0
115 #define	PAD_FMT_MONTH		0
116 #define	PAD_FMT_WEEKOFYEAR	0
117 #define	PAD_FMT_DAYOFMONTH	0
118 	{ "%02d",	"%d",	"%2d",	"%02d" },
119 #define	PAD_FMT_SDAYOFMONTH	1
120 #define	PAD_FMT_SHMS		1
121 	{ "%2d",	"%d",	"%2d",	"%02d" },
122 #define	PAD_FMT_DAYOFYEAR	2
123 	{ "%03d",	"%d",	"%3d",	"%03d" },
124 #define	PAD_FMT_YEAR		3
125 	{ "%04d",	"%d",	"%4d",	"%04d" }
126 };
127 
128 size_t
129 strftime_z(const timezone_t sp, char * __restrict s, size_t maxsize,
130     const char * __restrict format, const struct tm * __restrict t)
131 {
132 	return strftime_lz(sp, s, maxsize, format, t, _current_locale());
133 }
134 
135 #if HAVE_STRFTIME_L
136 size_t
137 strftime_l(char *s, size_t maxsize, char const *format, struct tm const *t,
138 	   locale_t locale)
139 {
140   /* Just call strftime, as only the C locale is supported.  */
141   return strftime(s, maxsize, format, t);
142 }
143 #endif
144 
145 size_t
146 strftime_lz(const timezone_t sp, char *const s, const size_t maxsize,
147     const char *const format, const struct tm *const t, locale_t loc)
148 {
149 	char *	p;
150 	int saved_errno = errno;
151 	enum warn warn = IN_NONE;
152 
153 	p = _fmt(sp, format, t, s, s + maxsize, &warn, loc);
154 	if (!p) {
155 		errno = EOVERFLOW;
156 		return 0;
157 	}
158 	if (/*CONSTCOND*/DEPRECATE_TWO_DIGIT_YEARS
159 	    && warn != IN_NONE && getenv(YEAR_2000_NAME)) {
160 		(void) fprintf(stderr, "\n");
161 		(void) fprintf(stderr, "strftime format \"%s\" ", format);
162 		(void) fprintf(stderr, "yields only two digits of years in ");
163 		if (warn == IN_SOME)
164 			(void) fprintf(stderr, "some locales");
165 		else if (warn == IN_THIS)
166 			(void) fprintf(stderr, "the current locale");
167 		else	(void) fprintf(stderr, "all locales");
168 		(void) fprintf(stderr, "\n");
169 	}
170 	if (p == s + maxsize) {
171 		errno = ERANGE;
172 		return 0;
173 	}
174 	*p = '\0';
175 	errno = saved_errno;
176 	return p - s;
177 }
178 
179 static char *
180 _fmt(const timezone_t sp, const char *format, const struct tm *t, char *pt,
181      const char *ptlim, enum warn *warnp, locale_t loc)
182 {
183 	int Ealternative, Oalternative, PadIndex;
184 	_TimeLocale *tptr = _TIME_LOCALE(loc);
185 
186 	for ( ; *format; ++format) {
187 		if (*format == '%') {
188 			Ealternative = 0;
189 			Oalternative = 0;
190 			PadIndex = PAD_DEFAULT;
191 label:
192 			switch (*++format) {
193 			case '\0':
194 				--format;
195 				break;
196 			case 'A':
197 				pt = _add((t->tm_wday < 0 ||
198 					t->tm_wday >= DAYSPERWEEK) ?
199 					"?" : tptr->day[t->tm_wday],
200 					pt, ptlim);
201 				continue;
202 			case 'a':
203 				pt = _add((t->tm_wday < 0 ||
204 					t->tm_wday >= DAYSPERWEEK) ?
205 					"?" : tptr->abday[t->tm_wday],
206 					pt, ptlim);
207 				continue;
208 			case 'B':
209 				pt = _add((t->tm_mon < 0 ||
210 					t->tm_mon >= MONSPERYEAR) ?
211 					"?" :
212 					/* no alt_month in _TimeLocale */
213 					(Oalternative ? tptr->mon/*alt_month*/:
214 					tptr->mon)[t->tm_mon],
215 					pt, ptlim);
216 				continue;
217 			case 'b':
218 			case 'h':
219 				pt = _add((t->tm_mon < 0 ||
220 					t->tm_mon >= MONSPERYEAR) ?
221 					"?" : tptr->abmon[t->tm_mon],
222 					pt, ptlim);
223 				continue;
224 			case 'C':
225 				/*
226 				** %C used to do a...
227 				**	_fmt("%a %b %e %X %Y", t);
228 				** ...whereas now POSIX 1003.2 calls for
229 				** something completely different.
230 				** (ado, 1993-05-24)
231 				*/
232 				pt = _yconv(t->tm_year, TM_YEAR_BASE,
233 					    true, false, pt, ptlim, loc);
234 				continue;
235 			case 'c':
236 				{
237 				enum warn warn2 = IN_SOME;
238 
239 				pt = _fmt(sp, tptr->c_fmt, t, pt,
240 				    ptlim, &warn2, loc);
241 				if (warn2 == IN_ALL)
242 					warn2 = IN_THIS;
243 				if (warn2 > *warnp)
244 					*warnp = warn2;
245 				}
246 				continue;
247 			case 'D':
248 				pt = _fmt(sp, "%m/%d/%y", t, pt, ptlim, warnp,
249 				    loc);
250 				continue;
251 			case 'd':
252 				pt = _conv(t->tm_mday,
253 				    fmt_padding[PAD_FMT_DAYOFMONTH][PadIndex],
254 				    pt, ptlim, loc);
255 				continue;
256 			case 'E':
257 				if (Ealternative || Oalternative)
258 					break;
259 				Ealternative++;
260 				goto label;
261 			case 'O':
262 				/*
263 				** Locale modifiers of C99 and later.
264 				** The sequences
265 				**	%Ec %EC %Ex %EX %Ey %EY
266 				**	%Od %oe %OH %OI %Om %OM
267 				**	%OS %Ou %OU %OV %Ow %OW %Oy
268 				** are supposed to provide alternative
269 				** representations.
270 				*/
271 				if (Ealternative || Oalternative)
272 					break;
273 				Oalternative++;
274 				goto label;
275 			case 'e':
276 				pt = _conv(t->tm_mday,
277 				    fmt_padding[PAD_FMT_SDAYOFMONTH][PadIndex],
278 				    pt, ptlim, loc);
279 				continue;
280 			case 'F':
281 				pt = _fmt(sp, "%Y-%m-%d", t, pt, ptlim, warnp,
282 				    loc);
283 				continue;
284 			case 'H':
285 				pt = _conv(t->tm_hour,
286 				    fmt_padding[PAD_FMT_HMS][PadIndex],
287 				    pt, ptlim, loc);
288 				continue;
289 			case 'I':
290 				pt = _conv((t->tm_hour % 12) ?
291 				    (t->tm_hour % 12) : 12,
292 				    fmt_padding[PAD_FMT_HMS][PadIndex],
293 				    pt, ptlim, loc);
294 				continue;
295 			case 'j':
296 				pt = _conv(t->tm_yday + 1,
297 				    fmt_padding[PAD_FMT_DAYOFYEAR][PadIndex],
298 				    pt, ptlim, loc);
299 				continue;
300 			case 'k':
301 				/*
302 				** This used to be...
303 				**	_conv(t->tm_hour % 12 ?
304 				**		t->tm_hour % 12 : 12, 2, ' ');
305 				** ...and has been changed to the below to
306 				** match SunOS 4.1.1 and Arnold Robbins'
307 				** strftime version 3.0. That is, "%k" and
308 				** "%l" have been swapped.
309 				** (ado, 1993-05-24)
310 				*/
311 				pt = _conv(t->tm_hour,
312 				    fmt_padding[PAD_FMT_SHMS][PadIndex],
313 				    pt, ptlim, loc);
314 				continue;
315 #ifdef KITCHEN_SINK
316 			case 'K':
317 				/*
318 				** After all this time, still unclaimed!
319 				*/
320 				pt = _add("kitchen sink", pt, ptlim);
321 				continue;
322 #endif /* defined KITCHEN_SINK */
323 			case 'l':
324 				/*
325 				** This used to be...
326 				**	_conv(t->tm_hour, 2, ' ');
327 				** ...and has been changed to the below to
328 				** match SunOS 4.1.1 and Arnold Robbin's
329 				** strftime version 3.0. That is, "%k" and
330 				** "%l" have been swapped.
331 				** (ado, 1993-05-24)
332 				*/
333 				pt = _conv((t->tm_hour % 12) ?
334 					(t->tm_hour % 12) : 12,
335 					fmt_padding[PAD_FMT_SHMS][PadIndex],
336 					pt, ptlim, loc);
337 				continue;
338 			case 'M':
339 				pt = _conv(t->tm_min,
340 				    fmt_padding[PAD_FMT_HMS][PadIndex],
341 				    pt, ptlim, loc);
342 				continue;
343 			case 'm':
344 				pt = _conv(t->tm_mon + 1,
345 				    fmt_padding[PAD_FMT_MONTH][PadIndex],
346 				    pt, ptlim, loc);
347 				continue;
348 			case 'n':
349 				pt = _add("\n", pt, ptlim);
350 				continue;
351 			case 'p':
352 				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
353 					tptr->am_pm[1] :
354 					tptr->am_pm[0],
355 					pt, ptlim);
356 				continue;
357 			case 'R':
358 				pt = _fmt(sp, "%H:%M", t, pt, ptlim, warnp,
359 				    loc);
360 				continue;
361 			case 'r':
362 				pt = _fmt(sp, tptr->t_fmt_ampm, t,
363 				    pt, ptlim, warnp, loc);
364 				continue;
365 			case 'S':
366 				pt = _conv(t->tm_sec,
367 				    fmt_padding[PAD_FMT_HMS][PadIndex],
368 				    pt, ptlim, loc);
369 				continue;
370 			case 's':
371 				{
372 					struct tm	tm;
373 					char		buf[INT_STRLEN_MAXIMUM(
374 								time_t) + 1];
375 					time_t		mkt;
376 
377 					tm = *t;
378 					mkt = mktime_z(sp, &tm);
379 					/* There is no portable, definitive
380 					   test for whether whether mktime
381 					   succeeded, so treat (time_t) -1 as
382 					   the success that it might be.  */
383 					/* CONSTCOND */
384 					if (TYPE_SIGNED(time_t)) {
385 						intmax_t n = mkt;
386 						(void)snprintf(buf, sizeof(buf),
387 						    "%"PRIdMAX, n);
388 					} else {
389 						uintmax_t n = mkt;
390 						(void)snprintf(buf, sizeof(buf),
391 						    "%"PRIuMAX, n);
392 					}
393 					pt = _add(buf, pt, ptlim);
394 				}
395 				continue;
396 			case 'T':
397 				pt = _fmt(sp, "%H:%M:%S", t, pt, ptlim, warnp,
398 				    loc);
399 				continue;
400 			case 't':
401 				pt = _add("\t", pt, ptlim);
402 				continue;
403 			case 'U':
404 				pt = _conv((t->tm_yday + DAYSPERWEEK -
405 				    t->tm_wday) / DAYSPERWEEK,
406 				    fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex],
407 				    pt, ptlim, loc);
408 				continue;
409 			case 'u':
410 				/*
411 				** From Arnold Robbins' strftime version 3.0:
412 				** "ISO 8601: Weekday as a decimal number
413 				** [1 (Monday) - 7]"
414 				** (ado, 1993-05-24)
415 				*/
416 				pt = _conv((t->tm_wday == 0) ?
417 					DAYSPERWEEK : t->tm_wday,
418 					"%d", pt, ptlim, loc);
419 				continue;
420 			case 'V':	/* ISO 8601 week number */
421 			case 'G':	/* ISO 8601 year (four digits) */
422 			case 'g':	/* ISO 8601 year (two digits) */
423 /*
424 ** From Arnold Robbins' strftime version 3.0: "the week number of the
425 ** year (the first Monday as the first day of week 1) as a decimal number
426 ** (01-53)."
427 ** (ado, 1993-05-24)
428 **
429 ** From <https://www.cl.cam.ac.uk/~mgk25/iso-time.html> by Markus Kuhn:
430 ** "Week 01 of a year is per definition the first week which has the
431 ** Thursday in this year, which is equivalent to the week which contains
432 ** the fourth day of January. In other words, the first week of a new year
433 ** is the week which has the majority of its days in the new year. Week 01
434 ** might also contain days from the previous year and the week before week
435 ** 01 of a year is the last week (52 or 53) of the previous year even if
436 ** it contains days from the new year. A week starts with Monday (day 1)
437 ** and ends with Sunday (day 7). For example, the first week of the year
438 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
439 ** (ado, 1996-01-02)
440 */
441 				{
442 					int	year;
443 					int	base;
444 					int	yday;
445 					int	wday;
446 					int	w;
447 
448 					year = t->tm_year;
449 					base = TM_YEAR_BASE;
450 					yday = t->tm_yday;
451 					wday = t->tm_wday;
452 					for ( ; ; ) {
453 						int	len;
454 						int	bot;
455 						int	top;
456 
457 						len = isleap_sum(year, base) ?
458 							DAYSPERLYEAR :
459 							DAYSPERNYEAR;
460 						/*
461 						** What yday (-3 ... 3) does
462 						** the ISO year begin on?
463 						*/
464 						bot = ((yday + 11 - wday) %
465 							DAYSPERWEEK) - 3;
466 						/*
467 						** What yday does the NEXT
468 						** ISO year begin on?
469 						*/
470 						top = bot -
471 							(len % DAYSPERWEEK);
472 						if (top < -3)
473 							top += DAYSPERWEEK;
474 						top += len;
475 						if (yday >= top) {
476 							++base;
477 							w = 1;
478 							break;
479 						}
480 						if (yday >= bot) {
481 							w = 1 + ((yday - bot) /
482 								DAYSPERWEEK);
483 							break;
484 						}
485 						--base;
486 						yday += isleap_sum(year, base) ?
487 							DAYSPERLYEAR :
488 							DAYSPERNYEAR;
489 					}
490 #ifdef XPG4_1994_04_09
491 					if ((w == 52 &&
492 						t->tm_mon == TM_JANUARY) ||
493 						(w == 1 &&
494 						t->tm_mon == TM_DECEMBER))
495 							w = 53;
496 #endif /* defined XPG4_1994_04_09 */
497 					if (*format == 'V')
498 						pt = _conv(w,
499 						    fmt_padding[
500 						    PAD_FMT_WEEKOFYEAR][
501 						    PadIndex], pt, ptlim, loc);
502 					else if (*format == 'g') {
503 						*warnp = IN_ALL;
504 						pt = _yconv(year, base,
505 							false, true,
506 							pt, ptlim, loc);
507 					} else	pt = _yconv(year, base,
508 							true, true,
509 							pt, ptlim, loc);
510 				}
511 				continue;
512 			case 'v':
513 				/*
514 				** From Arnold Robbins' strftime version 3.0:
515 				** "date as dd-bbb-YYYY"
516 				** (ado, 1993-05-24)
517 				*/
518 				pt = _fmt(sp, "%e-%b-%Y", t, pt, ptlim, warnp,
519 				    loc);
520 				continue;
521 			case 'W':
522 				pt = _conv((t->tm_yday + DAYSPERWEEK -
523 				    (t->tm_wday ?
524 				    (t->tm_wday - 1) :
525 				    (DAYSPERWEEK - 1))) / DAYSPERWEEK,
526 				    fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex],
527 				    pt, ptlim, loc);
528 				continue;
529 			case 'w':
530 				pt = _conv(t->tm_wday, "%d", pt, ptlim, loc);
531 				continue;
532 			case 'X':
533 				pt = _fmt(sp, tptr->t_fmt, t, pt,
534 				    ptlim, warnp, loc);
535 				continue;
536 			case 'x':
537 				{
538 				enum warn warn2 = IN_SOME;
539 
540 				pt = _fmt(sp, tptr->d_fmt, t, pt,
541 				    ptlim, &warn2, loc);
542 				if (warn2 == IN_ALL)
543 					warn2 = IN_THIS;
544 				if (warn2 > *warnp)
545 					*warnp = warn2;
546 				}
547 				continue;
548 			case 'y':
549 				*warnp = IN_ALL;
550 				pt = _yconv(t->tm_year, TM_YEAR_BASE,
551 					false, true,
552 					pt, ptlim, loc);
553 				continue;
554 			case 'Y':
555 				pt = _yconv(t->tm_year, TM_YEAR_BASE,
556 					true, true,
557 					pt, ptlim, loc);
558 				continue;
559 			case 'Z':
560 #ifdef TM_ZONE
561 				pt = _add(t->TM_ZONE, pt, ptlim);
562 #elif HAVE_TZNAME
563 				if (t->tm_isdst >= 0) {
564 					int oerrno = errno, dst = t->tm_isdst;
565 					const char *z =
566 					    tzgetname(sp, dst);
567 					if (z == NULL)
568 						z = tzgetname(sp, !dst);
569 					if (z != NULL)
570 						pt = _add(z, pt, ptlim);
571 					errno = oerrno;
572 				}
573 #endif
574 				/*
575 				** C99 and later say that %Z must be
576 				** replaced by the empty string if the
577 				** time zone abbreviation is not
578 				** determinable.
579 				*/
580 				continue;
581 			case 'z':
582 #if defined TM_GMTOFF || USG_COMPAT || ALTZONE
583 				{
584 				long		diff;
585 				char const *	sign;
586 				bool negative;
587 
588 				if (t->tm_isdst < 0)
589 					continue;
590 # ifdef TM_GMTOFF
591 				diff = (int)t->TM_GMTOFF;
592 # else
593 				/*
594 				** C99 and later say that the UT offset must
595 				** be computed by looking only at
596 				** tm_isdst. This requirement is
597 				** incorrect, since it means the code
598 				** must rely on magic (in this case
599 				** altzone and timezone), and the
600 				** magic might not have the correct
601 				** offset. Doing things correctly is
602 				** tricky and requires disobeying the standard;
603 				** see GNU C strftime for details.
604 				** For now, punt and conform to the
605 				** standard, even though it's incorrect.
606 				**
607 				** C99 and later say that %z must be replaced by
608 				** the empty string if the time zone is not
609 				** determinable, so output nothing if the
610 				** appropriate variables are not available.
611 				*/
612 #  ifndef STD_INSPIRED
613 				if (t->tm_isdst == 0)
614 #   if USG_COMPAT
615 					diff = -timezone;
616 #   else
617 					continue;
618 #   endif
619 				else
620 #   if ALTZONE
621 					diff = -altzone;
622 #   else
623 					continue;
624 #   endif
625 #  else
626 				{
627 					struct tm tmp;
628 					time_t lct, gct;
629 
630 					/*
631 					** Get calendar time from t
632 					** being treated as local.
633 					*/
634 					tmp = *t; /* mktime discards const */
635 					lct = mktime_z(sp, &tmp);
636 
637 					if (lct == (time_t)-1)
638 						continue;
639 
640 					/*
641 					** Get calendar time from t
642 					** being treated as GMT.
643 					**/
644 					tmp = *t; /* mktime discards const */
645 					gct = timegm(&tmp);
646 
647 					if (gct == (time_t)-1)
648 						continue;
649 
650 					/* LINTED difference will fit int */
651 					diff = (intmax_t)gct - (intmax_t)lct;
652 				}
653 #  endif
654 # endif
655 				negative = diff < 0;
656 				if (diff == 0) {
657 # ifdef TM_ZONE
658 				  negative = t->TM_ZONE[0] == '-';
659 # else
660 				  negative = t->tm_isdst < 0;
661 #  if HAVE_TZNAME
662 				  if (tzname[t->tm_isdst != 0][0] == '-')
663 				    negative = true;
664 #  endif
665 # endif
666 				}
667 				if (negative) {
668 					sign = "-";
669 					diff = -diff;
670 				} else	sign = "+";
671 				pt = _add(sign, pt, ptlim);
672 				diff /= SECSPERMIN;
673 				diff = (diff / MINSPERHOUR) * 100 +
674 					(diff % MINSPERHOUR);
675 				_DIAGASSERT(__type_fit(int, diff));
676 				pt = _conv((int)diff,
677 				    fmt_padding[PAD_FMT_YEAR][PadIndex],
678 				    pt, ptlim, loc);
679 				}
680 #endif
681 				continue;
682 			case '+':
683 #ifdef notyet
684 				/* XXX: no date_fmt in _TimeLocale */
685 				pt = _fmt(sp, tptr->date_fmt, t,
686 				    pt, ptlim, warnp, loc);
687 #else
688 				pt = _fmt(sp, "%a %b %e %H:%M:%S %Z %Y", t,
689 				    pt, ptlim, warnp, loc);
690 #endif
691 				continue;
692 			case '-':
693 				if (PadIndex != PAD_DEFAULT)
694 					break;
695 				PadIndex = PAD_LESS;
696 				goto label;
697 			case '_':
698 				if (PadIndex != PAD_DEFAULT)
699 					break;
700 				PadIndex = PAD_SPACE;
701 				goto label;
702 			case '0':
703 				if (PadIndex != PAD_DEFAULT)
704 					break;
705 				PadIndex = PAD_ZERO;
706 				goto label;
707 			case '%':
708 			/*
709 			** X311J/88-090 (4.12.3.5): if conversion char is
710 			** undefined, behavior is undefined. Print out the
711 			** character itself as printf(3) also does.
712 			*/
713 			default:
714 				break;
715 			}
716 		}
717 		if (pt == ptlim)
718 			break;
719 		*pt++ = *format;
720 	}
721 	return pt;
722 }
723 
724 size_t
725 strftime(char *s, size_t maxsize, const char *format, const struct tm *t)
726 {
727 	size_t r;
728 
729 	rwlock_wrlock(&__lcl_lock);
730 	tzset_unlocked();
731 	r = strftime_z(__lclptr, s, maxsize, format, t);
732 	rwlock_unlock(&__lcl_lock);
733 
734 	return r;
735 }
736 
737 size_t
738 strftime_l(char * __restrict s, size_t maxsize, const char * __restrict format,
739     const struct tm * __restrict t, locale_t loc)
740 {
741 	size_t r;
742 
743 	rwlock_wrlock(&__lcl_lock);
744 	tzset_unlocked();
745 	r = strftime_lz(__lclptr, s, maxsize, format, t, loc);
746 	rwlock_unlock(&__lcl_lock);
747 
748 	return r;
749 }
750 
751 static char *
752 _conv(int n, const char *format, char *pt, const char *ptlim, locale_t loc)
753 {
754 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
755 
756 	(void) snprintf_l(buf, sizeof(buf), loc, format, n);
757 	return _add(buf, pt, ptlim);
758 }
759 
760 static char *
761 _add(const char *str, char *pt, const char *ptlim)
762 {
763 	while (pt < ptlim && (*pt = *str++) != '\0')
764 		++pt;
765 	return pt;
766 }
767 
768 /*
769 ** POSIX and the C Standard are unclear or inconsistent about
770 ** what %C and %y do if the year is negative or exceeds 9999.
771 ** Use the convention that %C concatenated with %y yields the
772 ** same output as %Y, and that %Y contains at least 4 bytes,
773 ** with more only if necessary.
774 */
775 
776 static char *
777 _yconv(int a, int b, bool convert_top, bool convert_yy,
778     char *pt, const char * ptlim, locale_t loc)
779 {
780 	int	lead;
781 	int	trail;
782 
783 	int DIVISOR = 100;
784 	trail = a % DIVISOR + b % DIVISOR;
785 	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
786 	trail %= DIVISOR;
787 	if (trail < 0 && lead > 0) {
788 		trail += DIVISOR;
789 		--lead;
790 	} else if (lead < 0 && trail > 0) {
791 		trail -= DIVISOR;
792 		++lead;
793 	}
794 	if (convert_top) {
795 		if (lead == 0 && trail < 0)
796 			pt = _add("-0", pt, ptlim);
797 		else	pt = _conv(lead, "%02d", pt, ptlim, loc);
798 	}
799 	if (convert_yy)
800 		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim,
801 		    loc);
802 	return pt;
803 }
804