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strftime.c revision 1.26
      1 /*	$NetBSD: strftime.c,v 1.26 2013/05/17 12:55:57 joerg Exp $	*/
      2 
      3 #include <sys/cdefs.h>
      4 #if defined(LIBC_SCCS) && !defined(lint)
      5 #if 0
      6 static char	elsieid[] = "@(#)strftime.c	7.64";
      7 static char	elsieid[] = "@(#)strftime.c	8.3";
      8 #else
      9 __RCSID("$NetBSD: strftime.c,v 1.26 2013/05/17 12:55:57 joerg Exp $");
     10 #endif
     11 #endif /* LIBC_SCCS and not lint */
     12 
     13 #include "namespace.h"
     14 
     15 #include <stddef.h>
     16 #include <locale.h>
     17 #include "setlocale_local.h"
     18 
     19 /*
     20 ** Based on the UCB version with the copyright notice and sccsid
     21 ** appearing below.
     22 **
     23 ** This is ANSIish only when "multibyte character == plain character".
     24 */
     25 
     26 #include "private.h"
     27 
     28 /*
     29 ** We don't use these extensions in strftime operation even when
     30 ** supported by the local tzcode configuration.  A strictly
     31 ** conforming C application may leave them in undefined state.
     32 */
     33 
     34 #ifdef _LIBC
     35 #undef TM_ZONE
     36 #undef TM_GMTOFF
     37 #endif
     38 
     39 /*
     40 ** Copyright (c) 1989, 1993
     41 **	The Regents of the University of California.  All rights reserved.
     42 **
     43 ** Redistribution and use in source and binary forms, with or without
     44 ** modification, are permitted provided that the following conditions
     45 ** are met:
     46 ** 1. Redistributions of source code must retain the above copyright
     47 **    notice, this list of conditions and the following disclaimer.
     48 ** 2. Redistributions in binary form must reproduce the above copyright
     49 **    notice, this list of conditions and the following disclaimer in the
     50 **    documentation and/or other materials provided with the distribution.
     51 ** 3. All advertising materials mentioning features or use of this software
     52 **    must display the following acknowledgement:
     53 **	This product includes software developed by the University of
     54 **	California, Berkeley and its contributors.
     55 ** 4. Neither the name of the University nor the names of its contributors
     56 **    may be used to endorse or promote products derived from this software
     57 **    without specific prior written permission.
     58 **
     59 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     60 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     61 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     62 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     63 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     64 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     65 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     66 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     67 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     68 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     69 ** SUCH DAMAGE.
     70 */
     71 
     72 #ifndef LIBC_SCCS
     73 #ifndef lint
     74 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
     75 #endif /* !defined lint */
     76 #endif /* !defined LIBC_SCCS */
     77 
     78 #include "tzfile.h"
     79 #include "fcntl.h"
     80 #include "locale.h"
     81 
     82 #ifdef __weak_alias
     83 __weak_alias(strftime_l, _strftime_l)
     84 __weak_alias(strftime_lz, _strftime_lz)
     85 __weak_alias(strftime_z, _strftime_z)
     86 #endif
     87 
     88 #include "sys/localedef.h"
     89 #define _TIME_LOCALE(loc) \
     90     ((_TimeLocale *)((loc)->part_impl[(size_t)LC_TIME]))
     91 #define c_fmt   d_t_fmt
     92 
     93 static char *	_add(const char *, char *, const char *);
     94 static char *	_conv(int, const char *, char *, const char *);
     95 static char *	_fmt(const timezone_t, const char *, const struct tm *, char *,
     96 			const char *, int *, locale_t);
     97 static char *	_yconv(int, int, int, int, char *, const char *);
     98 
     99 extern char *	tzname[];
    100 
    101 #ifndef YEAR_2000_NAME
    102 #define YEAR_2000_NAME	"CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
    103 #endif /* !defined YEAR_2000_NAME */
    104 
    105 #define IN_NONE	0
    106 #define IN_SOME	1
    107 #define IN_THIS	2
    108 #define IN_ALL	3
    109 
    110 size_t
    111 strftime_z(const timezone_t sp, char * __restrict s, size_t maxsize,
    112     const char * __restrict format, const struct tm * __restrict t)
    113 {
    114 	return strftime_lz(sp, s, maxsize, format, t, _current_locale());
    115 }
    116 
    117 size_t
    118 strftime_lz(const timezone_t sp, char *const s, const size_t maxsize,
    119     const char *const format, const struct tm *const t, locale_t loc)
    120 {
    121 	char *	p;
    122 	int	warn;
    123 
    124 	warn = IN_NONE;
    125 	p = _fmt(sp, ((format == NULL) ? "%c" : format), t, s, s + maxsize,
    126 	    &warn, loc);
    127 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
    128 	if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
    129 		(void) fprintf(stderr, "\n");
    130 		if (format == NULL)
    131 			(void) fprintf(stderr, "NULL strftime format ");
    132 		else	(void) fprintf(stderr, "strftime format \"%s\" ",
    133 				format);
    134 		(void) fprintf(stderr, "yields only two digits of years in ");
    135 		if (warn == IN_SOME)
    136 			(void) fprintf(stderr, "some locales");
    137 		else if (warn == IN_THIS)
    138 			(void) fprintf(stderr, "the current locale");
    139 		else	(void) fprintf(stderr, "all locales");
    140 		(void) fprintf(stderr, "\n");
    141 	}
    142 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
    143 	if (p == s + maxsize)
    144 		return 0;
    145 	*p = '\0';
    146 	return p - s;
    147 }
    148 
    149 static char *
    150 _fmt(const timezone_t sp, const char *format, const struct tm *const t,
    151 	char *pt, const char *const ptlim, int *warnp, locale_t loc)
    152 {
    153 	for ( ; *format; ++format) {
    154 		if (*format == '%') {
    155 label:
    156 			switch (*++format) {
    157 			case '\0':
    158 				--format;
    159 				break;
    160 			case 'A':
    161 				pt = _add((t->tm_wday < 0 ||
    162 					t->tm_wday >= DAYSPERWEEK) ?
    163 					"?" : _TIME_LOCALE(loc)->day[t->tm_wday],
    164 					pt, ptlim);
    165 				continue;
    166 			case 'a':
    167 				pt = _add((t->tm_wday < 0 ||
    168 					t->tm_wday >= DAYSPERWEEK) ?
    169 					"?" : _TIME_LOCALE(loc)->abday[t->tm_wday],
    170 					pt, ptlim);
    171 				continue;
    172 			case 'B':
    173 				pt = _add((t->tm_mon < 0 ||
    174 					t->tm_mon >= MONSPERYEAR) ?
    175 					"?" : _TIME_LOCALE(loc)->mon[t->tm_mon],
    176 					pt, ptlim);
    177 				continue;
    178 			case 'b':
    179 			case 'h':
    180 				pt = _add((t->tm_mon < 0 ||
    181 					t->tm_mon >= MONSPERYEAR) ?
    182 					"?" : _TIME_LOCALE(loc)->abmon[t->tm_mon],
    183 					pt, ptlim);
    184 				continue;
    185 			case 'C':
    186 				/*
    187 				** %C used to do a...
    188 				**	_fmt("%a %b %e %X %Y", t);
    189 				** ...whereas now POSIX 1003.2 calls for
    190 				** something completely different.
    191 				** (ado, 1993-05-24)
    192 				*/
    193 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
    194 					pt, ptlim);
    195 				continue;
    196 			case 'c':
    197 				{
    198 				int warn2 = IN_SOME;
    199 
    200 				pt = _fmt(sp, _TIME_LOCALE(loc)->c_fmt, t, pt,
    201 				    ptlim, &warn2, loc);
    202 				if (warn2 == IN_ALL)
    203 					warn2 = IN_THIS;
    204 				if (warn2 > *warnp)
    205 					*warnp = warn2;
    206 				}
    207 				continue;
    208 			case 'D':
    209 				pt = _fmt(sp, "%m/%d/%y", t, pt, ptlim, warnp,
    210 				    loc);
    211 				continue;
    212 			case 'd':
    213 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
    214 				continue;
    215 			case 'E':
    216 			case 'O':
    217 				/*
    218 				** C99 locale modifiers.
    219 				** The sequences
    220 				**	%Ec %EC %Ex %EX %Ey %EY
    221 				**	%Od %oe %OH %OI %Om %OM
    222 				**	%OS %Ou %OU %OV %Ow %OW %Oy
    223 				** are supposed to provide alternate
    224 				** representations.
    225 				*/
    226 				goto label;
    227 			case 'e':
    228 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
    229 				continue;
    230 			case 'F':
    231 				pt = _fmt(sp, "%Y-%m-%d", t, pt, ptlim, warnp,
    232 				    loc);
    233 				continue;
    234 			case 'H':
    235 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
    236 				continue;
    237 			case 'I':
    238 				pt = _conv((t->tm_hour % 12) ?
    239 					(t->tm_hour % 12) : 12,
    240 					"%02d", pt, ptlim);
    241 				continue;
    242 			case 'j':
    243 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
    244 				continue;
    245 			case 'k':
    246 				/*
    247 				** This used to be...
    248 				**	_conv(t->tm_hour % 12 ?
    249 				**		t->tm_hour % 12 : 12, 2, ' ');
    250 				** ...and has been changed to the below to
    251 				** match SunOS 4.1.1 and Arnold Robbins'
    252 				** strftime version 3.0. That is, "%k" and
    253 				** "%l" have been swapped.
    254 				** (ado, 1993-05-24)
    255 				*/
    256 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
    257 				continue;
    258 #ifdef KITCHEN_SINK
    259 			case 'K':
    260 				/*
    261 				** After all this time, still unclaimed!
    262 				*/
    263 				pt = _add("kitchen sink", pt, ptlim);
    264 				continue;
    265 #endif /* defined KITCHEN_SINK */
    266 			case 'l':
    267 				/*
    268 				** This used to be...
    269 				**	_conv(t->tm_hour, 2, ' ');
    270 				** ...and has been changed to the below to
    271 				** match SunOS 4.1.1 and Arnold Robbin's
    272 				** strftime version 3.0. That is, "%k" and
    273 				** "%l" have been swapped.
    274 				** (ado, 1993-05-24)
    275 				*/
    276 				pt = _conv((t->tm_hour % 12) ?
    277 					(t->tm_hour % 12) : 12,
    278 					"%2d", pt, ptlim);
    279 				continue;
    280 			case 'M':
    281 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
    282 				continue;
    283 			case 'm':
    284 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
    285 				continue;
    286 			case 'n':
    287 				pt = _add("\n", pt, ptlim);
    288 				continue;
    289 			case 'p':
    290 				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
    291 					_TIME_LOCALE(loc)->am_pm[1] :
    292 					_TIME_LOCALE(loc)->am_pm[0],
    293 					pt, ptlim);
    294 				continue;
    295 			case 'R':
    296 				pt = _fmt(sp, "%H:%M", t, pt, ptlim, warnp,
    297 				    loc);
    298 				continue;
    299 			case 'r':
    300 				pt = _fmt(sp, _TIME_LOCALE(loc)->t_fmt_ampm, t,
    301 				    pt, ptlim, warnp, loc);
    302 				continue;
    303 			case 'S':
    304 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
    305 				continue;
    306 			case 's':
    307 				{
    308 					struct tm	tm;
    309 					char		buf[INT_STRLEN_MAXIMUM(
    310 								time_t) + 1];
    311 					time_t		mkt;
    312 
    313 					tm = *t;
    314 					mkt = mktime(&tm);
    315 					/* CONSTCOND */
    316 					if (TYPE_SIGNED(time_t))
    317 						(void) snprintf(buf, sizeof(buf),
    318 						    "%lld", (long long) mkt);
    319 					else	(void) snprintf(buf, sizeof(buf),
    320 						    "%llu", (unsigned long long)
    321 						    mkt);
    322 					pt = _add(buf, pt, ptlim);
    323 				}
    324 				continue;
    325 			case 'T':
    326 				pt = _fmt(sp, "%H:%M:%S", t, pt, ptlim, warnp,
    327 				    loc);
    328 				continue;
    329 			case 't':
    330 				pt = _add("\t", pt, ptlim);
    331 				continue;
    332 			case 'U':
    333 				pt = _conv((t->tm_yday + DAYSPERWEEK -
    334 					t->tm_wday) / DAYSPERWEEK,
    335 					"%02d", pt, ptlim);
    336 				continue;
    337 			case 'u':
    338 				/*
    339 				** From Arnold Robbins' strftime version 3.0:
    340 				** "ISO 8601: Weekday as a decimal number
    341 				** [1 (Monday) - 7]"
    342 				** (ado, 1993-05-24)
    343 				*/
    344 				pt = _conv((t->tm_wday == 0) ?
    345 					DAYSPERWEEK : t->tm_wday,
    346 					"%d", pt, ptlim);
    347 				continue;
    348 			case 'V':	/* ISO 8601 week number */
    349 			case 'G':	/* ISO 8601 year (four digits) */
    350 			case 'g':	/* ISO 8601 year (two digits) */
    351 /*
    352 ** From Arnold Robbins' strftime version 3.0: "the week number of the
    353 ** year (the first Monday as the first day of week 1) as a decimal number
    354 ** (01-53)."
    355 ** (ado, 1993-05-24)
    356 **
    357 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
    358 ** "Week 01 of a year is per definition the first week which has the
    359 ** Thursday in this year, which is equivalent to the week which contains
    360 ** the fourth day of January. In other words, the first week of a new year
    361 ** is the week which has the majority of its days in the new year. Week 01
    362 ** might also contain days from the previous year and the week before week
    363 ** 01 of a year is the last week (52 or 53) of the previous year even if
    364 ** it contains days from the new year. A week starts with Monday (day 1)
    365 ** and ends with Sunday (day 7). For example, the first week of the year
    366 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
    367 ** (ado, 1996-01-02)
    368 */
    369 				{
    370 					int	year;
    371 					int	base;
    372 					int	yday;
    373 					int	wday;
    374 					int	w;
    375 
    376 					year = t->tm_year;
    377 					base = TM_YEAR_BASE;
    378 					yday = t->tm_yday;
    379 					wday = t->tm_wday;
    380 					for ( ; ; ) {
    381 						int	len;
    382 						int	bot;
    383 						int	top;
    384 
    385 						len = isleap_sum(year, base) ?
    386 							DAYSPERLYEAR :
    387 							DAYSPERNYEAR;
    388 						/*
    389 						** What yday (-3 ... 3) does
    390 						** the ISO year begin on?
    391 						*/
    392 						bot = ((yday + 11 - wday) %
    393 							DAYSPERWEEK) - 3;
    394 						/*
    395 						** What yday does the NEXT
    396 						** ISO year begin on?
    397 						*/
    398 						top = bot -
    399 							(len % DAYSPERWEEK);
    400 						if (top < -3)
    401 							top += DAYSPERWEEK;
    402 						top += len;
    403 						if (yday >= top) {
    404 							++base;
    405 							w = 1;
    406 							break;
    407 						}
    408 						if (yday >= bot) {
    409 							w = 1 + ((yday - bot) /
    410 								DAYSPERWEEK);
    411 							break;
    412 						}
    413 						--base;
    414 						yday += isleap_sum(year, base) ?
    415 							DAYSPERLYEAR :
    416 							DAYSPERNYEAR;
    417 					}
    418 #ifdef XPG4_1994_04_09
    419 					if ((w == 52 &&
    420 						t->tm_mon == TM_JANUARY) ||
    421 						(w == 1 &&
    422 						t->tm_mon == TM_DECEMBER))
    423 							w = 53;
    424 #endif /* defined XPG4_1994_04_09 */
    425 					if (*format == 'V')
    426 						pt = _conv(w, "%02d",
    427 							pt, ptlim);
    428 					else if (*format == 'g') {
    429 						*warnp = IN_ALL;
    430 						pt = _yconv(year, base, 0, 1,
    431 							pt, ptlim);
    432 					} else	pt = _yconv(year, base, 1, 1,
    433 							pt, ptlim);
    434 				}
    435 				continue;
    436 			case 'v':
    437 				/*
    438 				** From Arnold Robbins' strftime version 3.0:
    439 				** "date as dd-bbb-YYYY"
    440 				** (ado, 1993-05-24)
    441 				*/
    442 				pt = _fmt(sp, "%e-%b-%Y", t, pt, ptlim, warnp,
    443 				    loc);
    444 				continue;
    445 			case 'W':
    446 				pt = _conv((t->tm_yday + DAYSPERWEEK -
    447 					(t->tm_wday ?
    448 					(t->tm_wday - 1) :
    449 					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
    450 					"%02d", pt, ptlim);
    451 				continue;
    452 			case 'w':
    453 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
    454 				continue;
    455 			case 'X':
    456 				pt = _fmt(sp, _TIME_LOCALE(loc)->t_fmt, t, pt,
    457 				    ptlim, warnp, loc);
    458 				continue;
    459 			case 'x':
    460 				{
    461 				int	warn2 = IN_SOME;
    462 
    463 				pt = _fmt(sp, _TIME_LOCALE(loc)->d_fmt, t, pt,
    464 				    ptlim, &warn2, loc);
    465 				if (warn2 == IN_ALL)
    466 					warn2 = IN_THIS;
    467 				if (warn2 > *warnp)
    468 					*warnp = warn2;
    469 				}
    470 				continue;
    471 			case 'y':
    472 				*warnp = IN_ALL;
    473 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
    474 					pt, ptlim);
    475 				continue;
    476 			case 'Y':
    477 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
    478 					pt, ptlim);
    479 				continue;
    480 			case 'Z':
    481 #ifdef TM_ZONE
    482 				if (t->TM_ZONE != NULL)
    483 					pt = _add(t->TM_ZONE, pt, ptlim);
    484 				else
    485 #endif /* defined TM_ZONE */
    486 				if (t->tm_isdst >= 0)
    487 					pt = _add((sp ?
    488 					    tzgetname(sp, t->tm_isdst) :
    489 					    tzname[t->tm_isdst != 0]),
    490 					    pt, ptlim);
    491 				/*
    492 				** C99 says that %Z must be replaced by the
    493 				** empty string if the time zone is not
    494 				** determinable.
    495 				*/
    496 				continue;
    497 			case 'z':
    498 				{
    499 				int		diff;
    500 				char const *	sign;
    501 
    502 				if (t->tm_isdst < 0)
    503 					continue;
    504 #ifdef TM_GMTOFF
    505 				diff = (int)t->TM_GMTOFF;
    506 #else /* !defined TM_GMTOFF */
    507 				/*
    508 				** C99 says that the UTC offset must
    509 				** be computed by looking only at
    510 				** tm_isdst. This requirement is
    511 				** incorrect, since it means the code
    512 				** must rely on magic (in this case
    513 				** altzone and timezone), and the
    514 				** magic might not have the correct
    515 				** offset. Doing things correctly is
    516 				** tricky and requires disobeying C99;
    517 				** see GNU C strftime for details.
    518 				** For now, punt and conform to the
    519 				** standard, even though it's incorrect.
    520 				**
    521 				** C99 says that %z must be replaced by the
    522 				** empty string if the time zone is not
    523 				** determinable, so output nothing if the
    524 				** appropriate variables are not available.
    525 				*/
    526 #ifndef STD_INSPIRED
    527 				if (t->tm_isdst == 0)
    528 #ifdef USG_COMPAT
    529 					diff = -timezone;
    530 #else /* !defined USG_COMPAT */
    531 					continue;
    532 #endif /* !defined USG_COMPAT */
    533 				else
    534 #ifdef ALTZONE
    535 					diff = -altzone;
    536 #else /* !defined ALTZONE */
    537 					continue;
    538 #endif /* !defined ALTZONE */
    539 #else /* defined STD_INSPIRED */
    540 				{
    541 					struct tm tmp;
    542 					time_t lct, gct;
    543 
    544 					/*
    545 					** Get calendar time from t
    546 					** being treated as local.
    547 					*/
    548 					tmp = *t; /* mktime discards const */
    549 					lct = mktime(&tmp);
    550 
    551 					if (lct == (time_t)-1)
    552 						continue;
    553 
    554 					/*
    555 					** Get calendar time from t
    556 					** being treated as GMT.
    557 					**/
    558 					tmp = *t; /* mktime discards const */
    559 					gct = timegm(&tmp);
    560 
    561 					if (gct == (time_t)-1)
    562 						continue;
    563 
    564 					/* LINTED difference will fit int */
    565 					diff = (intmax_t)gct - (intmax_t)lct;
    566 				}
    567 #endif /* defined STD_INSPIRED */
    568 #endif /* !defined TM_GMTOFF */
    569 				if (diff < 0) {
    570 					sign = "-";
    571 					diff = -diff;
    572 				} else	sign = "+";
    573 				pt = _add(sign, pt, ptlim);
    574 				diff /= SECSPERMIN;
    575 				diff = (diff / MINSPERHOUR) * 100 +
    576 					(diff % MINSPERHOUR);
    577 				pt = _conv(diff, "%04d", pt, ptlim);
    578 				}
    579 				continue;
    580 #if 0
    581 			case '+':
    582 				pt = _fmt(sp, _TIME_LOCALE(loc)->date_fmt, t,
    583 				    pt, ptlim, warnp, loc);
    584 				continue;
    585 #endif
    586 			case '%':
    587 			/*
    588 			** X311J/88-090 (4.12.3.5): if conversion char is
    589 			** undefined, behavior is undefined. Print out the
    590 			** character itself as printf(3) also does.
    591 			*/
    592 			default:
    593 				break;
    594 			}
    595 		}
    596 		if (pt == ptlim)
    597 			break;
    598 		*pt++ = *format;
    599 	}
    600 	return pt;
    601 }
    602 
    603 size_t
    604 strftime(char * const s, const size_t maxsize,
    605     const char * const format, const struct tm * const	t)
    606 {
    607 	tzset();
    608 	return strftime_z(NULL, s, maxsize, format, t);
    609 }
    610 
    611 size_t
    612 strftime_l(char * __restrict s, size_t maxsize, const char * __restrict format,
    613     const struct tm * __restrict t, locale_t loc)
    614 {
    615 	tzset();
    616 	return strftime_lz(NULL, s, maxsize, format, t, loc);
    617 }
    618 
    619 static char *
    620 _conv(const int	n, const char *const format, char *const pt,
    621     const char *const ptlim)
    622 {
    623 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
    624 
    625 	(void) snprintf(buf, sizeof(buf), format, n);
    626 	return _add(buf, pt, ptlim);
    627 }
    628 
    629 static char *
    630 _add(const char *str, char *pt, const char *const ptlim)
    631 {
    632 	while (pt < ptlim && (*pt = *str++) != '\0')
    633 		++pt;
    634 	return pt;
    635 }
    636 
    637 /*
    638 ** POSIX and the C Standard are unclear or inconsistent about
    639 ** what %C and %y do if the year is negative or exceeds 9999.
    640 ** Use the convention that %C concatenated with %y yields the
    641 ** same output as %Y, and that %Y contains at least 4 bytes,
    642 ** with more only if necessary.
    643 */
    644 
    645 static char *
    646 _yconv(const int a, const int b, const int convert_top, const int convert_yy,
    647     char *pt, const char *const ptlim)
    648 {
    649 	register int	lead;
    650 	register int	trail;
    651 
    652 #define DIVISOR	100
    653 	trail = a % DIVISOR + b % DIVISOR;
    654 	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
    655 	trail %= DIVISOR;
    656 	if (trail < 0 && lead > 0) {
    657 		trail += DIVISOR;
    658 		--lead;
    659 	} else if (lead < 0 && trail > 0) {
    660 		trail -= DIVISOR;
    661 		++lead;
    662 	}
    663 	if (convert_top) {
    664 		if (lead == 0 && trail < 0)
    665 			pt = _add("-0", pt, ptlim);
    666 		else	pt = _conv(lead, "%02d", pt, ptlim);
    667 	}
    668 	if (convert_yy)
    669 		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
    670 	return pt;
    671 }
    672 
    673 #ifdef LOCALE_HOME
    674 static struct lc_time_T *
    675 _loc(void)
    676 {
    677 	static const char	locale_home[] = LOCALE_HOME;
    678 	static const char	lc_time[] = "LC_TIME";
    679 	static char *		locale_buf;
    680 
    681 	int			fd;
    682 	int			oldsun;	/* "...ain't got nothin' to do..." */
    683 	char *			lbuf;
    684 	char *			name;
    685 	char *			p;
    686 	const char **		ap;
    687 	const char *		plim;
    688 	char			filename[FILENAME_MAX];
    689 	struct stat		st;
    690 	size_t			namesize;
    691 	size_t			bufsize;
    692 
    693 	/*
    694 	** Use localebuf.mon[0] to signal whether locale is already set up.
    695 	*/
    696 	if (localebuf.mon[0])
    697 		return &localebuf;
    698 	name = setlocale(LC_TIME, NULL);
    699 	if (name == NULL || *name == '\0')
    700 		goto no_locale;
    701 	/*
    702 	** If the locale name is the same as our cache, use the cache.
    703 	*/
    704 	lbuf = locale_buf;
    705 	if (lbuf != NULL && strcmp(name, lbuf) == 0) {
    706 		p = lbuf;
    707 		for (ap = (const char **) &localebuf;
    708 			ap < (const char **) (&localebuf + 1);
    709 				++ap)
    710 					*ap = p += strlen(p) + 1;
    711 		return &localebuf;
    712 	}
    713 	/*
    714 	** Slurp the locale file into the cache.
    715 	*/
    716 	namesize = strlen(name) + 1;
    717 	if (sizeof filename <
    718 		((sizeof locale_home) + namesize + (sizeof lc_time)))
    719 			goto no_locale;
    720 	oldsun = 0;
    721 	(void) sprintf(filename, "%s/%s/%s", locale_home, name, lc_time);
    722 	fd = open(filename, O_RDONLY);
    723 	if (fd < 0) {
    724 		/*
    725 		** Old Sun systems have a different naming and data convention.
    726 		*/
    727 		oldsun = 1;
    728 		(void) sprintf(filename, "%s/%s/%s", locale_home,
    729 			lc_time, name);
    730 		fd = open(filename, O_RDONLY);
    731 		if (fd < 0)
    732 			goto no_locale;
    733 	}
    734 	if (fstat(fd, &st) != 0)
    735 		goto bad_locale;
    736 	if (st.st_size <= 0)
    737 		goto bad_locale;
    738 	bufsize = namesize + st.st_size;
    739 	locale_buf = NULL;
    740 	lbuf = (lbuf == NULL) ? malloc(bufsize) : realloc(lbuf, bufsize);
    741 	if (lbuf == NULL)
    742 		goto bad_locale;
    743 	(void) strcpy(lbuf, name);
    744 	p = lbuf + namesize;
    745 	plim = p + st.st_size;
    746 	if (read(fd, p, (size_t) st.st_size) != st.st_size)
    747 		goto bad_lbuf;
    748 	if (close(fd) != 0)
    749 		goto bad_lbuf;
    750 	/*
    751 	** Parse the locale file into localebuf.
    752 	*/
    753 	if (plim[-1] != '\n')
    754 		goto bad_lbuf;
    755 	for (ap = (const char **) &localebuf;
    756 		ap < (const char **) (&localebuf + 1);
    757 			++ap) {
    758 				if (p == plim)
    759 					goto bad_lbuf;
    760 				*ap = p;
    761 				while (*p != '\n')
    762 					++p;
    763 				*p++ = '\0';
    764 	}
    765 	if (oldsun) {
    766 		/*
    767 		** SunOS 4 used an obsolescent format; see localdtconv(3).
    768 		** c_fmt had the ``short format for dates and times together''
    769 		** (SunOS 4 date, "%a %b %e %T %Z %Y" in the C locale);
    770 		** date_fmt had the ``long format for dates''
    771 		** (SunOS 4 strftime %C, "%A, %B %e, %Y" in the C locale).
    772 		** Discard the latter in favor of the former.
    773 		*/
    774 		localebuf.date_fmt = localebuf.c_fmt;
    775 	}
    776 	/*
    777 	** Record the successful parse in the cache.
    778 	*/
    779 	locale_buf = lbuf;
    780 
    781 	return &localebuf;
    782 
    783 bad_lbuf:
    784 	free(lbuf);
    785 bad_locale:
    786 	(void) close(fd);
    787 no_locale:
    788 	localebuf = C_time_locale;
    789 	locale_buf = NULL;
    790 	return &localebuf;
    791 }
    792 #endif /* defined LOCALE_HOME */
    793