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strftime.c revision 1.23
      1 /*	$NetBSD: strftime.c,v 1.23 2012/10/24 00:10:03 christos 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 1.23 2012/10/24 00:10:03 christos Exp $");
     10 #endif
     11 #endif /* LIBC_SCCS and not lint */
     12 
     13 #include "namespace.h"
     14 
     15 /*
     16 ** Based on the UCB version with the ID appearing below.
     17 ** This is ANSIish only when "multibyte character == plain character".
     18 */
     19 
     20 #include "private.h"
     21 
     22 /*
     23 ** We don't use these extensions in strftime operation even when
     24 ** supported by the local tzcode configuration.  A strictly
     25 ** conforming C application may leave them in undefined state.
     26 */
     27 
     28 #ifdef _LIBC
     29 #undef TM_ZONE
     30 #undef TM_GMTOFF
     31 #endif
     32 
     33 /*
     34 ** Copyright (c) 1989, 1993
     35 **	The Regents of the University of California.  All rights reserved.
     36 **
     37 ** Redistribution and use in source and binary forms, with or without
     38 ** modification, are permitted provided that the following conditions
     39 ** are met:
     40 ** 1. Redistributions of source code must retain the above copyright
     41 **    notice, this list of conditions and the following disclaimer.
     42 ** 2. Redistributions in binary form must reproduce the above copyright
     43 **    notice, this list of conditions and the following disclaimer in the
     44 **    documentation and/or other materials provided with the distribution.
     45 ** 3. All advertising materials mentioning features or use of this software
     46 **    must display the following acknowledgement:
     47 **	This product includes software developed by the University of
     48 **	California, Berkeley and its contributors.
     49 ** 4. Neither the name of the University nor the names of its contributors
     50 **    may be used to endorse or promote products derived from this software
     51 **    without specific prior written permission.
     52 **
     53 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     54 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     55 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     56 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     57 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     58 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     59 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     60 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     61 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     62 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     63 ** SUCH DAMAGE.
     64 */
     65 
     66 #ifndef LIBC_SCCS
     67 #ifndef lint
     68 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
     69 #endif /* !defined lint */
     70 #endif /* !defined LIBC_SCCS */
     71 
     72 #include "tzfile.h"
     73 #include "fcntl.h"
     74 #include "locale.h"
     75 
     76 #ifdef __weak_alias
     77 __weak_alias(strftime_z, _strftime_z)
     78 #endif
     79 
     80 #include "sys/localedef.h"
     81 #define Locale	_CurrentTimeLocale
     82 #define c_fmt   d_t_fmt
     83 
     84 static char *	_add(const char *, char *, const char *);
     85 static char *	_conv(int, const char *, char *, const char *);
     86 static char *	_fmt(const timezone_t, const char *, const struct tm *, char *,
     87 			const char *, int *);
     88 static char *	_yconv(int, int, int, int, char *, const char *);
     89 
     90 extern char *	tzname[];
     91 
     92 #ifndef YEAR_2000_NAME
     93 #define YEAR_2000_NAME	"CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
     94 #endif /* !defined YEAR_2000_NAME */
     95 
     96 #define IN_NONE	0
     97 #define IN_SOME	1
     98 #define IN_THIS	2
     99 #define IN_ALL	3
    100 
    101 size_t
    102 strftime_z(const timezone_t sp, char *const s, const size_t maxsize,
    103     const char *const format, const struct tm *const t)
    104 {
    105 	char *	p;
    106 	int	warn;
    107 
    108 	warn = IN_NONE;
    109 	p = _fmt(sp, ((format == NULL) ? "%c" : format), t, s, s + maxsize,
    110 	    &warn);
    111 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
    112 	if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
    113 		(void) fprintf(stderr, "\n");
    114 		if (format == NULL)
    115 			(void) fprintf(stderr, "NULL strftime format ");
    116 		else	(void) fprintf(stderr, "strftime format \"%s\" ",
    117 				format);
    118 		(void) fprintf(stderr, "yields only two digits of years in ");
    119 		if (warn == IN_SOME)
    120 			(void) fprintf(stderr, "some locales");
    121 		else if (warn == IN_THIS)
    122 			(void) fprintf(stderr, "the current locale");
    123 		else	(void) fprintf(stderr, "all locales");
    124 		(void) fprintf(stderr, "\n");
    125 	}
    126 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
    127 	if (p == s + maxsize)
    128 		return 0;
    129 	*p = '\0';
    130 	return p - s;
    131 }
    132 
    133 static char *
    134 _fmt(const timezone_t sp, const char *format, const struct tm *const t,
    135 	char *pt, const char *const ptlim, int *warnp)
    136 {
    137 	for ( ; *format; ++format) {
    138 		if (*format == '%') {
    139 label:
    140 			switch (*++format) {
    141 			case '\0':
    142 				--format;
    143 				break;
    144 			case 'A':
    145 				pt = _add((t->tm_wday < 0 ||
    146 					t->tm_wday >= DAYSPERWEEK) ?
    147 					"?" : Locale->day[t->tm_wday],
    148 					pt, ptlim);
    149 				continue;
    150 			case 'a':
    151 				pt = _add((t->tm_wday < 0 ||
    152 					t->tm_wday >= DAYSPERWEEK) ?
    153 					"?" : Locale->abday[t->tm_wday],
    154 					pt, ptlim);
    155 				continue;
    156 			case 'B':
    157 				pt = _add((t->tm_mon < 0 ||
    158 					t->tm_mon >= MONSPERYEAR) ?
    159 					"?" : Locale->mon[t->tm_mon],
    160 					pt, ptlim);
    161 				continue;
    162 			case 'b':
    163 			case 'h':
    164 				pt = _add((t->tm_mon < 0 ||
    165 					t->tm_mon >= MONSPERYEAR) ?
    166 					"?" : Locale->abmon[t->tm_mon],
    167 					pt, ptlim);
    168 				continue;
    169 			case 'C':
    170 				/*
    171 				** %C used to do a...
    172 				**	_fmt("%a %b %e %X %Y", t);
    173 				** ...whereas now POSIX 1003.2 calls for
    174 				** something completely different.
    175 				** (ado, 1993-05-24)
    176 				*/
    177 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
    178 					pt, ptlim);
    179 				continue;
    180 			case 'c':
    181 				{
    182 				int warn2 = IN_SOME;
    183 
    184 				pt = _fmt(sp, Locale->c_fmt, t, pt, ptlim, &warn2);
    185 				if (warn2 == IN_ALL)
    186 					warn2 = IN_THIS;
    187 				if (warn2 > *warnp)
    188 					*warnp = warn2;
    189 				}
    190 				continue;
    191 			case 'D':
    192 				pt = _fmt(sp, "%m/%d/%y", t, pt, ptlim, warnp);
    193 				continue;
    194 			case 'd':
    195 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
    196 				continue;
    197 			case 'E':
    198 			case 'O':
    199 				/*
    200 				** C99 locale modifiers.
    201 				** The sequences
    202 				**	%Ec %EC %Ex %EX %Ey %EY
    203 				**	%Od %oe %OH %OI %Om %OM
    204 				**	%OS %Ou %OU %OV %Ow %OW %Oy
    205 				** are supposed to provide alternate
    206 				** representations.
    207 				*/
    208 				goto label;
    209 			case 'e':
    210 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
    211 				continue;
    212 			case 'F':
    213 				pt = _fmt(sp, "%Y-%m-%d", t, pt, ptlim, warnp);
    214 				continue;
    215 			case 'H':
    216 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
    217 				continue;
    218 			case 'I':
    219 				pt = _conv((t->tm_hour % 12) ?
    220 					(t->tm_hour % 12) : 12,
    221 					"%02d", pt, ptlim);
    222 				continue;
    223 			case 'j':
    224 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
    225 				continue;
    226 			case 'k':
    227 				/*
    228 				** This used to be...
    229 				**	_conv(t->tm_hour % 12 ?
    230 				**		t->tm_hour % 12 : 12, 2, ' ');
    231 				** ...and has been changed to the below to
    232 				** match SunOS 4.1.1 and Arnold Robbins'
    233 				** strftime version 3.0. That is, "%k" and
    234 				** "%l" have been swapped.
    235 				** (ado, 1993-05-24)
    236 				*/
    237 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
    238 				continue;
    239 #ifdef KITCHEN_SINK
    240 			case 'K':
    241 				/*
    242 				** After all this time, still unclaimed!
    243 				*/
    244 				pt = _add("kitchen sink", pt, ptlim);
    245 				continue;
    246 #endif /* defined KITCHEN_SINK */
    247 			case 'l':
    248 				/*
    249 				** This used to be...
    250 				**	_conv(t->tm_hour, 2, ' ');
    251 				** ...and has been changed to the below to
    252 				** match SunOS 4.1.1 and Arnold Robbin's
    253 				** strftime version 3.0. That is, "%k" and
    254 				** "%l" have been swapped.
    255 				** (ado, 1993-05-24)
    256 				*/
    257 				pt = _conv((t->tm_hour % 12) ?
    258 					(t->tm_hour % 12) : 12,
    259 					"%2d", pt, ptlim);
    260 				continue;
    261 			case 'M':
    262 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
    263 				continue;
    264 			case 'm':
    265 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
    266 				continue;
    267 			case 'n':
    268 				pt = _add("\n", pt, ptlim);
    269 				continue;
    270 			case 'p':
    271 				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
    272 					Locale->am_pm[1] :
    273 					Locale->am_pm[0],
    274 					pt, ptlim);
    275 				continue;
    276 			case 'R':
    277 				pt = _fmt(sp, "%H:%M", t, pt, ptlim, warnp);
    278 				continue;
    279 			case 'r':
    280 				pt = _fmt(sp, Locale->t_fmt_ampm, t, pt, ptlim,
    281 				       	warnp);
    282 				continue;
    283 			case 'S':
    284 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
    285 				continue;
    286 			case 's':
    287 				{
    288 					struct tm	tm;
    289 					char		buf[INT_STRLEN_MAXIMUM(
    290 								time_t) + 1];
    291 					time_t		mkt;
    292 
    293 					tm = *t;
    294 					mkt = mktime(&tm);
    295 					/* CONSTCOND */
    296 					if (TYPE_SIGNED(time_t))
    297 						(void) snprintf(buf, sizeof(buf),
    298 						    "%lld", (long long) mkt);
    299 					else	(void) snprintf(buf, sizeof(buf),
    300 						    "%llu", (unsigned long long)
    301 						    mkt);
    302 					pt = _add(buf, pt, ptlim);
    303 				}
    304 				continue;
    305 			case 'T':
    306 				pt = _fmt(sp, "%H:%M:%S", t, pt, ptlim, warnp);
    307 				continue;
    308 			case 't':
    309 				pt = _add("\t", pt, ptlim);
    310 				continue;
    311 			case 'U':
    312 				pt = _conv((t->tm_yday + DAYSPERWEEK -
    313 					t->tm_wday) / DAYSPERWEEK,
    314 					"%02d", pt, ptlim);
    315 				continue;
    316 			case 'u':
    317 				/*
    318 				** From Arnold Robbins' strftime version 3.0:
    319 				** "ISO 8601: Weekday as a decimal number
    320 				** [1 (Monday) - 7]"
    321 				** (ado, 1993-05-24)
    322 				*/
    323 				pt = _conv((t->tm_wday == 0) ?
    324 					DAYSPERWEEK : t->tm_wday,
    325 					"%d", pt, ptlim);
    326 				continue;
    327 			case 'V':	/* ISO 8601 week number */
    328 			case 'G':	/* ISO 8601 year (four digits) */
    329 			case 'g':	/* ISO 8601 year (two digits) */
    330 /*
    331 ** From Arnold Robbins' strftime version 3.0: "the week number of the
    332 ** year (the first Monday as the first day of week 1) as a decimal number
    333 ** (01-53)."
    334 ** (ado, 1993-05-24)
    335 **
    336 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
    337 ** "Week 01 of a year is per definition the first week which has the
    338 ** Thursday in this year, which is equivalent to the week which contains
    339 ** the fourth day of January. In other words, the first week of a new year
    340 ** is the week which has the majority of its days in the new year. Week 01
    341 ** might also contain days from the previous year and the week before week
    342 ** 01 of a year is the last week (52 or 53) of the previous year even if
    343 ** it contains days from the new year. A week starts with Monday (day 1)
    344 ** and ends with Sunday (day 7). For example, the first week of the year
    345 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
    346 ** (ado, 1996-01-02)
    347 */
    348 				{
    349 					int	year;
    350 					int	base;
    351 					int	yday;
    352 					int	wday;
    353 					int	w;
    354 
    355 					year = t->tm_year;
    356 					base = TM_YEAR_BASE;
    357 					yday = t->tm_yday;
    358 					wday = t->tm_wday;
    359 					for ( ; ; ) {
    360 						int	len;
    361 						int	bot;
    362 						int	top;
    363 
    364 						len = isleap_sum(year, base) ?
    365 							DAYSPERLYEAR :
    366 							DAYSPERNYEAR;
    367 						/*
    368 						** What yday (-3 ... 3) does
    369 						** the ISO year begin on?
    370 						*/
    371 						bot = ((yday + 11 - wday) %
    372 							DAYSPERWEEK) - 3;
    373 						/*
    374 						** What yday does the NEXT
    375 						** ISO year begin on?
    376 						*/
    377 						top = bot -
    378 							(len % DAYSPERWEEK);
    379 						if (top < -3)
    380 							top += DAYSPERWEEK;
    381 						top += len;
    382 						if (yday >= top) {
    383 							++base;
    384 							w = 1;
    385 							break;
    386 						}
    387 						if (yday >= bot) {
    388 							w = 1 + ((yday - bot) /
    389 								DAYSPERWEEK);
    390 							break;
    391 						}
    392 						--base;
    393 						yday += isleap_sum(year, base) ?
    394 							DAYSPERLYEAR :
    395 							DAYSPERNYEAR;
    396 					}
    397 #ifdef XPG4_1994_04_09
    398 					if ((w == 52 &&
    399 						t->tm_mon == TM_JANUARY) ||
    400 						(w == 1 &&
    401 						t->tm_mon == TM_DECEMBER))
    402 							w = 53;
    403 #endif /* defined XPG4_1994_04_09 */
    404 					if (*format == 'V')
    405 						pt = _conv(w, "%02d",
    406 							pt, ptlim);
    407 					else if (*format == 'g') {
    408 						*warnp = IN_ALL;
    409 						pt = _yconv(year, base, 0, 1,
    410 							pt, ptlim);
    411 					} else	pt = _yconv(year, base, 1, 1,
    412 							pt, ptlim);
    413 				}
    414 				continue;
    415 			case 'v':
    416 				/*
    417 				** From Arnold Robbins' strftime version 3.0:
    418 				** "date as dd-bbb-YYYY"
    419 				** (ado, 1993-05-24)
    420 				*/
    421 				pt = _fmt(sp, "%e-%b-%Y", t, pt, ptlim, warnp);
    422 				continue;
    423 			case 'W':
    424 				pt = _conv((t->tm_yday + DAYSPERWEEK -
    425 					(t->tm_wday ?
    426 					(t->tm_wday - 1) :
    427 					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
    428 					"%02d", pt, ptlim);
    429 				continue;
    430 			case 'w':
    431 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
    432 				continue;
    433 			case 'X':
    434 				pt = _fmt(sp, Locale->t_fmt, t, pt, ptlim, warnp);
    435 				continue;
    436 			case 'x':
    437 				{
    438 				int	warn2 = IN_SOME;
    439 
    440 				pt = _fmt(sp, Locale->d_fmt, t, pt, ptlim, &warn2);
    441 				if (warn2 == IN_ALL)
    442 					warn2 = IN_THIS;
    443 				if (warn2 > *warnp)
    444 					*warnp = warn2;
    445 				}
    446 				continue;
    447 			case 'y':
    448 				*warnp = IN_ALL;
    449 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
    450 					pt, ptlim);
    451 				continue;
    452 			case 'Y':
    453 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
    454 					pt, ptlim);
    455 				continue;
    456 			case 'Z':
    457 #ifdef TM_ZONE
    458 				if (t->TM_ZONE != NULL)
    459 					pt = _add(t->TM_ZONE, pt, ptlim);
    460 				else
    461 #endif /* defined TM_ZONE */
    462 				if (t->tm_isdst >= 0)
    463 					pt = _add((sp ?
    464 					    tzgetname(sp, t->tm_isdst) :
    465 					    tzname[t->tm_isdst != 0]),
    466 					    pt, ptlim);
    467 				/*
    468 				** C99 says that %Z must be replaced by the
    469 				** empty string if the time zone is not
    470 				** determinable.
    471 				*/
    472 				continue;
    473 			case 'z':
    474 				{
    475 				int		diff;
    476 				char const *	sign;
    477 
    478 				if (t->tm_isdst < 0)
    479 					continue;
    480 #ifdef TM_GMTOFF
    481 				diff = (int)t->TM_GMTOFF;
    482 #else /* !defined TM_GMTOFF */
    483 				/*
    484 				** C99 says that the UTC offset must
    485 				** be computed by looking only at
    486 				** tm_isdst. This requirement is
    487 				** incorrect, since it means the code
    488 				** must rely on magic (in this case
    489 				** altzone and timezone), and the
    490 				** magic might not have the correct
    491 				** offset. Doing things correctly is
    492 				** tricky and requires disobeying C99;
    493 				** see GNU C strftime for details.
    494 				** For now, punt and conform to the
    495 				** standard, even though it's incorrect.
    496 				**
    497 				** C99 says that %z must be replaced by the
    498 				** empty string if the time zone is not
    499 				** determinable, so output nothing if the
    500 				** appropriate variables are not available.
    501 				*/
    502 #ifndef STD_INSPIRED
    503 				if (t->tm_isdst == 0)
    504 #ifdef USG_COMPAT
    505 					diff = -timezone;
    506 #else /* !defined USG_COMPAT */
    507 					continue;
    508 #endif /* !defined USG_COMPAT */
    509 				else
    510 #ifdef ALTZONE
    511 					diff = -altzone;
    512 #else /* !defined ALTZONE */
    513 					continue;
    514 #endif /* !defined ALTZONE */
    515 #else /* defined STD_INSPIRED */
    516 				{
    517 					struct tm tmp;
    518 					time_t lct, gct;
    519 
    520 					/*
    521 					** Get calendar time from t
    522 					** being treated as local.
    523 					*/
    524 					tmp = *t; /* mktime discards const */
    525 					lct = mktime(&tmp);
    526 
    527 					if (lct == (time_t)-1)
    528 						continue;
    529 
    530 					/*
    531 					** Get calendar time from t
    532 					** being treated as GMT.
    533 					**/
    534 					tmp = *t; /* mktime discards const */
    535 					gct = timegm(&tmp);
    536 
    537 					if (gct == (time_t)-1)
    538 						continue;
    539 
    540 					/* LINTED difference will fit int */
    541 					diff = (intmax_t)gct - (intmax_t)lct;
    542 				}
    543 #endif /* defined STD_INSPIRED */
    544 #endif /* !defined TM_GMTOFF */
    545 				if (diff < 0) {
    546 					sign = "-";
    547 					diff = -diff;
    548 				} else	sign = "+";
    549 				pt = _add(sign, pt, ptlim);
    550 				diff /= SECSPERMIN;
    551 				diff = (diff / MINSPERHOUR) * 100 +
    552 					(diff % MINSPERHOUR);
    553 				pt = _conv(diff, "%04d", pt, ptlim);
    554 				}
    555 				continue;
    556 #if 0
    557 			case '+':
    558 				pt = _fmt(sp, Locale->date_fmt, t, pt, ptlim,
    559 					warnp);
    560 				continue;
    561 #endif
    562 			case '%':
    563 			/*
    564 			** X311J/88-090 (4.12.3.5): if conversion char is
    565 			** undefined, behavior is undefined. Print out the
    566 			** character itself as printf(3) also does.
    567 			*/
    568 			default:
    569 				break;
    570 			}
    571 		}
    572 		if (pt == ptlim)
    573 			break;
    574 		*pt++ = *format;
    575 	}
    576 	return pt;
    577 }
    578 
    579 size_t
    580 strftime(char * const s, const size_t maxsize,
    581     const char * const format, const struct tm * const	t)
    582 {
    583 	tzset();
    584 	return strftime_z(NULL, s, maxsize, format, t);
    585 }
    586 
    587 static char *
    588 _conv(const int	n, const char *const format, char *const pt,
    589     const char *const ptlim)
    590 {
    591 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
    592 
    593 	(void) snprintf(buf, sizeof(buf), format, n);
    594 	return _add(buf, pt, ptlim);
    595 }
    596 
    597 static char *
    598 _add(const char *str, char *pt, const char *const ptlim)
    599 {
    600 	while (pt < ptlim && (*pt = *str++) != '\0')
    601 		++pt;
    602 	return pt;
    603 }
    604 
    605 /*
    606 ** POSIX and the C Standard are unclear or inconsistent about
    607 ** what %C and %y do if the year is negative or exceeds 9999.
    608 ** Use the convention that %C concatenated with %y yields the
    609 ** same output as %Y, and that %Y contains at least 4 bytes,
    610 ** with more only if necessary.
    611 */
    612 
    613 static char *
    614 _yconv(const int a, const int b, const int convert_top, const int convert_yy,
    615     char *pt, const char *const ptlim)
    616 {
    617 	register int	lead;
    618 	register int	trail;
    619 
    620 #define DIVISOR	100
    621 	trail = a % DIVISOR + b % DIVISOR;
    622 	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
    623 	trail %= DIVISOR;
    624 	if (trail < 0 && lead > 0) {
    625 		trail += DIVISOR;
    626 		--lead;
    627 	} else if (lead < 0 && trail > 0) {
    628 		trail -= DIVISOR;
    629 		++lead;
    630 	}
    631 	if (convert_top) {
    632 		if (lead == 0 && trail < 0)
    633 			pt = _add("-0", pt, ptlim);
    634 		else	pt = _conv(lead, "%02d", pt, ptlim);
    635 	}
    636 	if (convert_yy)
    637 		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
    638 	return pt;
    639 }
    640 
    641 #ifdef LOCALE_HOME
    642 static struct lc_time_T *
    643 _loc(void)
    644 {
    645 	static const char	locale_home[] = LOCALE_HOME;
    646 	static const char	lc_time[] = "LC_TIME";
    647 	static char *		locale_buf;
    648 
    649 	int			fd;
    650 	int			oldsun;	/* "...ain't got nothin' to do..." */
    651 	char *			lbuf;
    652 	char *			name;
    653 	char *			p;
    654 	const char **		ap;
    655 	const char *		plim;
    656 	char			filename[FILENAME_MAX];
    657 	struct stat		st;
    658 	size_t			namesize;
    659 	size_t			bufsize;
    660 
    661 	/*
    662 	** Use localebuf.mon[0] to signal whether locale is already set up.
    663 	*/
    664 	if (localebuf.mon[0])
    665 		return &localebuf;
    666 	name = setlocale(LC_TIME, NULL);
    667 	if (name == NULL || *name == '\0')
    668 		goto no_locale;
    669 	/*
    670 	** If the locale name is the same as our cache, use the cache.
    671 	*/
    672 	lbuf = locale_buf;
    673 	if (lbuf != NULL && strcmp(name, lbuf) == 0) {
    674 		p = lbuf;
    675 		for (ap = (const char **) &localebuf;
    676 			ap < (const char **) (&localebuf + 1);
    677 				++ap)
    678 					*ap = p += strlen(p) + 1;
    679 		return &localebuf;
    680 	}
    681 	/*
    682 	** Slurp the locale file into the cache.
    683 	*/
    684 	namesize = strlen(name) + 1;
    685 	if (sizeof filename <
    686 		((sizeof locale_home) + namesize + (sizeof lc_time)))
    687 			goto no_locale;
    688 	oldsun = 0;
    689 	(void) sprintf(filename, "%s/%s/%s", locale_home, name, lc_time);
    690 	fd = open(filename, O_RDONLY);
    691 	if (fd < 0) {
    692 		/*
    693 		** Old Sun systems have a different naming and data convention.
    694 		*/
    695 		oldsun = 1;
    696 		(void) sprintf(filename, "%s/%s/%s", locale_home,
    697 			lc_time, name);
    698 		fd = open(filename, O_RDONLY);
    699 		if (fd < 0)
    700 			goto no_locale;
    701 	}
    702 	if (fstat(fd, &st) != 0)
    703 		goto bad_locale;
    704 	if (st.st_size <= 0)
    705 		goto bad_locale;
    706 	bufsize = namesize + st.st_size;
    707 	locale_buf = NULL;
    708 	lbuf = (lbuf == NULL) ? malloc(bufsize) : realloc(lbuf, bufsize);
    709 	if (lbuf == NULL)
    710 		goto bad_locale;
    711 	(void) strcpy(lbuf, name);
    712 	p = lbuf + namesize;
    713 	plim = p + st.st_size;
    714 	if (read(fd, p, (size_t) st.st_size) != st.st_size)
    715 		goto bad_lbuf;
    716 	if (close(fd) != 0)
    717 		goto bad_lbuf;
    718 	/*
    719 	** Parse the locale file into localebuf.
    720 	*/
    721 	if (plim[-1] != '\n')
    722 		goto bad_lbuf;
    723 	for (ap = (const char **) &localebuf;
    724 		ap < (const char **) (&localebuf + 1);
    725 			++ap) {
    726 				if (p == plim)
    727 					goto bad_lbuf;
    728 				*ap = p;
    729 				while (*p != '\n')
    730 					++p;
    731 				*p++ = '\0';
    732 	}
    733 	if (oldsun) {
    734 		/*
    735 		** SunOS 4 used an obsolescent format; see localdtconv(3).
    736 		** c_fmt had the ``short format for dates and times together''
    737 		** (SunOS 4 date, "%a %b %e %T %Z %Y" in the C locale);
    738 		** date_fmt had the ``long format for dates''
    739 		** (SunOS 4 strftime %C, "%A, %B %e, %Y" in the C locale).
    740 		** Discard the latter in favor of the former.
    741 		*/
    742 		localebuf.date_fmt = localebuf.c_fmt;
    743 	}
    744 	/*
    745 	** Record the successful parse in the cache.
    746 	*/
    747 	locale_buf = lbuf;
    748 
    749 	return &localebuf;
    750 
    751 bad_lbuf:
    752 	free(lbuf);
    753 bad_locale:
    754 	(void) close(fd);
    755 no_locale:
    756 	localebuf = C_time_locale;
    757 	locale_buf = NULL;
    758 	return &localebuf;
    759 }
    760 #endif /* defined LOCALE_HOME */
    761