xref: /netbsd/lib/libc/time/strftime.c (revision 6550d01e)
1 /*	$NetBSD: strftime.c,v 1.21 2010/12/16 18:38:07 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 1.21 2010/12/16 18:38:07 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(n, format, pt, ptlim)
589 const int		n;
590 const char * const	format;
591 char * const		pt;
592 const char * const	ptlim;
593 {
594 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
595 
596 	(void) snprintf(buf, sizeof(buf), format, n);
597 	return _add(buf, pt, ptlim);
598 }
599 
600 static char *
601 _add(str, pt, ptlim)
602 const char *		str;
603 char *			pt;
604 const char * const	ptlim;
605 {
606 	while (pt < ptlim && (*pt = *str++) != '\0')
607 		++pt;
608 	return pt;
609 }
610 
611 /*
612 ** POSIX and the C Standard are unclear or inconsistent about
613 ** what %C and %y do if the year is negative or exceeds 9999.
614 ** Use the convention that %C concatenated with %y yields the
615 ** same output as %Y, and that %Y contains at least 4 bytes,
616 ** with more only if necessary.
617 */
618 
619 static char *
620 _yconv(a, b, convert_top, convert_yy, pt, ptlim)
621 const int		a;
622 const int		b;
623 const int		convert_top;
624 const int		convert_yy;
625 char *			pt;
626 const char * const	ptlim;
627 {
628 	register int	lead;
629 	register int	trail;
630 
631 #define DIVISOR	100
632 	trail = a % DIVISOR + b % DIVISOR;
633 	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
634 	trail %= DIVISOR;
635 	if (trail < 0 && lead > 0) {
636 		trail += DIVISOR;
637 		--lead;
638 	} else if (lead < 0 && trail > 0) {
639 		trail -= DIVISOR;
640 		++lead;
641 	}
642 	if (convert_top) {
643 		if (lead == 0 && trail < 0)
644 			pt = _add("-0", pt, ptlim);
645 		else	pt = _conv(lead, "%02d", pt, ptlim);
646 	}
647 	if (convert_yy)
648 		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
649 	return pt;
650 }
651 
652 #ifdef LOCALE_HOME
653 static struct lc_time_T *
654 _loc(void)
655 {
656 	static const char	locale_home[] = LOCALE_HOME;
657 	static const char	lc_time[] = "LC_TIME";
658 	static char *		locale_buf;
659 
660 	int			fd;
661 	int			oldsun;	/* "...ain't got nothin' to do..." */
662 	char *			lbuf;
663 	char *			name;
664 	char *			p;
665 	const char **		ap;
666 	const char *		plim;
667 	char			filename[FILENAME_MAX];
668 	struct stat		st;
669 	size_t			namesize;
670 	size_t			bufsize;
671 
672 	/*
673 	** Use localebuf.mon[0] to signal whether locale is already set up.
674 	*/
675 	if (localebuf.mon[0])
676 		return &localebuf;
677 	name = setlocale(LC_TIME, (char *) NULL);
678 	if (name == NULL || *name == '\0')
679 		goto no_locale;
680 	/*
681 	** If the locale name is the same as our cache, use the cache.
682 	*/
683 	lbuf = locale_buf;
684 	if (lbuf != NULL && strcmp(name, lbuf) == 0) {
685 		p = lbuf;
686 		for (ap = (const char **) &localebuf;
687 			ap < (const char **) (&localebuf + 1);
688 				++ap)
689 					*ap = p += strlen(p) + 1;
690 		return &localebuf;
691 	}
692 	/*
693 	** Slurp the locale file into the cache.
694 	*/
695 	namesize = strlen(name) + 1;
696 	if (sizeof filename <
697 		((sizeof locale_home) + namesize + (sizeof lc_time)))
698 			goto no_locale;
699 	oldsun = 0;
700 	(void) sprintf(filename, "%s/%s/%s", locale_home, name, lc_time);
701 	fd = open(filename, O_RDONLY);
702 	if (fd < 0) {
703 		/*
704 		** Old Sun systems have a different naming and data convention.
705 		*/
706 		oldsun = 1;
707 		(void) sprintf(filename, "%s/%s/%s", locale_home,
708 			lc_time, name);
709 		fd = open(filename, O_RDONLY);
710 		if (fd < 0)
711 			goto no_locale;
712 	}
713 	if (fstat(fd, &st) != 0)
714 		goto bad_locale;
715 	if (st.st_size <= 0)
716 		goto bad_locale;
717 	bufsize = namesize + st.st_size;
718 	locale_buf = NULL;
719 	lbuf = (lbuf == NULL) ? malloc(bufsize) : realloc(lbuf, bufsize);
720 	if (lbuf == NULL)
721 		goto bad_locale;
722 	(void) strcpy(lbuf, name);
723 	p = lbuf + namesize;
724 	plim = p + st.st_size;
725 	if (read(fd, p, (size_t) st.st_size) != st.st_size)
726 		goto bad_lbuf;
727 	if (close(fd) != 0)
728 		goto bad_lbuf;
729 	/*
730 	** Parse the locale file into localebuf.
731 	*/
732 	if (plim[-1] != '\n')
733 		goto bad_lbuf;
734 	for (ap = (const char **) &localebuf;
735 		ap < (const char **) (&localebuf + 1);
736 			++ap) {
737 				if (p == plim)
738 					goto bad_lbuf;
739 				*ap = p;
740 				while (*p != '\n')
741 					++p;
742 				*p++ = '\0';
743 	}
744 	if (oldsun) {
745 		/*
746 		** SunOS 4 used an obsolescent format; see localdtconv(3).
747 		** c_fmt had the ``short format for dates and times together''
748 		** (SunOS 4 date, "%a %b %e %T %Z %Y" in the C locale);
749 		** date_fmt had the ``long format for dates''
750 		** (SunOS 4 strftime %C, "%A, %B %e, %Y" in the C locale).
751 		** Discard the latter in favor of the former.
752 		*/
753 		localebuf.date_fmt = localebuf.c_fmt;
754 	}
755 	/*
756 	** Record the successful parse in the cache.
757 	*/
758 	locale_buf = lbuf;
759 
760 	return &localebuf;
761 
762 bad_lbuf:
763 	free(lbuf);
764 bad_locale:
765 	(void) close(fd);
766 no_locale:
767 	localebuf = C_time_locale;
768 	locale_buf = NULL;
769 	return &localebuf;
770 }
771 #endif /* defined LOCALE_HOME */
772