xref: /openbsd-src/lib/libc/time/strftime.c (revision d13be5d47e4149db2549a9828e244d59dbc43f15)
1 /*	$OpenBSD: strftime.c,v 1.20 2009/10/27 23:59:59 deraadt Exp $ */
2 #include "private.h"
3 
4 /*
5 ** Based on the UCB version with the ID appearing below.
6 ** This is ANSIish only when "multibyte character == plain character".
7 **
8 ** Copyright (c) 1989, 1993
9 **	The Regents of the University of California.  All rights reserved.
10 **
11 ** Redistribution and use in source and binary forms, with or without
12 ** modification, are permitted provided that the following conditions
13 ** are met:
14 ** 1. Redistributions of source code must retain the above copyright
15 **    notice, this list of conditions and the following disclaimer.
16 ** 2. Redistributions in binary form must reproduce the above copyright
17 **    notice, this list of conditions and the following disclaimer in the
18 **    documentation and/or other materials provided with the distribution.
19 ** 3. Neither the name of the University nor the names of its contributors
20 **    may be used to endorse or promote products derived from this software
21 **    without specific prior written permission.
22 **
23 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 ** SUCH DAMAGE.
34 */
35 
36 #include "tzfile.h"
37 #include "fcntl.h"
38 #include "locale.h"
39 
40 struct lc_time_T {
41 	const char *	mon[MONSPERYEAR];
42 	const char *	month[MONSPERYEAR];
43 	const char *	wday[DAYSPERWEEK];
44 	const char *	weekday[DAYSPERWEEK];
45 	const char *	X_fmt;
46 	const char *	x_fmt;
47 	const char *	c_fmt;
48 	const char *	am;
49 	const char *	pm;
50 	const char *	date_fmt;
51 };
52 
53 #ifdef LOCALE_HOME
54 #include "sys/stat.h"
55 static struct lc_time_T		localebuf;
56 static struct lc_time_T *	_loc(void);
57 #define Locale	_loc()
58 #endif /* defined LOCALE_HOME */
59 #ifndef LOCALE_HOME
60 #define Locale	(&C_time_locale)
61 #endif /* !defined LOCALE_HOME */
62 
63 static const struct lc_time_T	C_time_locale = {
64 	{
65 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
66 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
67 	}, {
68 		"January", "February", "March", "April", "May", "June",
69 		"July", "August", "September", "October", "November", "December"
70 	}, {
71 		"Sun", "Mon", "Tue", "Wed",
72 		"Thu", "Fri", "Sat"
73 	}, {
74 		"Sunday", "Monday", "Tuesday", "Wednesday",
75 		"Thursday", "Friday", "Saturday"
76 	},
77 
78 	/* X_fmt */
79 	"%H:%M:%S",
80 
81 	/*
82 	** x_fmt
83 	** C99 requires this format.
84 	** Using just numbers (as here) makes Quakers happier;
85 	** it's also compatible with SVR4.
86 	*/
87 	"%m/%d/%y",
88 
89 	/*
90 	** c_fmt
91 	** C99 requires this format.
92 	** Previously this code used "%D %X", but we now conform to C99.
93 	** Note that
94 	**	"%a %b %d %H:%M:%S %Y"
95 	** is used by Solaris 2.3.
96 	*/
97 	"%a %b %e %T %Y",
98 
99 	/* am */
100 	"AM",
101 
102 	/* pm */
103 	"PM",
104 
105 	/* date_fmt */
106 	"%a %b %e %H:%M:%S %Z %Y"
107 };
108 
109 static char *	_add(const char *, char *, const char *);
110 static char *	_conv(int, const char *, char *, const char *);
111 static char *	_fmt(const char *, const struct tm *, char *, const char *,
112 			int *);
113 static char *	_yconv(int, int, int, int, char *, const char *);
114 
115 extern char *	tzname[];
116 
117 #ifndef YEAR_2000_NAME
118 #define YEAR_2000_NAME	"CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
119 #endif /* !defined YEAR_2000_NAME */
120 
121 #define IN_NONE	0
122 #define IN_SOME	1
123 #define IN_THIS	2
124 #define IN_ALL	3
125 
126 size_t
127 strftime(s, maxsize, format, t)
128 char * const		s;
129 const size_t		maxsize;
130 const char * const	format;
131 const struct tm * const	t;
132 {
133 	char *	p;
134 	int	warn;
135 
136 	tzset();
137 #ifdef LOCALE_HOME
138 	localebuf.mon[0] = 0;
139 #endif /* defined LOCALE_HOME */
140 	warn = IN_NONE;
141 	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
142 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
143 	if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
144 		(void) fprintf(stderr, "\n");
145 		if (format == NULL)
146 			(void) fprintf(stderr, "NULL strftime format ");
147 		else	(void) fprintf(stderr, "strftime format \"%s\" ",
148 				format);
149 		(void) fprintf(stderr, "yields only two digits of years in ");
150 		if (warn == IN_SOME)
151 			(void) fprintf(stderr, "some locales");
152 		else if (warn == IN_THIS)
153 			(void) fprintf(stderr, "the current locale");
154 		else	(void) fprintf(stderr, "all locales");
155 		(void) fprintf(stderr, "\n");
156 	}
157 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
158 	if (p == s + maxsize) {
159 		if (maxsize > 0)
160 			s[maxsize - 1] = '\0';
161 		return 0;
162 	}
163 	*p = '\0';
164 	return p - s;
165 }
166 
167 static char *
168 _fmt(format, t, pt, ptlim, warnp)
169 const char *		format;
170 const struct tm * const	t;
171 char *			pt;
172 const char * const	ptlim;
173 int *			warnp;
174 {
175 	for ( ; *format; ++format) {
176 		if (*format == '%') {
177 label:
178 			switch (*++format) {
179 			case '\0':
180 				--format;
181 				break;
182 			case 'A':
183 				pt = _add((t->tm_wday < 0 ||
184 					t->tm_wday >= DAYSPERWEEK) ?
185 					"?" : Locale->weekday[t->tm_wday],
186 					pt, ptlim);
187 				continue;
188 			case 'a':
189 				pt = _add((t->tm_wday < 0 ||
190 					t->tm_wday >= DAYSPERWEEK) ?
191 					"?" : Locale->wday[t->tm_wday],
192 					pt, ptlim);
193 				continue;
194 			case 'B':
195 				pt = _add((t->tm_mon < 0 ||
196 					t->tm_mon >= MONSPERYEAR) ?
197 					"?" : Locale->month[t->tm_mon],
198 					pt, ptlim);
199 				continue;
200 			case 'b':
201 			case 'h':
202 				pt = _add((t->tm_mon < 0 ||
203 					t->tm_mon >= MONSPERYEAR) ?
204 					"?" : Locale->mon[t->tm_mon],
205 					pt, ptlim);
206 				continue;
207 			case 'C':
208 				/*
209 				** %C used to do a...
210 				**	_fmt("%a %b %e %X %Y", t);
211 				** ...whereas now POSIX 1003.2 calls for
212 				** something completely different.
213 				** (ado, 1993-05-24)
214 				*/
215 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
216 					pt, ptlim);
217 				continue;
218 			case 'c':
219 				{
220 				int warn2 = IN_SOME;
221 
222 				pt = _fmt(Locale->c_fmt, t, pt, ptlim, &warn2);
223 				if (warn2 == IN_ALL)
224 					warn2 = IN_THIS;
225 				if (warn2 > *warnp)
226 					*warnp = warn2;
227 				}
228 				continue;
229 			case 'D':
230 				pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
231 				continue;
232 			case 'd':
233 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
234 				continue;
235 			case 'E':
236 			case 'O':
237 				/*
238 				** C99 locale modifiers.
239 				** The sequences
240 				**	%Ec %EC %Ex %EX %Ey %EY
241 				**	%Od %oe %OH %OI %Om %OM
242 				**	%OS %Ou %OU %OV %Ow %OW %Oy
243 				** are supposed to provide alternate
244 				** representations.
245 				*/
246 				goto label;
247 			case 'e':
248 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
249 				continue;
250 			case 'F':
251 				pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
252 				continue;
253 			case 'H':
254 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
255 				continue;
256 			case 'I':
257 				pt = _conv((t->tm_hour % 12) ?
258 					(t->tm_hour % 12) : 12,
259 					"%02d", pt, ptlim);
260 				continue;
261 			case 'j':
262 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
263 				continue;
264 			case 'k':
265 				/*
266 				** This used to be...
267 				**	_conv(t->tm_hour % 12 ?
268 				**		t->tm_hour % 12 : 12, 2, ' ');
269 				** ...and has been changed to the below to
270 				** match SunOS 4.1.1 and Arnold Robbins'
271 				** strftime version 3.0. That is, "%k" and
272 				** "%l" have been swapped.
273 				** (ado, 1993-05-24)
274 				*/
275 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
276 				continue;
277 #ifdef KITCHEN_SINK
278 			case 'K':
279 				/*
280 				** After all this time, still unclaimed!
281 				*/
282 				pt = _add("kitchen sink", pt, ptlim);
283 				continue;
284 #endif /* defined KITCHEN_SINK */
285 			case 'l':
286 				/*
287 				** This used to be...
288 				**	_conv(t->tm_hour, 2, ' ');
289 				** ...and has been changed to the below to
290 				** match SunOS 4.1.1 and Arnold Robbin's
291 				** strftime version 3.0. That is, "%k" and
292 				** "%l" have been swapped.
293 				** (ado, 1993-05-24)
294 				*/
295 				pt = _conv((t->tm_hour % 12) ?
296 					(t->tm_hour % 12) : 12,
297 					"%2d", pt, ptlim);
298 				continue;
299 			case 'M':
300 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
301 				continue;
302 			case 'm':
303 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
304 				continue;
305 			case 'n':
306 				pt = _add("\n", pt, ptlim);
307 				continue;
308 			case 'p':
309 				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
310 					Locale->pm :
311 					Locale->am,
312 					pt, ptlim);
313 				continue;
314 			case 'R':
315 				pt = _fmt("%H:%M", t, pt, ptlim, warnp);
316 				continue;
317 			case 'r':
318 				pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
319 				continue;
320 			case 'S':
321 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
322 				continue;
323 			case 's':
324 				{
325 					struct tm	tm;
326 					char		buf[INT_STRLEN_MAXIMUM(
327 								time_t) + 1];
328 					time_t		mkt;
329 
330 					tm = *t;
331 					mkt = mktime(&tm);
332 					if (TYPE_SIGNED(time_t))
333 						(void) snprintf(buf, sizeof buf,
334 						    "%ld", (long) mkt);
335 					else	(void) snprintf(buf, sizeof buf,
336 						    "%lu", (unsigned long) mkt);
337 					pt = _add(buf, pt, ptlim);
338 				}
339 				continue;
340 			case 'T':
341 				pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
342 				continue;
343 			case 't':
344 				pt = _add("\t", pt, ptlim);
345 				continue;
346 			case 'U':
347 				pt = _conv((t->tm_yday + DAYSPERWEEK -
348 					t->tm_wday) / DAYSPERWEEK,
349 					"%02d", pt, ptlim);
350 				continue;
351 			case 'u':
352 				/*
353 				** From Arnold Robbins' strftime version 3.0:
354 				** "ISO 8601: Weekday as a decimal number
355 				** [1 (Monday) - 7]"
356 				** (ado, 1993-05-24)
357 				*/
358 				pt = _conv((t->tm_wday == 0) ?
359 					DAYSPERWEEK : t->tm_wday,
360 					"%d", pt, ptlim);
361 				continue;
362 			case 'V':	/* ISO 8601 week number */
363 			case 'G':	/* ISO 8601 year (four digits) */
364 			case 'g':	/* ISO 8601 year (two digits) */
365 /*
366 ** From Arnold Robbins' strftime version 3.0: "the week number of the
367 ** year (the first Monday as the first day of week 1) as a decimal number
368 ** (01-53)."
369 ** (ado, 1993-05-24)
370 **
371 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
372 ** "Week 01 of a year is per definition the first week which has the
373 ** Thursday in this year, which is equivalent to the week which contains
374 ** the fourth day of January. In other words, the first week of a new year
375 ** is the week which has the majority of its days in the new year. Week 01
376 ** might also contain days from the previous year and the week before week
377 ** 01 of a year is the last week (52 or 53) of the previous year even if
378 ** it contains days from the new year. A week starts with Monday (day 1)
379 ** and ends with Sunday (day 7). For example, the first week of the year
380 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
381 ** (ado, 1996-01-02)
382 */
383 				{
384 					int	year;
385 					int	base;
386 					int	yday;
387 					int	wday;
388 					int	w;
389 
390 					year = t->tm_year;
391 					base = TM_YEAR_BASE;
392 					yday = t->tm_yday;
393 					wday = t->tm_wday;
394 					for ( ; ; ) {
395 						int	len;
396 						int	bot;
397 						int	top;
398 
399 						len = isleap_sum(year, base) ?
400 							DAYSPERLYEAR :
401 							DAYSPERNYEAR;
402 						/*
403 						** What yday (-3 ... 3) does
404 						** the ISO year begin on?
405 						*/
406 						bot = ((yday + 11 - wday) %
407 							DAYSPERWEEK) - 3;
408 						/*
409 						** What yday does the NEXT
410 						** ISO year begin on?
411 						*/
412 						top = bot -
413 							(len % DAYSPERWEEK);
414 						if (top < -3)
415 							top += DAYSPERWEEK;
416 						top += len;
417 						if (yday >= top) {
418 							++base;
419 							w = 1;
420 							break;
421 						}
422 						if (yday >= bot) {
423 							w = 1 + ((yday - bot) /
424 								DAYSPERWEEK);
425 							break;
426 						}
427 						--base;
428 						yday += isleap_sum(year, base) ?
429 							DAYSPERLYEAR :
430 							DAYSPERNYEAR;
431 					}
432 #ifdef XPG4_1994_04_09
433 					if ((w == 52 &&
434 						t->tm_mon == TM_JANUARY) ||
435 						(w == 1 &&
436 						t->tm_mon == TM_DECEMBER))
437 							w = 53;
438 #endif /* defined XPG4_1994_04_09 */
439 					if (*format == 'V')
440 						pt = _conv(w, "%02d",
441 							pt, ptlim);
442 					else if (*format == 'g') {
443 						*warnp = IN_ALL;
444 						pt = _yconv(year, base, 0, 1,
445 							pt, ptlim);
446 					} else	pt = _yconv(year, base, 1, 1,
447 							pt, ptlim);
448 				}
449 				continue;
450 			case 'v':
451 				/*
452 				** From Arnold Robbins' strftime version 3.0:
453 				** "date as dd-bbb-YYYY"
454 				** (ado, 1993-05-24)
455 				*/
456 				pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
457 				continue;
458 			case 'W':
459 				pt = _conv((t->tm_yday + DAYSPERWEEK -
460 					(t->tm_wday ?
461 					(t->tm_wday - 1) :
462 					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
463 					"%02d", pt, ptlim);
464 				continue;
465 			case 'w':
466 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
467 				continue;
468 			case 'X':
469 				pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
470 				continue;
471 			case 'x':
472 				{
473 				int	warn2 = IN_SOME;
474 
475 				pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
476 				if (warn2 == IN_ALL)
477 					warn2 = IN_THIS;
478 				if (warn2 > *warnp)
479 					*warnp = warn2;
480 				}
481 				continue;
482 			case 'y':
483 				*warnp = IN_ALL;
484 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
485 					pt, ptlim);
486 				continue;
487 			case 'Y':
488 				pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
489 					pt, ptlim);
490 				continue;
491 			case 'Z':
492 #ifdef TM_ZONE
493 				if (t->TM_ZONE != NULL)
494 					pt = _add(t->TM_ZONE, pt, ptlim);
495 				else
496 #endif /* defined TM_ZONE */
497 				if (t->tm_isdst >= 0)
498 					pt = _add(tzname[t->tm_isdst != 0],
499 						pt, ptlim);
500 				/*
501 				** C99 says that %Z must be replaced by the
502 				** empty string if the time zone is not
503 				** determinable.
504 				*/
505 				continue;
506 			case 'z':
507 				{
508 				int		diff;
509 				char const *	sign;
510 
511 				if (t->tm_isdst < 0)
512 					continue;
513 #ifdef TM_GMTOFF
514 				diff = t->TM_GMTOFF;
515 #else /* !defined TM_GMTOFF */
516 				/*
517 				** C99 says that the UTC offset must
518 				** be computed by looking only at
519 				** tm_isdst. This requirement is
520 				** incorrect, since it means the code
521 				** must rely on magic (in this case
522 				** altzone and timezone), and the
523 				** magic might not have the correct
524 				** offset. Doing things correctly is
525 				** tricky and requires disobeying C99;
526 				** see GNU C strftime for details.
527 				** For now, punt and conform to the
528 				** standard, even though it's incorrect.
529 				**
530 				** C99 says that %z must be replaced by the
531 				** empty string if the time zone is not
532 				** determinable, so output nothing if the
533 				** appropriate variables are not available.
534 				*/
535 				if (t->tm_isdst == 0)
536 #ifdef USG_COMPAT
537 					diff = -timezone;
538 #else /* !defined USG_COMPAT */
539 					continue;
540 #endif /* !defined USG_COMPAT */
541 				else
542 #ifdef ALTZONE
543 					diff = -altzone;
544 #else /* !defined ALTZONE */
545 					continue;
546 #endif /* !defined ALTZONE */
547 #endif /* !defined TM_GMTOFF */
548 				if (diff < 0) {
549 					sign = "-";
550 					diff = -diff;
551 				} else	sign = "+";
552 				pt = _add(sign, pt, ptlim);
553 				diff /= SECSPERMIN;
554 				diff = (diff / MINSPERHOUR) * 100 +
555 					(diff % MINSPERHOUR);
556 				pt = _conv(diff, "%04d", pt, ptlim);
557 				}
558 				continue;
559 			case '+':
560 				pt = _fmt(Locale->date_fmt, t, pt, ptlim,
561 					warnp);
562 				continue;
563 			case '%':
564 			/*
565 			** X311J/88-090 (4.12.3.5): if conversion char is
566 			** undefined, behavior is undefined. Print out the
567 			** character itself as printf(3) also does.
568 			*/
569 			default:
570 				break;
571 			}
572 		}
573 		if (pt == ptlim)
574 			break;
575 		*pt++ = *format;
576 	}
577 	return pt;
578 }
579 
580 static char *
581 _conv(n, format, pt, ptlim)
582 const int		n;
583 const char * const	format;
584 char * const		pt;
585 const char * const	ptlim;
586 {
587 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
588 
589 	(void) snprintf(buf, sizeof buf, format, n);
590 	return _add(buf, pt, ptlim);
591 }
592 
593 static char *
594 _add(str, pt, ptlim)
595 const char *		str;
596 char *			pt;
597 const char * const	ptlim;
598 {
599 	while (pt < ptlim && (*pt = *str++) != '\0')
600 		++pt;
601 	return pt;
602 }
603 
604 /*
605 ** POSIX and the C Standard are unclear or inconsistent about
606 ** what %C and %y do if the year is negative or exceeds 9999.
607 ** Use the convention that %C concatenated with %y yields the
608 ** same output as %Y, and that %Y contains at least 4 bytes,
609 ** with more only if necessary.
610 */
611 
612 static char *
613 _yconv(a, b, convert_top, convert_yy, pt, ptlim)
614 const int		a;
615 const int		b;
616 const int		convert_top;
617 const int		convert_yy;
618 char *			pt;
619 const char * const	ptlim;
620 {
621 	register int	lead;
622 	register int	trail;
623 
624 #define DIVISOR	100
625 	trail = a % DIVISOR + b % DIVISOR;
626 	lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
627 	trail %= DIVISOR;
628 	if (trail < 0 && lead > 0) {
629 		trail += DIVISOR;
630 		--lead;
631 	} else if (lead < 0 && trail > 0) {
632 		trail -= DIVISOR;
633 		++lead;
634 	}
635 	if (convert_top) {
636 		if (lead == 0 && trail < 0)
637 			pt = _add("-0", pt, ptlim);
638 		else	pt = _conv(lead, "%02d", pt, ptlim);
639 	}
640 	if (convert_yy)
641 		pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
642 	return pt;
643 }
644 
645 #ifdef LOCALE_HOME
646 static struct lc_time_T *
647 _loc(void)
648 {
649 	static const char	locale_home[] = LOCALE_HOME;
650 	static const char	lc_time[] = "LC_TIME";
651 	static char *		locale_buf;
652 
653 	int			fd;
654 	int			oldsun;	/* "...ain't got nothin' to do..." */
655 	int			len;
656 	char *			lbuf;
657 	char *			nlbuf;
658 	char *			name;
659 	char *			p;
660 	const char **		ap;
661 	const char *		plim;
662 	char			filename[FILENAME_MAX];
663 	struct stat		st;
664 	size_t			namesize;
665 	size_t			bufsize;
666 
667 	/*
668 	** Use localebuf.mon[0] to signal whether locale is already set up.
669 	*/
670 	if (localebuf.mon[0])
671 		return &localebuf;
672 	name = setlocale(LC_TIME, (char *) NULL);
673 	if (name == NULL || *name == '\0')
674 		goto no_locale;
675 	/*
676 	** If the locale name is the same as our cache, use the cache.
677 	*/
678 	lbuf = locale_buf;
679 	if (lbuf != NULL && strcmp(name, lbuf) == 0) {
680 		p = lbuf;
681 		for (ap = (const char **) &localebuf;
682 			ap < (const char **) (&localebuf + 1);
683 				++ap)
684 					*ap = p += strlen(p) + 1;
685 		return &localebuf;
686 	}
687 	/*
688 	** Slurp the locale file into the cache.
689 	*/
690 	namesize = strlen(name) + 1;
691 	if (sizeof filename <
692 		((sizeof locale_home) + namesize + (sizeof lc_time)))
693 			goto no_locale;
694 	oldsun = 0;
695 	len = snprintf(filename, sizeof filename, "%s/%s/%s", locale_home,
696 	    name, lc_time);
697 	if (len < 0 || len >= sizeof filename)
698 		goto no_locale;
699 	fd = open(filename, O_RDONLY);
700 	if (fd < 0) {
701 		/*
702 		** Old Sun systems have a different naming and data convention.
703 		*/
704 		oldsun = 1;
705 		len = snprintf(filename, sizeof filename, "%s/%s/%s",
706 			locale_home, lc_time, name);
707 		if (len < 0 || len >= sizeof filename)
708 			goto no_locale;
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 	nlbuf = (lbuf == NULL) ? malloc(bufsize) : realloc(lbuf, bufsize);
720 	if (nlbuf == NULL) {
721 		if (lbuf)
722 			free(lbuf);
723 		lbuf = NULL;
724 		goto bad_locale;
725 	}
726 	lbuf = nlbuf;
727 	(void) strlcpy(lbuf, name, bufsize);
728 	p = lbuf + namesize;
729 	plim = p + st.st_size;
730 	if (read(fd, p, (size_t) st.st_size) != st.st_size)
731 		goto bad_lbuf;
732 	if (close(fd) != 0)
733 		goto bad_lbuf;
734 	/*
735 	** Parse the locale file into localebuf.
736 	*/
737 	if (plim[-1] != '\n')
738 		goto bad_lbuf;
739 	for (ap = (const char **) &localebuf;
740 		ap < (const char **) (&localebuf + 1);
741 			++ap) {
742 				if (p == plim)
743 					goto bad_lbuf;
744 				*ap = p;
745 				while (*p != '\n')
746 					++p;
747 				*p++ = '\0';
748 	}
749 	if (oldsun) {
750 		/*
751 		** SunOS 4 used an obsolescent format; see localdtconv(3).
752 		** c_fmt had the ``short format for dates and times together''
753 		** (SunOS 4 date, "%a %b %e %T %Z %Y" in the C locale);
754 		** date_fmt had the ``long format for dates''
755 		** (SunOS 4 strftime %C, "%A, %B %e, %Y" in the C locale).
756 		** Discard the latter in favor of the former.
757 		*/
758 		localebuf.date_fmt = localebuf.c_fmt;
759 	}
760 	/*
761 	** Record the successful parse in the cache.
762 	*/
763 	locale_buf = lbuf;
764 
765 	return &localebuf;
766 
767 bad_lbuf:
768 	free(lbuf);
769 bad_locale:
770 	(void) close(fd);
771 no_locale:
772 	localebuf = C_time_locale;
773 	locale_buf = NULL;
774 	return &localebuf;
775 }
776 #endif /* defined LOCALE_HOME */
777