xref: /netbsd-src/lib/libc/time/localtime.c (revision fdecd6a253f999ae92b139670d9e15cc9df4497c)
1 /*	$NetBSD: localtime.c,v 1.10 1997/06/18 01:12:45 jtc Exp $	*/
2 
3 /*
4 ** This file is in the public domain, so clarified as of
5 ** 1996-06-05 by Arthur David Olson (arthur_david_olson@nih.gov).
6 */
7 
8 #ifndef lint
9 #ifndef NOID
10 static char	elsieid[] = "@(#)localtime.c	7.61";
11 #endif /* !defined NOID */
12 #endif /* !defined lint */
13 
14 /*
15 ** Leap second handling from Bradley White (bww@k.gp.cs.cmu.edu).
16 ** POSIX-style TZ environment variable handling from Guy Harris
17 ** (guy@auspex.com).
18 */
19 
20 /*LINTLIBRARY*/
21 
22 #include "private.h"
23 #include "tzfile.h"
24 #include "fcntl.h"
25 
26 /*
27 ** SunOS 4.1.1 headers lack O_BINARY.
28 */
29 
30 #ifdef O_BINARY
31 #define OPEN_MODE	(O_RDONLY | O_BINARY)
32 #endif /* defined O_BINARY */
33 #ifndef O_BINARY
34 #define OPEN_MODE	O_RDONLY
35 #endif /* !defined O_BINARY */
36 
37 #ifndef WILDABBR
38 /*
39 ** Someone might make incorrect use of a time zone abbreviation:
40 **	1.	They might reference tzname[0] before calling tzset (explicitly
41 **		or implicitly).
42 **	2.	They might reference tzname[1] before calling tzset (explicitly
43 **		or implicitly).
44 **	3.	They might reference tzname[1] after setting to a time zone
45 **		in which Daylight Saving Time is never observed.
46 **	4.	They might reference tzname[0] after setting to a time zone
47 **		in which Standard Time is never observed.
48 **	5.	They might reference tm.TM_ZONE after calling offtime.
49 ** What's best to do in the above cases is open to debate;
50 ** for now, we just set things up so that in any of the five cases
51 ** WILDABBR is used.  Another possibility:  initialize tzname[0] to the
52 ** string "tzname[0] used before set", and similarly for the other cases.
53 ** And another:  initialize tzname[0] to "ERA", with an explanation in the
54 ** manual page of what this "time zone abbreviation" means (doing this so
55 ** that tzname[0] has the "normal" length of three characters).
56 */
57 #define WILDABBR	"   "
58 #endif /* !defined WILDABBR */
59 
60 static char		wildabbr[] = "WILDABBR";
61 
62 static const char	gmt[] = "GMT";
63 
64 struct ttinfo {				/* time type information */
65 	long		tt_gmtoff;	/* GMT offset in seconds */
66 	int		tt_isdst;	/* used to set tm_isdst */
67 	int		tt_abbrind;	/* abbreviation list index */
68 	int		tt_ttisstd;	/* TRUE if transition is std time */
69 	int		tt_ttisgmt;	/* TRUE if transition is GMT */
70 };
71 
72 struct lsinfo {				/* leap second information */
73 	time_t		ls_trans;	/* transition time */
74 	long		ls_corr;	/* correction to apply */
75 };
76 
77 #define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))
78 
79 #ifdef TZNAME_MAX
80 #define MY_TZNAME_MAX	TZNAME_MAX
81 #endif /* defined TZNAME_MAX */
82 #ifndef TZNAME_MAX
83 #define MY_TZNAME_MAX	255
84 #endif /* !defined TZNAME_MAX */
85 
86 struct state {
87 	int		leapcnt;
88 	int		timecnt;
89 	int		typecnt;
90 	int		charcnt;
91 	time_t		ats[TZ_MAX_TIMES];
92 	unsigned char	types[TZ_MAX_TIMES];
93 	struct ttinfo	ttis[TZ_MAX_TYPES];
94 	char		chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof gmt),
95 				(2 * (MY_TZNAME_MAX + 1)))];
96 	struct lsinfo	lsis[TZ_MAX_LEAPS];
97 };
98 
99 struct rule {
100 	int		r_type;		/* type of rule--see below */
101 	int		r_day;		/* day number of rule */
102 	int		r_week;		/* week number of rule */
103 	int		r_mon;		/* month number of rule */
104 	long		r_time;		/* transition time of rule */
105 };
106 
107 #define JULIAN_DAY		0	/* Jn - Julian day */
108 #define DAY_OF_YEAR		1	/* n - day of year */
109 #define MONTH_NTH_DAY_OF_WEEK	2	/* Mm.n.d - month, week, day of week */
110 
111 /*
112 ** Prototypes for static functions.
113 */
114 
115 static long		detzcode P((const char * codep));
116 static const char *	getzname P((const char * strp));
117 static const char *	getnum P((const char * strp, int * nump, int min,
118 				int max));
119 static const char *	getsecs P((const char * strp, long * secsp));
120 static const char *	getoffset P((const char * strp, long * offsetp));
121 static const char *	getrule P((const char * strp, struct rule * rulep));
122 static void		gmtload P((struct state * sp));
123 static void		gmtsub P((const time_t * timep, long offset,
124 				struct tm * tmp));
125 static void		localsub P((const time_t * timep, long offset,
126 				struct tm * tmp));
127 static int		increment_overflow P((int * number, int delta));
128 static int		normalize_overflow P((int * tensptr, int * unitsptr,
129 				int base));
130 static void		settzname P((void));
131 static time_t		time1 P((struct tm * tmp,
132 				void(*funcp) P((const time_t *,
133 				long, struct tm *)),
134 				long offset));
135 static time_t		time2 P((struct tm *tmp,
136 				void(*funcp) P((const time_t *,
137 				long, struct tm*)),
138 				long offset, int * okayp));
139 static void		timesub P((const time_t * timep, long offset,
140 				const struct state * sp, struct tm * tmp));
141 static int		tmcomp P((const struct tm * atmp,
142 				const struct tm * btmp));
143 static time_t		transtime P((time_t janfirst, int year,
144 				const struct rule * rulep, long offset));
145 static int		tzload P((const char * name, struct state * sp));
146 static int		tzparse P((const char * name, struct state * sp,
147 				int lastditch));
148 
149 #ifdef ALL_STATE
150 static struct state *	lclptr;
151 static struct state *	gmtptr;
152 #endif /* defined ALL_STATE */
153 
154 #ifndef ALL_STATE
155 static struct state	lclmem;
156 static struct state	gmtmem;
157 #define lclptr		(&lclmem)
158 #define gmtptr		(&gmtmem)
159 #endif /* State Farm */
160 
161 #ifndef TZ_STRLEN_MAX
162 #define TZ_STRLEN_MAX 255
163 #endif /* !defined TZ_STRLEN_MAX */
164 
165 static char		lcl_TZname[TZ_STRLEN_MAX + 1];
166 static int		lcl_is_set;
167 static int		gmt_is_set;
168 
169 char *			tzname[2] = {
170 	wildabbr,
171 	wildabbr
172 };
173 
174 /*
175 ** Section 4.12.3 of X3.159-1989 requires that
176 **	Except for the strftime function, these functions [asctime,
177 **	ctime, gmtime, localtime] return values in one of two static
178 **	objects: a broken-down time structure and an array of char.
179 ** Thanks to Paul Eggert (eggert@twinsun.com) for noting this.
180 */
181 
182 static struct tm	tm;
183 
184 #ifdef USG_COMPAT
185 time_t			timezone = 0;
186 int			daylight = 0;
187 #endif /* defined USG_COMPAT */
188 
189 #ifdef ALTZONE
190 time_t			altzone = 0;
191 #endif /* defined ALTZONE */
192 
193 static long
194 detzcode(codep)
195 const char * const	codep;
196 {
197 	register long	result;
198 
199 	/*
200         ** The first character must be sign extended on systems with >32bit
201         ** longs.  This was solved differently in the master tzcode sources
202         ** (the fix first appeared in tzcode95c.tar.gz).  But I believe
203 	** that this implementation is superior.
204         */
205 
206 #ifdef __STDC__
207 #define SIGN_EXTEND_CHAR(x)	((signed char) x)
208 #else
209 #define SIGN_EXTEND_CHAR(x)	((x & 0x80) ? ((~0 << 8) | x) : x)
210 #endif
211 
212 	result = (SIGN_EXTEND_CHAR(codep[0]) << 24) \
213 	       | (codep[1] & 0xff) << 16 \
214 	       | (codep[2] & 0xff) << 8
215 	       | (codep[3] & 0xff);
216 	return result;
217 }
218 
219 static void
220 settzname P((void))
221 {
222 	register struct state * const	sp = lclptr;
223 	register int			i;
224 
225 	tzname[0] = wildabbr;
226 	tzname[1] = wildabbr;
227 #ifdef USG_COMPAT
228 	daylight = 0;
229 	timezone = 0;
230 #endif /* defined USG_COMPAT */
231 #ifdef ALTZONE
232 	altzone = 0;
233 #endif /* defined ALTZONE */
234 #ifdef ALL_STATE
235 	if (sp == NULL) {
236 		tzname[0] = tzname[1] = gmt;
237 		return;
238 	}
239 #endif /* defined ALL_STATE */
240 	for (i = 0; i < sp->typecnt; ++i) {
241 		register const struct ttinfo * const	ttisp = &sp->ttis[i];
242 
243 		tzname[ttisp->tt_isdst] =
244 			&sp->chars[ttisp->tt_abbrind];
245 #ifdef USG_COMPAT
246 		if (ttisp->tt_isdst)
247 			daylight = 1;
248 		if (i == 0 || !ttisp->tt_isdst)
249 			timezone = -(ttisp->tt_gmtoff);
250 #endif /* defined USG_COMPAT */
251 #ifdef ALTZONE
252 		if (i == 0 || ttisp->tt_isdst)
253 			altzone = -(ttisp->tt_gmtoff);
254 #endif /* defined ALTZONE */
255 	}
256 	/*
257 	** And to get the latest zone names into tzname. . .
258 	*/
259 	for (i = 0; i < sp->timecnt; ++i) {
260 		register const struct ttinfo * const	ttisp =
261 							&sp->ttis[
262 								sp->types[i]];
263 
264 		tzname[ttisp->tt_isdst] =
265 			&sp->chars[ttisp->tt_abbrind];
266 	}
267 }
268 
269 static int
270 tzload(name, sp)
271 register const char *		name;
272 register struct state * const	sp;
273 {
274 	register const char *	p;
275 	register int		i;
276 	register int		fid;
277 
278 	if (name == NULL && (name = TZDEFAULT) == NULL)
279 		return -1;
280 
281 	{
282 		register int	doaccess;
283 		/*
284 		** Section 4.9.1 of the C standard says that
285 		** "FILENAME_MAX expands to an integral constant expression
286 		** that is the size needed for an array of char large enough
287 		** to hold the longest file name string that the implementation
288 		** guarantees can be opened."
289 		*/
290 		char		fullname[FILENAME_MAX + 1];
291 
292 		if (name[0] == ':')
293 			++name;
294 		doaccess = name[0] == '/';
295 		if (!doaccess) {
296 			if ((p = TZDIR) == NULL)
297 				return -1;
298 			if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
299 				return -1;
300 			(void) strcpy(fullname, p);	/* XXX strcpy is safe */
301 			(void) strcat(fullname, "/");	/* XXX strcat is safe */
302 			(void) strcat(fullname, name);	/* XXX strcat is safe */
303 			/*
304 			** Set doaccess if '.' (as in "../") shows up in name.
305 			*/
306 			if (strchr(name, '.') != NULL)
307 				doaccess = TRUE;
308 			name = fullname;
309 		}
310 		if (doaccess && access(name, R_OK) != 0)
311 			return -1;
312 		/*
313 		 * XXX potential security problem here if user of a set-id
314 		 * program has set TZ (which is passed in as name) here,
315 		 * and uses a race condition trick to defeat the access(2)
316 		 * above.
317 		 */
318 		if ((fid = open(name, OPEN_MODE)) == -1)
319 			return -1;
320 	}
321 	{
322 		struct tzhead *	tzhp;
323 		char		buf[sizeof *sp + sizeof *tzhp];
324 		int		ttisstdcnt;
325 		int		ttisgmtcnt;
326 
327 		i = read(fid, buf, sizeof buf);
328 		if (close(fid) != 0)
329 			return -1;
330 		p = buf;
331 		p += sizeof tzhp->tzh_reserved;
332 		ttisstdcnt = (int) detzcode(p);
333 		p += 4;
334 		ttisgmtcnt = (int) detzcode(p);
335 		p += 4;
336 		sp->leapcnt = (int) detzcode(p);
337 		p += 4;
338 		sp->timecnt = (int) detzcode(p);
339 		p += 4;
340 		sp->typecnt = (int) detzcode(p);
341 		p += 4;
342 		sp->charcnt = (int) detzcode(p);
343 		p += 4;
344 		if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
345 			sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
346 			sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
347 			sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
348 			(ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
349 			(ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
350 				return -1;
351 		if (i - (p - buf) < sp->timecnt * 4 +	/* ats */
352 			sp->timecnt +			/* types */
353 			sp->typecnt * (4 + 2) +		/* ttinfos */
354 			sp->charcnt +			/* chars */
355 			sp->leapcnt * (4 + 4) +		/* lsinfos */
356 			ttisstdcnt +			/* ttisstds */
357 			ttisgmtcnt)			/* ttisgmts */
358 				return -1;
359 		for (i = 0; i < sp->timecnt; ++i) {
360 			sp->ats[i] = detzcode(p);
361 			p += 4;
362 		}
363 		for (i = 0; i < sp->timecnt; ++i) {
364 			sp->types[i] = (unsigned char) *p++;
365 			if (sp->types[i] >= sp->typecnt)
366 				return -1;
367 		}
368 		for (i = 0; i < sp->typecnt; ++i) {
369 			register struct ttinfo *	ttisp;
370 
371 			ttisp = &sp->ttis[i];
372 			ttisp->tt_gmtoff = detzcode(p);
373 			p += 4;
374 			ttisp->tt_isdst = (unsigned char) *p++;
375 			if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
376 				return -1;
377 			ttisp->tt_abbrind = (unsigned char) *p++;
378 			if (ttisp->tt_abbrind < 0 ||
379 				ttisp->tt_abbrind > sp->charcnt)
380 					return -1;
381 		}
382 		for (i = 0; i < sp->charcnt; ++i)
383 			sp->chars[i] = *p++;
384 		sp->chars[i] = '\0';	/* ensure '\0' at end */
385 		for (i = 0; i < sp->leapcnt; ++i) {
386 			register struct lsinfo *	lsisp;
387 
388 			lsisp = &sp->lsis[i];
389 			lsisp->ls_trans = detzcode(p);
390 			p += 4;
391 			lsisp->ls_corr = detzcode(p);
392 			p += 4;
393 		}
394 		for (i = 0; i < sp->typecnt; ++i) {
395 			register struct ttinfo *	ttisp;
396 
397 			ttisp = &sp->ttis[i];
398 			if (ttisstdcnt == 0)
399 				ttisp->tt_ttisstd = FALSE;
400 			else {
401 				ttisp->tt_ttisstd = *p++;
402 				if (ttisp->tt_ttisstd != TRUE &&
403 					ttisp->tt_ttisstd != FALSE)
404 						return -1;
405 			}
406 		}
407 		for (i = 0; i < sp->typecnt; ++i) {
408 			register struct ttinfo *	ttisp;
409 
410 			ttisp = &sp->ttis[i];
411 			if (ttisgmtcnt == 0)
412 				ttisp->tt_ttisgmt = FALSE;
413 			else {
414 				ttisp->tt_ttisgmt = *p++;
415 				if (ttisp->tt_ttisgmt != TRUE &&
416 					ttisp->tt_ttisgmt != FALSE)
417 						return -1;
418 			}
419 		}
420 	}
421 	return 0;
422 }
423 
424 static const int	mon_lengths[2][MONSPERYEAR] = {
425 	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
426 	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
427 };
428 
429 static const int	year_lengths[2] = {
430 	DAYSPERNYEAR, DAYSPERLYEAR
431 };
432 
433 /*
434 ** Given a pointer into a time zone string, scan until a character that is not
435 ** a valid character in a zone name is found.  Return a pointer to that
436 ** character.
437 */
438 
439 static const char *
440 getzname(strp)
441 register const char *	strp;
442 {
443 	register char	c;
444 
445 	while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
446 		c != '+')
447 			++strp;
448 	return strp;
449 }
450 
451 /*
452 ** Given a pointer into a time zone string, extract a number from that string.
453 ** Check that the number is within a specified range; if it is not, return
454 ** NULL.
455 ** Otherwise, return a pointer to the first character not part of the number.
456 */
457 
458 static const char *
459 getnum(strp, nump, min, max)
460 register const char *	strp;
461 int * const		nump;
462 const int		min;
463 const int		max;
464 {
465 	register char	c;
466 	register int	num;
467 
468 	if (strp == NULL || !is_digit(c = *strp))
469 		return NULL;
470 	num = 0;
471 	do {
472 		num = num * 10 + (c - '0');
473 		if (num > max)
474 			return NULL;	/* illegal value */
475 		c = *++strp;
476 	} while (is_digit(c));
477 	if (num < min)
478 		return NULL;		/* illegal value */
479 	*nump = num;
480 	return strp;
481 }
482 
483 /*
484 ** Given a pointer into a time zone string, extract a number of seconds,
485 ** in hh[:mm[:ss]] form, from the string.
486 ** If any error occurs, return NULL.
487 ** Otherwise, return a pointer to the first character not part of the number
488 ** of seconds.
489 */
490 
491 static const char *
492 getsecs(strp, secsp)
493 register const char *	strp;
494 long * const		secsp;
495 {
496 	int	num;
497 
498 	/*
499 	** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
500 	** "M10.4.6/26", which does not conform to Posix,
501 	** but which specifies the equivalent of
502 	** ``02:00 on the first Sunday on or after 23 Oct''.
503 	*/
504 	strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
505 	if (strp == NULL)
506 		return NULL;
507 	*secsp = num * (long) SECSPERHOUR;
508 	if (*strp == ':') {
509 		++strp;
510 		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
511 		if (strp == NULL)
512 			return NULL;
513 		*secsp += num * SECSPERMIN;
514 		if (*strp == ':') {
515 			++strp;
516 			/* `SECSPERMIN' allows for leap seconds.  */
517 			strp = getnum(strp, &num, 0, SECSPERMIN);
518 			if (strp == NULL)
519 				return NULL;
520 			*secsp += num;
521 		}
522 	}
523 	return strp;
524 }
525 
526 /*
527 ** Given a pointer into a time zone string, extract an offset, in
528 ** [+-]hh[:mm[:ss]] form, from the string.
529 ** If any error occurs, return NULL.
530 ** Otherwise, return a pointer to the first character not part of the time.
531 */
532 
533 static const char *
534 getoffset(strp, offsetp)
535 register const char *	strp;
536 long * const		offsetp;
537 {
538 	register int	neg = 0;
539 
540 	if (*strp == '-') {
541 		neg = 1;
542 		++strp;
543 	} else if (*strp == '+')
544 		++strp;
545 	strp = getsecs(strp, offsetp);
546 	if (strp == NULL)
547 		return NULL;		/* illegal time */
548 	if (neg)
549 		*offsetp = -*offsetp;
550 	return strp;
551 }
552 
553 /*
554 ** Given a pointer into a time zone string, extract a rule in the form
555 ** date[/time].  See POSIX section 8 for the format of "date" and "time".
556 ** If a valid rule is not found, return NULL.
557 ** Otherwise, return a pointer to the first character not part of the rule.
558 */
559 
560 static const char *
561 getrule(strp, rulep)
562 const char *			strp;
563 register struct rule * const	rulep;
564 {
565 	if (*strp == 'J') {
566 		/*
567 		** Julian day.
568 		*/
569 		rulep->r_type = JULIAN_DAY;
570 		++strp;
571 		strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
572 	} else if (*strp == 'M') {
573 		/*
574 		** Month, week, day.
575 		*/
576 		rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
577 		++strp;
578 		strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
579 		if (strp == NULL)
580 			return NULL;
581 		if (*strp++ != '.')
582 			return NULL;
583 		strp = getnum(strp, &rulep->r_week, 1, 5);
584 		if (strp == NULL)
585 			return NULL;
586 		if (*strp++ != '.')
587 			return NULL;
588 		strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
589 	} else if (is_digit(*strp)) {
590 		/*
591 		** Day of year.
592 		*/
593 		rulep->r_type = DAY_OF_YEAR;
594 		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
595 	} else	return NULL;		/* invalid format */
596 	if (strp == NULL)
597 		return NULL;
598 	if (*strp == '/') {
599 		/*
600 		** Time specified.
601 		*/
602 		++strp;
603 		strp = getsecs(strp, &rulep->r_time);
604 	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
605 	return strp;
606 }
607 
608 /*
609 ** Given the Epoch-relative time of January 1, 00:00:00 GMT, in a year, the
610 ** year, a rule, and the offset from GMT at the time that rule takes effect,
611 ** calculate the Epoch-relative time that rule takes effect.
612 */
613 
614 static time_t
615 transtime(janfirst, year, rulep, offset)
616 const time_t				janfirst;
617 const int				year;
618 register const struct rule * const	rulep;
619 const long				offset;
620 {
621 	register int	leapyear;
622 	register time_t	value;
623 	register int	i;
624 	int		d, m1, yy0, yy1, yy2, dow;
625 
626 	INITIALIZE(value);
627 	leapyear = isleap(year);
628 	switch (rulep->r_type) {
629 
630 	case JULIAN_DAY:
631 		/*
632 		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
633 		** years.
634 		** In non-leap years, or if the day number is 59 or less, just
635 		** add SECSPERDAY times the day number-1 to the time of
636 		** January 1, midnight, to get the day.
637 		*/
638 		value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
639 		if (leapyear && rulep->r_day >= 60)
640 			value += SECSPERDAY;
641 		break;
642 
643 	case DAY_OF_YEAR:
644 		/*
645 		** n - day of year.
646 		** Just add SECSPERDAY times the day number to the time of
647 		** January 1, midnight, to get the day.
648 		*/
649 		value = janfirst + rulep->r_day * SECSPERDAY;
650 		break;
651 
652 	case MONTH_NTH_DAY_OF_WEEK:
653 		/*
654 		** Mm.n.d - nth "dth day" of month m.
655 		*/
656 		value = janfirst;
657 		for (i = 0; i < rulep->r_mon - 1; ++i)
658 			value += mon_lengths[leapyear][i] * SECSPERDAY;
659 
660 		/*
661 		** Use Zeller's Congruence to get day-of-week of first day of
662 		** month.
663 		*/
664 		m1 = (rulep->r_mon + 9) % 12 + 1;
665 		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
666 		yy1 = yy0 / 100;
667 		yy2 = yy0 % 100;
668 		dow = ((26 * m1 - 2) / 10 +
669 			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
670 		if (dow < 0)
671 			dow += DAYSPERWEEK;
672 
673 		/*
674 		** "dow" is the day-of-week of the first day of the month.  Get
675 		** the day-of-month (zero-origin) of the first "dow" day of the
676 		** month.
677 		*/
678 		d = rulep->r_day - dow;
679 		if (d < 0)
680 			d += DAYSPERWEEK;
681 		for (i = 1; i < rulep->r_week; ++i) {
682 			if (d + DAYSPERWEEK >=
683 				mon_lengths[leapyear][rulep->r_mon - 1])
684 					break;
685 			d += DAYSPERWEEK;
686 		}
687 
688 		/*
689 		** "d" is the day-of-month (zero-origin) of the day we want.
690 		*/
691 		value += d * SECSPERDAY;
692 		break;
693 	}
694 
695 	/*
696 	** "value" is the Epoch-relative time of 00:00:00 GMT on the day in
697 	** question.  To get the Epoch-relative time of the specified local
698 	** time on that day, add the transition time and the current offset
699 	** from GMT.
700 	*/
701 	return value + rulep->r_time + offset;
702 }
703 
704 /*
705 ** Given a POSIX section 8-style TZ string, fill in the rule tables as
706 ** appropriate.
707 */
708 
709 static int
710 tzparse(name, sp, lastditch)
711 const char *			name;
712 register struct state * const	sp;
713 const int			lastditch;
714 {
715 	const char *			stdname;
716 	const char *			dstname;
717 	size_t				stdlen;
718 	size_t				dstlen;
719 	long				stdoffset;
720 	long				dstoffset;
721 	register time_t *		atp;
722 	register unsigned char *	typep;
723 	register char *			cp;
724 	register int			load_result;
725 
726 	INITIALIZE(dstname);
727 	stdname = name;
728 	if (lastditch) {
729 		stdlen = strlen(name);	/* length of standard zone name */
730 		name += stdlen;
731 		if (stdlen >= sizeof sp->chars)
732 			stdlen = (sizeof sp->chars) - 1;
733 		stdoffset = 0;
734 	} else {
735 		name = getzname(name);
736 		stdlen = name - stdname;
737 		if (stdlen < 3)
738 			return -1;
739 		if (*name == '\0')
740 			return -1;
741 		name = getoffset(name, &stdoffset);
742 		if (name == NULL)
743 			return -1;
744 	}
745 	load_result = tzload(TZDEFRULES, sp);
746 	if (load_result != 0)
747 		sp->leapcnt = 0;		/* so, we're off a little */
748 	if (*name != '\0') {
749 		dstname = name;
750 		name = getzname(name);
751 		dstlen = name - dstname;	/* length of DST zone name */
752 		if (dstlen < 3)
753 			return -1;
754 		if (*name != '\0' && *name != ',' && *name != ';') {
755 			name = getoffset(name, &dstoffset);
756 			if (name == NULL)
757 				return -1;
758 		} else	dstoffset = stdoffset - SECSPERHOUR;
759 		if (*name == ',' || *name == ';') {
760 			struct rule	start;
761 			struct rule	end;
762 			register int	year;
763 			register time_t	janfirst;
764 			time_t		starttime;
765 			time_t		endtime;
766 
767 			++name;
768 			if ((name = getrule(name, &start)) == NULL)
769 				return -1;
770 			if (*name++ != ',')
771 				return -1;
772 			if ((name = getrule(name, &end)) == NULL)
773 				return -1;
774 			if (*name != '\0')
775 				return -1;
776 			sp->typecnt = 2;	/* standard time and DST */
777 			/*
778 			** Two transitions per year, from EPOCH_YEAR to 2037.
779 			*/
780 			sp->timecnt = 2 * (2037 - EPOCH_YEAR + 1);
781 			if (sp->timecnt > TZ_MAX_TIMES)
782 				return -1;
783 			sp->ttis[0].tt_gmtoff = -dstoffset;
784 			sp->ttis[0].tt_isdst = 1;
785 			sp->ttis[0].tt_abbrind = stdlen + 1;
786 			sp->ttis[1].tt_gmtoff = -stdoffset;
787 			sp->ttis[1].tt_isdst = 0;
788 			sp->ttis[1].tt_abbrind = 0;
789 			atp = sp->ats;
790 			typep = sp->types;
791 			janfirst = 0;
792 			for (year = EPOCH_YEAR; year <= 2037; ++year) {
793 				starttime = transtime(janfirst, year, &start,
794 					stdoffset);
795 				endtime = transtime(janfirst, year, &end,
796 					dstoffset);
797 				if (starttime > endtime) {
798 					*atp++ = endtime;
799 					*typep++ = 1;	/* DST ends */
800 					*atp++ = starttime;
801 					*typep++ = 0;	/* DST begins */
802 				} else {
803 					*atp++ = starttime;
804 					*typep++ = 0;	/* DST begins */
805 					*atp++ = endtime;
806 					*typep++ = 1;	/* DST ends */
807 				}
808 				janfirst += year_lengths[isleap(year)] *
809 					SECSPERDAY;
810 			}
811 		} else {
812 			register long	theirstdoffset;
813 			register long	theirdstoffset;
814 			register long	theiroffset;
815 			register int	isdst;
816 			register int	i;
817 			register int	j;
818 
819 			if (*name != '\0')
820 				return -1;
821 			if (load_result != 0)
822 				return -1;
823 			/*
824 			** Initial values of theirstdoffset and theirdstoffset.
825 			*/
826 			theirstdoffset = 0;
827 			for (i = 0; i < sp->timecnt; ++i) {
828 				j = sp->types[i];
829 				if (!sp->ttis[j].tt_isdst) {
830 					theirstdoffset =
831 						-sp->ttis[j].tt_gmtoff;
832 					break;
833 				}
834 			}
835 			theirdstoffset = 0;
836 			for (i = 0; i < sp->timecnt; ++i) {
837 				j = sp->types[i];
838 				if (sp->ttis[j].tt_isdst) {
839 					theirdstoffset =
840 						-sp->ttis[j].tt_gmtoff;
841 					break;
842 				}
843 			}
844 			/*
845 			** Initially we're assumed to be in standard time.
846 			*/
847 			isdst = FALSE;
848 			theiroffset = theirstdoffset;
849 			/*
850 			** Now juggle transition times and types
851 			** tracking offsets as you do.
852 			*/
853 			for (i = 0; i < sp->timecnt; ++i) {
854 				j = sp->types[i];
855 				sp->types[i] = sp->ttis[j].tt_isdst;
856 				if (sp->ttis[j].tt_ttisgmt) {
857 					/* No adjustment to transition time */
858 				} else {
859 					/*
860 					** If summer time is in effect, and the
861 					** transition time was not specified as
862 					** standard time, add the summer time
863 					** offset to the transition time;
864 					** otherwise, add the standard time
865 					** offset to the transition time.
866 					*/
867 					/*
868 					** Transitions from DST to DDST
869 					** will effectively disappear since
870 					** POSIX provides for only one DST
871 					** offset.
872 					*/
873 					if (isdst && !sp->ttis[j].tt_ttisstd) {
874 						sp->ats[i] += dstoffset -
875 							theirdstoffset;
876 					} else {
877 						sp->ats[i] += stdoffset -
878 							theirstdoffset;
879 					}
880 				}
881 				theiroffset = -sp->ttis[j].tt_gmtoff;
882 				if (sp->ttis[j].tt_isdst)
883 					theirdstoffset = theiroffset;
884 				else	theirstdoffset = theiroffset;
885 			}
886 			/*
887 			** Finally, fill in ttis.
888 			** ttisstd and ttisgmt need not be handled.
889 			*/
890 			sp->ttis[0].tt_gmtoff = -stdoffset;
891 			sp->ttis[0].tt_isdst = FALSE;
892 			sp->ttis[0].tt_abbrind = 0;
893 			sp->ttis[1].tt_gmtoff = -dstoffset;
894 			sp->ttis[1].tt_isdst = TRUE;
895 			sp->ttis[1].tt_abbrind = stdlen + 1;
896 			sp->typecnt = 2;
897 		}
898 	} else {
899 		dstlen = 0;
900 		sp->typecnt = 1;		/* only standard time */
901 		sp->timecnt = 0;
902 		sp->ttis[0].tt_gmtoff = -stdoffset;
903 		sp->ttis[0].tt_isdst = 0;
904 		sp->ttis[0].tt_abbrind = 0;
905 	}
906 	sp->charcnt = stdlen + 1;
907 	if (dstlen != 0)
908 		sp->charcnt += dstlen + 1;
909 	if ((size_t) sp->charcnt > sizeof sp->chars)
910 		return -1;
911 	cp = sp->chars;
912 	(void) strncpy(cp, stdname, stdlen);
913 	cp += stdlen;
914 	*cp++ = '\0';
915 	if (dstlen != 0) {
916 		(void) strncpy(cp, dstname, dstlen);
917 		*(cp + dstlen) = '\0';
918 	}
919 	return 0;
920 }
921 
922 static void
923 gmtload(sp)
924 struct state * const	sp;
925 {
926 	if (tzload(gmt, sp) != 0)
927 		(void) tzparse(gmt, sp, TRUE);
928 }
929 
930 #ifndef STD_INSPIRED
931 /*
932 ** A non-static declaration of tzsetwall in a system header file
933 ** may cause a warning about this upcoming static declaration...
934 */
935 static
936 #endif /* !defined STD_INSPIRED */
937 void
938 tzsetwall P((void))
939 {
940 	if (lcl_is_set < 0)
941 		return;
942 	lcl_is_set = -1;
943 
944 #ifdef ALL_STATE
945 	if (lclptr == NULL) {
946 		lclptr = (struct state *) malloc(sizeof *lclptr);
947 		if (lclptr == NULL) {
948 			settzname();	/* all we can do */
949 			return;
950 		}
951 	}
952 #endif /* defined ALL_STATE */
953 	if (tzload((char *) NULL, lclptr) != 0)
954 		gmtload(lclptr);
955 	settzname();
956 }
957 
958 void
959 tzset P((void))
960 {
961 	register const char *	name;
962 
963 	name = getenv("TZ");
964 	if (name == NULL) {
965 		tzsetwall();
966 		return;
967 	}
968 
969 	if (lcl_is_set > 0  &&  strcmp(lcl_TZname, name) == 0)
970 		return;
971 	lcl_is_set = (strlen(name) < sizeof(lcl_TZname));
972 	if (lcl_is_set)
973 		(void)strncpy(lcl_TZname, name, sizeof(lcl_TZname) - 1);
974 
975 #ifdef ALL_STATE
976 	if (lclptr == NULL) {
977 		lclptr = (struct state *) malloc(sizeof *lclptr);
978 		if (lclptr == NULL) {
979 			settzname();	/* all we can do */
980 			return;
981 		}
982 	}
983 #endif /* defined ALL_STATE */
984 	if (*name == '\0') {
985 		/*
986 		** User wants it fast rather than right.
987 		*/
988 		lclptr->leapcnt = 0;		/* so, we're off a little */
989 		lclptr->timecnt = 0;
990 		lclptr->ttis[0].tt_gmtoff = 0;
991 		lclptr->ttis[0].tt_abbrind = 0;
992 		(void)strncpy(lclptr->chars, gmt, sizeof(lclptr->chars) - 1);
993 	} else if (tzload(name, lclptr) != 0)
994 		if (name[0] == ':' || tzparse(name, lclptr, FALSE) != 0)
995 			(void) gmtload(lclptr);
996 	settzname();
997 }
998 
999 /*
1000 ** The easy way to behave "as if no library function calls" localtime
1001 ** is to not call it--so we drop its guts into "localsub", which can be
1002 ** freely called.  (And no, the PANS doesn't require the above behavior--
1003 ** but it *is* desirable.)
1004 **
1005 ** The unused offset argument is for the benefit of mktime variants.
1006 */
1007 
1008 /*ARGSUSED*/
1009 static void
1010 localsub(timep, offset, tmp)
1011 const time_t * const	timep;
1012 const long		offset;
1013 struct tm * const	tmp;
1014 {
1015 	register struct state *		sp;
1016 	register const struct ttinfo *	ttisp;
1017 	register int			i;
1018 	const time_t			t = *timep;
1019 
1020 	sp = lclptr;
1021 #ifdef ALL_STATE
1022 	if (sp == NULL) {
1023 		gmtsub(timep, offset, tmp);
1024 		return;
1025 	}
1026 #endif /* defined ALL_STATE */
1027 	if (sp->timecnt == 0 || t < sp->ats[0]) {
1028 		i = 0;
1029 		while (sp->ttis[i].tt_isdst)
1030 			if (++i >= sp->typecnt) {
1031 				i = 0;
1032 				break;
1033 			}
1034 	} else {
1035 		for (i = 1; i < sp->timecnt; ++i)
1036 			if (t < sp->ats[i])
1037 				break;
1038 		i = sp->types[i - 1];
1039 	}
1040 	ttisp = &sp->ttis[i];
1041 	/*
1042 	** To get (wrong) behavior that's compatible with System V Release 2.0
1043 	** you'd replace the statement below with
1044 	**	t += ttisp->tt_gmtoff;
1045 	**	timesub(&t, 0L, sp, tmp);
1046 	*/
1047 	timesub(&t, ttisp->tt_gmtoff, sp, tmp);
1048 	tmp->tm_isdst = ttisp->tt_isdst;
1049 	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
1050 #ifdef TM_ZONE
1051 	tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
1052 #endif /* defined TM_ZONE */
1053 }
1054 
1055 struct tm *
1056 localtime(timep)
1057 const time_t * const	timep;
1058 {
1059 	tzset();
1060 	localsub(timep, 0L, &tm);
1061 	return &tm;
1062 }
1063 
1064 /*
1065 ** gmtsub is to gmtime as localsub is to localtime.
1066 */
1067 
1068 static void
1069 gmtsub(timep, offset, tmp)
1070 const time_t * const	timep;
1071 const long		offset;
1072 struct tm * const	tmp;
1073 {
1074 	if (!gmt_is_set) {
1075 		gmt_is_set = TRUE;
1076 #ifdef ALL_STATE
1077 		gmtptr = (struct state *) malloc(sizeof *gmtptr);
1078 		if (gmtptr != NULL)
1079 #endif /* defined ALL_STATE */
1080 			gmtload(gmtptr);
1081 	}
1082 	timesub(timep, offset, gmtptr, tmp);
1083 #ifdef TM_ZONE
1084 	/*
1085 	** Could get fancy here and deliver something such as
1086 	** "GMT+xxxx" or "GMT-xxxx" if offset is non-zero,
1087 	** but this is no time for a treasure hunt.
1088 	*/
1089 	if (offset != 0)
1090 		tmp->TM_ZONE = wildabbr;
1091 	else {
1092 #ifdef ALL_STATE
1093 		if (gmtptr == NULL)
1094 			tmp->TM_ZONE = gmt;
1095 		else	tmp->TM_ZONE = gmtptr->chars;
1096 #endif /* defined ALL_STATE */
1097 #ifndef ALL_STATE
1098 		tmp->TM_ZONE = gmtptr->chars;
1099 #endif /* State Farm */
1100 	}
1101 #endif /* defined TM_ZONE */
1102 }
1103 
1104 struct tm *
1105 gmtime(timep)
1106 const time_t * const	timep;
1107 {
1108 	gmtsub(timep, 0L, &tm);
1109 	return &tm;
1110 }
1111 
1112 #ifdef STD_INSPIRED
1113 
1114 struct tm *
1115 offtime(timep, offset)
1116 const time_t * const	timep;
1117 const long		offset;
1118 {
1119 	gmtsub(timep, offset, &tm);
1120 	return &tm;
1121 }
1122 
1123 #endif /* defined STD_INSPIRED */
1124 
1125 static void
1126 timesub(timep, offset, sp, tmp)
1127 const time_t * const			timep;
1128 const long				offset;
1129 register const struct state * const	sp;
1130 register struct tm * const		tmp;
1131 {
1132 	register const struct lsinfo *	lp;
1133 	register long			days;
1134 	register long			rem;
1135 	register int			y;
1136 	register int			yleap;
1137 	register const int *		ip;
1138 	register long			corr;
1139 	register int			hit;
1140 	register int			i;
1141 
1142 	corr = 0;
1143 	hit = 0;
1144 #ifdef ALL_STATE
1145 	i = (sp == NULL) ? 0 : sp->leapcnt;
1146 #endif /* defined ALL_STATE */
1147 #ifndef ALL_STATE
1148 	i = sp->leapcnt;
1149 #endif /* State Farm */
1150 	while (--i >= 0) {
1151 		lp = &sp->lsis[i];
1152 		if (*timep >= lp->ls_trans) {
1153 			if (*timep == lp->ls_trans) {
1154 				hit = ((i == 0 && lp->ls_corr > 0) ||
1155 					lp->ls_corr > sp->lsis[i - 1].ls_corr);
1156 				if (hit)
1157 					while (i > 0 &&
1158 						sp->lsis[i].ls_trans ==
1159 						sp->lsis[i - 1].ls_trans + 1 &&
1160 						sp->lsis[i].ls_corr ==
1161 						sp->lsis[i - 1].ls_corr + 1) {
1162 							++hit;
1163 							--i;
1164 					}
1165 			}
1166 			corr = lp->ls_corr;
1167 			break;
1168 		}
1169 	}
1170 	days = *timep / SECSPERDAY;
1171 	rem = *timep % SECSPERDAY;
1172 #ifdef mc68k
1173 	if (*timep == 0x80000000) {
1174 		/*
1175 		** A 3B1 muffs the division on the most negative number.
1176 		*/
1177 		days = -24855;
1178 		rem = -11648;
1179 	}
1180 #endif /* defined mc68k */
1181 	rem += (offset - corr);
1182 	while (rem < 0) {
1183 		rem += SECSPERDAY;
1184 		--days;
1185 	}
1186 	while (rem >= SECSPERDAY) {
1187 		rem -= SECSPERDAY;
1188 		++days;
1189 	}
1190 	tmp->tm_hour = (int) (rem / SECSPERHOUR);
1191 	rem = rem % SECSPERHOUR;
1192 	tmp->tm_min = (int) (rem / SECSPERMIN);
1193 	/*
1194 	** A positive leap second requires a special
1195 	** representation.  This uses "... ??:59:60" et seq.
1196 	*/
1197 	tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
1198 	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
1199 	if (tmp->tm_wday < 0)
1200 		tmp->tm_wday += DAYSPERWEEK;
1201 	y = EPOCH_YEAR;
1202 #define LEAPS_THRU_END_OF(y)	((y) / 4 - (y) / 100 + (y) / 400)
1203 	while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
1204 		register int	newy;
1205 
1206 		newy = y + days / DAYSPERNYEAR;
1207 		if (days < 0)
1208 			--newy;
1209 		days -= (newy - y) * DAYSPERNYEAR +
1210 			LEAPS_THRU_END_OF(newy - 1) -
1211 			LEAPS_THRU_END_OF(y - 1);
1212 		y = newy;
1213 	}
1214 	tmp->tm_year = y - TM_YEAR_BASE;
1215 	tmp->tm_yday = (int) days;
1216 	ip = mon_lengths[yleap];
1217 	for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
1218 		days = days - (long) ip[tmp->tm_mon];
1219 	tmp->tm_mday = (int) (days + 1);
1220 	tmp->tm_isdst = 0;
1221 #ifdef TM_GMTOFF
1222 	tmp->TM_GMTOFF = offset;
1223 #endif /* defined TM_GMTOFF */
1224 }
1225 
1226 char *
1227 ctime(timep)
1228 const time_t * const	timep;
1229 {
1230 /*
1231 ** Section 4.12.3.2 of X3.159-1989 requires that
1232 **	The ctime funciton converts the calendar time pointed to by timer
1233 **	to local time in the form of a string.  It is equivalent to
1234 **		asctime(localtime(timer))
1235 */
1236 	return asctime(localtime(timep));
1237 }
1238 
1239 /*
1240 ** Adapted from code provided by Robert Elz, who writes:
1241 **	The "best" way to do mktime I think is based on an idea of Bob
1242 **	Kridle's (so its said...) from a long time ago.
1243 **	[kridle@xinet.com as of 1996-01-16.]
1244 **	It does a binary search of the time_t space.  Since time_t's are
1245 **	just 32 bits, its a max of 32 iterations (even at 64 bits it
1246 **	would still be very reasonable).
1247 */
1248 
1249 #ifndef WRONG
1250 #define WRONG	(-1)
1251 #endif /* !defined WRONG */
1252 
1253 /*
1254 ** Simplified normalize logic courtesy Paul Eggert (eggert@twinsun.com).
1255 */
1256 
1257 static int
1258 increment_overflow(number, delta)
1259 int *	number;
1260 int	delta;
1261 {
1262 	int	number0;
1263 
1264 	number0 = *number;
1265 	*number += delta;
1266 	return (*number < number0) != (delta < 0);
1267 }
1268 
1269 static int
1270 normalize_overflow(tensptr, unitsptr, base)
1271 int * const	tensptr;
1272 int * const	unitsptr;
1273 const int	base;
1274 {
1275 	register int	tensdelta;
1276 
1277 	tensdelta = (*unitsptr >= 0) ?
1278 		(*unitsptr / base) :
1279 		(-1 - (-1 - *unitsptr) / base);
1280 	*unitsptr -= tensdelta * base;
1281 	return increment_overflow(tensptr, tensdelta);
1282 }
1283 
1284 static int
1285 tmcomp(atmp, btmp)
1286 register const struct tm * const atmp;
1287 register const struct tm * const btmp;
1288 {
1289 	register int	result;
1290 
1291 	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
1292 		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
1293 		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
1294 		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
1295 		(result = (atmp->tm_min - btmp->tm_min)) == 0)
1296 			result = atmp->tm_sec - btmp->tm_sec;
1297 	return result;
1298 }
1299 
1300 static time_t
1301 time2(tmp, funcp, offset, okayp)
1302 struct tm * const	tmp;
1303 void (* const		funcp) P((const time_t*, long, struct tm*));
1304 const long		offset;
1305 int * const		okayp;
1306 {
1307 	register const struct state *	sp;
1308 	register int			dir;
1309 	register int			bits;
1310 	register int			i, j ;
1311 	register int			saved_seconds;
1312 	time_t				newt;
1313 	time_t				t;
1314 	struct tm			yourtm, mytm;
1315 
1316 	*okayp = FALSE;
1317 	yourtm = *tmp;
1318 	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
1319 		return WRONG;
1320 	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
1321 		return WRONG;
1322 	if (normalize_overflow(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR))
1323 		return WRONG;
1324 	/*
1325 	** Turn yourtm.tm_year into an actual year number for now.
1326 	** It is converted back to an offset from TM_YEAR_BASE later.
1327 	*/
1328 	if (increment_overflow(&yourtm.tm_year, TM_YEAR_BASE))
1329 		return WRONG;
1330 	while (yourtm.tm_mday <= 0) {
1331 		if (increment_overflow(&yourtm.tm_year, -1))
1332 			return WRONG;
1333 		i = yourtm.tm_year + (1 < yourtm.tm_mon);
1334 		yourtm.tm_mday += year_lengths[isleap(i)];
1335 	}
1336 	while (yourtm.tm_mday > DAYSPERLYEAR) {
1337 		i = yourtm.tm_year + (1 < yourtm.tm_mon);
1338 		yourtm.tm_mday -= year_lengths[isleap(i)];
1339 		if (increment_overflow(&yourtm.tm_year, 1))
1340 			return WRONG;
1341 	}
1342 	for ( ; ; ) {
1343 		i = mon_lengths[isleap(yourtm.tm_year)][yourtm.tm_mon];
1344 		if (yourtm.tm_mday <= i)
1345 			break;
1346 		yourtm.tm_mday -= i;
1347 		if (++yourtm.tm_mon >= MONSPERYEAR) {
1348 			yourtm.tm_mon = 0;
1349 			if (increment_overflow(&yourtm.tm_year, 1))
1350 				return WRONG;
1351 		}
1352 	}
1353 	if (increment_overflow(&yourtm.tm_year, -TM_YEAR_BASE))
1354 		return WRONG;
1355 	if (yourtm.tm_year + TM_YEAR_BASE < EPOCH_YEAR) {
1356 		/*
1357 		** We can't set tm_sec to 0, because that might push the
1358 		** time below the minimum representable time.
1359 		** Set tm_sec to 59 instead.
1360 		** This assumes that the minimum representable time is
1361 		** not in the same minute that a leap second was deleted from,
1362 		** which is a safer assumption than using 58 would be.
1363 		*/
1364 		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
1365 			return WRONG;
1366 		saved_seconds = yourtm.tm_sec;
1367 		yourtm.tm_sec = SECSPERMIN - 1;
1368 	} else {
1369 		saved_seconds = yourtm.tm_sec;
1370 		yourtm.tm_sec = 0;
1371 	}
1372 	/*
1373 	** Divide the search space in half
1374 	** (this works whether time_t is signed or unsigned).
1375 	*/
1376 	bits = TYPE_BIT(time_t) - 1;
1377 	/*
1378 	** If time_t is signed, then 0 is just above the median,
1379 	** assuming two's complement arithmetic.
1380 	** If time_t is unsigned, then (1 << bits) is just above the median.
1381 	*/
1382 	t = TYPE_SIGNED(time_t) ? 0 : (((time_t) 1) << bits);
1383 	for ( ; ; ) {
1384 		(*funcp)(&t, offset, &mytm);
1385 		dir = tmcomp(&mytm, &yourtm);
1386 		if (dir != 0) {
1387 			if (bits-- < 0)
1388 				return WRONG;
1389 			if (bits < 0)
1390 				--t; /* may be needed if new t is minimal */
1391 			else if (dir > 0)
1392 				t -= ((time_t) 1) << bits;
1393 			else	t += ((time_t) 1) << bits;
1394 			continue;
1395 		}
1396 		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
1397 			break;
1398 		/*
1399 		** Right time, wrong type.
1400 		** Hunt for right time, right type.
1401 		** It's okay to guess wrong since the guess
1402 		** gets checked.
1403 		*/
1404 		/*
1405 		** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
1406 		*/
1407 		sp = (const struct state *)
1408 			(((void *) funcp == (void *) localsub) ?
1409 			lclptr : gmtptr);
1410 #ifdef ALL_STATE
1411 		if (sp == NULL)
1412 			return WRONG;
1413 #endif /* defined ALL_STATE */
1414 		for (i = sp->typecnt - 1; i >= 0; --i) {
1415 			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
1416 				continue;
1417 			for (j = sp->typecnt - 1; j >= 0; --j) {
1418 				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
1419 					continue;
1420 				newt = t + sp->ttis[j].tt_gmtoff -
1421 					sp->ttis[i].tt_gmtoff;
1422 				(*funcp)(&newt, offset, &mytm);
1423 				if (tmcomp(&mytm, &yourtm) != 0)
1424 					continue;
1425 				if (mytm.tm_isdst != yourtm.tm_isdst)
1426 					continue;
1427 				/*
1428 				** We have a match.
1429 				*/
1430 				t = newt;
1431 				goto label;
1432 			}
1433 		}
1434 		return WRONG;
1435 	}
1436 label:
1437 	newt = t + saved_seconds;
1438 	if ((newt < t) != (saved_seconds < 0))
1439 		return WRONG;
1440 	t = newt;
1441 	(*funcp)(&t, offset, tmp);
1442 	*okayp = TRUE;
1443 	return t;
1444 }
1445 
1446 static time_t
1447 time1(tmp, funcp, offset)
1448 struct tm * const	tmp;
1449 void (* const		funcp) P((const time_t *, long, struct tm *));
1450 const long		offset;
1451 {
1452 	register time_t			t;
1453 	register const struct state *	sp;
1454 	register int			samei, otheri;
1455 	int				okay;
1456 
1457 	if (tmp->tm_isdst > 1)
1458 		tmp->tm_isdst = 1;
1459 	t = time2(tmp, funcp, offset, &okay);
1460 #ifdef PCTS
1461 	/*
1462 	** PCTS code courtesy Grant Sullivan (grant@osf.org).
1463 	*/
1464 	if (okay)
1465 		return t;
1466 	if (tmp->tm_isdst < 0)
1467 		tmp->tm_isdst = 0;	/* reset to std and try again */
1468 #endif /* defined PCTS */
1469 #ifndef PCTS
1470 	if (okay || tmp->tm_isdst < 0)
1471 		return t;
1472 #endif /* !defined PCTS */
1473 	/*
1474 	** We're supposed to assume that somebody took a time of one type
1475 	** and did some math on it that yielded a "struct tm" that's bad.
1476 	** We try to divine the type they started from and adjust to the
1477 	** type they need.
1478 	*/
1479 	/*
1480 	** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
1481 	*/
1482 	sp = (const struct state *) (((void *) funcp == (void *) localsub) ?
1483 		lclptr : gmtptr);
1484 #ifdef ALL_STATE
1485 	if (sp == NULL)
1486 		return WRONG;
1487 #endif /* defined ALL_STATE */
1488 	for (samei = sp->typecnt - 1; samei >= 0; --samei) {
1489 		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
1490 			continue;
1491 		for (otheri = sp->typecnt - 1; otheri >= 0; --otheri) {
1492 			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
1493 				continue;
1494 			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
1495 					sp->ttis[samei].tt_gmtoff;
1496 			tmp->tm_isdst = !tmp->tm_isdst;
1497 			t = time2(tmp, funcp, offset, &okay);
1498 			if (okay)
1499 				return t;
1500 			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
1501 					sp->ttis[samei].tt_gmtoff;
1502 			tmp->tm_isdst = !tmp->tm_isdst;
1503 		}
1504 	}
1505 	return WRONG;
1506 }
1507 
1508 time_t
1509 mktime(tmp)
1510 struct tm * const	tmp;
1511 {
1512 	tzset();
1513 	return time1(tmp, localsub, 0L);
1514 }
1515 
1516 #ifdef STD_INSPIRED
1517 
1518 time_t
1519 timelocal(tmp)
1520 struct tm * const	tmp;
1521 {
1522 	tmp->tm_isdst = -1;	/* in case it wasn't initialized */
1523 	return mktime(tmp);
1524 }
1525 
1526 time_t
1527 timegm(tmp)
1528 struct tm * const	tmp;
1529 {
1530 	tmp->tm_isdst = 0;
1531 	return time1(tmp, gmtsub, 0L);
1532 }
1533 
1534 time_t
1535 timeoff(tmp, offset)
1536 struct tm * const	tmp;
1537 const long		offset;
1538 {
1539 	tmp->tm_isdst = 0;
1540 	return time1(tmp, gmtsub, offset);
1541 }
1542 
1543 #endif /* defined STD_INSPIRED */
1544 
1545 #ifdef CMUCS
1546 
1547 /*
1548 ** The following is supplied for compatibility with
1549 ** previous versions of the CMUCS runtime library.
1550 */
1551 
1552 long
1553 gtime(tmp)
1554 struct tm * const	tmp;
1555 {
1556 	const time_t	t = mktime(tmp);
1557 
1558 	if (t == WRONG)
1559 		return -1;
1560 	return t;
1561 }
1562 
1563 #endif /* defined CMUCS */
1564 
1565 /*
1566 ** XXX--is the below the right way to conditionalize??
1567 */
1568 
1569 #ifdef STD_INSPIRED
1570 
1571 /*
1572 ** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
1573 ** shall correspond to "Wed Dec 31 23:59:59 GMT 1986", which
1574 ** is not the case if we are accounting for leap seconds.
1575 ** So, we provide the following conversion routines for use
1576 ** when exchanging timestamps with POSIX conforming systems.
1577 */
1578 
1579 static long
1580 leapcorr(timep)
1581 time_t *	timep;
1582 {
1583 	register struct state *		sp;
1584 	register struct lsinfo *	lp;
1585 	register int			i;
1586 
1587 	sp = lclptr;
1588 	i = sp->leapcnt;
1589 	while (--i >= 0) {
1590 		lp = &sp->lsis[i];
1591 		if (*timep >= lp->ls_trans)
1592 			return lp->ls_corr;
1593 	}
1594 	return 0;
1595 }
1596 
1597 time_t
1598 time2posix(t)
1599 time_t	t;
1600 {
1601 	tzset();
1602 	return t - leapcorr(&t);
1603 }
1604 
1605 time_t
1606 posix2time(t)
1607 time_t	t;
1608 {
1609 	time_t	x;
1610 	time_t	y;
1611 
1612 	tzset();
1613 	/*
1614 	** For a positive leap second hit, the result
1615 	** is not unique.  For a negative leap second
1616 	** hit, the corresponding time doesn't exist,
1617 	** so we return an adjacent second.
1618 	*/
1619 	x = t + leapcorr(&t);
1620 	y = x - leapcorr(&x);
1621 	if (y < t) {
1622 		do {
1623 			x++;
1624 			y = x - leapcorr(&x);
1625 		} while (y < t);
1626 		if (t != y)
1627 			return x - 1;
1628 	} else if (y > t) {
1629 		do {
1630 			--x;
1631 			y = x - leapcorr(&x);
1632 		} while (y > t);
1633 		if (t != y)
1634 			return x + 1;
1635 	}
1636 	return x;
1637 }
1638 
1639 #endif /* defined STD_INSPIRED */
1640