xref: /netbsd-src/lib/libc/time/localtime.c (revision a4ddc2c8fb9af816efe3b1c375a5530aef0e89e9)
1 /*	$NetBSD: localtime.c,v 1.73 2013/03/02 21:24:28 christos Exp $	*/
2 
3 /*
4 ** This file is in the public domain, so clarified as of
5 ** 1996-06-05 by Arthur David Olson.
6 */
7 
8 #include <sys/cdefs.h>
9 #if defined(LIBC_SCCS) && !defined(lint)
10 #if 0
11 static char	elsieid[] = "@(#)localtime.c	8.17";
12 #else
13 __RCSID("$NetBSD: localtime.c,v 1.73 2013/03/02 21:24:28 christos Exp $");
14 #endif
15 #endif /* LIBC_SCCS and not lint */
16 
17 /*
18 ** Leap second handling from Bradley White.
19 ** POSIX-style TZ environment variable handling from Guy Harris.
20 */
21 
22 /*LINTLIBRARY*/
23 
24 #include "namespace.h"
25 #include "private.h"
26 #include "tzfile.h"
27 #include "fcntl.h"
28 #include "reentrant.h"
29 
30 #if defined(__weak_alias)
31 __weak_alias(daylight,_daylight)
32 __weak_alias(tzname,_tzname)
33 #endif
34 
35 #include "float.h"	/* for FLT_MAX and DBL_MAX */
36 
37 #ifndef TZ_ABBR_MAX_LEN
38 #define TZ_ABBR_MAX_LEN	16
39 #endif /* !defined TZ_ABBR_MAX_LEN */
40 
41 #ifndef TZ_ABBR_CHAR_SET
42 #define TZ_ABBR_CHAR_SET \
43 	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
44 #endif /* !defined TZ_ABBR_CHAR_SET */
45 
46 #ifndef TZ_ABBR_ERR_CHAR
47 #define TZ_ABBR_ERR_CHAR	'_'
48 #endif /* !defined TZ_ABBR_ERR_CHAR */
49 
50 /*
51 ** SunOS 4.1.1 headers lack O_BINARY.
52 */
53 
54 #ifdef O_BINARY
55 #define OPEN_MODE	(O_RDONLY | O_BINARY)
56 #endif /* defined O_BINARY */
57 #ifndef O_BINARY
58 #define OPEN_MODE	O_RDONLY
59 #endif /* !defined O_BINARY */
60 
61 #ifndef WILDABBR
62 /*
63 ** Someone might make incorrect use of a time zone abbreviation:
64 **	1.	They might reference tzname[0] before calling tzset (explicitly
65 **		or implicitly).
66 **	2.	They might reference tzname[1] before calling tzset (explicitly
67 **		or implicitly).
68 **	3.	They might reference tzname[1] after setting to a time zone
69 **		in which Daylight Saving Time is never observed.
70 **	4.	They might reference tzname[0] after setting to a time zone
71 **		in which Standard Time is never observed.
72 **	5.	They might reference tm.TM_ZONE after calling offtime.
73 ** What's best to do in the above cases is open to debate;
74 ** for now, we just set things up so that in any of the five cases
75 ** WILDABBR is used. Another possibility: initialize tzname[0] to the
76 ** string "tzname[0] used before set", and similarly for the other cases.
77 ** And another: initialize tzname[0] to "ERA", with an explanation in the
78 ** manual page of what this "time zone abbreviation" means (doing this so
79 ** that tzname[0] has the "normal" length of three characters).
80 */
81 #define WILDABBR	"   "
82 #endif /* !defined WILDABBR */
83 
84 static const char	wildabbr[] = WILDABBR;
85 
86 static const char	gmt[] = "GMT";
87 
88 /*
89 ** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
90 ** We default to US rules as of 1999-08-17.
91 ** POSIX 1003.1 section 8.1.1 says that the default DST rules are
92 ** implementation dependent; for historical reasons, US rules are a
93 ** common default.
94 */
95 #ifndef TZDEFRULESTRING
96 #define TZDEFRULESTRING ",M4.1.0,M10.5.0"
97 #endif /* !defined TZDEFDST */
98 
99 struct ttinfo {				/* time type information */
100 	long		tt_gmtoff;	/* UTC offset in seconds */
101 	int		tt_isdst;	/* used to set tm_isdst */
102 	int		tt_abbrind;	/* abbreviation list index */
103 	int		tt_ttisstd;	/* TRUE if transition is std time */
104 	int		tt_ttisgmt;	/* TRUE if transition is UTC */
105 };
106 
107 struct lsinfo {				/* leap second information */
108 	time_t		ls_trans;	/* transition time */
109 	long		ls_corr;	/* correction to apply */
110 };
111 
112 #define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))
113 
114 #ifdef TZNAME_MAX
115 #define MY_TZNAME_MAX	TZNAME_MAX
116 #endif /* defined TZNAME_MAX */
117 #ifndef TZNAME_MAX
118 #define MY_TZNAME_MAX	255
119 #endif /* !defined TZNAME_MAX */
120 
121 struct __state {
122 	int		leapcnt;
123 	int		timecnt;
124 	int		typecnt;
125 	int		charcnt;
126 	int		goback;
127 	int		goahead;
128 	time_t		ats[TZ_MAX_TIMES];
129 	unsigned char	types[TZ_MAX_TIMES];
130 	struct ttinfo	ttis[TZ_MAX_TYPES];
131 	char		chars[/*CONSTCOND*/BIGGEST(BIGGEST(TZ_MAX_CHARS + 1,
132 				sizeof gmt), (2 * (MY_TZNAME_MAX + 1)))];
133 	struct lsinfo	lsis[TZ_MAX_LEAPS];
134 };
135 
136 struct rule {
137 	int		r_type;		/* type of rule--see below */
138 	int		r_day;		/* day number of rule */
139 	int		r_week;		/* week number of rule */
140 	int		r_mon;		/* month number of rule */
141 	long		r_time;		/* transition time of rule */
142 };
143 
144 #define JULIAN_DAY		0	/* Jn - Julian day */
145 #define DAY_OF_YEAR		1	/* n - day of year */
146 #define MONTH_NTH_DAY_OF_WEEK	2	/* Mm.n.d - month, week, day of week */
147 
148 typedef struct tm *(*subfun_t)(const timezone_t sp, const time_t *timep,
149 			       long offset, struct tm *tmp);
150 
151 /*
152 ** Prototypes for static functions.
153 */
154 
155 static long		detzcode(const char * codep);
156 static time_t		detzcode64(const char * codep);
157 static int		differ_by_repeat(time_t t1, time_t t0);
158 static const char *	getzname(const char * strp) __pure;
159 static const char *	getqzname(const char * strp, const int delim) __pure;
160 static const char *	getnum(const char * strp, int * nump, int min,
161 				int max);
162 static const char *	getsecs(const char * strp, long * secsp);
163 static const char *	getoffset(const char * strp, long * offsetp);
164 static const char *	getrule(const char * strp, struct rule * rulep);
165 static void		gmtload(timezone_t sp);
166 static struct tm *	gmtsub(const timezone_t sp, const time_t *timep,
167 				long offset, struct tm * tmp);
168 static struct tm *	localsub(const timezone_t sp, const time_t *timep,
169 				long offset, struct tm *tmp);
170 static int		increment_overflow(int * number, int delta);
171 static int		leaps_thru_end_of(int y) __pure;
172 static int		long_increment_overflow(long * number, int delta);
173 static int		long_normalize_overflow(long * tensptr,
174 				int * unitsptr, int base);
175 static int		normalize_overflow(int * tensptr, int * unitsptr,
176 				int base);
177 static void		settzname(void);
178 static time_t		time1(const timezone_t sp, struct tm * const tmp,
179 				subfun_t funcp, const long offset);
180 static time_t		time2(const timezone_t sp, struct tm * const tmp,
181 				subfun_t funcp,
182 				const long offset, int *const okayp);
183 static time_t		time2sub(const timezone_t sp, struct tm * const tmp,
184 				subfun_t funcp, const long offset,
185 				int *const okayp, const int do_norm_secs);
186 static struct tm *	timesub(const timezone_t sp, const time_t * timep,
187 				long offset, struct tm * tmp);
188 static int		tmcomp(const struct tm * atmp,
189 				const struct tm * btmp);
190 static time_t		transtime(time_t janfirst, int year,
191 				const struct rule * rulep, long offset) __pure;
192 static int		typesequiv(const timezone_t sp, int a, int b);
193 static int		tzload(timezone_t sp, const char * name,
194 				int doextend);
195 static int		tzparse(timezone_t sp, const char * name,
196 				int lastditch);
197 static void		tzset_unlocked(void);
198 static void		tzsetwall_unlocked(void);
199 static long		leapcorr(const timezone_t sp, time_t * timep);
200 
201 static timezone_t lclptr;
202 static timezone_t gmtptr;
203 
204 #ifndef TZ_STRLEN_MAX
205 #define TZ_STRLEN_MAX 255
206 #endif /* !defined TZ_STRLEN_MAX */
207 
208 static char		lcl_TZname[TZ_STRLEN_MAX + 1];
209 static int		lcl_is_set;
210 static int		gmt_is_set;
211 
212 #if !defined(__LIBC12_SOURCE__)
213 
214 __aconst char *		tzname[2] = {
215 	(__aconst char *)__UNCONST(wildabbr),
216 	(__aconst char *)__UNCONST(wildabbr)
217 };
218 
219 #else
220 
221 extern __aconst char *	tzname[2];
222 
223 #endif
224 
225 #ifdef _REENTRANT
226 static rwlock_t lcl_lock = RWLOCK_INITIALIZER;
227 #endif
228 
229 /*
230 ** Section 4.12.3 of X3.159-1989 requires that
231 **	Except for the strftime function, these functions [asctime,
232 **	ctime, gmtime, localtime] return values in one of two static
233 **	objects: a broken-down time structure and an array of char.
234 ** Thanks to Paul Eggert for noting this.
235 */
236 
237 static struct tm	tm;
238 
239 #ifdef USG_COMPAT
240 #if !defined(__LIBC12_SOURCE__)
241 long 			timezone = 0;
242 int			daylight = 0;
243 #else
244 extern int		daylight;
245 extern long		timezone __RENAME(__timezone13);
246 #endif
247 #endif /* defined USG_COMPAT */
248 
249 #ifdef ALTZONE
250 time_t			altzone = 0;
251 #endif /* defined ALTZONE */
252 
253 static long
254 detzcode(const char *const codep)
255 {
256 	long	result;
257 	int	i;
258 
259 	result = (codep[0] & 0x80) ? ~0L : 0;
260 	for (i = 0; i < 4; ++i)
261 		result = (result << 8) | (codep[i] & 0xff);
262 	return result;
263 }
264 
265 static time_t
266 detzcode64(const char *const codep)
267 {
268 	time_t	result;
269 	int	i;
270 
271 	result = (time_t)((codep[0] & 0x80) ? (~(int_fast64_t) 0) : 0);
272 	for (i = 0; i < 8; ++i)
273 		result = result * 256 + (codep[i] & 0xff);
274 	return result;
275 }
276 
277 const char *
278 tzgetname(const timezone_t sp, int isdst)
279 {
280 	int i;
281 	for (i = 0; i < sp->timecnt; ++i) {
282 		const struct ttinfo *const ttisp = &sp->ttis[sp->types[i]];
283 
284 		if (ttisp->tt_isdst == isdst)
285 			return &sp->chars[ttisp->tt_abbrind];
286 	}
287 	return NULL;
288 }
289 
290 static void
291 settzname_z(timezone_t sp)
292 {
293 	int			i;
294 
295 	/*
296 	** Scrub the abbreviations.
297 	** First, replace bogus characters.
298 	*/
299 	for (i = 0; i < sp->charcnt; ++i)
300 		if (strchr(TZ_ABBR_CHAR_SET, sp->chars[i]) == NULL)
301 			sp->chars[i] = TZ_ABBR_ERR_CHAR;
302 	/*
303 	** Second, truncate long abbreviations.
304 	*/
305 	for (i = 0; i < sp->typecnt; ++i) {
306 		const struct ttinfo * const	ttisp = &sp->ttis[i];
307 		char *				cp = &sp->chars[ttisp->tt_abbrind];
308 
309 		if (strlen(cp) > TZ_ABBR_MAX_LEN &&
310 			strcmp(cp, GRANDPARENTED) != 0)
311 				*(cp + TZ_ABBR_MAX_LEN) = '\0';
312 	}
313 }
314 
315 static void
316 settzname(void)
317 {
318 	timezone_t const	sp = lclptr;
319 	int			i;
320 
321 	tzname[0] = (__aconst char *)__UNCONST(wildabbr);
322 	tzname[1] = (__aconst char *)__UNCONST(wildabbr);
323 #ifdef USG_COMPAT
324 	daylight = 0;
325 	timezone = 0;
326 #endif /* defined USG_COMPAT */
327 #ifdef ALTZONE
328 	altzone = 0;
329 #endif /* defined ALTZONE */
330 	if (sp == NULL) {
331 		tzname[0] = tzname[1] = (__aconst char *)__UNCONST(gmt);
332 		return;
333 	}
334 	/*
335 	** And to get the latest zone names into tzname. . .
336 	*/
337 	for (i = 0; i < sp->typecnt; ++i) {
338 		const struct ttinfo * const	ttisp = &sp->ttis[i];
339 
340 		tzname[ttisp->tt_isdst] = &sp->chars[ttisp->tt_abbrind];
341 #ifdef USG_COMPAT
342 		if (ttisp->tt_isdst)
343 			daylight = 1;
344 		if (!ttisp->tt_isdst)
345 			timezone = -(ttisp->tt_gmtoff);
346 #endif /* defined USG_COMPAT */
347 #ifdef ALTZONE
348 		if (ttisp->tt_isdst)
349 			altzone = -(ttisp->tt_gmtoff);
350 #endif /* defined ALTZONE */
351 	}
352 	settzname_z(sp);
353 }
354 
355 static int
356 differ_by_repeat(const time_t t1, const time_t t0)
357 {
358 	if (TYPE_INTEGRAL(time_t) &&
359 		TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
360 			return 0;
361 	return (int_fast64_t)t1 - (int_fast64_t)t0 == SECSPERREPEAT;
362 }
363 
364 static int
365 tzload(timezone_t sp, const char *name, const int doextend)
366 {
367 	const char *		p;
368 	int			i;
369 	int			fid;
370 	int			stored;
371 	ssize_t			nread;
372 	typedef union {
373 		struct tzhead	tzhead;
374 		char		buf[2 * sizeof(struct tzhead) +
375 					2 * sizeof *sp +
376 					4 * TZ_MAX_TIMES];
377 	} u_t;
378 	u_t *			up;
379 
380 	up = calloc(1, sizeof *up);
381 	if (up == NULL)
382 		return -1;
383 
384 	sp->goback = sp->goahead = FALSE;
385 	if (name == NULL && (name = TZDEFAULT) == NULL)
386 		goto oops;
387 	{
388 		int	doaccess;
389 		/*
390 		** Section 4.9.1 of the C standard says that
391 		** "FILENAME_MAX expands to an integral constant expression
392 		** that is the size needed for an array of char large enough
393 		** to hold the longest file name string that the implementation
394 		** guarantees can be opened."
395 		*/
396 		char		fullname[FILENAME_MAX + 1];
397 
398 		if (name[0] == ':')
399 			++name;
400 		doaccess = name[0] == '/';
401 		if (!doaccess) {
402 			if ((p = TZDIR) == NULL)
403 				goto oops;
404 			if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
405 				goto oops;
406 			(void) strcpy(fullname, p);	/* XXX strcpy is safe */
407 			(void) strcat(fullname, "/");	/* XXX strcat is safe */
408 			(void) strcat(fullname, name);	/* XXX strcat is safe */
409 			/*
410 			** Set doaccess if '.' (as in "../") shows up in name.
411 			*/
412 			if (strchr(name, '.') != NULL)
413 				doaccess = TRUE;
414 			name = fullname;
415 		}
416 		if (doaccess && access(name, R_OK) != 0)
417 			goto oops;
418 		/*
419 		 * XXX potential security problem here if user of a set-id
420 		 * program has set TZ (which is passed in as name) here,
421 		 * and uses a race condition trick to defeat the access(2)
422 		 * above.
423 		 */
424 		if ((fid = open(name, OPEN_MODE)) == -1)
425 			goto oops;
426 	}
427 	nread = read(fid, up->buf, sizeof up->buf);
428 	if (close(fid) < 0 || nread <= 0)
429 		goto oops;
430 	for (stored = 4; stored <= 8; stored *= 2) {
431 		int		ttisstdcnt;
432 		int		ttisgmtcnt;
433 
434 		ttisstdcnt = (int) detzcode(up->tzhead.tzh_ttisstdcnt);
435 		ttisgmtcnt = (int) detzcode(up->tzhead.tzh_ttisgmtcnt);
436 		sp->leapcnt = (int) detzcode(up->tzhead.tzh_leapcnt);
437 		sp->timecnt = (int) detzcode(up->tzhead.tzh_timecnt);
438 		sp->typecnt = (int) detzcode(up->tzhead.tzh_typecnt);
439 		sp->charcnt = (int) detzcode(up->tzhead.tzh_charcnt);
440 		p = up->tzhead.tzh_charcnt + sizeof up->tzhead.tzh_charcnt;
441 		if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
442 			sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
443 			sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
444 			sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
445 			(ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
446 			(ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
447 				goto oops;
448 		if (nread - (p - up->buf) <
449 			sp->timecnt * stored +		/* ats */
450 			sp->timecnt +			/* types */
451 			sp->typecnt * 6 +		/* ttinfos */
452 			sp->charcnt +			/* chars */
453 			sp->leapcnt * (stored + 4) +	/* lsinfos */
454 			ttisstdcnt +			/* ttisstds */
455 			ttisgmtcnt)			/* ttisgmts */
456 				goto oops;
457 		for (i = 0; i < sp->timecnt; ++i) {
458 			sp->ats[i] = (time_t)((stored == 4) ?
459 				detzcode(p) : detzcode64(p));
460 			p += stored;
461 		}
462 		for (i = 0; i < sp->timecnt; ++i) {
463 			sp->types[i] = (unsigned char) *p++;
464 			if (sp->types[i] >= sp->typecnt)
465 				goto oops;
466 		}
467 		for (i = 0; i < sp->typecnt; ++i) {
468 			struct ttinfo *	ttisp;
469 
470 			ttisp = &sp->ttis[i];
471 			ttisp->tt_gmtoff = detzcode(p);
472 			p += 4;
473 			ttisp->tt_isdst = (unsigned char) *p++;
474 			if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
475 				goto oops;
476 			ttisp->tt_abbrind = (unsigned char) *p++;
477 			if (ttisp->tt_abbrind < 0 ||
478 				ttisp->tt_abbrind > sp->charcnt)
479 					goto oops;
480 		}
481 		for (i = 0; i < sp->charcnt; ++i)
482 			sp->chars[i] = *p++;
483 		sp->chars[i] = '\0';	/* ensure '\0' at end */
484 		for (i = 0; i < sp->leapcnt; ++i) {
485 			struct lsinfo *	lsisp;
486 
487 			lsisp = &sp->lsis[i];
488 			lsisp->ls_trans = (time_t)((stored == 4) ?
489 			    detzcode(p) : detzcode64(p));
490 			p += stored;
491 			lsisp->ls_corr = detzcode(p);
492 			p += 4;
493 		}
494 		for (i = 0; i < sp->typecnt; ++i) {
495 			struct ttinfo *	ttisp;
496 
497 			ttisp = &sp->ttis[i];
498 			if (ttisstdcnt == 0)
499 				ttisp->tt_ttisstd = FALSE;
500 			else {
501 				ttisp->tt_ttisstd = *p++;
502 				if (ttisp->tt_ttisstd != TRUE &&
503 					ttisp->tt_ttisstd != FALSE)
504 						goto oops;
505 			}
506 		}
507 		for (i = 0; i < sp->typecnt; ++i) {
508 			struct ttinfo *	ttisp;
509 
510 			ttisp = &sp->ttis[i];
511 			if (ttisgmtcnt == 0)
512 				ttisp->tt_ttisgmt = FALSE;
513 			else {
514 				ttisp->tt_ttisgmt = *p++;
515 				if (ttisp->tt_ttisgmt != TRUE &&
516 					ttisp->tt_ttisgmt != FALSE)
517 						goto oops;
518 			}
519 		}
520 		/*
521 		** Out-of-sort ats should mean we're running on a
522 		** signed time_t system but using a data file with
523 		** unsigned values (or vice versa).
524 		*/
525 		for (i = 0; i < sp->timecnt; ++i)
526 			if ((i < sp->timecnt - 1 &&
527 			    sp->ats[i] > sp->ats[i + 1]) ||
528 			    (i == sp->timecnt - 1 && !TYPE_SIGNED(time_t) &&
529 			    sp->ats[i] >
530 			    ((stored == 4) ? INT32_MAX : INT64_MAX))) {
531 				if (TYPE_SIGNED(time_t)) {
532 					/*
533 					** Ignore the end (easy).
534 					*/
535 					sp->timecnt = i + 1;
536 				} else {
537 					/*
538 					** Ignore the beginning (harder).
539 					*/
540 					int	j;
541 
542 					/*
543 					** Keep the record right before the
544 					** epoch boundary,
545 					** but tweak it so that it starts
546 					** right with the epoch
547 					** (thanks to Doug Bailey).
548 					*/
549 					sp->ats[i] = 0;
550 					for (j = 0; j + i < sp->timecnt; ++j) {
551 						sp->ats[j] = sp->ats[j + i];
552 						sp->types[j] = sp->types[j + i];
553 					}
554 					sp->timecnt = j;
555 				}
556 				break;
557 			}
558 		/*
559 		** If this is an old file, we're done.
560 		*/
561 		if (up->tzhead.tzh_version[0] == '\0')
562 			break;
563 		nread -= p - up->buf;
564 		for (i = 0; i < nread; ++i)
565 			up->buf[i] = p[i];
566 		/*
567 		** If this is a narrow integer time_t system, we're done.
568 		*/
569 		if (stored >= (int) sizeof(time_t)
570 /* CONSTCOND */
571 				&& TYPE_INTEGRAL(time_t))
572 			break;
573 	}
574 	if (doextend && nread > 2 &&
575 		up->buf[0] == '\n' && up->buf[nread - 1] == '\n' &&
576 		sp->typecnt + 2 <= TZ_MAX_TYPES) {
577 			struct __state ts;
578 			int	result;
579 
580 			up->buf[nread - 1] = '\0';
581 			result = tzparse(&ts, &up->buf[1], FALSE);
582 			if (result == 0 && ts.typecnt == 2 &&
583 				sp->charcnt + ts.charcnt <= TZ_MAX_CHARS) {
584 					for (i = 0; i < 2; ++i)
585 						ts.ttis[i].tt_abbrind +=
586 							sp->charcnt;
587 					for (i = 0; i < ts.charcnt; ++i)
588 						sp->chars[sp->charcnt++] =
589 							ts.chars[i];
590 					i = 0;
591 					while (i < ts.timecnt &&
592 						ts.ats[i] <=
593 						sp->ats[sp->timecnt - 1])
594 							++i;
595 					while (i < ts.timecnt &&
596 					    sp->timecnt < TZ_MAX_TIMES) {
597 						sp->ats[sp->timecnt] =
598 							ts.ats[i];
599 						sp->types[sp->timecnt] =
600 							sp->typecnt +
601 							ts.types[i];
602 						++sp->timecnt;
603 						++i;
604 					}
605 					sp->ttis[sp->typecnt++] = ts.ttis[0];
606 					sp->ttis[sp->typecnt++] = ts.ttis[1];
607 			}
608 	}
609 	if (sp->timecnt > 1) {
610 		for (i = 1; i < sp->timecnt; ++i)
611 			if (typesequiv(sp, sp->types[i], sp->types[0]) &&
612 				differ_by_repeat(sp->ats[i], sp->ats[0])) {
613 					sp->goback = TRUE;
614 					break;
615 				}
616 		for (i = sp->timecnt - 2; i >= 0; --i)
617 			if (typesequiv(sp, sp->types[sp->timecnt - 1],
618 				sp->types[i]) &&
619 				differ_by_repeat(sp->ats[sp->timecnt - 1],
620 				sp->ats[i])) {
621 					sp->goahead = TRUE;
622 					break;
623 		}
624 	}
625 	free(up);
626 	return 0;
627 oops:
628 	free(up);
629 	return -1;
630 }
631 
632 static int
633 typesequiv(const timezone_t sp, const int a, const int b)
634 {
635 	int	result;
636 
637 	if (sp == NULL ||
638 		a < 0 || a >= sp->typecnt ||
639 		b < 0 || b >= sp->typecnt)
640 			result = FALSE;
641 	else {
642 		const struct ttinfo *	ap = &sp->ttis[a];
643 		const struct ttinfo *	bp = &sp->ttis[b];
644 		result = ap->tt_gmtoff == bp->tt_gmtoff &&
645 			ap->tt_isdst == bp->tt_isdst &&
646 			ap->tt_ttisstd == bp->tt_ttisstd &&
647 			ap->tt_ttisgmt == bp->tt_ttisgmt &&
648 			strcmp(&sp->chars[ap->tt_abbrind],
649 			&sp->chars[bp->tt_abbrind]) == 0;
650 	}
651 	return result;
652 }
653 
654 static const int	mon_lengths[2][MONSPERYEAR] = {
655 	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
656 	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
657 };
658 
659 static const int	year_lengths[2] = {
660 	DAYSPERNYEAR, DAYSPERLYEAR
661 };
662 
663 /*
664 ** Given a pointer into a time zone string, scan until a character that is not
665 ** a valid character in a zone name is found. Return a pointer to that
666 ** character.
667 */
668 
669 static const char *
670 getzname(const char *strp)
671 {
672 	char	c;
673 
674 	while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
675 		c != '+')
676 			++strp;
677 	return strp;
678 }
679 
680 /*
681 ** Given a pointer into an extended time zone string, scan until the ending
682 ** delimiter of the zone name is located. Return a pointer to the delimiter.
683 **
684 ** As with getzname above, the legal character set is actually quite
685 ** restricted, with other characters producing undefined results.
686 ** We don't do any checking here; checking is done later in common-case code.
687 */
688 
689 static const char *
690 getqzname(const char *strp, const int delim)
691 {
692 	int	c;
693 
694 	while ((c = *strp) != '\0' && c != delim)
695 		++strp;
696 	return strp;
697 }
698 
699 /*
700 ** Given a pointer into a time zone string, extract a number from that string.
701 ** Check that the number is within a specified range; if it is not, return
702 ** NULL.
703 ** Otherwise, return a pointer to the first character not part of the number.
704 */
705 
706 static const char *
707 getnum(const char *strp, int *const nump, const int min, const int max)
708 {
709 	char	c;
710 	int	num;
711 
712 	if (strp == NULL || !is_digit(c = *strp)) {
713 		errno = EINVAL;
714 		return NULL;
715 	}
716 	num = 0;
717 	do {
718 		num = num * 10 + (c - '0');
719 		if (num > max) {
720 			errno = EOVERFLOW;
721 			return NULL;	/* illegal value */
722 		}
723 		c = *++strp;
724 	} while (is_digit(c));
725 	if (num < min) {
726 		errno = EINVAL;
727 		return NULL;		/* illegal value */
728 	}
729 	*nump = num;
730 	return strp;
731 }
732 
733 /*
734 ** Given a pointer into a time zone string, extract a number of seconds,
735 ** in hh[:mm[:ss]] form, from the string.
736 ** If any error occurs, return NULL.
737 ** Otherwise, return a pointer to the first character not part of the number
738 ** of seconds.
739 */
740 
741 static const char *
742 getsecs(const char *strp, long *const secsp)
743 {
744 	int	num;
745 
746 	/*
747 	** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
748 	** "M10.4.6/26", which does not conform to Posix,
749 	** but which specifies the equivalent of
750 	** ``02:00 on the first Sunday on or after 23 Oct''.
751 	*/
752 	strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
753 	if (strp == NULL)
754 		return NULL;
755 	*secsp = num * (long) SECSPERHOUR;
756 	if (*strp == ':') {
757 		++strp;
758 		strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
759 		if (strp == NULL)
760 			return NULL;
761 		*secsp += num * SECSPERMIN;
762 		if (*strp == ':') {
763 			++strp;
764 			/* `SECSPERMIN' allows for leap seconds. */
765 			strp = getnum(strp, &num, 0, SECSPERMIN);
766 			if (strp == NULL)
767 				return NULL;
768 			*secsp += num;
769 		}
770 	}
771 	return strp;
772 }
773 
774 /*
775 ** Given a pointer into a time zone string, extract an offset, in
776 ** [+-]hh[:mm[:ss]] form, from the string.
777 ** If any error occurs, return NULL.
778 ** Otherwise, return a pointer to the first character not part of the time.
779 */
780 
781 static const char *
782 getoffset(const char *strp, long *const offsetp)
783 {
784 	int	neg = 0;
785 
786 	if (*strp == '-') {
787 		neg = 1;
788 		++strp;
789 	} else if (*strp == '+')
790 		++strp;
791 	strp = getsecs(strp, offsetp);
792 	if (strp == NULL)
793 		return NULL;		/* illegal time */
794 	if (neg)
795 		*offsetp = -*offsetp;
796 	return strp;
797 }
798 
799 /*
800 ** Given a pointer into a time zone string, extract a rule in the form
801 ** date[/time]. See POSIX section 8 for the format of "date" and "time".
802 ** If a valid rule is not found, return NULL.
803 ** Otherwise, return a pointer to the first character not part of the rule.
804 */
805 
806 static const char *
807 getrule(const char *strp, struct rule *const rulep)
808 {
809 	if (*strp == 'J') {
810 		/*
811 		** Julian day.
812 		*/
813 		rulep->r_type = JULIAN_DAY;
814 		++strp;
815 		strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
816 	} else if (*strp == 'M') {
817 		/*
818 		** Month, week, day.
819 		*/
820 		rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
821 		++strp;
822 		strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
823 		if (strp == NULL)
824 			return NULL;
825 		if (*strp++ != '.')
826 			return NULL;
827 		strp = getnum(strp, &rulep->r_week, 1, 5);
828 		if (strp == NULL)
829 			return NULL;
830 		if (*strp++ != '.')
831 			return NULL;
832 		strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
833 	} else if (is_digit(*strp)) {
834 		/*
835 		** Day of year.
836 		*/
837 		rulep->r_type = DAY_OF_YEAR;
838 		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
839 	} else	return NULL;		/* invalid format */
840 	if (strp == NULL)
841 		return NULL;
842 	if (*strp == '/') {
843 		/*
844 		** Time specified.
845 		*/
846 		++strp;
847 		strp = getsecs(strp, &rulep->r_time);
848 	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
849 	return strp;
850 }
851 
852 /*
853 ** Given the Epoch-relative time of January 1, 00:00:00 UTC, in a year, the
854 ** year, a rule, and the offset from UTC at the time that rule takes effect,
855 ** calculate the Epoch-relative time that rule takes effect.
856 */
857 
858 static time_t
859 transtime(const time_t janfirst, const int year, const struct rule *const rulep,
860     const long offset)
861 {
862 	int	leapyear;
863 	time_t	value;
864 	int	i;
865 	int		d, m1, yy0, yy1, yy2, dow;
866 
867 	INITIALIZE(value);
868 	leapyear = isleap(year);
869 	switch (rulep->r_type) {
870 
871 	case JULIAN_DAY:
872 		/*
873 		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
874 		** years.
875 		** In non-leap years, or if the day number is 59 or less, just
876 		** add SECSPERDAY times the day number-1 to the time of
877 		** January 1, midnight, to get the day.
878 		*/
879 		value = (time_t)(janfirst + (rulep->r_day - 1) * SECSPERDAY);
880 		if (leapyear && rulep->r_day >= 60)
881 			value += SECSPERDAY;
882 		break;
883 
884 	case DAY_OF_YEAR:
885 		/*
886 		** n - day of year.
887 		** Just add SECSPERDAY times the day number to the time of
888 		** January 1, midnight, to get the day.
889 		*/
890 		value = (time_t)(janfirst + rulep->r_day * SECSPERDAY);
891 		break;
892 
893 	case MONTH_NTH_DAY_OF_WEEK:
894 		/*
895 		** Mm.n.d - nth "dth day" of month m.
896 		*/
897 		value = janfirst;
898 		for (i = 0; i < rulep->r_mon - 1; ++i)
899 			value += (time_t)(mon_lengths[leapyear][i] * SECSPERDAY);
900 
901 		/*
902 		** Use Zeller's Congruence to get day-of-week of first day of
903 		** month.
904 		*/
905 		m1 = (rulep->r_mon + 9) % 12 + 1;
906 		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
907 		yy1 = yy0 / 100;
908 		yy2 = yy0 % 100;
909 		dow = ((26 * m1 - 2) / 10 +
910 			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
911 		if (dow < 0)
912 			dow += DAYSPERWEEK;
913 
914 		/*
915 		** "dow" is the day-of-week of the first day of the month. Get
916 		** the day-of-month (zero-origin) of the first "dow" day of the
917 		** month.
918 		*/
919 		d = rulep->r_day - dow;
920 		if (d < 0)
921 			d += DAYSPERWEEK;
922 		for (i = 1; i < rulep->r_week; ++i) {
923 			if (d + DAYSPERWEEK >=
924 				mon_lengths[leapyear][rulep->r_mon - 1])
925 					break;
926 			d += DAYSPERWEEK;
927 		}
928 
929 		/*
930 		** "d" is the day-of-month (zero-origin) of the day we want.
931 		*/
932 		value += (time_t)(d * SECSPERDAY);
933 		break;
934 	}
935 
936 	/*
937 	** "value" is the Epoch-relative time of 00:00:00 UTC on the day in
938 	** question. To get the Epoch-relative time of the specified local
939 	** time on that day, add the transition time and the current offset
940 	** from UTC.
941 	*/
942 	return (time_t)(value + rulep->r_time + offset);
943 }
944 
945 /*
946 ** Given a POSIX section 8-style TZ string, fill in the rule tables as
947 ** appropriate.
948 */
949 
950 static int
951 tzparse(timezone_t sp, const char *name, const int lastditch)
952 {
953 	const char *			stdname;
954 	const char *			dstname;
955 	size_t				stdlen;
956 	size_t				dstlen;
957 	long				stdoffset;
958 	long				dstoffset;
959 	time_t *		atp;
960 	unsigned char *	typep;
961 	char *			cp;
962 	int			load_result;
963 
964 	INITIALIZE(dstname);
965 	stdname = name;
966 	if (lastditch) {
967 		stdlen = strlen(name);	/* length of standard zone name */
968 		name += stdlen;
969 		if (stdlen >= sizeof sp->chars)
970 			stdlen = (sizeof sp->chars) - 1;
971 		stdoffset = 0;
972 	} else {
973 		if (*name == '<') {
974 			name++;
975 			stdname = name;
976 			name = getqzname(name, '>');
977 			if (*name != '>')
978 				return (-1);
979 			stdlen = name - stdname;
980 			name++;
981 		} else {
982 			name = getzname(name);
983 			stdlen = name - stdname;
984 		}
985 		if (*name == '\0')
986 			return -1;
987 		name = getoffset(name, &stdoffset);
988 		if (name == NULL)
989 			return -1;
990 	}
991 	load_result = tzload(sp, TZDEFRULES, FALSE);
992 	if (load_result != 0)
993 		sp->leapcnt = 0;		/* so, we're off a little */
994 	if (*name != '\0') {
995 		if (*name == '<') {
996 			dstname = ++name;
997 			name = getqzname(name, '>');
998 			if (*name != '>')
999 				return -1;
1000 			dstlen = name - dstname;
1001 			name++;
1002 		} else {
1003 			dstname = name;
1004 			name = getzname(name);
1005 			dstlen = name - dstname; /* length of DST zone name */
1006 		}
1007 		if (*name != '\0' && *name != ',' && *name != ';') {
1008 			name = getoffset(name, &dstoffset);
1009 			if (name == NULL)
1010 				return -1;
1011 		} else	dstoffset = stdoffset - SECSPERHOUR;
1012 		if (*name == '\0' && load_result != 0)
1013 			name = TZDEFRULESTRING;
1014 		if (*name == ',' || *name == ';') {
1015 			struct rule	start;
1016 			struct rule	end;
1017 			int	year;
1018 			time_t	janfirst;
1019 			time_t		starttime;
1020 			time_t		endtime;
1021 
1022 			++name;
1023 			if ((name = getrule(name, &start)) == NULL)
1024 				return -1;
1025 			if (*name++ != ',')
1026 				return -1;
1027 			if ((name = getrule(name, &end)) == NULL)
1028 				return -1;
1029 			if (*name != '\0')
1030 				return -1;
1031 			sp->typecnt = 2;	/* standard time and DST */
1032 			/*
1033 			** Two transitions per year, from EPOCH_YEAR forward.
1034 			*/
1035 			memset(sp->ttis, 0, sizeof(sp->ttis));
1036 			sp->ttis[0].tt_gmtoff = -dstoffset;
1037 			sp->ttis[0].tt_isdst = 1;
1038 			sp->ttis[0].tt_abbrind = (int)(stdlen + 1);
1039 			sp->ttis[1].tt_gmtoff = -stdoffset;
1040 			sp->ttis[1].tt_isdst = 0;
1041 			sp->ttis[1].tt_abbrind = 0;
1042 			atp = sp->ats;
1043 			typep = sp->types;
1044 			janfirst = 0;
1045 			sp->timecnt = 0;
1046 			for (year = EPOCH_YEAR;
1047 			    sp->timecnt + 2 <= TZ_MAX_TIMES;
1048 			    ++year) {
1049 			    	time_t	newfirst;
1050 
1051 				starttime = transtime(janfirst, year, &start,
1052 					stdoffset);
1053 				endtime = transtime(janfirst, year, &end,
1054 					dstoffset);
1055 				if (starttime > endtime) {
1056 					*atp++ = endtime;
1057 					*typep++ = 1;	/* DST ends */
1058 					*atp++ = starttime;
1059 					*typep++ = 0;	/* DST begins */
1060 				} else {
1061 					*atp++ = starttime;
1062 					*typep++ = 0;	/* DST begins */
1063 					*atp++ = endtime;
1064 					*typep++ = 1;	/* DST ends */
1065 				}
1066 				sp->timecnt += 2;
1067 				newfirst = janfirst;
1068 				newfirst += (time_t)
1069 				    (year_lengths[isleap(year)] * SECSPERDAY);
1070 				if (newfirst <= janfirst)
1071 					break;
1072 				janfirst = newfirst;
1073 			}
1074 		} else {
1075 			long	theirstdoffset;
1076 			long	theirdstoffset;
1077 			long	theiroffset;
1078 			int	isdst;
1079 			int	i;
1080 			int	j;
1081 
1082 			if (*name != '\0')
1083 				return -1;
1084 			/*
1085 			** Initial values of theirstdoffset and theirdstoffset.
1086 			*/
1087 			theirstdoffset = 0;
1088 			for (i = 0; i < sp->timecnt; ++i) {
1089 				j = sp->types[i];
1090 				if (!sp->ttis[j].tt_isdst) {
1091 					theirstdoffset =
1092 						-sp->ttis[j].tt_gmtoff;
1093 					break;
1094 				}
1095 			}
1096 			theirdstoffset = 0;
1097 			for (i = 0; i < sp->timecnt; ++i) {
1098 				j = sp->types[i];
1099 				if (sp->ttis[j].tt_isdst) {
1100 					theirdstoffset =
1101 						-sp->ttis[j].tt_gmtoff;
1102 					break;
1103 				}
1104 			}
1105 			/*
1106 			** Initially we're assumed to be in standard time.
1107 			*/
1108 			isdst = FALSE;
1109 			theiroffset = theirstdoffset;
1110 			/*
1111 			** Now juggle transition times and types
1112 			** tracking offsets as you do.
1113 			*/
1114 			for (i = 0; i < sp->timecnt; ++i) {
1115 				j = sp->types[i];
1116 				sp->types[i] = sp->ttis[j].tt_isdst;
1117 				if (sp->ttis[j].tt_ttisgmt) {
1118 					/* No adjustment to transition time */
1119 				} else {
1120 					/*
1121 					** If summer time is in effect, and the
1122 					** transition time was not specified as
1123 					** standard time, add the summer time
1124 					** offset to the transition time;
1125 					** otherwise, add the standard time
1126 					** offset to the transition time.
1127 					*/
1128 					/*
1129 					** Transitions from DST to DDST
1130 					** will effectively disappear since
1131 					** POSIX provides for only one DST
1132 					** offset.
1133 					*/
1134 					if (isdst && !sp->ttis[j].tt_ttisstd) {
1135 						sp->ats[i] += (time_t)
1136 						    (dstoffset - theirdstoffset);
1137 					} else {
1138 						sp->ats[i] += (time_t)
1139 						    (stdoffset - theirstdoffset);
1140 					}
1141 				}
1142 				theiroffset = -sp->ttis[j].tt_gmtoff;
1143 				if (!sp->ttis[j].tt_isdst)
1144 					theirstdoffset = theiroffset;
1145 				else	theirdstoffset = theiroffset;
1146 			}
1147 			/*
1148 			** Finally, fill in ttis.
1149 			** ttisstd and ttisgmt need not be handled
1150 			*/
1151 			memset(sp->ttis, 0, sizeof(sp->ttis));
1152 			sp->ttis[0].tt_gmtoff = -stdoffset;
1153 			sp->ttis[0].tt_isdst = FALSE;
1154 			sp->ttis[0].tt_abbrind = 0;
1155 			sp->ttis[1].tt_gmtoff = -dstoffset;
1156 			sp->ttis[1].tt_isdst = TRUE;
1157 			sp->ttis[1].tt_abbrind = (int)(stdlen + 1);
1158 			sp->typecnt = 2;
1159 		}
1160 	} else {
1161 		dstlen = 0;
1162 		sp->typecnt = 1;		/* only standard time */
1163 		sp->timecnt = 0;
1164 		memset(sp->ttis, 0, sizeof(sp->ttis));
1165 		sp->ttis[0].tt_gmtoff = -stdoffset;
1166 		sp->ttis[0].tt_isdst = 0;
1167 		sp->ttis[0].tt_abbrind = 0;
1168 	}
1169 	sp->charcnt = (int)(stdlen + 1);
1170 	if (dstlen != 0)
1171 		sp->charcnt += (int)(dstlen + 1);
1172 	if ((size_t) sp->charcnt > sizeof sp->chars)
1173 		return -1;
1174 	cp = sp->chars;
1175 	(void) strncpy(cp, stdname, stdlen);
1176 	cp += stdlen;
1177 	*cp++ = '\0';
1178 	if (dstlen != 0) {
1179 		(void) strncpy(cp, dstname, dstlen);
1180 		*(cp + dstlen) = '\0';
1181 	}
1182 	return 0;
1183 }
1184 
1185 static void
1186 gmtload(timezone_t sp)
1187 {
1188 	if (tzload(sp, gmt, TRUE) != 0)
1189 		(void) tzparse(sp, gmt, TRUE);
1190 }
1191 
1192 timezone_t
1193 tzalloc(const char *name)
1194 {
1195 	timezone_t sp = calloc(1, sizeof *sp);
1196 	if (sp == NULL)
1197 		return NULL;
1198 	if (tzload(sp, name, TRUE) != 0) {
1199 		free(sp);
1200 		return NULL;
1201 	}
1202 	settzname_z(sp);
1203 	return sp;
1204 }
1205 
1206 void
1207 tzfree(const timezone_t sp)
1208 {
1209 	free(sp);
1210 }
1211 
1212 static void
1213 tzsetwall_unlocked(void)
1214 {
1215 	if (lcl_is_set < 0)
1216 		return;
1217 	lcl_is_set = -1;
1218 
1219 	if (lclptr == NULL) {
1220 		int saveerrno = errno;
1221 		lclptr = calloc(1, sizeof *lclptr);
1222 		errno = saveerrno;
1223 		if (lclptr == NULL) {
1224 			settzname();	/* all we can do */
1225 			return;
1226 		}
1227 	}
1228 	if (tzload(lclptr, NULL, TRUE) != 0)
1229 		gmtload(lclptr);
1230 	settzname();
1231 }
1232 
1233 #ifndef STD_INSPIRED
1234 /*
1235 ** A non-static declaration of tzsetwall in a system header file
1236 ** may cause a warning about this upcoming static declaration...
1237 */
1238 static
1239 #endif /* !defined STD_INSPIRED */
1240 void
1241 tzsetwall(void)
1242 {
1243 	rwlock_wrlock(&lcl_lock);
1244 	tzsetwall_unlocked();
1245 	rwlock_unlock(&lcl_lock);
1246 }
1247 
1248 #ifndef STD_INSPIRED
1249 /*
1250 ** A non-static declaration of tzsetwall in a system header file
1251 ** may cause a warning about this upcoming static declaration...
1252 */
1253 static
1254 #endif /* !defined STD_INSPIRED */
1255 void
1256 tzset_unlocked(void)
1257 {
1258 	const char *	name;
1259 
1260 	name = getenv("TZ");
1261 	if (name == NULL) {
1262 		tzsetwall_unlocked();
1263 		return;
1264 	}
1265 
1266 	if (lcl_is_set > 0 && strcmp(lcl_TZname, name) == 0)
1267 		return;
1268 	lcl_is_set = strlen(name) < sizeof lcl_TZname;
1269 	if (lcl_is_set)
1270 		(void)strlcpy(lcl_TZname, name, sizeof(lcl_TZname));
1271 
1272 	if (lclptr == NULL) {
1273 		int saveerrno = errno;
1274 		lclptr = calloc(1, sizeof *lclptr);
1275 		errno = saveerrno;
1276 		if (lclptr == NULL) {
1277 			settzname();	/* all we can do */
1278 			return;
1279 		}
1280 	}
1281 	if (*name == '\0') {
1282 		/*
1283 		** User wants it fast rather than right.
1284 		*/
1285 		lclptr->leapcnt = 0;		/* so, we're off a little */
1286 		lclptr->timecnt = 0;
1287 		lclptr->typecnt = 0;
1288 		lclptr->ttis[0].tt_isdst = 0;
1289 		lclptr->ttis[0].tt_gmtoff = 0;
1290 		lclptr->ttis[0].tt_abbrind = 0;
1291 		(void) strlcpy(lclptr->chars, gmt, sizeof(lclptr->chars));
1292 	} else if (tzload(lclptr, name, TRUE) != 0)
1293 		if (name[0] == ':' || tzparse(lclptr, name, FALSE) != 0)
1294 			(void) gmtload(lclptr);
1295 	settzname();
1296 }
1297 
1298 void
1299 tzset(void)
1300 {
1301 	rwlock_wrlock(&lcl_lock);
1302 	tzset_unlocked();
1303 	rwlock_unlock(&lcl_lock);
1304 }
1305 
1306 /*
1307 ** The easy way to behave "as if no library function calls" localtime
1308 ** is to not call it--so we drop its guts into "localsub", which can be
1309 ** freely called. (And no, the PANS doesn't require the above behavior--
1310 ** but it *is* desirable.)
1311 **
1312 ** The unused offset argument is for the benefit of mktime variants.
1313 */
1314 
1315 /*ARGSUSED*/
1316 static struct tm *
1317 localsub(const timezone_t sp, const time_t * const timep, const long offset,
1318     struct tm *const tmp)
1319 {
1320 	const struct ttinfo *	ttisp;
1321 	int			i;
1322 	struct tm *		result;
1323 	const time_t			t = *timep;
1324 
1325 	if ((sp->goback && t < sp->ats[0]) ||
1326 		(sp->goahead && t > sp->ats[sp->timecnt - 1])) {
1327 			time_t			newt = t;
1328 			time_t		seconds;
1329 			time_t		tcycles;
1330 			int_fast64_t	icycles;
1331 
1332 			if (t < sp->ats[0])
1333 				seconds = sp->ats[0] - t;
1334 			else	seconds = t - sp->ats[sp->timecnt - 1];
1335 			--seconds;
1336 			tcycles = (time_t)
1337 			    (seconds / YEARSPERREPEAT / AVGSECSPERYEAR);
1338 			++tcycles;
1339 			icycles = tcycles;
1340 			if (tcycles - icycles >= 1 || icycles - tcycles >= 1)
1341 				return NULL;
1342 			seconds = (time_t) icycles;
1343 			seconds *= YEARSPERREPEAT;
1344 			seconds *= AVGSECSPERYEAR;
1345 			if (t < sp->ats[0])
1346 				newt += seconds;
1347 			else	newt -= seconds;
1348 			if (newt < sp->ats[0] ||
1349 				newt > sp->ats[sp->timecnt - 1])
1350 					return NULL;	/* "cannot happen" */
1351 			result = localsub(sp, &newt, offset, tmp);
1352 			if (result == tmp) {
1353 				time_t	newy;
1354 
1355 				newy = tmp->tm_year;
1356 				if (t < sp->ats[0])
1357 					newy -= (time_t)icycles * YEARSPERREPEAT;
1358 				else	newy += (time_t)icycles * YEARSPERREPEAT;
1359 				tmp->tm_year = (int)newy;
1360 				if (tmp->tm_year != newy)
1361 					return NULL;
1362 			}
1363 			return result;
1364 	}
1365 	if (sp->timecnt == 0 || t < sp->ats[0]) {
1366 		i = 0;
1367 		while (sp->ttis[i].tt_isdst)
1368 			if (++i >= sp->typecnt) {
1369 				i = 0;
1370 				break;
1371 			}
1372 	} else {
1373 		int	lo = 1;
1374 		int	hi = sp->timecnt;
1375 
1376 		while (lo < hi) {
1377 			int	mid = (lo + hi) / 2;
1378 
1379 			if (t < sp->ats[mid])
1380 				hi = mid;
1381 			else	lo = mid + 1;
1382 		}
1383 		i = (int) sp->types[lo - 1];
1384 	}
1385 	ttisp = &sp->ttis[i];
1386 	/*
1387 	** To get (wrong) behavior that's compatible with System V Release 2.0
1388 	** you'd replace the statement below with
1389 	**	t += ttisp->tt_gmtoff;
1390 	**	timesub(&t, 0L, sp, tmp);
1391 	*/
1392 	result = timesub(sp, &t, ttisp->tt_gmtoff, tmp);
1393 	tmp->tm_isdst = ttisp->tt_isdst;
1394 	if (sp == lclptr)
1395 		tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
1396 #ifdef TM_ZONE
1397 	tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
1398 #endif /* defined TM_ZONE */
1399 	return result;
1400 }
1401 
1402 /*
1403 ** Re-entrant version of localtime.
1404 */
1405 
1406 struct tm *
1407 localtime_r(const time_t * __restrict timep, struct tm *tmp)
1408 {
1409 	rwlock_rdlock(&lcl_lock);
1410 	tzset_unlocked();
1411 	tmp = localtime_rz(lclptr, timep, tmp);
1412 	rwlock_unlock(&lcl_lock);
1413 	return tmp;
1414 }
1415 
1416 struct tm *
1417 localtime(const time_t *const timep)
1418 {
1419 	return localtime_r(timep, &tm);
1420 }
1421 
1422 struct tm *
1423 localtime_rz(const timezone_t sp, const time_t * __restrict timep, struct tm *tmp)
1424 {
1425 	if (sp == NULL)
1426 		tmp = gmtsub(NULL, timep, 0L, tmp);
1427 	else
1428 		tmp = localsub(sp, timep, 0L, tmp);
1429 	if (tmp == NULL)
1430 		errno = EOVERFLOW;
1431 	return tmp;
1432 }
1433 
1434 /*
1435 ** gmtsub is to gmtime as localsub is to localtime.
1436 */
1437 
1438 static struct tm *
1439 gmtsub(const timezone_t sp, const time_t *const timep, const long offset,
1440     struct tm *const tmp)
1441 {
1442 	struct tm *	result;
1443 #ifdef _REENTRANT
1444 	static mutex_t gmt_mutex = MUTEX_INITIALIZER;
1445 #endif
1446 
1447 	mutex_lock(&gmt_mutex);
1448 	if (!gmt_is_set) {
1449 		int saveerrno;
1450 		gmt_is_set = TRUE;
1451 		saveerrno = errno;
1452 		gmtptr = calloc(1, sizeof *gmtptr);
1453 		errno = saveerrno;
1454 		if (gmtptr != NULL)
1455 			gmtload(gmtptr);
1456 	}
1457 	mutex_unlock(&gmt_mutex);
1458 	result = timesub(gmtptr, timep, offset, tmp);
1459 #ifdef TM_ZONE
1460 	/*
1461 	** Could get fancy here and deliver something such as
1462 	** "UTC+xxxx" or "UTC-xxxx" if offset is non-zero,
1463 	** but this is no time for a treasure hunt.
1464 	*/
1465 	if (offset != 0)
1466 		tmp->TM_ZONE = (__aconst char *)__UNCONST(wildabbr);
1467 	else {
1468 		if (gmtptr == NULL)
1469 			tmp->TM_ZONE = (__aconst char *)__UNCONST(gmt);
1470 		else	tmp->TM_ZONE = gmtptr->chars;
1471 	}
1472 #endif /* defined TM_ZONE */
1473 	return result;
1474 }
1475 
1476 struct tm *
1477 gmtime(const time_t *const timep)
1478 {
1479 	struct tm *tmp = gmtsub(NULL, timep, 0L, &tm);
1480 
1481 	if (tmp == NULL)
1482 		errno = EOVERFLOW;
1483 
1484 	return tmp;
1485 }
1486 
1487 /*
1488 ** Re-entrant version of gmtime.
1489 */
1490 
1491 struct tm *
1492 gmtime_r(const time_t * const timep, struct tm *tmp)
1493 {
1494 	tmp = gmtsub(NULL, timep, 0L, tmp);
1495 
1496 	if (tmp == NULL)
1497 		errno = EOVERFLOW;
1498 
1499 	return tmp;
1500 }
1501 
1502 #ifdef STD_INSPIRED
1503 
1504 struct tm *
1505 offtime(const time_t *const timep, long offset)
1506 {
1507 	struct tm *tmp = gmtsub(NULL, timep, offset, &tm);
1508 
1509 	if (tmp == NULL)
1510 		errno = EOVERFLOW;
1511 
1512 	return tmp;
1513 }
1514 
1515 struct tm *
1516 offtime_r(const time_t *timep, long offset, struct tm *tmp)
1517 {
1518 	tmp = gmtsub(NULL, timep, offset, tmp);
1519 
1520 	if (tmp == NULL)
1521 		errno = EOVERFLOW;
1522 
1523 	return tmp;
1524 }
1525 
1526 #endif /* defined STD_INSPIRED */
1527 
1528 /*
1529 ** Return the number of leap years through the end of the given year
1530 ** where, to make the math easy, the answer for year zero is defined as zero.
1531 */
1532 
1533 static int
1534 leaps_thru_end_of(const int y)
1535 {
1536 	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
1537 		-(leaps_thru_end_of(-(y + 1)) + 1);
1538 }
1539 
1540 static struct tm *
1541 timesub(const timezone_t sp, const time_t *const timep, const long offset,
1542     struct tm *const tmp)
1543 {
1544 	const struct lsinfo *	lp;
1545 	time_t			tdays;
1546 	int			idays;	/* unsigned would be so 2003 */
1547 	long			rem;
1548 	int			y;
1549 	const int *		ip;
1550 	long			corr;
1551 	int			hit;
1552 	int			i;
1553 
1554 	corr = 0;
1555 	hit = 0;
1556 	i = (sp == NULL) ? 0 : sp->leapcnt;
1557 	while (--i >= 0) {
1558 		lp = &sp->lsis[i];
1559 		if (*timep >= lp->ls_trans) {
1560 			if (*timep == lp->ls_trans) {
1561 				hit = ((i == 0 && lp->ls_corr > 0) ||
1562 					lp->ls_corr > sp->lsis[i - 1].ls_corr);
1563 				if (hit)
1564 					while (i > 0 &&
1565 						sp->lsis[i].ls_trans ==
1566 						sp->lsis[i - 1].ls_trans + 1 &&
1567 						sp->lsis[i].ls_corr ==
1568 						sp->lsis[i - 1].ls_corr + 1) {
1569 							++hit;
1570 							--i;
1571 					}
1572 			}
1573 			corr = lp->ls_corr;
1574 			break;
1575 		}
1576 	}
1577 	y = EPOCH_YEAR;
1578 	tdays = (time_t)(*timep / SECSPERDAY);
1579 	rem = (long) (*timep - tdays * SECSPERDAY);
1580 	while (tdays < 0 || tdays >= year_lengths[isleap(y)]) {
1581 		int		newy;
1582 		time_t	tdelta;
1583 		int	idelta;
1584 		int	leapdays;
1585 
1586 		tdelta = tdays / DAYSPERLYEAR;
1587 		idelta = (int) tdelta;
1588 		if (tdelta - idelta >= 1 || idelta - tdelta >= 1)
1589 			return NULL;
1590 		if (idelta == 0)
1591 			idelta = (tdays < 0) ? -1 : 1;
1592 		newy = y;
1593 		if (increment_overflow(&newy, idelta))
1594 			return NULL;
1595 		leapdays = leaps_thru_end_of(newy - 1) -
1596 			leaps_thru_end_of(y - 1);
1597 		tdays -= ((time_t) newy - y) * DAYSPERNYEAR;
1598 		tdays -= leapdays;
1599 		y = newy;
1600 	}
1601 	{
1602 		long	seconds;
1603 
1604 		seconds = tdays * SECSPERDAY + 0.5;
1605 		tdays = (time_t)(seconds / SECSPERDAY);
1606 		rem += (long) (seconds - tdays * SECSPERDAY);
1607 	}
1608 	/*
1609 	** Given the range, we can now fearlessly cast...
1610 	*/
1611 	idays = (int) tdays;
1612 	rem += offset - corr;
1613 	while (rem < 0) {
1614 		rem += SECSPERDAY;
1615 		--idays;
1616 	}
1617 	while (rem >= SECSPERDAY) {
1618 		rem -= SECSPERDAY;
1619 		++idays;
1620 	}
1621 	while (idays < 0) {
1622 		if (increment_overflow(&y, -1))
1623 			return NULL;
1624 		idays += year_lengths[isleap(y)];
1625 	}
1626 	while (idays >= year_lengths[isleap(y)]) {
1627 		idays -= year_lengths[isleap(y)];
1628 		if (increment_overflow(&y, 1))
1629 			return NULL;
1630 	}
1631 	tmp->tm_year = y;
1632 	if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE))
1633 		return NULL;
1634 	tmp->tm_yday = idays;
1635 	/*
1636 	** The "extra" mods below avoid overflow problems.
1637 	*/
1638 	tmp->tm_wday = EPOCH_WDAY +
1639 		((y - EPOCH_YEAR) % DAYSPERWEEK) *
1640 		(DAYSPERNYEAR % DAYSPERWEEK) +
1641 		leaps_thru_end_of(y - 1) -
1642 		leaps_thru_end_of(EPOCH_YEAR - 1) +
1643 		idays;
1644 	tmp->tm_wday %= DAYSPERWEEK;
1645 	if (tmp->tm_wday < 0)
1646 		tmp->tm_wday += DAYSPERWEEK;
1647 	tmp->tm_hour = (int) (rem / SECSPERHOUR);
1648 	rem %= SECSPERHOUR;
1649 	tmp->tm_min = (int) (rem / SECSPERMIN);
1650 	/*
1651 	** A positive leap second requires a special
1652 	** representation. This uses "... ??:59:60" et seq.
1653 	*/
1654 	tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
1655 	ip = mon_lengths[isleap(y)];
1656 	for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
1657 		idays -= ip[tmp->tm_mon];
1658 	tmp->tm_mday = (int) (idays + 1);
1659 	tmp->tm_isdst = 0;
1660 #ifdef TM_GMTOFF
1661 	tmp->TM_GMTOFF = offset;
1662 #endif /* defined TM_GMTOFF */
1663 	return tmp;
1664 }
1665 
1666 char *
1667 ctime(const time_t *const timep)
1668 {
1669 /*
1670 ** Section 4.12.3.2 of X3.159-1989 requires that
1671 **	The ctime function converts the calendar time pointed to by timer
1672 **	to local time in the form of a string. It is equivalent to
1673 **		asctime(localtime(timer))
1674 */
1675 	struct tm *rtm = localtime(timep);
1676 	if (rtm == NULL)
1677 		return NULL;
1678 	return asctime(rtm);
1679 }
1680 
1681 char *
1682 ctime_r(const time_t *const timep, char *buf)
1683 {
1684 	struct tm	mytm, *rtm;
1685 
1686 	rtm = localtime_r(timep, &mytm);
1687 	if (rtm == NULL)
1688 		return NULL;
1689 	return asctime_r(rtm, buf);
1690 }
1691 
1692 char *
1693 ctime_rz(const timezone_t sp, const time_t * timep, char *buf)
1694 {
1695 	struct tm	mytm, *rtm;
1696 
1697 	rtm = localtime_rz(sp, timep, &mytm);
1698 	if (rtm == NULL)
1699 		return NULL;
1700 	return asctime_r(rtm, buf);
1701 }
1702 
1703 /*
1704 ** Adapted from code provided by Robert Elz, who writes:
1705 **	The "best" way to do mktime I think is based on an idea of Bob
1706 **	Kridle's (so its said...) from a long time ago.
1707 **	It does a binary search of the time_t space. Since time_t's are
1708 **	just 32 bits, its a max of 32 iterations (even at 64 bits it
1709 **	would still be very reasonable).
1710 */
1711 
1712 #ifndef WRONG
1713 #define WRONG	((time_t)-1)
1714 #endif /* !defined WRONG */
1715 
1716 /*
1717 ** Simplified normalize logic courtesy Paul Eggert.
1718 */
1719 
1720 static int
1721 increment_overflow(int *const ip, int j)
1722 {
1723 	int	i = *ip;
1724 
1725 	/*
1726 	** If i >= 0 there can only be overflow if i + j > INT_MAX
1727 	** or if j > INT_MAX - i; given i >= 0, INT_MAX - i cannot overflow.
1728 	** If i < 0 there can only be overflow if i + j < INT_MIN
1729 	** or if j < INT_MIN - i; given i < 0, INT_MIN - i cannot overflow.
1730 	*/
1731 	if ((i >= 0) ? (j > INT_MAX - i) : (j < INT_MIN - i))
1732 		return TRUE;
1733 	*ip += j;
1734 	return FALSE;
1735 }
1736 
1737 static int
1738 long_increment_overflow(long *const lp, int m)
1739 {
1740 	long l = *lp;
1741 
1742 	if ((l >= 0) ? (m > LONG_MAX - l) : (m < LONG_MIN - l))
1743 		return TRUE;
1744 	*lp += m;
1745 	return FALSE;
1746 }
1747 
1748 static int
1749 normalize_overflow(int *const tensptr, int *const unitsptr, const int base)
1750 {
1751 	int	tensdelta;
1752 
1753 	tensdelta = (*unitsptr >= 0) ?
1754 		(*unitsptr / base) :
1755 		(-1 - (-1 - *unitsptr) / base);
1756 	*unitsptr -= tensdelta * base;
1757 	return increment_overflow(tensptr, tensdelta);
1758 }
1759 
1760 static int
1761 long_normalize_overflow(long *const tensptr, int *const unitsptr,
1762     const int base)
1763 {
1764 	int	tensdelta;
1765 
1766 	tensdelta = (*unitsptr >= 0) ?
1767 		(*unitsptr / base) :
1768 		(-1 - (-1 - *unitsptr) / base);
1769 	*unitsptr -= tensdelta * base;
1770 	return long_increment_overflow(tensptr, tensdelta);
1771 }
1772 
1773 static int
1774 tmcomp(const struct tm *const atmp, const struct tm *const btmp)
1775 {
1776 	int	result;
1777 
1778 	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
1779 		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
1780 		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
1781 		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
1782 		(result = (atmp->tm_min - btmp->tm_min)) == 0)
1783 			result = atmp->tm_sec - btmp->tm_sec;
1784 	return result;
1785 }
1786 
1787 static time_t
1788 time2sub(const timezone_t sp, struct tm *const tmp, subfun_t funcp,
1789     const long offset, int *const okayp, const int do_norm_secs)
1790 {
1791 	int			dir;
1792 	int			i, j;
1793 	int			saved_seconds;
1794 	long			li;
1795 	time_t			lo;
1796 	time_t			hi;
1797 #ifdef NO_ERROR_IN_DST_GAP
1798 	time_t			ilo;
1799 #endif
1800 	long				y;
1801 	time_t				newt;
1802 	time_t				t;
1803 	struct tm			yourtm, mytm;
1804 
1805 	*okayp = FALSE;
1806 	yourtm = *tmp;
1807 #ifdef NO_ERROR_IN_DST_GAP
1808 again:
1809 #endif
1810 	if (do_norm_secs) {
1811 		if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
1812 		    SECSPERMIN))
1813 			goto overflow;
1814 	}
1815 	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
1816 		goto overflow;
1817 	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
1818 		goto overflow;
1819 	y = yourtm.tm_year;
1820 	if (long_normalize_overflow(&y, &yourtm.tm_mon, MONSPERYEAR))
1821 		goto overflow;
1822 	/*
1823 	** Turn y into an actual year number for now.
1824 	** It is converted back to an offset from TM_YEAR_BASE later.
1825 	*/
1826 	if (long_increment_overflow(&y, TM_YEAR_BASE))
1827 		goto overflow;
1828 	while (yourtm.tm_mday <= 0) {
1829 		if (long_increment_overflow(&y, -1))
1830 			goto overflow;
1831 		li = y + (1 < yourtm.tm_mon);
1832 		yourtm.tm_mday += year_lengths[isleap(li)];
1833 	}
1834 	while (yourtm.tm_mday > DAYSPERLYEAR) {
1835 		li = y + (1 < yourtm.tm_mon);
1836 		yourtm.tm_mday -= year_lengths[isleap(li)];
1837 		if (long_increment_overflow(&y, 1))
1838 			goto overflow;
1839 	}
1840 	for ( ; ; ) {
1841 		i = mon_lengths[isleap(y)][yourtm.tm_mon];
1842 		if (yourtm.tm_mday <= i)
1843 			break;
1844 		yourtm.tm_mday -= i;
1845 		if (++yourtm.tm_mon >= MONSPERYEAR) {
1846 			yourtm.tm_mon = 0;
1847 			if (long_increment_overflow(&y, 1))
1848 				goto overflow;
1849 		}
1850 	}
1851 	if (long_increment_overflow(&y, -TM_YEAR_BASE))
1852 		goto overflow;
1853 	yourtm.tm_year = (int)y;
1854 	if (yourtm.tm_year != y)
1855 		goto overflow;
1856 	if (yourtm.tm_sec >= 0 && yourtm.tm_sec < SECSPERMIN)
1857 		saved_seconds = 0;
1858 	else if (y + TM_YEAR_BASE < EPOCH_YEAR) {
1859 		/*
1860 		** We can't set tm_sec to 0, because that might push the
1861 		** time below the minimum representable time.
1862 		** Set tm_sec to 59 instead.
1863 		** This assumes that the minimum representable time is
1864 		** not in the same minute that a leap second was deleted from,
1865 		** which is a safer assumption than using 58 would be.
1866 		*/
1867 		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
1868 			goto overflow;
1869 		saved_seconds = yourtm.tm_sec;
1870 		yourtm.tm_sec = SECSPERMIN - 1;
1871 	} else {
1872 		saved_seconds = yourtm.tm_sec;
1873 		yourtm.tm_sec = 0;
1874 	}
1875 	/*
1876 	** Do a binary search (this works whatever time_t's type is).
1877 	*/
1878 	/* LINTED const not */
1879 	if (!TYPE_SIGNED(time_t)) {
1880 		lo = 0;
1881 		hi = lo - 1;
1882 	/* LINTED const not */
1883 	} else if (!TYPE_INTEGRAL(time_t)) {
1884 		/* CONSTCOND */
1885 		if (sizeof(time_t) > sizeof(float))
1886 			/* LINTED assumed double */
1887 			hi = (time_t) DBL_MAX;
1888 			/* LINTED assumed float */
1889 		else	hi = (time_t) FLT_MAX;
1890 		lo = -hi;
1891 	} else {
1892 		lo = 1;
1893 		for (i = 0; i < (int) TYPE_BIT(time_t) - 1; ++i)
1894 			lo *= 2;
1895 		hi = -(lo + 1);
1896 	}
1897 #ifdef NO_ERROR_IN_DST_GAP
1898 	ilo = lo;
1899 #endif
1900 	for ( ; ; ) {
1901 		t = lo / 2 + hi / 2;
1902 		if (t < lo)
1903 			t = lo;
1904 		else if (t > hi)
1905 			t = hi;
1906 		if ((*funcp)(sp, &t, offset, &mytm) == NULL) {
1907 			/*
1908 			** Assume that t is too extreme to be represented in
1909 			** a struct tm; arrange things so that it is less
1910 			** extreme on the next pass.
1911 			*/
1912 			dir = (t > 0) ? 1 : -1;
1913 		} else	dir = tmcomp(&mytm, &yourtm);
1914 		if (dir != 0) {
1915 			if (t == lo) {
1916 				++t;
1917 				if (t <= lo)
1918 					goto overflow;
1919 				++lo;
1920 			} else if (t == hi) {
1921 				--t;
1922 				if (t >= hi)
1923 					goto overflow;
1924 				--hi;
1925 			}
1926 #ifdef NO_ERROR_IN_DST_GAP
1927 			if (ilo != lo && lo - 1 == hi && yourtm.tm_isdst < 0 &&
1928 			    do_norm_secs) {
1929 				for (i = sp->typecnt - 1; i >= 0; --i) {
1930 					for (j = sp->typecnt - 1; j >= 0; --j) {
1931 						time_t off;
1932 						if (sp->ttis[j].tt_isdst ==
1933 						    sp->ttis[i].tt_isdst)
1934 							continue;
1935 						off = sp->ttis[j].tt_gmtoff -
1936 						    sp->ttis[i].tt_gmtoff;
1937 						yourtm.tm_sec += off < 0 ?
1938 						    -off : off;
1939 						goto again;
1940 					}
1941 				}
1942 			}
1943 #endif
1944 			if (lo > hi)
1945 				goto invalid;
1946 			if (dir > 0)
1947 				hi = t;
1948 			else	lo = t;
1949 			continue;
1950 		}
1951 		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
1952 			break;
1953 		/*
1954 		** Right time, wrong type.
1955 		** Hunt for right time, right type.
1956 		** It's okay to guess wrong since the guess
1957 		** gets checked.
1958 		*/
1959 		if (sp == NULL)
1960 			goto invalid;
1961 		for (i = sp->typecnt - 1; i >= 0; --i) {
1962 			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
1963 				continue;
1964 			for (j = sp->typecnt - 1; j >= 0; --j) {
1965 				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
1966 					continue;
1967 				newt = (time_t)(t + sp->ttis[j].tt_gmtoff -
1968 				    sp->ttis[i].tt_gmtoff);
1969 				if ((*funcp)(sp, &newt, offset, &mytm) == NULL)
1970 					continue;
1971 				if (tmcomp(&mytm, &yourtm) != 0)
1972 					continue;
1973 				if (mytm.tm_isdst != yourtm.tm_isdst)
1974 					continue;
1975 				/*
1976 				** We have a match.
1977 				*/
1978 				t = newt;
1979 				goto label;
1980 			}
1981 		}
1982 		goto invalid;
1983 	}
1984 label:
1985 	newt = t + saved_seconds;
1986 	if ((newt < t) != (saved_seconds < 0))
1987 		goto overflow;
1988 	t = newt;
1989 	if ((*funcp)(sp, &t, offset, tmp)) {
1990 		*okayp = TRUE;
1991 		return t;
1992 	}
1993 overflow:
1994 	errno = EOVERFLOW;
1995 	return WRONG;
1996 invalid:
1997 	errno = EINVAL;
1998 	return WRONG;
1999 }
2000 
2001 static time_t
2002 time2(const timezone_t sp, struct tm *const tmp, subfun_t funcp,
2003     const long offset, int *const okayp)
2004 {
2005 	time_t	t;
2006 
2007 	/*
2008 	** First try without normalization of seconds
2009 	** (in case tm_sec contains a value associated with a leap second).
2010 	** If that fails, try with normalization of seconds.
2011 	*/
2012 	t = time2sub(sp, tmp, funcp, offset, okayp, FALSE);
2013 	return *okayp ? t : time2sub(sp, tmp, funcp, offset, okayp, TRUE);
2014 }
2015 
2016 static time_t
2017 time1(const timezone_t sp, struct tm *const tmp, subfun_t funcp,
2018     const long offset)
2019 {
2020 	time_t			t;
2021 	int			samei, otheri;
2022 	int			sameind, otherind;
2023 	int			i;
2024 	int			nseen;
2025 	int				seen[TZ_MAX_TYPES];
2026 	int				types[TZ_MAX_TYPES];
2027 	int				okay;
2028 
2029 	if (tmp == NULL) {
2030 		errno = EINVAL;
2031 		return WRONG;
2032 	}
2033 	if (tmp->tm_isdst > 1)
2034 		tmp->tm_isdst = 1;
2035 	t = time2(sp, tmp, funcp, offset, &okay);
2036 #ifdef PCTS
2037 	/*
2038 	** PCTS code courtesy Grant Sullivan.
2039 	*/
2040 	if (okay)
2041 		return t;
2042 	if (tmp->tm_isdst < 0)
2043 		tmp->tm_isdst = 0;	/* reset to std and try again */
2044 #endif /* defined PCTS */
2045 #ifndef PCTS
2046 	if (okay || tmp->tm_isdst < 0)
2047 		return t;
2048 #endif /* !defined PCTS */
2049 	/*
2050 	** We're supposed to assume that somebody took a time of one type
2051 	** and did some math on it that yielded a "struct tm" that's bad.
2052 	** We try to divine the type they started from and adjust to the
2053 	** type they need.
2054 	*/
2055 	if (sp == NULL) {
2056 		errno = EINVAL;
2057 		return WRONG;
2058 	}
2059 	for (i = 0; i < sp->typecnt; ++i)
2060 		seen[i] = FALSE;
2061 	nseen = 0;
2062 	for (i = sp->timecnt - 1; i >= 0; --i)
2063 		if (!seen[sp->types[i]]) {
2064 			seen[sp->types[i]] = TRUE;
2065 			types[nseen++] = sp->types[i];
2066 		}
2067 	for (sameind = 0; sameind < nseen; ++sameind) {
2068 		samei = types[sameind];
2069 		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
2070 			continue;
2071 		for (otherind = 0; otherind < nseen; ++otherind) {
2072 			otheri = types[otherind];
2073 			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
2074 				continue;
2075 			tmp->tm_sec += (int)(sp->ttis[otheri].tt_gmtoff -
2076 					sp->ttis[samei].tt_gmtoff);
2077 			tmp->tm_isdst = !tmp->tm_isdst;
2078 			t = time2(sp, tmp, funcp, offset, &okay);
2079 			if (okay)
2080 				return t;
2081 			tmp->tm_sec -= (int)(sp->ttis[otheri].tt_gmtoff -
2082 					sp->ttis[samei].tt_gmtoff);
2083 			tmp->tm_isdst = !tmp->tm_isdst;
2084 		}
2085 	}
2086 	errno = EOVERFLOW;
2087 	return WRONG;
2088 }
2089 
2090 time_t
2091 mktime_z(const timezone_t sp, struct tm *const tmp)
2092 {
2093 	time_t t;
2094 	if (sp == NULL)
2095 		t = time1(NULL, tmp, gmtsub, 0L);
2096 	else
2097 		t = time1(sp, tmp, localsub, 0L);
2098 	return t;
2099 }
2100 
2101 time_t
2102 mktime(struct tm *const tmp)
2103 {
2104 	time_t result;
2105 
2106 	rwlock_wrlock(&lcl_lock);
2107 	tzset_unlocked();
2108 	result = mktime_z(lclptr, tmp);
2109 	rwlock_unlock(&lcl_lock);
2110 	return result;
2111 }
2112 
2113 #ifdef STD_INSPIRED
2114 
2115 time_t
2116 timelocal_z(const timezone_t sp, struct tm *const tmp)
2117 {
2118 	if (tmp != NULL)
2119 		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
2120 	return mktime_z(sp, tmp);
2121 }
2122 
2123 time_t
2124 timelocal(struct tm *const tmp)
2125 {
2126 	if (tmp != NULL)
2127 		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
2128 	return mktime(tmp);
2129 }
2130 
2131 time_t
2132 timegm(struct tm *const tmp)
2133 {
2134 	time_t t;
2135 
2136 	if (tmp != NULL)
2137 		tmp->tm_isdst = 0;
2138 	t = time1(gmtptr, tmp, gmtsub, 0L);
2139 	return t;
2140 }
2141 
2142 time_t
2143 timeoff(struct tm *const tmp, const long offset)
2144 {
2145 	time_t t;
2146 
2147 	if (tmp != NULL)
2148 		tmp->tm_isdst = 0;
2149 	t = time1(gmtptr, tmp, gmtsub, offset);
2150 	return t;
2151 }
2152 
2153 #endif /* defined STD_INSPIRED */
2154 
2155 #ifdef CMUCS
2156 
2157 /*
2158 ** The following is supplied for compatibility with
2159 ** previous versions of the CMUCS runtime library.
2160 */
2161 
2162 long
2163 gtime(struct tm *const tmp)
2164 {
2165 	const time_t t = mktime(tmp);
2166 
2167 	if (t == WRONG)
2168 		return -1;
2169 	return t;
2170 }
2171 
2172 #endif /* defined CMUCS */
2173 
2174 /*
2175 ** XXX--is the below the right way to conditionalize??
2176 */
2177 
2178 #ifdef STD_INSPIRED
2179 
2180 /*
2181 ** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
2182 ** shall correspond to "Wed Dec 31 23:59:59 UTC 1986", which
2183 ** is not the case if we are accounting for leap seconds.
2184 ** So, we provide the following conversion routines for use
2185 ** when exchanging timestamps with POSIX conforming systems.
2186 */
2187 
2188 static long
2189 leapcorr(const timezone_t sp, time_t *timep)
2190 {
2191 	struct lsinfo * lp;
2192 	int		i;
2193 
2194 	i = sp->leapcnt;
2195 	while (--i >= 0) {
2196 		lp = &sp->lsis[i];
2197 		if (*timep >= lp->ls_trans)
2198 			return lp->ls_corr;
2199 	}
2200 	return 0;
2201 }
2202 
2203 time_t
2204 time2posix_z(const timezone_t sp, time_t t)
2205 {
2206 	return (time_t)(t - leapcorr(sp, &t));
2207 }
2208 
2209 time_t
2210 time2posix(time_t t)
2211 {
2212 	time_t result;
2213 	rwlock_wrlock(&lcl_lock);
2214 	tzset_unlocked();
2215 	result = (time_t)(t - leapcorr(lclptr, &t));
2216 	rwlock_unlock(&lcl_lock);
2217 	return (result);
2218 }
2219 
2220 time_t
2221 posix2time_z(const timezone_t sp, time_t t)
2222 {
2223 	time_t	x;
2224 	time_t	y;
2225 
2226 	/*
2227 	** For a positive leap second hit, the result
2228 	** is not unique. For a negative leap second
2229 	** hit, the corresponding time doesn't exist,
2230 	** so we return an adjacent second.
2231 	*/
2232 	x = (time_t)(t + leapcorr(sp, &t));
2233 	y = (time_t)(x - leapcorr(sp, &x));
2234 	if (y < t) {
2235 		do {
2236 			x++;
2237 			y = (time_t)(x - leapcorr(sp, &x));
2238 		} while (y < t);
2239 		if (t != y) {
2240 			return x - 1;
2241 		}
2242 	} else if (y > t) {
2243 		do {
2244 			--x;
2245 			y = (time_t)(x - leapcorr(sp, &x));
2246 		} while (y > t);
2247 		if (t != y) {
2248 			return x + 1;
2249 		}
2250 	}
2251 	return x;
2252 }
2253 
2254 
2255 
2256 time_t
2257 posix2time(time_t t)
2258 {
2259 	time_t result;
2260 
2261 	rwlock_wrlock(&lcl_lock);
2262 	tzset_unlocked();
2263 	result = posix2time_z(lclptr, t);
2264 	rwlock_unlock(&lcl_lock);
2265 	return result;
2266 }
2267 
2268 #endif /* defined STD_INSPIRED */
2269