xref: /netbsd-src/lib/libc/time/zdump.c (revision ba65fde2d7fefa7d39838fa5fa855e62bd606b5e)
1 /*	$NetBSD: zdump.c,v 1.27 2013/01/31 15:47:53 christos Exp $	*/
2 /*
3 ** This file is in the public domain, so clarified as of
4 ** 2009-05-17 by Arthur David Olson.
5 */
6 
7 #include <sys/cdefs.h>
8 #ifndef lint
9 __RCSID("$NetBSD: zdump.c,v 1.27 2013/01/31 15:47:53 christos Exp $");
10 #endif /* !defined lint */
11 
12 #include "version.h"
13 /*
14 ** This code has been made independent of the rest of the time
15 ** conversion package to increase confidence in the verification it provides.
16 ** You can use this code to help in verifying other implementations.
17 */
18 
19 #include "stdio.h"	/* for stdout, stderr */
20 #include "string.h"	/* for strcpy */
21 #include "sys/types.h"	/* for time_t */
22 #include "time.h"	/* for struct tm */
23 #include "stdlib.h"	/* for exit, malloc, atoi */
24 #include <err.h>
25 #include "float.h"	/* for FLT_MAX and DBL_MAX */
26 #include "ctype.h"	/* for isalpha et al. */
27 #ifndef isascii
28 #define isascii(x) 1
29 #endif /* !defined isascii */
30 
31 #include "private.h"
32 
33 #ifndef ZDUMP_LO_YEAR
34 #define ZDUMP_LO_YEAR	(-500)
35 #endif /* !defined ZDUMP_LO_YEAR */
36 
37 #ifndef ZDUMP_HI_YEAR
38 #define ZDUMP_HI_YEAR	2500
39 #endif /* !defined ZDUMP_HI_YEAR */
40 
41 #ifndef MAX_STRING_LENGTH
42 #define MAX_STRING_LENGTH	1024
43 #endif /* !defined MAX_STRING_LENGTH */
44 
45 #ifndef TRUE
46 #define TRUE		1
47 #endif /* !defined TRUE */
48 
49 #ifndef FALSE
50 #define FALSE		0
51 #endif /* !defined FALSE */
52 
53 #ifndef EXIT_SUCCESS
54 #define EXIT_SUCCESS	0
55 #endif /* !defined EXIT_SUCCESS */
56 
57 #ifndef EXIT_FAILURE
58 #define EXIT_FAILURE	1
59 #endif /* !defined EXIT_FAILURE */
60 
61 #ifndef SECSPERMIN
62 #define SECSPERMIN	60
63 #endif /* !defined SECSPERMIN */
64 
65 #ifndef MINSPERHOUR
66 #define MINSPERHOUR	60
67 #endif /* !defined MINSPERHOUR */
68 
69 #ifndef SECSPERHOUR
70 #define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
71 #endif /* !defined SECSPERHOUR */
72 
73 #ifndef HOURSPERDAY
74 #define HOURSPERDAY	24
75 #endif /* !defined HOURSPERDAY */
76 
77 #ifndef EPOCH_YEAR
78 #define EPOCH_YEAR	1970
79 #endif /* !defined EPOCH_YEAR */
80 
81 #ifndef TM_YEAR_BASE
82 #define TM_YEAR_BASE	1900
83 #endif /* !defined TM_YEAR_BASE */
84 
85 #ifndef DAYSPERNYEAR
86 #define DAYSPERNYEAR	365
87 #endif /* !defined DAYSPERNYEAR */
88 
89 #ifndef isleap
90 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
91 #endif /* !defined isleap */
92 
93 #ifndef isleap_sum
94 /*
95 ** See tzfile.h for details on isleap_sum.
96 */
97 #define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
98 #endif /* !defined isleap_sum */
99 
100 #define SECSPERDAY	((long) SECSPERHOUR * HOURSPERDAY)
101 #define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
102 #define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
103 
104 #ifndef HAVE_GETTEXT
105 #define HAVE_GETTEXT 0
106 #endif
107 #if HAVE_GETTEXT
108 #include "locale.h"	/* for setlocale */
109 #include "libintl.h"
110 #endif /* HAVE_GETTEXT */
111 
112 #ifndef GNUC_or_lint
113 #ifdef lint
114 #define GNUC_or_lint
115 #else /* !defined lint */
116 #ifdef __GNUC__
117 #define GNUC_or_lint
118 #endif /* defined __GNUC__ */
119 #endif /* !defined lint */
120 #endif /* !defined GNUC_or_lint */
121 
122 #ifndef __pure
123 #if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
124 # define __pure __attribute__ ((__pure__))
125 #else
126 # define __pure /* empty */
127 #endif
128 #endif
129 
130 #ifndef INITIALIZE
131 #ifdef GNUC_or_lint
132 #define INITIALIZE(x)	((x) = 0)
133 #else /* !defined GNUC_or_lint */
134 #define INITIALIZE(x)
135 #endif /* !defined GNUC_or_lint */
136 #endif /* !defined INITIALIZE */
137 
138 /*
139 ** For the benefit of GNU folk...
140 ** `_(MSGID)' uses the current locale's message library string for MSGID.
141 ** The default is to use gettext if available, and use MSGID otherwise.
142 */
143 
144 #ifndef _
145 #if HAVE_GETTEXT
146 #define _(msgid) gettext(msgid)
147 #else /* !HAVE_GETTEXT */
148 #define _(msgid) msgid
149 #endif /* !HAVE_GETTEXT */
150 #endif /* !defined _ */
151 
152 #ifndef TZ_DOMAIN
153 #define TZ_DOMAIN "tz"
154 #endif /* !defined TZ_DOMAIN */
155 
156 extern char **	environ;
157 extern int	getopt(int argc, char * const argv[],
158 			const char * options);
159 extern char *	optarg;
160 extern int	optind;
161 
162 static time_t	absolute_min_time;
163 static time_t	absolute_max_time;
164 static size_t	longest;
165 static char *	progname;
166 static int	warned;
167 
168 static const char *	abbr(struct tm * tmp);
169 static void	abbrok(const char * abbrp, const char * zone);
170 static long	delta(struct tm * newp, struct tm * oldp) __pure;
171 static void	dumptime(const struct tm * tmp);
172 static time_t	hunt(char * name, time_t lot, time_t	hit);
173 int		main(int, char **);
174 static void	setabsolutes(void);
175 static void	show(char * zone, time_t t, int v);
176 static const char *	tformat(void);
177 static time_t	yeartot(long y) __pure;
178 
179 #ifndef TYPECHECK
180 #define my_localtime	localtime
181 #else /* !defined TYPECHECK */
182 static struct tm *
183 my_localtime(time_t *tp)
184 {
185 	struct tm *tmp;
186 
187 	tmp = localtime(tp);
188 	if (tp != NULL && tmp != NULL) {
189 		struct tm	tm;
190 		time_t	t;
191 
192 		tm = *tmp;
193 		t = mktime(&tm);
194 		if (t - *tp >= 1 || *tp - t >= 1) {
195 			(void) fflush(stdout);
196 			(void) fprintf(stderr, "\n%s: ", progname);
197 			(void) fprintf(stderr, tformat(), *tp);
198 			(void) fprintf(stderr, " ->");
199 			(void) fprintf(stderr, " year=%d", tmp->tm_year);
200 			(void) fprintf(stderr, " mon=%d", tmp->tm_mon);
201 			(void) fprintf(stderr, " mday=%d", tmp->tm_mday);
202 			(void) fprintf(stderr, " hour=%d", tmp->tm_hour);
203 			(void) fprintf(stderr, " min=%d", tmp->tm_min);
204 			(void) fprintf(stderr, " sec=%d", tmp->tm_sec);
205 			(void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
206 			(void) fprintf(stderr, " -> ");
207 			(void) fprintf(stderr, tformat(), t);
208 			(void) fprintf(stderr, "\n");
209 		}
210 	}
211 	return tmp;
212 }
213 #endif /* !defined TYPECHECK */
214 
215 static void
216 abbrok(const char *const abbrp, const char *const zone)
217 {
218 	const char *cp;
219 	const char *wp;
220 
221 	if (warned)
222 		return;
223 	cp = abbrp;
224 	wp = NULL;
225 	while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
226 		++cp;
227 	if (cp - abbrp == 0)
228 		wp = _("lacks alphabetic at start");
229 	else if (cp - abbrp < 3)
230 		wp = _("has fewer than 3 alphabetics");
231 	else if (cp - abbrp > 6)
232 		wp = _("has more than 6 alphabetics");
233 	if (wp == NULL && (*cp == '+' || *cp == '-')) {
234 		++cp;
235 		if (isascii((unsigned char) *cp) &&
236 			isdigit((unsigned char) *cp))
237 				if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
238 					++cp;
239 		if (*cp != '\0')
240 			wp = _("differs from POSIX standard");
241 	}
242 	if (wp == NULL)
243 		return;
244 	(void) fflush(stdout);
245 	(void) fprintf(stderr,
246 		_("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
247 		progname, zone, abbrp, wp);
248 	warned = TRUE;
249 }
250 
251 __dead static void
252 usage(FILE *const stream, const int status)
253 {
254 	(void) fprintf(stream,
255 _("%s: usage is %s [ --version ] [ --help ] [ -v ] [ -c [loyear,]hiyear ] zonename ...\n\
256 \n\
257 Report bugs to tz@elsie.nci.nih.gov.\n"),
258 		       progname, progname);
259 	exit(status);
260 }
261 
262 int
263 main(int argc, char *argv[])
264 {
265 	int		i;
266 	int		c;
267 	int		vflag;
268 	char *		cutarg;
269 	long		cutloyear = ZDUMP_LO_YEAR;
270 	long		cuthiyear = ZDUMP_HI_YEAR;
271 	time_t		cutlotime;
272 	time_t		cuthitime;
273 	char **		fakeenv;
274 	time_t		now;
275 	time_t		t;
276 	time_t		newt;
277 	struct tm	tm;
278 	struct tm	newtm;
279 	struct tm *	tmp;
280 	struct tm *	newtmp;
281 
282 	INITIALIZE(cutlotime);
283 	INITIALIZE(cuthitime);
284 #if HAVE_GETTEXT
285 	(void) setlocale(LC_ALL, "");
286 #ifdef TZ_DOMAINDIR
287 	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
288 #endif /* defined TEXTDOMAINDIR */
289 	(void) textdomain(TZ_DOMAIN);
290 #endif /* HAVE_GETTEXT */
291 	progname = argv[0];
292 	for (i = 1; i < argc; ++i)
293 		if (strcmp(argv[i], "--version") == 0) {
294 			(void) printf("%s\n", TZVERSION);
295 			exit(EXIT_SUCCESS);
296 		} else if (strcmp(argv[i], "--help") == 0) {
297 			usage(stdout, EXIT_SUCCESS);
298 		}
299 	vflag = 0;
300 	cutarg = NULL;
301 	while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
302 		if (c == 'v')
303 			vflag = 1;
304 		else	cutarg = optarg;
305 	if ((c != EOF && c != -1) ||
306 		(optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
307 			usage(stderr, EXIT_FAILURE);
308 	}
309 	if (vflag) {
310 		if (cutarg != NULL) {
311 			long	lo;
312 			long	hi;
313 			char	dummy;
314 
315 			if (sscanf(cutarg, "%ld%c", &hi, &dummy) == 1) {
316 				cuthiyear = hi;
317 			} else if (sscanf(cutarg, "%ld,%ld%c",
318 				&lo, &hi, &dummy) == 2) {
319 					cutloyear = lo;
320 					cuthiyear = hi;
321 			} else {
322 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
323 					progname, cutarg);
324 				exit(EXIT_FAILURE);
325 			}
326 		}
327 		setabsolutes();
328 		cutlotime = yeartot(cutloyear);
329 		cuthitime = yeartot(cuthiyear);
330 	}
331 	(void) time(&now);
332 	longest = 0;
333 	for (i = optind; i < argc; ++i)
334 		if (strlen(argv[i]) > longest)
335 			longest = strlen(argv[i]);
336 	{
337 		int	from;
338 		int	to;
339 
340 		for (i = 0; environ[i] != NULL; ++i)
341 			continue;
342 		fakeenv = malloc((i + 2) * sizeof *fakeenv);
343 		if (fakeenv == NULL ||
344 			(fakeenv[0] = malloc(longest + 4)) == NULL) {
345 			err(EXIT_FAILURE, "Can't allocated %zu bytes",
346 			    longest + 4);
347 		}
348 		to = 0;
349 		(void)strcpy(fakeenv[to++], "TZ=");	/* XXX strcpy is safe */
350 		for (from = 0; environ[from] != NULL; ++from)
351 			if (strncmp(environ[from], "TZ=", 3) != 0)
352 				fakeenv[to++] = environ[from];
353 		fakeenv[to] = NULL;
354 		environ = fakeenv;
355 	}
356 	for (i = optind; i < argc; ++i) {
357 		static char	buf[MAX_STRING_LENGTH];
358 
359 		(void) strcpy(&fakeenv[0][3], argv[i]);	/* XXX strcpy is safe */
360 		if (!vflag) {
361 			show(argv[i], now, FALSE);
362 			continue;
363 		}
364 		warned = FALSE;
365 		t = absolute_min_time;
366 		show(argv[i], t, TRUE);
367 		t += SECSPERHOUR * HOURSPERDAY;
368 		show(argv[i], t, TRUE);
369 		if (t < cutlotime)
370 			t = cutlotime;
371 		tmp = my_localtime(&t);
372 		if (tmp != NULL) {
373 			tm = *tmp;
374 			(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
375 		}
376 		for ( ; ; ) {
377 			if (t >= cuthitime || t >= cuthitime - SECSPERHOUR * 12)
378 				break;
379 			newt = t + SECSPERHOUR * 12;
380 			newtmp = localtime(&newt);
381 			if (newtmp != NULL)
382 				newtm = *newtmp;
383 			if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
384 				(delta(&newtm, &tm) != (newt - t) ||
385 				newtm.tm_isdst != tm.tm_isdst ||
386 				strcmp(abbr(&newtm), buf) != 0)) {
387 					newt = hunt(argv[i], t, newt);
388 					newtmp = localtime(&newt);
389 					if (newtmp != NULL) {
390 						newtm = *newtmp;
391 						(void) strncpy(buf,
392 							abbr(&newtm),
393 							(sizeof buf) - 1);
394 					}
395 			}
396 			t = newt;
397 			tm = newtm;
398 			tmp = newtmp;
399 		}
400 		t = absolute_max_time;
401 		t -= SECSPERHOUR * HOURSPERDAY;
402 		show(argv[i], t, TRUE);
403 		t += SECSPERHOUR * HOURSPERDAY;
404 		show(argv[i], t, TRUE);
405 	}
406 	if (fflush(stdout) || ferror(stdout)) {
407 		err(EXIT_FAILURE, _("Error writing standard output"));
408 	}
409 	exit(EXIT_SUCCESS);
410 	/* If exit fails to exit... */
411 	return EXIT_FAILURE;
412 }
413 
414 static time_t
415 ovfl_check(time_t t)
416 {
417 	if (t < 0 && t - 1 >= 0)
418 		return t;
419 	else
420 		return t - 1;
421 }
422 
423 static void
424 setabsolutes(void)
425 {
426 	if (0.5 == (time_t) 0.5) {
427 		/*
428 		** time_t is floating.
429 		*/
430 		if (sizeof (time_t) == sizeof (float)) {
431 			absolute_min_time = (time_t) -FLT_MAX;
432 			absolute_max_time = (time_t) FLT_MAX;
433 		} else if (sizeof (time_t) == sizeof (double)) {
434 			absolute_min_time = (time_t) -DBL_MAX;
435 			absolute_max_time = (time_t) DBL_MAX;
436 		} else {
437 			(void) fprintf(stderr,
438 _("%s: use of -v on system with floating time_t other than float or double\n"),
439 				progname);
440 			exit(EXIT_FAILURE);
441 		}
442 	} else if (0 > (time_t) -1) {
443 		/*
444 		** time_t is signed.  Assume overflow wraps around.
445 		*/
446 		time_t t = 0;
447 		time_t t1 = 1;
448 
449 		while (t < t1) {
450 			t = t1;
451 			t1 = 2 * t1 + 1;
452 		}
453 
454 		absolute_max_time = t;
455 		t = -t;
456 		absolute_min_time = ovfl_check(t);
457 	} else {
458 		/*
459 		** time_t is unsigned.
460 		*/
461 		absolute_min_time = 0;
462 		absolute_max_time = absolute_min_time - 1;
463 	}
464 }
465 
466 static time_t
467 yeartot(const long y)
468 {
469 	long	myy;
470 	long	seconds;
471 	time_t	t;
472 
473 	myy = EPOCH_YEAR;
474 	t = 0;
475 	while (myy != y) {
476 		if (myy < y) {
477 			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
478 			++myy;
479 			if (t > absolute_max_time - seconds) {
480 				t = absolute_max_time;
481 				break;
482 			}
483 			t += seconds;
484 		} else {
485 			--myy;
486 			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
487 			if (t < absolute_min_time + seconds) {
488 				t = absolute_min_time;
489 				break;
490 			}
491 			t -= seconds;
492 		}
493 	}
494 	return t;
495 }
496 
497 static time_t
498 hunt(char *name, time_t lot, time_t hit)
499 {
500 	time_t			t;
501 	long			diff;
502 	struct tm		lotm;
503 	struct tm *	lotmp;
504 	struct tm		tm;
505 	struct tm *	tmp;
506 	char			loab[MAX_STRING_LENGTH];
507 
508 	lotmp = my_localtime(&lot);
509 	if (lotmp != NULL) {
510 		lotm = *lotmp;
511 		(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
512 	}
513 	for ( ; ; ) {
514 		diff = (long) (hit - lot);
515 		if (diff < 2)
516 			break;
517 		t = lot;
518 		t += diff / 2;
519 		if (t <= lot)
520 			++t;
521 		else if (t >= hit)
522 			--t;
523 		tmp = my_localtime(&t);
524 		if (tmp != NULL)
525 			tm = *tmp;
526 		if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
527 			(delta(&tm, &lotm) == (t - lot) &&
528 			tm.tm_isdst == lotm.tm_isdst &&
529 			strcmp(abbr(&tm), loab) == 0)) {
530 				lot = t;
531 				lotm = tm;
532 				lotmp = tmp;
533 		} else	hit = t;
534 	}
535 	show(name, lot, TRUE);
536 	show(name, hit, TRUE);
537 	return hit;
538 }
539 
540 /*
541 ** Thanks to Paul Eggert for logic used in delta.
542 */
543 
544 static long
545 delta(struct tm *newp, struct tm *oldp)
546 {
547 	long	result;
548 	int	tmy;
549 
550 	if (newp->tm_year < oldp->tm_year)
551 		return -delta(oldp, newp);
552 	result = 0;
553 	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
554 		result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
555 	result += newp->tm_yday - oldp->tm_yday;
556 	result *= HOURSPERDAY;
557 	result += newp->tm_hour - oldp->tm_hour;
558 	result *= MINSPERHOUR;
559 	result += newp->tm_min - oldp->tm_min;
560 	result *= SECSPERMIN;
561 	result += newp->tm_sec - oldp->tm_sec;
562 	return result;
563 }
564 
565 static void
566 show(char *zone, time_t t, int v)
567 {
568 	struct tm *	tmp;
569 
570 	(void) printf("%-*s  ", (int) longest, zone);
571 	if (v) {
572 		tmp = gmtime(&t);
573 		if (tmp == NULL) {
574 			(void) printf(tformat(), t);
575 		} else {
576 			dumptime(tmp);
577 			(void) printf(" UTC");
578 		}
579 		(void) printf(" = ");
580 	}
581 	tmp = my_localtime(&t);
582 	dumptime(tmp);
583 	if (tmp != NULL) {
584 		if (*abbr(tmp) != '\0')
585 			(void) printf(" %s", abbr(tmp));
586 		if (v) {
587 			(void) printf(" isdst=%d", tmp->tm_isdst);
588 #ifdef TM_GMTOFF
589 			(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
590 #endif /* defined TM_GMTOFF */
591 		}
592 	}
593 	(void) printf("\n");
594 	if (tmp != NULL && *abbr(tmp) != '\0')
595 		abbrok(abbr(tmp), zone);
596 }
597 
598 static const char *
599 abbr(struct tm *tmp)
600 {
601 	const char *	result;
602 	static const char	nada;
603 
604 	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
605 		return &nada;
606 	result = tzname[tmp->tm_isdst];
607 	return (result == NULL) ? &nada : result;
608 }
609 
610 /*
611 ** The code below can fail on certain theoretical systems;
612 ** it works on all known real-world systems as of 2004-12-30.
613 */
614 
615 static const char *
616 tformat(void)
617 {
618 	if (0.5 == (time_t) 0.5) {	/* floating */
619 		if (sizeof (time_t) > sizeof (double))
620 			return "%Lg";
621 		return "%g";
622 	}
623 	if (0 > (time_t) -1) {		/* signed */
624 		if (sizeof (time_t) > sizeof (long))
625 			return "%lld";
626 		if (sizeof (time_t) > sizeof (int))
627 			return "%ld";
628 		return "%d";
629 	}
630 	if (sizeof (time_t) > sizeof (unsigned long))
631 		return "%llu";
632 	if (sizeof (time_t) > sizeof (unsigned int))
633 		return "%lu";
634 	return "%u";
635 }
636 
637 static void
638 dumptime(const struct tm *timeptr)
639 {
640 	static const char	wday_name[][3] = {
641 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
642 	};
643 	static const char	mon_name[][3] = {
644 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
645 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
646 	};
647 	const char *	wn;
648 	const char *	mn;
649 	int		lead;
650 	int		trail;
651 
652 	if (timeptr == NULL) {
653 		(void) printf("NULL");
654 		return;
655 	}
656 	/*
657 	** The packaged versions of localtime and gmtime never put out-of-range
658 	** values in tm_wday or tm_mon, but since this code might be compiled
659 	** with other (perhaps experimental) versions, paranoia is in order.
660 	*/
661 	if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
662 		(int) (sizeof wday_name / sizeof wday_name[0]))
663 			wn = "???";
664 	else		wn = wday_name[timeptr->tm_wday];
665 	if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
666 		(int) (sizeof mon_name / sizeof mon_name[0]))
667 			mn = "???";
668 	else		mn = mon_name[timeptr->tm_mon];
669 	(void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
670 		wn, mn,
671 		timeptr->tm_mday, timeptr->tm_hour,
672 		timeptr->tm_min, timeptr->tm_sec);
673 #define DIVISOR	10
674 	trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
675 	lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
676 		trail / DIVISOR;
677 	trail %= DIVISOR;
678 	if (trail < 0 && lead > 0) {
679 		trail += DIVISOR;
680 		--lead;
681 	} else if (lead < 0 && trail > 0) {
682 		trail -= DIVISOR;
683 		++lead;
684 	}
685 	if (lead == 0)
686 		(void) printf("%d", trail);
687 	else	(void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
688 }
689