xref: /netbsd-src/lib/libc/time/zdump.c (revision 6a493d6bc668897c91594964a732d38505b70cbb)
1 /*	$NetBSD: zdump.c,v 1.32 2013/12/26 18:34:28 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 1.32 2013/12/26 18:34:28 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 ** However, include private.h when debugging, so that it overrides
19 ** time_t consistently with the rest of the package.
20 */
21 
22 #include "private.h"
23 
24 #include "stdio.h"	/* for stdout, stderr */
25 #include "string.h"	/* for strcpy */
26 #include "sys/types.h"	/* for time_t */
27 #include "time.h"	/* for struct tm */
28 #include "stdlib.h"	/* for exit, malloc, atoi */
29 #include <err.h>
30 #include "ctype.h"	/* for isalpha et al. */
31 #ifndef isascii
32 #define isascii(x) 1
33 #endif /* !defined isascii */
34 
35 /*
36 ** Substitutes for pre-C99 compilers.
37 ** Much of this section of code is stolen from private.h.
38 */
39 
40 #ifndef HAVE_STDINT_H
41 # define HAVE_STDINT_H \
42     (199901 <= __STDC_VERSION__ || 2 < (__GLIBC__ + (0 < __GLIBC_MINOR__)))
43 #endif
44 #if HAVE_STDINT_H
45 # include "stdint.h"
46 #endif
47 #ifndef HAVE_INTTYPES_H
48 # define HAVE_INTTYPES_H HAVE_STDINT_H
49 #endif
50 #if HAVE_INTTYPES_H
51 # include <inttypes.h>
52 #endif
53 
54 #ifndef INT_FAST32_MAX
55 # if INT_MAX >> 31 == 0
56 typedef long int_fast32_t;
57 # else
58 typedef int int_fast32_t;
59 # endif
60 #endif
61 
62 #ifndef INTMAX_MAX
63 # if defined LLONG_MAX || defined __LONG_LONG_MAX__
64 typedef long long intmax_t;
65 #  define strtoimax strtoll
66 #  define PRIdMAX "lld"
67 #  ifdef LLONG_MAX
68 #   define INTMAX_MAX LLONG_MAX
69 #  else
70 #   define INTMAX_MAX __LONG_LONG_MAX__
71 #  endif
72 # else
73 typedef long intmax_t;
74 #  define strtoimax strtol
75 #  define PRIdMAX "ld"
76 #  define INTMAX_MAX LONG_MAX
77 # endif
78 #endif
79 
80 
81 #ifndef ZDUMP_LO_YEAR
82 #define ZDUMP_LO_YEAR	(-500)
83 #endif /* !defined ZDUMP_LO_YEAR */
84 
85 #ifndef ZDUMP_HI_YEAR
86 #define ZDUMP_HI_YEAR	2500
87 #endif /* !defined ZDUMP_HI_YEAR */
88 
89 #ifndef MAX_STRING_LENGTH
90 #define MAX_STRING_LENGTH	1024
91 #endif /* !defined MAX_STRING_LENGTH */
92 
93 #ifndef TRUE
94 #define TRUE		1
95 #endif /* !defined TRUE */
96 
97 #ifndef FALSE
98 #define FALSE		0
99 #endif /* !defined FALSE */
100 
101 #ifndef EXIT_SUCCESS
102 #define EXIT_SUCCESS	0
103 #endif /* !defined EXIT_SUCCESS */
104 
105 #ifndef EXIT_FAILURE
106 #define EXIT_FAILURE	1
107 #endif /* !defined EXIT_FAILURE */
108 
109 #ifndef SECSPERMIN
110 #define SECSPERMIN	60
111 #endif /* !defined SECSPERMIN */
112 
113 #ifndef MINSPERHOUR
114 #define MINSPERHOUR	60
115 #endif /* !defined MINSPERHOUR */
116 
117 #ifndef SECSPERHOUR
118 #define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
119 #endif /* !defined SECSPERHOUR */
120 
121 #ifndef HOURSPERDAY
122 #define HOURSPERDAY	24
123 #endif /* !defined HOURSPERDAY */
124 
125 #ifndef EPOCH_YEAR
126 #define EPOCH_YEAR	1970
127 #endif /* !defined EPOCH_YEAR */
128 
129 #ifndef TM_YEAR_BASE
130 #define TM_YEAR_BASE	1900
131 #endif /* !defined TM_YEAR_BASE */
132 
133 #ifndef DAYSPERNYEAR
134 #define DAYSPERNYEAR	365
135 #endif /* !defined DAYSPERNYEAR */
136 
137 #ifndef isleap
138 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
139 #endif /* !defined isleap */
140 
141 #ifndef isleap_sum
142 /*
143 ** See tzfile.h for details on isleap_sum.
144 */
145 #define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
146 #endif /* !defined isleap_sum */
147 
148 #define SECSPERDAY	((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
149 #define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
150 #define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
151 #define SECSPER400YEARS	(SECSPERNYEAR * (intmax_t) (300 + 3)	\
152 			 + SECSPERLYEAR * (intmax_t) (100 - 3))
153 
154 /*
155 ** True if SECSPER400YEARS is known to be representable as an
156 ** intmax_t.  It's OK that SECSPER400YEARS_FITS can in theory be false
157 ** even if SECSPER400YEARS is representable, because when that happens
158 ** the code merely runs a bit more slowly, and this slowness doesn't
159 ** occur on any practical platform.
160 */
161 enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
162 
163 #ifndef HAVE_GETTEXT
164 #define HAVE_GETTEXT 0
165 #endif
166 #if HAVE_GETTEXT
167 #include "locale.h"	/* for setlocale */
168 #include "libintl.h"
169 #endif /* HAVE_GETTEXT */
170 
171 #ifndef GNUC_or_lint
172 #ifdef lint
173 #define GNUC_or_lint
174 #else /* !defined lint */
175 #ifdef __GNUC__
176 #define GNUC_or_lint
177 #endif /* defined __GNUC__ */
178 #endif /* !defined lint */
179 #endif /* !defined GNUC_or_lint */
180 
181 #ifndef ATTRIBUTE_PURE
182 #if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
183 # define ATTRIBUTE_PURE __attribute__ ((ATTRIBUTE_PURE__))
184 #else
185 # define ATTRIBUTE_PURE /* empty */
186 #endif
187 #endif
188 
189 #ifndef INITIALIZE
190 #ifdef GNUC_or_lint
191 #define INITIALIZE(x)	((x) = 0)
192 #else /* !defined GNUC_or_lint */
193 #define INITIALIZE(x)
194 #endif /* !defined GNUC_or_lint */
195 #endif /* !defined INITIALIZE */
196 
197 /*
198 ** For the benefit of GNU folk...
199 ** `_(MSGID)' uses the current locale's message library string for MSGID.
200 ** The default is to use gettext if available, and use MSGID otherwise.
201 */
202 
203 #ifndef _
204 #if HAVE_GETTEXT
205 #define _(msgid) gettext(msgid)
206 #else /* !HAVE_GETTEXT */
207 #define _(msgid) msgid
208 #endif /* !HAVE_GETTEXT */
209 #endif /* !defined _ */
210 
211 #ifndef TZ_DOMAIN
212 #define TZ_DOMAIN "tz"
213 #endif /* !defined TZ_DOMAIN */
214 
215 extern char **	environ;
216 extern int	getopt(int argc, char * const argv[],
217 			const char * options);
218 extern char *	optarg;
219 extern int	optind;
220 
221 /* The minimum and maximum finite time values.  */
222 static time_t	absolute_min_time =
223   ((time_t) -1 < 0
224     ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
225     : 0);
226 static time_t	absolute_max_time =
227   ((time_t) -1 < 0
228     ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
229    : -1);
230 static size_t	longest;
231 static char *	progname;
232 static int	warned;
233 
234 static const char *	abbr(struct tm * tmp);
235 static void	abbrok(const char * abbrp, const char * zone);
236 static intmax_t	delta(struct tm * newp, struct tm * oldp) ATTRIBUTE_PURE;
237 static void	dumptime(const struct tm * tmp);
238 static time_t	hunt(char * name, time_t lot, time_t	hit);
239 static void	show(char * zone, time_t t, int v);
240 static const char *	tformat(void);
241 static time_t	yeartot(long y) ATTRIBUTE_PURE;
242 
243 #ifndef TYPECHECK
244 #define my_localtime	localtime
245 #else /* !defined TYPECHECK */
246 static struct tm *
247 my_localtime(time_t *tp)
248 {
249 	struct tm *tmp;
250 
251 	tmp = localtime(tp);
252 	if (tp != NULL && tmp != NULL) {
253 		struct tm	tm;
254 		time_t	t;
255 
256 		tm = *tmp;
257 		t = mktime(&tm);
258 		if (t != *tp) {
259 			(void) fflush(stdout);
260 			(void) fprintf(stderr, "\n%s: ", progname);
261 			(void) fprintf(stderr, tformat(), *tp);
262 			(void) fprintf(stderr, " ->");
263 			(void) fprintf(stderr, " year=%d", tmp->tm_year);
264 			(void) fprintf(stderr, " mon=%d", tmp->tm_mon);
265 			(void) fprintf(stderr, " mday=%d", tmp->tm_mday);
266 			(void) fprintf(stderr, " hour=%d", tmp->tm_hour);
267 			(void) fprintf(stderr, " min=%d", tmp->tm_min);
268 			(void) fprintf(stderr, " sec=%d", tmp->tm_sec);
269 			(void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
270 			(void) fprintf(stderr, " -> ");
271 			(void) fprintf(stderr, tformat(), t);
272 			(void) fprintf(stderr, "\n");
273 		}
274 	}
275 	return tmp;
276 }
277 #endif /* !defined TYPECHECK */
278 
279 static void
280 abbrok(const char *const abbrp, const char *const zone)
281 {
282 	const char *cp;
283 	const char *wp;
284 
285 	if (warned)
286 		return;
287 	cp = abbrp;
288 	wp = NULL;
289 	while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
290 		++cp;
291 	if (cp - abbrp == 0)
292 		wp = _("lacks alphabetic at start");
293 	else if (cp - abbrp < 3)
294 		wp = _("has fewer than 3 alphabetics");
295 	else if (cp - abbrp > 6)
296 		wp = _("has more than 6 alphabetics");
297 	if (wp == NULL && (*cp == '+' || *cp == '-')) {
298 		++cp;
299 		if (isascii((unsigned char) *cp) &&
300 			isdigit((unsigned char) *cp))
301 				if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
302 					++cp;
303 		if (*cp != '\0')
304 			wp = _("differs from POSIX standard");
305 	}
306 	if (wp == NULL)
307 		return;
308 	(void) fflush(stdout);
309 	(void) fprintf(stderr,
310 		_("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
311 		progname, zone, abbrp, wp);
312 	warned = TRUE;
313 }
314 
315 __dead static void
316 usage(FILE *const stream, const int status)
317 {
318 	(void) fprintf(stream,
319 _("%s: usage: %s [--version] [--help] [-{vV}] [-{ct} [lo,]hi] zonename ...\n"
320   "\n"
321   "Report bugs to %s.\n"),
322 		       progname, progname, REPORT_BUGS_TO);
323 	exit(status);
324 }
325 
326 int
327 main(int argc, char *argv[])
328 {
329 	int		i;
330 	int		vflag;
331 	int		Vflag;
332 	char *		cutarg;
333 	char *		cuttimes;
334 	time_t		cutlotime;
335 	time_t		cuthitime;
336 	char **		fakeenv;
337 	time_t		now;
338 	time_t		t;
339 	time_t		newt;
340 	struct tm	tm;
341 	struct tm	newtm;
342 	struct tm *	tmp;
343 	struct tm *	newtmp;
344 
345 	cutlotime = absolute_min_time;
346 	cuthitime = absolute_max_time;
347 #if HAVE_GETTEXT
348 	(void) setlocale(LC_ALL, "");
349 #ifdef TZ_DOMAINDIR
350 	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
351 #endif /* defined TEXTDOMAINDIR */
352 	(void) textdomain(TZ_DOMAIN);
353 #endif /* HAVE_GETTEXT */
354 	progname = argv[0];
355 	for (i = 1; i < argc; ++i)
356 		if (strcmp(argv[i], "--version") == 0) {
357 			(void) printf("zdump %s%s\n", PKGVERSION, TZVERSION);
358 			exit(EXIT_SUCCESS);
359 		} else if (strcmp(argv[i], "--help") == 0) {
360 			usage(stdout, EXIT_SUCCESS);
361 		}
362 	vflag = Vflag = 0;
363 	cutarg = cuttimes = NULL;
364 	for (;;)
365 	  switch (getopt(argc, argv, "c:t:vV")) {
366 	  case 'c': cutarg = optarg; break;
367 	  case 't': cuttimes = optarg; break;
368 	  case 'v': vflag = 1; break;
369 	  case 'V': Vflag = 1; break;
370 	  case -1:
371 	    if (! (optind == argc - 1 && strcmp(argv[optind], "=") == 0))
372 	      goto arg_processing_done;
373 	    /* Fall through.  */
374 	  default:
375 	    usage(stderr, EXIT_FAILURE);
376 	  }
377  arg_processing_done:;
378 
379 	if (vflag | Vflag) {
380 		intmax_t	lo;
381 		intmax_t	hi;
382 		char *loend, *hiend;
383 		intmax_t cutloyear = ZDUMP_LO_YEAR;
384 		intmax_t cuthiyear = ZDUMP_HI_YEAR;
385 		if (cutarg != NULL) {
386 			lo = strtoimax(cutarg, &loend, 10);
387 			if (cutarg != loend && !*loend) {
388 				hi = lo;
389 				cuthiyear = hi;
390 			} else if (cutarg != loend && *loend == ','
391 				   && (hi = strtoimax(loend + 1, &hiend, 10),
392 				       loend + 1 != hiend && !*hiend)) {
393 				cutloyear = lo;
394 				cuthiyear = hi;
395 			} else {
396 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
397 					progname, cutarg);
398 				exit(EXIT_FAILURE);
399 			}
400 		}
401 		if (cutarg != NULL || cuttimes == NULL) {
402 			cutlotime = yeartot(cutloyear);
403 			cuthitime = yeartot(cuthiyear);
404 		}
405 		if (cuttimes != NULL) {
406 			lo = strtoimax(cuttimes, &loend, 10);
407 			if (cuttimes != loend && !*loend) {
408 				hi = lo;
409 				if (hi < cuthitime) {
410 					if (hi < absolute_min_time)
411 						hi = absolute_min_time;
412 					cuthitime = hi;
413 				}
414 			} else if (cuttimes != loend && *loend == ','
415 				   && (hi = strtoimax(loend + 1, &hiend, 10),
416 				       loend + 1 != hiend && !*hiend)) {
417 				if (cutlotime < lo) {
418 					if (absolute_max_time < lo)
419 						lo = absolute_max_time;
420 					cutlotime = lo;
421 				}
422 				if (hi < cuthitime) {
423 					if (hi < absolute_min_time)
424 						hi = absolute_min_time;
425 					cuthitime = hi;
426 				}
427 			} else {
428 				(void) fprintf(stderr,
429 					_("%s: wild -t argument %s\n"),
430 					progname, cuttimes);
431 				exit(EXIT_FAILURE);
432 			}
433 		}
434 	}
435 	(void) time(&now);
436 	longest = 0;
437 	for (i = optind; i < argc; ++i)
438 		if (strlen(argv[i]) > longest)
439 			longest = strlen(argv[i]);
440 	{
441 		int	from;
442 		int	to;
443 
444 		for (i = 0; environ[i] != NULL; ++i)
445 			continue;
446 		fakeenv = malloc((i + 2) * sizeof *fakeenv);
447 		if (fakeenv == NULL ||
448 			(fakeenv[0] = malloc(longest + 4)) == NULL) {
449 			err(EXIT_FAILURE, "Can't allocated %zu bytes",
450 			    longest + 4);
451 		}
452 		to = 0;
453 		(void)strcpy(fakeenv[to++], "TZ=");	/* XXX strcpy is safe */
454 		for (from = 0; environ[from] != NULL; ++from)
455 			if (strncmp(environ[from], "TZ=", 3) != 0)
456 				fakeenv[to++] = environ[from];
457 		fakeenv[to] = NULL;
458 		environ = fakeenv;
459 	}
460 	for (i = optind; i < argc; ++i) {
461 		static char	buf[MAX_STRING_LENGTH];
462 
463 		(void) strcpy(&fakeenv[0][3], argv[i]);	/* XXX strcpy is safe */
464 		if (! (vflag | Vflag)) {
465 			show(argv[i], now, FALSE);
466 			continue;
467 		}
468 		warned = FALSE;
469 		t = absolute_min_time;
470 		if (!Vflag) {
471 			show(argv[i], t, TRUE);
472 			t += SECSPERDAY;
473 			show(argv[i], t, TRUE);
474 		}
475 		if (t < cutlotime)
476 			t = cutlotime;
477 		tmp = my_localtime(&t);
478 		if (tmp != NULL) {
479 			tm = *tmp;
480 			(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
481 		}
482 		for ( ; ; ) {
483 			newt = (t < absolute_max_time - SECSPERDAY / 2
484 				? t + SECSPERDAY / 2
485 				: absolute_max_time);
486 			if (cuthitime <= newt)
487 				break;
488 			newtmp = localtime(&newt);
489 			if (newtmp != NULL)
490 				newtm = *newtmp;
491 			if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
492 				(delta(&newtm, &tm) != (newt - t) ||
493 				newtm.tm_isdst != tm.tm_isdst ||
494 				strcmp(abbr(&newtm), buf) != 0)) {
495 					newt = hunt(argv[i], t, newt);
496 					newtmp = localtime(&newt);
497 					if (newtmp != NULL) {
498 						newtm = *newtmp;
499 						(void) strncpy(buf,
500 							abbr(&newtm),
501 							(sizeof buf) - 1);
502 					}
503 			}
504 			t = newt;
505 			tm = newtm;
506 			tmp = newtmp;
507 		}
508 		if (!Vflag) {
509 			t = absolute_max_time;
510 			t -= SECSPERDAY;
511 			show(argv[i], t, TRUE);
512 			t += SECSPERDAY;
513 			show(argv[i], t, TRUE);
514 		}
515 	}
516 	if (fflush(stdout) || ferror(stdout)) {
517 		err(EXIT_FAILURE, _("Error writing standard output"));
518 	}
519 	exit(EXIT_SUCCESS);
520 	/* If exit fails to exit... */
521 	return EXIT_FAILURE;
522 }
523 
524 static time_t
525 yeartot(const long y)
526 {
527 	intmax_t	myy, seconds, years;
528 	time_t		t;
529 
530 	myy = EPOCH_YEAR;
531 	t = 0;
532 	while (myy < y) {
533 		if (SECSPER400YEARS_FITS && 400 <= y - myy) {
534 			intmax_t diff400 = (y - myy) / 400;
535 			if (INTMAX_MAX / SECSPER400YEARS < diff400)
536 				return absolute_max_time;
537 			seconds = diff400 * SECSPER400YEARS;
538 			years = diff400 * 400;
539                 } else {
540 			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
541 			years = 1;
542 		}
543 		myy += years;
544 		if (t > absolute_max_time - seconds)
545 			return absolute_max_time;
546 		t += seconds;
547 	}
548 	while (y < myy) {
549 		if (SECSPER400YEARS_FITS && y + 400 <= myy && myy < 0) {
550 			intmax_t diff400 = (myy - y) / 400;
551 			if (INTMAX_MAX / SECSPER400YEARS < diff400)
552 				return absolute_min_time;
553 			seconds = diff400 * SECSPER400YEARS;
554 			years = diff400 * 400;
555 		} else {
556 			seconds = isleap(myy - 1) ? SECSPERLYEAR : SECSPERNYEAR;
557 			years = 1;
558 		}
559 		myy -= years;
560 		if (t < absolute_min_time + seconds)
561 			return absolute_min_time;
562 		t -= seconds;
563 	}
564 	return t;
565 }
566 
567 static time_t
568 hunt(char *name, time_t lot, time_t hit)
569 {
570 	time_t			t;
571 	struct tm		lotm;
572 	struct tm *	lotmp;
573 	struct tm		tm;
574 	struct tm *	tmp;
575 	char			loab[MAX_STRING_LENGTH];
576 
577 	lotmp = my_localtime(&lot);
578 	if (lotmp != NULL) {
579 		lotm = *lotmp;
580 		(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
581 	}
582 	for ( ; ; ) {
583 		time_t diff = hit - lot;
584 		if (diff < 2)
585 			break;
586 		t = lot;
587 		t += diff / 2;
588 		if (t <= lot)
589 			++t;
590 		else if (t >= hit)
591 			--t;
592 		tmp = my_localtime(&t);
593 		if (tmp != NULL)
594 			tm = *tmp;
595 		if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
596 			(delta(&tm, &lotm) == (t - lot) &&
597 			tm.tm_isdst == lotm.tm_isdst &&
598 			strcmp(abbr(&tm), loab) == 0)) {
599 				lot = t;
600 				lotm = tm;
601 				lotmp = tmp;
602 		} else	hit = t;
603 	}
604 	show(name, lot, TRUE);
605 	show(name, hit, TRUE);
606 	return hit;
607 }
608 
609 /*
610 ** Thanks to Paul Eggert for logic used in delta.
611 */
612 
613 static intmax_t
614 delta(struct tm *newp, struct tm *oldp)
615 {
616 	intmax_t	result;
617 	int		tmy;
618 
619 	if (newp->tm_year < oldp->tm_year)
620 		return -delta(oldp, newp);
621 	result = 0;
622 	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
623 		result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
624 	result += newp->tm_yday - oldp->tm_yday;
625 	result *= HOURSPERDAY;
626 	result += newp->tm_hour - oldp->tm_hour;
627 	result *= MINSPERHOUR;
628 	result += newp->tm_min - oldp->tm_min;
629 	result *= SECSPERMIN;
630 	result += newp->tm_sec - oldp->tm_sec;
631 	return result;
632 }
633 
634 static void
635 show(char *zone, time_t t, int v)
636 {
637 	struct tm *	tmp;
638 
639 	(void) printf("%-*s  ", (int) longest, zone);
640 	if (v) {
641 		tmp = gmtime(&t);
642 		if (tmp == NULL) {
643 			(void) printf(tformat(), t);
644 		} else {
645 			dumptime(tmp);
646 			(void) printf(" UT");
647 		}
648 		(void) printf(" = ");
649 	}
650 	tmp = my_localtime(&t);
651 	dumptime(tmp);
652 	if (tmp != NULL) {
653 		if (*abbr(tmp) != '\0')
654 			(void) printf(" %s", abbr(tmp));
655 		if (v) {
656 			(void) printf(" isdst=%d", tmp->tm_isdst);
657 #ifdef TM_GMTOFF
658 			(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
659 #endif /* defined TM_GMTOFF */
660 		}
661 	}
662 	(void) printf("\n");
663 	if (tmp != NULL && *abbr(tmp) != '\0')
664 		abbrok(abbr(tmp), zone);
665 }
666 
667 static const char *
668 abbr(struct tm *tmp)
669 {
670 	const char *	result;
671 	static const char	nada;
672 
673 	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
674 		return &nada;
675 	result = tzname[tmp->tm_isdst];
676 	return (result == NULL) ? &nada : result;
677 }
678 
679 /*
680 ** The code below can fail on certain theoretical systems;
681 ** it works on all known real-world systems as of 2004-12-30.
682 */
683 
684 static const char *
685 tformat(void)
686 {
687 	if (0 > (time_t) -1) {		/* signed */
688 		if (sizeof (time_t) == sizeof (intmax_t))
689 			return "%"PRIdMAX;
690 		if (sizeof (time_t) > sizeof (long))
691 			return "%lld";
692 		if (sizeof (time_t) > sizeof (int))
693 			return "%ld";
694 		return "%d";
695 	}
696 #ifdef PRIuMAX
697 	if (sizeof (time_t) == sizeof (uintmax_t))
698 		return "%"PRIuMAX;
699 #endif
700 	if (sizeof (time_t) > sizeof (unsigned long))
701 		return "%llu";
702 	if (sizeof (time_t) > sizeof (unsigned int))
703 		return "%lu";
704 	return "%u";
705 }
706 
707 static void
708 dumptime(const struct tm *timeptr)
709 {
710 	static const char	wday_name[][3] = {
711 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
712 	};
713 	static const char	mon_name[][3] = {
714 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
715 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
716 	};
717 	const char *	wn;
718 	const char *	mn;
719 	int		lead;
720 	int		trail;
721 
722 	if (timeptr == NULL) {
723 		(void) printf("NULL");
724 		return;
725 	}
726 	/*
727 	** The packaged versions of localtime and gmtime never put out-of-range
728 	** values in tm_wday or tm_mon, but since this code might be compiled
729 	** with other (perhaps experimental) versions, paranoia is in order.
730 	*/
731 	if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
732 		(int) (sizeof wday_name / sizeof wday_name[0]))
733 			wn = "???";
734 	else		wn = wday_name[timeptr->tm_wday];
735 	if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
736 		(int) (sizeof mon_name / sizeof mon_name[0]))
737 			mn = "???";
738 	else		mn = mon_name[timeptr->tm_mon];
739 	(void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
740 		wn, mn,
741 		timeptr->tm_mday, timeptr->tm_hour,
742 		timeptr->tm_min, timeptr->tm_sec);
743 #define DIVISOR	10
744 	trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
745 	lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
746 		trail / DIVISOR;
747 	trail %= DIVISOR;
748 	if (trail < 0 && lead > 0) {
749 		trail += DIVISOR;
750 		--lead;
751 	} else if (lead < 0 && trail > 0) {
752 		trail -= DIVISOR;
753 		++lead;
754 	}
755 	if (lead == 0)
756 		(void) printf("%d", trail);
757 	else	(void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
758 }
759