xref: /netbsd-src/lib/libc/time/zdump.c (revision 7788a0781fe6ff2cce37368b4578a7ade0850cb1)
1 /*	$NetBSD: zdump.c,v 1.30 2013/07/17 23:09:26 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 1.30 2013/07/17 23:09:26 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 "float.h"	/* for FLT_MAX and DBL_MAX */
31 #include "ctype.h"	/* for isalpha et al. */
32 #ifndef isascii
33 #define isascii(x) 1
34 #endif /* !defined isascii */
35 
36 /*
37 ** Substitutes for pre-C99 compilers.
38 ** Much of this section of code is stolen from private.h.
39 */
40 
41 #ifndef HAVE_STDINT_H
42 # define HAVE_STDINT_H \
43     (199901 <= __STDC_VERSION__ || 2 < (__GLIBC__ + (0 < __GLIBC_MINOR__)))
44 #endif
45 #if HAVE_STDINT_H
46 # include "stdint.h"
47 #endif
48 #ifndef HAVE_INTTYPES_H
49 # define HAVE_INTTYPES_H HAVE_STDINT_H
50 #endif
51 #if HAVE_INTTYPES_H
52 # include <inttypes.h>
53 #endif
54 
55 #ifndef INT_FAST32_MAX
56 # if INT_MAX >> 31 == 0
57 typedef long int_fast32_t;
58 # else
59 typedef int int_fast32_t;
60 # endif
61 #endif
62 
63 #ifndef INTMAX_MAX
64 # if defined LLONG_MAX || defined __LONG_LONG_MAX__
65 typedef long long intmax_t;
66 #  define PRIdMAX "lld"
67 # else
68 typedef long intmax_t;
69 #  define PRIdMAX "ld"
70 # endif
71 #endif
72 #ifndef SCNdMAX
73 # define SCNdMAX PRIdMAX
74 #endif
75 
76 
77 #ifndef ZDUMP_LO_YEAR
78 #define ZDUMP_LO_YEAR	(-500)
79 #endif /* !defined ZDUMP_LO_YEAR */
80 
81 #ifndef ZDUMP_HI_YEAR
82 #define ZDUMP_HI_YEAR	2500
83 #endif /* !defined ZDUMP_HI_YEAR */
84 
85 #ifndef MAX_STRING_LENGTH
86 #define MAX_STRING_LENGTH	1024
87 #endif /* !defined MAX_STRING_LENGTH */
88 
89 #ifndef TRUE
90 #define TRUE		1
91 #endif /* !defined TRUE */
92 
93 #ifndef FALSE
94 #define FALSE		0
95 #endif /* !defined FALSE */
96 
97 #ifndef EXIT_SUCCESS
98 #define EXIT_SUCCESS	0
99 #endif /* !defined EXIT_SUCCESS */
100 
101 #ifndef EXIT_FAILURE
102 #define EXIT_FAILURE	1
103 #endif /* !defined EXIT_FAILURE */
104 
105 #ifndef SECSPERMIN
106 #define SECSPERMIN	60
107 #endif /* !defined SECSPERMIN */
108 
109 #ifndef MINSPERHOUR
110 #define MINSPERHOUR	60
111 #endif /* !defined MINSPERHOUR */
112 
113 #ifndef SECSPERHOUR
114 #define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
115 #endif /* !defined SECSPERHOUR */
116 
117 #ifndef HOURSPERDAY
118 #define HOURSPERDAY	24
119 #endif /* !defined HOURSPERDAY */
120 
121 #ifndef EPOCH_YEAR
122 #define EPOCH_YEAR	1970
123 #endif /* !defined EPOCH_YEAR */
124 
125 #ifndef TM_YEAR_BASE
126 #define TM_YEAR_BASE	1900
127 #endif /* !defined TM_YEAR_BASE */
128 
129 #ifndef DAYSPERNYEAR
130 #define DAYSPERNYEAR	365
131 #endif /* !defined DAYSPERNYEAR */
132 
133 #ifndef isleap
134 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
135 #endif /* !defined isleap */
136 
137 #ifndef isleap_sum
138 /*
139 ** See tzfile.h for details on isleap_sum.
140 */
141 #define isleap_sum(a, b)	isleap((a) % 400 + (b) % 400)
142 #endif /* !defined isleap_sum */
143 
144 #define SECSPERDAY	((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
145 #define SECSPERNYEAR	(SECSPERDAY * DAYSPERNYEAR)
146 #define SECSPERLYEAR	(SECSPERNYEAR + SECSPERDAY)
147 
148 #ifndef HAVE_GETTEXT
149 #define HAVE_GETTEXT 0
150 #endif
151 #if HAVE_GETTEXT
152 #include "locale.h"	/* for setlocale */
153 #include "libintl.h"
154 #endif /* HAVE_GETTEXT */
155 
156 #ifndef GNUC_or_lint
157 #ifdef lint
158 #define GNUC_or_lint
159 #else /* !defined lint */
160 #ifdef __GNUC__
161 #define GNUC_or_lint
162 #endif /* defined __GNUC__ */
163 #endif /* !defined lint */
164 #endif /* !defined GNUC_or_lint */
165 
166 #ifndef ATTRIBUTE_PURE
167 #if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
168 # define ATTRIBUTE_PURE __attribute__ ((ATTRIBUTE_PURE__))
169 #else
170 # define ATTRIBUTE_PURE /* empty */
171 #endif
172 #endif
173 
174 #ifndef INITIALIZE
175 #ifdef GNUC_or_lint
176 #define INITIALIZE(x)	((x) = 0)
177 #else /* !defined GNUC_or_lint */
178 #define INITIALIZE(x)
179 #endif /* !defined GNUC_or_lint */
180 #endif /* !defined INITIALIZE */
181 
182 /*
183 ** For the benefit of GNU folk...
184 ** `_(MSGID)' uses the current locale's message library string for MSGID.
185 ** The default is to use gettext if available, and use MSGID otherwise.
186 */
187 
188 #ifndef _
189 #if HAVE_GETTEXT
190 #define _(msgid) gettext(msgid)
191 #else /* !HAVE_GETTEXT */
192 #define _(msgid) msgid
193 #endif /* !HAVE_GETTEXT */
194 #endif /* !defined _ */
195 
196 #ifndef TZ_DOMAIN
197 #define TZ_DOMAIN "tz"
198 #endif /* !defined TZ_DOMAIN */
199 
200 extern char **	environ;
201 extern int	getopt(int argc, char * const argv[],
202 			const char * options);
203 extern char *	optarg;
204 extern int	optind;
205 
206 /* The minimum and maximum finite time values.  */
207 static time_t	absolute_min_time =
208    ((time_t) 0.5 == 0.5
209     ? (sizeof (time_t) == sizeof (float) ? (time_t) -FLT_MAX
210        : sizeof (time_t) == sizeof (double) ? (time_t) -DBL_MAX
211        : sizeof (time_t) == sizeof (long double) ? (time_t) -LDBL_MAX
212        : 0)
213 #ifndef TIME_T_FLOATING
214     : (time_t) -1 < 0
215     ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
216 #endif
217     : 0);
218 static time_t	absolute_max_time =
219   ((time_t) 0.5 == 0.5
220    ? (sizeof (time_t) == sizeof (float) ? (time_t) FLT_MAX
221       : sizeof (time_t) == sizeof (double) ? (time_t) DBL_MAX
222       : sizeof (time_t) == sizeof (long double) ? (time_t) LDBL_MAX
223       : -1)
224 #ifndef TIME_T_FLOATING
225    : (time_t) -1 < 0
226    ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
227 #endif
228    : -1);
229 static size_t	longest;
230 static char *	progname;
231 static int	warned;
232 
233 static const char *	abbr(struct tm * tmp);
234 static void	abbrok(const char * abbrp, const char * zone);
235 static intmax_t	delta(struct tm * newp, struct tm * oldp) ATTRIBUTE_PURE;
236 static void	dumptime(const struct tm * tmp);
237 static time_t	hunt(char * name, time_t lot, time_t	hit);
238 static void	checkabsolutes(void);
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 >= 1 || *tp - t >= 1) {
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		dummy;
383 		intmax_t cutloyear = ZDUMP_LO_YEAR;
384 		intmax_t cuthiyear = ZDUMP_HI_YEAR;
385 		if (cutarg != NULL) {
386 			if (sscanf(cutarg, "%"SCNdMAX"%c", &hi, &dummy) == 1) {
387 				cuthiyear = hi;
388 			} else if (sscanf(cutarg, "%"SCNdMAX",%"SCNdMAX"%c",
389 				&lo, &hi, &dummy) == 2) {
390 					cutloyear = lo;
391 					cuthiyear = hi;
392 			} else {
393 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
394 					progname, cutarg);
395 				exit(EXIT_FAILURE);
396 			}
397 		}
398 		checkabsolutes();
399 		if (cutarg != NULL || cuttimes == NULL) {
400 			cutlotime = yeartot(cutloyear);
401 			cuthitime = yeartot(cuthiyear);
402 		}
403 		if (cuttimes != NULL) {
404 			if (sscanf(cuttimes, "%"SCNdMAX"%c", &hi, &dummy) == 1) {
405 				if (hi < cuthitime) {
406 					if (hi < absolute_min_time)
407 						hi = absolute_min_time;
408 					cuthitime = hi;
409 				}
410 			} else if (sscanf(cuttimes, "%"SCNdMAX",%"SCNdMAX"%c",
411 					  &lo, &hi, &dummy) == 2) {
412 				if (cutlotime < lo) {
413 					if (absolute_max_time < lo)
414 						lo = absolute_max_time;
415 					cutlotime = lo;
416 				}
417 				if (hi < cuthitime) {
418 					if (hi < absolute_min_time)
419 						hi = absolute_min_time;
420 					cuthitime = hi;
421 				}
422 			} else {
423 				(void) fprintf(stderr,
424 					_("%s: wild -t argument %s\n"),
425 					progname, cuttimes);
426 				exit(EXIT_FAILURE);
427 			}
428 		}
429 	}
430 	(void) time(&now);
431 	longest = 0;
432 	for (i = optind; i < argc; ++i)
433 		if (strlen(argv[i]) > longest)
434 			longest = strlen(argv[i]);
435 	{
436 		int	from;
437 		int	to;
438 
439 		for (i = 0; environ[i] != NULL; ++i)
440 			continue;
441 		fakeenv = malloc((i + 2) * sizeof *fakeenv);
442 		if (fakeenv == NULL ||
443 			(fakeenv[0] = malloc(longest + 4)) == NULL) {
444 			err(EXIT_FAILURE, "Can't allocated %zu bytes",
445 			    longest + 4);
446 		}
447 		to = 0;
448 		(void)strcpy(fakeenv[to++], "TZ=");	/* XXX strcpy is safe */
449 		for (from = 0; environ[from] != NULL; ++from)
450 			if (strncmp(environ[from], "TZ=", 3) != 0)
451 				fakeenv[to++] = environ[from];
452 		fakeenv[to] = NULL;
453 		environ = fakeenv;
454 	}
455 	for (i = optind; i < argc; ++i) {
456 		static char	buf[MAX_STRING_LENGTH];
457 
458 		(void) strcpy(&fakeenv[0][3], argv[i]);	/* XXX strcpy is safe */
459 		if (! (vflag | Vflag)) {
460 			show(argv[i], now, FALSE);
461 			continue;
462 		}
463 		warned = FALSE;
464 		t = absolute_min_time;
465 		if (!Vflag) {
466 			show(argv[i], t, TRUE);
467 			t += SECSPERHOUR * HOURSPERDAY;
468 			show(argv[i], t, TRUE);
469 		}
470 		if (t < cutlotime)
471 			t = cutlotime;
472 		tmp = my_localtime(&t);
473 		if (tmp != NULL) {
474 			tm = *tmp;
475 			(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
476 		}
477 		for ( ; ; ) {
478 			if (t >= cuthitime || t >= cuthitime - SECSPERHOUR * 12)
479 				break;
480 			newt = t + SECSPERHOUR * 12;
481 			newtmp = localtime(&newt);
482 			if (newtmp != NULL)
483 				newtm = *newtmp;
484 			if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
485 				(delta(&newtm, &tm) != (newt - t) ||
486 				newtm.tm_isdst != tm.tm_isdst ||
487 				strcmp(abbr(&newtm), buf) != 0)) {
488 					newt = hunt(argv[i], t, newt);
489 					newtmp = localtime(&newt);
490 					if (newtmp != NULL) {
491 						newtm = *newtmp;
492 						(void) strncpy(buf,
493 							abbr(&newtm),
494 							(sizeof buf) - 1);
495 					}
496 			}
497 			t = newt;
498 			tm = newtm;
499 			tmp = newtmp;
500 		}
501 		if (!Vflag) {
502 			t = absolute_max_time;
503 			t -= SECSPERHOUR * HOURSPERDAY;
504 			show(argv[i], t, TRUE);
505 			t += SECSPERHOUR * HOURSPERDAY;
506 			show(argv[i], t, TRUE);
507 		}
508 	}
509 	if (fflush(stdout) || ferror(stdout)) {
510 		err(EXIT_FAILURE, _("Error writing standard output"));
511 	}
512 	exit(EXIT_SUCCESS);
513 	/* If exit fails to exit... */
514 	return EXIT_FAILURE;
515 }
516 
517 static void
518 checkabsolutes(void)
519 {
520 	if (absolute_max_time < absolute_min_time) {
521 		(void) fprintf(stderr,
522 _("%s: use of -v on system with floating time_t other than float or double\n"),
523 			       progname);
524 		exit(EXIT_FAILURE);
525 	}
526 }
527 
528 static time_t
529 yeartot(const long y)
530 {
531 	intmax_t	myy;
532 	int_fast32_t	seconds;
533 	time_t		t;
534 
535 	myy = EPOCH_YEAR;
536 	t = 0;
537 	while (myy != y) {
538 		if (myy < y) {
539 			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
540 			++myy;
541 			if (t > absolute_max_time - seconds) {
542 				t = absolute_max_time;
543 				break;
544 			}
545 			t += seconds;
546 		} else {
547 			--myy;
548 			seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
549 			if (t < absolute_min_time + seconds) {
550 				t = absolute_min_time;
551 				break;
552 			}
553 			t -= seconds;
554 		}
555 	}
556 	return t;
557 }
558 
559 static time_t
560 hunt(char *name, time_t lot, time_t hit)
561 {
562 	time_t			t;
563 	struct tm		lotm;
564 	struct tm *	lotmp;
565 	struct tm		tm;
566 	struct tm *	tmp;
567 	char			loab[MAX_STRING_LENGTH];
568 
569 	lotmp = my_localtime(&lot);
570 	if (lotmp != NULL) {
571 		lotm = *lotmp;
572 		(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
573 	}
574 	for ( ; ; ) {
575 		time_t diff = hit - lot;
576 		if (diff < 2)
577 			break;
578 		t = lot;
579 		t += diff / 2;
580 		if (t <= lot)
581 			++t;
582 		else if (t >= hit)
583 			--t;
584 		tmp = my_localtime(&t);
585 		if (tmp != NULL)
586 			tm = *tmp;
587 		if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
588 			(delta(&tm, &lotm) == (t - lot) &&
589 			tm.tm_isdst == lotm.tm_isdst &&
590 			strcmp(abbr(&tm), loab) == 0)) {
591 				lot = t;
592 				lotm = tm;
593 				lotmp = tmp;
594 		} else	hit = t;
595 	}
596 	show(name, lot, TRUE);
597 	show(name, hit, TRUE);
598 	return hit;
599 }
600 
601 /*
602 ** Thanks to Paul Eggert for logic used in delta.
603 */
604 
605 static intmax_t
606 delta(struct tm *newp, struct tm *oldp)
607 {
608 	intmax_t	result;
609 	int		tmy;
610 
611 	if (newp->tm_year < oldp->tm_year)
612 		return -delta(oldp, newp);
613 	result = 0;
614 	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
615 		result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
616 	result += newp->tm_yday - oldp->tm_yday;
617 	result *= HOURSPERDAY;
618 	result += newp->tm_hour - oldp->tm_hour;
619 	result *= MINSPERHOUR;
620 	result += newp->tm_min - oldp->tm_min;
621 	result *= SECSPERMIN;
622 	result += newp->tm_sec - oldp->tm_sec;
623 	return result;
624 }
625 
626 static void
627 show(char *zone, time_t t, int v)
628 {
629 	struct tm *	tmp;
630 
631 	(void) printf("%-*s  ", (int) longest, zone);
632 	if (v) {
633 		tmp = gmtime(&t);
634 		if (tmp == NULL) {
635 			(void) printf(tformat(), t);
636 		} else {
637 			dumptime(tmp);
638 			(void) printf(" UTC");
639 		}
640 		(void) printf(" = ");
641 	}
642 	tmp = my_localtime(&t);
643 	dumptime(tmp);
644 	if (tmp != NULL) {
645 		if (*abbr(tmp) != '\0')
646 			(void) printf(" %s", abbr(tmp));
647 		if (v) {
648 			(void) printf(" isdst=%d", tmp->tm_isdst);
649 #ifdef TM_GMTOFF
650 			(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
651 #endif /* defined TM_GMTOFF */
652 		}
653 	}
654 	(void) printf("\n");
655 	if (tmp != NULL && *abbr(tmp) != '\0')
656 		abbrok(abbr(tmp), zone);
657 }
658 
659 static const char *
660 abbr(struct tm *tmp)
661 {
662 	const char *	result;
663 	static const char	nada;
664 
665 	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
666 		return &nada;
667 	result = tzname[tmp->tm_isdst];
668 	return (result == NULL) ? &nada : result;
669 }
670 
671 /*
672 ** The code below can fail on certain theoretical systems;
673 ** it works on all known real-world systems as of 2004-12-30.
674 */
675 
676 static const char *
677 tformat(void)
678 {
679 	if (0.5 == (time_t) 0.5) {	/* floating */
680 		if (sizeof (time_t) > sizeof (double))
681 			return "%Lg";
682 		return "%g";
683 	}
684 	if (0 > (time_t) -1) {		/* signed */
685 		if (sizeof (time_t) == sizeof (intmax_t))
686 			return "%"PRIdMAX;
687 		if (sizeof (time_t) > sizeof (long))
688 			return "%lld";
689 		if (sizeof (time_t) > sizeof (int))
690 			return "%ld";
691 		return "%d";
692 	}
693 #ifdef PRIuMAX
694 	if (sizeof (time_t) == sizeof (uintmax_t))
695 		return "%"PRIuMAX;
696 #endif
697 	if (sizeof (time_t) > sizeof (unsigned long))
698 		return "%llu";
699 	if (sizeof (time_t) > sizeof (unsigned int))
700 		return "%lu";
701 	return "%u";
702 }
703 
704 static void
705 dumptime(const struct tm *timeptr)
706 {
707 	static const char	wday_name[][3] = {
708 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
709 	};
710 	static const char	mon_name[][3] = {
711 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
712 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
713 	};
714 	const char *	wn;
715 	const char *	mn;
716 	int		lead;
717 	int		trail;
718 
719 	if (timeptr == NULL) {
720 		(void) printf("NULL");
721 		return;
722 	}
723 	/*
724 	** The packaged versions of localtime and gmtime never put out-of-range
725 	** values in tm_wday or tm_mon, but since this code might be compiled
726 	** with other (perhaps experimental) versions, paranoia is in order.
727 	*/
728 	if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
729 		(int) (sizeof wday_name / sizeof wday_name[0]))
730 			wn = "???";
731 	else		wn = wday_name[timeptr->tm_wday];
732 	if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
733 		(int) (sizeof mon_name / sizeof mon_name[0]))
734 			mn = "???";
735 	else		mn = mon_name[timeptr->tm_mon];
736 	(void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
737 		wn, mn,
738 		timeptr->tm_mday, timeptr->tm_hour,
739 		timeptr->tm_min, timeptr->tm_sec);
740 #define DIVISOR	10
741 	trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
742 	lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
743 		trail / DIVISOR;
744 	trail %= DIVISOR;
745 	if (trail < 0 && lead > 0) {
746 		trail += DIVISOR;
747 		--lead;
748 	} else if (lead < 0 && trail > 0) {
749 		trail -= DIVISOR;
750 		++lead;
751 	}
752 	if (lead == 0)
753 		(void) printf("%d", trail);
754 	else	(void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
755 }
756