[apple/system_cmds.git] / zdump.tproj / zdump.c

static const char	elsieid[] = "@(#)zdump.c	7.31";

#ifndef lint
#include <sys/cdefs.h>
__unused static const char rcsid[] =
  "$FreeBSD: src/usr.sbin/zic/zdump.c,v 1.10 2008/02/19 07:09:19 ru Exp $";
#endif /* not lint */

/*
** This code has been made independent of the rest of the time
** conversion package to increase confidence in the verification it provides.
** You can use this code to help in verifying other implementations.
*/

#include <err.h>
#include <stdio.h>	/* for stdout, stderr */
#include <stdlib.h>	/* for exit, malloc, atoi */
#include <string.h>	/* for strcpy */
#include <sys/types.h>	/* for time_t */
#include <time.h>	/* for struct tm */
#include <unistd.h>
#include <limits.h>

#ifndef MAX_STRING_LENGTH
#define MAX_STRING_LENGTH	1024
#endif /* !defined MAX_STRING_LENGTH */

#ifndef TRUE
#define TRUE		1
#endif /* !defined TRUE */

#ifndef FALSE
#define FALSE		0
#endif /* !defined FALSE */

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS	0
#endif /* !defined EXIT_SUCCESS */

#ifndef EXIT_FAILURE
#define EXIT_FAILURE	1
#endif /* !defined EXIT_FAILURE */

#ifndef SECSPERMIN
#define SECSPERMIN	60
#endif /* !defined SECSPERMIN */

#ifndef MINSPERHOUR
#define MINSPERHOUR	60
#endif /* !defined MINSPERHOUR */

#ifndef SECSPERHOUR
#define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
#endif /* !defined SECSPERHOUR */

#ifndef HOURSPERDAY
#define HOURSPERDAY	24
#endif /* !defined HOURSPERDAY */

#ifndef EPOCH_YEAR
#define EPOCH_YEAR	1970
#endif /* !defined EPOCH_YEAR */

#ifndef TM_YEAR_BASE
#define TM_YEAR_BASE	1900
#endif /* !defined TM_YEAR_BASE */

#ifndef DAYSPERNYEAR
#define DAYSPERNYEAR	365
#endif /* !defined DAYSPERNYEAR */

#ifndef isleap
#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
#endif /* !defined isleap */

#if HAVE_GETTEXT - 0
#include "locale.h"	/* for setlocale */
#include "libintl.h"
#endif /* HAVE_GETTEXT - 0 */

#ifndef GNUC_or_lint
#ifdef lint
#define GNUC_or_lint
#endif /* defined lint */
#ifndef lint
#ifdef __GNUC__
#define GNUC_or_lint
#endif /* defined __GNUC__ */
#endif /* !defined lint */
#endif /* !defined GNUC_or_lint */

#ifndef INITIALIZE
#ifdef GNUC_or_lint
#define INITIALIZE(x)	((x) = 0)
#endif /* defined GNUC_or_lint */
#ifndef GNUC_or_lint
#define INITIALIZE(x)
#endif /* !defined GNUC_or_lint */
#endif /* !defined INITIALIZE */

/*
** For the benefit of GNU folk...
** `_(MSGID)' uses the current locale's message library string for MSGID.
** The default is to use gettext if available, and use MSGID otherwise.
*/

#ifndef _
#if HAVE_GETTEXT - 0
#define _(msgid) gettext(msgid)
#else /* !(HAVE_GETTEXT - 0) */
#define _(msgid) msgid
#endif /* !(HAVE_GETTEXT - 0) */
#endif /* !defined _ */

#ifndef TZ_DOMAIN
#define TZ_DOMAIN "tz"
#endif /* !defined TZ_DOMAIN */

#ifndef P
#ifdef __STDC__
#define P(x)	x
#endif /* defined __STDC__ */
#ifndef __STDC__
#define P(x)	()
#endif /* !defined __STDC__ */
#endif /* !defined P */

extern char **	environ;
extern char *	tzname[2];

static char *	abbr P((struct tm * tmp));
static long	delta P((struct tm * newp, struct tm * oldp));
static time_t	hunt P((char * name, time_t lot, time_t	hit));
static size_t	longest;
static void	show P((char * zone, time_t t, int v));
static void     usage(void);

int
main(int argc, char *argv[])
{
	int			i;
	int			c;
	int			vflag;
	char *			cutoff;
	int			cutyear;
	long			cuttime;
	char **			fakeenv;
	time_t			now;
	time_t			t;
	time_t			newt;
#ifndef __APPLE__
// <rdar://problem/6013740>
// The approach of walking through every day from the minimum
// possible time_t value to the maximum possible time_t value
// falls apart with 64-bit time_t (takes too long to iterate,
// and causes gmtime(3) and localtime(3) to return EOVERFLOW
// which this code does not anticipate).  Limiting the time_t
// range to [INT_MIN:INT_MAX] even on LP64.
	time_t			hibit;
#endif
	struct tm		tm;
	struct tm		newtm;

	INITIALIZE(cuttime);
#if HAVE_GETTEXT - 0
	(void) setlocale(LC_MESSAGES, "");
#ifdef TZ_DOMAINDIR
	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
#endif /* defined(TEXTDOMAINDIR) */
	(void) textdomain(TZ_DOMAIN);
#endif /* HAVE_GETTEXT - 0 */
	for (i = 1; i < argc; ++i)
		if (strcmp(argv[i], "--version") == 0) {
			errx(EXIT_SUCCESS, "%s", elsieid);
		}
	vflag = 0;
	cutoff = NULL;
	while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
		if (c == 'v')
			vflag = 1;
		else	cutoff = optarg;
	if ((c != -1) ||
		(optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
			usage();
	}
	if (cutoff != NULL) {
		int	y;

		cutyear = atoi(cutoff);
		cuttime = 0;
		for (y = EPOCH_YEAR; y < cutyear; ++y)
			cuttime += DAYSPERNYEAR + isleap(y);
		cuttime *= SECSPERHOUR * HOURSPERDAY;
	}
	(void) time(&now);
	longest = 0;
	for (i = optind; i < argc; ++i)
		if (strlen(argv[i]) > longest)
			longest = strlen(argv[i]);
#ifndef __APPLE__
	for (hibit = 1; (hibit << 1) != 0; hibit <<= 1)
		continue;
#endif
	{
		int	from;
		int	to;

		for (i = 0;  environ[i] != NULL;  ++i)
			continue;
		fakeenv = (char **) malloc((size_t) ((i + 2) *
			sizeof *fakeenv));
		if (fakeenv == NULL ||
			(fakeenv[0] = (char *) malloc((size_t) (longest +
				4))) == NULL)
					errx(EXIT_FAILURE,
					     _("malloc() failed"));
		to = 0;
		(void) strcpy(fakeenv[to++], "TZ=");
		for (from = 0; environ[from] != NULL; ++from)
			if (strncmp(environ[from], "TZ=", 3) != 0)
				fakeenv[to++] = environ[from];
		fakeenv[to] = NULL;
		environ = fakeenv;
	}
	for (i = optind; i < argc; ++i) {
		static char	buf[MAX_STRING_LENGTH];

		(void) strcpy(&fakeenv[0][3], argv[i]);
		if (!vflag) {
			show(argv[i], now, FALSE);
			continue;
		}
		/*
		** Get lowest value of t.
		*/
#ifdef __APPLE__
		t = INT_MIN;
#else
		t = hibit;
		if (t > 0)		/* time_t is unsigned */
			t = 0;
#endif
		show(argv[i], t, TRUE);
		t += SECSPERHOUR * HOURSPERDAY;
		show(argv[i], t, TRUE);
		tm = *localtime(&t);
		(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
		for ( ; ; ) {
			if (cutoff != NULL && t >= cuttime)
				break;
			newt = t + SECSPERHOUR * 12;
			if (cutoff != NULL && newt >= cuttime)
				break;
#ifdef __APPLE__
			if (newt > INT_MAX)
				break;
#else
			if (newt <= t)
				break;
#endif
			newtm = *localtime(&newt);
			if (delta(&newtm, &tm) != (newt - t) ||
				newtm.tm_isdst != tm.tm_isdst ||
				strcmp(abbr(&newtm), buf) != 0) {
					newt = hunt(argv[i], t, newt);
					newtm = *localtime(&newt);
					(void) strncpy(buf, abbr(&newtm),
						(sizeof buf) - 1);
			}
			t = newt;
			tm = newtm;
		}
		/*
		** Get highest value of t.
		*/
#ifdef __APPLE__
		t = INT_MAX;
#else
		t = ~((time_t) 0);
		if (t < 0)		/* time_t is signed */
			t &= ~hibit;
#endif
		t -= SECSPERHOUR * HOURSPERDAY;
		show(argv[i], t, TRUE);
		t += SECSPERHOUR * HOURSPERDAY;
		show(argv[i], t, TRUE);
	}
	if (fflush(stdout) || ferror(stdout))
		errx(EXIT_FAILURE, _("error writing standard output"));
	exit(EXIT_SUCCESS);

	/* gcc -Wall pacifier */
	for ( ; ; )
		continue;
}

static void
usage(void)
{
	fprintf(stderr,
_("usage: zdump [--version] [-v] [-c cutoff] zonename ...\n"));
	exit(EXIT_FAILURE);
}

static time_t
hunt(char *name, time_t lot, time_t hit)
{
	time_t		t;
	struct tm	lotm;
	struct tm	tm;
	static char	loab[MAX_STRING_LENGTH];

	lotm = *localtime(&lot);
	(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
	while ((hit - lot) >= 2) {
		t = lot / 2 + hit / 2;
		if (t <= lot)
			++t;
		else if (t >= hit)
			--t;
		tm = *localtime(&t);
		if (delta(&tm, &lotm) == (t - lot) &&
			tm.tm_isdst == lotm.tm_isdst &&
			strcmp(abbr(&tm), loab) == 0) {
				lot = t;
				lotm = tm;
		} else	hit = t;
	}
	show(name, lot, TRUE);
	show(name, hit, TRUE);
	return hit;
}

/*
** Thanks to Paul Eggert (eggert@twinsun.com) for logic used in delta.
*/

static long
delta(struct tm *newp, struct tm *oldp)
{
	long	result;
	int	tmy;

	if (newp->tm_year < oldp->tm_year)
		return -delta(oldp, newp);
	result = 0;
	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
		result += DAYSPERNYEAR + isleap(tmy + TM_YEAR_BASE);
	result += newp->tm_yday - oldp->tm_yday;
	result *= HOURSPERDAY;
	result += newp->tm_hour - oldp->tm_hour;
	result *= MINSPERHOUR;
	result += newp->tm_min - oldp->tm_min;
	result *= SECSPERMIN;
	result += newp->tm_sec - oldp->tm_sec;
	return result;
}

static void
show(char *zone, time_t t, int v)
{
	struct tm *	tmp;

	(void) printf("%-*s  ", (int) longest, zone);
	if (v)
		(void) printf("%.24s UTC = ", asctime(gmtime(&t)));
	tmp = localtime(&t);
	(void) printf("%.24s", asctime(tmp));
	if (*abbr(tmp) != '\0')
		(void) printf(" %s", abbr(tmp));
	if (v) {
		(void) printf(" isdst=%d", tmp->tm_isdst);
#ifdef TM_GMTOFF
		(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
#endif /* defined TM_GMTOFF */
	}
	(void) printf("\n");
}

static char *
abbr(struct tm *tmp)
{
	char *		result;
	static char	nada;

	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
		return &nada;
	result = tzname[tmp->tm_isdst];
	return (result == NULL) ? &nada : result;
}
Commit	Line	Data
2fc1e207 A	1	static const char elsieid[] = "@(#)zdump.c 7.31";
	2
	3	#ifndef lint
cf37c299 A	4	#include <sys/cdefs.h>
cf37c299 A	5	__unused static const char rcsid[] =
ef8ad44b	6	"$FreeBSD: src/usr.sbin/zic/zdump.c,v 1.10 2008/02/19 07:09:19 ru Exp $";
2fc1e207	7	#endif /* not lint */
1815bff5 A	8
	9	/*
	10	** This code has been made independent of the rest of the time
	11	** conversion package to increase confidence in the verification it provides.
	12	** You can use this code to help in verifying other implementations.
	13	*/
	14
2fc1e207 A	15	#include <err.h>
	16	#include <stdio.h> /* for stdout, stderr */
	17	#include <stdlib.h> /* for exit, malloc, atoi */
	18	#include <string.h> /* for strcpy */
	19	#include <sys/types.h> /* for time_t */
	20	#include <time.h> /* for struct tm */
	21	#include <unistd.h>
ef8ad44b	22	#include <limits.h>
1815bff5 A	23
	24	#ifndef MAX_STRING_LENGTH
	25	#define MAX_STRING_LENGTH 1024
	26	#endif /* !defined MAX_STRING_LENGTH */
	27
	28	#ifndef TRUE
	29	#define TRUE 1
	30	#endif /* !defined TRUE */
	31
	32	#ifndef FALSE
	33	#define FALSE 0
	34	#endif /* !defined FALSE */
	35
	36	#ifndef EXIT_SUCCESS
	37	#define EXIT_SUCCESS 0
	38	#endif /* !defined EXIT_SUCCESS */
	39
	40	#ifndef EXIT_FAILURE
	41	#define EXIT_FAILURE 1
	42	#endif /* !defined EXIT_FAILURE */
	43
	44	#ifndef SECSPERMIN
	45	#define SECSPERMIN 60
	46	#endif /* !defined SECSPERMIN */
	47
	48	#ifndef MINSPERHOUR
	49	#define MINSPERHOUR 60
	50	#endif /* !defined MINSPERHOUR */
	51
	52	#ifndef SECSPERHOUR
	53	#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
	54	#endif /* !defined SECSPERHOUR */
	55
	56	#ifndef HOURSPERDAY
	57	#define HOURSPERDAY 24
	58	#endif /* !defined HOURSPERDAY */
	59
	60	#ifndef EPOCH_YEAR
	61	#define EPOCH_YEAR 1970
	62	#endif /* !defined EPOCH_YEAR */
	63
	64	#ifndef TM_YEAR_BASE
	65	#define TM_YEAR_BASE 1900
	66	#endif /* !defined TM_YEAR_BASE */
	67
	68	#ifndef DAYSPERNYEAR
	69	#define DAYSPERNYEAR 365
	70	#endif /* !defined DAYSPERNYEAR */
	71
	72	#ifndef isleap
	73	#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) \|\| ((y) % 400) == 0)
	74	#endif /* !defined isleap */
	75
	76	#if HAVE_GETTEXT - 0
	77	#include "locale.h" /* for setlocale */
	78	#include "libintl.h"
	79	#endif /* HAVE_GETTEXT - 0 */
	80
	81	#ifndef GNUC_or_lint
	82	#ifdef lint
	83	#define GNUC_or_lint
	84	#endif /* defined lint */
	85	#ifndef lint
	86	#ifdef __GNUC__
87	#define GNUC_or_lint
88	#endif /* defined __GNUC__ */
89	#endif /* !defined lint */
90	#endif /* !defined GNUC_or_lint */
91
92	#ifndef INITIALIZE
93	#ifdef GNUC_or_lint
94	#define INITIALIZE(x) ((x) = 0)
95	#endif /* defined GNUC_or_lint */
96	#ifndef GNUC_or_lint
97	#define INITIALIZE(x)
98	#endif /* !defined GNUC_or_lint */
99	#endif /* !defined INITIALIZE */
100
101	/*
102	** For the benefit of GNU folk...
103	** `_(MSGID)' uses the current locale's message library string for MSGID.
104	** The default is to use gettext if available, and use MSGID otherwise.
105	*/
106
107	#ifndef _
108	#if HAVE_GETTEXT - 0
109	#define _(msgid) gettext(msgid)
110	#else /* !(HAVE_GETTEXT - 0) */
111	#define _(msgid) msgid
112	#endif /* !(HAVE_GETTEXT - 0) */
113	#endif /* !defined _ */
114
115	#ifndef TZ_DOMAIN
116	#define TZ_DOMAIN "tz"
117	#endif /* !defined TZ_DOMAIN */
118
2fc1e207 A	119	#ifndef P
	120	#ifdef __STDC__
	121	#define P(x) x
	122	#endif /* defined __STDC__ */
	123	#ifndef __STDC__
	124	#define P(x) ()
	125	#endif /* !defined __STDC__ */
	126	#endif /* !defined P */
	127
1815bff5	128	extern char ** environ;
1815bff5 A	129	extern char * tzname[2];
1815bff5 A	130
2fc1e207 A	131	static char * abbr P((struct tm * tmp));
	132	static long delta P((struct tm * newp, struct tm * oldp));
	133	static time_t hunt P((char * name, time_t lot, time_t hit));
	134	static size_t longest;
	135	static void show P((char * zone, time_t t, int v));
	136	static void usage(void);
1815bff5 A	137
1815bff5 A	138	int
cf37c299	139	main(int argc, char *argv[])
1815bff5	140	{
cf37c299 A	141	int i;
	142	int c;
	143	int vflag;
	144	char * cutoff;
	145	int cutyear;
	146	long cuttime;
1815bff5 A	147	char ** fakeenv;
	148	time_t now;
	149	time_t t;
	150	time_t newt;
ef8ad44b A	151	#ifndef __APPLE__
	152	// <rdar://problem/6013740>
	153	// The approach of walking through every day from the minimum
	154	// possible time_t value to the maximum possible time_t value
	155	// falls apart with 64-bit time_t (takes too long to iterate,
	156	// and causes gmtime(3) and localtime(3) to return EOVERFLOW
	157	// which this code does not anticipate). Limiting the time_t
	158	// range to [INT_MIN:INT_MAX] even on LP64.
1815bff5	159	time_t hibit;
ef8ad44b	160	#endif
1815bff5 A	161	struct tm tm;
	162	struct tm newtm;
	163
	164	INITIALIZE(cuttime);
	165	#if HAVE_GETTEXT - 0
	166	(void) setlocale(LC_MESSAGES, "");
	167	#ifdef TZ_DOMAINDIR
	168	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
	169	#endif /* defined(TEXTDOMAINDIR) */
	170	(void) textdomain(TZ_DOMAIN);
	171	#endif /* HAVE_GETTEXT - 0 */
2fc1e207 A	172	for (i = 1; i < argc; ++i)
	173	if (strcmp(argv[i], "--version") == 0) {
	174	errx(EXIT_SUCCESS, "%s", elsieid);
	175	}
1815bff5 A	176	vflag = 0;
	177	cutoff = NULL;
	178	while ((c = getopt(argc, argv, "c:v")) == 'c' \|\| c == 'v')
	179	if (c == 'v')
	180	vflag = 1;
	181	else cutoff = optarg;
ef8ad44b	182	if ((c != -1) \|\|
1815bff5	183	(optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
2fc1e207	184	usage();
1815bff5 A	185	}
	186	if (cutoff != NULL) {
	187	int y;
	188
	189	cutyear = atoi(cutoff);
	190	cuttime = 0;
	191	for (y = EPOCH_YEAR; y < cutyear; ++y)
	192	cuttime += DAYSPERNYEAR + isleap(y);
	193	cuttime = SECSPERHOUR HOURSPERDAY;
	194	}
	195	(void) time(&now);
	196	longest = 0;
	197	for (i = optind; i < argc; ++i)
	198	if (strlen(argv[i]) > longest)
	199	longest = strlen(argv[i]);
ef8ad44b	200	#ifndef __APPLE__
1815bff5 A	201	for (hibit = 1; (hibit << 1) != 0; hibit <<= 1)
1815bff5 A	202	continue;
ef8ad44b	203	#endif
1815bff5	204	{
cf37c299 A	205	int from;
cf37c299 A	206	int to;
1815bff5 A	207
	208	for (i = 0; environ[i] != NULL; ++i)
	209	continue;
	210	fakeenv = (char *) malloc((size_t) ((i + 2)
	211	sizeof *fakeenv));
	212	if (fakeenv == NULL \|\|
	213	(fakeenv[0] = (char *) malloc((size_t) (longest +
2fc1e207 A	214	4))) == NULL)
	215	errx(EXIT_FAILURE,
	216	_("malloc() failed"));
1815bff5 A	217	to = 0;
	218	(void) strcpy(fakeenv[to++], "TZ=");
	219	for (from = 0; environ[from] != NULL; ++from)
	220	if (strncmp(environ[from], "TZ=", 3) != 0)
	221	fakeenv[to++] = environ[from];
	222	fakeenv[to] = NULL;
	223	environ = fakeenv;
	224	}
	225	for (i = optind; i < argc; ++i) {
	226	static char buf[MAX_STRING_LENGTH];
	227
	228	(void) strcpy(&fakeenv[0][3], argv[i]);
2fc1e207 A	229	if (!vflag) {
2fc1e207 A	230	show(argv[i], now, FALSE);
1815bff5	231	continue;
2fc1e207	232	}
1815bff5 A	233	/*
	234	** Get lowest value of t.
	235	*/
ef8ad44b A	236	#ifdef __APPLE__
	237	t = INT_MIN;
	238	#else
1815bff5 A	239	t = hibit;
	240	if (t > 0) /* time_t is unsigned */
	241	t = 0;
ef8ad44b	242	#endif
1815bff5 A	243	show(argv[i], t, TRUE);
	244	t += SECSPERHOUR * HOURSPERDAY;
	245	show(argv[i], t, TRUE);
	246	tm = *localtime(&t);
	247	(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
	248	for ( ; ; ) {
	249	if (cutoff != NULL && t >= cuttime)
	250	break;
	251	newt = t + SECSPERHOUR * 12;
	252	if (cutoff != NULL && newt >= cuttime)
	253	break;
ef8ad44b A	254	#ifdef __APPLE__
	255	if (newt > INT_MAX)
	256	break;
	257	#else
1815bff5 A	258	if (newt <= t)
1815bff5 A	259	break;
ef8ad44b	260	#endif
1815bff5 A	261	newtm = *localtime(&newt);
	262	if (delta(&newtm, &tm) != (newt - t) \|\|
	263	newtm.tm_isdst != tm.tm_isdst \|\|
	264	strcmp(abbr(&newtm), buf) != 0) {
	265	newt = hunt(argv[i], t, newt);
	266	newtm = *localtime(&newt);
	267	(void) strncpy(buf, abbr(&newtm),
	268	(sizeof buf) - 1);
	269	}
	270	t = newt;
	271	tm = newtm;
	272	}
	273	/*
	274	** Get highest value of t.
	275	*/
ef8ad44b A	276	#ifdef __APPLE__
	277	t = INT_MAX;
	278	#else
1815bff5 A	279	t = ~((time_t) 0);
	280	if (t < 0) /* time_t is signed */
	281	t &= ~hibit;
ef8ad44b	282	#endif
1815bff5 A	283	t -= SECSPERHOUR * HOURSPERDAY;
	284	show(argv[i], t, TRUE);
	285	t += SECSPERHOUR * HOURSPERDAY;
	286	show(argv[i], t, TRUE);
	287	}
2fc1e207 A	288	if (fflush(stdout) \|\| ferror(stdout))
2fc1e207 A	289	errx(EXIT_FAILURE, _("error writing standard output"));
1815bff5 A	290	exit(EXIT_SUCCESS);
	291
	292	/* gcc -Wall pacifier */
	293	for ( ; ; )
	294	continue;
	295	}
	296
2fc1e207 A	297	static void
	298	usage(void)
	299	{
	300	fprintf(stderr,
	301	_("usage: zdump [--version] [-v] [-c cutoff] zonename ...\n"));
	302	exit(EXIT_FAILURE);
	303	}
	304
1815bff5	305	static time_t
cf37c299	306	hunt(char *name, time_t lot, time_t hit)
1815bff5 A	307	{
	308	time_t t;
	309	struct tm lotm;
	310	struct tm tm;
	311	static char loab[MAX_STRING_LENGTH];
	312
	313	lotm = *localtime(&lot);
	314	(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
1815bff5 A	315	while ((hit - lot) >= 2) {
	316	t = lot / 2 + hit / 2;
	317	if (t <= lot)
	318	++t;
	319	else if (t >= hit)
	320	--t;
	321	tm = *localtime(&t);
	322	if (delta(&tm, &lotm) == (t - lot) &&
	323	tm.tm_isdst == lotm.tm_isdst &&
	324	strcmp(abbr(&tm), loab) == 0) {
	325	lot = t;
	326	lotm = tm;
	327	} else hit = t;
	328	}
	329	show(name, lot, TRUE);
	330	show(name, hit, TRUE);
	331	return hit;
	332	}
	333
	334	/*
	335	** Thanks to Paul Eggert (eggert@twinsun.com) for logic used in delta.
	336	*/
	337
	338	static long
cf37c299	339	delta(struct tm newp, struct tm oldp)
1815bff5 A	340	{
	341	long result;
	342	int tmy;
	343
	344	if (newp->tm_year < oldp->tm_year)
	345	return -delta(oldp, newp);
	346	result = 0;
	347	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
	348	result += DAYSPERNYEAR + isleap(tmy + TM_YEAR_BASE);
	349	result += newp->tm_yday - oldp->tm_yday;
	350	result *= HOURSPERDAY;
	351	result += newp->tm_hour - oldp->tm_hour;
	352	result *= MINSPERHOUR;
	353	result += newp->tm_min - oldp->tm_min;
	354	result *= SECSPERMIN;
	355	result += newp->tm_sec - oldp->tm_sec;
	356	return result;
	357	}
	358
1815bff5	359	static void
cf37c299	360	show(char *zone, time_t t, int v)
1815bff5 A	361	{
	362	struct tm * tmp;
	363
2fc1e207	364	(void) printf("%-*s ", (int) longest, zone);
1815bff5	365	if (v)
2fc1e207	366	(void) printf("%.24s UTC = ", asctime(gmtime(&t)));
1815bff5 A	367	tmp = localtime(&t);
	368	(void) printf("%.24s", asctime(tmp));
	369	if (*abbr(tmp) != '\0')
	370	(void) printf(" %s", abbr(tmp));
	371	if (v) {
	372	(void) printf(" isdst=%d", tmp->tm_isdst);
	373	#ifdef TM_GMTOFF
	374	(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
	375	#endif /* defined TM_GMTOFF */
	376	}
	377	(void) printf("\n");
	378	}
	379
	380	static char *
cf37c299	381	abbr(struct tm *tmp)
1815bff5	382	{
cf37c299	383	char * result;
1815bff5 A	384	static char nada;
	385
	386	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
	387	return &nada;
	388	result = tzname[tmp->tm_isdst];
	389	return (result == NULL) ? &nada : result;
	390	}