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

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

#ifndef lint
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(argc, argv)
int	argc;
char *	argv[];
{
	register int		i;
	register int		c;
	register int		vflag;
	register char *		cutoff;
	register int		cutyear;
	register 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
	{
		register int	from;
		register 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(name, lot, hit)
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(newp, oldp)
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(zone, t, v)
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(tmp)
struct tm *	tmp;
{
	register 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
	4	static const char rcsid[] =
ef8ad44b	5	"$FreeBSD: src/usr.sbin/zic/zdump.c,v 1.10 2008/02/19 07:09:19 ru Exp $";
2fc1e207	6	#endif /* not lint */
1815bff5 A	7
	8	/*
	9	** This code has been made independent of the rest of the time
	10	** conversion package to increase confidence in the verification it provides.
	11	** You can use this code to help in verifying other implementations.
	12	*/
	13
2fc1e207 A	14	#include <err.h>
	15	#include <stdio.h> /* for stdout, stderr */
	16	#include <stdlib.h> /* for exit, malloc, atoi */
	17	#include <string.h> /* for strcpy */
	18	#include <sys/types.h> /* for time_t */
	19	#include <time.h> /* for struct tm */
	20	#include <unistd.h>
ef8ad44b	21	#include <limits.h>
1815bff5 A	22
	23	#ifndef MAX_STRING_LENGTH
	24	#define MAX_STRING_LENGTH 1024
	25	#endif /* !defined MAX_STRING_LENGTH */
	26
	27	#ifndef TRUE
	28	#define TRUE 1
	29	#endif /* !defined TRUE */
	30
	31	#ifndef FALSE
	32	#define FALSE 0
	33	#endif /* !defined FALSE */
	34
	35	#ifndef EXIT_SUCCESS
	36	#define EXIT_SUCCESS 0
	37	#endif /* !defined EXIT_SUCCESS */
	38
	39	#ifndef EXIT_FAILURE
	40	#define EXIT_FAILURE 1
	41	#endif /* !defined EXIT_FAILURE */
	42
	43	#ifndef SECSPERMIN
	44	#define SECSPERMIN 60
	45	#endif /* !defined SECSPERMIN */
	46
	47	#ifndef MINSPERHOUR
	48	#define MINSPERHOUR 60
	49	#endif /* !defined MINSPERHOUR */
	50
	51	#ifndef SECSPERHOUR
	52	#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
	53	#endif /* !defined SECSPERHOUR */
	54
	55	#ifndef HOURSPERDAY
	56	#define HOURSPERDAY 24
	57	#endif /* !defined HOURSPERDAY */
	58
	59	#ifndef EPOCH_YEAR
	60	#define EPOCH_YEAR 1970
	61	#endif /* !defined EPOCH_YEAR */
	62
	63	#ifndef TM_YEAR_BASE
	64	#define TM_YEAR_BASE 1900
	65	#endif /* !defined TM_YEAR_BASE */
	66
	67	#ifndef DAYSPERNYEAR
	68	#define DAYSPERNYEAR 365
	69	#endif /* !defined DAYSPERNYEAR */
	70
	71	#ifndef isleap
	72	#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) \|\| ((y) % 400) == 0)
	73	#endif /* !defined isleap */
	74
	75	#if HAVE_GETTEXT - 0
	76	#include "locale.h" /* for setlocale */
	77	#include "libintl.h"
	78	#endif /* HAVE_GETTEXT - 0 */
	79
	80	#ifndef GNUC_or_lint
	81	#ifdef lint
	82	#define GNUC_or_lint
	83	#endif /* defined lint */
	84	#ifndef lint
	85	#ifdef __GNUC__
86	#define GNUC_or_lint
87	#endif /* defined __GNUC__ */
88	#endif /* !defined lint */
89	#endif /* !defined GNUC_or_lint */
90
91	#ifndef INITIALIZE
92	#ifdef GNUC_or_lint
93	#define INITIALIZE(x) ((x) = 0)
94	#endif /* defined GNUC_or_lint */
95	#ifndef GNUC_or_lint
96	#define INITIALIZE(x)
97	#endif /* !defined GNUC_or_lint */
98	#endif /* !defined INITIALIZE */
99
100	/*
101	** For the benefit of GNU folk...
102	** `_(MSGID)' uses the current locale's message library string for MSGID.
103	** The default is to use gettext if available, and use MSGID otherwise.
104	*/
105
106	#ifndef _
107	#if HAVE_GETTEXT - 0
108	#define _(msgid) gettext(msgid)
109	#else /* !(HAVE_GETTEXT - 0) */
110	#define _(msgid) msgid
111	#endif /* !(HAVE_GETTEXT - 0) */
112	#endif /* !defined _ */
113
114	#ifndef TZ_DOMAIN
115	#define TZ_DOMAIN "tz"
116	#endif /* !defined TZ_DOMAIN */
117
2fc1e207 A	118	#ifndef P
	119	#ifdef __STDC__
	120	#define P(x) x
	121	#endif /* defined __STDC__ */
	122	#ifndef __STDC__
	123	#define P(x) ()
	124	#endif /* !defined __STDC__ */
	125	#endif /* !defined P */
	126
1815bff5	127	extern char ** environ;
1815bff5 A	128	extern char * tzname[2];
1815bff5 A	129
2fc1e207 A	130	static char * abbr P((struct tm * tmp));
	131	static long delta P((struct tm * newp, struct tm * oldp));
	132	static time_t hunt P((char * name, time_t lot, time_t hit));
	133	static size_t longest;
	134	static void show P((char * zone, time_t t, int v));
	135	static void usage(void);
1815bff5 A	136
	137	int
	138	main(argc, argv)
	139	int argc;
	140	char * argv[];
	141	{
	142	register int i;
	143	register int c;
	144	register int vflag;
	145	register char * cutoff;
	146	register int cutyear;
	147	register long cuttime;
	148	char ** fakeenv;
	149	time_t now;
	150	time_t t;
	151	time_t newt;
ef8ad44b A	152	#ifndef __APPLE__
	153	// <rdar://problem/6013740>
	154	// The approach of walking through every day from the minimum
	155	// possible time_t value to the maximum possible time_t value
	156	// falls apart with 64-bit time_t (takes too long to iterate,
	157	// and causes gmtime(3) and localtime(3) to return EOVERFLOW
	158	// which this code does not anticipate). Limiting the time_t
	159	// range to [INT_MIN:INT_MAX] even on LP64.
1815bff5	160	time_t hibit;
ef8ad44b	161	#endif
1815bff5 A	162	struct tm tm;
	163	struct tm newtm;
	164
	165	INITIALIZE(cuttime);
	166	#if HAVE_GETTEXT - 0
	167	(void) setlocale(LC_MESSAGES, "");
	168	#ifdef TZ_DOMAINDIR
	169	(void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
	170	#endif /* defined(TEXTDOMAINDIR) */
	171	(void) textdomain(TZ_DOMAIN);
	172	#endif /* HAVE_GETTEXT - 0 */
2fc1e207 A	173	for (i = 1; i < argc; ++i)
	174	if (strcmp(argv[i], "--version") == 0) {
	175	errx(EXIT_SUCCESS, "%s", elsieid);
	176	}
1815bff5 A	177	vflag = 0;
	178	cutoff = NULL;
	179	while ((c = getopt(argc, argv, "c:v")) == 'c' \|\| c == 'v')
	180	if (c == 'v')
	181	vflag = 1;
	182	else cutoff = optarg;
ef8ad44b	183	if ((c != -1) \|\|
1815bff5	184	(optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
2fc1e207	185	usage();
1815bff5 A	186	}
	187	if (cutoff != NULL) {
	188	int y;
	189
	190	cutyear = atoi(cutoff);
	191	cuttime = 0;
	192	for (y = EPOCH_YEAR; y < cutyear; ++y)
	193	cuttime += DAYSPERNYEAR + isleap(y);
	194	cuttime = SECSPERHOUR HOURSPERDAY;
	195	}
	196	(void) time(&now);
	197	longest = 0;
	198	for (i = optind; i < argc; ++i)
	199	if (strlen(argv[i]) > longest)
	200	longest = strlen(argv[i]);
ef8ad44b	201	#ifndef __APPLE__
1815bff5 A	202	for (hibit = 1; (hibit << 1) != 0; hibit <<= 1)
1815bff5 A	203	continue;
ef8ad44b	204	#endif
1815bff5 A	205	{
	206	register int from;
	207	register int to;
	208
	209	for (i = 0; environ[i] != NULL; ++i)
	210	continue;
	211	fakeenv = (char *) malloc((size_t) ((i + 2)
	212	sizeof *fakeenv));
	213	if (fakeenv == NULL \|\|
	214	(fakeenv[0] = (char *) malloc((size_t) (longest +
2fc1e207 A	215	4))) == NULL)
	216	errx(EXIT_FAILURE,
	217	_("malloc() failed"));
1815bff5 A	218	to = 0;
	219	(void) strcpy(fakeenv[to++], "TZ=");
	220	for (from = 0; environ[from] != NULL; ++from)
	221	if (strncmp(environ[from], "TZ=", 3) != 0)
	222	fakeenv[to++] = environ[from];
	223	fakeenv[to] = NULL;
	224	environ = fakeenv;
	225	}
	226	for (i = optind; i < argc; ++i) {
	227	static char buf[MAX_STRING_LENGTH];
	228
	229	(void) strcpy(&fakeenv[0][3], argv[i]);
2fc1e207 A	230	if (!vflag) {
2fc1e207 A	231	show(argv[i], now, FALSE);
1815bff5	232	continue;
2fc1e207	233	}
1815bff5 A	234	/*
	235	** Get lowest value of t.
	236	*/
ef8ad44b A	237	#ifdef __APPLE__
	238	t = INT_MIN;
	239	#else
1815bff5 A	240	t = hibit;
	241	if (t > 0) /* time_t is unsigned */
	242	t = 0;
ef8ad44b	243	#endif
1815bff5 A	244	show(argv[i], t, TRUE);
	245	t += SECSPERHOUR * HOURSPERDAY;
	246	show(argv[i], t, TRUE);
	247	tm = *localtime(&t);
	248	(void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
	249	for ( ; ; ) {
	250	if (cutoff != NULL && t >= cuttime)
	251	break;
	252	newt = t + SECSPERHOUR * 12;
	253	if (cutoff != NULL && newt >= cuttime)
	254	break;
ef8ad44b A	255	#ifdef __APPLE__
	256	if (newt > INT_MAX)
	257	break;
	258	#else
1815bff5 A	259	if (newt <= t)
1815bff5 A	260	break;
ef8ad44b	261	#endif
1815bff5 A	262	newtm = *localtime(&newt);
	263	if (delta(&newtm, &tm) != (newt - t) \|\|
	264	newtm.tm_isdst != tm.tm_isdst \|\|
	265	strcmp(abbr(&newtm), buf) != 0) {
	266	newt = hunt(argv[i], t, newt);
	267	newtm = *localtime(&newt);
	268	(void) strncpy(buf, abbr(&newtm),
	269	(sizeof buf) - 1);
	270	}
	271	t = newt;
	272	tm = newtm;
	273	}
	274	/*
	275	** Get highest value of t.
	276	*/
ef8ad44b A	277	#ifdef __APPLE__
	278	t = INT_MAX;
	279	#else
1815bff5 A	280	t = ~((time_t) 0);
	281	if (t < 0) /* time_t is signed */
	282	t &= ~hibit;
ef8ad44b	283	#endif
1815bff5 A	284	t -= SECSPERHOUR * HOURSPERDAY;
	285	show(argv[i], t, TRUE);
	286	t += SECSPERHOUR * HOURSPERDAY;
	287	show(argv[i], t, TRUE);
	288	}
2fc1e207 A	289	if (fflush(stdout) \|\| ferror(stdout))
2fc1e207 A	290	errx(EXIT_FAILURE, _("error writing standard output"));
1815bff5 A	291	exit(EXIT_SUCCESS);
	292
	293	/* gcc -Wall pacifier */
	294	for ( ; ; )
	295	continue;
	296	}
	297
2fc1e207 A	298	static void
	299	usage(void)
	300	{
	301	fprintf(stderr,
	302	_("usage: zdump [--version] [-v] [-c cutoff] zonename ...\n"));
	303	exit(EXIT_FAILURE);
	304	}
	305
1815bff5 A	306	static time_t
	307	hunt(name, lot, hit)
	308	char * name;
	309	time_t lot;
	310	time_t hit;
	311	{
	312	time_t t;
	313	struct tm lotm;
	314	struct tm tm;
	315	static char loab[MAX_STRING_LENGTH];
	316
	317	lotm = *localtime(&lot);
	318	(void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
1815bff5 A	319	while ((hit - lot) >= 2) {
	320	t = lot / 2 + hit / 2;
	321	if (t <= lot)
	322	++t;
	323	else if (t >= hit)
	324	--t;
	325	tm = *localtime(&t);
	326	if (delta(&tm, &lotm) == (t - lot) &&
	327	tm.tm_isdst == lotm.tm_isdst &&
	328	strcmp(abbr(&tm), loab) == 0) {
	329	lot = t;
	330	lotm = tm;
	331	} else hit = t;
	332	}
	333	show(name, lot, TRUE);
	334	show(name, hit, TRUE);
	335	return hit;
	336	}
	337
	338	/*
	339	** Thanks to Paul Eggert (eggert@twinsun.com) for logic used in delta.
	340	*/
	341
	342	static long
	343	delta(newp, oldp)
	344	struct tm * newp;
	345	struct tm * oldp;
	346	{
	347	long result;
	348	int tmy;
	349
	350	if (newp->tm_year < oldp->tm_year)
	351	return -delta(oldp, newp);
	352	result = 0;
	353	for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
	354	result += DAYSPERNYEAR + isleap(tmy + TM_YEAR_BASE);
	355	result += newp->tm_yday - oldp->tm_yday;
	356	result *= HOURSPERDAY;
	357	result += newp->tm_hour - oldp->tm_hour;
	358	result *= MINSPERHOUR;
	359	result += newp->tm_min - oldp->tm_min;
	360	result *= SECSPERMIN;
	361	result += newp->tm_sec - oldp->tm_sec;
	362	return result;
	363	}
	364
1815bff5 A	365	static void
	366	show(zone, t, v)
	367	char * zone;
	368	time_t t;
	369	int v;
	370	{
	371	struct tm * tmp;
	372
2fc1e207	373	(void) printf("%-*s ", (int) longest, zone);
1815bff5	374	if (v)
2fc1e207	375	(void) printf("%.24s UTC = ", asctime(gmtime(&t)));
1815bff5 A	376	tmp = localtime(&t);
	377	(void) printf("%.24s", asctime(tmp));
	378	if (*abbr(tmp) != '\0')
	379	(void) printf(" %s", abbr(tmp));
	380	if (v) {
	381	(void) printf(" isdst=%d", tmp->tm_isdst);
	382	#ifdef TM_GMTOFF
	383	(void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
	384	#endif /* defined TM_GMTOFF */
	385	}
	386	(void) printf("\n");
	387	}
	388
	389	static char *
	390	abbr(tmp)
	391	struct tm * tmp;
	392	{
	393	register char * result;
	394	static char nada;
	395
	396	if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
	397	return &nada;
	398	result = tzname[tmp->tm_isdst];
	399	return (result == NULL) ? &nada : result;
	400	}