.

timezone/zic.c

@@ -1,18 +1,15 @@
+static char	elsieid[] = "@(#)zic.c	7.128";
+
 /*
-** This file is in the public domain, so clarified as of
-** 2006-07-17 by Arthur David Olson.
+** Regardless of the type of time_t, we do our work using this type.
 */
 
-static char	elsieid[] = "@(#)zic.c	8.7";
+typedef int	zic_t;
 
 #include "private.h"
 #include "locale.h"
 #include "tzfile.h"
 
-#define	ZIC_VERSION	'2'
-
-typedef int_fast64_t	zic_t;
-
 #ifndef ZIC_MAX_ABBR_LEN_WO_WARN
 #define ZIC_MAX_ABBR_LEN_WO_WARN	6
 #endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
@@ -39,11 +36,6 @@ typedef int_fast64_t	zic_t;
 #define isascii(x) 1
 #endif
 
-#define OFFSET_STRLEN_MAXIMUM	(7 + INT_STRLEN_MAXIMUM(long))
-#define RULE_STRLEN_MAXIMUM	8	/* "Mdd.dd.d" */
-
-#define end(cp)	(strchr((cp), '\0'))
-
 struct rule {
 	const char *	r_filename;
 	int		r_linenum;
@@ -52,8 +44,6 @@ struct rule {
 	int		r_loyear;	/* for example, 1986 */
 	int		r_hiyear;	/* for example, 1986 */
 	const char *	r_yrtype;
-	int		r_lowasnum;
-	int		r_hiwasnum;
 
 	int		r_month;	/* 0..11 */
 
@@ -113,10 +103,9 @@ static void	adjleap P((void));
 static void	associate P((void));
 static int	ciequal P((const char * ap, const char * bp));
 static void	convert P((long val, char * buf));
-static void	convert64 P((zic_t val, char * buf));
 static void	dolink P((const char * fromfile, const char * tofile));
 static void	doabbr P((char * abbr, const char * format,
-			const char * letters, int isdst, int doquotes));
+			const char * letters, int isdst));
 static void	eat P((const char * name, int num));
 static void	eats P((const char * name, int num,
 			const char * rname, int rnum));
@@ -132,7 +121,6 @@ static void	inrule P((char ** fields, int nfields));
 static int	inzcont P((char ** fields, int nfields));
 static int	inzone P((char ** fields, int nfields));
 static int	inzsub P((char ** fields, int nfields, int iscont));
-static int	is32 P((zic_t x));
 static int	itsabbr P((const char * abbr, const char * word));
 static int	itsdir P((const char * name));
 static int	lowerit P((int c));
@@ -142,22 +130,16 @@ static void	newabbr P((const char * abbr));
 static long	oadd P((long t1, long t2));
 static void	outzone P((const struct zone * zp, int ntzones));
 static void	puttzcode P((long code, FILE * fp));
-static void	puttzcode64 P((zic_t code, FILE * fp));
 static int	rcomp P((const void * leftp, const void * rightp));
 static zic_t	rpytime P((const struct rule * rp, int wantedy));
 static void	rulesub P((struct rule * rp,
 			const char * loyearp, const char * hiyearp,
 			const char * typep, const char * monthp,
 			const char * dayp, const char * timep));
-static int 	stringoffset P((char * result, long offset));
-static int	stringrule P((char * result, const struct rule * rp,
-			long dstoff, long gmtoff));
-static void 	stringzone P((char * result,
-			const struct zone * zp, int ntzones));
 static void	setboundaries P((void));
 static zic_t	tadd P((zic_t t1, long t2));
 static void	usage P((void));
-static void	writezone P((const char * name, const char * string));
+static void	writezone P((const char * name));
 static int	yearistype P((int year, const char * type));
 
 #if !HAVE_STRERROR
@@ -168,16 +150,13 @@ static int		charcnt;
 static int		errors;
 static const char *	filename;
 static int		leapcnt;
-static int		leapseen;
-static int		leapminyear;
-static int		leapmaxyear;
 static int		linenum;
-static int		max_abbrvar_len;
-static int		max_format_len;
 static zic_t		max_time;
 static int		max_year;
+static int		max_year_representable;
 static zic_t		min_time;
 static int		min_year;
+static int		min_year_representable;
 static int		noise;
 static const char *	rfilename;
 static int		rlinenum;
@@ -474,7 +453,7 @@ static void
 usage P((void))
 {
 	(void) fprintf(stderr, _("%s: usage is %s \
-[ --version ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
+[ --version ] [ -s ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
 \t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n"),
 		progname, progname);
 	exit(EXIT_FAILURE);
@@ -485,6 +464,7 @@ static const char *	lcltime;
 static const char *	directory;
 static const char *	leapsec;
 static const char *	yitcommand;
+static int		sflag = FALSE;
 
 int
 main(argc, argv)
@@ -506,11 +486,6 @@ char *	argv[];
 	(void) textdomain(TZ_DOMAIN);
 #endif /* HAVE_GETTEXT */
 	progname = argv[0];
-	if (TYPE_BIT(zic_t) < 64) {
-		(void) fprintf(stderr, "%s: %s\n", progname,
-			_("wild compilation-time specification of zic_t"));
-		exit(EXIT_FAILURE);
-	}
 	for (i = 1; i < argc; ++i)
 		if (strcmp(argv[i], "--version") == 0) {
 			(void) printf("%s\n", elsieid);
@@ -574,7 +549,7 @@ _("%s: More than one -L option specified\n"),
 				noise = TRUE;
 				break;
 			case 's':
-				(void) printf("%s: -s ignored\n", progname);
+				sflag = TRUE;
 				break;
 		}
 	if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
@@ -696,17 +671,54 @@ warning(_("hard link failed, symbolic link used"));
 	ifree(toname);
 }
 
-#define TIME_T_BITS_IN_FILE	64
+#ifndef INT_MAX
+#define INT_MAX	((int) (((unsigned)~0)>>1))
+#endif /* !defined INT_MAX */
+
+#ifndef INT_MIN
+#define INT_MIN	((int) ~(((unsigned)~0)>>1))
+#endif /* !defined INT_MIN */
+
+/*
+** The tz file format currently allows at most 32-bit quantities.
+** This restriction should be removed before signed 32-bit values
+** wrap around in 2038, but unfortunately this will require a
+** change to the tz file format.
+*/
+
+#define MAX_BITS_IN_FILE	32
+#define TIME_T_BITS_IN_FILE	((TYPE_BIT(zic_t) < MAX_BITS_IN_FILE) ? \
+					TYPE_BIT(zic_t) : MAX_BITS_IN_FILE)
 
 static void
 setboundaries P((void))
 {
 	register int	i;
 
-	min_time = -1;
-	for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
-		min_time *= 2;
-	max_time = -(min_time + 1);
+	if (TYPE_SIGNED(zic_t)) {
+		min_time = -1;
+		for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
+			min_time *= 2;
+		max_time = -(min_time + 1);
+		if (sflag)
+			min_time = 0;
+	} else {
+		min_time = 0;
+		max_time = 2 - sflag;
+		for (i = 0; i < TIME_T_BITS_IN_FILE - 1; ++i)
+			max_time *= 2;
+		--max_time;
+	}
+	{
+		time_t	t;
+
+		t = (time_t) min_time;
+		min_year = TM_YEAR_BASE + gmtime(&t)->tm_year;
+		t = (time_t) max_time;
+		max_year = TM_YEAR_BASE + gmtime(&t)->tm_year;
+	}
+	min_year_representable = min_year;
+	max_year_representable = max_year;
 }
 
 static int
@@ -981,8 +993,6 @@ const int		nfields;
 		fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
 	r.r_name = ecpyalloc(fields[RF_NAME]);
 	r.r_abbrvar = ecpyalloc(fields[RF_ABBRVAR]);
-	if (max_abbrvar_len < strlen(r.r_abbrvar))
-		max_abbrvar_len = strlen(r.r_abbrvar);
 	rules = (struct rule *) (void *) erealloc((char *) rules,
 		(int) ((nrules + 1) * sizeof *rules));
 	rules[nrules++] = r;
@@ -1088,8 +1098,6 @@ const int		iscont;
 	}
 	z.z_rule = ecpyalloc(fields[i_rule]);
 	z.z_format = ecpyalloc(fields[i_format]);
-	if (max_format_len < strlen(z.z_format))
-		max_format_len = strlen(z.z_format);
 	hasuntil = nfields > i_untilyear;
 	if (hasuntil) {
 		z.z_untilrule.r_filename = filename;
@@ -1151,11 +1159,6 @@ const int		nfields;
 		error(_("invalid leaping year"));
 		return;
 	}
-	if (!leapseen || leapmaxyear < year)
-		leapmaxyear = year;
-	if (!leapseen || leapminyear > year)
-		leapminyear = year;
-	leapseen = TRUE;
 	j = EPOCH_YEAR;
 	while (j != year) {
 		if (year > j) {
@@ -1310,8 +1313,7 @@ const char * const		timep;
 	*/
 	cp = loyearp;
 	lp = byword(cp, begin_years);
-	rp->r_lowasnum = lp == NULL;
-	if (!rp->r_lowasnum) switch ((int) lp->l_value) {
+	if (lp != NULL) switch ((int) lp->l_value) {
 		case YR_MINIMUM:
 			rp->r_loyear = INT_MIN;
 			break;
@@ -1326,11 +1328,14 @@ const char * const		timep;
 	} else if (sscanf(cp, scheck(cp, "%d"), &rp->r_loyear) != 1) {
 		error(_("invalid starting year"));
 		return;
+	} else if (noise) {
+		if (rp->r_loyear < min_year_representable)
+			warning(_("starting year too low to be represented"));
+		else if (rp->r_loyear > max_year_representable)
+			warning(_("starting year too high to be represented"));
 	}
 	cp = hiyearp;
-	lp = byword(cp, end_years);
-	rp->r_hiwasnum = lp == NULL;
-	if (!rp->r_hiwasnum) switch ((int) lp->l_value) {
+	if ((lp = byword(cp, end_years)) != NULL) switch ((int) lp->l_value) {
 		case YR_MINIMUM:
 			rp->r_hiyear = INT_MIN;
 			break;
@@ -1348,6 +1353,11 @@ const char * const		timep;
 	} else if (sscanf(cp, scheck(cp, "%d"), &rp->r_hiyear) != 1) {
 		error(_("invalid ending year"));
 		return;
+	} else if (noise) {
+		if (rp->r_loyear < min_year_representable)
+			warning(_("ending year too low to be represented"));
+		else if (rp->r_loyear > max_year_representable)
+			warning(_("ending year too high to be represented"));
 	}
 	if (rp->r_loyear > rp->r_hiyear) {
 		error(_("starting year greater than ending year"));
@@ -1362,6 +1372,8 @@ const char * const		timep;
 		}
 		rp->r_yrtype = ecpyalloc(typep);
 	}
+	if (rp->r_loyear < min_year && rp->r_loyear > 0)
+		min_year = rp->r_loyear;
 	/*
 	** Day work.
 	** Accept things such as:
@@ -1415,24 +1427,12 @@ const long	val;
 char * const	buf;
 {
 	register int	i;
-	register int	shift;
+	register long	shift;
 
 	for (i = 0, shift = 24; i < 4; ++i, shift -= 8)
 		buf[i] = val >> shift;
 }
 
-static void
-convert64(val, buf)
-const zic_t	val;
-char * const	buf;
-{
-	register int	i;
-	register int	shift;
-
-	for (i = 0, shift = 56; i < 8; ++i, shift -= 8)
-		buf[i] = val >> shift;
-}
-
 static void
 puttzcode(val, fp)
 const long	val;
@@ -1444,50 +1444,28 @@ FILE * const	fp;
 	(void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
 }
 
-static void
-puttzcode64(val, fp)
-const zic_t	val;
-FILE * const	fp;
-{
-	char	buf[8];
-
-	convert64(val, buf);
-	(void) fwrite((void *) buf, (size_t) sizeof buf, (size_t) 1, fp);
-}
-
 static int
 atcomp(avp, bvp)
-const void *	avp;
-const void *	bvp;
+void *	avp;
+void *	bvp;
 {
-	const zic_t	a = ((const struct attype *) avp)->at;
-	const zic_t	b = ((const struct attype *) bvp)->at;
-
-	return (a < b) ? -1 : (a > b);
-}
-
-static int
-is32(x)
-const zic_t	x;
-{
-	return INT32_MIN <= x && x <= INT32_MAX;
+	if (((struct attype *) avp)->at < ((struct attype *) bvp)->at)
+		return -1;
+	else if (((struct attype *) avp)->at > ((struct attype *) bvp)->at)
+		return 1;
+	else	return 0;
 }
 
 static void
-writezone(name, string)
+writezone(name)
 const char * const	name;
-const char * const	string;
 {
-	register FILE *			fp;
-	register int			i, j;
-	register int			leapcnt32, leapi32;
-	register int			timecnt32, timei32;
-	register int			pass;
-	static char *			fullname;
-	static const struct tzhead	tzh0;
-	static struct tzhead		tzh;
-	zic_t				ats[TZ_MAX_TIMES];
-	unsigned char			types[TZ_MAX_TIMES];
+	register FILE *		fp;
+	register int		i, j;
+	static char *		fullname;
+	static struct tzhead	tzh;
+	zic_t			ats[TZ_MAX_TIMES];
+	unsigned char		types[TZ_MAX_TIMES];
 
 	/*
 	** Sort.
@@ -1531,36 +1509,6 @@ const char * const	string;
 		ats[i] = attypes[i].at;
 		types[i] = attypes[i].type;
 	}
-	/*
-	** Correct for leap seconds.
-	*/
-	for (i = 0; i < timecnt; ++i) {
-		j = leapcnt;
-		while (--j >= 0)
-			if (ats[i] > trans[j] - corr[j]) {
-				ats[i] = tadd(ats[i], corr[j]);
-				break;
-			}
-	}
-	/*
-	** Figure out 32-bit-limited starts and counts.
-	*/
-	timecnt32 = timecnt;
-	timei32 = 0;
-	leapcnt32 = leapcnt;
-	leapi32 = 0;
-	while (timecnt32 > 0 && !is32(ats[timecnt32 - 1]))
-		--timecnt32;
-	while (timecnt32 > 0 && !is32(ats[timei32])) {
-		--timecnt32;
-		++timei32;
-	}
-	while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
-		--leapcnt32;
-	while (leapcnt32 > 0 && !is32(trans[leapi32])) {
-		--leapcnt32;
-		++leapi32;
-	}
 	fullname = erealloc(fullname,
 		(int) (strlen(directory) + 1 + strlen(name) + 1));
 	(void) sprintf(fullname, "%s/%s", directory, name);
@@ -1585,150 +1533,67 @@ const char * const	string;
 			exit(EXIT_FAILURE);
 		}
 	}
-	for (pass = 1; pass <= 2; ++pass) {
-		register int	thistimei, thistimecnt;
-		register int	thisleapi, thisleapcnt;
-		register int	thistimelim, thisleaplim;
-		int		writetype[TZ_MAX_TIMES];
-		int		typemap[TZ_MAX_TYPES];
-		register int	thistypecnt;
-		char		thischars[TZ_MAX_CHARS];
-		char		thischarcnt;
-		int 		indmap[TZ_MAX_CHARS];
-
-		if (pass == 1) {
-			thistimei = timei32;
-			thistimecnt = timecnt32;
-			thisleapi = leapi32;
-			thisleapcnt = leapcnt32;
-		} else {
-			thistimei = 0;
-			thistimecnt = timecnt;
-			thisleapi = 0;
-			thisleapcnt = leapcnt;
-		}
-		thistimelim = thistimei + thistimecnt;
-		thisleaplim = thisleapi + thisleapcnt;
-		for (i = 0; i < typecnt; ++i)
-			writetype[i] = thistimecnt == timecnt;
-		if (thistimecnt == 0) {
-			/*
-			** No transition times fall in the current
-			** (32- or 64-bit) window.
-			*/
-			if (typecnt != 0)
-				writetype[typecnt - 1] = TRUE;
-		} else {
-			for (i = thistimei - 1; i < thistimelim; ++i)
-				if (i >= 0)
-					writetype[types[i]] = TRUE;
-			/*
-			** For America/Godthab and Antarctica/Palmer
-			*/
-			if (thistimei == 0)
-				writetype[0] = TRUE;
-		}
-		thistypecnt = 0;
-		for (i = 0; i < typecnt; ++i)
-			typemap[i] = writetype[i] ?  thistypecnt++ : -1;
-		for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i)
-			indmap[i] = -1;
-		thischarcnt = 0;
-		for (i = 0; i < typecnt; ++i) {
-			register char *	thisabbr;
-
-			if (!writetype[i])
-				continue;
-			if (indmap[abbrinds[i]] >= 0)
-				continue;
-			thisabbr = &chars[abbrinds[i]];
-			for (j = 0; j < thischarcnt; ++j)
-				if (strcmp(&thischars[j], thisabbr) == 0)
-					break;
-			if (j == thischarcnt) {
-				(void) strcpy(&thischars[(int) thischarcnt],
-					thisabbr);
-				thischarcnt += strlen(thisabbr) + 1;
-			}
-			indmap[abbrinds[i]] = j;
-		}
+	convert(eitol(typecnt), tzh.tzh_ttisgmtcnt);
+	convert(eitol(typecnt), tzh.tzh_ttisstdcnt);
+	convert(eitol(leapcnt), tzh.tzh_leapcnt);
+	convert(eitol(timecnt), tzh.tzh_timecnt);
+	convert(eitol(typecnt), tzh.tzh_typecnt);
+	convert(eitol(charcnt), tzh.tzh_charcnt);
+	(void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
 #define DO(field)	(void) fwrite((void *) tzh.field, \
 				(size_t) sizeof tzh.field, (size_t) 1, fp)
-		tzh = tzh0;
-		(void) strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
-		tzh.tzh_version[0] = ZIC_VERSION;
-		convert(eitol(thistypecnt), tzh.tzh_ttisgmtcnt);
-		convert(eitol(thistypecnt), tzh.tzh_ttisstdcnt);
-		convert(eitol(thisleapcnt), tzh.tzh_leapcnt);
-		convert(eitol(thistimecnt), tzh.tzh_timecnt);
-		convert(eitol(thistypecnt), tzh.tzh_typecnt);
-		convert(eitol(thischarcnt), tzh.tzh_charcnt);
-		DO(tzh_magic);
-		DO(tzh_version);
-		DO(tzh_reserved);
-		DO(tzh_ttisgmtcnt);
-		DO(tzh_ttisstdcnt);
-		DO(tzh_leapcnt);
-		DO(tzh_timecnt);
-		DO(tzh_typecnt);
-		DO(tzh_charcnt);
+	DO(tzh_magic);
+	DO(tzh_reserved);
+	DO(tzh_ttisgmtcnt);
+	DO(tzh_ttisstdcnt);
+	DO(tzh_leapcnt);
+	DO(tzh_timecnt);
+	DO(tzh_typecnt);
+	DO(tzh_charcnt);
 #undef DO
-		for (i = thistimei; i < thistimelim; ++i)
-			if (pass == 1)
-				puttzcode((long) ats[i], fp);
-			else	puttzcode64(ats[i], fp);
-		for (i = thistimei; i < thistimelim; ++i) {
-			unsigned char	uc;
-
-			uc = typemap[types[i]];
-			(void) fwrite((void *) &uc,
-				(size_t) sizeof uc,
-				(size_t) 1,
-				fp);
-		}
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i]) {
-				puttzcode(gmtoffs[i], fp);
-				(void) putc(isdsts[i], fp);
-				(void) putc((unsigned char) indmap[abbrinds[i]], fp);
+	for (i = 0; i < timecnt; ++i) {
+		j = leapcnt;
+		while (--j >= 0)
+			if (ats[i] >= trans[j]) {
+				ats[i] = tadd(ats[i], corr[j]);
+				break;
 			}
-		if (thischarcnt != 0)
-			(void) fwrite((void *) thischars,
-				(size_t) sizeof thischars[0],
-				(size_t) thischarcnt, fp);
-		for (i = thisleapi; i < thisleaplim; ++i) {
-			register zic_t	todo;
-
-			if (roll[i]) {
-				if (timecnt == 0 || trans[i] < ats[0]) {
-					j = 0;
-					while (isdsts[j])
-						if (++j >= typecnt) {
-							j = 0;
-							break;
-						}
-				} else {
-					j = 1;
-					while (j < timecnt &&
-						trans[i] >= ats[j])
-							++j;
-					j = types[j - 1];
-				}
-				todo = tadd(trans[i], -gmtoffs[j]);
-			} else	todo = trans[i];
-			if (pass == 1)
-				puttzcode((long) todo, fp);
-			else	puttzcode64(todo, fp);
-			puttzcode(corr[i], fp);
-		}
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i])
-				(void) putc(ttisstds[i], fp);
-		for (i = 0; i < typecnt; ++i)
-			if (writetype[i])
-				(void) putc(ttisgmts[i], fp);
+		puttzcode((long) ats[i], fp);
 	}
-	(void) fprintf(fp, "\n%s\n", string);
+	if (timecnt > 0)
+		(void) fwrite((void *) types, (size_t) sizeof types[0],
+			(size_t) timecnt, fp);
+	for (i = 0; i < typecnt; ++i) {
+		puttzcode((long) gmtoffs[i], fp);
+		(void) putc(isdsts[i], fp);
+		(void) putc(abbrinds[i], fp);
+	}
+	if (charcnt != 0)
+		(void) fwrite((void *) chars, (size_t) sizeof chars[0],
+			(size_t) charcnt, fp);
+	for (i = 0; i < leapcnt; ++i) {
+		if (roll[i]) {
+			if (timecnt == 0 || trans[i] < ats[0]) {
+				j = 0;
+				while (isdsts[j])
+					if (++j >= typecnt) {
+						j = 0;
+						break;
+					}
+			} else {
+				j = 1;
+				while (j < timecnt && trans[i] >= ats[j])
+					++j;
+				j = types[j - 1];
+			}
+			puttzcode((long) tadd(trans[i], -gmtoffs[j]), fp);
+		} else	puttzcode((long) trans[i], fp);
+		puttzcode((long) corr[i], fp);
+	}
+	for (i = 0; i < typecnt; ++i)
+		(void) putc(ttisstds[i], fp);
+	for (i = 0; i < typecnt; ++i)
+		(void) putc(ttisgmts[i], fp);
 	if (ferror(fp) || fclose(fp)) {
 		(void) fprintf(stderr, _("%s: Error writing %s\n"),
 			progname, fullname);
@@ -1737,223 +1602,21 @@ const char * const	string;
 }
 
 static void
-doabbr(abbr, format, letters, isdst, doquotes)
+doabbr(abbr, format, letters, isdst)
 char * const		abbr;
 const char * const	format;
 const char * const	letters;
 const int		isdst;
-const int		doquotes;
 {
-	register char *	cp;
-	register char *	slashp;
-	register int	len;
-
-	slashp = strchr(format, '/');
-	if (slashp == NULL) {
+	if (strchr(format, '/') == NULL) {
 		if (letters == NULL)
 			(void) strcpy(abbr, format);
 		else	(void) sprintf(abbr, format, letters);
-	} else if (isdst) {
-		(void) strcpy(abbr, slashp + 1);
-	} else {
-		if (slashp > format)
-			(void) strncpy(abbr, format,
-				(unsigned) (slashp - format));
-		abbr[slashp - format] = '\0';
-	}
-	if (!doquotes)
-		return;
-	for (cp = abbr; *cp != '\0'; ++cp)
-		if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ", *cp) == NULL &&
-			strchr("abcdefghijklmnopqrstuvwxyz", *cp) == NULL)
-				break;
-	len = strlen(abbr);
-	if (len > 0 && *cp == '\0')
-		return;
-	abbr[len + 2] = '\0';
-	abbr[len + 1] = '>';
-	for ( ; len > 0; --len)
-		abbr[len] = abbr[len - 1];
-	abbr[0] = '<';
-}
-
-static void
-updateminmax(x)
-const int	x;
-{
-	if (min_year > x)
-		min_year = x;
-	if (max_year < x)
-		max_year = x;
-}
-
-static int
-stringoffset(result, offset)
-char *	result;
-long	offset;
-{
-	register int	hours;
-	register int	minutes;
-	register int	seconds;
-
-	result[0] = '\0';
-	if (offset < 0) {
-		(void) strcpy(result, "-");
-		offset = -offset;
-	}
-	seconds = offset % SECSPERMIN;
-	offset /= SECSPERMIN;
-	minutes = offset % MINSPERHOUR;
-	offset /= MINSPERHOUR;
-	hours = offset;
-	if (hours >= HOURSPERDAY) {
-		result[0] = '\0';
-		return -1;
-	}
-	(void) sprintf(end(result), "%d", hours);
-	if (minutes != 0 || seconds != 0) {
-		(void) sprintf(end(result), ":%02d", minutes);
-		if (seconds != 0)
-			(void) sprintf(end(result), ":%02d", seconds);
-	}
-	return 0;
-}
-
-static int
-stringrule(result, rp, dstoff, gmtoff)
-char *				result;
-const struct rule * const	rp;
-const long			dstoff;
-const long			gmtoff;
-{
-	register long	tod;
-
-	result = end(result);
-	if (rp->r_dycode == DC_DOM) {
-		register int	month, total;
-
-		if (rp->r_dayofmonth == 29 && rp->r_month == TM_FEBRUARY)
-			return -1;
-		total = 0;
-		for (month = 0; month < rp->r_month; ++month)
-			total += len_months[0][month];
-		(void) sprintf(result, "J%d", total + rp->r_dayofmonth);
-	} else {
-		register int	week;
-
-		if (rp->r_dycode == DC_DOWGEQ) {
-			week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
-			if ((week - 1) * DAYSPERWEEK + 1 != rp->r_dayofmonth)
-				return -1;
-		} else if (rp->r_dycode == DC_DOWLEQ) {
-			if (rp->r_dayofmonth == len_months[1][rp->r_month])
-				week = 5;
-			else {
-				week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
-				if (week * DAYSPERWEEK - 1 != rp->r_dayofmonth)
-					return -1;
-			}
-		} else	return -1;	/* "cannot happen" */
-		(void) sprintf(result, "M%d.%d.%d",
-			rp->r_month + 1, week, rp->r_wday);
-	}
-	tod = rp->r_tod;
-	if (rp->r_todisgmt)
-		tod += gmtoff;
-	if (rp->r_todisstd && rp->r_stdoff == 0)
-		tod += dstoff;
-	if (tod < 0) {
-		result[0] = '\0';
-		return -1;
-	}
-	if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
-		(void) strcat(result, "/");
-		if (stringoffset(end(result), tod) != 0)
-			return -1;
-	}
-	return 0;
-}
-
-static void
-stringzone(result, zpfirst, zonecount)
-char *				result;
-const struct zone * const	zpfirst;
-const int			zonecount;
-{
-	register const struct zone *	zp;
-	register struct rule *		rp;
-	register struct rule *		stdrp;
-	register struct rule *		dstrp;
-	register int			i;
-	register const char *		abbrvar;
-
-	result[0] = '\0';
-	zp = zpfirst + zonecount - 1;
-	stdrp = dstrp = NULL;
-	for (i = 0; i < zp->z_nrules; ++i) {
-		rp = &zp->z_rules[i];
-		if (rp->r_hiwasnum || rp->r_hiyear != INT_MAX)
-			continue;
-		if (rp->r_yrtype != NULL)
-			continue;
-		if (rp->r_stdoff == 0) {
-			if (stdrp == NULL)
-				stdrp = rp;
-			else	return;
-		} else {
-			if (dstrp == NULL)
-				dstrp = rp;
-			else	return;
-		}
-	}
-	if (stdrp == NULL && dstrp == NULL) {
-		/*
-		** There are no rules running through "max".
-		** Let's find the latest rule.
-		*/
-		for (i = 0; i < zp->z_nrules; ++i) {
-			rp = &zp->z_rules[i];
-			if (stdrp == NULL || rp->r_hiyear > stdrp->r_hiyear ||
-				(rp->r_hiyear == stdrp->r_hiyear &&
-				rp->r_month > stdrp->r_month))
-					stdrp = rp;
-		}
-		if (stdrp != NULL && stdrp->r_stdoff != 0)
-			return;	/* We end up in DST (a POSIX no-no). */
-		/*
-		** Horrid special case: if year is 2037,
-		** presume this is a zone handled on a year-by-year basis;
-		** do not try to apply a rule to the zone.
-		*/
-		if (stdrp != NULL && stdrp->r_hiyear == 2037)
-			return;
-	}
-	if (stdrp == NULL && zp->z_nrules != 0)
-		return;
-	abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
-	doabbr(result, zp->z_format, abbrvar, FALSE, TRUE);
-	if (stringoffset(end(result), -zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
-	}
-	if (dstrp == NULL)
-		return;
-	doabbr(end(result), zp->z_format, dstrp->r_abbrvar, TRUE, TRUE);
-	if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR)
-		if (stringoffset(end(result),
-			-(zp->z_gmtoff + dstrp->r_stdoff)) != 0) {
-				result[0] = '\0';
-				return;
-		}
-	(void) strcat(result, ",");
-	if (stringrule(result, dstrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
-	}
-	(void) strcat(result, ",");
-	if (stringrule(result, stdrp, dstrp->r_stdoff, zp->z_gmtoff) != 0) {
-		result[0] = '\0';
-		return;
+	} else if (isdst)
+		(void) strcpy(abbr, strchr(format, '/') + 1);
+	else {
+		(void) strcpy(abbr, format);
+		*strchr(abbr, '/') = '\0';
 	}
 }
 
@@ -1974,17 +1637,8 @@ const int			zonecount;
 	register int			startttisstd;
 	register int			startttisgmt;
 	register int			type;
-	register char *			startbuf;
-	register char *			ab;
-	register char *			envvar;
-	register int			max_abbr_len;
-	register int			max_envvar_len;
+	char				startbuf[BUFSIZ];
 
-	max_abbr_len = 2 + max_format_len + max_abbrvar_len;
-	max_envvar_len = 2 * max_abbr_len + 5 * 9;
-	startbuf = emalloc(max_abbr_len + 1);
-	ab = emalloc(max_abbr_len + 1);
-	envvar = emalloc(max_envvar_len + 1);
 	INITIALIZE(untiltime);
 	INITIALIZE(starttime);
 	/*
@@ -1999,48 +1653,6 @@ const int			zonecount;
 	*/
 	startttisstd = FALSE;
 	startttisgmt = FALSE;
-	min_year = max_year = EPOCH_YEAR;
-	if (leapseen) {
-		updateminmax(leapminyear);
-		updateminmax(leapmaxyear);
-	}
-	for (i = 0; i < zonecount; ++i) {
-		zp = &zpfirst[i];
-		updateminmax(zp->z_untilrule.r_loyear);
-		for (j = 0; j < zp->z_nrules; ++j) {
-			rp = &zp->z_rules[j];
-			if (rp->r_lowasnum)
-				updateminmax(rp->r_loyear);
-			if (rp->r_hiwasnum)
-				updateminmax(rp->r_hiyear);
-		}
-	}
-	/*
-	** Generate lots of data if a rule can't cover all future times.
-	*/
-	stringzone(envvar, zpfirst, zonecount);
-	if (noise && envvar[0] == '\0') {
-		register char *	wp;
-
-wp = ecpyalloc(_("no POSIX environment variable for zone"));
-		wp = ecatalloc(wp, " ");
-		wp = ecatalloc(wp, zpfirst->z_name); 
-		warning(wp);
-		ifree(wp);
-	}
-	if (envvar[0] == '\0') {
-		if (min_year >= INT_MIN + YEARSPERREPEAT)
-			min_year -= YEARSPERREPEAT;
-		else	min_year = INT_MIN;
-		if (max_year <= INT_MAX - YEARSPERREPEAT)
-			max_year += YEARSPERREPEAT;
-		else	max_year = INT_MAX;
-	}
-	/*
-	** For the benefit of older systems, generate data through 2037.
-	*/
-	if (max_year < 2037)
-		max_year = 2037;
 	for (i = 0; i < zonecount; ++i) {
 		/*
 		** A guess that may well be corrected later.
@@ -2058,7 +1670,7 @@ wp = ecpyalloc(_("no POSIX environment variable for zone"));
 		if (zp->z_nrules == 0) {
 			stdoff = zp->z_stdoff;
 			doabbr(startbuf, zp->z_format,
-				(char *) NULL, stdoff != 0, FALSE);
+				(char *) NULL, stdoff != 0);
 			type = addtype(oadd(zp->z_gmtoff, stdoff),
 				startbuf, stdoff != 0, startttisstd,
 				startttisgmt);
@@ -2088,6 +1700,7 @@ wp = ecpyalloc(_("no POSIX environment variable for zone"));
 				register int	k;
 				register zic_t	jtime, ktime;
 				register long	offset;
+				char		buf[BUFSIZ];
 
 				INITIALIZE(ktime);
 				if (useuntil) {
@@ -2143,27 +1756,24 @@ wp = ecpyalloc(_("no POSIX environment variable for zone"));
 							stdoff);
 						doabbr(startbuf, zp->z_format,
 							rp->r_abbrvar,
-							rp->r_stdoff != 0,
-							FALSE);
+							rp->r_stdoff != 0);
 						continue;
 					}
 					if (*startbuf == '\0' &&
 						startoff == oadd(zp->z_gmtoff,
-						stdoff)) {
+						stdoff))
 							doabbr(startbuf,
 								zp->z_format,
 								rp->r_abbrvar,
 								rp->r_stdoff !=
-								0,
-								FALSE);
-					}
+								0);
 				}
 				eats(zp->z_filename, zp->z_linenum,
 					rp->r_filename, rp->r_linenum);
-				doabbr(ab, zp->z_format, rp->r_abbrvar,
-					rp->r_stdoff != 0, FALSE);
+				doabbr(buf, zp->z_format, rp->r_abbrvar,
+					rp->r_stdoff != 0);
 				offset = oadd(zp->z_gmtoff, rp->r_stdoff);
-				type = addtype(offset, ab, rp->r_stdoff != 0,
+				type = addtype(offset, buf, rp->r_stdoff != 0,
 					rp->r_todisstd, rp->r_todisgmt);
 				addtt(ktime, type);
 			}
@@ -2196,10 +1806,7 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 				starttime = tadd(starttime, -gmtoff);
 		}
 	}
-	writezone(zpfirst->z_name, envvar);
-	ifree(startbuf);
-	ifree(ab);
-	ifree(envvar);
+	writezone(zpfirst->z_name);
 }
 
 static void
@@ -2578,6 +2185,8 @@ register const int			wantedy;
 will not work with pre-2004 versions of zic"));
 		}
 	}
+	if (dayoff < 0 && !TYPE_SIGNED(zic_t))
+		return min_time;
 	if (dayoff < min_time / SECSPERDAY)
 		return min_time;
 	if (dayoff > max_time / SECSPERDAY)