The rest of tzcode94g from Arthur David Olson.

Obtained From: Arthur David Olson, ftp://elsie.nci.nih.gov/pub/tzcode94g.tar.gz

lib/libc/stdtime/asctime.c

@@ -0,0 +1,56 @@
+#ifndef lint
+#ifndef NOID
+static char	elsieid[] = "@(#)asctime.c	7.5";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*LINTLIBRARY*/
+
+#include "private.h"
+#include "tzfile.h"
+
+/*
+** A la X3J11, with core dump avoidance.
+*/
+
+char *
+asctime(timeptr)
+register const struct tm *	timeptr;
+{
+	static const char	wday_name[][3] = {
+		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+	};
+	static const char	mon_name[][3] = {
+		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+	};
+	/*
+	** Big enough for something such as
+	** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
+	** (two three-character abbreviations, five strings denoting integers,
+	** three explicit spaces, two explicit colons, a newline,
+	** and a trailing ASCII nul).
+	*/
+	static char		result[3 * 2 + 5 * INT_STRLEN_MAXIMUM(int) +
+					3 + 2 + 1 + 1];
+	register const char *	wn;
+	register const char *	mn;
+
+	if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
+		wn = "???";
+	else	wn = wday_name[timeptr->tm_wday];
+	if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
+		mn = "???";
+	else	mn = mon_name[timeptr->tm_mon];
+	/*
+	** The X3J11-suggested format is
+	**	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d %d\n"
+	** Since the .2 in 02.2d is ignored, we drop it.
+	*/
+	(void) sprintf(result, "%.3s %.3s%3d %02d:%02d:%02d %d\n",
+		wn, mn,
+		timeptr->tm_mday, timeptr->tm_hour,
+		timeptr->tm_min, timeptr->tm_sec,
+		TM_YEAR_BASE + timeptr->tm_year);
+	return result;
+}

lib/libc/stdtime/difftime.c

@@ -0,0 +1,74 @@
+#ifndef lint
+#ifndef NOID
+static char	elsieid[] = "@(#)difftime.c	7.4";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*LINTLIBRARY*/
+
+#include "private.h"
+
+/*
+** Algorithm courtesy Paul Eggert (eggert@twinsun.com).
+*/
+
+#ifdef HAVE_LONG_DOUBLE
+#define long_double	long double
+#endif /* defined HAVE_LONG_DOUBLE */
+#ifndef HAVE_LONG_DOUBLE
+#define long_double	double
+#endif /* !defined HAVE_LONG_DOUBLE */
+
+double
+difftime(time1, time0)
+const time_t	time1;
+const time_t	time0;
+{
+	time_t	delta;
+	time_t	hibit;
+
+	if (sizeof(time_t) < sizeof(double))
+		return (double) time1 - (double) time0;
+	if (sizeof(time_t) < sizeof(long_double))
+		return (long_double) time1 - (long_double) time0;
+	if (time1 < time0)
+		return -difftime(time0, time1);
+	/*
+	** As much as possible, avoid loss of precision
+	** by computing the difference before converting to double.
+	*/
+	delta = time1 - time0;
+	if (delta >= 0)
+		return delta;
+	/*
+	** Repair delta overflow.
+	*/
+	hibit = 1;
+	while ((hibit <<= 1) > 0)
+		continue;
+	/*
+	** The following expression rounds twice, which means
+	** the result may not be the closest to the true answer.
+	** For example, suppose time_t is 64-bit signed int,
+	** long_double is IEEE 754 double with default rounding,
+	** time1 = 9223372036854775807 and time0 = -1536.
+	** Then the true difference is 9223372036854777343,
+	** which rounds to 9223372036854777856
+	** with a total error of 513.
+	** But delta overflows to -9223372036854774273,
+	** which rounds to -9223372036854774784, and correcting
+	** this by subtracting 2 * (long_double) hibit
+	** (i.e. by adding 2**64 = 18446744073709551616)
+	** yields 9223372036854776832, which
+	** rounds to 9223372036854775808
+	** with a total error of 1535 instead.
+	** This problem occurs only with very large differences.
+	** It's too painful to fix this portably.
+	** We are not alone in this problem;
+	** many C compilers round twice when converting
+	** large unsigned types to small floating types,
+	** so if time_t is unsigned the "return delta" above
+	** has the same double-rounding problem.
+	*/
+	return delta - 2 * (long_double) hibit;
+}

lib/libc/stdtime/private.h

@@ -0,0 +1,185 @@
+#ifndef PRIVATE_H
+
+#define PRIVATE_H
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** ID
+*/
+
+#ifndef lint
+#ifndef NOID
+static char	privatehid[] = "@(#)private.h	7.5";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*
+** const
+*/
+
+#ifndef const
+#ifndef __STDC__
+#define const
+#endif /* !defined __STDC__ */
+#endif /* !defined const */
+
+/*
+** void
+*/
+
+#ifndef void
+#ifndef __STDC__
+#ifndef vax
+#ifndef sun
+#define void	char
+#endif /* !defined sun */
+#endif /* !defined vax */
+#endif /* !defined __STDC__ */
+#endif /* !defined void */
+
+/*
+** P((args))
+*/
+
+#ifndef P
+#ifdef __STDC__
+#define P(x)	x
+#endif /* defined __STDC__ */
+#ifndef __STDC__
+#define ASTERISK	*
+#define P(x)	( /ASTERISK x ASTERISK/ )
+#endif /* !defined __STDC__ */
+#endif /* !defined P */
+
+/*
+** genericptr_t
+*/
+
+#ifdef __STDC__
+typedef void *		genericptr_t;
+#endif /* defined __STDC__ */
+#ifndef __STDC__
+typedef char *		genericptr_t;
+#endif /* !defined __STDC__ */
+
+#include "sys/types.h"	/* for time_t */
+#include "stdio.h"
+#include "ctype.h"
+#include "errno.h"
+#include "string.h"
+#include "limits.h"	/* for CHAR_BIT */
+#ifndef _TIME_
+#include "time.h"
+#endif /* !defined _TIME_ */
+
+#ifndef remove
+extern int	unlink P((const char * filename));
+#define remove	unlink
+#endif /* !defined remove */
+
+#ifndef FILENAME_MAX
+
+#ifndef MAXPATHLEN
+#ifdef unix
+#include "sys/param.h"
+#endif /* defined unix */
+#endif /* !defined MAXPATHLEN */
+
+#ifdef MAXPATHLEN
+#define FILENAME_MAX	MAXPATHLEN
+#endif /* defined MAXPATHLEN */
+#ifndef MAXPATHLEN
+#define FILENAME_MAX	1024		/* Pure guesswork */
+#endif /* !defined MAXPATHLEN */
+
+#endif /* !defined FILENAME_MAX */
+
+#ifndef EXIT_SUCCESS
+#define EXIT_SUCCESS	0
+#endif /* !defined EXIT_SUCCESS */
+
+#ifndef EXIT_FAILURE
+#define EXIT_FAILURE	1
+#endif /* !defined EXIT_FAILURE */
+
+#ifdef __STDC__
+
+#define alloc_size_t	size_t
+#define qsort_size_t	size_t
+#define fwrite_size_t	size_t
+
+#endif /* defined __STDC__ */
+#ifndef __STDC__
+
+#ifndef alloc_size_t
+#define alloc_size_t	unsigned
+#endif /* !defined alloc_size_t */
+
+#ifndef qsort_size_t
+#ifdef USG
+#define qsort_size_t	unsigned
+#endif /* defined USG */
+#ifndef USG
+#define qsort_size_t	int
+#endif /* !defined USG */
+#endif /* !defined qsort_size_t */
+
+#ifndef fwrite_size_t
+#define fwrite_size_t	int
+#endif /* !defined fwrite_size_t */
+
+#ifndef USG
+extern char *		sprintf P((char * buf, const char * format, ...));
+#endif /* !defined USG */
+
+#endif /* !defined __STDC__ */
+
+/*
+** Ensure that these are declared--redundantly declaring them shouldn't hurt.
+*/
+
+extern char *		getenv P((const char * name));
+extern genericptr_t	malloc P((alloc_size_t size));
+extern genericptr_t	calloc P((alloc_size_t nelem, alloc_size_t elsize));
+extern genericptr_t	realloc P((genericptr_t oldptr, alloc_size_t newsize));
+
+#ifdef USG
+extern void		exit P((int s));
+extern void		qsort P((genericptr_t base, qsort_size_t nelem,
+				qsort_size_t elsize, int (*comp)()));
+extern void		perror P((const char * string));
+extern void		free P((char * buf));
+#endif /* defined USG */
+
+#ifndef TRUE
+#define TRUE	1
+#endif /* !defined TRUE */
+
+#ifndef FALSE
+#define FALSE	0
+#endif /* !defined FALSE */
+
+#ifndef INT_STRLEN_MAXIMUM
+/*
+** 302 / 1000 is log10(2.0) rounded up.
+** Subtract one for the sign bit;
+** add one for integer division truncation;
+** add one more for a minus sign.
+*/
+#define INT_STRLEN_MAXIMUM(type) \
+	((sizeof(type) * CHAR_BIT - 1) * 302 / 1000 + 2)
+#endif /* !defined INT_STRLEN_MAXIMUM */
+
+/*
+** UNIX is a registered trademark of AT&T.
+** VAX is a trademark of Digital Equipment Corporation.
+*/
+
+#endif /* !defined PRIVATE_H */

lib/libc/stdtime/strftime.c

@@ -0,0 +1,393 @@
+#ifndef lint
+#ifndef NOID
+static char	elsieid[] = "@(#)strftime.c	7.19";
+/*
+** Based on the UCB version with the ID appearing below.
+** This is ANSIish only when time is treated identically in all locales and
+** when "multibyte character == plain character".
+*/
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+#include "private.h"
+
+/*
+ * Copyright (c) 1989 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, Berkeley.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#ifndef LIBC_SCCS
+#ifndef lint
+static const char sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
+#endif /* !defined lint */
+#endif /* !defined LIBC_SCCS */
+
+#include "tzfile.h"
+
+static const char afmt[][4] = {
+	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+static const char Afmt[][10] = {
+	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
+	"Saturday"
+};
+static const char bfmt[][4] = {
+	"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
+	"Oct", "Nov", "Dec"
+};
+static const char Bfmt[][10] = {
+	"January", "February", "March", "April", "May", "June", "July",
+	"August", "September", "October", "November", "December"
+};
+
+static char *_add P((const char *, char *, const char *));
+static char *_conv P((int, const char *, char *, const char *));
+static char *_fmt P((const char *, const struct tm *, char *, const char *));
+
+size_t strftime P((char *, size_t, const char *, const struct tm *));
+
+extern char *tzname[];
+
+size_t
+strftime(s, maxsize, format, t)
+	char *s;
+	size_t maxsize;
+	const char *format;
+	const struct tm *t;
+{
+	char *p;
+
+	p = _fmt(format, t, s, s + maxsize);
+	if (p == s + maxsize)
+		return 0;
+	*p = '\0';
+	return p - s;
+}
+
+static char *
+_fmt(format, t, pt, ptlim)
+	const char *format;
+	const struct tm *t;
+	char *pt;
+	const char *ptlim;
+{
+	for (; *format; ++format) {
+		if (*format == '%') {
+label:
+			switch(*++format) {
+			case '\0':
+				--format;
+				break;
+			case 'A':
+				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
+					"?" : Afmt[t->tm_wday], pt, ptlim);
+				continue;
+			case 'a':
+				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
+					"?" : afmt[t->tm_wday], pt, ptlim);
+				continue;
+			case 'B':
+				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
+					"?" : Bfmt[t->tm_mon], pt, ptlim);
+				continue;
+			case 'b':
+			case 'h':
+				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
+					"?" : bfmt[t->tm_mon], pt, ptlim);
+				continue;
+			case 'c':
+				pt = _fmt("%D %X", t, pt, ptlim);
+				continue;
+			case 'C':
+				/*
+				** %C used to do a...
+				**	_fmt("%a %b %e %X %Y", t);
+				** ...whereas now POSIX 1003.2 calls for
+				** something completely different.
+				** (ado, 5/24/93)
+				*/
+				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
+					"%02d", pt, ptlim);
+				continue;
+			case 'D':
+				pt = _fmt("%m/%d/%y", t, pt, ptlim);
+				continue;
+			case 'x':
+				/*
+				** Version 3.0 of strftime from Arnold Robbins
+				** (arnold@skeeve.atl.ga.us) does the
+				** equivalent of...
+				**	_fmt("%a %b %e %Y");
+				** ...for %x; since the X3J11 C language
+				** standard calls for "date, using locale's
+				** date format," anything goes.  Using just
+				** numbers (as here) makes Quakers happier.
+				** Word from Paul Eggert (eggert@twinsun.com)
+				** is that %Y-%m-%d is the ISO standard date
+				** format, specified in ISO 2014 and later
+				** ISO 8601:1988, with a summary available in
+				** pub/doc/ISO/english/ISO8601.ps.Z on
+				** ftp.uni-erlangen.de.
+				** (ado, 5/30/93)
+				*/
+				pt = _fmt("%m/%d/%y", t, pt, ptlim);
+				continue;
+			case 'd':
+				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
+				continue;
+			case 'E':
+			case 'O':
+				/*
+				** POSIX locale extensions, a la
+				** Arnold Robbins' strftime version 3.0.
+				** The sequences
+				**	%Ec %EC %Ex %Ey %EY
+				**	%Od %oe %OH %OI %Om %OM
+				**	%OS %Ou %OU %OV %Ow %OW %Oy
+				** are supposed to provide alternate
+				** representations.
+				** (ado, 5/24/93)
+				*/
+				goto label;
+			case 'e':
+				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
+				continue;
+			case 'H':
+				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
+				continue;
+			case 'I':
+				pt = _conv((t->tm_hour % 12) ?
+					(t->tm_hour % 12) : 12,
+					"%02d", pt, ptlim);
+				continue;
+			case 'j':
+				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
+				continue;
+			case 'k':
+				/*
+				** This used to be...
+				**	_conv(t->tm_hour % 12 ?
+				**		t->tm_hour % 12 : 12, 2, ' ');
+				** ...and has been changed to the below to
+				** match SunOS 4.1.1 and Arnold Robbins'
+				** strftime version 3.0.  That is, "%k" and
+				** "%l" have been swapped.
+				** (ado, 5/24/93)
+				*/
+				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
+				continue;
+#ifdef KITCHEN_SINK
+			case 'K':
+				/*
+				** After all this time, still unclaimed!
+				*/
+				pt = _add("kitchen sink", pt, ptlim);
+				continue;
+#endif /* defined KITCHEN_SINK */
+			case 'l':
+				/*
+				** This used to be...
+				**	_conv(t->tm_hour, 2, ' ');
+				** ...and has been changed to the below to
+				** match SunOS 4.1.1 and Arnold Robbin's
+				** strftime version 3.0.  That is, "%k" and
+				** "%l" have been swapped.
+				** (ado, 5/24/93)
+				*/
+				pt = _conv((t->tm_hour % 12) ?
+					(t->tm_hour % 12) : 12,
+					"%2d", pt, ptlim);
+				continue;
+			case 'M':
+				pt = _conv(t->tm_min, "%02d", pt, ptlim);
+				continue;
+			case 'm':
+				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
+				continue;
+			case 'n':
+				pt = _add("\n", pt, ptlim);
+				continue;
+			case 'p':
+				pt = _add(t->tm_hour >= 12 ? "PM" : "AM",
+					pt, ptlim);
+				continue;
+			case 'R':
+				pt = _fmt("%H:%M", t, pt, ptlim);
+				continue;
+			case 'r':
+				pt = _fmt("%I:%M:%S %p", t, pt, ptlim);
+				continue;
+			case 'S':
+				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
+				continue;
+			case 'T':
+			case 'X':
+				pt = _fmt("%H:%M:%S", t, pt, ptlim);
+				continue;
+			case 't':
+				pt = _add("\t", pt, ptlim);
+				continue;
+			case 'U':
+				pt = _conv((t->tm_yday + 7 - t->tm_wday) / 7,
+					"%02d", pt, ptlim);
+				continue;
+			case 'u':
+				/*
+				** From Arnold Robbins' strftime version 3.0:
+				** "ISO 8601: Weekday as a decimal number
+				** [1 (Monday) - 7]"
+				** (ado, 5/24/93)
+				*/
+				pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday,
+					"%d", pt, ptlim);
+				continue;
+			case 'V':
+				/*
+				** From Arnold Robbins' strftime version 3.0:
+				** "the week number of the year (the first
+				** Monday as the first day of week 1) as a
+				** decimal number (01-53).  The method for
+				** determining the week number is as specified
+				** by ISO 8601 (to wit: if the week containing
+				** January 1 has four or more days in the new
+				** year, then it is week 1, otherwise it is
+				** week 53 of the previous year and the next
+				** week is week 1)."
+				** (ado, 5/24/93)
+				*/
+				/*
+				** XXX--If January 1 falls on a Friday,
+				** January 1-3 are part of week 53 of the
+				** previous year.  By analogy, if January
+				** 1 falls on a Thursday, are December 29-31
+				** of the PREVIOUS year part of week 1???
+				** (ado 5/24/93)
+				**
+				** You are understood not to expect this.
+				*/
+				{
+					int i;
+
+					i = (t->tm_yday + 10 - (t->tm_wday ?
+						(t->tm_wday - 1) : 6)) / 7;
+					if (i == 0) {
+						/*
+						** What day of the week does
+						** January 1 fall on?
+						*/
+						i = t->tm_wday -
+							(t->tm_yday - 1);
+						/*
+						** Fri Jan 1: 53
+						** Sun Jan 1: 52
+						** Sat Jan 1: 53 if previous
+						** 		 year a leap
+						**		 year, else 52
+						*/
+						if (i == TM_FRIDAY)
+							i = 53;
+						else if (i == TM_SUNDAY)
+							i = 52;
+						else	i = isleap(t->tm_year +
+								TM_YEAR_BASE) ?
+								53 : 52;
+#ifdef XPG4_1994_04_09
+						/*
+						** As of 4/9/94, though,
+						** XPG4 calls for 53
+						** unconditionally.
+						*/
+						i = 53;
+#endif /* defined XPG4_1994_04_09 */
+					}
+					pt = _conv(i, "%02d", pt, ptlim);
+				}
+				continue;
+			case 'v':
+				/*
+				** From Arnold Robbins' strftime version 3.0:
+				** "date as dd-bbb-YYYY"
+				** (ado, 5/24/93)
+				*/
+				pt = _fmt("%e-%b-%Y", t, pt, ptlim);
+				continue;
+			case 'W':
+				pt = _conv((t->tm_yday + 7 -
+					(t->tm_wday ?
+					(t->tm_wday - 1) : 6)) / 7,
+					"%02d", pt, ptlim);
+				continue;
+			case 'w':
+				pt = _conv(t->tm_wday, "%d", pt, ptlim);
+				continue;
+			case 'y':
+				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
+					"%02d", pt, ptlim);
+				continue;
+			case 'Y':
+				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
+					pt, ptlim);
+				continue;
+			case 'Z':
+#ifdef TM_ZONE
+				if (t->TM_ZONE)
+					pt = _add(t->TM_ZONE, pt, ptlim);
+				else
+#endif /* defined TM_ZONE */
+				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
+					pt = _add(tzname[t->tm_isdst],
+						pt, ptlim);
+				} else  pt = _add("?", pt, ptlim);
+				continue;
+			case '%':
+			/*
+			 * X311J/88-090 (4.12.3.5): if conversion char is
+			 * undefined, behavior is undefined.  Print out the
+			 * character itself as printf(3) also does.
+			 */
+			default:
+				break;
+			}
+		}
+		if (pt == ptlim)
+			break;
+		*pt++ = *format;
+	}
+	return pt;
+}
+
+static char *
+_conv(n, format, pt, ptlim)
+	int n;
+	const char *format;
+	char *pt;
+	const char *ptlim;
+{
+	char buf[INT_STRLEN_MAXIMUM(int) + 1];
+
+	(void) sprintf(buf, format, n);
+	return _add(buf, pt, ptlim);
+}
+
+static char *
+_add(str, pt, ptlim)
+	const char *str;
+	char *pt;
+	const char *ptlim;
+{
+	while (pt < ptlim && (*pt = *str++) != '\0')
+		++pt;
+	return pt;
+}

lib/libc/stdtime/time2posix.3

@@ -0,0 +1,119 @@
+.TH TIME2POSIX 3
+.SH NAME
+time2posix, posix2time \- convert seconds since the Epoch
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <time.h>
+.PP
+.B time_t time2posix(t)
+.B time_t t
+.PP
+.B time_t posix2time(t)
+.B time_t t
+.PP
+.B cc ... -lz
+.fi
+.SH DESCRIPTION
+IEEE Standard 1003.1
+(POSIX)
+legislates that a time_t value of
+536457599 shall correspond to "Wed Dec 31 23:59:59 GMT 1986."
+This effectively implies that POSIX time_t's cannot include leap
+seconds and,
+therefore,
+that the system time must be adjusted as each leap occurs.
+.PP
+If the time package is configured with leap-second support
+enabled,
+however,
+no such adjustment is needed and
+time_t values continue to increase over leap events
+(as a true `seconds since...' value).
+This means that these values will differ from those required by POSIX
+by the net number of leap seconds inserted since the Epoch.
+.PP
+Typically this is not a problem as the type time_t is intended
+to be
+(mostly)
+opaque\(emtime_t values should only be obtained-from and
+passed-to functions such as
+.IR time(2) ,
+.IR localtime(3) ,
+.IR mktime(3) ,
+and
+.IR difftime(3) .
+However,
+POSIX gives an arithmetic
+expression for directly computing a time_t value from a given date/time,
+and the same relationship is assumed by some
+(usually older)
+applications.
+Any programs creating/dissecting time_t's
+using such a relationship will typically not handle intervals
+over leap seconds correctly.
+.PP
+The
+.I time2posix
+and
+.I posix2time
+functions are provided to address this time_t mismatch by converting
+between local time_t values and their POSIX equivalents.
+This is done by accounting for the number of time-base changes that
+would have taken place on a POSIX system as leap seconds were inserted
+or deleted.
+These converted values can then be used in lieu of correcting the older
+applications,
+or when communicating with POSIX-compliant systems.
+.PP
+.I Time2posix
+is single-valued.
+That is,
+every local time_t
+corresponds to a single POSIX time_t.
+.I Posix2time
+is less well-behaved:
+for a positive leap second hit the result is not unique,
+and for a negative leap second hit the corresponding
+POSIX time_t doesn't exist so an adjacent value is returned.
+Both of these are good indicators of the inferiority of the
+POSIX representation.
+.PP
+The following table summarizes the relationship between a time
+T and it's conversion to,
+and back from,
+the POSIX representation over the leap second inserted at the end of June,
+1993.
+.nf
+.ta \w'93/06/30 'u +\w'23:59:59 'u +\w'A+0 'u +\w'X=time2posix(T) 'u
+DATE	TIME	T	X=time2posix(T)	posix2time(X)
+93/06/30	23:59:59	A+0	B+0	A+0
+93/06/30	23:59:60	A+1	B+1	A+1 or A+2
+93/07/01	00:00:00	A+2	B+1	A+1 or A+2
+93/07/01	00:00:01	A+3	B+2	A+3
+
+A leap second deletion would look like...
+
+DATE	TIME	T	X=time2posix(T)	posix2time(X)
+??/06/30	23:59:58	A+0	B+0	A+0
+??/07/01	00:00:00	A+1	B+2	A+1
+??/07/01	00:00:01	A+2	B+3	A+2
+.sp
+.ce
+	[Note: posix2time(B+1) => A+0 or A+1]
+.fi
+.PP
+If leap-second support is not enabled,
+local time_t's and
+POSIX time_t's are equivalent,
+and both
+.I time2posix
+and
+.I posix2time
+degenerate to the identity function.
+.SH SEE ALSO
+difftime(3),
+localtime(3),
+mktime(3),
+time(2)
+.\" @(#)time2posix.3	7.3

lib/libc/stdtime/tzfile.5

@@ -0,0 +1,123 @@
+.TH TZFILE 5
+.SH NAME
+tzfile \- time zone information
+.SH SYNOPSIS
+.B
+#include <tzfile.h>
+.SH DESCRIPTION
+The time zone information files used by
+.IR tzset (3)
+begin with bytes reserved for future use,
+followed by four four-byte values of type
+.BR long ,
+written in a ``standard'' byte order
+(the high-order byte of the value is written first).
+These values are,
+in order:
+.TP
+.I tzh_ttisstdcnt
+The number of standard/wall indicators stored in the file.
+.TP
+.I tzh_leapcnt
+The number of leap seconds for which data is stored in the file.
+.TP
+.I tzh_timecnt
+The number of "transition times" for which data is stored
+in the file.
+.TP
+.I tzh_typecnt
+The number of "local time types" for which data is stored
+in the file (must not be zero).
+.TP
+.I tzh_charcnt
+The number of characters of "time zone abbreviation strings"
+stored in the file.
+.PP
+The above header is followed by
+.I tzh_timecnt
+four-byte values of type
+.BR long ,
+sorted in ascending order.
+These values are written in ``standard'' byte order.
+Each is used as a transition time (as returned by
+.IR time (2))
+at which the rules for computing local time change.
+Next come
+.I tzh_timecnt
+one-byte values of type
+.BR "unsigned char" ;
+each one tells which of the different types of ``local time'' types
+described in the file is associated with the same-indexed transition time.
+These values serve as indices into an array of
+.I ttinfo
+structures that appears next in the file;
+these structures are defined as follows:
+.in +.5i
+.sp
+.nf
+.ta .5i +\w'unsigned int\0\0'u
+struct ttinfo {
+	long	tt_gmtoff;
+	int	tt_isdst;
+	unsigned int	tt_abbrind;
+};
+.in -.5i
+.fi
+.sp
+Each structure is written as a four-byte value for
+.I tt_gmtoff
+of type
+.BR long ,
+in a standard byte order, followed by a one-byte value for
+.I tt_isdst
+and a one-byte value for
+.IR tt_abbrind .
+In each structure,
+.I tt_gmtoff
+gives the number of seconds to be added to GMT,
+.I tt_isdst
+tells whether
+.I tm_isdst
+should be set by
+.I localtime (3)
+and
+.I tt_abbrind
+serves as an index into the array of time zone abbreviation characters
+that follow the
+.I ttinfo
+structure(s) in the file.
+.PP
+Then there are
+.I tzh_leapcnt
+pairs of four-byte values, written in standard byte order;
+the first value of each pair gives the time
+(as returned by
+.IR time(2))
+at which a leap second occurs;
+the second gives the
+.I total
+number of leap seconds to be applied after the given time.
+The pairs of values are sorted in ascending order by time.
+.PP
+Finally there are
+.I tzh_ttisstdcnt
+standard/wall indicators, each stored as a one-byte value;
+they tell whether the transition times associated with local time types
+were specified as standard time or wall clock time,
+and are used when a time zone file is used in handling POSIX-style
+time zone environment variables.
+.PP
+.I Localtime
+uses the first standard-time
+.I ttinfo
+structure in the file
+(or simply the first
+.I ttinfo
+structure in the absence of a standard-time structure)
+if either
+.I tzh_timecnt
+is zero or the time argument is less than the first transition time recorded
+in the file.
+.SH SEE ALSO
+newctime(3)
+.\" @(#)tzfile.5	7.2

lib/libc/stdtime/tzfile.h

@@ -0,0 +1,170 @@
+#ifndef TZFILE_H
+
+#define TZFILE_H
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** ID
+*/
+
+#ifndef lint
+#ifndef NOID
+static char	tzfilehid[] = "@(#)tzfile.h	7.4";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*
+** Information about time zone files.
+*/
+
+#ifndef TZDIR
+#define TZDIR	"/usr/local/etc/zoneinfo" /* Time zone object file directory */
+#endif /* !defined TZDIR */
+
+#ifndef TZDEFAULT
+#define TZDEFAULT	"localtime"
+#endif /* !defined TZDEFAULT */
+
+#ifndef TZDEFRULES
+#define TZDEFRULES	"posixrules"
+#endif /* !defined TZDEFRULES */
+
+/*
+** Each file begins with. . .
+*/
+
+struct tzhead {
+	char	tzh_reserved[24];	/* reserved for future use */
+	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
+	char	tzh_leapcnt[4];		/* coded number of leap seconds */
+	char	tzh_timecnt[4];		/* coded number of transition times */
+	char	tzh_typecnt[4];		/* coded number of local time types */
+	char	tzh_charcnt[4];		/* coded number of abbr. chars */
+};
+
+/*
+** . . .followed by. . .
+**
+**	tzh_timecnt (char [4])s		coded transition times a la time(2)
+**	tzh_timecnt (unsigned char)s	types of local time starting at above
+**	tzh_typecnt repetitions of
+**		one (char [4])		coded GMT offset in seconds
+**		one (unsigned char)	used to set tm_isdst
+**		one (unsigned char)	that's an abbreviation list index
+**	tzh_charcnt (char)s		'\0'-terminated zone abbreviations
+**	tzh_leapcnt repetitions of
+**		one (char [4])		coded leap second transition times
+**		one (char [4])		total correction after above
+**	tzh_ttisstdcnt (char)s		indexed by type; if TRUE, transition
+**					time is standard time, if FALSE,
+**					transition time is wall clock time
+**					if absent, transition times are
+**					assumed to be wall clock time
+*/
+
+/*
+** In the current implementation, "tzset()" refuses to deal with files that
+** exceed any of the limits below.
+*/
+
+#ifndef TZ_MAX_TIMES
+/*
+** The TZ_MAX_TIMES value below is enough to handle a bit more than a
+** year's worth of solar time (corrected daily to the nearest second) or
+** 138 years of Pacific Presidential Election time
+** (where there are three time zone transitions every fourth year).
+*/
+#define TZ_MAX_TIMES	370
+#endif /* !defined TZ_MAX_TIMES */
+
+#ifndef TZ_MAX_TYPES
+#ifndef NOSOLAR
+#define TZ_MAX_TYPES	256 /* Limited by what (unsigned char)'s can hold */
+#endif /* !defined NOSOLAR */
+#ifdef NOSOLAR
+#define TZ_MAX_TYPES	10	/* Maximum number of local time types */
+#endif /* !defined NOSOLAR */
+#endif /* !defined TZ_MAX_TYPES */
+
+#ifndef TZ_MAX_CHARS
+#define TZ_MAX_CHARS	50	/* Maximum number of abbreviation characters */
+				/* (limited by what unsigned chars can hold) */
+#endif /* !defined TZ_MAX_CHARS */
+
+#ifndef TZ_MAX_LEAPS
+#define TZ_MAX_LEAPS	50	/* Maximum number of leap second corrections */
+#endif /* !defined TZ_MAX_LEAPS */
+
+#define SECSPERMIN	60
+#define MINSPERHOUR	60
+#define HOURSPERDAY	24
+#define DAYSPERWEEK	7
+#define DAYSPERNYEAR	365
+#define DAYSPERLYEAR	366
+#define SECSPERHOUR	(SECSPERMIN * MINSPERHOUR)
+#define SECSPERDAY	((long) SECSPERHOUR * HOURSPERDAY)
+#define MONSPERYEAR	12
+
+#define TM_SUNDAY	0
+#define TM_MONDAY	1
+#define TM_TUESDAY	2
+#define TM_WEDNESDAY	3
+#define TM_THURSDAY	4
+#define TM_FRIDAY	5
+#define TM_SATURDAY	6
+
+#define TM_JANUARY	0
+#define TM_FEBRUARY	1
+#define TM_MARCH	2
+#define TM_APRIL	3
+#define TM_MAY		4
+#define TM_JUNE		5
+#define TM_JULY		6
+#define TM_AUGUST	7
+#define TM_SEPTEMBER	8
+#define TM_OCTOBER	9
+#define TM_NOVEMBER	10
+#define TM_DECEMBER	11
+
+#define TM_YEAR_BASE	1900
+
+#define EPOCH_YEAR	1970
+#define EPOCH_WDAY	TM_THURSDAY
+
+/*
+** Accurate only for the past couple of centuries;
+** that will probably do.
+*/
+
+#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
+
+#ifndef USG
+
+/*
+** Use of the underscored variants may cause problems if you move your code to
+** certain System-V-based systems; for maximum portability, use the
+** underscore-free variants.  The underscored variants are provided for
+** backward compatibility only; they may disappear from future versions of
+** this file.
+*/
+
+#define SECS_PER_MIN	SECSPERMIN
+#define MINS_PER_HOUR	MINSPERHOUR
+#define HOURS_PER_DAY	HOURSPERDAY
+#define DAYS_PER_WEEK	DAYSPERWEEK
+#define DAYS_PER_NYEAR	DAYSPERNYEAR
+#define DAYS_PER_LYEAR	DAYSPERLYEAR
+#define SECS_PER_HOUR	SECSPERHOUR
+#define SECS_PER_DAY	SECSPERDAY
+#define MONS_PER_YEAR	MONSPERYEAR
+
+#endif /* !defined USG */
+
+#endif /* !defined TZFILE_H */