impending tzcode93b.tar.Z

May 24, 1993

      Having received useful changes from several sources, I'm hoping to put up
tzcode93b.tar.Z for anonymous ftp soon.  One thing I'd like to do is
bring "strftime" up to date with new standards (akin to Arnold Robbins'
version).  A proposed "strftime" is attached; grepping for "5/24/93" will
show up where changes have happened.  Any comments would be appreciated;
I'd particularly like word on the matter marked by "XXX" below.

				--ado

#ifndef lint
#ifndef NOID
static char	elsieid[] = "@(#)strftime.c	7.2";
/*
** Based on the UCB version whose ID appears 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 */
/*
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
#endif /* LIBC_SCCS and not lint */

#include "sys/types.h"
#include "time.h"
#include "tzfile.h"

static char *afmt[] = {
	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
};
static char *Afmt[] = {
	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
	"Saturday",
};
static char *bfmt[] = {
	"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
	"Oct", "Nov", "Dec",
};
static char *Bfmt[] = {
	"January", "February", "March", "April", "May", "June", "July",
	"August", "September", "October", "November", "December",
};

static size_t gsize;
static char *pt;

static void _add();
static void _conv();
static void _fmt();

size_t
strftime(s, maxsize, format, t)
	char *s;
	char *format;
	size_t maxsize;
	struct tm *t;
{
	pt = s;
	gsize = maxsize;
	_fmt(format, t);
	if (gsize <= 0)
		return(0);
	*pt = '\0';
	return(maxsize - gsize);
}

static void
_fmt(format, t)
	register char *format;
	struct tm *t;
{
	for (; *format; ++format) {
		if (*format == '%') {
label:
			switch(*++format) {
			case '\0':
				--format;
				break;
			case 'A':
				if (t->tm_wday < 0 || t->tm_wday > 6)
					_add("?");
				else	_add(Afmt[t->tm_wday]);
				continue;
			case 'a':
				if (t->tm_wday < 0 || t->tm_wday > 6)
					_add("?");
				else	_add(afmt[t->tm_wday]);
				continue;
			case 'B':
				if (t->tm_mon < 0 || t->tm_mon > 11)
					_add("?");
				else	_add(Bfmt[t->tm_mon]);
				continue;
			case 'b':
			case 'h':
				if (t->tm_mon < 0 || t->tm_mon > 11)
					_add("?");
				else	_add(bfmt[t->tm_mon]);
				continue;
			case 'c':
				_fmt("%D %X", t);
				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)
				*/
				_conv((t->tm_year + TM_YEAR_BASE) / 100,
					2, '0');
				continue;
			case 'D':
			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.
				** (ado, 5/24/93)
				*/
				_fmt("%m/%d/%y", t);
				continue;
			case 'd':
				_conv(t->tm_mday, 2, '0');
				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':
				_conv(t->tm_mday, 2, ' ');
				continue;
			case 'H':
				_conv(t->tm_hour, 2, '0');
				continue;
			case 'I':
				_conv(t->tm_hour % 12 ?
				    t->tm_hour % 12 : 12, 2, '0');
				continue;
			case 'j':
				_conv(t->tm_yday + 1, 3, '0');
				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)
				*/
				_conv(t->tm_hour, 2, ' ');
				continue;
#ifdef KITCHEN_SINK
			case 'K':
				/*
				** After all this time, still unclaimed!
				*/
				_add("kitchen sink");
				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)
				*/
				_conv(t->tm_hour % 12 ?
					t->tm_hour % 12 : 12, 2, ' ');
				continue;
			case 'M':
				_conv(t->tm_min, 2, '0');
				continue;
			case 'm':
				_conv(t->tm_mon + 1, 2, '0');
				continue;
			case 'n':
				_add("\n");
				continue;
			case 'p':
				_add(t->tm_hour >= 12 ? "PM" : "AM");
				continue;
			case 'R':
				_fmt("%H:%M", t);
				continue;
			case 'r':
				_fmt("%I:%M:%S %p", t);
				continue;
			case 'S':
				_conv(t->tm_sec, 2, '0');
				continue;
			case 'T':
			case 'X':
				_fmt("%H:%M:%S", t);
				continue;
			case 't':
				_add("\t");
				continue;
			case 'U':
				_conv((t->tm_yday + 7 - t->tm_wday) / 7,
					2, '0');
				continue;
			case 'u':
				/*
				** From Arnold Robbins' strftime version 3.0:
				** "ISO 8601: Weekday as a decimal number
				** [1 (Monday) - 7]"
				** (ado, 5/24/93)
				*/
				_conv(((t->tm_wday == 0) ? 7 : t->tm_wday),
					1, '0');
				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.
				*/
				{
					register int	i;

					i = (t->tm_yday + 10 - (t->tm_wday ?
						(t->tm_wday - 1) : 6)) / 7;
					_conv((i == 0) ? 53 : i, 2, '0');
				}
				continue;
			case 'v':
				/*
				** From Arnold Robbins' strftime version 3.0:
				** "date as dd-bbb-YYYY"
				** (ado, 5/24/93)
				*/
				_fmt("%e-%b-%Y");
				continue;
			case 'W':
				_conv((t->tm_yday + 7 -
				    (t->tm_wday ? (t->tm_wday - 1) : 6))
				    / 7, 2, '0');
				continue;
			case 'w':
				_conv(t->tm_wday, 1, '0');
				continue;
			case 'y':
				_conv((t->tm_year + TM_YEAR_BASE) % 100,
					2, '0');
				continue;
			case 'Y':
				_conv(t->tm_year + TM_YEAR_BASE, 4, '0');
				continue;
			case 'Z':
#ifdef TM_ZONE
				if (t->TM_ZONE)
					_add(t->TM_ZONE);
				else
#endif /* defined TM_ZONE */
				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
					extern char *	tzname[2];

					_add(tzname[t->tm_isdst]);
				} else	_add("?");
				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 (gsize <= 0)
			return;
		*pt++ = *format;
		--gsize;
	}
}

static void
_conv(n, digits, fill)
	int n, digits, fill;
{
	static char buf[10];
	register char *p;

	for (p = buf + sizeof(buf) - 2; n > 0 && p > buf; n /= 10, --digits)
		*p-- = n % 10 + '0';
	while (p > buf && digits-- > 0)
		*p-- = fill;
	_add(++p);
}

static void
_add(str)
	register char *str;
{
	for (;; ++pt, --gsize) {
		if (gsize <= 0)
			return;
		if (!(*pt = *str++))
			return;
	}
}