NetBSD/lib/libc/gen/timezone.c

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/* $NetBSD: timezone.c,v 1.6 1997/01/23 14:01:58 mrg Exp $ */
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/*
* Copyright (c) 1987, 1993
* The Regents of the University of California. All rights reserved.
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*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)timezone.c 8.1 (Berkeley) 6/4/93";
#else
static char rcsid[] = "$NetBSD: timezone.c,v 1.6 1997/01/23 14:01:58 mrg Exp $";
#endif
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#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <tzfile.h>
char *_tztab();
/*
* timezone --
* The arguments are the number of minutes of time you are westward
* from Greenwich and whether DST is in effect. It returns a string
* giving the name of the local timezone. Should be replaced, in the
* application code, by a call to localtime.
*/
static char czone[TZ_MAX_CHARS]; /* space for zone name */
char *
timezone(zone, dst)
int zone,
dst;
{
register char *beg,
*end;
if (beg = getenv("TZNAME")) { /* set in environment */
if (end = strchr(beg, ',')) { /* "PST,PDT" */
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if (dst)
return(++end);
*end = '\0';
(void)strncpy(czone,beg,sizeof(czone) - 1);
czone[sizeof(czone) - 1] = '\0';
*end = ',';
return(czone);
}
return(beg);
}
return(_tztab(zone,dst)); /* default: table or created zone */
}
static struct zone {
int offset;
char *stdzone;
char *dlzone;
} zonetab[] = {
-1*60, "MET", "MET DST", /* Middle European */
-2*60, "EET", "EET DST", /* Eastern European */
4*60, "AST", "ADT", /* Atlantic */
5*60, "EST", "EDT", /* Eastern */
6*60, "CST", "CDT", /* Central */
7*60, "MST", "MDT", /* Mountain */
8*60, "PST", "PDT", /* Pacific */
#ifdef notdef
/* there's no way to distinguish this from WET */
0, "GMT", 0, /* Greenwich */
#endif
0*60, "WET", "WET DST", /* Western European */
-10*60, "EST", "EST", /* Aust: Eastern */
-10*60+30, "CST", "CST", /* Aust: Central */
-8*60, "WST", 0, /* Aust: Western */
-1
};
/*
* _tztab --
* check static tables or create a new zone name; broken out so that
* we can make a guess as to what the zone is if the standard tables
* aren't in place in /etc. DO NOT USE THIS ROUTINE OUTSIDE OF THE
* STANDARD LIBRARY.
*/
char *
_tztab(zone,dst)
register int zone;
int dst;
{
register struct zone *zp;
register char sign;
for (zp = zonetab; zp->offset != -1;++zp) /* static tables */
if (zp->offset == zone) {
if (dst && zp->dlzone)
return(zp->dlzone);
if (!dst && zp->stdzone)
return(zp->stdzone);
}
if (zone < 0) { /* create one */
zone = -zone;
sign = '+';
}
else
sign = '-';
(void)snprintf(czone, TZ_MAX_CHARS, "GMT%c%d:%02d", sign, zone / 60,
zone % 60);
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return(czone);
}