freebsd-dev/lib/libc/gen/timezone.c

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/*
* Copyright (c) 1987, 1993
* The Regents of the University of California. All rights reserved.
*
* 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)
static char sccsid[] = "@(#)timezone.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
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#include <sys/types.h>
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TZ_MAX_CHARS 255
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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;
{
char *beg,
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*end;
if ( (beg = getenv("TZNAME")) ) { /* set in environment */
if ( (end = index(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 */
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#ifdef notdef
/* there's no way to distinguish this from WET */
{0, "GMT", 0}, /* Greenwich */
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#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}
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};
/*
* _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)
int zone;
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int dst;
{
struct zone *zp;
char sign;
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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, sizeof(czone),
"GMT%c%d:%02d",sign,zone / 60,zone % 60);
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return(czone);
}