1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1987, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/types.h>
33#include <sys/time.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <string.h>
37#define TZ_MAX_CHARS 255
38
39static char *_tztab(int, int);
40
41/*
42 * timezone --
43 *	The arguments are the number of minutes of time you are westward
44 *	from Greenwich and whether DST is in effect.  It returns a string
45 *	giving the name of the local timezone.  Should be replaced, in the
46 *	application code, by a call to localtime.
47 */
48
49static char	czone[TZ_MAX_CHARS];		/* space for zone name */
50
51char *
52__timezone_compat(int zone, int dst)
53{
54	char	*beg,
55			*end;
56
57	if ( (beg = getenv("TZNAME")) ) {	/* set in environment */
58		if ((end = strchr(beg, ','))) {	/* "PST,PDT" */
59			if (dst)
60				return(++end);
61			*end = '\0';
62			(void)strncpy(czone,beg,sizeof(czone) - 1);
63			czone[sizeof(czone) - 1] = '\0';
64			*end = ',';
65			return(czone);
66		}
67		return(beg);
68	}
69	return(_tztab(zone,dst));	/* default: table or created zone */
70}
71__sym_compat(timezone, __timezone_compat, FBSD_1.0);
72
73static struct zone {
74	int	offset;
75	char	*stdzone;
76	char	*dlzone;
77} zonetab[] = {
78	{-1*60,	"MET",	"MET DST"},	/* Middle European */
79	{-2*60,	"EET",	"EET DST"},	/* Eastern European */
80	{4*60,	"AST",	"ADT"},		/* Atlantic */
81	{5*60,	"EST",	"EDT"},		/* Eastern */
82	{6*60,	"CST",	"CDT"},		/* Central */
83	{7*60,	"MST",	"MDT"},		/* Mountain */
84	{8*60,	"PST",	"PDT"},		/* Pacific */
85#ifdef notdef
86	/* there's no way to distinguish this from WET */
87	{0,	"GMT",	0},		/* Greenwich */
88#endif
89	{0*60,	"WET",	"WET DST"},	/* Western European */
90	{-10*60,"EST",	"EST"},		/* Aust: Eastern */
91     {-10*60+30,"CST",	"CST"},		/* Aust: Central */
92	{-8*60,	"WST",	0},		/* Aust: Western */
93	{-1}
94};
95
96/*
97 * _tztab --
98 *	check static tables or create a new zone name; broken out so that
99 *	we can make a guess as to what the zone is if the standard tables
100 *	aren't in place in /etc.  DO NOT USE THIS ROUTINE OUTSIDE OF THE
101 *	STANDARD LIBRARY.
102 */
103static char *
104_tztab(int zone, int dst)
105{
106	struct zone	*zp;
107	char	sign;
108
109	for (zp = zonetab; zp->offset != -1;++zp)	/* static tables */
110		if (zp->offset == zone) {
111			if (dst && zp->dlzone)
112				return(zp->dlzone);
113			if (!dst && zp->stdzone)
114				return(zp->stdzone);
115		}
116
117	if (zone < 0) {					/* create one */
118		zone = -zone;
119		sign = '+';
120	}
121	else
122		sign = '-';
123	(void)snprintf(czone, sizeof(czone),
124	    "GMT%c%d:%02d",sign,zone / 60,zone % 60);
125	return(czone);
126}
127