summaryrefslogtreecommitdiff
path: root/lib/libc/gen/timezone.c
blob: 498243f8c3fc40629c152908e02579d7ab8a3dc6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
/*
 * 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 rcsid[] = "$OpenBSD: timezone.c,v 1.5 2001/06/27 00:58:54 lebel Exp $";
#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" */
			if (dst)
				return(++end);
			*end = '\0';
			strlcpy(czone,beg,sizeof(czone));
			*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, sizeof czone, "GMT%c%d:%02d",
	    sign,zone / 60,zone % 60);
	return(czone);
}