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/cdefs.h>
33 __SCCSID("@(#)timezone.c 8.1 (Berkeley) 6/4/93");
34 __FBSDID("$FreeBSD$");
35
36 #include <sys/types.h>
37 #include <sys/time.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #define TZ_MAX_CHARS 255
42
43 char *_tztab(int, int);
44
45 /*
46 * timezone --
47 * The arguments are the number of minutes of time you are westward
48 * from Greenwich and whether DST is in effect. It returns a string
49 * giving the name of the local timezone. Should be replaced, in the
50 * application code, by a call to localtime.
51 */
52
53 static char czone[TZ_MAX_CHARS]; /* space for zone name */
54
55 char *
timezone(int zone,int dst)56 timezone(int zone, int dst)
57 {
58 char *beg,
59 *end;
60
61 if ( (beg = getenv("TZNAME")) ) { /* set in environment */
62 if ((end = strchr(beg, ','))) { /* "PST,PDT" */
63 if (dst)
64 return(++end);
65 *end = '\0';
66 (void)strncpy(czone,beg,sizeof(czone) - 1);
67 czone[sizeof(czone) - 1] = '\0';
68 *end = ',';
69 return(czone);
70 }
71 return(beg);
72 }
73 return(_tztab(zone,dst)); /* default: table or created zone */
74 }
75
76 static struct zone {
77 int offset;
78 char *stdzone;
79 char *dlzone;
80 } zonetab[] = {
81 {-1*60, "MET", "MET DST"}, /* Middle European */
82 {-2*60, "EET", "EET DST"}, /* Eastern European */
83 {4*60, "AST", "ADT"}, /* Atlantic */
84 {5*60, "EST", "EDT"}, /* Eastern */
85 {6*60, "CST", "CDT"}, /* Central */
86 {7*60, "MST", "MDT"}, /* Mountain */
87 {8*60, "PST", "PDT"}, /* Pacific */
88 #ifdef notdef
89 /* there's no way to distinguish this from WET */
90 {0, "GMT", 0}, /* Greenwich */
91 #endif
92 {0*60, "WET", "WET DST"}, /* Western European */
93 {-10*60,"EST", "EST"}, /* Aust: Eastern */
94 {-10*60+30,"CST", "CST"}, /* Aust: Central */
95 {-8*60, "WST", 0}, /* Aust: Western */
96 {-1}
97 };
98
99 /*
100 * _tztab --
101 * check static tables or create a new zone name; broken out so that
102 * we can make a guess as to what the zone is if the standard tables
103 * aren't in place in /etc. DO NOT USE THIS ROUTINE OUTSIDE OF THE
104 * STANDARD LIBRARY.
105 */
106 char *
_tztab(int zone,int dst)107 _tztab(int zone, int dst)
108 {
109 struct zone *zp;
110 char sign;
111
112 for (zp = zonetab; zp->offset != -1;++zp) /* static tables */
113 if (zp->offset == zone) {
114 if (dst && zp->dlzone)
115 return(zp->dlzone);
116 if (!dst && zp->stdzone)
117 return(zp->stdzone);
118 }
119
120 if (zone < 0) { /* create one */
121 zone = -zone;
122 sign = '+';
123 }
124 else
125 sign = '-';
126 (void)snprintf(czone, sizeof(czone),
127 "GMT%c%d:%02d",sign,zone / 60,zone % 60);
128 return(czone);
129 }
130