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