xref: /titanic_41/usr/src/lib/libbc/libc/gen/4.2/timezone.c (revision ea394cb00fd96864e34d2841b4a22357b621c78f)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 1986 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 	  /* from UCB 4.4 83/09/25 */
29 
30 /*
31  * The arguments are the number of minutes of time
32  * you are westward from Greenwich and whether DST is in effect.
33  * It returns a string
34  * giving the name of the local timezone.
35  *
36  * Sorry, I don't know all the names.
37  */
38 
39 static struct zone {
40 	int	offset;
41 	char	*stdzone;
42 	char	*dlzone;
43 } zonetab[] = {
44 	-12*60,    "NZST", "NZDT",	/* New Zealand */
45 	-10*60,    "EST",  "EST",	/* Aust: Eastern */
46 	-10*60+30, "CST",  "CST",	/* Aust: Central */
47 	 -8*60,    "WST",  0,		/* Aust: Western */
48 	 -9*60,    "JST",  0,		/* Japanese */
49 	  0*60,    "GMT",  "BST",	/* Great Britain and Eire */
50 	 -1*60,    "MET",  "MET DST",	/* Middle European */
51 	 -2*60,    "EET",  "EET DST",	/* Eastern European */
52 	  3*60+30, "NST",  "NDT",	/* Newfoundland */
53 	  4*60,    "AST",  "ADT",	/* Atlantic */
54 	  5*60,    "EST",  "EDT",	/* Eastern */
55 	  6*60,    "CST",  "CDT",	/* Central */
56 	  7*60,    "MST",  "MDT",	/* Mountain */
57 	  8*60,    "PST",  "PDT",	/* Pacific */
58 	  9*60,    "YST",  "YDT",	/* Yukon */
59 	 10*60,    "HST",  "HDT",	/* Hawaiian */
60 	-1
61 };
62 
63 char *timezone(zone, dst)
64 {
65 	register struct zone *zp;
66 	static char czone[10];
67 	char *sign;
68 	register char *p, *q;
69 	char *getenv(), *index();
70 
71 	if (p = getenv("TZNAME")) {
72 		if (q = index(p, ',')) {
73 			if (dst)
74 				return(++q);
75 			else {
76 				*q = '\0';
77 				strncpy(czone, p, sizeof(czone)-1);
78 				czone[sizeof(czone)-1] = '\0';
79 				*q = ',';
80 				return (czone);
81 			}
82 		}
83 		return(p);
84 	}
85 	for (zp=zonetab; zp->offset!=-1; zp++)
86 		if (zp->offset==zone) {
87 			if (dst && zp->dlzone)
88 				return(zp->dlzone);
89 			if (!dst && zp->stdzone)
90 				return(zp->stdzone);
91 		}
92 	if (zone<0) {
93 		zone = -zone;
94 		sign = "+";
95 	} else
96 		sign = "-";
97 	sprintf(czone, "GMT%s%d:%02d", sign, zone/60, zone%60);
98 	return(czone);
99 }
100