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 * 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 * 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