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 * 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 * 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