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