gen/timezone.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1987, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  */
  54
  55
  56 #include <sys/types.h>
  57 #include <sys/time.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <tzfile.h>
  62
  63 char *_tztab();
  64
  65 /*
  66  * timezone --
  67  *      The arguments are the number of minutes of time you are westward
  68  *      from Greenwich and whether DST is in effect.  It returns a string
  69  *      giving the name of the local timezone.  Should be replaced, in the
  70  *      application code, by a call to localtime.
  71  */
  72
  73 static char     czone[TZ_MAX_CHARS];            /* space for zone name */
  74
  75 char *
  76 timezone(zone, dst)
  77         int     zone,
  78                 dst;
  79 {
  80         register char   *beg,
  81                         *end;
  82
  83         if (beg = getenv("TZNAME")) {           /* set in environment */
  84                 if (end = index(beg, ',')) {    /* "PST,PDT" */
  85                         if (dst)
  86                                 return(++end);
  87                         *end = '\0';
  88                         (void)strncpy(czone,beg,sizeof(czone) - 1);
  89                         czone[sizeof(czone) - 1] = '\0';
  90                         *end = ',';
  91                         return(czone);
  92                 }
  93                 return(beg);
  94         }
  95         return(_tztab(zone,dst));       /* default: table or created zone */
  96 }
  97
  98 static struct zone {
  99         int     offset;
 100         char    *stdzone;
 101         char    *dlzone;
 102 } zonetab[] = {
 103         -1*60,  "MET",  "MET DST",      /* Middle European */
 104         -2*60,  "EET",  "EET DST",      /* Eastern European */
 105         4*60,   "AST",  "ADT",          /* Atlantic */
 106         5*60,   "EST",  "EDT",          /* Eastern */
 107         6*60,   "CST",  "CDT",          /* Central */
 108         7*60,   "MST",  "MDT",          /* Mountain */
 109         8*60,   "PST",  "PDT",          /* Pacific */
 110 #ifdef notdef
 111         /* there's no way to distinguish this from WET */
 112         0,      "GMT",  0,              /* Greenwich */
 113 #endif
 114         0*60,   "WET",  "WET DST",      /* Western European */
 115         -10*60, "EST",  "EST",          /* Aust: Eastern */
 116      -10*60+30, "CST",  "CST",          /* Aust: Central */
 117         -8*60,  "WST",  0,              /* Aust: Western */
 118         -1
 119 };
 120
 121 /*
 122  * _tztab --
 123  *      check static tables or create a new zone name; broken out so that
 124  *      we can make a guess as to what the zone is if the standard tables
 125  *      aren't in place in /etc.  DO NOT USE THIS ROUTINE OUTSIDE OF THE
 126  *      STANDARD LIBRARY.
 127  */
 128 char *
 129 _tztab(zone,dst)
 130         register int    zone;
 131         int     dst;
 132 {
 133         register struct zone    *zp;
 134         register char   sign;
 135
 136         for (zp = zonetab; zp->offset != -1;++zp)       /* static tables */
 137                 if (zp->offset == zone) {
 138                         if (dst && zp->dlzone)
 139                                 return(zp->dlzone);
 140                         if (!dst && zp->stdzone)
 141                                 return(zp->stdzone);
 142                 }
 143
 144         if (zone < 0) {                                 /* create one */
 145                 zone = -zone;
 146                 sign = '+';
 147         }
 148         else
 149                 sign = '-';
 150         (void)sprintf(czone,"GMT%c%d:%02d",sign,zone / 60,zone % 60);
 151         return(czone);
 152 }