gen/timezone.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1987, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 #include <sys/types.h>
  60 #include <sys/time.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64 #include <tzfile.h>
  65
  66 char *_tztab();
  67
  68 /*
  69  * timezone --
  70  *      The arguments are the number of minutes of time you are westward
  71  *      from Greenwich and whether DST is in effect.  It returns a string
  72  *      giving the name of the local timezone.  Should be replaced, in the
  73  *      application code, by a call to localtime.
  74  */
  75
  76 static char     czone[TZ_MAX_CHARS];            /* space for zone name */
  77
  78 char *
  79 timezone(zone, dst)
  80         int     zone,
  81                 dst;
  82 {
  83         register char   *beg,
  84                         *end;
  85
  86         if (beg = getenv("TZNAME")) {           /* set in environment */
  87                 if (end = index(beg, ',')) {    /* "PST,PDT" */
  88                         if (dst)
  89                                 return(++end);
  90                         *end = '\0';
  91                         (void)strncpy(czone,beg,sizeof(czone) - 1);
  92                         czone[sizeof(czone) - 1] = '\0';
  93                         *end = ',';
  94                         return(czone);
  95                 }
  96                 return(beg);
  97         }
  98         return(_tztab(zone,dst));       /* default: table or created zone */
  99 }
 100
 101 static struct zone {
 102         int     offset;
 103         char    *stdzone;
 104         char    *dlzone;
 105 } zonetab[] = {
 106         -1*60,  "MET",  "MET DST",      /* Middle European */
 107         -2*60,  "EET",  "EET DST",      /* Eastern European */
 108         4*60,   "AST",  "ADT",          /* Atlantic */
 109         5*60,   "EST",  "EDT",          /* Eastern */
 110         6*60,   "CST",  "CDT",          /* Central */
 111         7*60,   "MST",  "MDT",          /* Mountain */
 112         8*60,   "PST",  "PDT",          /* Pacific */
 113 #ifdef notdef
 114         /* there's no way to distinguish this from WET */
 115         0,      "GMT",  0,              /* Greenwich */
 116 #endif
 117         0*60,   "WET",  "WET DST",      /* Western European */
 118         -10*60, "EST",  "EST",          /* Aust: Eastern */
 119      -10*60+30, "CST",  "CST",          /* Aust: Central */
 120         -8*60,  "WST",  0,              /* Aust: Western */
 121         -1
 122 };
 123
 124 /*
 125  * _tztab --
 126  *      check static tables or create a new zone name; broken out so that
 127  *      we can make a guess as to what the zone is if the standard tables
 128  *      aren't in place in /etc.  DO NOT USE THIS ROUTINE OUTSIDE OF THE
 129  *      STANDARD LIBRARY.
 130  */
 131 char *
 132 _tztab(zone,dst)
 133         register int    zone;
 134         int     dst;
 135 {
 136         register struct zone    *zp;
 137         register char   sign;
 138
 139         for (zp = zonetab; zp->offset != -1;++zp)       /* static tables */
 140                 if (zp->offset == zone) {
 141                         if (dst && zp->dlzone)
 142                                 return(zp->dlzone);
 143                         if (!dst && zp->stdzone)
 144                                 return(zp->stdzone);
 145                 }
 146
 147         if (zone < 0) {                                 /* create one */
 148                 zone = -zone;
 149                 sign = '+';
 150         }
 151         else
 152                 sign = '-';
 153         (void)sprintf(czone,"GMT%c%d:%02d",sign,zone / 60,zone % 60);
 154         return(czone);
 155 }