gen/FreeBSD/timezone.c

   1 /*
   2  * Copyright (c) 1987, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)timezone.c  8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/gen/timezone.c,v 1.5 2002/02/01 01:08:48 obrien Exp $");
  39
  40 #include <sys/types.h>
  41 #include <sys/time.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #define TZ_MAX_CHARS 255
  46
  47 char *_tztab();
  48
  49 /*
  50  * timezone --
  51  *      The arguments are the number of minutes of time you are westward
  52  *      from Greenwich and whether DST is in effect.  It returns a string
  53  *      giving the name of the local timezone.  Should be replaced, in the
  54  *      application code, by a call to localtime.
  55  */
  56
  57 static char     czone[TZ_MAX_CHARS];            /* space for zone name */
  58
  59 char *
  60 timezone(zone, dst)
  61         int     zone,
  62                 dst;
  63 {
  64         char    *beg,
  65                         *end;
  66
  67         if ( (beg = getenv("TZNAME")) ) {       /* set in environment */
  68                 if ( (end = index(beg, ',')) ) {/* "PST,PDT" */
  69                         if (dst)
  70                                 return(++end);
  71                         *end = '\0';
  72                         (void)strncpy(czone,beg,sizeof(czone) - 1);
  73                         czone[sizeof(czone) - 1] = '\0';
  74                         *end = ',';
  75                         return(czone);
  76                 }
  77                 return(beg);
  78         }
  79         return(_tztab(zone,dst));       /* default: table or created zone */
  80 }
  81
  82 static struct zone {
  83         int     offset;
  84         char    *stdzone;
  85         char    *dlzone;
  86 } zonetab[] = {
  87         {-1*60, "MET",  "MET DST"},     /* Middle European */
  88         {-2*60, "EET",  "EET DST"},     /* Eastern European */
  89         {4*60,  "AST",  "ADT"},         /* Atlantic */
  90         {5*60,  "EST",  "EDT"},         /* Eastern */
  91         {6*60,  "CST",  "CDT"},         /* Central */
  92         {7*60,  "MST",  "MDT"},         /* Mountain */
  93         {8*60,  "PST",  "PDT"},         /* Pacific */
  94 #ifdef notdef
  95         /* there's no way to distinguish this from WET */
  96         {0,     "GMT",  0},             /* Greenwich */
  97 #endif
  98         {0*60,  "WET",  "WET DST"},     /* Western European */
  99         {-10*60,"EST",  "EST"},         /* Aust: Eastern */
 100      {-10*60+30,"CST",  "CST"},         /* Aust: Central */
 101         {-8*60, "WST",  0},             /* Aust: Western */
 102         {-1}
 103 };
 104
 105 /*
 106  * _tztab --
 107  *      check static tables or create a new zone name; broken out so that
 108  *      we can make a guess as to what the zone is if the standard tables
 109  *      aren't in place in /etc.  DO NOT USE THIS ROUTINE OUTSIDE OF THE
 110  *      STANDARD LIBRARY.
 111  */
 112 char *
 113 _tztab(zone,dst)
 114         int     zone;
 115         int     dst;
 116 {
 117         struct zone     *zp;
 118         char    sign;
 119
 120         for (zp = zonetab; zp->offset != -1;++zp)       /* static tables */
 121                 if (zp->offset == zone) {
 122                         if (dst && zp->dlzone)
 123                                 return(zp->dlzone);
 124                         if (!dst && zp->stdzone)
 125                                 return(zp->stdzone);
 126                 }
 127
 128         if (zone < 0) {                                 /* create one */
 129                 zone = -zone;
 130                 sign = '+';
 131         }
 132         else
 133                 sign = '-';
 134         (void)snprintf(czone, sizeof(czone),
 135             "GMT%c%d:%02d",sign,zone / 60,zone % 60);
 136         return(czone);
 137 }