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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)timezone.c  8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/gen/timezone.c,v 1.6 2007/01/09 00:27:55 imp Exp $");
  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();
  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(zone, dst)
  57         int     zone,
  58                 dst;
  59 {
  60         char    *beg,
  61                         *end;
  62
  63         if ( (beg = getenv("TZNAME")) ) {       /* set in environment */
  64                 if ( (end = index(beg, ',')) ) {/* "PST,PDT" */
  65                         if (dst)
  66                                 return(++end);
  67                         *end = '\0';
  68                         (void)strncpy(czone,beg,sizeof(czone) - 1);
  69                         czone[sizeof(czone) - 1] = '\0';
  70                         *end = ',';
  71                         return(czone);
  72                 }
  73                 return(beg);
  74         }
  75         return(_tztab(zone,dst));       /* default: table or created zone */
  76 }
  77
  78 static struct zone {
  79         int     offset;
  80         char    *stdzone;
  81         char    *dlzone;
  82 } zonetab[] = {
  83         {-1*60, "MET",  "MET DST"},     /* Middle European */
  84         {-2*60, "EET",  "EET DST"},     /* Eastern European */
  85         {4*60,  "AST",  "ADT"},         /* Atlantic */
  86         {5*60,  "EST",  "EDT"},         /* Eastern */
  87         {6*60,  "CST",  "CDT"},         /* Central */
  88         {7*60,  "MST",  "MDT"},         /* Mountain */
  89         {8*60,  "PST",  "PDT"},         /* Pacific */
  90 #ifdef notdef
  91         /* there's no way to distinguish this from WET */
  92         {0,     "GMT",  0},             /* Greenwich */
  93 #endif
  94         {0*60,  "WET",  "WET DST"},     /* Western European */
  95         {-10*60,"EST",  "EST"},         /* Aust: Eastern */
  96      {-10*60+30,"CST",  "CST"},         /* Aust: Central */
  97         {-8*60, "WST",  0},             /* Aust: Western */
  98         {-1}
  99 };
 100
 101 /*
 102  * _tztab --
 103  *      check static tables or create a new zone name; broken out so that
 104  *      we can make a guess as to what the zone is if the standard tables
 105  *      aren't in place in /etc.  DO NOT USE THIS ROUTINE OUTSIDE OF THE
 106  *      STANDARD LIBRARY.
 107  */
 108 char *
 109 _tztab(zone,dst)
 110         int     zone;
 111         int     dst;
 112 {
 113         struct zone     *zp;
 114         char    sign;
 115
 116         for (zp = zonetab; zp->offset != -1;++zp)       /* static tables */
 117                 if (zp->offset == zone) {
 118                         if (dst && zp->dlzone)
 119                                 return(zp->dlzone);
 120                         if (!dst && zp->stdzone)
 121                                 return(zp->stdzone);
 122                 }
 123
 124         if (zone < 0) {                                 /* create one */
 125                 zone = -zone;
 126                 sign = '+';
 127         }
 128         else
 129                 sign = '-';
 130         (void)snprintf(czone, sizeof(czone),
 131             "GMT%c%d:%02d",sign,zone / 60,zone % 60);
 132         return(czone);
 133 }