gen/4.2/timezone.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1986 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"
      /* from UCB 4.4 83/09/25 */

/*
 * The arguments are the number of minutes of time
 * you are westward from Greenwich and whether DST is in effect.
 * It returns a string
 * giving the name of the local timezone.
 *
 * Sorry, I don't know all the names.
 */

static struct zone {
    int offset;
    char    *stdzone;
    char    *dlzone;
} zonetab[] = {
    -12*60,    "NZST", "NZDT",  /* New Zealand */
    -10*60,    "EST",  "EST",   /* Aust: Eastern */
    -10*60+30, "CST",  "CST",   /* Aust: Central */
     -8*60,    "WST",  0,       /* Aust: Western */
     -9*60,    "JST",  0,       /* Japanese */
      0*60,    "GMT",  "BST",   /* Great Britain and Eire */
     -1*60,    "MET",  "MET DST",   /* Middle European */
     -2*60,    "EET",  "EET DST",   /* Eastern European */
      3*60+30, "NST",  "NDT",   /* Newfoundland */
      4*60,    "AST",  "ADT",   /* Atlantic */
      5*60,    "EST",  "EDT",   /* Eastern */
      6*60,    "CST",  "CDT",   /* Central */
      7*60,    "MST",  "MDT",   /* Mountain */
      8*60,    "PST",  "PDT",   /* Pacific */
      9*60,    "YST",  "YDT",   /* Yukon */
     10*60,    "HST",  "HDT",   /* Hawaiian */
    -1
};

char *timezone(zone, dst)
{
    register struct zone *zp;
    static char czone[10];
    char *sign;
    register char *p, *q;
    char *getenv(), *index();

    if (p = getenv("TZNAME")) {
        if (q = index(p, ',')) {
            if (dst)
                return(++q);
            else {
                *q = '\0';
                strncpy(czone, p, sizeof(czone)-1);
                czone[sizeof(czone)-1] = '\0';
                *q = ',';
                return (czone);
            }
        }
        return(p);
    }
    for (zp=zonetab; zp->offset!=-1; zp++)
        if (zp->offset==zone) {
            if (dst && zp->dlzone)
                return(zp->dlzone);
            if (!dst && zp->stdzone)
                return(zp->stdzone);
        }
    if (zone<0) {
        zone = -zone;
        sign = "+";
    } else
        sign = "-";
    sprintf(czone, "GMT%s%d:%02d", sign, zone/60, zone%60);
    return(czone);
}