80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
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/* $NetBSD: gmt2local.c,v 1.1.1.1 1997/10/03 17:24:11 christos Exp $ */
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/*
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* Copyright (c) 1997
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that: (1) source code distributions
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* retain the above copyright notice and this paragraph in its entirety, (2)
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* distributions including binary code include the above copyright notice and
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* this paragraph in its entirety in the documentation or other materials
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* provided with the distribution, and (3) all advertising materials mentioning
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* features or use of this software display the following acknowledgement:
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* ``This product includes software developed by the University of California,
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* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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* the University nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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#if 0
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static const char rcsid[] =
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"@(#) Header: gmt2local.c,v 1.2 97/01/23 22:31:25 leres Exp (LBL)";
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#else
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__RCSID("$NetBSD: gmt2local.c,v 1.1.1.1 1997/10/03 17:24:11 christos Exp $");
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#endif
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#endif
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#include <sys/types.h>
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#include <sys/time.h>
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#include <stdio.h>
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#ifdef TIME_WITH_SYS_TIME
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#include <time.h>
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#endif
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#include "gnuc.h"
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#ifdef HAVE_OS_PROTO_H
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#include "os-proto.h"
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#endif
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#include "gmt2local.h"
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/*
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* Returns the difference between gmt and local time in seconds.
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* Use gmtime() and localtime() to keep things simple.
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*/
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int32_t
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gmt2local(time_t t)
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{
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register int dt, dir;
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register struct tm *gmt, *loc;
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struct tm sgmt;
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if (t == 0)
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t = time(NULL);
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gmt = &sgmt;
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*gmt = *gmtime(&t);
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loc = localtime(&t);
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dt = (loc->tm_hour - gmt->tm_hour) * 60 * 60 +
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(loc->tm_min - gmt->tm_min) * 60;
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/*
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* If the year or julian day is different, we span 00:00 GMT
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* and must add or subtract a day. Check the year first to
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* avoid problems when the julian day wraps.
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*/
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dir = loc->tm_year - gmt->tm_year;
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if (dir == 0)
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dir = loc->tm_yday - gmt->tm_yday;
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dt += dir * 24 * 60 * 60;
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return (dt);
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}
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