[dragonfly.git] / contrib / tcpdump / gmt2local.c

/*
 * Copyright (c) 1997
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/gmt2local.c,v 1.9 2003/11/16 09:36:09 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <stdio.h>

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

#include "gmt2local.h"

/*
 * Returns the difference between gmt and local time in seconds.
 * Use gmtime() and localtime() to keep things simple.
 */
int32_t
gmt2local(time_t t)
{
	register int dt, dir;
	register struct tm *gmt, *loc;
	struct tm sgmt;

	if (t == 0)
		t = time(NULL);
	gmt = &sgmt;
	*gmt = *gmtime(&t);
	loc = localtime(&t);
	dt = (loc->tm_hour - gmt->tm_hour) * 60 * 60 +
	    (loc->tm_min - gmt->tm_min) * 60;

	/*
	 * If the year or julian day is different, we span 00:00 GMT
	 * and must add or subtract a day. Check the year first to
	 * avoid problems when the julian day wraps.
	 */
	dir = loc->tm_year - gmt->tm_year;
	if (dir == 0)
		dir = loc->tm_yday - gmt->tm_yday;
	dt += dir * 24 * 60 * 60;

	return (dt);
}
Commit	Line	Data
c8cf0f94 PA	1	/*
	2	* Copyright (c) 1997
	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: (1) source code distributions
	7	* retain the above copyright notice and this paragraph in its entirety, (2)
	8	* distributions including binary code include the above copyright notice and
	9	* this paragraph in its entirety in the documentation or other materials
	10	* provided with the distribution, and (3) all advertising materials mentioning
	11	* features or use of this software display the following acknowledgement:
	12	* ``This product includes software developed by the University of California,
	13	* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
	14	* the University nor the names of its contributors may be used to endorse
	15	* or promote products derived from this software without specific prior
	16	* written permission.
	17	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
	18	* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
	19	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	20	*/
	21
	22	#ifndef lint
	23	static const char rcsid[] _U_ =
	24	"@(#) $Header: /tcpdump/master/tcpdump/gmt2local.c,v 1.9 2003/11/16 09:36:09 guy Exp $ (LBL)";
	25	#endif
	26
	27	#ifdef HAVE_CONFIG_H
	28	#include "config.h"
	29	#endif
	30
	31	#include <tcpdump-stdinc.h>
	32
	33	#include <stdio.h>
	34
	35	#ifdef HAVE_OS_PROTO_H
	36	#include "os-proto.h"
	37	#endif
	38
	39	#include "gmt2local.h"
	40
	41	/*
	42	* Returns the difference between gmt and local time in seconds.
	43	* Use gmtime() and localtime() to keep things simple.
	44	*/
	45	int32_t
	46	gmt2local(time_t t)
	47	{
	48	register int dt, dir;
	49	register struct tm gmt, loc;
	50	struct tm sgmt;
	51
	52	if (t == 0)
	53	t = time(NULL);
	54	gmt = &sgmt;
	55	gmt = gmtime(&t);
	56	loc = localtime(&t);
	57	dt = (loc->tm_hour - gmt->tm_hour) * 60 * 60 +
	58	(loc->tm_min - gmt->tm_min) * 60;
	59
	60	/*
	61	* If the year or julian day is different, we span 00:00 GMT
	62	* and must add or subtract a day. Check the year first to
	63	* avoid problems when the julian day wraps.
	64	*/
65	dir = loc->tm_year - gmt->tm_year;
66	if (dir == 0)
67	dir = loc->tm_yday - gmt->tm_yday;
68	dt += dir * 24 * 60 * 60;
69
70	return (dt);
71	}