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 } 72
