VirtualBox

source: vbox/trunk/src/VBox/Runtime/r3/posix/timelocal-posix.cpp@ 30552

Last change on this file since 30552 was 28800, checked in by vboxsync, 15 years ago

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1/* $Id $ */
2/** @file
3 * IPRT - Local Time, Posix.
4 */
5
6/*
7 * Copyright (C) 2006-2007 Oracle Corporation
8 *
9 * This file is part of VirtualBox Open Source Edition (OSE), as
10 * available from http://www.virtualbox.org. This file is free software;
11 * you can redistribute it and/or modify it under the terms of the GNU
12 * General Public License (GPL) as published by the Free Software
13 * Foundation, in version 2 as it comes in the "COPYING" file of the
14 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16 *
17 * The contents of this file may alternatively be used under the terms
18 * of the Common Development and Distribution License Version 1.0
19 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20 * VirtualBox OSE distribution, in which case the provisions of the
21 * CDDL are applicable instead of those of the GPL.
22 *
23 * You may elect to license modified versions of this file under the
24 * terms and conditions of either the GPL or the CDDL or both.
25 */
26
27
28/*******************************************************************************
29* Header Files *
30*******************************************************************************/
31#define LOG_GROUP RTLOGGROUP_TIME
32#define RTTIME_INCL_TIMEVAL
33#include <iprt/types.h>
34#include <sys/time.h>
35#include <time.h>
36
37#include <iprt/time.h>
38
39
40/**
41 * This tries to find the UTC offset for a given timespec.
42 *
43 * It does probably not take into account changes in daylight
44 * saving over the years or similar stuff.
45 *
46 * @returns UTC offset in nanoseconds.
47 * @param pTime The time.
48 * @param fCurrentTime Whether the input is current time or not.
49 * This is for avoid infinit recursion on errors in the fallback path.
50 */
51static int64_t rtTimeLocalUTCOffset(PCRTTIMESPEC pTime, bool fCurrentTime)
52{
53 RTTIMESPEC Fallback;
54
55 /*
56 * Convert to time_t.
57 */
58 int64_t i64UnixTime = RTTimeSpecGetSeconds(pTime);
59 time_t UnixTime = i64UnixTime;
60 if (UnixTime != i64UnixTime)
61 return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
62
63 /*
64 * Explode it as both local and uct time.
65 */
66 struct tm TmLocal;
67 if ( !localtime_r(&UnixTime, &TmLocal)
68 || !TmLocal.tm_year)
69 return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
70 struct tm TmUct;
71 if (!gmtime_r(&UnixTime, &TmUct))
72 return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
73
74 /*
75 * Calc the difference (if any).
76 * We ASSUME that the difference is less that 24 hours.
77 */
78 if ( TmLocal.tm_hour == TmUct.tm_hour
79 && TmLocal.tm_min == TmUct.tm_min
80 && TmLocal.tm_sec == TmUct.tm_sec
81 && TmLocal.tm_mday == TmUct.tm_mday)
82 return 0;
83
84 int LocalSecs = TmLocal.tm_hour * 3600
85 + TmLocal.tm_min * 60
86 + TmLocal.tm_sec;
87 int UctSecs = TmUct.tm_hour * 3600
88 + TmUct.tm_min * 60
89 + TmUct.tm_sec;
90 if (TmLocal.tm_mday != TmUct.tm_mday)
91 {
92 if ( ( TmLocal.tm_mday > TmUct.tm_mday
93 && TmUct.tm_mday != 1)
94 || TmLocal.tm_mday == 1)
95 LocalSecs += 24*60*60;
96 else
97 UctSecs += 24*60*60;
98 }
99
100 return (LocalSecs - UctSecs) * INT64_C(1000000000);
101}
102
103
104/**
105 * Gets the delta between UTC and local time.
106 *
107 * @code
108 * RTTIMESPEC LocalTime;
109 * RTTimeSpecAddNano(RTTimeNow(&LocalTime), RTTimeLocalDeltaNano());
110 * @endcode
111 *
112 * @returns Returns the nanosecond delta between UTC and local time.
113 */
114RTDECL(int64_t) RTTimeLocalDeltaNano(void)
115{
116 RTTIMESPEC Time;
117 return rtTimeLocalUTCOffset(RTTimeNow(&Time), true /* current time, skip fallback */);
118}
119
120
121/**
122 * Explodes a time spec to the localized timezone.
123 *
124 * @returns pTime.
125 * @param pTime Where to store the exploded time.
126 * @param pTimeSpec The time spec to exploded. (UTC)
127 */
128RTDECL(PRTTIME) RTTimeLocalExplode(PRTTIME pTime, PCRTTIMESPEC pTimeSpec)
129{
130 RTTIMESPEC LocalTime = *pTimeSpec;
131 RTTimeSpecAddNano(&LocalTime, rtTimeLocalUTCOffset(&LocalTime, true /* current time, skip fallback */));
132 pTime = RTTimeExplode(pTime, &LocalTime);
133 if (pTime)
134 pTime->fFlags = (pTime->fFlags & ~RTTIME_FLAGS_TYPE_MASK) | RTTIME_FLAGS_TYPE_LOCAL;
135 return pTime;
136}
137
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