1 | /* $Id $ */
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2 | /** @file
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3 | * IPRT - Local Time, Posix.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2006-2017 Oracle Corporation
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8 | *
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9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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10 | * available from http://www.virtualbox.org. This file is free software;
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11 | * you can redistribute it and/or modify it under the terms of the GNU
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12 | * General Public License (GPL) as published by the Free Software
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13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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16 | *
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17 | * The contents of this file may alternatively be used under the terms
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18 | * of the Common Development and Distribution License Version 1.0
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19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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20 | * VirtualBox OSE distribution, in which case the provisions of the
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21 | * CDDL are applicable instead of those of the GPL.
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22 | *
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23 | * You may elect to license modified versions of this file under the
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24 | * terms and conditions of either the GPL or the CDDL or both.
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25 | */
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26 |
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27 |
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28 | /*********************************************************************************************************************************
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29 | * Header Files *
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30 | *********************************************************************************************************************************/
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31 | #define LOG_GROUP RTLOGGROUP_TIME
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32 | #define RTTIME_INCL_TIMEVAL
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33 | #include <iprt/types.h>
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34 | #include <iprt/assert.h>
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35 |
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36 | #include <sys/time.h>
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37 | #include <time.h>
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38 |
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39 | #include <iprt/time.h>
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40 |
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41 |
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42 | /**
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43 | * This tries to find the UTC offset for a given timespec.
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44 | *
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45 | * It does probably not take into account changes in daylight
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46 | * saving over the years or similar stuff.
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47 | *
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48 | * @returns UTC offset in nanoseconds.
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49 | * @param pTime The time.
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50 | * @param fCurrentTime Whether the input is current time or not.
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51 | * This is for avoid infinit recursion on errors in the fallback path.
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52 | */
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53 | static int64_t rtTimeLocalUTCOffset(PCRTTIMESPEC pTime, bool fCurrentTime)
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54 | {
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55 | RTTIMESPEC Fallback;
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56 |
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57 | /*
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58 | * Convert to time_t.
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59 | */
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60 | int64_t i64UnixTime = RTTimeSpecGetSeconds(pTime);
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61 | time_t UnixTime = i64UnixTime;
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62 | if (UnixTime != i64UnixTime)
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63 | return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
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64 |
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65 | /*
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66 | * Explode it as both local and UTC time.
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67 | */
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68 | struct tm TmLocal;
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69 | if ( !localtime_r(&UnixTime, &TmLocal)
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70 | || !TmLocal.tm_year)
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71 | return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
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72 | struct tm TmUtc;
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73 | if (!gmtime_r(&UnixTime, &TmUtc))
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74 | return fCurrentTime ? 0 : rtTimeLocalUTCOffset(RTTimeNow(&Fallback), true);
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75 |
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76 | /*
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77 | * Calc the difference (if any).
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78 | * We ASSUME that the difference is less that 24 hours.
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79 | */
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80 | if ( TmLocal.tm_hour == TmUtc.tm_hour
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81 | && TmLocal.tm_min == TmUtc.tm_min
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82 | && TmLocal.tm_sec == TmUtc.tm_sec
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83 | && TmLocal.tm_mday == TmUtc.tm_mday)
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84 | return 0;
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85 |
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86 | int cLocalSecs = TmLocal.tm_hour * 3600
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87 | + TmLocal.tm_min * 60
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88 | + TmLocal.tm_sec;
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89 | int cUtcSecs = TmUtc.tm_hour * 3600
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90 | + TmUtc.tm_min * 60
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91 | + TmUtc.tm_sec;
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92 | if (TmLocal.tm_mday != TmUtc.tm_mday)
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93 | {
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94 | /*
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95 | * Must add 24 hours to the value that is ahead of the other.
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96 | *
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97 | * To determine which is ahead was busted for a long long time (bugref:9078),
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98 | * so here are some examples and two different approaches.
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99 | *
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100 | * TmLocal TmUtc => Add 24:00 to => Diff
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101 | * 2007-04-02 01:00 2007-04-01 23:00 => TmLocal => +02:00
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102 | * 2007-04-01 01:00 2007-03-31 23:00 => TmLocal => +02:00
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103 | * 2007-03-31 01:00 2007-03-30 23:00 => TmLocal => +02:00
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104 | *
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105 | * 2007-04-01 01:00 2007-04-02 23:00 => TmUtc => -02:00
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106 | * 2007-03-31 23:00 2007-04-01 01:00 => TmUtc => -02:00
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107 | * 2007-03-30 23:00 2007-03-31 01:00 => TmUtc => -02:00
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108 | *
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109 | */
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110 | #if 0
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111 | /* Using day of month turned out to be a little complicated. */
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112 | if ( ( TmLocal.tm_mday > TmUtc.tm_mday
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113 | && (TmUtc.tm_mday != 1 || TmLocal.tm_mday < 28) )
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114 | || (TmLocal.tm_mday == 1 && TmUtc.tm_mday >= 28) )
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115 | {
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116 | cLocalSecs += 24*60*60;
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117 | Assert( TmLocal.tm_yday - TmUtc.tm_yday == 1
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118 | || (TmLocal.tm_yday == 0 && TmUtc.tm_yday >= 364 && TmLocal.tm_year == TmUtc.tm_year + 1));
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119 | }
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120 | else
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121 | {
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122 | cUtcSecs += 24*60*60;
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123 | Assert( TmUtc.tm_yday - TmLocal.tm_yday == 1
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124 | || (TmUtc.tm_yday == 0 && TmLocal.tm_yday >= 364 && TmUtc.tm_year == TmLocal.tm_year + 1));
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125 | }
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126 | #else
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127 | /* Using day of year and year is simpler. */
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128 | if ( ( TmLocal.tm_year == TmUtc.tm_year
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129 | && TmLocal.tm_yday > TmUtc.tm_yday)
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130 | || TmLocal.tm_year > TmUtc.tm_year)
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131 | {
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132 | cLocalSecs += 24*60*60;
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133 | Assert( TmLocal.tm_yday - TmUtc.tm_yday == 1
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134 | || (TmLocal.tm_yday == 0 && TmUtc.tm_yday >= 364 && TmLocal.tm_year == TmUtc.tm_year + 1));
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135 | }
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136 | else
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137 | {
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138 | cUtcSecs += 24*60*60;
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139 | Assert( TmUtc.tm_yday - TmLocal.tm_yday == 1
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140 | || (TmUtc.tm_yday == 0 && TmLocal.tm_yday >= 364 && TmUtc.tm_year == TmLocal.tm_year + 1));
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141 | }
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142 | #endif
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143 | }
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144 |
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145 | return (cLocalSecs - cUtcSecs) * INT64_C(1000000000);
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146 | }
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147 |
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148 |
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149 | /**
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150 | * Gets the current delta between UTC and local time.
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151 | *
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152 | * @code
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153 | * RTTIMESPEC LocalTime;
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154 | * RTTimeSpecAddNano(RTTimeNow(&LocalTime), RTTimeLocalDeltaNano());
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155 | * @endcode
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156 | *
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157 | * @returns Returns the nanosecond delta between UTC and local time.
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158 | */
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159 | RTDECL(int64_t) RTTimeLocalDeltaNano(void)
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160 | {
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161 | RTTIMESPEC Time;
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162 | return rtTimeLocalUTCOffset(RTTimeNow(&Time), true /* current time, skip fallback */);
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163 | }
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164 |
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165 |
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166 | /**
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167 | * Gets the delta between UTC and local time at the given time.
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168 | *
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169 | * @code
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170 | * RTTIMESPEC LocalTime;
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171 | * RTTimeNow(&LocalTime);
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172 | * RTTimeSpecAddNano(&LocalTime, RTTimeLocalDeltaNanoFor(&LocalTime));
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173 | * @endcode
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174 | *
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175 | * @param pTimeSpec The time spec giving the time to get the delta for.
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176 | * @returns Returns the nanosecond delta between UTC and local time.
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177 | */
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178 | RTDECL(int64_t) RTTimeLocalDeltaNanoFor(PCRTTIMESPEC pTimeSpec)
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179 | {
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180 | AssertPtr(pTimeSpec);
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181 | return rtTimeLocalUTCOffset(pTimeSpec, false /* current time, skip fallback */);
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182 | }
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183 |
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184 |
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185 | /**
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186 | * Explodes a time spec to the localized timezone.
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187 | *
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188 | * @returns pTime.
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189 | * @param pTime Where to store the exploded time.
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190 | * @param pTimeSpec The time spec to exploded. (UTC)
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191 | */
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192 | RTDECL(PRTTIME) RTTimeLocalExplode(PRTTIME pTime, PCRTTIMESPEC pTimeSpec)
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193 | {
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194 | RTTIMESPEC LocalTime = *pTimeSpec;
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195 | int64_t cNsUtcOffset = rtTimeLocalUTCOffset(&LocalTime, true /* current time, skip fallback */);
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196 | RTTimeSpecAddNano(&LocalTime, cNsUtcOffset);
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197 | pTime = RTTimeExplode(pTime, &LocalTime);
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198 | if (pTime)
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199 | {
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200 | pTime->fFlags = (pTime->fFlags & ~RTTIME_FLAGS_TYPE_MASK) | RTTIME_FLAGS_TYPE_LOCAL;
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201 | pTime->offUTC = cNsUtcOffset / RT_NS_1MIN;
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202 | }
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203 | return pTime;
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204 | }
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205 |
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