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Diffstat (limited to 'src/mscorlib/src/System/CurrentTimeZone.cs')
| -rw-r--r-- | src/mscorlib/src/System/CurrentTimeZone.cs | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/CurrentTimeZone.cs b/src/mscorlib/src/System/CurrentTimeZone.cs new file mode 100644 index 0000000000..f015c05b33 --- /dev/null +++ b/src/mscorlib/src/System/CurrentTimeZone.cs @@ -0,0 +1,310 @@ +// Licensed to the .NET Foundation under one or more agreements. +// The .NET Foundation licenses this file to you under the MIT license. +// See the LICENSE file in the project root for more information. + +/*============================================================ +** +** Class: CurrentTimeZone +** +** +** Purpose: +** This class represents the current system timezone. It is +** the only meaningful implementation of the TimeZone class +** available in this version. +** +** The only TimeZone that we support in version 1 is the +** CurrentTimeZone as determined by the system timezone. +** +** +============================================================*/ +namespace System { + using System; + using System.Diagnostics.Contracts; + using System.Text; + using System.Threading; + using System.Collections; + using System.Globalization; + using System.Runtime.CompilerServices; + using System.Runtime.Versioning; + + // + // Currently, this is the only supported timezone. + // The values of the timezone is from the current system timezone setting in the + // control panel. + // +#if FEATURE_CORECLR + [Obsolete("System.CurrentSystemTimeZone has been deprecated. Please investigate the use of System.TimeZoneInfo.Local instead.")] +#endif + [Serializable] + internal class CurrentSystemTimeZone : TimeZone { + // <BUGBUG>BUGBUG : + // One problem is when user changes the current timezone. We + // are not able to update currentStandardName/currentDaylightName/ + // currentDaylightChanges. + // We need WM_TIMECHANGE to do this or use + // RegNotifyChangeKeyValue() to monitor </BUGBUG> + // + private const long TicksPerMillisecond = 10000; + private const long TicksPerSecond = TicksPerMillisecond * 1000; + private const long TicksPerMinute = TicksPerSecond * 60; + + // The per-year information is cached in in this instance value. As a result it can + // be cleaned up by CultureInfo.ClearCachedData, which will clear the instance of this object + private Hashtable m_CachedDaylightChanges = new Hashtable(); + + // Standard offset in ticks to the Universal time if + // no daylight saving is in used. + // E.g. the offset for PST (Pacific Standard time) should be -8 * 60 * 60 * 1000 * 10000. + // (1 millisecond = 10000 ticks) + private long m_ticksOffset; + private String m_standardName; + private String m_daylightName; + + [System.Security.SecuritySafeCritical] // auto-generated + internal CurrentSystemTimeZone() { + m_ticksOffset = nativeGetTimeZoneMinuteOffset() * TicksPerMinute; + m_standardName = null; + m_daylightName = null; + } + + public override String StandardName { + [System.Security.SecuritySafeCritical] // auto-generated + get { + if (m_standardName == null) { + m_standardName = nativeGetStandardName(); + } + return (m_standardName); + } + } + + public override String DaylightName { + [System.Security.SecuritySafeCritical] // auto-generated + get { + if (m_daylightName == null) { + m_daylightName = nativeGetDaylightName(); + if (m_daylightName == null) { + m_daylightName = this.StandardName; + } + } + return (m_daylightName); + } + } + + internal long GetUtcOffsetFromUniversalTime(DateTime time, ref Boolean isAmbiguousLocalDst) { + // Get the daylight changes for the year of the specified time. + TimeSpan offset = new TimeSpan(m_ticksOffset); + DaylightTime daylightTime = GetDaylightChanges(time.Year); + isAmbiguousLocalDst= false; + + if (daylightTime == null || daylightTime.Delta.Ticks == 0) { + return offset.Ticks; + } + + // The start and end times represent the range of universal times that are in DST for that year. + // Within that there is an ambiguous hour, usually right at the end, but at the beginning in + // the unusual case of a negative daylight savings delta. + DateTime startTime = daylightTime.Start - offset; + DateTime endTime = daylightTime.End - offset - daylightTime.Delta; + DateTime ambiguousStart; + DateTime ambiguousEnd; + if (daylightTime.Delta.Ticks > 0) { + ambiguousStart = endTime - daylightTime.Delta; + ambiguousEnd = endTime; + } else { + ambiguousStart = startTime; + ambiguousEnd = startTime - daylightTime.Delta; + } + + Boolean isDst = false; + if (startTime > endTime) { + // In southern hemisphere, the daylight saving time starts later in the year, and ends in the beginning of next year. + // Note, the summer in the southern hemisphere begins late in the year. + isDst = (time < endTime || time >= startTime); + } + else { + // In northern hemisphere, the daylight saving time starts in the middle of the year. + isDst = (time>=startTime && time<endTime); + } + if (isDst) { + offset += daylightTime.Delta; + + // See if the resulting local time becomes ambiguous. This must be captured here or the + // DateTime will not be able to round-trip back to UTC accurately. + if (time >= ambiguousStart && time < ambiguousEnd ) { + isAmbiguousLocalDst = true; + } + } + return offset.Ticks; + } + + public override DateTime ToLocalTime(DateTime time) { + if (time.Kind == DateTimeKind.Local) { + return time; + } + Boolean isAmbiguousLocalDst = false; + Int64 offset = GetUtcOffsetFromUniversalTime(time, ref isAmbiguousLocalDst); + long tick = time.Ticks + offset; + if (tick>DateTime.MaxTicks) { + return new DateTime(DateTime.MaxTicks, DateTimeKind.Local); + } + if (tick<DateTime.MinTicks) { + return new DateTime(DateTime.MinTicks, DateTimeKind.Local); + } + return new DateTime(tick, DateTimeKind.Local, isAmbiguousLocalDst); + } + + // Private object for locking instead of locking on a public type for SQL reliability work. + private static Object s_InternalSyncObject; + private static Object InternalSyncObject { + get { + if (s_InternalSyncObject == null) { + Object o = new Object(); + Interlocked.CompareExchange<Object>(ref s_InternalSyncObject, o, null); + } + return s_InternalSyncObject; + } + } + + + [System.Security.SecuritySafeCritical] // auto-generated + public override DaylightTime GetDaylightChanges(int year) { + if (year < 1 || year > 9999) { + throw new ArgumentOutOfRangeException("year", Environment.GetResourceString("ArgumentOutOfRange_Range", 1, 9999)); + } + Contract.EndContractBlock(); + + Object objYear = (Object)year; + + if (!m_CachedDaylightChanges.Contains(objYear)) { + lock (InternalSyncObject) { + + if (!m_CachedDaylightChanges.Contains(objYear)) { + + // + // rawData is an array of 17 short (16 bit) numbers. + // The first 8 numbers contains the + // year/month/day/dayOfWeek/hour/minute/second/millisecond for the starting time of daylight saving time. + // The next 8 numbers contains the + // year/month/day/dayOfWeek/hour/minute/second/millisecond for the ending time of daylight saving time. + // The last short number is the delta to the standard offset in minutes. + // + short[] rawData = nativeGetDaylightChanges(year); + + if (rawData == null) { + // + // If rawData is null, it means that daylight saving time is not used + // in this timezone. So keep currentDaylightChanges as the empty array. + // + m_CachedDaylightChanges.Add(objYear, new DaylightTime(DateTime.MinValue, DateTime.MinValue, TimeSpan.Zero)); + } else { + DateTime start; + DateTime end; + TimeSpan delta; + + // + // Store the start of daylight saving time. + // + + start = GetDayOfWeek(year, (rawData[0] != 0), rawData[1], rawData[2], + rawData[3], + rawData[4], rawData[5], rawData[6], rawData[7]); + + // + // Store the end of daylight saving time. + // + end = GetDayOfWeek(year, (rawData[8] != 0), rawData[9], rawData[10], + rawData[11], + rawData[12], rawData[13], rawData[14], rawData[15]); + + delta = new TimeSpan(rawData[16] * TicksPerMinute); + DaylightTime currentDaylightChanges = new DaylightTime(start, end, delta); + m_CachedDaylightChanges.Add(objYear, currentDaylightChanges); + } + } + } + } + + DaylightTime result = (DaylightTime)m_CachedDaylightChanges[objYear]; + + return result; + } + + public override TimeSpan GetUtcOffset(DateTime time) { + if (time.Kind == DateTimeKind.Utc) { + return TimeSpan.Zero; + } + else { + return new TimeSpan(TimeZone.CalculateUtcOffset(time, GetDaylightChanges(time.Year)).Ticks + m_ticksOffset); + } + } + + // + // Return the (numberOfSunday)th day of week in a particular year/month. + // + private static DateTime GetDayOfWeek(int year, bool fixedDate, int month, int targetDayOfWeek, int numberOfSunday, int hour, int minute, int second, int millisecond) { + DateTime time; + + if (fixedDate) { + // + // Create a Fixed-Date transition time based on the supplied parameters + // For Fixed-Dated transition times, the 'numberOfSunday' parameter actually + // represents the day of the month. + // + + // if the day is out of range for the month then use the last day of the month + int day = DateTime.DaysInMonth(year, month); + + time = new DateTime(year, month, (day < numberOfSunday) ? day : numberOfSunday, + hour, minute, second, millisecond, DateTimeKind.Local); + } + else if (numberOfSunday <= 4) { + // + // Get the (numberOfSunday)th Sunday. + // + + time = new DateTime(year, month, 1, hour, minute, second, millisecond, DateTimeKind.Local); + + int dayOfWeek = (int)time.DayOfWeek; + int delta = targetDayOfWeek - dayOfWeek; + if (delta < 0) { + delta += 7; + } + delta += 7 * (numberOfSunday - 1); + + if (delta > 0) { + time = time.AddDays(delta); + } + } else { + // + // If numberOfSunday is greater than 4, we will get the last sunday. + // + Calendar cal = GregorianCalendar.GetDefaultInstance(); + time = new DateTime(year, month, cal.GetDaysInMonth(year, month), hour, minute, second, millisecond, DateTimeKind.Local); + // This is the day of week for the last day of the month. + int dayOfWeek = (int)time.DayOfWeek; + int delta = dayOfWeek - targetDayOfWeek; + if (delta < 0) { + delta += 7; + } + + if (delta > 0) { + time = time.AddDays(-delta); + } + } + return (time); + } + + [System.Security.SecurityCritical] // auto-generated + [MethodImplAttribute(MethodImplOptions.InternalCall)] + internal extern static int nativeGetTimeZoneMinuteOffset(); + [System.Security.SecurityCritical] // auto-generated + [MethodImplAttribute(MethodImplOptions.InternalCall)] + internal extern static String nativeGetDaylightName(); + [System.Security.SecurityCritical] // auto-generated + [MethodImplAttribute(MethodImplOptions.InternalCall)] + internal extern static String nativeGetStandardName(); + [System.Security.SecurityCritical] // auto-generated + [MethodImplAttribute(MethodImplOptions.InternalCall)] + internal extern static short[] nativeGetDaylightChanges(int year); + } // class CurrentSystemTimeZone +} |