--- /dev/null
+// 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.
+//
+// Inspired by various parts of CoreRT, most notably TimeZoneInfo.WinRT.cs.
+
+#if !FULL_AOT_DESKTOP || WIN_PLATFORM
+
+using Microsoft.Win32;
+using System;
+using System.Collections;
+using System.Diagnostics;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Globalization;
+using System.Diagnostics.Contracts;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading;
+
+namespace System
+{
+ partial class TimeZoneInfo
+ {
+
+ internal struct SYSTEMTIME
+ {
+ internal ushort wYear;
+ internal ushort wMonth;
+ internal ushort wDayOfWeek;
+ internal ushort wDay;
+ internal ushort wHour;
+ internal ushort wMinute;
+ internal ushort wSecond;
+ internal ushort wMilliseconds;
+ }
+
+ [StructLayout (LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+ internal struct TIME_ZONE_INFORMATION
+ {
+ internal int Bias;
+ [MarshalAs (UnmanagedType.ByValTStr, SizeConst=32)]
+ internal string StandardName;
+ internal SYSTEMTIME StandardDate;
+ internal int StandardBias;
+ [MarshalAs (UnmanagedType.ByValTStr, SizeConst=32)]
+ internal string DaylightName;
+ internal SYSTEMTIME DaylightDate;
+ internal int DaylightBias;
+ }
+
+ [StructLayout (LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+ internal struct DYNAMIC_TIME_ZONE_INFORMATION
+ {
+ internal TIME_ZONE_INFORMATION TZI;
+ [MarshalAs(UnmanagedType.ByValTStr, SizeConst=128)]
+ internal string TimeZoneKeyName;
+ internal byte DynamicDaylightTimeDisabled;
+ }
+
+ internal const uint TIME_ZONE_ID_INVALID = 0xffffffff;
+ internal const uint ERROR_NO_MORE_ITEMS = 259;
+
+ [DllImport ("api-ms-win-core-timezone-l1-1-0.dll")]
+ internal extern static uint EnumDynamicTimeZoneInformation (uint dwIndex, out DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation);
+ [DllImport ("api-ms-win-core-timezone-l1-1-0.dll")]
+ internal extern static uint GetDynamicTimeZoneInformation (out DYNAMIC_TIME_ZONE_INFORMATION pTimeZoneInformation);
+ [DllImport ("api-ms-win-core-timezone-l1-1-0.dll")]
+ internal extern static uint GetDynamicTimeZoneInformationEffectiveYears(ref DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation, out uint FirstYear, out uint LastYear);
+ [DllImport ("api-ms-win-core-timezone-l1-1-0.dll")]
+ internal extern static bool GetTimeZoneInformationForYear(ushort wYear, ref DYNAMIC_TIME_ZONE_INFORMATION pdtzi, out TIME_ZONE_INFORMATION ptzi);
+
+ internal static AdjustmentRule CreateAdjustmentRuleFromTimeZoneInformation (ref DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation, DateTime startDate, DateTime endDate, int defaultBaseUtcOffset)
+ {
+ bool supportsDst = (timeZoneInformation.TZI.StandardDate.wMonth != 0);
+
+ if (!supportsDst) {
+ if (timeZoneInformation.TZI.Bias == defaultBaseUtcOffset) {
+ // this rule will not contain any information to be used to adjust dates. just ignore it
+ return null;
+ }
+
+ return AdjustmentRule.CreateAdjustmentRule (
+ startDate,
+ endDate,
+ TimeSpan.Zero, // no daylight saving transition
+ TransitionTime.CreateFixedDateRule (DateTime.MinValue, 1, 1),
+ TransitionTime.CreateFixedDateRule (DateTime.MinValue.AddMilliseconds(1), 1, 1),
+ new TimeSpan(0, defaultBaseUtcOffset - timeZoneInformation.TZI.Bias, 0)); // Bias delta is all what we need from this rule
+ }
+
+ //
+ // Create an AdjustmentRule with TransitionTime objects
+ //
+ TransitionTime daylightTransitionStart;
+ if (!TransitionTimeFromTimeZoneInformation (timeZoneInformation, out daylightTransitionStart, true /* start date */)) {
+ return null;
+ }
+
+ TransitionTime daylightTransitionEnd;
+ if (!TransitionTimeFromTimeZoneInformation (timeZoneInformation, out daylightTransitionEnd, false /* end date */)) {
+ return null;
+ }
+
+ if (daylightTransitionStart.Equals(daylightTransitionEnd)) {
+ // this happens when the time zone does support DST but the OS has DST disabled
+ return null;
+ }
+
+ return AdjustmentRule.CreateAdjustmentRule (
+ startDate,
+ endDate,
+ new TimeSpan (0, -timeZoneInformation.TZI.DaylightBias, 0),
+ (TransitionTime) daylightTransitionStart,
+ (TransitionTime) daylightTransitionEnd,
+ new TimeSpan (0, defaultBaseUtcOffset - timeZoneInformation.TZI.Bias, 0));
+ }
+
+ //
+ // TransitionTimeFromTimeZoneInformation -
+ //
+ // Converts a TimeZoneInformation (REG_TZI_FORMAT struct) to a TransitionTime
+ //
+ // * when the argument 'readStart' is true the corresponding daylightTransitionTimeStart field is read
+ // * when the argument 'readStart' is false the corresponding dayightTransitionTimeEnd field is read
+ //
+ private static bool TransitionTimeFromTimeZoneInformation (DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation, out TransitionTime transitionTime, bool readStartDate)
+ {
+ //
+ // SYSTEMTIME -
+ //
+ // If the time zone does not support daylight saving time or if the caller needs
+ // to disable daylight saving time, the wMonth member in the SYSTEMTIME structure
+ // must be zero. If this date is specified, the DaylightDate value in the
+ // TIME_ZONE_INFORMATION structure must also be specified. Otherwise, the system
+ // assumes the time zone data is invalid and no changes will be applied.
+ //
+ bool supportsDst = (timeZoneInformation.TZI.StandardDate.wMonth != 0);
+
+ if (!supportsDst) {
+ transitionTime = default (TransitionTime);
+ return false;
+ }
+
+ //
+ // SYSTEMTIME -
+ //
+ // * FixedDateRule -
+ // If the Year member is not zero, the transition date is absolute; it will only occur one time
+ //
+ // * FloatingDateRule -
+ // To select the correct day in the month, set the Year member to zero, the Hour and Minute
+ // members to the transition time, the DayOfWeek member to the appropriate weekday, and the
+ // Day member to indicate the occurence of the day of the week within the month (first through fifth).
+ //
+ // Using this notation, specify the 2:00a.m. on the first Sunday in April as follows:
+ // Hour = 2,
+ // Month = 4,
+ // DayOfWeek = 0,
+ // Day = 1.
+ //
+ // Specify 2:00a.m. on the last Thursday in October as follows:
+ // Hour = 2,
+ // Month = 10,
+ // DayOfWeek = 4,
+ // Day = 5.
+ //
+ if (readStartDate) {
+ //
+ // read the "daylightTransitionStart"
+ //
+ if (timeZoneInformation.TZI.DaylightDate.wYear == 0) {
+ transitionTime = TransitionTime.CreateFloatingDateRule (
+ new DateTime (1, /* year */
+ 1, /* month */
+ 1, /* day */
+ timeZoneInformation.TZI.DaylightDate.wHour,
+ timeZoneInformation.TZI.DaylightDate.wMinute,
+ timeZoneInformation.TZI.DaylightDate.wSecond,
+ timeZoneInformation.TZI.DaylightDate.wMilliseconds),
+ timeZoneInformation.TZI.DaylightDate.wMonth,
+ timeZoneInformation.TZI.DaylightDate.wDay, /* Week 1-5 */
+ (DayOfWeek)timeZoneInformation.TZI.DaylightDate.wDayOfWeek);
+ } else {
+ transitionTime = TransitionTime.CreateFixedDateRule (
+ new DateTime (1, /* year */
+ 1, /* month */
+ 1, /* day */
+ timeZoneInformation.TZI.DaylightDate.wHour,
+ timeZoneInformation.TZI.DaylightDate.wMinute,
+ timeZoneInformation.TZI.DaylightDate.wSecond,
+ timeZoneInformation.TZI.DaylightDate.wMilliseconds),
+ timeZoneInformation.TZI.DaylightDate.wMonth,
+ timeZoneInformation.TZI.DaylightDate.wDay);
+ }
+ } else {
+ //
+ // read the "daylightTransitionEnd"
+ //
+ if (timeZoneInformation.TZI.StandardDate.wYear == 0) {
+ transitionTime = TransitionTime.CreateFloatingDateRule (
+ new DateTime (1, /* year */
+ 1, /* month */
+ 1, /* day */
+ timeZoneInformation.TZI.StandardDate.wHour,
+ timeZoneInformation.TZI.StandardDate.wMinute,
+ timeZoneInformation.TZI.StandardDate.wSecond,
+ timeZoneInformation.TZI.StandardDate.wMilliseconds),
+ timeZoneInformation.TZI.StandardDate.wMonth,
+ timeZoneInformation.TZI.StandardDate.wDay, /* Week 1-5 */
+ (DayOfWeek)timeZoneInformation.TZI.StandardDate.wDayOfWeek);
+ } else {
+ transitionTime = TransitionTime.CreateFixedDateRule (
+ new DateTime (1, /* year */
+ 1, /* month */
+ 1, /* day */
+ timeZoneInformation.TZI.StandardDate.wHour,
+ timeZoneInformation.TZI.StandardDate.wMinute,
+ timeZoneInformation.TZI.StandardDate.wSecond,
+ timeZoneInformation.TZI.StandardDate.wMilliseconds),
+ timeZoneInformation.TZI.StandardDate.wMonth,
+ timeZoneInformation.TZI.StandardDate.wDay);
+ }
+ }
+
+ return true;
+ }
+
+ internal static TimeZoneInfo TryCreateTimeZone (DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation)
+ {
+ uint firstYear = 0, lastYear = 0;
+ AdjustmentRule rule;
+ AdjustmentRule[] zoneRules = null;
+ int defaultBaseUtcOffset = timeZoneInformation.TZI.Bias;
+
+ if (String.IsNullOrEmpty (timeZoneInformation.TimeZoneKeyName))
+ return null;
+
+ //
+ // First get the adjustment rules
+ //
+
+ try {
+ if (GetDynamicTimeZoneInformationEffectiveYears (ref timeZoneInformation, out firstYear, out lastYear) == 0) {
+ firstYear = lastYear = 0;
+ }
+ } catch {
+ // If we don't have GetDynamicTimeZoneInformationEffectiveYears()
+ firstYear = lastYear = 0;
+ }
+
+ if (firstYear == lastYear) {
+ rule = CreateAdjustmentRuleFromTimeZoneInformation (ref timeZoneInformation, DateTime.MinValue.Date, DateTime.MaxValue.Date, defaultBaseUtcOffset);
+ if (rule != null)
+ zoneRules = new AdjustmentRule [1] { rule };
+ } else {
+ DYNAMIC_TIME_ZONE_INFORMATION dtzi = default (DYNAMIC_TIME_ZONE_INFORMATION);
+ List<AdjustmentRule> rules = new List<AdjustmentRule> ();
+ //
+ // First rule
+ //
+
+ if (!GetTimeZoneInformationForYear ((ushort) firstYear, ref timeZoneInformation, out dtzi.TZI))
+ return null;
+ rule = CreateAdjustmentRuleFromTimeZoneInformation (ref dtzi, DateTime.MinValue.Date, new DateTime ((int) firstYear, 12, 31), defaultBaseUtcOffset);
+ if (rule != null)
+ rules.Add (rule);
+
+ for (uint i = firstYear + 1; i < lastYear; i++) {
+ if (!GetTimeZoneInformationForYear ((ushort) i, ref timeZoneInformation, out dtzi.TZI))
+ return null;
+ rule = CreateAdjustmentRuleFromTimeZoneInformation (ref dtzi, new DateTime ((int) i, 1, 1), new DateTime ((int) i, 12, 31), defaultBaseUtcOffset);
+ if (rule != null)
+ rules.Add (rule);
+ }
+
+ //
+ // Last rule
+ //
+
+ if (!GetTimeZoneInformationForYear ((ushort) lastYear, ref timeZoneInformation, out dtzi.TZI))
+ return null;
+ rule = CreateAdjustmentRuleFromTimeZoneInformation (ref dtzi, new DateTime ((int) lastYear, 1, 1), DateTime.MaxValue.Date, defaultBaseUtcOffset);
+ if (rule != null)
+ rules.Add (rule);
+
+ if (rules.Count > 0)
+ zoneRules = rules.ToArray ();
+ }
+
+ return new TimeZoneInfo (
+ timeZoneInformation.TimeZoneKeyName,
+ new TimeSpan (0, -(timeZoneInformation.TZI.Bias), 0),
+ timeZoneInformation.TZI.StandardName, // we use the display name as the standared names
+ timeZoneInformation.TZI.StandardName,
+ timeZoneInformation.TZI.DaylightName,
+ zoneRules,
+ false);
+ }
+
+ internal static TimeZoneInfo GetLocalTimeZoneInfoWinRTFallback ()
+ {
+ try {
+ DYNAMIC_TIME_ZONE_INFORMATION dtzi;
+ var result = GetDynamicTimeZoneInformation (out dtzi);
+ if (result == TIME_ZONE_ID_INVALID)
+ return Utc;
+ TimeZoneInfo timeZoneInfo = TryCreateTimeZone (dtzi);
+ return timeZoneInfo != null ? timeZoneInfo : Utc;
+ } catch {
+ return Utc;
+ }
+ }
+
+ internal static TimeZoneInfo FindSystemTimeZoneByIdWinRTFallback (string id)
+ {
+ foreach (var tzi in GetSystemTimeZones ()) {
+ if (String.Compare (id, tzi.Id, StringComparison.Ordinal) == 0)
+ return tzi;
+ }
+
+ throw new TimeZoneNotFoundException ();
+ }
+
+ internal static List<TimeZoneInfo> GetSystemTimeZonesWinRTFallback ()
+ {
+ var result = new List<TimeZoneInfo> ();
+ try {
+ uint index = 0;
+ DYNAMIC_TIME_ZONE_INFORMATION dtzi;
+ while (EnumDynamicTimeZoneInformation (index++, out dtzi) != ERROR_NO_MORE_ITEMS) {
+ var timeZoneInfo = TryCreateTimeZone (dtzi);
+ if (timeZoneInfo != null)
+ result.Add (timeZoneInfo);
+ }
+ } catch {
+ // EnumDynamicTimeZoneInformation() might not be available.
+ }
+
+ if (result.Count == 0)
+ result.Add (Local);
+ return result;
+ }
+ }
+}
+
+#endif // !FULL_AOT_DESKTOP || WIN_PLATFORM
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