Merge pull request #1118 from Unity-Technologies/unity-master-fix-win32-timezone

Attempt to use Win32 APIs first to retreive current timezone (case 1076679)

Author: joncham

mcs/class/corlib/System/TimeZoneInfo.WinRT.cs

@@ -66,6 +66,8 @@ internal struct DYNAMIC_TIME_ZONE_INFORMATION
 		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 ("kernel32.dll", EntryPoint="GetDynamicTimeZoneInformation")]
+		internal extern static uint GetDynamicTimeZoneInformationWin32 (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")]
@@ -310,6 +312,24 @@ internal static TimeZoneInfo GetLocalTimeZoneInfoWinRTFallback ()
 				return timeZoneInfo != null ? timeZoneInfo : Utc;
 			} catch {
 				return Utc;
+
+			}
+		}
+
+		internal static string GetLocalTimeZoneKeyNameWin32Fallback ()
+		{
+			try {
+				DYNAMIC_TIME_ZONE_INFORMATION dtzi;
+				var result = GetDynamicTimeZoneInformationWin32 (out dtzi);
+				if (result == TIME_ZONE_ID_INVALID)
+					return null;
+				if (!string.IsNullOrEmpty(dtzi.TimeZoneKeyName))
+					return dtzi.TimeZoneKeyName;
+				else if (!string.IsNullOrEmpty(dtzi.TZI.StandardName))
+					return dtzi.TZI.StandardName;
+				return null;
+			} catch {
+				return null;
 			}
 		}
 

mcs/class/corlib/System/TimeZoneInfo.cs

@@ -162,6 +162,8 @@ static TimeZoneInfo CreateLocal ()
 				if (name == null)
 					name = (string)LocalZoneKey.GetValue ("StandardName"); // windows xp
 				name = TrimSpecial (name);
+				if (string.IsNullOrEmpty(name))
+					name = GetLocalTimeZoneKeyNameWin32Fallback();
 				if (name != null)
 					return TimeZoneInfo.FindSystemTimeZoneById (name);
 			} else if (IsWindows) {