Implements TimeZoneInfo.Local for Windows

Fixes #2791, contributed by Jonathan Shore <jonathan.shore@gmail.com>

diff --git a/mcs/class/System.Core/System/TimeZoneInfo.cs b/mcs/class/System.Core/System/TimeZoneInfo.cs
index 3d83e6e727f11e97950ea3f4d2c668c48d790281..47315bb1ce27600002c64da96953df2915d30fe2 100644 (file)
--- a/mcs/class/System.Core/System/TimeZoneInfo.cs
+++ b/mcs/class/System.Core/System/TimeZoneInfo.cs
@@ -102,7 +102,15 @@ namespace System
                                                }
                                        }
 #else
-                                       throw new TimeZoneNotFoundException ();
+                                       if (IsWindows && LocalZoneKey != null) {
+                                               string name = (string)LocalZoneKey.GetValue ("TimeZoneKeyName");
+                                               name = TrimSpecial (name);
+                                               if (name != null)
+                                                       local = TimeZoneInfo.FindSystemTimeZoneById (name);
+                                       }
+                                       
+                                       if (local == null)
+                                               throw new TimeZoneNotFoundException ();
 #endif
                                }
                                return local;
@@ -144,20 +152,55 @@ namespace System
                private AdjustmentRule [] adjustmentRules;
 
 #if !NET_2_1
+               /// <summary>
+               /// Determine whether windows of not (taken Stephane Delcroix's code)
+               /// </summary>
+               private static bool IsWindows
+               {
+                       get {
+                               int platform = (int) Environment.OSVersion.Platform;
+                               return ((platform != 4) && (platform != 6) && (platform != 128));
+                       }
+               }
+               
+               /// <summary>
+               /// Needed to trim misc garbage in MS registry keys
+               /// </summary>
+               private static string TrimSpecial (string str)
+               {
+                       var Istart = 0;
+                       while (Istart < str.Length && !char.IsLetterOrDigit(str[Istart])) Istart++;
+                       var Iend = str.Length - 1;
+                       while (Iend > Istart && !char.IsLetterOrDigit(str[Iend])) Iend--;
+                       
+                       return str.Substring (Istart, Iend-Istart+1);
+               }
+               
                static RegistryKey timeZoneKey = null;
-               static bool timeZoneKeySet = false;
                static RegistryKey TimeZoneKey {
                        get {
-                               if (!timeZoneKeySet) {
-                                       int p = (int) Environment.OSVersion.Platform;
-                                       /* Only use the registry on non-Unix platforms. */
-                                       if ((p != 4) && (p != 6) && (p != 128))
-                                               timeZoneKey = Registry.LocalMachine.OpenSubKey (
-                                                       "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
-                                                       false);
-                                       timeZoneKeySet = true;
-                               }
-                               return timeZoneKey;
+                               if (timeZoneKey != null)
+                                       return timeZoneKey;
+                               if (!IsWindows)
+                                       return null;
+                               
+                               return timeZoneKey = Registry.LocalMachine.OpenSubKey (
+                                       "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
+                                       false);
+                       }
+               }
+               
+               static RegistryKey localZoneKey = null;
+               static RegistryKey LocalZoneKey {
+                       get {
+                               if (localZoneKey != null)
+                                       return localZoneKey;
+                               
+                               if (!IsWindows)
+                                       return null;
+                               
+                               return localZoneKey = Registry.LocalMachine.OpenSubKey (
+                                       "SYSTEM\\CurrentControlSet\\Control\\TimeZoneInformation", false);
                        }
                }
 #endif