mcs/class/System.Core/System/TimeZoneInfo.cs

   1 /*
   2  * System.TimeZoneInfo
   3  *
   4  * Author(s)
   5  *      Stephane Delcroix <stephane@delcroix.org>
   6  *
   7  * Copyright 2011 Xamarin Inc.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining
  10  * a copy of this software and associated documentation files (the
  11  * "Software"), to deal in the Software without restriction, including
  12  * without limitation the rights to use, copy, modify, merge, publish,
  13  * distribute, sublicense, and/or sell copies of the Software, and to
  14  * permit persons to whom the Software is furnished to do so, subject to
  15  * the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be
  18  * included in all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27  */
  28
  29 using System;
  30 using System.Runtime.CompilerServices;
  31
  32 #if !INSIDE_CORLIB && (NET_4_0 || MOONLIGHT || MOBILE)
  33
  34 [assembly:TypeForwardedTo (typeof(TimeZoneInfo))]
  35
  36 #elif (INSIDE_CORLIB && (NET_4_0 || MOONLIGHT || MOBILE)) || (!INSIDE_CORLIB && (NET_3_5 && !NET_4_0 && !MOBILE))
  37
  38 using System.Collections.Generic;
  39 using System.Collections.ObjectModel;
  40 using System.Runtime.Serialization;
  41 using System.Text;
  42
  43 #if LIBC || MONODROID
  44 using System.IO;
  45 using Mono;
  46 #endif
  47
  48 using Microsoft.Win32;
  49
  50 namespace System
  51 {
  52 #if NET_4_0
  53         [TypeForwardedFrom (Consts.AssemblySystemCore_3_5)]
  54 #elif MOONLIGHT || MOBILE
  55         [TypeForwardedFrom (Consts.AssemblySystem_Core)]
  56 #endif
  57         [SerializableAttribute]
  58         public sealed partial class TimeZoneInfo : IEquatable<TimeZoneInfo>, ISerializable, IDeserializationCallback
  59         {
  60                 TimeSpan baseUtcOffset;
  61                 public TimeSpan BaseUtcOffset {
  62                         get { return baseUtcOffset; }
  63                 }
  64
  65                 string daylightDisplayName;
  66                 public string DaylightName {
  67                         get {
  68                                 if (disableDaylightSavingTime)
  69                                         return String.Empty;
  70                                 return daylightDisplayName;
  71                         }
  72                 }
  73
  74                 string displayName;
  75                 public string DisplayName {
  76                         get { return displayName; }
  77                 }
  78
  79                 string id;
  80                 public string Id {
  81                         get { return id; }
  82                 }
  83
  84                 static TimeZoneInfo local;
  85                 public static TimeZoneInfo Local {
  86                         get {
  87                                 if (local == null) {
  88 #if MONODROID
  89                                         local = ZoneInfoDB.Default;
  90 #elif LIBC
  91                                         try {
  92                                                 local = FindSystemTimeZoneByFileName ("Local", "/etc/localtime");
  93                                         } catch {
  94                                                 try {
  95                                                         local = FindSystemTimeZoneByFileName ("Local", Path.Combine (TimeZoneDirectory, "localtime"));
  96                                                 } catch {
  97                                                         throw new TimeZoneNotFoundException ();
  98                                                 }
  99                                         }
 100 #else
 101                                         throw new TimeZoneNotFoundException ();
 102 #endif
 103                                 }
 104                                 return local;
 105                         }
 106                 }
 107
 108                 string standardDisplayName;
 109                 public string StandardName {
 110                         get { return standardDisplayName; }
 111                 }
 112
 113                 bool disableDaylightSavingTime;
 114                 public bool SupportsDaylightSavingTime {
 115                         get  { return !disableDaylightSavingTime; }
 116                 }
 117
 118                 static TimeZoneInfo utc;
 119                 public static TimeZoneInfo Utc {
 120                         get {
 121                                 if (utc == null)
 122                                         utc = CreateCustomTimeZone ("UTC", new TimeSpan (0), "UTC", "UTC");
 123                                 return utc;
 124                         }
 125                 }
 126 #if LIBC
 127                 static string timeZoneDirectory = null;
 128                 static string TimeZoneDirectory {
 129                         get {
 130                                 if (timeZoneDirectory == null)
 131                                         timeZoneDirectory = "/usr/share/zoneinfo";
 132                                 return timeZoneDirectory;
 133                         }
 134                         set {
 135                                 ClearCachedData ();
 136                                 timeZoneDirectory = value;
 137                         }
 138                 }
 139 #endif
 140                 private AdjustmentRule [] adjustmentRules;
 141
 142 #if !NET_2_1
 143                 static RegistryKey timeZoneKey = null;
 144                 static bool timeZoneKeySet = false;
 145                 static RegistryKey TimeZoneKey {
 146                         get {
 147                                 if (!timeZoneKeySet) {
 148                                         int p = (int) Environment.OSVersion.Platform;
 149                                         /* Only use the registry on non-Unix platforms. */
 150                                         if ((p != 4) && (p != 6) && (p != 128))
 151                                                 timeZoneKey = Registry.LocalMachine.OpenSubKey (
 152                                                         "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
 153                                                         false);
 154                                         timeZoneKeySet = true;
 155                                 }
 156                                 return timeZoneKey;
 157                         }
 158                 }
 159 #endif
 160
 161                 public static void ClearCachedData ()
 162                 {
 163                         local = null;
 164                         utc = null;
 165                         systemTimeZones = null;
 166                 }
 167
 168                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 169                 {
 170                         return ConvertTime (dateTime, TimeZoneInfo.Local, destinationTimeZone);
 171                 }
 172
 173                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)
 174                 {
 175                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 176                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 177
 178                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 179                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 180
 181                         if (sourceTimeZone.IsInvalidTime (dateTime))
 182                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 183
 184                         if (sourceTimeZone == null)
 185                                 throw new ArgumentNullException ("sourceTimeZone");
 186
 187                         if (destinationTimeZone == null)
 188                                 throw new ArgumentNullException ("destinationTimeZone");
 189
 190                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone == TimeZoneInfo.Local && destinationTimeZone == TimeZoneInfo.Local)
 191                                 return dateTime;
 192
 193                         DateTime utc = ConvertTimeToUtc (dateTime);
 194
 195                         if (destinationTimeZone == TimeZoneInfo.Utc)
 196                                 return utc;
 197
 198                         return ConvertTimeFromUtc (utc, destinationTimeZone);
 199
 200                 }
 201
 202                 public static DateTimeOffset ConvertTime (DateTimeOffset dateTimeOffset, TimeZoneInfo destinationTimeZone)
 203                 {
 204                         throw new NotImplementedException ();
 205                 }
 206
 207                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string destinationTimeZoneId)
 208                 {
 209                         return ConvertTime (dateTime, FindSystemTimeZoneById (destinationTimeZoneId));
 210                 }
 211
 212                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string sourceTimeZoneId, string destinationTimeZoneId)
 213                 {
 214                         return ConvertTime (dateTime, FindSystemTimeZoneById (sourceTimeZoneId), FindSystemTimeZoneById (destinationTimeZoneId));
 215                 }
 216
 217                 public static DateTimeOffset ConvertTimeBySystemTimeZoneId (DateTimeOffset dateTimeOffset, string destinationTimeZoneId)
 218                 {
 219                         return ConvertTime (dateTimeOffset, FindSystemTimeZoneById (destinationTimeZoneId));
 220                 }
 221
 222                 private DateTime ConvertTimeFromUtc (DateTime dateTime)
 223                 {
 224                         if (dateTime.Kind == DateTimeKind.Local)
 225                                 throw new ArgumentException ("Kind property of dateTime is Local");
 226
 227                         if (this == TimeZoneInfo.Utc)
 228                                 return DateTime.SpecifyKind (dateTime, DateTimeKind.Utc);
 229
 230                         //FIXME: do not rely on DateTime implementation !
 231                         if (this == TimeZoneInfo.Local)
 232                                 return DateTime.SpecifyKind (dateTime.ToLocalTime (), DateTimeKind.Unspecified);
 233
 234                         AdjustmentRule rule = GetApplicableRule (dateTime);
 235
 236                         if (rule != null && IsDaylightSavingTime (DateTime.SpecifyKind (dateTime, DateTimeKind.Utc)))
 237                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset + rule.DaylightDelta , DateTimeKind.Unspecified);
 238                         else
 239                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset, DateTimeKind.Unspecified);
 240                 }
 241
 242                 public static DateTime ConvertTimeFromUtc (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 243                 {
 244                         if (destinationTimeZone == null)
 245                                 throw new ArgumentNullException ("destinationTimeZone");
 246
 247                         return destinationTimeZone.ConvertTimeFromUtc (dateTime);
 248                 }
 249
 250                 public static DateTime ConvertTimeToUtc (DateTime dateTime)
 251                 {
 252                         if (dateTime.Kind == DateTimeKind.Utc)
 253                                 return dateTime;
 254
 255                         //FIXME: do not rely on DateTime implementation !
 256                         return DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc);
 257                 }
 258
 259                 public static DateTime ConvertTimeToUtc (DateTime dateTime, TimeZoneInfo sourceTimeZone)
 260                 {
 261                         if (sourceTimeZone == null)
 262                                 throw new ArgumentNullException ("sourceTimeZone");
 263
 264                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 265                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 266
 267                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 268                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 269
 270                         if (sourceTimeZone.IsInvalidTime (dateTime))
 271                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 272
 273                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone == TimeZoneInfo.Utc)
 274                                 return dateTime;
 275
 276                         if (dateTime.Kind == DateTimeKind.Utc)
 277                                 return dateTime;
 278
 279                         if (dateTime.Kind == DateTimeKind.Local)
 280                                 return ConvertTimeToUtc (dateTime);
 281
 282                         if (sourceTimeZone.IsAmbiguousTime (dateTime) || !sourceTimeZone.IsDaylightSavingTime (dateTime))
 283                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 284                         else {
 285                                 AdjustmentRule rule = sourceTimeZone.GetApplicableRule (dateTime);
 286                                 if (rule != null)
 287                                         return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset - rule.DaylightDelta, DateTimeKind.Utc);
 288                                 else
 289                                         return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 290                         }
 291                 }
 292
 293                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName)
 294                 {
 295                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, null, null, true);
 296                 }
 297
 298                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules)
 299                 {
 300                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, false);
 301                 }
 302
 303                 public static TimeZoneInfo CreateCustomTimeZone ( string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 304                 {
 305                         return new TimeZoneInfo (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, disableDaylightSavingTime);
 306                 }
 307
 308                 public bool Equals (TimeZoneInfo other)
 309                 {
 310                         if (other == null)
 311                                 return false;
 312
 313                         return other.Id == this.Id && HasSameRules (other);
 314                 }
 315
 316                 public static TimeZoneInfo FindSystemTimeZoneById (string id)
 317                 {
 318                         //FIXME: this method should check for cached values in systemTimeZones
 319                         if (id == null)
 320                                 throw new ArgumentNullException ("id");
 321 #if !NET_2_1
 322                         if (TimeZoneKey != null)
 323                         {
 324                                 RegistryKey key = TimeZoneKey.OpenSubKey (id, false);
 325                                 if (key == null)
 326                                         throw new TimeZoneNotFoundException ();
 327                                 return FromRegistryKey(id, key);
 328                         }
 329 #endif
 330 #if MONODROID
 331                         return ZoneInfoDB.GetTimeZone (id);
 332 #elif LIBC
 333                         // Local requires special logic that already exists in the Local property (bug #326)
 334                         if (id == "Local")
 335                                 return Local;
 336                         string filepath = Path.Combine (TimeZoneDirectory, id);
 337                         return FindSystemTimeZoneByFileName (id, filepath);
 338 #else
 339                         throw new NotImplementedException ();
 340 #endif
 341                 }
 342
 343 #if LIBC
 344                 const int BUFFER_SIZE = 16384; //Big enough for any tz file (on Oct 2008, all tz files are under 10k)
 345                 private static TimeZoneInfo FindSystemTimeZoneByFileName (string id, string filepath)
 346                 {
 347                         if (!File.Exists (filepath))
 348                                 throw new TimeZoneNotFoundException ();
 349
 350                         byte [] buffer = new byte [BUFFER_SIZE];
 351                         int length;
 352                         using (FileStream stream = File.OpenRead (filepath)) {
 353                                 length = stream.Read (buffer, 0, BUFFER_SIZE);
 354                         }
 355
 356                         if (!ValidTZFile (buffer, length))
 357                                 throw new InvalidTimeZoneException ("TZ file too big for the buffer");
 358
 359                         try {
 360                                 return ParseTZBuffer (id, buffer, length);
 361                         } catch (Exception e) {
 362                                 throw new InvalidTimeZoneException (e.Message);
 363                         }
 364                 }
 365 #endif
 366
 367 #if !NET_2_1
 368                 private static TimeZoneInfo FromRegistryKey (string id, RegistryKey key)
 369                 {
 370                         byte [] reg_tzi = (byte []) key.GetValue ("TZI");
 371
 372                         if (reg_tzi == null)
 373                                 throw new InvalidTimeZoneException ();
 374
 375                         int bias = BitConverter.ToInt32 (reg_tzi, 0);
 376                         TimeSpan baseUtcOffset = new TimeSpan (0, -bias, 0);
 377
 378                         string display_name = (string) key.GetValue ("Display");
 379                         string standard_name = (string) key.GetValue ("Std");
 380                         string daylight_name = (string) key.GetValue ("Dlt");
 381
 382                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 383
 384                         RegistryKey dst_key = key.OpenSubKey ("Dynamic DST", false);
 385                         if (dst_key != null) {
 386                                 int first_year = (int) dst_key.GetValue ("FirstEntry");
 387                                 int last_year = (int) dst_key.GetValue ("LastEntry");
 388                                 int year;
 389
 390                                 for (year=first_year; year<=last_year; year++) {
 391                                         byte [] dst_tzi = (byte []) dst_key.GetValue (year.ToString ());
 392                                         if (dst_tzi != null) {
 393                                                 int start_year = year == first_year ? 1 : year;
 394                                                 int end_year = year == last_year ? 9999 : year;
 395                                                 ParseRegTzi(adjustmentRules, start_year, end_year, dst_tzi);
 396                                         }
 397                                 }
 398                         }
 399                         else
 400                                 ParseRegTzi(adjustmentRules, 1, 9999, reg_tzi);
 401
 402                         return CreateCustomTimeZone (id, baseUtcOffset, display_name, standard_name, daylight_name, ValidateRules (adjustmentRules).ToArray ());
 403                 }
 404
 405                 private static void ParseRegTzi (List<AdjustmentRule> adjustmentRules, int start_year, int end_year, byte [] buffer)
 406                 {
 407                         //int standard_bias = BitConverter.ToInt32 (buffer, 4); /* not sure how to handle this */
 408                         int daylight_bias = BitConverter.ToInt32 (buffer, 8);
 409
 410                         int standard_year = BitConverter.ToInt16 (buffer, 12);
 411                         int standard_month = BitConverter.ToInt16 (buffer, 14);
 412                         int standard_dayofweek = BitConverter.ToInt16 (buffer, 16);
 413                         int standard_day = BitConverter.ToInt16 (buffer, 18);
 414                         int standard_hour = BitConverter.ToInt16 (buffer, 20);
 415                         int standard_minute = BitConverter.ToInt16 (buffer, 22);
 416                         int standard_second = BitConverter.ToInt16 (buffer, 24);
 417                         int standard_millisecond = BitConverter.ToInt16 (buffer, 26);
 418
 419                         int daylight_year = BitConverter.ToInt16 (buffer, 28);
 420                         int daylight_month = BitConverter.ToInt16 (buffer, 30);
 421                         int daylight_dayofweek = BitConverter.ToInt16 (buffer, 32);
 422                         int daylight_day = BitConverter.ToInt16 (buffer, 34);
 423                         int daylight_hour = BitConverter.ToInt16 (buffer, 36);
 424                         int daylight_minute = BitConverter.ToInt16 (buffer, 38);
 425                         int daylight_second = BitConverter.ToInt16 (buffer, 40);
 426                         int daylight_millisecond = BitConverter.ToInt16 (buffer, 42);
 427
 428                         if (standard_month == 0 || daylight_month == 0)
 429                                 return;
 430
 431                         DateTime start_date;
 432                         DateTime start_timeofday = new DateTime (1, 1, 1, daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 433                         TransitionTime start_transition_time;
 434
 435                         if (daylight_year == 0) {
 436                                 start_date = new DateTime (start_year, 1, 1);
 437                                 start_transition_time = TransitionTime.CreateFloatingDateRule (
 438                                         start_timeofday, daylight_month, daylight_day,
 439                                         (DayOfWeek) daylight_dayofweek);
 440                         }
 441                         else {
 442                                 start_date = new DateTime (daylight_year, daylight_month, daylight_day,
 443                                         daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 444                                 start_transition_time = TransitionTime.CreateFixedDateRule (
 445                                         start_timeofday, daylight_month, daylight_day);
 446                         }
 447
 448                         DateTime end_date;
 449                         DateTime end_timeofday = new DateTime (1, 1, 1, standard_hour, standard_minute, standard_second, standard_millisecond);
 450                         TransitionTime end_transition_time;
 451
 452                         if (standard_year == 0) {
 453                                 end_date = new DateTime (end_year, 12, 31);
 454                                 end_transition_time = TransitionTime.CreateFloatingDateRule (
 455                                         end_timeofday, standard_month, standard_day,
 456                                         (DayOfWeek) standard_dayofweek);
 457                         }
 458                         else {
 459                                 end_date = new DateTime (standard_year, standard_month, standard_day,
 460                                         standard_hour, standard_minute, standard_second, standard_millisecond);
 461                                 end_transition_time = TransitionTime.CreateFixedDateRule (
 462                                         end_timeofday, standard_month, standard_day);
 463                         }
 464
 465                         TimeSpan daylight_delta = new TimeSpan(0, -daylight_bias, 0);
 466
 467                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (
 468                                 start_date, end_date, daylight_delta,
 469                                 start_transition_time, end_transition_time));
 470                 }
 471 #endif
 472
 473                 public static TimeZoneInfo FromSerializedString (string source)
 474                 {
 475                         throw new NotImplementedException ();
 476                 }
 477
 478                 public AdjustmentRule [] GetAdjustmentRules ()
 479                 {
 480                         if (disableDaylightSavingTime)
 481                                 return new AdjustmentRule [0];
 482                         else
 483                                 return (AdjustmentRule []) adjustmentRules.Clone ();
 484                 }
 485
 486                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTime dateTime)
 487                 {
 488                         if (!IsAmbiguousTime (dateTime))
 489                                 throw new ArgumentException ("dateTime is not an ambiguous time");
 490
 491                         AdjustmentRule rule = GetApplicableRule (dateTime);
 492                         if (rule != null)
 493                                 return new TimeSpan[] {baseUtcOffset, baseUtcOffset + rule.DaylightDelta};
 494                         else
 495                                 return new TimeSpan[] {baseUtcOffset, baseUtcOffset};
 496                 }
 497
 498                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTimeOffset dateTimeOffset)
 499                 {
 500                         if (!IsAmbiguousTime (dateTimeOffset))
 501                                 throw new ArgumentException ("dateTimeOffset is not an ambiguous time");
 502
 503                         throw new NotImplementedException ();
 504                 }
 505
 506                 public override int GetHashCode ()
 507                 {
 508                         int hash_code = Id.GetHashCode ();
 509                         foreach (AdjustmentRule rule in GetAdjustmentRules ())
 510                                 hash_code ^= rule.GetHashCode ();
 511                         return hash_code;
 512                 }
 513
 514 #if NET_4_0
 515                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
 516 #else
 517                 public void GetObjectData (SerializationInfo info, StreamingContext context)
 518 #endif
 519                 {
 520                         throw new NotImplementedException ();
 521                 }
 522
 523                 //FIXME: change this to a generic Dictionary and allow caching for FindSystemTimeZoneById
 524                 private static List<TimeZoneInfo> systemTimeZones = null;
 525                 public static ReadOnlyCollection<TimeZoneInfo> GetSystemTimeZones ()
 526                 {
 527                         if (systemTimeZones == null) {
 528                                 systemTimeZones = new List<TimeZoneInfo> ();
 529 #if !NET_2_1
 530                                 if (TimeZoneKey != null) {
 531                                         foreach (string id in TimeZoneKey.GetSubKeyNames ()) {
 532                                                 try {
 533                                                         systemTimeZones.Add (FindSystemTimeZoneById (id));
 534                                                 } catch {}
 535                                         }
 536
 537                                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 538                                 }
 539 #endif
 540 #if MONODROID
 541                         foreach (string id in ZoneInfoDB.GetAvailableIds ()) {
 542                                 systemTimeZones.Add (ZoneInfoDB.GetTimeZone (id));
 543                         }
 544 #elif LIBC
 545                                 string[] continents = new string [] {"Africa", "America", "Antarctica", "Arctic", "Asia", "Atlantic", "Brazil", "Canada", "Chile", "Europe", "Indian", "Mexico", "Mideast", "Pacific", "US"};
 546                                 foreach (string continent in continents) {
 547                                         try {
 548                                                 foreach (string zonepath in Directory.GetFiles (Path.Combine (TimeZoneDirectory, continent))) {
 549                                                         try {
 550                                                                 string id = String.Format ("{0}/{1}", continent, Path.GetFileName (zonepath));
 551                                                                 systemTimeZones.Add (FindSystemTimeZoneById (id));
 552                                                         } catch (ArgumentNullException) {
 553                                                         } catch (TimeZoneNotFoundException) {
 554                                                         } catch (InvalidTimeZoneException) {
 555                                                         } catch (Exception) {
 556                                                                 throw;
 557                                                         }
 558                                                 }
 559                                         } catch {}
 560                                 }
 561 #else
 562                                 throw new NotImplementedException ("This method is not implemented for this platform");
 563 #endif
 564                         }
 565                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 566                 }
 567
 568                 public TimeSpan GetUtcOffset (DateTime dateTime)
 569                 {
 570                         if (IsDaylightSavingTime (dateTime)) {
 571                                 AdjustmentRule rule = GetApplicableRule (dateTime);
 572                                 if (rule != null)
 573                                         return BaseUtcOffset + rule.DaylightDelta;
 574                         }
 575
 576                         return BaseUtcOffset;
 577                 }
 578
 579                 public TimeSpan GetUtcOffset (DateTimeOffset dateTimeOffset)
 580                 {
 581                         throw new NotImplementedException ();
 582                 }
 583
 584                 public bool HasSameRules (TimeZoneInfo other)
 585                 {
 586                         if (other == null)
 587                                 throw new ArgumentNullException ("other");
 588
 589                         if ((this.adjustmentRules == null) != (other.adjustmentRules == null))
 590                                 return false;
 591
 592                         if (this.adjustmentRules == null)
 593                                 return true;
 594
 595                         if (this.BaseUtcOffset != other.BaseUtcOffset)
 596                                 return false;
 597
 598                         if (this.adjustmentRules.Length != other.adjustmentRules.Length)
 599                                 return false;
 600
 601                         for (int i = 0; i < adjustmentRules.Length; i++) {
 602                                 if (! (this.adjustmentRules [i]).Equals (other.adjustmentRules [i]))
 603                                         return false;
 604                         }
 605
 606                         return true;
 607                 }
 608
 609                 public bool IsAmbiguousTime (DateTime dateTime)
 610                 {
 611                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 612                                 throw new ArgumentException ("Kind is Local and time is Invalid");
 613
 614                         if (this == TimeZoneInfo.Utc)
 615                                 return false;
 616
 617                         if (dateTime.Kind == DateTimeKind.Utc)
 618                                 dateTime = ConvertTimeFromUtc (dateTime);
 619
 620                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 621                                 dateTime = ConvertTime (dateTime, TimeZoneInfo.Local, this);
 622
 623                         AdjustmentRule rule = GetApplicableRule (dateTime);
 624                         if (rule != null) {
 625                                 DateTime tpoint = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year);
 626                                 if (dateTime > tpoint - rule.DaylightDelta  && dateTime <= tpoint)
 627                                         return true;
 628                         }
 629
 630                         return false;
 631                 }
 632
 633                 public bool IsAmbiguousTime (DateTimeOffset dateTimeOffset)
 634                 {
 635                         throw new NotImplementedException ();
 636                 }
 637
 638                 public bool IsDaylightSavingTime (DateTime dateTime)
 639                 {
 640                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 641                                 throw new ArgumentException ("dateTime is invalid and Kind is Local");
 642
 643                         if (this == TimeZoneInfo.Utc)
 644                                 return false;
 645
 646                         if (!SupportsDaylightSavingTime)
 647                                 return false;
 648                         //FIXME: do not rely on DateTime implementation !
 649                         if ((dateTime.Kind == DateTimeKind.Local || dateTime.Kind == DateTimeKind.Unspecified) && this == TimeZoneInfo.Local)
 650                                 return dateTime.IsDaylightSavingTime ();
 651
 652                         //FIXME: do not rely on DateTime implementation !
 653                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Utc)
 654                                 return IsDaylightSavingTime (DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc));
 655
 656                         AdjustmentRule rule = GetApplicableRule (dateTime.Date);
 657                         if (rule == null)
 658                                 return false;
 659
 660                         DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 661                         DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
 662                         if (dateTime.Kind == DateTimeKind.Utc) {
 663                                 DST_start -= BaseUtcOffset;
 664                                 DST_end -= (BaseUtcOffset + rule.DaylightDelta);
 665                         }
 666
 667                         return (dateTime >= DST_start && dateTime < DST_end);
 668                 }
 669
 670                 public bool IsDaylightSavingTime (DateTimeOffset dateTimeOffset)
 671                 {
 672                         throw new NotImplementedException ();
 673                 }
 674
 675                 public bool IsInvalidTime (DateTime dateTime)
 676                 {
 677                         if (dateTime.Kind == DateTimeKind.Utc)
 678                                 return false;
 679                         if (dateTime.Kind == DateTimeKind.Local && this != Local)
 680                                 return false;
 681
 682                         AdjustmentRule rule = GetApplicableRule (dateTime);
 683                         if (rule != null) {
 684                                 DateTime tpoint = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 685                                 if (dateTime >= tpoint && dateTime < tpoint + rule.DaylightDelta)
 686                                         return true;
 687                         }
 688
 689                         return false;
 690                 }
 691
 692 #if NET_4_0
 693                 void IDeserializationCallback.OnDeserialization (object sender)
 694 #else
 695                 public void OnDeserialization (object sender)
 696 #endif
 697                 {
 698                         throw new NotImplementedException ();
 699                 }
 700
 701                 public string ToSerializedString ()
 702                 {
 703                         throw new NotImplementedException ();
 704                 }
 705
 706                 public override string ToString ()
 707                 {
 708                         return DisplayName;
 709                 }
 710
 711                 private TimeZoneInfo (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 712                 {
 713                         if (id == null)
 714                                 throw new ArgumentNullException ("id");
 715
 716                         if (id == String.Empty)
 717                                 throw new ArgumentException ("id parameter is an empty string");
 718
 719                         if (baseUtcOffset.Ticks % TimeSpan.TicksPerMinute != 0)
 720                                 throw new ArgumentException ("baseUtcOffset parameter does not represent a whole number of minutes");
 721
 722                         if (baseUtcOffset > new TimeSpan (14, 0, 0) || baseUtcOffset < new TimeSpan (-14, 0, 0))
 723                                 throw new ArgumentOutOfRangeException ("baseUtcOffset parameter is greater than 14 hours or less than -14 hours");
 724
 725 #if STRICT
 726                         if (id.Length > 32)
 727                                 throw new ArgumentException ("id parameter shouldn't be longer than 32 characters");
 728 #endif
 729
 730                         if (adjustmentRules != null && adjustmentRules.Length != 0) {
 731                                 AdjustmentRule prev = null;
 732                                 foreach (AdjustmentRule current in adjustmentRules) {
 733                                         if (current == null)
 734                                                 throw new InvalidTimeZoneException ("one or more elements in adjustmentRules are null");
 735
 736                                         if ((baseUtcOffset + current.DaylightDelta < new TimeSpan (-14, 0, 0)) ||
 737                                                         (baseUtcOffset + current.DaylightDelta > new TimeSpan (14, 0, 0)))
 738                                                 throw new InvalidTimeZoneException ("Sum of baseUtcOffset and DaylightDelta of one or more object in adjustmentRules array is greater than 14 or less than -14 hours;");
 739
 740                                         if (prev != null && prev.DateStart > current.DateStart)
 741                                                 throw new InvalidTimeZoneException ("adjustment rules specified in adjustmentRules parameter are not in chronological order");
 742
 743                                         if (prev != null && prev.DateEnd > current.DateStart)
 744                                                 throw new InvalidTimeZoneException ("some adjustment rules in the adjustmentRules parameter overlap");
 745
 746                                         if (prev != null && prev.DateEnd == current.DateStart)
 747                                                 throw new InvalidTimeZoneException ("a date can have multiple adjustment rules applied to it");
 748
 749                                         prev = current;
 750                                 }
 751                         }
 752
 753                         this.id = id;
 754                         this.baseUtcOffset = baseUtcOffset;
 755                         this.displayName = displayName ?? id;
 756                         this.standardDisplayName = standardDisplayName ?? id;
 757                         this.daylightDisplayName = daylightDisplayName;
 758                         this.disableDaylightSavingTime = disableDaylightSavingTime;
 759                         this.adjustmentRules = adjustmentRules;
 760                 }
 761
 762                 private AdjustmentRule GetApplicableRule (DateTime dateTime)
 763                 {
 764                         //Transitions are always in standard time
 765                         DateTime date = dateTime;
 766
 767                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 768                                 date = date.ToUniversalTime () + BaseUtcOffset;
 769
 770                         if (dateTime.Kind == DateTimeKind.Utc && this != TimeZoneInfo.Utc)
 771                                 date = date + BaseUtcOffset;
 772
 773                         if (adjustmentRules != null) {
 774                                 foreach (AdjustmentRule rule in adjustmentRules) {
 775                                         if (rule.DateStart > date.Date)
 776                                                 return null;
 777                                         if (rule.DateEnd < date.Date)
 778                                                 continue;
 779                                         return rule;
 780                                 }
 781                         }
 782                         return null;
 783                 }
 784
 785                 private static DateTime TransitionPoint (TransitionTime transition, int year)
 786                 {
 787                         if (transition.IsFixedDateRule)
 788                                 return new DateTime (year, transition.Month, transition.Day) + transition.TimeOfDay.TimeOfDay;
 789
 790                         DayOfWeek first = (new DateTime (year, transition.Month, 1)).DayOfWeek;
 791                         int day = 1 + (transition.Week - 1) * 7 + (transition.DayOfWeek - first) % 7;
 792                         if (day >  DateTime.DaysInMonth (year, transition.Month))
 793                                 day -= 7;
 794                         return new DateTime (year, transition.Month, day) + transition.TimeOfDay.TimeOfDay;
 795                 }
 796
 797                 static List<AdjustmentRule> ValidateRules (List<AdjustmentRule> adjustmentRules)
 798                 {
 799                         AdjustmentRule prev = null;
 800                         foreach (AdjustmentRule current in adjustmentRules.ToArray ()) {
 801                                 if (prev != null && prev.DateEnd > current.DateStart) {
 802                                         adjustmentRules.Remove (current);
 803                                 }
 804                                 prev = current;
 805                         }
 806                         return adjustmentRules;
 807                 }
 808
 809 #if LIBC || MONODROID
 810                 private static bool ValidTZFile (byte [] buffer, int length)
 811                 {
 812                         StringBuilder magic = new StringBuilder ();
 813
 814                         for (int i = 0; i < 4; i++)
 815                                 magic.Append ((char)buffer [i]);
 816
 817                         if (magic.ToString () != "TZif")
 818                                 return false;
 819
 820                         if (length >= BUFFER_SIZE)
 821                                 return false;
 822
 823                         return true;
 824                 }
 825
 826                 static int SwapInt32 (int i)
 827                 {
 828                         return (((i >> 24) & 0xff)
 829                                 | ((i >> 8) & 0xff00)
 830                                 | ((i << 8) & 0xff0000)
 831                                 | ((i << 24)));
 832                 }
 833
 834                 static int ReadBigEndianInt32 (byte [] buffer, int start)
 835                 {
 836                         int i = BitConverter.ToInt32 (buffer, start);
 837                         if (!BitConverter.IsLittleEndian)
 838                                 return i;
 839
 840                         return SwapInt32 (i);
 841                 }
 842
 843                 private static TimeZoneInfo ParseTZBuffer (string id, byte [] buffer, int length)
 844                 {
 845                         //Reading the header. 4 bytes for magic, 16 are reserved
 846                         int ttisgmtcnt = ReadBigEndianInt32 (buffer, 20);
 847                         int ttisstdcnt = ReadBigEndianInt32 (buffer, 24);
 848                         int leapcnt = ReadBigEndianInt32 (buffer, 28);
 849                         int timecnt = ReadBigEndianInt32 (buffer, 32);
 850                         int typecnt = ReadBigEndianInt32 (buffer, 36);
 851                         int charcnt = ReadBigEndianInt32 (buffer, 40);
 852
 853                         if (length < 44 + timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt)
 854                                 throw new InvalidTimeZoneException ();
 855
 856                         Dictionary<int, string> abbreviations = ParseAbbreviations (buffer, 44 + 4 * timecnt + timecnt + 6 * typecnt, charcnt);
 857                         Dictionary<int, TimeType> time_types = ParseTimesTypes (buffer, 44 + 4 * timecnt + timecnt, typecnt, abbreviations);
 858                         List<KeyValuePair<DateTime, TimeType>> transitions = ParseTransitions (buffer, 44, timecnt, time_types);
 859
 860                         if (time_types.Count == 0)
 861                                 throw new InvalidTimeZoneException ();
 862
 863                         if (time_types.Count == 1 && ((TimeType)time_types[0]).IsDst)
 864                                 throw new InvalidTimeZoneException ();
 865
 866                         TimeSpan baseUtcOffset = new TimeSpan (0);
 867                         TimeSpan dstDelta = new TimeSpan (0);
 868                         string standardDisplayName = null;
 869                         string daylightDisplayName = null;
 870                         bool dst_observed = false;
 871                         DateTime dst_start = DateTime.MinValue;
 872                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 873
 874                         for (int i = 0; i < transitions.Count; i++) {
 875                                 var pair = transitions [i];
 876                                 DateTime ttime = pair.Key;
 877                                 TimeType ttype = pair.Value;
 878                                 if (!ttype.IsDst) {
 879                                         if (standardDisplayName != ttype.Name || baseUtcOffset.TotalSeconds != ttype.Offset) {
 880                                                 standardDisplayName = ttype.Name;
 881                                                 daylightDisplayName = null;
 882                                                 baseUtcOffset = new TimeSpan (0, 0, ttype.Offset);
 883                                                 adjustmentRules = new List<AdjustmentRule> ();
 884                                                 dst_observed = false;
 885                                         }
 886                                         if (dst_observed) {
 887                                                 //FIXME: check additional fields for this:
 888                                                 //most of the transitions are expressed in GMT
 889                                                 dst_start += baseUtcOffset;
 890                                                 DateTime dst_end = ttime + baseUtcOffset + dstDelta;
 891
 892                                                 //some weird timezone (America/Phoenix) have end dates on Jan 1st
 893                                                 if (dst_end.Date == new DateTime (dst_end.Year, 1, 1) && dst_end.Year > dst_start.Year)
 894                                                         dst_end -= new TimeSpan (24, 0, 0);
 895
 896                                                 DateTime dateStart, dateEnd;
 897                                                 if (dst_start.Month < 7)
 898                                                         dateStart = new DateTime (dst_start.Year, 1, 1);
 899                                                 else
 900                                                         dateStart = new DateTime (dst_start.Year, 7, 1);
 901
 902                                                 if (dst_end.Month >= 7)
 903                                                         dateEnd = new DateTime (dst_end.Year, 12, 31);
 904                                                 else
 905                                                         dateEnd = new DateTime (dst_end.Year, 6, 30);
 906
 907
 908                                                 TransitionTime transition_start = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_start.TimeOfDay, dst_start.Month, dst_start.Day);
 909                                                 TransitionTime transition_end = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_end.TimeOfDay, dst_end.Month, dst_end.Day);
 910                                                 if  (transition_start != transition_end) //y, that happened in Argentina in 1943-1946
 911                                                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (dateStart, dateEnd, dstDelta, transition_start, transition_end));
 912                                         }
 913                                         dst_observed = false;
 914                                 } else {
 915                                         if (daylightDisplayName != ttype.Name || dstDelta.TotalSeconds != ttype.Offset - baseUtcOffset.TotalSeconds) {
 916                                                 daylightDisplayName = ttype.Name;
 917                                                 dstDelta = new TimeSpan(0, 0, ttype.Offset) - baseUtcOffset;
 918                                         }
 919                                         dst_start = ttime;
 920                                         dst_observed = true;
 921                                 }
 922                         }
 923
 924                         if (adjustmentRules.Count == 0) {
 925                                 TimeType t = (TimeType)time_types [0];
 926                                 if (standardDisplayName == null) {
 927                                         standardDisplayName = t.Name;
 928                                         baseUtcOffset = new TimeSpan (0, 0, t.Offset);
 929                                 }
 930                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName);
 931                         } else {
 932                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName, daylightDisplayName, ValidateRules (adjustmentRules).ToArray ());
 933                         }
 934                 }
 935
 936                 static Dictionary<int, string> ParseAbbreviations (byte [] buffer, int index, int count)
 937                 {
 938                         var abbrevs = new Dictionary<int, string> ();
 939                         int abbrev_index = 0;
 940                         var sb = new StringBuilder ();
 941                         for (int i = 0; i < count; i++) {
 942                                 char c = (char) buffer [index + i];
 943                                 if (c != '\0')
 944                                         sb.Append (c);
 945                                 else {
 946                                         abbrevs.Add (abbrev_index, sb.ToString ());
 947                                         //Adding all the substrings too, as it seems to be used, at least for Africa/Windhoek
 948                                         for (int j = 1; j < sb.Length; j++)
 949                                                 abbrevs.Add (abbrev_index + j, sb.ToString (j, sb.Length - j));
 950                                         abbrev_index = i + 1;
 951                                         sb = new StringBuilder ();
 952                                 }
 953                         }
 954                         return abbrevs;
 955                 }
 956
 957                 static Dictionary<int, TimeType> ParseTimesTypes (byte [] buffer, int index, int count, Dictionary<int, string> abbreviations)
 958                 {
 959                         var types = new Dictionary<int, TimeType> (count);
 960                         for (int i = 0; i < count; i++) {
 961                                 int offset = ReadBigEndianInt32 (buffer, index + 6 * i);
 962                                 byte is_dst = buffer [index + 6 * i + 4];
 963                                 byte abbrev = buffer [index + 6 * i + 5];
 964                                 types.Add (i, new TimeType (offset, (is_dst != 0), abbreviations [(int)abbrev]));
 965                         }
 966                         return types;
 967                 }
 968
 969                 static List<KeyValuePair<DateTime, TimeType>> ParseTransitions (byte [] buffer, int index, int count, Dictionary<int, TimeType> time_types)
 970                 {
 971                         var list = new List<KeyValuePair<DateTime, TimeType>> (count);
 972                         for (int i = 0; i < count; i++) {
 973                                 int unixtime = ReadBigEndianInt32 (buffer, index + 4 * i);
 974                                 DateTime ttime = DateTimeFromUnixTime (unixtime);
 975                                 byte ttype = buffer [index + 4 * count + i];
 976                                 list.Add (new KeyValuePair<DateTime, TimeType> (ttime, time_types [(int)ttype]));
 977                         }
 978                         return list;
 979                 }
 980
 981                 static DateTime DateTimeFromUnixTime (long unix_time)
 982                 {
 983                         DateTime date_time = new DateTime (1970, 1, 1);
 984                         return date_time.AddSeconds (unix_time);
 985                 }
 986         }
 987
 988         struct TimeType {
 989                 public readonly int Offset;
 990                 public readonly bool IsDst;
 991                 public string Name;
 992
 993                 public TimeType (int offset, bool is_dst, string abbrev)
 994                 {
 995                         this.Offset = offset;
 996                         this.IsDst = is_dst;
 997                         this.Name = abbrev;
 998                 }
 999
1000                 public override string ToString ()
1001                 {
1002                         return "offset: " + Offset + "s, is_dst: " + IsDst + ", zone name: " + Name;
1003                 }
1004 #else
1005         }
1006 #endif
1007         }
1008 }
1009
1010 #endif