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 MONOTOUCH
  91                                         using (Stream stream = GetMonoTouchDefault ()) {
  92                                                 return BuildFromStream ("Local", stream);
  93                                         }
  94 #elif LIBC
  95                                         try {
  96                                                 local = FindSystemTimeZoneByFileName ("Local", "/etc/localtime");
  97                                         } catch {
  98                                                 try {
  99                                                         local = FindSystemTimeZoneByFileName ("Local", Path.Combine (TimeZoneDirectory, "localtime"));
 100                                                 } catch {
 101                                                         throw new TimeZoneNotFoundException ();
 102                                                 }
 103                                         }
 104 #else
 105                                         if (IsWindows && LocalZoneKey != null) {
 106                                                 string name = (string)LocalZoneKey.GetValue ("TimeZoneKeyName");
 107                                                 name = TrimSpecial (name);
 108                                                 if (name != null)
 109                                                         local = TimeZoneInfo.FindSystemTimeZoneById (name);
 110                                         }
 111
 112                                         if (local == null)
 113                                                 throw new TimeZoneNotFoundException ();
 114 #endif
 115                                 }
 116                                 return local;
 117                         }
 118                 }
 119
 120                 string standardDisplayName;
 121                 public string StandardName {
 122                         get { return standardDisplayName; }
 123                 }
 124
 125                 bool disableDaylightSavingTime;
 126                 public bool SupportsDaylightSavingTime {
 127                         get  { return !disableDaylightSavingTime; }
 128                 }
 129
 130                 static TimeZoneInfo utc;
 131                 public static TimeZoneInfo Utc {
 132                         get {
 133                                 if (utc == null)
 134                                         utc = CreateCustomTimeZone ("UTC", new TimeSpan (0), "UTC", "UTC");
 135                                 return utc;
 136                         }
 137                 }
 138 #if LIBC
 139                 static string timeZoneDirectory = null;
 140                 static string TimeZoneDirectory {
 141                         get {
 142                                 if (timeZoneDirectory == null)
 143                                         timeZoneDirectory = "/usr/share/zoneinfo";
 144                                 return timeZoneDirectory;
 145                         }
 146                         set {
 147                                 ClearCachedData ();
 148                                 timeZoneDirectory = value;
 149                         }
 150                 }
 151 #endif
 152                 private AdjustmentRule [] adjustmentRules;
 153
 154 #if !NET_2_1
 155                 /// <summary>
 156                 /// Determine whether windows of not (taken Stephane Delcroix's code)
 157                 /// </summary>
 158                 private static bool IsWindows
 159                 {
 160                         get {
 161                                 int platform = (int) Environment.OSVersion.Platform;
 162                                 return ((platform != 4) && (platform != 6) && (platform != 128));
 163                         }
 164                 }
 165
 166                 /// <summary>
 167                 /// Needed to trim misc garbage in MS registry keys
 168                 /// </summary>
 169                 private static string TrimSpecial (string str)
 170                 {
 171                         var Istart = 0;
 172                         while (Istart < str.Length && !char.IsLetterOrDigit(str[Istart])) Istart++;
 173                         var Iend = str.Length - 1;
 174                         while (Iend > Istart && !char.IsLetterOrDigit(str[Iend])) Iend--;
 175
 176                         return str.Substring (Istart, Iend-Istart+1);
 177                 }
 178
 179                 static RegistryKey timeZoneKey = null;
 180                 static RegistryKey TimeZoneKey {
 181                         get {
 182                                 if (timeZoneKey != null)
 183                                         return timeZoneKey;
 184                                 if (!IsWindows)
 185                                         return null;
 186
 187                                 return timeZoneKey = Registry.LocalMachine.OpenSubKey (
 188                                         "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
 189                                         false);
 190                         }
 191                 }
 192
 193                 static RegistryKey localZoneKey = null;
 194                 static RegistryKey LocalZoneKey {
 195                         get {
 196                                 if (localZoneKey != null)
 197                                         return localZoneKey;
 198
 199                                 if (!IsWindows)
 200                                         return null;
 201
 202                                 return localZoneKey = Registry.LocalMachine.OpenSubKey (
 203                                         "SYSTEM\\CurrentControlSet\\Control\\TimeZoneInformation", false);
 204                         }
 205                 }
 206 #endif
 207
 208                 public static void ClearCachedData ()
 209                 {
 210                         local = null;
 211                         utc = null;
 212                         systemTimeZones = null;
 213                 }
 214
 215                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 216                 {
 217                         return ConvertTime (dateTime, TimeZoneInfo.Local, destinationTimeZone);
 218                 }
 219
 220                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)
 221                 {
 222                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 223                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 224
 225                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 226                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 227
 228                         if (sourceTimeZone.IsInvalidTime (dateTime))
 229                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 230
 231                         if (sourceTimeZone == null)
 232                                 throw new ArgumentNullException ("sourceTimeZone");
 233
 234                         if (destinationTimeZone == null)
 235                                 throw new ArgumentNullException ("destinationTimeZone");
 236
 237                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone == TimeZoneInfo.Local && destinationTimeZone == TimeZoneInfo.Local)
 238                                 return dateTime;
 239
 240                         DateTime utc = ConvertTimeToUtc (dateTime);
 241
 242                         if (destinationTimeZone == TimeZoneInfo.Utc)
 243                                 return utc;
 244
 245                         return ConvertTimeFromUtc (utc, destinationTimeZone);
 246
 247                 }
 248
 249                 public static DateTimeOffset ConvertTime (DateTimeOffset dateTimeOffset, TimeZoneInfo destinationTimeZone)
 250                 {
 251                         throw new NotImplementedException ();
 252                 }
 253
 254                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string destinationTimeZoneId)
 255                 {
 256                         return ConvertTime (dateTime, FindSystemTimeZoneById (destinationTimeZoneId));
 257                 }
 258
 259                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string sourceTimeZoneId, string destinationTimeZoneId)
 260                 {
 261                         return ConvertTime (dateTime, FindSystemTimeZoneById (sourceTimeZoneId), FindSystemTimeZoneById (destinationTimeZoneId));
 262                 }
 263
 264                 public static DateTimeOffset ConvertTimeBySystemTimeZoneId (DateTimeOffset dateTimeOffset, string destinationTimeZoneId)
 265                 {
 266                         return ConvertTime (dateTimeOffset, FindSystemTimeZoneById (destinationTimeZoneId));
 267                 }
 268
 269                 private DateTime ConvertTimeFromUtc (DateTime dateTime)
 270                 {
 271                         if (dateTime.Kind == DateTimeKind.Local)
 272                                 throw new ArgumentException ("Kind property of dateTime is Local");
 273
 274                         if (this == TimeZoneInfo.Utc)
 275                                 return DateTime.SpecifyKind (dateTime, DateTimeKind.Utc);
 276
 277                         //FIXME: do not rely on DateTime implementation !
 278                         if (this == TimeZoneInfo.Local)
 279                                 return DateTime.SpecifyKind (dateTime.ToLocalTime (), DateTimeKind.Unspecified);
 280
 281                         AdjustmentRule rule = GetApplicableRule (dateTime);
 282
 283                         if (rule != null && IsDaylightSavingTime (DateTime.SpecifyKind (dateTime, DateTimeKind.Utc)))
 284                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset + rule.DaylightDelta , DateTimeKind.Unspecified);
 285                         else
 286                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset, DateTimeKind.Unspecified);
 287                 }
 288
 289                 public static DateTime ConvertTimeFromUtc (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 290                 {
 291                         if (destinationTimeZone == null)
 292                                 throw new ArgumentNullException ("destinationTimeZone");
 293
 294                         return destinationTimeZone.ConvertTimeFromUtc (dateTime);
 295                 }
 296
 297                 public static DateTime ConvertTimeToUtc (DateTime dateTime)
 298                 {
 299                         if (dateTime.Kind == DateTimeKind.Utc)
 300                                 return dateTime;
 301
 302                         //FIXME: do not rely on DateTime implementation !
 303                         return DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc);
 304                 }
 305
 306                 public static DateTime ConvertTimeToUtc (DateTime dateTime, TimeZoneInfo sourceTimeZone)
 307                 {
 308                         if (sourceTimeZone == null)
 309                                 throw new ArgumentNullException ("sourceTimeZone");
 310
 311                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 312                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 313
 314                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 315                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 316
 317                         if (sourceTimeZone.IsInvalidTime (dateTime))
 318                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 319
 320                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone == TimeZoneInfo.Utc)
 321                                 return dateTime;
 322
 323                         if (dateTime.Kind == DateTimeKind.Utc)
 324                                 return dateTime;
 325
 326                         if (dateTime.Kind == DateTimeKind.Local)
 327                                 return ConvertTimeToUtc (dateTime);
 328
 329                         if (sourceTimeZone.IsAmbiguousTime (dateTime) || !sourceTimeZone.IsDaylightSavingTime (dateTime))
 330                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 331                         else {
 332                                 AdjustmentRule rule = sourceTimeZone.GetApplicableRule (dateTime);
 333                                 if (rule != null)
 334                                         return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset - rule.DaylightDelta, DateTimeKind.Utc);
 335                                 else
 336                                         return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 337                         }
 338                 }
 339
 340                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName)
 341                 {
 342                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, null, null, true);
 343                 }
 344
 345                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules)
 346                 {
 347                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, false);
 348                 }
 349
 350                 public static TimeZoneInfo CreateCustomTimeZone ( string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 351                 {
 352                         return new TimeZoneInfo (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, disableDaylightSavingTime);
 353                 }
 354
 355                 public bool Equals (TimeZoneInfo other)
 356                 {
 357                         if (other == null)
 358                                 return false;
 359
 360                         return other.Id == this.Id && HasSameRules (other);
 361                 }
 362
 363                 public static TimeZoneInfo FindSystemTimeZoneById (string id)
 364                 {
 365                         //FIXME: this method should check for cached values in systemTimeZones
 366                         if (id == null)
 367                                 throw new ArgumentNullException ("id");
 368 #if !NET_2_1
 369                         if (TimeZoneKey != null)
 370                         {
 371                                 RegistryKey key = TimeZoneKey.OpenSubKey (id, false);
 372                                 if (key == null)
 373                                         throw new TimeZoneNotFoundException ();
 374                                 return FromRegistryKey(id, key);
 375                         }
 376 #endif
 377 #if MONODROID
 378                         return ZoneInfoDB.GetTimeZone (id);
 379 #else
 380                         // Local requires special logic that already exists in the Local property (bug #326)
 381                         if (id == "Local")
 382                                 return Local;
 383 #if MONOTOUCH
 384                         using (Stream stream = GetMonoTouchData (id)) {
 385                                 return BuildFromStream (id, stream);
 386                         }
 387 #elif LIBC
 388                         string filepath = Path.Combine (TimeZoneDirectory, id);
 389                         return FindSystemTimeZoneByFileName (id, filepath);
 390 #else
 391                         throw new NotImplementedException ();
 392 #endif
 393 #endif
 394                 }
 395
 396 #if LIBC
 397                 private static TimeZoneInfo FindSystemTimeZoneByFileName (string id, string filepath)
 398                 {
 399                         if (!File.Exists (filepath))
 400                                 throw new TimeZoneNotFoundException ();
 401
 402                         using (FileStream stream = File.OpenRead (filepath)) {
 403                                 return BuildFromStream (id, stream);
 404                         }
 405                 }
 406 #endif
 407 #if LIBC || MONOTOUCH
 408                 const int BUFFER_SIZE = 16384; //Big enough for any tz file (on Oct 2008, all tz files are under 10k)
 409
 410                 private static TimeZoneInfo BuildFromStream (string id, Stream stream)
 411                 {
 412                         byte [] buffer = new byte [BUFFER_SIZE];
 413                         int length = stream.Read (buffer, 0, BUFFER_SIZE);
 414
 415                         if (!ValidTZFile (buffer, length))
 416                                 throw new InvalidTimeZoneException ("TZ file too big for the buffer");
 417
 418                         try {
 419                                 return ParseTZBuffer (id, buffer, length);
 420                         } catch (Exception e) {
 421                                 throw new InvalidTimeZoneException (e.Message);
 422                         }
 423                 }
 424 #endif
 425
 426 #if !NET_2_1
 427                 private static TimeZoneInfo FromRegistryKey (string id, RegistryKey key)
 428                 {
 429                         byte [] reg_tzi = (byte []) key.GetValue ("TZI");
 430
 431                         if (reg_tzi == null)
 432                                 throw new InvalidTimeZoneException ();
 433
 434                         int bias = BitConverter.ToInt32 (reg_tzi, 0);
 435                         TimeSpan baseUtcOffset = new TimeSpan (0, -bias, 0);
 436
 437                         string display_name = (string) key.GetValue ("Display");
 438                         string standard_name = (string) key.GetValue ("Std");
 439                         string daylight_name = (string) key.GetValue ("Dlt");
 440
 441                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 442
 443                         RegistryKey dst_key = key.OpenSubKey ("Dynamic DST", false);
 444                         if (dst_key != null) {
 445                                 int first_year = (int) dst_key.GetValue ("FirstEntry");
 446                                 int last_year = (int) dst_key.GetValue ("LastEntry");
 447                                 int year;
 448
 449                                 for (year=first_year; year<=last_year; year++) {
 450                                         byte [] dst_tzi = (byte []) dst_key.GetValue (year.ToString ());
 451                                         if (dst_tzi != null) {
 452                                                 int start_year = year == first_year ? 1 : year;
 453                                                 int end_year = year == last_year ? 9999 : year;
 454                                                 ParseRegTzi(adjustmentRules, start_year, end_year, dst_tzi);
 455                                         }
 456                                 }
 457                         }
 458                         else
 459                                 ParseRegTzi(adjustmentRules, 1, 9999, reg_tzi);
 460
 461                         return CreateCustomTimeZone (id, baseUtcOffset, display_name, standard_name, daylight_name, ValidateRules (adjustmentRules).ToArray ());
 462                 }
 463
 464                 private static void ParseRegTzi (List<AdjustmentRule> adjustmentRules, int start_year, int end_year, byte [] buffer)
 465                 {
 466                         //int standard_bias = BitConverter.ToInt32 (buffer, 4); /* not sure how to handle this */
 467                         int daylight_bias = BitConverter.ToInt32 (buffer, 8);
 468
 469                         int standard_year = BitConverter.ToInt16 (buffer, 12);
 470                         int standard_month = BitConverter.ToInt16 (buffer, 14);
 471                         int standard_dayofweek = BitConverter.ToInt16 (buffer, 16);
 472                         int standard_day = BitConverter.ToInt16 (buffer, 18);
 473                         int standard_hour = BitConverter.ToInt16 (buffer, 20);
 474                         int standard_minute = BitConverter.ToInt16 (buffer, 22);
 475                         int standard_second = BitConverter.ToInt16 (buffer, 24);
 476                         int standard_millisecond = BitConverter.ToInt16 (buffer, 26);
 477
 478                         int daylight_year = BitConverter.ToInt16 (buffer, 28);
 479                         int daylight_month = BitConverter.ToInt16 (buffer, 30);
 480                         int daylight_dayofweek = BitConverter.ToInt16 (buffer, 32);
 481                         int daylight_day = BitConverter.ToInt16 (buffer, 34);
 482                         int daylight_hour = BitConverter.ToInt16 (buffer, 36);
 483                         int daylight_minute = BitConverter.ToInt16 (buffer, 38);
 484                         int daylight_second = BitConverter.ToInt16 (buffer, 40);
 485                         int daylight_millisecond = BitConverter.ToInt16 (buffer, 42);
 486
 487                         if (standard_month == 0 || daylight_month == 0)
 488                                 return;
 489
 490                         DateTime start_date;
 491                         DateTime start_timeofday = new DateTime (1, 1, 1, daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 492                         TransitionTime start_transition_time;
 493
 494                         if (daylight_year == 0) {
 495                                 start_date = new DateTime (start_year, 1, 1);
 496                                 start_transition_time = TransitionTime.CreateFloatingDateRule (
 497                                         start_timeofday, daylight_month, daylight_day,
 498                                         (DayOfWeek) daylight_dayofweek);
 499                         }
 500                         else {
 501                                 start_date = new DateTime (daylight_year, daylight_month, daylight_day,
 502                                         daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 503                                 start_transition_time = TransitionTime.CreateFixedDateRule (
 504                                         start_timeofday, daylight_month, daylight_day);
 505                         }
 506
 507                         DateTime end_date;
 508                         DateTime end_timeofday = new DateTime (1, 1, 1, standard_hour, standard_minute, standard_second, standard_millisecond);
 509                         TransitionTime end_transition_time;
 510
 511                         if (standard_year == 0) {
 512                                 end_date = new DateTime (end_year, 12, 31);
 513                                 end_transition_time = TransitionTime.CreateFloatingDateRule (
 514                                         end_timeofday, standard_month, standard_day,
 515                                         (DayOfWeek) standard_dayofweek);
 516                         }
 517                         else {
 518                                 end_date = new DateTime (standard_year, standard_month, standard_day,
 519                                         standard_hour, standard_minute, standard_second, standard_millisecond);
 520                                 end_transition_time = TransitionTime.CreateFixedDateRule (
 521                                         end_timeofday, standard_month, standard_day);
 522                         }
 523
 524                         TimeSpan daylight_delta = new TimeSpan(0, -daylight_bias, 0);
 525
 526                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (
 527                                 start_date, end_date, daylight_delta,
 528                                 start_transition_time, end_transition_time));
 529                 }
 530 #endif
 531
 532                 public static TimeZoneInfo FromSerializedString (string source)
 533                 {
 534                         throw new NotImplementedException ();
 535                 }
 536
 537                 public AdjustmentRule [] GetAdjustmentRules ()
 538                 {
 539                         if (disableDaylightSavingTime)
 540                                 return new AdjustmentRule [0];
 541                         else
 542                                 return (AdjustmentRule []) adjustmentRules.Clone ();
 543                 }
 544
 545                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTime dateTime)
 546                 {
 547                         if (!IsAmbiguousTime (dateTime))
 548                                 throw new ArgumentException ("dateTime is not an ambiguous time");
 549
 550                         AdjustmentRule rule = GetApplicableRule (dateTime);
 551                         if (rule != null)
 552                                 return new TimeSpan[] {baseUtcOffset, baseUtcOffset + rule.DaylightDelta};
 553                         else
 554                                 return new TimeSpan[] {baseUtcOffset, baseUtcOffset};
 555                 }
 556
 557                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTimeOffset dateTimeOffset)
 558                 {
 559                         if (!IsAmbiguousTime (dateTimeOffset))
 560                                 throw new ArgumentException ("dateTimeOffset is not an ambiguous time");
 561
 562                         throw new NotImplementedException ();
 563                 }
 564
 565                 public override int GetHashCode ()
 566                 {
 567                         int hash_code = Id.GetHashCode ();
 568                         foreach (AdjustmentRule rule in GetAdjustmentRules ())
 569                                 hash_code ^= rule.GetHashCode ();
 570                         return hash_code;
 571                 }
 572
 573 #if NET_4_0
 574                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
 575 #else
 576                 public void GetObjectData (SerializationInfo info, StreamingContext context)
 577 #endif
 578                 {
 579                         throw new NotImplementedException ();
 580                 }
 581
 582                 //FIXME: change this to a generic Dictionary and allow caching for FindSystemTimeZoneById
 583                 private static List<TimeZoneInfo> systemTimeZones = null;
 584                 public static ReadOnlyCollection<TimeZoneInfo> GetSystemTimeZones ()
 585                 {
 586                         if (systemTimeZones == null) {
 587                                 systemTimeZones = new List<TimeZoneInfo> ();
 588 #if !NET_2_1
 589                                 if (TimeZoneKey != null) {
 590                                         foreach (string id in TimeZoneKey.GetSubKeyNames ()) {
 591                                                 try {
 592                                                         systemTimeZones.Add (FindSystemTimeZoneById (id));
 593                                                 } catch {}
 594                                         }
 595
 596                                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 597                                 }
 598 #endif
 599 #if MONODROID
 600                         foreach (string id in ZoneInfoDB.GetAvailableIds ()) {
 601                                 systemTimeZones.Add (ZoneInfoDB.GetTimeZone (id));
 602                         }
 603 #elif MONOTOUCH
 604                                 if (systemTimeZones.Count == 0) {
 605                                         foreach (string name in GetMonoTouchNames ()) {
 606                                                 using (Stream stream = GetMonoTouchData (name)) {
 607                                                         systemTimeZones.Add (BuildFromStream (name, stream));
 608                                                 }
 609                                         }
 610                                 }
 611 #elif LIBC
 612                                 string[] continents = new string [] {"Africa", "America", "Antarctica", "Arctic", "Asia", "Atlantic", "Brazil", "Canada", "Chile", "Europe", "Indian", "Mexico", "Mideast", "Pacific", "US"};
 613                                 foreach (string continent in continents) {
 614                                         try {
 615                                                 foreach (string zonepath in Directory.GetFiles (Path.Combine (TimeZoneDirectory, continent))) {
 616                                                         try {
 617                                                                 string id = String.Format ("{0}/{1}", continent, Path.GetFileName (zonepath));
 618                                                                 systemTimeZones.Add (FindSystemTimeZoneById (id));
 619                                                         } catch (ArgumentNullException) {
 620                                                         } catch (TimeZoneNotFoundException) {
 621                                                         } catch (InvalidTimeZoneException) {
 622                                                         } catch (Exception) {
 623                                                                 throw;
 624                                                         }
 625                                                 }
 626                                         } catch {}
 627                                 }
 628 #else
 629                                 throw new NotImplementedException ("This method is not implemented for this platform");
 630 #endif
 631                         }
 632                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 633                 }
 634
 635                 public TimeSpan GetUtcOffset (DateTime dateTime)
 636                 {
 637                         if (IsDaylightSavingTime (dateTime)) {
 638                                 AdjustmentRule rule = GetApplicableRule (dateTime);
 639                                 if (rule != null)
 640                                         return BaseUtcOffset + rule.DaylightDelta;
 641                         }
 642
 643                         return BaseUtcOffset;
 644                 }
 645
 646                 public TimeSpan GetUtcOffset (DateTimeOffset dateTimeOffset)
 647                 {
 648                         throw new NotImplementedException ();
 649                 }
 650
 651                 public bool HasSameRules (TimeZoneInfo other)
 652                 {
 653                         if (other == null)
 654                                 throw new ArgumentNullException ("other");
 655
 656                         if ((this.adjustmentRules == null) != (other.adjustmentRules == null))
 657                                 return false;
 658
 659                         if (this.adjustmentRules == null)
 660                                 return true;
 661
 662                         if (this.BaseUtcOffset != other.BaseUtcOffset)
 663                                 return false;
 664
 665                         if (this.adjustmentRules.Length != other.adjustmentRules.Length)
 666                                 return false;
 667
 668                         for (int i = 0; i < adjustmentRules.Length; i++) {
 669                                 if (! (this.adjustmentRules [i]).Equals (other.adjustmentRules [i]))
 670                                         return false;
 671                         }
 672
 673                         return true;
 674                 }
 675
 676                 public bool IsAmbiguousTime (DateTime dateTime)
 677                 {
 678                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 679                                 throw new ArgumentException ("Kind is Local and time is Invalid");
 680
 681                         if (this == TimeZoneInfo.Utc)
 682                                 return false;
 683
 684                         if (dateTime.Kind == DateTimeKind.Utc)
 685                                 dateTime = ConvertTimeFromUtc (dateTime);
 686
 687                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 688                                 dateTime = ConvertTime (dateTime, TimeZoneInfo.Local, this);
 689
 690                         AdjustmentRule rule = GetApplicableRule (dateTime);
 691                         if (rule != null) {
 692                                 DateTime tpoint = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year);
 693                                 if (dateTime > tpoint - rule.DaylightDelta  && dateTime <= tpoint)
 694                                         return true;
 695                         }
 696
 697                         return false;
 698                 }
 699
 700                 public bool IsAmbiguousTime (DateTimeOffset dateTimeOffset)
 701                 {
 702                         throw new NotImplementedException ();
 703                 }
 704
 705                 public bool IsDaylightSavingTime (DateTime dateTime)
 706                 {
 707                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 708                                 throw new ArgumentException ("dateTime is invalid and Kind is Local");
 709
 710                         if (this == TimeZoneInfo.Utc)
 711                                 return false;
 712
 713                         if (!SupportsDaylightSavingTime)
 714                                 return false;
 715                         //FIXME: do not rely on DateTime implementation !
 716                         if ((dateTime.Kind == DateTimeKind.Local || dateTime.Kind == DateTimeKind.Unspecified) && this == TimeZoneInfo.Local)
 717                                 return dateTime.IsDaylightSavingTime ();
 718
 719                         //FIXME: do not rely on DateTime implementation !
 720                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Utc)
 721                                 return IsDaylightSavingTime (DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc));
 722
 723                         AdjustmentRule rule = GetApplicableRule (dateTime.Date);
 724                         if (rule == null)
 725                                 return false;
 726
 727                         DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 728                         DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
 729                         if (dateTime.Kind == DateTimeKind.Utc) {
 730                                 DST_start -= BaseUtcOffset;
 731                                 DST_end -= (BaseUtcOffset + rule.DaylightDelta);
 732                         }
 733
 734                         return (dateTime >= DST_start && dateTime < DST_end);
 735                 }
 736
 737                 public bool IsDaylightSavingTime (DateTimeOffset dateTimeOffset)
 738                 {
 739                         throw new NotImplementedException ();
 740                 }
 741
 742                 public bool IsInvalidTime (DateTime dateTime)
 743                 {
 744                         if (dateTime.Kind == DateTimeKind.Utc)
 745                                 return false;
 746                         if (dateTime.Kind == DateTimeKind.Local && this != Local)
 747                                 return false;
 748
 749                         AdjustmentRule rule = GetApplicableRule (dateTime);
 750                         if (rule != null) {
 751                                 DateTime tpoint = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 752                                 if (dateTime >= tpoint && dateTime < tpoint + rule.DaylightDelta)
 753                                         return true;
 754                         }
 755
 756                         return false;
 757                 }
 758
 759 #if NET_4_0
 760                 void IDeserializationCallback.OnDeserialization (object sender)
 761 #else
 762                 public void OnDeserialization (object sender)
 763 #endif
 764                 {
 765                         throw new NotImplementedException ();
 766                 }
 767
 768                 public string ToSerializedString ()
 769                 {
 770                         throw new NotImplementedException ();
 771                 }
 772
 773                 public override string ToString ()
 774                 {
 775                         return DisplayName;
 776                 }
 777
 778                 private TimeZoneInfo (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 779                 {
 780                         if (id == null)
 781                                 throw new ArgumentNullException ("id");
 782
 783                         if (id == String.Empty)
 784                                 throw new ArgumentException ("id parameter is an empty string");
 785
 786                         if (baseUtcOffset.Ticks % TimeSpan.TicksPerMinute != 0)
 787                                 throw new ArgumentException ("baseUtcOffset parameter does not represent a whole number of minutes");
 788
 789                         if (baseUtcOffset > new TimeSpan (14, 0, 0) || baseUtcOffset < new TimeSpan (-14, 0, 0))
 790                                 throw new ArgumentOutOfRangeException ("baseUtcOffset parameter is greater than 14 hours or less than -14 hours");
 791
 792 #if STRICT
 793                         if (id.Length > 32)
 794                                 throw new ArgumentException ("id parameter shouldn't be longer than 32 characters");
 795 #endif
 796
 797                         if (adjustmentRules != null && adjustmentRules.Length != 0) {
 798                                 AdjustmentRule prev = null;
 799                                 foreach (AdjustmentRule current in adjustmentRules) {
 800                                         if (current == null)
 801                                                 throw new InvalidTimeZoneException ("one or more elements in adjustmentRules are null");
 802
 803                                         if ((baseUtcOffset + current.DaylightDelta < new TimeSpan (-14, 0, 0)) ||
 804                                                         (baseUtcOffset + current.DaylightDelta > new TimeSpan (14, 0, 0)))
 805                                                 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;");
 806
 807                                         if (prev != null && prev.DateStart > current.DateStart)
 808                                                 throw new InvalidTimeZoneException ("adjustment rules specified in adjustmentRules parameter are not in chronological order");
 809
 810                                         if (prev != null && prev.DateEnd > current.DateStart)
 811                                                 throw new InvalidTimeZoneException ("some adjustment rules in the adjustmentRules parameter overlap");
 812
 813                                         if (prev != null && prev.DateEnd == current.DateStart)
 814                                                 throw new InvalidTimeZoneException ("a date can have multiple adjustment rules applied to it");
 815
 816                                         prev = current;
 817                                 }
 818                         }
 819
 820                         this.id = id;
 821                         this.baseUtcOffset = baseUtcOffset;
 822                         this.displayName = displayName ?? id;
 823                         this.standardDisplayName = standardDisplayName ?? id;
 824                         this.daylightDisplayName = daylightDisplayName;
 825                         this.disableDaylightSavingTime = disableDaylightSavingTime;
 826                         this.adjustmentRules = adjustmentRules;
 827                 }
 828
 829                 private AdjustmentRule GetApplicableRule (DateTime dateTime)
 830                 {
 831                         //Transitions are always in standard time
 832                         DateTime date = dateTime;
 833
 834                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 835                                 date = date.ToUniversalTime () + BaseUtcOffset;
 836
 837                         if (dateTime.Kind == DateTimeKind.Utc && this != TimeZoneInfo.Utc)
 838                                 date = date + BaseUtcOffset;
 839
 840                         if (adjustmentRules != null) {
 841                                 foreach (AdjustmentRule rule in adjustmentRules) {
 842                                         if (rule.DateStart > date.Date)
 843                                                 return null;
 844                                         if (rule.DateEnd < date.Date)
 845                                                 continue;
 846                                         return rule;
 847                                 }
 848                         }
 849                         return null;
 850                 }
 851
 852                 private static DateTime TransitionPoint (TransitionTime transition, int year)
 853                 {
 854                         if (transition.IsFixedDateRule)
 855                                 return new DateTime (year, transition.Month, transition.Day) + transition.TimeOfDay.TimeOfDay;
 856
 857                         DayOfWeek first = (new DateTime (year, transition.Month, 1)).DayOfWeek;
 858                         int day = 1 + (transition.Week - 1) * 7 + (transition.DayOfWeek - first) % 7;
 859                         if (day >  DateTime.DaysInMonth (year, transition.Month))
 860                                 day -= 7;
 861                         return new DateTime (year, transition.Month, day) + transition.TimeOfDay.TimeOfDay;
 862                 }
 863
 864                 static List<AdjustmentRule> ValidateRules (List<AdjustmentRule> adjustmentRules)
 865                 {
 866                         AdjustmentRule prev = null;
 867                         foreach (AdjustmentRule current in adjustmentRules.ToArray ()) {
 868                                 if (prev != null && prev.DateEnd > current.DateStart) {
 869                                         adjustmentRules.Remove (current);
 870                                 }
 871                                 prev = current;
 872                         }
 873                         return adjustmentRules;
 874                 }
 875
 876 #if LIBC || MONODROID
 877                 private static bool ValidTZFile (byte [] buffer, int length)
 878                 {
 879                         StringBuilder magic = new StringBuilder ();
 880
 881                         for (int i = 0; i < 4; i++)
 882                                 magic.Append ((char)buffer [i]);
 883
 884                         if (magic.ToString () != "TZif")
 885                                 return false;
 886
 887                         if (length >= BUFFER_SIZE)
 888                                 return false;
 889
 890                         return true;
 891                 }
 892
 893                 static int SwapInt32 (int i)
 894                 {
 895                         return (((i >> 24) & 0xff)
 896                                 | ((i >> 8) & 0xff00)
 897                                 | ((i << 8) & 0xff0000)
 898                                 | ((i << 24)));
 899                 }
 900
 901                 static int ReadBigEndianInt32 (byte [] buffer, int start)
 902                 {
 903                         int i = BitConverter.ToInt32 (buffer, start);
 904                         if (!BitConverter.IsLittleEndian)
 905                                 return i;
 906
 907                         return SwapInt32 (i);
 908                 }
 909
 910                 private static TimeZoneInfo ParseTZBuffer (string id, byte [] buffer, int length)
 911                 {
 912                         //Reading the header. 4 bytes for magic, 16 are reserved
 913                         int ttisgmtcnt = ReadBigEndianInt32 (buffer, 20);
 914                         int ttisstdcnt = ReadBigEndianInt32 (buffer, 24);
 915                         int leapcnt = ReadBigEndianInt32 (buffer, 28);
 916                         int timecnt = ReadBigEndianInt32 (buffer, 32);
 917                         int typecnt = ReadBigEndianInt32 (buffer, 36);
 918                         int charcnt = ReadBigEndianInt32 (buffer, 40);
 919
 920                         if (length < 44 + timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt)
 921                                 throw new InvalidTimeZoneException ();
 922
 923                         Dictionary<int, string> abbreviations = ParseAbbreviations (buffer, 44 + 4 * timecnt + timecnt + 6 * typecnt, charcnt);
 924                         Dictionary<int, TimeType> time_types = ParseTimesTypes (buffer, 44 + 4 * timecnt + timecnt, typecnt, abbreviations);
 925                         List<KeyValuePair<DateTime, TimeType>> transitions = ParseTransitions (buffer, 44, timecnt, time_types);
 926
 927                         if (time_types.Count == 0)
 928                                 throw new InvalidTimeZoneException ();
 929
 930                         if (time_types.Count == 1 && ((TimeType)time_types[0]).IsDst)
 931                                 throw new InvalidTimeZoneException ();
 932
 933                         TimeSpan baseUtcOffset = new TimeSpan (0);
 934                         TimeSpan dstDelta = new TimeSpan (0);
 935                         string standardDisplayName = null;
 936                         string daylightDisplayName = null;
 937                         bool dst_observed = false;
 938                         DateTime dst_start = DateTime.MinValue;
 939                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 940
 941                         for (int i = 0; i < transitions.Count; i++) {
 942                                 var pair = transitions [i];
 943                                 DateTime ttime = pair.Key;
 944                                 TimeType ttype = pair.Value;
 945                                 if (!ttype.IsDst) {
 946                                         if (standardDisplayName != ttype.Name || baseUtcOffset.TotalSeconds != ttype.Offset) {
 947                                                 standardDisplayName = ttype.Name;
 948                                                 daylightDisplayName = null;
 949                                                 baseUtcOffset = new TimeSpan (0, 0, ttype.Offset);
 950                                                 adjustmentRules = new List<AdjustmentRule> ();
 951                                                 dst_observed = false;
 952                                         }
 953                                         if (dst_observed) {
 954                                                 //FIXME: check additional fields for this:
 955                                                 //most of the transitions are expressed in GMT
 956                                                 dst_start += baseUtcOffset;
 957                                                 DateTime dst_end = ttime + baseUtcOffset + dstDelta;
 958
 959                                                 //some weird timezone (America/Phoenix) have end dates on Jan 1st
 960                                                 if (dst_end.Date == new DateTime (dst_end.Year, 1, 1) && dst_end.Year > dst_start.Year)
 961                                                         dst_end -= new TimeSpan (24, 0, 0);
 962
 963                                                 DateTime dateStart, dateEnd;
 964                                                 if (dst_start.Month < 7)
 965                                                         dateStart = new DateTime (dst_start.Year, 1, 1);
 966                                                 else
 967                                                         dateStart = new DateTime (dst_start.Year, 7, 1);
 968
 969                                                 if (dst_end.Month >= 7)
 970                                                         dateEnd = new DateTime (dst_end.Year, 12, 31);
 971                                                 else
 972                                                         dateEnd = new DateTime (dst_end.Year, 6, 30);
 973
 974
 975                                                 TransitionTime transition_start = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_start.TimeOfDay, dst_start.Month, dst_start.Day);
 976                                                 TransitionTime transition_end = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_end.TimeOfDay, dst_end.Month, dst_end.Day);
 977                                                 if  (transition_start != transition_end) //y, that happened in Argentina in 1943-1946
 978                                                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (dateStart, dateEnd, dstDelta, transition_start, transition_end));
 979                                         }
 980                                         dst_observed = false;
 981                                 } else {
 982                                         if (daylightDisplayName != ttype.Name || dstDelta.TotalSeconds != ttype.Offset - baseUtcOffset.TotalSeconds) {
 983                                                 daylightDisplayName = ttype.Name;
 984                                                 dstDelta = new TimeSpan(0, 0, ttype.Offset) - baseUtcOffset;
 985                                         }
 986                                         dst_start = ttime;
 987                                         dst_observed = true;
 988                                 }
 989                         }
 990
 991                         if (adjustmentRules.Count == 0) {
 992                                 TimeType t = (TimeType)time_types [0];
 993                                 if (standardDisplayName == null) {
 994                                         standardDisplayName = t.Name;
 995                                         baseUtcOffset = new TimeSpan (0, 0, t.Offset);
 996                                 }
 997                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName);
 998                         } else {
 999                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName, daylightDisplayName, ValidateRules (adjustmentRules).ToArray ());
1000                         }
1001                 }
1002
1003                 static Dictionary<int, string> ParseAbbreviations (byte [] buffer, int index, int count)
1004                 {
1005                         var abbrevs = new Dictionary<int, string> ();
1006                         int abbrev_index = 0;
1007                         var sb = new StringBuilder ();
1008                         for (int i = 0; i < count; i++) {
1009                                 char c = (char) buffer [index + i];
1010                                 if (c != '\0')
1011                                         sb.Append (c);
1012                                 else {
1013                                         abbrevs.Add (abbrev_index, sb.ToString ());
1014                                         //Adding all the substrings too, as it seems to be used, at least for Africa/Windhoek
1015                                         for (int j = 1; j < sb.Length; j++)
1016                                                 abbrevs.Add (abbrev_index + j, sb.ToString (j, sb.Length - j));
1017                                         abbrev_index = i + 1;
1018                                         sb = new StringBuilder ();
1019                                 }
1020                         }
1021                         return abbrevs;
1022                 }
1023
1024                 static Dictionary<int, TimeType> ParseTimesTypes (byte [] buffer, int index, int count, Dictionary<int, string> abbreviations)
1025                 {
1026                         var types = new Dictionary<int, TimeType> (count);
1027                         for (int i = 0; i < count; i++) {
1028                                 int offset = ReadBigEndianInt32 (buffer, index + 6 * i);
1029                                 byte is_dst = buffer [index + 6 * i + 4];
1030                                 byte abbrev = buffer [index + 6 * i + 5];
1031                                 types.Add (i, new TimeType (offset, (is_dst != 0), abbreviations [(int)abbrev]));
1032                         }
1033                         return types;
1034                 }
1035
1036                 static List<KeyValuePair<DateTime, TimeType>> ParseTransitions (byte [] buffer, int index, int count, Dictionary<int, TimeType> time_types)
1037                 {
1038                         var list = new List<KeyValuePair<DateTime, TimeType>> (count);
1039                         for (int i = 0; i < count; i++) {
1040                                 int unixtime = ReadBigEndianInt32 (buffer, index + 4 * i);
1041                                 DateTime ttime = DateTimeFromUnixTime (unixtime);
1042                                 byte ttype = buffer [index + 4 * count + i];
1043                                 list.Add (new KeyValuePair<DateTime, TimeType> (ttime, time_types [(int)ttype]));
1044                         }
1045                         return list;
1046                 }
1047
1048                 static DateTime DateTimeFromUnixTime (long unix_time)
1049                 {
1050                         DateTime date_time = new DateTime (1970, 1, 1);
1051                         return date_time.AddSeconds (unix_time);
1052                 }
1053         }
1054
1055         struct TimeType {
1056                 public readonly int Offset;
1057                 public readonly bool IsDst;
1058                 public string Name;
1059
1060                 public TimeType (int offset, bool is_dst, string abbrev)
1061                 {
1062                         this.Offset = offset;
1063                         this.IsDst = is_dst;
1064                         this.Name = abbrev;
1065                 }
1066
1067                 public override string ToString ()
1068                 {
1069                         return "offset: " + Offset + "s, is_dst: " + IsDst + ", zone name: " + Name;
1070                 }
1071 #else
1072         }
1073 #endif
1074         }
1075 }
1076
1077 #endif