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

   1 /*
   2  * System.TimeZoneInfo
   3  *
   4  * Author(s)
   5  *      Stephane Delcroix <stephane@delcroix.org>
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining
   8  * a copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sublicense, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be
  16  * included in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  22  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  23  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  24  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27 using System;
  28 using System.Runtime.CompilerServices;
  29
  30 #if !INSIDE_CORLIB && (NET_4_0 || BOOTSTRAP_NET_4_0 || MOONLIGHT)
  31
  32 [assembly:TypeForwardedTo (typeof(TimeZoneInfo))]
  33
  34 #elif NET_3_5 || (MOBILE && !INSIDE_CORLIB) || (MOONLIGHT && INSIDE_CORLIB)
  35
  36 using System.Collections.Generic;
  37 using System.Collections.ObjectModel;
  38 using System.Linq;
  39 using System.Runtime.Serialization;
  40 using System.Text;
  41
  42 #if LIBC || MONODROID
  43 using System.IO;
  44 using Mono;
  45 #endif
  46
  47 using Microsoft.Win32;
  48
  49 namespace System
  50 {
  51 #if NET_4_0 || BOOTSTRAP_NET_4_0
  52         [TypeForwardedFrom (Consts.AssemblySystemCore_3_5)]
  53 #elif MOONLIGHT
  54         [TypeForwardedFrom (Consts.AssemblySystem_Core)]
  55 #endif
  56         [SerializableAttribute]
  57         public sealed partial class TimeZoneInfo : IEquatable<TimeZoneInfo>, ISerializable, IDeserializationCallback
  58         {
  59                 TimeSpan baseUtcOffset;
  60                 public TimeSpan BaseUtcOffset {
  61                         get { return baseUtcOffset; }
  62                 }
  63
  64                 string daylightDisplayName;
  65                 public string DaylightName {
  66                         get {
  67                                 if (disableDaylightSavingTime)
  68                                         return String.Empty;
  69                                 return daylightDisplayName;
  70                         }
  71                 }
  72
  73                 string displayName;
  74                 public string DisplayName {
  75                         get { return displayName; }
  76                 }
  77
  78                 string id;
  79                 public string Id {
  80                         get { return id; }
  81                 }
  82
  83                 static TimeZoneInfo local;
  84                 public static TimeZoneInfo Local {
  85                         get {
  86                                 if (local == null) {
  87 #if MONODROID
  88                                         local = ZoneInfoDB.Default;
  89 #elif LIBC
  90                                         try {
  91                                                 local = FindSystemTimeZoneByFileName ("Local", "/etc/localtime");
  92                                         } catch {
  93                                                 try {
  94                                                         local = FindSystemTimeZoneByFileName ("Local", Path.Combine (TimeZoneDirectory, "localtime"));
  95                                                 } catch {
  96                                                         throw new TimeZoneNotFoundException ();
  97                                                 }
  98                                         }
  99 #else
 100                                         throw new TimeZoneNotFoundException ();
 101 #endif
 102                                 }
 103                                 return local;
 104                         }
 105                 }
 106
 107                 string standardDisplayName;
 108                 public string StandardName {
 109                         get { return standardDisplayName; }
 110                 }
 111
 112                 bool disableDaylightSavingTime;
 113                 public bool SupportsDaylightSavingTime {
 114                         get  { return !disableDaylightSavingTime; }
 115                 }
 116
 117                 static TimeZoneInfo utc;
 118                 public static TimeZoneInfo Utc {
 119                         get {
 120                                 if (utc == null)
 121                                         utc = CreateCustomTimeZone ("UTC", new TimeSpan (0), "UTC", "UTC");
 122                                 return utc;
 123                         }
 124                 }
 125 #if LIBC
 126                 static string timeZoneDirectory = null;
 127                 static string TimeZoneDirectory {
 128                         get {
 129                                 if (timeZoneDirectory == null)
 130                                         timeZoneDirectory = "/usr/share/zoneinfo";
 131                                 return timeZoneDirectory;
 132                         }
 133                         set {
 134                                 ClearCachedData ();
 135                                 timeZoneDirectory = value;
 136                         }
 137                 }
 138 #endif
 139                 private AdjustmentRule [] adjustmentRules;
 140
 141 #if !NET_2_1
 142                 static RegistryKey timeZoneKey = null;
 143                 static bool timeZoneKeySet = false;
 144                 static RegistryKey TimeZoneKey {
 145                         get {
 146                                 if (!timeZoneKeySet) {
 147                                         int p = (int) Environment.OSVersion.Platform;
 148                                         /* Only use the registry on non-Unix platforms. */
 149                                         if ((p != 4) && (p != 6) && (p != 128))
 150                                                 timeZoneKey = Registry.LocalMachine.OpenSubKey (
 151                                                         "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
 152                                                         false);
 153                                         timeZoneKeySet = true;
 154                                 }
 155                                 return timeZoneKey;
 156                         }
 157                 }
 158 #endif
 159
 160                 public static void ClearCachedData ()
 161                 {
 162                         local = null;
 163                         utc = null;
 164                         systemTimeZones = null;
 165                 }
 166
 167                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 168                 {
 169                         return ConvertTime (dateTime, TimeZoneInfo.Local, destinationTimeZone);
 170                 }
 171
 172                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)
 173                 {
 174                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 175                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 176
 177                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 178                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 179
 180                         if (sourceTimeZone.IsInvalidTime (dateTime))
 181                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 182
 183                         if (sourceTimeZone == null)
 184                                 throw new ArgumentNullException ("sourceTimeZone");
 185
 186                         if (destinationTimeZone == null)
 187                                 throw new ArgumentNullException ("destinationTimeZone");
 188
 189                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone == TimeZoneInfo.Local && destinationTimeZone == TimeZoneInfo.Local)
 190                                 return dateTime;
 191
 192                         DateTime utc = ConvertTimeToUtc (dateTime);
 193
 194                         if (destinationTimeZone == TimeZoneInfo.Utc)
 195                                 return utc;
 196
 197                         return ConvertTimeFromUtc (utc, destinationTimeZone);
 198
 199                 }
 200
 201                 public static DateTimeOffset ConvertTime (DateTimeOffset dateTimeOffset, TimeZoneInfo destinationTimeZone)
 202                 {
 203                         throw new NotImplementedException ();
 204                 }
 205
 206                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string destinationTimeZoneId)
 207                 {
 208                         return ConvertTime (dateTime, FindSystemTimeZoneById (destinationTimeZoneId));
 209                 }
 210
 211                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string sourceTimeZoneId, string destinationTimeZoneId)
 212                 {
 213                         return ConvertTime (dateTime, FindSystemTimeZoneById (sourceTimeZoneId), FindSystemTimeZoneById (destinationTimeZoneId));
 214                 }
 215
 216                 public static DateTimeOffset ConvertTimeBySystemTimeZoneId (DateTimeOffset dateTimeOffset, string destinationTimeZoneId)
 217                 {
 218                         return ConvertTime (dateTimeOffset, FindSystemTimeZoneById (destinationTimeZoneId));
 219                 }
 220
 221                 private DateTime ConvertTimeFromUtc (DateTime dateTime)
 222                 {
 223                         if (dateTime.Kind == DateTimeKind.Local)
 224                                 throw new ArgumentException ("Kind property of dateTime is Local");
 225
 226                         if (this == TimeZoneInfo.Utc)
 227                                 return DateTime.SpecifyKind (dateTime, DateTimeKind.Utc);
 228
 229                         //FIXME: do not rely on DateTime implementation !
 230                         if (this == TimeZoneInfo.Local)
 231                                 return DateTime.SpecifyKind (dateTime.ToLocalTime (), DateTimeKind.Unspecified);
 232
 233                         AdjustmentRule rule = GetApplicableRule (dateTime);
 234
 235                         if (IsDaylightSavingTime (DateTime.SpecifyKind (dateTime, DateTimeKind.Utc)))
 236                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset + rule.DaylightDelta , DateTimeKind.Unspecified);
 237                         else
 238                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset, DateTimeKind.Unspecified);
 239                 }
 240
 241                 public static DateTime ConvertTimeFromUtc (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 242                 {
 243                         if (destinationTimeZone == null)
 244                                 throw new ArgumentNullException ("destinationTimeZone");
 245
 246                         return destinationTimeZone.ConvertTimeFromUtc (dateTime);
 247                 }
 248
 249                 public static DateTime ConvertTimeToUtc (DateTime dateTime)
 250                 {
 251                         if (dateTime.Kind == DateTimeKind.Utc)
 252                                 return dateTime;
 253
 254                         //FIXME: do not rely on DateTime implementation !
 255                         return DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc);
 256                 }
 257
 258                 public static DateTime ConvertTimeToUtc (DateTime dateTime, TimeZoneInfo sourceTimeZone)
 259                 {
 260                         if (sourceTimeZone == null)
 261                                 throw new ArgumentNullException ("sourceTimeZone");
 262
 263                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 264                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 265
 266                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 267                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 268
 269                         if (sourceTimeZone.IsInvalidTime (dateTime))
 270                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 271
 272                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone == TimeZoneInfo.Utc)
 273                                 return dateTime;
 274
 275                         if (dateTime.Kind == DateTimeKind.Utc)
 276                                 return dateTime;
 277
 278                         if (dateTime.Kind == DateTimeKind.Local)
 279                                 return ConvertTimeToUtc (dateTime);
 280
 281                         if (sourceTimeZone.IsAmbiguousTime (dateTime) || !sourceTimeZone.IsDaylightSavingTime (dateTime))
 282                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 283                         else {
 284                                 AdjustmentRule rule = sourceTimeZone.GetApplicableRule (dateTime);
 285                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset - rule.DaylightDelta, DateTimeKind.Utc);
 286                         }
 287                 }
 288
 289                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName)
 290                 {
 291                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, null, null, true);
 292                 }
 293
 294                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules)
 295                 {
 296                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, false);
 297                 }
 298
 299                 public static TimeZoneInfo CreateCustomTimeZone ( string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 300                 {
 301                         return new TimeZoneInfo (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, disableDaylightSavingTime);
 302                 }
 303
 304                 public bool Equals (TimeZoneInfo other)
 305                 {
 306                         if (other == null)
 307                                 return false;
 308
 309                         return other.Id == this.Id && HasSameRules (other);
 310                 }
 311
 312                 public static TimeZoneInfo FindSystemTimeZoneById (string id)
 313                 {
 314                         //FIXME: this method should check for cached values in systemTimeZones
 315                         if (id == null)
 316                                 throw new ArgumentNullException ("id");
 317 #if !NET_2_1
 318                         if (TimeZoneKey != null)
 319                         {
 320                                 RegistryKey key = TimeZoneKey.OpenSubKey (id, false);
 321                                 if (key == null)
 322                                         throw new TimeZoneNotFoundException ();
 323                                 return FromRegistryKey(id, key);
 324                         }
 325 #endif
 326 #if MONODROID
 327                         return ZoneInfoDB.GetTimeZone (id);
 328 #elif LIBC
 329                         string filepath = Path.Combine (TimeZoneDirectory, id);
 330                         return FindSystemTimeZoneByFileName (id, filepath);
 331 #else
 332                         throw new NotImplementedException ();
 333 #endif
 334                 }
 335
 336 #if LIBC
 337                 const int BUFFER_SIZE = 16384; //Big enough for any tz file (on Oct 2008, all tz files are under 10k)
 338                 private static TimeZoneInfo FindSystemTimeZoneByFileName (string id, string filepath)
 339                 {
 340                         if (!File.Exists (filepath))
 341                                 throw new TimeZoneNotFoundException ();
 342
 343                         byte [] buffer = new byte [BUFFER_SIZE];
 344                         int length;
 345                         using (FileStream stream = File.OpenRead (filepath)) {
 346                                 length = stream.Read (buffer, 0, BUFFER_SIZE);
 347                         }
 348
 349                         if (!ValidTZFile (buffer, length))
 350                                 throw new InvalidTimeZoneException ("TZ file too big for the buffer");
 351
 352                         try {
 353                                 return ParseTZBuffer (id, buffer, length);
 354                         } catch (Exception e) {
 355                                 throw new InvalidTimeZoneException (e.Message);
 356                         }
 357                 }
 358 #endif
 359
 360 #if !NET_2_1
 361                 private static TimeZoneInfo FromRegistryKey (string id, RegistryKey key)
 362                 {
 363                         byte [] reg_tzi = (byte []) key.GetValue ("TZI");
 364
 365                         if (reg_tzi == null)
 366                                 throw new InvalidTimeZoneException ();
 367
 368                         int bias = BitConverter.ToInt32 (reg_tzi, 0);
 369                         TimeSpan baseUtcOffset = new TimeSpan (0, -bias, 0);
 370
 371                         string display_name = (string) key.GetValue ("Display");
 372                         string standard_name = (string) key.GetValue ("Std");
 373                         string daylight_name = (string) key.GetValue ("Dlt");
 374
 375                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 376
 377                         RegistryKey dst_key = key.OpenSubKey ("Dynamic DST", false);
 378                         if (dst_key != null) {
 379                                 int first_year = (int) dst_key.GetValue ("FirstEntry");
 380                                 int last_year = (int) dst_key.GetValue ("LastEntry");
 381                                 int year;
 382
 383                                 for (year=first_year; year<=last_year; year++) {
 384                                         byte [] dst_tzi = (byte []) dst_key.GetValue (year.ToString ());
 385                                         if (dst_tzi != null) {
 386                                                 int start_year = year == first_year ? 1 : year;
 387                                                 int end_year = year == last_year ? 9999 : year;
 388                                                 ParseRegTzi(adjustmentRules, start_year, end_year, dst_tzi);
 389                                         }
 390                                 }
 391                         }
 392                         else
 393                                 ParseRegTzi(adjustmentRules, 1, 9999, reg_tzi);
 394
 395                         return CreateCustomTimeZone (id, baseUtcOffset, display_name, standard_name, daylight_name, ValidateRules (adjustmentRules).ToArray ());
 396                 }
 397
 398                 private static void ParseRegTzi (List<AdjustmentRule> adjustmentRules, int start_year, int end_year, byte [] buffer)
 399                 {
 400                         //int standard_bias = BitConverter.ToInt32 (buffer, 4); /* not sure how to handle this */
 401                         int daylight_bias = BitConverter.ToInt32 (buffer, 8);
 402
 403                         int standard_year = BitConverter.ToInt16 (buffer, 12);
 404                         int standard_month = BitConverter.ToInt16 (buffer, 14);
 405                         int standard_dayofweek = BitConverter.ToInt16 (buffer, 16);
 406                         int standard_day = BitConverter.ToInt16 (buffer, 18);
 407                         int standard_hour = BitConverter.ToInt16 (buffer, 20);
 408                         int standard_minute = BitConverter.ToInt16 (buffer, 22);
 409                         int standard_second = BitConverter.ToInt16 (buffer, 24);
 410                         int standard_millisecond = BitConverter.ToInt16 (buffer, 26);
 411
 412                         int daylight_year = BitConverter.ToInt16 (buffer, 28);
 413                         int daylight_month = BitConverter.ToInt16 (buffer, 30);
 414                         int daylight_dayofweek = BitConverter.ToInt16 (buffer, 32);
 415                         int daylight_day = BitConverter.ToInt16 (buffer, 34);
 416                         int daylight_hour = BitConverter.ToInt16 (buffer, 36);
 417                         int daylight_minute = BitConverter.ToInt16 (buffer, 38);
 418                         int daylight_second = BitConverter.ToInt16 (buffer, 40);
 419                         int daylight_millisecond = BitConverter.ToInt16 (buffer, 42);
 420
 421                         if (standard_month == 0 || daylight_month == 0)
 422                                 return;
 423
 424                         DateTime start_date;
 425                         DateTime start_timeofday = new DateTime (1, 1, 1, daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 426                         TransitionTime start_transition_time;
 427
 428                         if (daylight_year == 0) {
 429                                 start_date = new DateTime (start_year, 1, 1);
 430                                 start_transition_time = TransitionTime.CreateFloatingDateRule (
 431                                         start_timeofday, daylight_month, daylight_day,
 432                                         (DayOfWeek) daylight_dayofweek);
 433                         }
 434                         else {
 435                                 start_date = new DateTime (daylight_year, daylight_month, daylight_day,
 436                                         daylight_hour, daylight_minute, daylight_second, daylight_millisecond);
 437                                 start_transition_time = TransitionTime.CreateFixedDateRule (
 438                                         start_timeofday, daylight_month, daylight_day);
 439                         }
 440
 441                         DateTime end_date;
 442                         DateTime end_timeofday = new DateTime (1, 1, 1, standard_hour, standard_minute, standard_second, standard_millisecond);
 443                         TransitionTime end_transition_time;
 444
 445                         if (standard_year == 0) {
 446                                 end_date = new DateTime (end_year, 12, 31);
 447                                 end_transition_time = TransitionTime.CreateFloatingDateRule (
 448                                         end_timeofday, standard_month, standard_day,
 449                                         (DayOfWeek) standard_dayofweek);
 450                         }
 451                         else {
 452                                 end_date = new DateTime (standard_year, standard_month, standard_day,
 453                                         standard_hour, standard_minute, standard_second, standard_millisecond);
 454                                 end_transition_time = TransitionTime.CreateFixedDateRule (
 455                                         end_timeofday, standard_month, standard_day);
 456                         }
 457
 458                         TimeSpan daylight_delta = new TimeSpan(0, -daylight_bias, 0);
 459
 460                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (
 461                                 start_date, end_date, daylight_delta,
 462                                 start_transition_time, end_transition_time));
 463                 }
 464 #endif
 465
 466                 public static TimeZoneInfo FromSerializedString (string source)
 467                 {
 468                         throw new NotImplementedException ();
 469                 }
 470
 471                 public AdjustmentRule [] GetAdjustmentRules ()
 472                 {
 473                         if (disableDaylightSavingTime)
 474                                 return new AdjustmentRule [0];
 475                         else
 476                                 return (AdjustmentRule []) adjustmentRules.Clone ();
 477                 }
 478
 479                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTime dateTime)
 480                 {
 481                         if (!IsAmbiguousTime (dateTime))
 482                                 throw new ArgumentException ("dateTime is not an ambiguous time");
 483
 484                         AdjustmentRule rule = GetApplicableRule (dateTime);
 485                         return new TimeSpan[] {baseUtcOffset, baseUtcOffset + rule.DaylightDelta};
 486                 }
 487
 488                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTimeOffset dateTimeOffset)
 489                 {
 490                         if (!IsAmbiguousTime (dateTimeOffset))
 491                                 throw new ArgumentException ("dateTimeOffset is not an ambiguous time");
 492
 493                         throw new NotImplementedException ();
 494                 }
 495
 496                 public override int GetHashCode ()
 497                 {
 498                         int hash_code = Id.GetHashCode ();
 499                         foreach (AdjustmentRule rule in GetAdjustmentRules ())
 500                                 hash_code ^= rule.GetHashCode ();
 501                         return hash_code;
 502                 }
 503
 504 #if NET_4_0
 505                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
 506 #else
 507                 public void GetObjectData (SerializationInfo info, StreamingContext context)
 508 #endif
 509                 {
 510                         throw new NotImplementedException ();
 511                 }
 512
 513                 //FIXME: change this to a generic Dictionary and allow caching for FindSystemTimeZoneById
 514                 private static List<TimeZoneInfo> systemTimeZones = null;
 515                 public static ReadOnlyCollection<TimeZoneInfo> GetSystemTimeZones ()
 516                 {
 517                         if (systemTimeZones == null) {
 518                                 systemTimeZones = new List<TimeZoneInfo> ();
 519 #if !NET_2_1
 520                                 if (TimeZoneKey != null) {
 521                                         foreach (string id in TimeZoneKey.GetSubKeyNames ()) {
 522                                                 try {
 523                                                         systemTimeZones.Add (FindSystemTimeZoneById (id));
 524                                                 } catch {}
 525                                         }
 526
 527                                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 528                                 }
 529 #endif
 530 #if MONODROID
 531                         systemTimeZones.AddRange (ZoneInfoDB.GetAvailableIds ()
 532                                         .Select (id => ZoneInfoDB.GetTimeZone (id)));
 533 #elif LIBC
 534                                 string[] continents = new string [] {"Africa", "America", "Antarctica", "Arctic", "Asia", "Atlantic", "Brazil", "Canada", "Chile", "Europe", "Indian", "Mexico", "Mideast", "Pacific", "US"};
 535                                 foreach (string continent in continents) {
 536                                         try {
 537                                                 foreach (string zonepath in Directory.GetFiles (Path.Combine (TimeZoneDirectory, continent))) {
 538                                                         try {
 539                                                                 string id = String.Format ("{0}/{1}", continent, Path.GetFileName (zonepath));
 540                                                                 systemTimeZones.Add (FindSystemTimeZoneById (id));
 541                                                         } catch (ArgumentNullException) {
 542                                                         } catch (TimeZoneNotFoundException) {
 543                                                         } catch (InvalidTimeZoneException) {
 544                                                         } catch (Exception) {
 545                                                                 throw;
 546                                                         }
 547                                                 }
 548                                         } catch {}
 549                                 }
 550 #else
 551                                 throw new NotImplementedException ("This method is not implemented for this platform");
 552 #endif
 553                         }
 554                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 555                 }
 556
 557                 public TimeSpan GetUtcOffset (DateTime dateTime)
 558                 {
 559                         if (IsDaylightSavingTime (dateTime)) {
 560                                 AdjustmentRule rule = GetApplicableRule (dateTime);
 561                                 return BaseUtcOffset + rule.DaylightDelta;
 562                         }
 563
 564                         return BaseUtcOffset;
 565                 }
 566
 567                 public TimeSpan GetUtcOffset (DateTimeOffset dateTimeOffset)
 568                 {
 569                         throw new NotImplementedException ();
 570                 }
 571
 572                 public bool HasSameRules (TimeZoneInfo other)
 573                 {
 574                         if (other == null)
 575                                 throw new ArgumentNullException ("other");
 576
 577                         if ((this.adjustmentRules == null) != (other.adjustmentRules == null))
 578                                 return false;
 579
 580                         if (this.adjustmentRules == null)
 581                                 return true;
 582
 583                         if (this.BaseUtcOffset != other.BaseUtcOffset)
 584                                 return false;
 585
 586                         if (this.adjustmentRules.Length != other.adjustmentRules.Length)
 587                                 return false;
 588
 589                         for (int i = 0; i < adjustmentRules.Length; i++) {
 590                                 if (! (this.adjustmentRules [i]).Equals (other.adjustmentRules [i]))
 591                                         return false;
 592                         }
 593
 594                         return true;
 595                 }
 596
 597                 public bool IsAmbiguousTime (DateTime dateTime)
 598                 {
 599                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 600                                 throw new ArgumentException ("Kind is Local and time is Invalid");
 601
 602                         if (this == TimeZoneInfo.Utc)
 603                                 return false;
 604
 605                         if (dateTime.Kind == DateTimeKind.Utc)
 606                                 dateTime = ConvertTimeFromUtc (dateTime);
 607
 608                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 609                                 dateTime = ConvertTime (dateTime, TimeZoneInfo.Local, this);
 610
 611                         AdjustmentRule rule = GetApplicableRule (dateTime);
 612                         DateTime tpoint = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year);
 613                         if (dateTime > tpoint - rule.DaylightDelta  && dateTime <= tpoint)
 614                                 return true;
 615
 616                         return false;
 617                 }
 618
 619                 public bool IsAmbiguousTime (DateTimeOffset dateTimeOffset)
 620                 {
 621                         throw new NotImplementedException ();
 622                 }
 623
 624                 public bool IsDaylightSavingTime (DateTime dateTime)
 625                 {
 626                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 627                                 throw new ArgumentException ("dateTime is invalid and Kind is Local");
 628
 629                         if (this == TimeZoneInfo.Utc)
 630                                 return false;
 631
 632                         if (!SupportsDaylightSavingTime)
 633                                 return false;
 634                         //FIXME: do not rely on DateTime implementation !
 635                         if ((dateTime.Kind == DateTimeKind.Local || dateTime.Kind == DateTimeKind.Unspecified) && this == TimeZoneInfo.Local)
 636                                 return dateTime.IsDaylightSavingTime ();
 637
 638                         //FIXME: do not rely on DateTime implementation !
 639                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Utc)
 640                                 return IsDaylightSavingTime (DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc));
 641
 642                         AdjustmentRule rule = GetApplicableRule (dateTime.Date);
 643                         if (rule == null)
 644                                 return false;
 645
 646                         DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 647                         DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
 648                         if (dateTime.Kind == DateTimeKind.Utc) {
 649                                 DST_start -= BaseUtcOffset;
 650                                 DST_end -= (BaseUtcOffset + rule.DaylightDelta);
 651                         }
 652
 653                         return (dateTime >= DST_start && dateTime < DST_end);
 654                 }
 655
 656                 public bool IsDaylightSavingTime (DateTimeOffset dateTimeOffset)
 657                 {
 658                         throw new NotImplementedException ();
 659                 }
 660
 661                 public bool IsInvalidTime (DateTime dateTime)
 662                 {
 663                         if (dateTime.Kind == DateTimeKind.Utc)
 664                                 return false;
 665                         if (dateTime.Kind == DateTimeKind.Local && this != Local)
 666                                 return false;
 667
 668                         AdjustmentRule rule = GetApplicableRule (dateTime);
 669                         DateTime tpoint = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 670                         if (dateTime >= tpoint && dateTime < tpoint + rule.DaylightDelta)
 671                                 return true;
 672
 673                         return false;
 674                 }
 675
 676 #if NET_4_0
 677                 void IDeserializationCallback.OnDeserialization (object sender)
 678 #else
 679                 public void OnDeserialization (object sender)
 680 #endif
 681                 {
 682                         throw new NotImplementedException ();
 683                 }
 684
 685                 public string ToSerializedString ()
 686                 {
 687                         throw new NotImplementedException ();
 688                 }
 689
 690                 public override string ToString ()
 691                 {
 692                         return DisplayName;
 693                 }
 694
 695                 private TimeZoneInfo (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 696                 {
 697                         if (id == null)
 698                                 throw new ArgumentNullException ("id");
 699
 700                         if (id == String.Empty)
 701                                 throw new ArgumentException ("id parameter is an empty string");
 702
 703                         if (baseUtcOffset.Ticks % TimeSpan.TicksPerMinute != 0)
 704                                 throw new ArgumentException ("baseUtcOffset parameter does not represent a whole number of minutes");
 705
 706                         if (baseUtcOffset > new TimeSpan (14, 0, 0) || baseUtcOffset < new TimeSpan (-14, 0, 0))
 707                                 throw new ArgumentOutOfRangeException ("baseUtcOffset parameter is greater than 14 hours or less than -14 hours");
 708
 709 #if STRICT
 710                         if (id.Length > 32)
 711                                 throw new ArgumentException ("id parameter shouldn't be longer than 32 characters");
 712 #endif
 713
 714                         if (adjustmentRules != null && adjustmentRules.Length != 0) {
 715                                 AdjustmentRule prev = null;
 716                                 foreach (AdjustmentRule current in adjustmentRules) {
 717                                         if (current == null)
 718                                                 throw new InvalidTimeZoneException ("one or more elements in adjustmentRules are null");
 719
 720                                         if ((baseUtcOffset + current.DaylightDelta < new TimeSpan (-14, 0, 0)) ||
 721                                                         (baseUtcOffset + current.DaylightDelta > new TimeSpan (14, 0, 0)))
 722                                                 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;");
 723
 724                                         if (prev != null && prev.DateStart > current.DateStart)
 725                                                 throw new InvalidTimeZoneException ("adjustment rules specified in adjustmentRules parameter are not in chronological order");
 726
 727                                         if (prev != null && prev.DateEnd > current.DateStart)
 728                                                 throw new InvalidTimeZoneException ("some adjustment rules in the adjustmentRules parameter overlap");
 729
 730                                         if (prev != null && prev.DateEnd == current.DateStart)
 731                                                 throw new InvalidTimeZoneException ("a date can have multiple adjustment rules applied to it");
 732
 733                                         prev = current;
 734                                 }
 735                         }
 736
 737                         this.id = id;
 738                         this.baseUtcOffset = baseUtcOffset;
 739                         this.displayName = displayName ?? id;
 740                         this.standardDisplayName = standardDisplayName ?? id;
 741                         this.daylightDisplayName = daylightDisplayName;
 742                         this.disableDaylightSavingTime = disableDaylightSavingTime;
 743                         this.adjustmentRules = adjustmentRules;
 744                 }
 745
 746                 private AdjustmentRule GetApplicableRule (DateTime dateTime)
 747                 {
 748                         //Transitions are always in standard time
 749                         DateTime date = dateTime;
 750
 751                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 752                                 date = date.ToUniversalTime () + BaseUtcOffset;
 753
 754                         if (dateTime.Kind == DateTimeKind.Utc && this != TimeZoneInfo.Utc)
 755                                 date = date + BaseUtcOffset;
 756
 757                         if (adjustmentRules != null) {
 758                                 foreach (AdjustmentRule rule in adjustmentRules) {
 759                                         if (rule.DateStart > date.Date)
 760                                                 return null;
 761                                         if (rule.DateEnd < date.Date)
 762                                                 continue;
 763                                         return rule;
 764                                 }
 765                         }
 766                         return null;
 767                 }
 768
 769                 private static DateTime TransitionPoint (TransitionTime transition, int year)
 770                 {
 771                         if (transition.IsFixedDateRule)
 772                                 return new DateTime (year, transition.Month, transition.Day) + transition.TimeOfDay.TimeOfDay;
 773
 774                         DayOfWeek first = (new DateTime (year, transition.Month, 1)).DayOfWeek;
 775                         int day = 1 + (transition.Week - 1) * 7 + (transition.DayOfWeek - first) % 7;
 776                         if (day >  DateTime.DaysInMonth (year, transition.Month))
 777                                 day -= 7;
 778                         return new DateTime (year, transition.Month, day) + transition.TimeOfDay.TimeOfDay;
 779                 }
 780
 781                 static List<AdjustmentRule> ValidateRules (List<AdjustmentRule> adjustmentRules)
 782                 {
 783                         AdjustmentRule prev = null;
 784                         foreach (AdjustmentRule current in adjustmentRules.ToArray ()) {
 785                                 if (prev != null && prev.DateEnd > current.DateStart) {
 786                                         adjustmentRules.Remove (current);
 787                                 }
 788                                 prev = current;
 789                         }
 790                         return adjustmentRules;
 791                 }
 792
 793 #if LIBC || MONODROID
 794                 private static bool ValidTZFile (byte [] buffer, int length)
 795                 {
 796                         StringBuilder magic = new StringBuilder ();
 797
 798                         for (int i = 0; i < 4; i++)
 799                                 magic.Append ((char)buffer [i]);
 800
 801                         if (magic.ToString () != "TZif")
 802                                 return false;
 803
 804                         if (length >= BUFFER_SIZE)
 805                                 return false;
 806
 807                         return true;
 808                 }
 809
 810                 struct TimeType
 811                 {
 812                         public readonly int Offset;
 813                         public readonly bool IsDst;
 814                         public string Name;
 815
 816                         public TimeType (int offset, bool is_dst, string abbrev)
 817                         {
 818                                 this.Offset = offset;
 819                                 this.IsDst = is_dst;
 820                                 this.Name = abbrev;
 821                         }
 822
 823                         public override string ToString ()
 824                         {
 825                                 return "offset: " + Offset + "s, is_dst: " + IsDst + ", zone name: " + Name;
 826                         }
 827                 }
 828
 829                 static int SwapInt32 (int i)
 830                 {
 831                         return (((i >> 24) & 0xff)
 832                                 | ((i >> 8) & 0xff00)
 833                                 | ((i << 8) & 0xff0000)
 834                                 | ((i << 24)));
 835                 }
 836
 837                 static int ReadBigEndianInt32 (byte [] buffer, int start)
 838                 {
 839                         int i = BitConverter.ToInt32 (buffer, start);
 840                         if (!BitConverter.IsLittleEndian)
 841                                 return i;
 842
 843                         return SwapInt32 (i);
 844                 }
 845
 846                 private static TimeZoneInfo ParseTZBuffer (string id, byte [] buffer, int length)
 847                 {
 848                         //Reading the header. 4 bytes for magic, 16 are reserved
 849                         int ttisgmtcnt = ReadBigEndianInt32 (buffer, 20);
 850                         int ttisstdcnt = ReadBigEndianInt32 (buffer, 24);
 851                         int leapcnt = ReadBigEndianInt32 (buffer, 28);
 852                         int timecnt = ReadBigEndianInt32 (buffer, 32);
 853                         int typecnt = ReadBigEndianInt32 (buffer, 36);
 854                         int charcnt = ReadBigEndianInt32 (buffer, 40);
 855
 856                         if (length < 44 + timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt)
 857                                 throw new InvalidTimeZoneException ();
 858
 859                         Dictionary<int, string> abbreviations = ParseAbbreviations (buffer, 44 + 4 * timecnt + timecnt + 6 * typecnt, charcnt);
 860                         Dictionary<int, TimeType> time_types = ParseTimesTypes (buffer, 44 + 4 * timecnt + timecnt, typecnt, abbreviations);
 861                         List<KeyValuePair<DateTime, TimeType>> transitions = ParseTransitions (buffer, 44, timecnt, time_types);
 862
 863                         if (time_types.Count == 0)
 864                                 throw new InvalidTimeZoneException ();
 865
 866                         if (time_types.Count == 1 && ((TimeType)time_types[0]).IsDst)
 867                                 throw new InvalidTimeZoneException ();
 868
 869                         TimeSpan baseUtcOffset = new TimeSpan (0);
 870                         TimeSpan dstDelta = new TimeSpan (0);
 871                         string standardDisplayName = null;
 872                         string daylightDisplayName = null;
 873                         bool dst_observed = false;
 874                         DateTime dst_start = DateTime.MinValue;
 875                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 876
 877                         for (int i = 0; i < transitions.Count; i++) {
 878                                 var pair = transitions [i];
 879                                 DateTime ttime = pair.Key;
 880                                 TimeType ttype = pair.Value;
 881                                 if (!ttype.IsDst) {
 882                                         if (standardDisplayName != ttype.Name || baseUtcOffset.TotalSeconds != ttype.Offset) {
 883                                                 standardDisplayName = ttype.Name;
 884                                                 daylightDisplayName = null;
 885                                                 baseUtcOffset = new TimeSpan (0, 0, ttype.Offset);
 886                                                 adjustmentRules = new List<AdjustmentRule> ();
 887                                                 dst_observed = false;
 888                                         }
 889                                         if (dst_observed) {
 890                                                 //FIXME: check additional fields for this:
 891                                                 //most of the transitions are expressed in GMT
 892                                                 dst_start += baseUtcOffset;
 893                                                 DateTime dst_end = ttime + baseUtcOffset + dstDelta;
 894
 895                                                 //some weird timezone (America/Phoenix) have end dates on Jan 1st
 896                                                 if (dst_end.Date == new DateTime (dst_end.Year, 1, 1) && dst_end.Year > dst_start.Year)
 897                                                         dst_end -= new TimeSpan (24, 0, 0);
 898
 899                                                 DateTime dateStart, dateEnd;
 900                                                 if (dst_start.Month < 7)
 901                                                         dateStart = new DateTime (dst_start.Year, 1, 1);
 902                                                 else
 903                                                         dateStart = new DateTime (dst_start.Year, 7, 1);
 904
 905                                                 if (dst_end.Month >= 7)
 906                                                         dateEnd = new DateTime (dst_end.Year, 12, 31);
 907                                                 else
 908                                                         dateEnd = new DateTime (dst_end.Year, 6, 30);
 909
 910
 911                                                 TransitionTime transition_start = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_start.TimeOfDay, dst_start.Month, dst_start.Day);
 912                                                 TransitionTime transition_end = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_end.TimeOfDay, dst_end.Month, dst_end.Day);
 913                                                 if  (transition_start != transition_end) //y, that happened in Argentina in 1943-1946
 914                                                         adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (dateStart, dateEnd, dstDelta, transition_start, transition_end));
 915                                         }
 916                                         dst_observed = false;
 917                                 } else {
 918                                         if (daylightDisplayName != ttype.Name || dstDelta.TotalSeconds != ttype.Offset - baseUtcOffset.TotalSeconds) {
 919                                                 daylightDisplayName = ttype.Name;
 920                                                 dstDelta = new TimeSpan(0, 0, ttype.Offset) - baseUtcOffset;
 921                                         }
 922                                         dst_start = ttime;
 923                                         dst_observed = true;
 924                                 }
 925                         }
 926
 927                         if (adjustmentRules.Count == 0) {
 928                                 TimeType t = (TimeType)time_types [0];
 929                                 if (standardDisplayName == null) {
 930                                         standardDisplayName = t.Name;
 931                                         baseUtcOffset = new TimeSpan (0, 0, t.Offset);
 932                                 }
 933                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName);
 934                         } else {
 935                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName, daylightDisplayName, ValidateRules (adjustmentRules).ToArray ());
 936                         }
 937                 }
 938
 939                 static Dictionary<int, string> ParseAbbreviations (byte [] buffer, int index, int count)
 940                 {
 941                         var abbrevs = new Dictionary<int, string> ();
 942                         int abbrev_index = 0;
 943                         var sb = new StringBuilder ();
 944                         for (int i = 0; i < count; i++) {
 945                                 char c = (char) buffer [index + i];
 946                                 if (c != '\0')
 947                                         sb.Append (c);
 948                                 else {
 949                                         abbrevs.Add (abbrev_index, sb.ToString ());
 950                                         //Adding all the substrings too, as it seems to be used, at least for Africa/Windhoek
 951                                         for (int j = 1; j < sb.Length; j++)
 952                                                 abbrevs.Add (abbrev_index + j, sb.ToString (j, sb.Length - j));
 953                                         abbrev_index = i + 1;
 954                                         sb = new StringBuilder ();
 955                                 }
 956                         }
 957                         return abbrevs;
 958                 }
 959
 960                 static Dictionary<int, TimeType> ParseTimesTypes (byte [] buffer, int index, int count, Dictionary<int, string> abbreviations)
 961                 {
 962                         var types = new Dictionary<int, TimeType> (count);
 963                         for (int i = 0; i < count; i++) {
 964                                 int offset = ReadBigEndianInt32 (buffer, index + 6 * i);
 965                                 byte is_dst = buffer [index + 6 * i + 4];
 966                                 byte abbrev = buffer [index + 6 * i + 5];
 967                                 types.Add (i, new TimeType (offset, (is_dst != 0), abbreviations [(int)abbrev]));
 968                         }
 969                         return types;
 970                 }
 971
 972                 static List<KeyValuePair<DateTime, TimeType>> ParseTransitions (byte [] buffer, int index, int count, Dictionary<int, TimeType> time_types)
 973                 {
 974                         var list = new List<KeyValuePair<DateTime, TimeType>> (count);
 975                         for (int i = 0; i < count; i++) {
 976                                 int unixtime = ReadBigEndianInt32 (buffer, index + 4 * i);
 977                                 DateTime ttime = DateTimeFromUnixTime (unixtime);
 978                                 byte ttype = buffer [index + 4 * count + i];
 979                                 list.Add (new KeyValuePair<DateTime, TimeType> (ttime, time_types [(int)ttype]));
 980                         }
 981                         return list;
 982                 }
 983
 984                 static DateTime DateTimeFromUnixTime (long unix_time)
 985                 {
 986                         DateTime date_time = new DateTime (1970, 1, 1);
 987                         return date_time.AddSeconds (unix_time);
 988                 }
 989 #endif
 990         }
 991 }
 992
 993 #endif