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