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.Collections.Generic;
  28 using System.Collections.ObjectModel;
  29 using System.Runtime.Serialization;
  30 using System.Text;
  31
  32 #if LIBC
  33 using System.IO;
  34 using Mono;
  35 #endif
  36
  37 namespace System
  38 {
  39         [SerializableAttribute]
  40         public sealed partial class TimeZoneInfo : IEquatable<TimeZoneInfo>, ISerializable, IDeserializationCallback
  41         {
  42                 TimeSpan baseUtcOffset;
  43                 public TimeSpan BaseUtcOffset {
  44                         get { return baseUtcOffset; }
  45                 }
  46
  47                 string daylightDisplayName;
  48                 public string DaylightName {
  49                         get {
  50                                 if (disableDaylightSavingTime)
  51                                         return String.Empty;
  52                                 return daylightDisplayName;
  53                         }
  54                 }
  55
  56                 string displayName;
  57                 public string DisplayName {
  58                         get { return displayName; }
  59                 }
  60
  61                 string id;
  62                 public string Id {
  63                         get { return id; }
  64                 }
  65
  66                 static TimeZoneInfo local;
  67                 public static TimeZoneInfo Local {
  68                         get {
  69                                 if (local == null) {
  70 #if LIBC
  71                                         try {
  72                                                 local = FindSystemTimeZoneByFileName ("Local", "/etc/localtime");
  73                                         } catch {
  74                                                 try {
  75                                                         local = FindSystemTimeZoneByFileName ("Local", Path.Combine (TimeZoneDirectory, "localtime"));
  76                                                 } catch {
  77                                                         throw new TimeZoneNotFoundException ();
  78                                                 }
  79                                         }
  80 #else
  81                                         throw new TimeZoneNotFoundException ();
  82 #endif
  83                                 }
  84                                 return local;
  85                         }
  86                 }
  87
  88                 string standardDisplayName;
  89                 public string StandardName {
  90                         get { return standardDisplayName; }
  91                 }
  92
  93                 bool disableDaylightSavingTime;
  94                 public bool SupportsDaylightSavingTime {
  95                         get  { return !disableDaylightSavingTime; }
  96                 }
  97
  98                 static TimeZoneInfo utc;
  99                 public static TimeZoneInfo Utc {
 100                         get {
 101                                 if (utc == null)
 102                                         utc = CreateCustomTimeZone ("UTC", new TimeSpan (0), "UTC", "UTC");
 103                                 return utc;
 104                         }
 105                 }
 106 #if LIBC
 107                 static string timeZoneDirectory = null;
 108                 public static string TimeZoneDirectory {
 109                         get {
 110                                 if (timeZoneDirectory == null)
 111                                         timeZoneDirectory = "/usr/share/zoneinfo";
 112                                 return timeZoneDirectory;
 113                         }
 114                         set {
 115                                 ClearCachedData ();
 116                                 timeZoneDirectory = value;
 117                         }
 118                 }
 119 #endif
 120                 private AdjustmentRule [] adjustmentRules;
 121
 122                 public static void ClearCachedData ()
 123                 {
 124                         local = null;
 125                         utc = null;
 126                         systemTimeZones = null;
 127                 }
 128
 129                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 130                 {
 131                         return ConvertTime (dateTime, TimeZoneInfo.Local, destinationTimeZone);
 132                 }
 133
 134                 public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)
 135                 {
 136                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 137                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 138
 139                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 140                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 141
 142                         if (sourceTimeZone.IsInvalidTime (dateTime))
 143                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 144
 145                         if (sourceTimeZone == null)
 146                                 throw new ArgumentNullException ("sourceTimeZone");
 147
 148                         if (destinationTimeZone == null)
 149                                 throw new ArgumentNullException ("destinationTimeZone");
 150
 151                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone == TimeZoneInfo.Local && destinationTimeZone == TimeZoneInfo.Local)
 152                                 return dateTime;
 153
 154                         DateTime utc = ConvertTimeToUtc (dateTime);
 155
 156                         if (destinationTimeZone == TimeZoneInfo.Utc)
 157                                 return utc;
 158
 159                         return ConvertTimeFromUtc (utc, destinationTimeZone);
 160
 161                 }
 162
 163                 public static DateTimeOffset ConvertTime (DateTimeOffset dateTimeOffset, TimeZoneInfo destinationTimeZone)
 164                 {
 165                         throw new NotImplementedException ();
 166                 }
 167
 168                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string destinationTimeZoneId)
 169                 {
 170                         return ConvertTime (dateTime, FindSystemTimeZoneById (destinationTimeZoneId));
 171                 }
 172
 173                 public static DateTime ConvertTimeBySystemTimeZoneId (DateTime dateTime, string sourceTimeZoneId, string destinationTimeZoneId)
 174                 {
 175                         return ConvertTime (dateTime, FindSystemTimeZoneById (sourceTimeZoneId), FindSystemTimeZoneById (destinationTimeZoneId));
 176                 }
 177
 178                 public static DateTimeOffset ConvertTimeBySystemTimeZoneId (DateTimeOffset dateTimeOffset, string destinationTimeZoneId)
 179                 {
 180                         return ConvertTime (dateTimeOffset, FindSystemTimeZoneById (destinationTimeZoneId));
 181                 }
 182
 183                 private DateTime ConvertTimeFromUtc (DateTime dateTime)
 184                 {
 185                         if (dateTime.Kind == DateTimeKind.Local)
 186                                 throw new ArgumentException ("Kind property of dateTime is Local");
 187
 188                         if (this == TimeZoneInfo.Utc)
 189                                 return DateTime.SpecifyKind (dateTime, DateTimeKind.Utc);
 190
 191                         //FIXME: do not rely on DateTime implementation !
 192                         if (this == TimeZoneInfo.Local)
 193                                 return DateTime.SpecifyKind (dateTime.ToLocalTime (), DateTimeKind.Unspecified);
 194
 195                         AdjustmentRule rule = GetApplicableRule (dateTime);
 196
 197                         if (IsDaylightSavingTime (DateTime.SpecifyKind (dateTime, DateTimeKind.Utc)))
 198                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset + rule.DaylightDelta , DateTimeKind.Unspecified);
 199                         else
 200                                 return DateTime.SpecifyKind (dateTime + BaseUtcOffset, DateTimeKind.Unspecified);
 201                 }
 202
 203                 public static DateTime ConvertTimeFromUtc (DateTime dateTime, TimeZoneInfo destinationTimeZone)
 204                 {
 205                         if (destinationTimeZone == null)
 206                                 throw new ArgumentNullException ("destinationTimeZone");
 207
 208                         return destinationTimeZone.ConvertTimeFromUtc (dateTime);
 209                 }
 210
 211                 public static DateTime ConvertTimeToUtc (DateTime dateTime)
 212                 {
 213                         if (dateTime.Kind == DateTimeKind.Utc)
 214                                 return dateTime;
 215
 216                         //FIXME: do not rely on DateTime implementation !
 217                         return DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc);
 218                 }
 219
 220                 public static DateTime ConvertTimeToUtc (DateTime dateTime, TimeZoneInfo sourceTimeZone)
 221                 {
 222                         if (sourceTimeZone == null)
 223                                 throw new ArgumentNullException ("sourceTimeZone");
 224
 225                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
 226                                 throw new ArgumentException ("Kind propery of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
 227
 228                         if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
 229                                 throw new ArgumentException ("Kind propery of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 230
 231                         if (sourceTimeZone.IsInvalidTime (dateTime))
 232                                 throw new ArgumentException ("dateTime parameter is an invalid time");
 233
 234                         if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone == TimeZoneInfo.Utc)
 235                                 return dateTime;
 236
 237                         if (dateTime.Kind == DateTimeKind.Utc)
 238                                 return dateTime;
 239
 240                         if (dateTime.Kind == DateTimeKind.Local)
 241                                 return ConvertTimeToUtc (dateTime);
 242
 243                         if (sourceTimeZone.IsAmbiguousTime (dateTime) || !sourceTimeZone.IsDaylightSavingTime (dateTime))
 244                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset, DateTimeKind.Utc);
 245                         else {
 246                                 AdjustmentRule rule = sourceTimeZone.GetApplicableRule (dateTime);
 247                                 return DateTime.SpecifyKind (dateTime - sourceTimeZone.BaseUtcOffset - rule.DaylightDelta, DateTimeKind.Utc);
 248                         }
 249                 }
 250
 251                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName)
 252                 {
 253                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, null, null, true);
 254                 }
 255
 256                 public static TimeZoneInfo CreateCustomTimeZone (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules)
 257                 {
 258                         return CreateCustomTimeZone (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, false);
 259                 }
 260
 261                 public static TimeZoneInfo CreateCustomTimeZone ( string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 262                 {
 263                         return new TimeZoneInfo (id, baseUtcOffset, displayName, standardDisplayName, daylightDisplayName, adjustmentRules, disableDaylightSavingTime);
 264                 }
 265
 266                 public bool Equals (TimeZoneInfo other)
 267                 {
 268                         if (other == null)
 269                                 return false;
 270
 271                         return other.Id == this.Id && HasSameRules (other);
 272                 }
 273
 274                 public static TimeZoneInfo FindSystemTimeZoneById (string id)
 275                 {
 276                         //FIXME: this method should check for cached values in systemTimeZones
 277                         if (id == null)
 278                                 throw new ArgumentNullException ("id");
 279 #if LIBC
 280                         string filepath = Path.Combine (TimeZoneDirectory, id);
 281                         return FindSystemTimeZoneByFileName (id, filepath);
 282 #else
 283                         throw new NotImplementedException ();
 284 #endif
 285                 }
 286
 287 #if LIBC
 288                 const int BUFFER_SIZE = 8192; //Big enough for any tz file
 289                 private static TimeZoneInfo FindSystemTimeZoneByFileName (string id, string filepath)
 290                 {
 291                         if (!File.Exists (filepath))
 292                                 throw new TimeZoneNotFoundException ();
 293
 294                         byte [] buffer = new byte [BUFFER_SIZE];
 295                         int length;
 296                         using (FileStream stream = File.OpenRead (filepath)) {
 297                                 length = stream.Read (buffer, 0, BUFFER_SIZE);
 298                         }
 299
 300                         if (!ValidTZFile (buffer, length))
 301                                 throw new InvalidTimeZoneException ();
 302
 303                         try {
 304                                 return ParseTZBuffer (id, buffer, length);
 305                         } catch (Exception e) {
 306                                 throw new InvalidTimeZoneException (e.Message);
 307                         }
 308                 }
 309 #endif
 310
 311                 public static TimeZoneInfo FromSerializedString (string source)
 312                 {
 313                         throw new NotImplementedException ();
 314                 }
 315
 316                 public AdjustmentRule [] GetAdjustmentRules ()
 317                 {
 318                         if (disableDaylightSavingTime)
 319                                 return new AdjustmentRule [0];
 320                         else
 321                                 return (AdjustmentRule []) adjustmentRules.Clone ();
 322                 }
 323
 324                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTime dateTime)
 325                 {
 326                         if (!IsAmbiguousTime (dateTime))
 327                                 throw new ArgumentException ("dateTime is not an ambiguous time");
 328
 329                         AdjustmentRule rule = GetApplicableRule (dateTime);
 330                         return new TimeSpan[] {baseUtcOffset, baseUtcOffset + rule.DaylightDelta};
 331                 }
 332
 333                 public TimeSpan [] GetAmbiguousTimeOffsets (DateTimeOffset dateTimeOffset)
 334                 {
 335                         if (!IsAmbiguousTime (dateTimeOffset))
 336                                 throw new ArgumentException ("dateTimeOffset is not an ambiguous time");
 337
 338                         throw new NotImplementedException ();
 339                 }
 340
 341                 public override int GetHashCode ()
 342                 {
 343                         int hash_code = Id.GetHashCode ();
 344                         foreach (AdjustmentRule rule in GetAdjustmentRules ())
 345                                 hash_code ^= rule.GetHashCode ();
 346                         return hash_code;
 347                 }
 348
 349                 public void GetObjectData (SerializationInfo info, StreamingContext context)
 350                 {
 351                         throw new NotImplementedException ();
 352                 }
 353
 354                 //FIXME: change this to a generic Dictionary and allow caching for FindSystemTimeZoneById
 355                 private static List<TimeZoneInfo> systemTimeZones = null;
 356                 public static ReadOnlyCollection<TimeZoneInfo> GetSystemTimeZones ()
 357                 {
 358                         if (systemTimeZones == null) {
 359                                 systemTimeZones = new List<TimeZoneInfo> ();
 360 #if LIBC
 361                                 string[] continents = new string [] {"Africa", "America", "Antarctica", "Arctic", "Asia", "Atlantic", "Brazil", "Canada", "Chile", "Europe", "Indian", "Mexico", "Mideast", "Pacific", "US"};
 362                                 foreach (string continent in continents) {
 363                                         try {
 364                                                 foreach (string zonepath in Directory.GetFiles (Path.Combine (TimeZoneDirectory, continent))) {
 365                                                         try {
 366                                                                 string id = String.Format ("{0}/{1}", continent, Path.GetFileName (zonepath));
 367                                                                 systemTimeZones.Add (FindSystemTimeZoneById (id));
 368                                                         } catch (ArgumentNullException) {
 369                                                         } catch (TimeZoneNotFoundException) {
 370                                                         } catch (InvalidTimeZoneException) {
 371                                                         } catch (Exception e) {
 372                                                                 if (e is OutOfMemoryException || e is System.Security.SecurityException)
 373                                                                         throw;
 374                                                                 else {
 375                                                                         Console.WriteLine ("Unexpected Exception");
 376                                                                         throw;
 377                                                                 }
 378                                                         }
 379                                                 }
 380                                         } catch {}
 381                                 }
 382 #else
 383                                 throw new NotImplementedException ("This method is not implemented for this platform");
 384 #endif
 385                         }
 386                         return new ReadOnlyCollection<TimeZoneInfo> (systemTimeZones);
 387                 }
 388
 389                 public TimeSpan GetUtcOffset (DateTime dateTime)
 390                 {
 391                         if (IsDaylightSavingTime (dateTime)) {
 392                                 AdjustmentRule rule = GetApplicableRule (dateTime);
 393                                 return BaseUtcOffset + rule.DaylightDelta;
 394                         }
 395
 396                         return BaseUtcOffset;
 397                 }
 398
 399                 public TimeSpan GetUtcOffset (DateTimeOffset dateTimeOffset)
 400                 {
 401                         throw new NotImplementedException ();
 402                 }
 403
 404                 public bool HasSameRules (TimeZoneInfo other)
 405                 {
 406                         if (other == null)
 407                                 throw new ArgumentNullException ("other");
 408
 409                         if ((this.adjustmentRules == null) != (other.adjustmentRules == null))
 410                                 return false;
 411
 412                         if (this.adjustmentRules == null)
 413                                 return true;
 414
 415                         if (this.BaseUtcOffset != other.BaseUtcOffset)
 416                                 return false;
 417
 418                         if (this.adjustmentRules.Length != other.adjustmentRules.Length)
 419                                 return false;
 420
 421                         for (int i = 0; i < adjustmentRules.Length; i++) {
 422                                 if (! (this.adjustmentRules [i]).Equals (other.adjustmentRules [i]))
 423                                         return false;
 424                         }
 425
 426                         return true;
 427                 }
 428
 429                 public bool IsAmbiguousTime (DateTime dateTime)
 430                 {
 431                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 432                                 throw new ArgumentException ("Kind is Local and time is Invalid");
 433
 434                         if (this == TimeZoneInfo.Utc)
 435                                 return false;
 436
 437                         if (dateTime.Kind == DateTimeKind.Utc)
 438                                 dateTime = ConvertTimeFromUtc (dateTime);
 439
 440                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 441                                 dateTime = ConvertTime (dateTime, TimeZoneInfo.Local, this);
 442
 443                         AdjustmentRule rule = GetApplicableRule (dateTime);
 444                         DateTime tpoint = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year);
 445                         if (dateTime > tpoint - rule.DaylightDelta  && dateTime <= tpoint)
 446                                 return true;
 447
 448                         return false;
 449                 }
 450
 451                 public bool IsAmbiguousTime (DateTimeOffset dateTimeOffset)
 452                 {
 453                         throw new NotImplementedException ();
 454                 }
 455
 456                 public bool IsDaylightSavingTime (DateTime dateTime)
 457                 {
 458                         if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
 459                                 throw new ArgumentException ("dateTime is invalid and Kind is Local");
 460
 461                         if (this == TimeZoneInfo.Utc)
 462                                 return false;
 463
 464                         if (!SupportsDaylightSavingTime)
 465                                 return false;
 466                         //FIXME: do not rely on DateTime implementation !
 467                         if ((dateTime.Kind == DateTimeKind.Local || dateTime.Kind == DateTimeKind.Unspecified) && this == TimeZoneInfo.Local)
 468                                 return dateTime.IsDaylightSavingTime ();
 469
 470                         //FIXME: do not rely on DateTime implementation !
 471                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Utc)
 472                                 return IsDaylightSavingTime (DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc));
 473
 474                         AdjustmentRule rule = GetApplicableRule (dateTime.Date);
 475                         if (rule == null)
 476                                 return false;
 477
 478                         DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 479                         DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
 480                         if (dateTime.Kind == DateTimeKind.Utc) {
 481                                 DST_start -= BaseUtcOffset;
 482                                 DST_end -= (BaseUtcOffset + rule.DaylightDelta);
 483                         }
 484
 485                         return (dateTime >= DST_start && dateTime < DST_end);
 486                 }
 487
 488                 public bool IsDaylightSavingTime (DateTimeOffset dateTimeOffset)
 489                 {
 490                         throw new NotImplementedException ();
 491                 }
 492
 493                 public bool IsInvalidTime (DateTime dateTime)
 494                 {
 495                         if (dateTime.Kind == DateTimeKind.Utc)
 496                                 return false;
 497                         if (dateTime.Kind == DateTimeKind.Local && this != Local)
 498                                 return false;
 499
 500                         AdjustmentRule rule = GetApplicableRule (dateTime);
 501                         DateTime tpoint = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
 502                         if (dateTime >= tpoint && dateTime < tpoint + rule.DaylightDelta)
 503                                 return true;
 504
 505                         return false;
 506                 }
 507
 508                 public void OnDeserialization (object sender)
 509                 {
 510                         throw new NotImplementedException ();
 511                 }
 512
 513                 public string ToSerializedString ()
 514                 {
 515                         throw new NotImplementedException ();
 516                 }
 517
 518                 public override string ToString ()
 519                 {
 520                         return DisplayName;
 521                 }
 522
 523                 private TimeZoneInfo (string id, TimeSpan baseUtcOffset, string displayName, string standardDisplayName, string daylightDisplayName, TimeZoneInfo.AdjustmentRule [] adjustmentRules, bool disableDaylightSavingTime)
 524                 {
 525                         if (id == null)
 526                                 throw new ArgumentNullException ("id");
 527
 528                         if (id == String.Empty)
 529                                 throw new ArgumentException ("id parameter is an empty string");
 530
 531                         if (baseUtcOffset.Ticks % TimeSpan.TicksPerMinute != 0)
 532                                 throw new ArgumentException ("baseUtcOffset parameter does not represent a whole number of minutes");
 533
 534                         if (baseUtcOffset > new TimeSpan (14, 0, 0) || baseUtcOffset < new TimeSpan (-14, 0, 0))
 535                                 throw new ArgumentOutOfRangeException ("baseUtcOffset parameter is greater than 14 hours or less than -14 hours");
 536
 537 #if STRICT
 538                         if (id.Length > 32)
 539                                 throw new ArgumentException ("id parameter shouldn't be longer than 32 characters");
 540 #endif
 541
 542                         if (adjustmentRules != null && adjustmentRules.Length != 0) {
 543                                 AdjustmentRule prev = null;
 544                                 foreach (AdjustmentRule current in adjustmentRules) {
 545                                         if (current == null)
 546                                                 throw new InvalidTimeZoneException ("one or more elements in adjustmentRules are null");
 547
 548                                         if ((baseUtcOffset + current.DaylightDelta < new TimeSpan (-14, 0, 0)) ||
 549                                                         (baseUtcOffset + current.DaylightDelta > new TimeSpan (14, 0, 0)))
 550                                                 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;");
 551
 552                                         if (prev != null && prev.DateStart > current.DateStart)
 553                                                 throw new InvalidTimeZoneException ("adjustment rules specified in adjustmentRules parameter are not in chronological order");
 554
 555                                         if (prev != null && prev.DateEnd > current.DateStart)
 556                                                 throw new InvalidTimeZoneException ("some adjustment rules in the adjustmentRules parameter overlap");
 557
 558                                         if (prev != null && prev.DateEnd == current.DateStart)
 559                                                 throw new InvalidTimeZoneException ("a date can have multiple adjustment rules applied to it");
 560
 561                                         prev = current;
 562                                 }
 563                         }
 564
 565                         this.id = id;
 566                         this.baseUtcOffset = baseUtcOffset;
 567                         this.displayName = displayName ?? id;
 568                         this.standardDisplayName = standardDisplayName ?? id;
 569                         this.daylightDisplayName = daylightDisplayName;
 570                         this.disableDaylightSavingTime = disableDaylightSavingTime;
 571                         this.adjustmentRules = adjustmentRules;
 572                 }
 573
 574                 private AdjustmentRule GetApplicableRule (DateTime dateTime)
 575                 {
 576                         //Transitions are always in standard time
 577                         DateTime date = dateTime;
 578
 579                         if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Local)
 580                                 date = date.ToUniversalTime () + BaseUtcOffset;
 581
 582                         if (dateTime.Kind == DateTimeKind.Utc && this != TimeZoneInfo.Utc)
 583                                 date = date + BaseUtcOffset;
 584
 585                         foreach (AdjustmentRule rule in adjustmentRules) {
 586                                 if (rule.DateStart > date.Date)
 587                                         return null;
 588                                 if (rule.DateEnd < date.Date)
 589                                         continue;
 590                                 return rule;
 591                         }
 592                         return null;
 593                 }
 594
 595                 private static DateTime TransitionPoint (TransitionTime transition, int year)
 596                 {
 597                         if (transition.IsFixedDateRule)
 598                                 return new DateTime (year, transition.Month, transition.Day) + transition.TimeOfDay.TimeOfDay;
 599
 600                         DayOfWeek first = (new DateTime (year, transition.Month, 1)).DayOfWeek;
 601                         int day = 1 + (transition.Week - 1) * 7 + (transition.DayOfWeek - first) % 7;
 602                         if (day >  DateTime.DaysInMonth (year, transition.Month))
 603                                 day -= 7;
 604                         return new DateTime (year, transition.Month, day) + transition.TimeOfDay.TimeOfDay;
 605                 }
 606
 607 #if LIBC
 608                 private static bool ValidTZFile (byte [] buffer, int length)
 609                 {
 610                         StringBuilder magic = new StringBuilder ();
 611
 612                         for (int i = 0; i < 4; i++)
 613                                 magic.Append ((char)buffer [i]);
 614
 615                         if (magic.ToString () != "TZif")
 616                                 return false;
 617
 618                         if (length >= BUFFER_SIZE)
 619                                 return false;
 620
 621                         return true;
 622                 }
 623
 624                 struct TimeType
 625                 {
 626                         public readonly int Offset;
 627                         public readonly bool IsDst;
 628                         public string Name;
 629
 630                         public TimeType (int offset, bool is_dst, string abbrev)
 631                         {
 632                                 this.Offset = offset;
 633                                 this.IsDst = is_dst;
 634                                 this.Name = abbrev;
 635                         }
 636
 637                         public override string ToString ()
 638                         {
 639                                 return "offset: " + Offset + "s, is_dst: " + IsDst + ", zone name: " + Name;
 640                         }
 641                 }
 642
 643                 private static TimeZoneInfo ParseTZBuffer (string id, byte [] buffer, int length)
 644                 {
 645                         DataConverter enc = DataConverter.BigEndian;
 646
 647                         //Reading the header. 4 bytes for magic, 16 are reserved
 648                         int ttisgmtcnt = enc.GetInt32 (buffer, 20);
 649                         int ttisstdcnt = enc.GetInt32 (buffer, 24);
 650                         int leapcnt = enc.GetInt32 (buffer, 28);
 651                         int timecnt = enc.GetInt32 (buffer, 32);
 652                         int typecnt = enc.GetInt32 (buffer, 36);
 653                         int charcnt = enc.GetInt32 (buffer, 40);
 654
 655                         if (length < 44 + timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt)
 656                                 throw new InvalidTimeZoneException ();
 657
 658                         Dictionary<int, string> abbreviations = ParseAbbreviations (buffer, 44 + 4 * timecnt + timecnt + 6 * typecnt, charcnt);
 659                         Dictionary<int, TimeType> time_types = ParseTimesTypes (buffer, 44 + 4 * timecnt + timecnt, typecnt, abbreviations);
 660                         SortedList<DateTime, TimeType> transitions = ParseTransitions (buffer, 44, timecnt, time_types);
 661
 662                         if (time_types.Count == 0)
 663                                 throw new InvalidTimeZoneException ();
 664
 665                         if (time_types.Count == 1 && ((TimeType)time_types[0]).IsDst)
 666                                 throw new InvalidTimeZoneException ();
 667
 668                         TimeSpan baseUtcOffset = new TimeSpan (0);
 669                         TimeSpan dstDelta = new TimeSpan (0);
 670                         string standardDisplayName = null;
 671                         string daylightDisplayName = null;
 672                         bool dst_observed = false;
 673                         DateTime dst_start = DateTime.MinValue;
 674                         List<AdjustmentRule> adjustmentRules = new List<AdjustmentRule> ();
 675
 676                         for (int i = 0; i < transitions.Count; i++) {
 677                                 DateTime ttime = transitions.Keys [i];
 678                                 TimeType ttype = transitions [ttime];
 679                                 if (!ttype.IsDst) {
 680                                         if (standardDisplayName != ttype.Name || baseUtcOffset.TotalSeconds != ttype.Offset) {
 681                                                 standardDisplayName = ttype.Name;
 682                                                 daylightDisplayName = null;
 683                                                 baseUtcOffset = new TimeSpan (0, 0, ttype.Offset);
 684                                                 adjustmentRules = new List<AdjustmentRule> ();
 685                                                 dst_observed = false;
 686                                         }
 687                                         if (dst_observed) {
 688                                                 //FIXME: check additional fields for this:
 689                                                 //most of the transitions are expressed in GMT
 690                                                 dst_start += baseUtcOffset;
 691                                                 DateTime dst_end = ttime + baseUtcOffset + dstDelta;
 692
 693                                                 //some weird timezone (America/Phoenix) have end dates on Jan 1st
 694                                                 if (dst_end.Date == new DateTime (dst_end.Year, 1, 1) && dst_end.Year > dst_start.Year)
 695                                                         dst_end -= new TimeSpan (24, 0, 0);
 696
 697                                                 DateTime dateStart, dateEnd;
 698                                                 if (dst_start.Month < 7)
 699                                                         dateStart = new DateTime (dst_start.Year, 1, 1);
 700                                                 else
 701                                                         dateStart = new DateTime (dst_start.Year, 7, 1);
 702
 703                                                 if (dst_end.Month >= 7)
 704                                                         dateEnd = new DateTime (dst_end.Year, 12, 31);
 705                                                 else
 706                                                         dateEnd = new DateTime (dst_end.Year, 6, 30);
 707
 708
 709                                                 TransitionTime transition_start = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_start.TimeOfDay, dst_start.Month, dst_start.Day);
 710                                                 TransitionTime transition_end = TransitionTime.CreateFixedDateRule (new DateTime (1, 1, 1) + dst_end.TimeOfDay, dst_end.Month, dst_end.Day);
 711                                                 adjustmentRules.Add (AdjustmentRule.CreateAdjustmentRule (dateStart, dateEnd, dstDelta, transition_start, transition_end));
 712                                         }
 713                                         dst_observed = false;
 714                                 } else {
 715                                         if (daylightDisplayName != ttype.Name || dstDelta.TotalSeconds != ttype.Offset - baseUtcOffset.TotalSeconds) {
 716                                                 daylightDisplayName = ttype.Name;
 717                                                 dstDelta = new TimeSpan(0, 0, ttype.Offset) - baseUtcOffset;
 718                                         }
 719                                         dst_start = ttime;
 720                                         dst_observed = true;
 721                                 }
 722                         }
 723
 724                         if (adjustmentRules.Count == 0) {
 725                                 TimeType t = (TimeType)time_types [0];
 726                                 if (standardDisplayName == null) {
 727                                         standardDisplayName = t.Name;
 728                                         baseUtcOffset = new TimeSpan (0, 0, t.Offset);
 729                                 }
 730                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName);
 731                         } else {
 732                                 return CreateCustomTimeZone (id, baseUtcOffset, id, standardDisplayName, daylightDisplayName, adjustmentRules.ToArray ());
 733                         }
 734                 }
 735
 736                 static Dictionary<int, string> ParseAbbreviations (byte [] buffer, int index, int count)
 737                 {
 738                         var abbrevs = new Dictionary<int, string> ();
 739                         int abbrev_index = 0;
 740                         var sb = new StringBuilder ();
 741                         for (int i = 0; i < count; i++) {
 742                                 char c = (char) buffer [index + i];
 743                                 if (c != '\0')
 744                                         sb.Append (c);
 745                                 else {
 746                                         abbrevs.Add (abbrev_index, sb.ToString ());
 747                                         abbrev_index = i + 1;
 748                                         sb = new StringBuilder ();
 749                                 }
 750                         }
 751                         return abbrevs;
 752                 }
 753
 754                 static Dictionary<int, TimeType> ParseTimesTypes (byte [] buffer, int index, int count, Dictionary<int, string> abbreviations)
 755                 {
 756                         DataConverter enc = DataConverter.BigEndian;
 757                         var types = new Dictionary<int, TimeType> (count);
 758                         for (int i = 0; i < count; i++) {
 759                                 int offset = enc.GetInt32 (buffer, index + 6 * i);
 760                                 byte is_dst = buffer [index + 6 * i + 4];
 761                                 byte abbrev = buffer [index + 6 * i + 5];
 762                                 types.Add (i, new TimeType (offset, (is_dst != 0), abbreviations [(int)abbrev]));
 763                         }
 764                         return types;
 765                 }
 766
 767                 static SortedList<DateTime, TimeType> ParseTransitions (byte [] buffer, int index, int count, Dictionary<int, TimeType> time_types)
 768                 {
 769                         DataConverter enc = DataConverter.BigEndian;
 770                         var trans = new SortedList<DateTime, TimeType> (count);
 771                         for (int i = 0; i < count; i++) {
 772                                 int unixtime = enc.GetInt32 (buffer, index + 4 * i);
 773                                 DateTime ttime = DateTimeFromUnixTime (unixtime);
 774                                 byte ttype = buffer [index + 4 * count + i];
 775                                 trans.Add (ttime, time_types [(int)ttype]);
 776                         }
 777                         return trans;
 778                 }
 779
 780                 static DateTime DateTimeFromUnixTime (long unix_time)
 781                 {
 782                         DateTime date_time = new DateTime (1970, 1, 1);
 783                         return date_time.AddSeconds (unix_time);
 784                 }
 785 #endif
 786         }
 787 }