mcs/class/corlib/System/Environment.cs

   1 //------------------------------------------------------------------------------
   2 //
   3 // System.Environment.cs
   4 //
   5 // Copyright (C) 2001 Moonlight Enterprises, All Rights Reserved
   6 //
   7 // Author:         Jim Richardson, develop@wtfo-guru.com
   8 //                 Dan Lewis (dihlewis@yahoo.co.uk)
   9 // Created:        Saturday, August 11, 2001
  10 //
  11 //------------------------------------------------------------------------------
  12 //
  13 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System.IO;
  36 using System.Collections;
  37 using System.Runtime.CompilerServices;
  38 using System.Security;
  39 using System.Security.Permissions;
  40 using System.Text;
  41 using System.Runtime.InteropServices;
  42
  43 namespace System {
  44
  45 #if NET_2_0
  46         [ComVisible (true)]
  47 #endif
  48 #if NET_2_0
  49         public static class Environment {
  50 #else
  51         public sealed class Environment {
  52
  53                 private Environment ()
  54                 {
  55                 }
  56 #endif
  57                 /*
  58                  * This is the version number of the corlib-runtime interface. When
  59                  * making changes to this interface (by changing the layout
  60                  * of classes the runtime knows about, changing icall signature or
  61                  * semantics etc), increment this variable. Also increment the
  62                  * pair of this variable in the runtime in metadata/appdomain.c.
  63                  * Changes which are already detected at runtime, like the addition
  64                  * of icalls, do not require an increment.
  65                  */
  66                 private const int mono_corlib_version = 69;
  67
  68 #if NET_2_0
  69                 [ComVisible (true)]
  70 #endif
  71                 public enum SpecialFolder
  72                 {       // TODO: Determine if these windoze style folder identifiers
  73                         //       have unix/linux counterparts
  74 #if NET_2_0
  75                         MyDocuments = 0x05,
  76 #endif
  77 #if NET_1_1
  78                         Desktop = 0x00,
  79                         MyComputer = 0x11,
  80 #endif
  81                         Programs = 0x02,
  82                         Personal = 0x05,
  83                         Favorites = 0x06,
  84                         Startup = 0x07,
  85                         Recent = 0x08,
  86                         SendTo = 0x09,
  87                         StartMenu = 0x0b,
  88                         MyMusic = 0x0d,
  89                         DesktopDirectory = 0x10,
  90                         Templates = 0x15,
  91                         ApplicationData = 0x1a,
  92                         LocalApplicationData = 0x1c,
  93                         InternetCache = 0x20,
  94                         Cookies = 0x21,
  95                         History = 0x22,
  96                         CommonApplicationData   = 0x23,
  97                         System = 0x25,
  98                         ProgramFiles = 0x26,
  99                         MyPictures = 0x27,
 100                         CommonProgramFiles = 0x2b,
 101                 }
 102
 103                 /// <summary>
 104                 /// Gets the command line for this process
 105                 /// </summary>
 106                 public static string CommandLine {
 107                         // note: security demand inherited from calling GetCommandLineArgs
 108                         get {
 109                                 // FIXME: we may need to quote, but any sane person
 110                                 // should use GetCommandLineArgs () instead.
 111                                 return String.Join (" ", GetCommandLineArgs ());
 112                         }
 113                 }
 114
 115                 /// <summary>
 116                 /// Gets or sets the current directory. Actually this is supposed to get
 117                 /// and/or set the process start directory acording to the documentation
 118                 /// but actually test revealed at beta2 it is just Getting/Setting the CurrentDirectory
 119                 /// </summary>
 120                 public static string CurrentDirectory
 121                 {
 122                         get {
 123                                 return Directory.GetCurrentDirectory ();
 124                         }
 125                         set {
 126                                 Directory.SetCurrentDirectory (value);
 127                         }
 128                 }
 129
 130                 /// <summary>
 131                 /// Gets or sets the exit code of this process
 132                 /// </summary>
 133                 public extern static int ExitCode
 134                 {
 135                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 136                         get;
 137                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 138                         set;
 139                 }
 140
 141 #if NET_1_1
 142                 static
 143 #endif
 144                 public extern bool HasShutdownStarted
 145                 {
 146                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 147                         get;
 148                 }
 149
 150
 151                 /// <summary>
 152                 /// Gets the name of the local computer
 153                 /// </summary>
 154                 public extern static string MachineName {
 155                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 156                         [EnvironmentPermission (SecurityAction.Demand, Read="COMPUTERNAME")]
 157                         [SecurityPermission (SecurityAction.Demand, UnmanagedCode=true)]
 158                         get;
 159                 }
 160
 161                 /// <summary>
 162                 /// Gets the standard new line value
 163                 /// </summary>
 164                 public extern static string NewLine {
 165                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 166                         get;
 167                 }
 168
 169                 //
 170                 // Support methods and fields for OSVersion property
 171                 //
 172                 static OperatingSystem os;
 173
 174                 internal static extern PlatformID Platform {
 175                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 176                         get;
 177                 }
 178
 179                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 180                 internal static extern string GetOSVersionString ();
 181
 182                 /// <summary>
 183                 /// Gets the current OS version information
 184                 /// </summary>
 185                 public static OperatingSystem OSVersion {
 186                         get {
 187                                 if (os == null) {
 188                                         Version v = Version.CreateFromString (GetOSVersionString ());
 189                                         PlatformID p = Platform;
 190 #if NET_2_0
 191                                         if ((int) p == 128)
 192                                                 p = PlatformID.Unix;
 193 #endif
 194                                         os = new OperatingSystem (p, v);
 195                                 }
 196                                 return os;
 197                         }
 198                 }
 199
 200                 /// <summary>
 201                 /// Get StackTrace
 202                 /// </summary>
 203                 public static string StackTrace {
 204                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 205                         get {
 206                                 System.Diagnostics.StackTrace trace = new System.Diagnostics.StackTrace (0, true);
 207                                 return trace.ToString ();
 208                         }
 209                 }
 210
 211                 /// <summary>
 212                 /// Get a fully qualified path to the system directory
 213                 /// </summary>
 214                 public static string SystemDirectory {
 215                         get {
 216                                 return GetFolderPath (SpecialFolder.System);
 217                         }
 218                 }
 219
 220                 /// <summary>
 221                 /// Get the number of milliseconds that have elapsed since the system was booted
 222                 /// </summary>
 223                 public extern static int TickCount {
 224                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 225                         get;
 226                 }
 227
 228                 /// <summary>
 229                 /// Get UserDomainName
 230                 /// </summary>
 231                 public static string UserDomainName {
 232                         // FIXME: this variable doesn't exist (at least not on WinXP) - reported to MS as FDBK20562
 233                         [EnvironmentPermission (SecurityAction.Demand, Read="USERDOMAINNAME")]
 234                         get {
 235                                 return MachineName;
 236                         }
 237                 }
 238
 239                 /// <summary>
 240                 /// Gets a flag indicating whether the process is in interactive mode
 241                 /// </summary>
 242                 [MonoTODO ("Currently always returns false, regardless of interactive state")]
 243                 public static bool UserInteractive {
 244                         get {
 245                                 return false;
 246                         }
 247                 }
 248
 249                 /// <summary>
 250                 /// Get the user name of current process is running under
 251                 /// </summary>
 252                 public extern static string UserName {
 253                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 254                         [EnvironmentPermission (SecurityAction.Demand, Read="USERNAME;USER")]
 255                         get;
 256                 }
 257
 258                 /// <summary>
 259                 /// Get the version of the common language runtime
 260                 /// </summary>
 261                 public static Version Version {
 262                         get {
 263                                 return new Version (Consts.FxFileVersion);
 264                         }
 265                 }
 266
 267                 /// <summary>
 268                 /// Get the amount of physical memory mapped to process
 269                 /// </summary>
 270                 [MonoTODO ("Currently always returns zero")]
 271                 public static long WorkingSet {
 272                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 273                         get { return 0; }
 274                 }
 275
 276                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 277                 [SecurityPermission (SecurityAction.Demand, UnmanagedCode=true)]
 278                 public extern static void Exit (int exitCode);
 279
 280                 /// <summary>
 281                 /// Substitute environment variables in the argument "name"
 282                 /// </summary>
 283                 public static string ExpandEnvironmentVariables (string name)
 284                 {
 285                         if (name == null)
 286                                 throw new ArgumentNullException ("name");
 287
 288                         int off1 = name.IndexOf ('%');
 289                         if (off1 == -1)
 290                                 return name;
 291
 292                         int len = name.Length;
 293                         int off2 = 0;
 294                         if (off1 == len - 1 || (off2 = name.IndexOf ('%', off1 + 1)) == -1)
 295                                 return name;
 296
 297                         StringBuilder result = new StringBuilder ();
 298                         result.Append (name, 0, off1);
 299                         Hashtable tbl = null;
 300                         do {
 301                                 string var = name.Substring (off1 + 1, off2 - off1 - 1);
 302                                 string value = GetEnvironmentVariable (var);
 303                                 if (value == null && Environment.IsRunningOnWindows) {
 304                                         // On windows, env. vars. are case insensitive
 305                                         if (tbl == null)
 306                                                 tbl = GetEnvironmentVariablesNoCase ();
 307
 308                                         value = tbl [var] as string;
 309                                 }
 310
 311                                 // If value not found, add %FOO to stream,
 312                                 //  and use the closing % for the next iteration.
 313                                 // If value found, expand it in place of %FOO%
 314                                 if (value == null) {
 315                                         result.Append ('%');
 316                                         result.Append (var);
 317                                         off2--;
 318                                 } else {
 319                                         result.Append (value);
 320                                 }
 321                                 int oldOff2 = off2;
 322                                 off1 = name.IndexOf ('%', off2 + 1);
 323                                 // If no % found for off1, don't look for one for off2
 324                                 off2 = (off1 == -1 || off2 > len-1)? -1 :name.IndexOf ('%', off1 + 1);
 325                                 // textLen is the length of text between the closing % of current iteration
 326                                 //  and the starting % of the next iteration if any. This text is added to output
 327                                 int textLen;
 328                                 // If no new % found, use all the remaining text
 329                                 if (off1 == -1 || off2 == -1)
 330                                         textLen = len - oldOff2 - 1;
 331                                 // If value found in current iteration, use text after current closing % and next %
 332                                 else if(value != null)
 333                                         textLen = off1 - oldOff2 - 1;
 334                                 // If value not found in current iteration, but a % was found for next iteration,
 335                                 //  use text from current closing % to the next %.
 336                                 else
 337                                         textLen = off1 - oldOff2;
 338                                 if(off1 >= oldOff2 || off1 == -1)
 339                                         result.Append (name, oldOff2+1, textLen);
 340                         } while (off2 > -1 && off2 < len);
 341
 342                         return result.ToString ();
 343
 344                 }
 345
 346                 /// <summary>
 347                 /// Return an array of the command line arguments of the current process
 348                 /// </summary>
 349                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 350                 [EnvironmentPermissionAttribute (SecurityAction.Demand, Read = "PATH")]
 351                 public extern static string[] GetCommandLineArgs ();
 352
 353                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 354                 internal extern static string internalGetEnvironmentVariable (string variable);
 355
 356                 /// <summary>
 357                 /// Return a string containing the value of the environment
 358                 /// variable identifed by parameter "variable"
 359                 /// </summary>
 360                 public static string GetEnvironmentVariable (string variable)
 361                 {
 362                         if (SecurityManager.SecurityEnabled) {
 363                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, variable).Demand ();
 364                         }
 365                         return internalGetEnvironmentVariable (variable);
 366                 }
 367
 368                 static Hashtable GetEnvironmentVariablesNoCase ()
 369                 {
 370                         Hashtable vars = new Hashtable (CaseInsensitiveHashCodeProvider.Default,
 371                                                         CaseInsensitiveComparer.Default);
 372
 373                         foreach (string name in GetEnvironmentVariableNames ()) {
 374                                 vars [name] = internalGetEnvironmentVariable (name);
 375                         }
 376
 377                         return vars;
 378                 }
 379
 380                 /// <summary>
 381                 /// Return a set of all environment variables and their values
 382                 /// </summary>
 383 #if NET_2_0
 384                 public static IDictionary GetEnvironmentVariables ()
 385                 {
 386                         StringBuilder sb = null;
 387                         if (SecurityManager.SecurityEnabled) {
 388                                 // we must have access to each variable to get the lot
 389                                 sb = new StringBuilder ();
 390                                 // but (performance-wise) we do not want a stack-walk
 391                                 // for each of them so we concatenate them
 392                         }
 393
 394                         Hashtable vars = new Hashtable ();
 395                         foreach (string name in GetEnvironmentVariableNames ()) {
 396                                 vars [name] = internalGetEnvironmentVariable (name);
 397                                 if (sb != null) {
 398                                         sb.Append (name);
 399                                         sb.Append (";");
 400                                 }
 401                         }
 402
 403                         if (sb != null) {
 404                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, sb.ToString ()).Demand ();
 405                         }
 406                         return vars;
 407                 }
 408 #else
 409                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 410                 public static IDictionary GetEnvironmentVariables ()
 411                 {
 412                         Hashtable vars = new Hashtable ();
 413                         foreach (string name in GetEnvironmentVariableNames ()) {
 414                                 vars [name] = internalGetEnvironmentVariable (name);
 415                         }
 416                         return vars;
 417                 }
 418 #endif
 419
 420                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 421                 private extern static string GetWindowsFolderPath (int folder);
 422
 423                 /// <summary>
 424                 /// Returns the fully qualified path of the
 425                 /// folder specified by the "folder" parameter
 426                 /// </summary>
 427                 public static string GetFolderPath (SpecialFolder folder)
 428                 {
 429                         string dir = null;
 430
 431                         if (Environment.IsRunningOnWindows) {
 432                                 dir = GetWindowsFolderPath ((int) folder);
 433                         } else {
 434                                 dir = InternalGetFolderPath (folder);
 435                         }
 436
 437                         if ((dir != null) && (dir.Length > 0) && SecurityManager.SecurityEnabled) {
 438                                 new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dir).Demand ();
 439                         }
 440                         return dir;
 441                 }
 442
 443                 private static string ReadXdgUserDir (string config_dir, string home_dir,
 444                         string key, string fallback)
 445                 {
 446                         string env_path = internalGetEnvironmentVariable (key);
 447                         if (env_path != null && env_path != String.Empty) {
 448                                 return env_path;
 449                         }
 450
 451                         string user_dirs_path = Path.Combine (config_dir, "user-dirs.dirs");
 452
 453                         if (!File.Exists (user_dirs_path)) {
 454                                 return Path.Combine (home_dir, fallback);
 455                         }
 456
 457                         try {
 458                                 using(StreamReader reader = new StreamReader (user_dirs_path)) {
 459                                         string line;
 460                                         while ((line = reader.ReadLine ()) != null) {
 461                                                 line = line.Trim ();
 462                                                 int delim_index = line.IndexOf ('=');
 463                         if(delim_index > 8 && line.Substring (0, delim_index) == key) {
 464                             string path = line.Substring (delim_index + 1).Trim ('"');
 465                             bool relative = false;
 466
 467                             if (path.StartsWith ("$HOME/")) {
 468                                 relative = true;
 469                                 path = path.Substring (6);
 470                             } else if (!path.StartsWith ("/")) {
 471                                 relative = true;
 472                             }
 473
 474                             return relative ? Path.Combine (home_dir, path) : path;
 475                         }
 476                                         }
 477                                 }
 478                         } catch (FileNotFoundException) {
 479                         }
 480
 481                         return Path.Combine (home_dir, fallback);
 482                 }
 483
 484
 485                 // the security runtime (and maybe other parts of corlib) needs the
 486                 // information to initialize themselves before permissions can be checked
 487                 internal static string InternalGetFolderPath (SpecialFolder folder)
 488                 {
 489                         string home = internalGetHome ();
 490
 491                         // http://freedesktop.org/Standards/basedir-spec/basedir-spec-0.6.html
 492
 493                         // note: skip security check for environment variables
 494                         string data = internalGetEnvironmentVariable ("XDG_DATA_HOME");
 495                         if ((data == null) || (data == String.Empty)) {
 496                                 data = Path.Combine (home, ".local");
 497                                 data = Path.Combine (data, "share");
 498                         }
 499
 500                         // note: skip security check for environment variables
 501                         string config = internalGetEnvironmentVariable ("XDG_CONFIG_HOME");
 502                         if ((config == null) || (config == String.Empty)) {
 503                                 config = Path.Combine (home, ".config");
 504                         }
 505
 506                         switch (folder) {
 507 #if NET_1_1
 508                         // MyComputer is a virtual directory
 509                         case SpecialFolder.MyComputer:
 510                                 return String.Empty;
 511 #endif
 512                         // personal == ~
 513                         case SpecialFolder.Personal:
 514                                 return home;
 515                         // use FDO's CONFIG_HOME. This data will be synced across a network like the windows counterpart.
 516                         case SpecialFolder.ApplicationData:
 517                                 return config;
 518                         //use FDO's DATA_HOME. This is *NOT* synced
 519                         case SpecialFolder.LocalApplicationData:
 520                                 return data;
 521 #if NET_1_1
 522                         case SpecialFolder.Desktop:
 523 #endif
 524                         case SpecialFolder.DesktopDirectory:
 525                                 return ReadXdgUserDir (config, home, "XDG_DESKTOP_DIR", "Desktop");
 526
 527                         case SpecialFolder.MyMusic:
 528                                 return ReadXdgUserDir (config, home, "XDG_MUSIC_DIR", "Music");
 529
 530                         case SpecialFolder.MyPictures:
 531                                 return ReadXdgUserDir (config, home, "XDG_PICTURES_DIR", "Pictures");
 532
 533                         // these simply dont exist on Linux
 534                         // The spec says if a folder doesnt exist, we
 535                         // should return ""
 536                         case SpecialFolder.Favorites:
 537                         case SpecialFolder.Programs:
 538                         case SpecialFolder.SendTo:
 539                         case SpecialFolder.StartMenu:
 540                         case SpecialFolder.Startup:
 541                         case SpecialFolder.Templates:
 542                         case SpecialFolder.Cookies:
 543                         case SpecialFolder.History:
 544                         case SpecialFolder.InternetCache:
 545                         case SpecialFolder.Recent:
 546                         case SpecialFolder.CommonProgramFiles:
 547                         case SpecialFolder.ProgramFiles:
 548                         case SpecialFolder.System:
 549                                 return String.Empty;
 550                         // This is where data common to all users goes
 551                         case SpecialFolder.CommonApplicationData:
 552                                 return "/usr/share";
 553                         default:
 554                                 throw new ArgumentException ("Invalid SpecialFolder");
 555                         }
 556                 }
 557
 558                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 559                 public static string[] GetLogicalDrives ()
 560                 {
 561                         return GetLogicalDrivesInternal ();
 562                 }
 563
 564 #if NET_2_0
 565                 public static string GetEnvironmentVariable (string variable, EnvironmentVariableTarget target)
 566                 {
 567                         switch (target) {
 568                         case EnvironmentVariableTarget.Process:
 569                                 return GetEnvironmentVariable (variable);
 570                         case EnvironmentVariableTarget.Machine:
 571                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 572                                 if (!IsRunningOnWindows)
 573                                         return null;
 574                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment")) {
 575                                         return env.GetValue (variable).ToString ();
 576                                 }
 577                         case EnvironmentVariableTarget.User:
 578                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 579                                 if (!IsRunningOnWindows)
 580                                         return null;
 581                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment", false)) {
 582                                         return env.GetValue (variable).ToString ();
 583                                 }
 584                         default:
 585                                 throw new ArgumentException ("target");
 586                         }
 587                 }
 588
 589                 public static IDictionary GetEnvironmentVariables (EnvironmentVariableTarget target)
 590                 {
 591                         IDictionary variables = (IDictionary)new Hashtable ();
 592                         switch (target) {
 593                         case EnvironmentVariableTarget.Process:
 594                                 variables = GetEnvironmentVariables ();
 595                                 break;
 596                         case EnvironmentVariableTarget.Machine:
 597                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 598                                 if (IsRunningOnWindows) {
 599                                         using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment")) {
 600                                                 string[] value_names = env.GetValueNames ();
 601                                                 foreach (string value_name in value_names)
 602                                                         variables.Add (value_name, env.GetValue (value_name));
 603                                         }
 604                                 }
 605                                 break;
 606                         case EnvironmentVariableTarget.User:
 607                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 608                                 if (IsRunningOnWindows) {
 609                                         using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment")) {
 610                                                 string[] value_names = env.GetValueNames ();
 611                                                 foreach (string value_name in value_names)
 612                                                         variables.Add (value_name, env.GetValue (value_name));
 613                                         }
 614                                 }
 615                                 break;
 616                         default:
 617                                 throw new ArgumentException ("target");
 618                         }
 619                         return variables;
 620                 }
 621
 622                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 623                 public static void SetEnvironmentVariable (string variable, string value)
 624                 {
 625                         SetEnvironmentVariable (variable, value, EnvironmentVariableTarget.Process);
 626                 }
 627
 628                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted = true)]
 629                 public static void SetEnvironmentVariable (string variable, string value, EnvironmentVariableTarget target)
 630                 {
 631                         if (variable == null)
 632                                 throw new ArgumentNullException ("variable");
 633                         if (variable == String.Empty)
 634                                 throw new ArgumentException ("String cannot be of zero length.", "variable");
 635                         if (variable.IndexOf ('=') != -1)
 636                                 throw new ArgumentException ("Environment variable name cannot contain an equal character.", "variable");
 637                         if (variable[0] == '\0')
 638                                 throw new ArgumentException ("The first char in the string is the null character.", "variable");
 639
 640                         switch (target) {
 641                         case EnvironmentVariableTarget.Process:
 642                                 InternalSetEnvironmentVariable (variable, value);
 643                                 break;
 644                         case EnvironmentVariableTarget.Machine:
 645                                 if (!IsRunningOnWindows)
 646                                         return;
 647                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment", true)) {
 648                                         if (String.IsNullOrEmpty (value))
 649                                                 env.DeleteValue (variable, false);
 650                                         else
 651                                                 env.SetValue (variable, value);
 652                                 }
 653                                 break;
 654                         case EnvironmentVariableTarget.User:
 655                                 if (!IsRunningOnWindows)
 656                                         return;
 657                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment", true)) {
 658                                         if (String.IsNullOrEmpty (value))
 659                                                 env.DeleteValue (variable, false);
 660                                         else
 661                                                 env.SetValue (variable, value);
 662                                 }
 663                                 break;
 664                         default:
 665                                 throw new ArgumentException ("target");
 666                         }
 667                 }
 668
 669                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 670                 internal static extern void InternalSetEnvironmentVariable (string variable, string value);
 671
 672                 public static extern int ProcessorCount {
 673                         [EnvironmentPermission (SecurityAction.Demand, Read="NUMBER_OF_PROCESSORS")]
 674                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 675                         get;
 676                 }
 677
 678                 [MonoTODO ("Not implemented")]
 679                 [SecurityPermission (SecurityAction.LinkDemand, UnmanagedCode=true)]
 680                 public static void FailFast (string message)
 681                 {
 682                         throw new NotImplementedException ();
 683                 }
 684 #endif
 685
 686                 // private methods
 687
 688                 internal static bool IsRunningOnWindows {
 689                         get { return ((int) Platform != 128); }
 690                 }
 691
 692                 private static string GacPath {
 693                         get {
 694                                 if (Environment.IsRunningOnWindows) {
 695                                         /* On windows, we don't know the path where mscorlib.dll will be installed */
 696                                         string corlibDir = new DirectoryInfo (Path.GetDirectoryName (typeof (int).Assembly.Location)).Parent.Parent.FullName;
 697                                         return Path.Combine (Path.Combine (corlibDir, "mono"), "gac");
 698                                 }
 699
 700                                 return Path.Combine (Path.Combine (internalGetGacPath (), "mono"), "gac");
 701                         }
 702                 }
 703
 704                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 705                 private extern static string [] GetLogicalDrivesInternal ();
 706
 707                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 708                 private extern static string [] GetEnvironmentVariableNames ();
 709
 710                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 711                 internal extern static string GetMachineConfigPath ();
 712
 713                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 714                 internal extern static string internalGetGacPath ();
 715
 716                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 717                 internal extern static string internalGetHome ();
 718         }
 719 }
 720