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 = 58;
  67
  68                 public enum SpecialFolder
  69                 {       // TODO: Determine if these windoze style folder identifiers
  70                         //       have unix/linux counterparts
  71 #if NET_2_0
  72                         MyDocuments = 0x05,
  73 #endif
  74 #if NET_1_1
  75                         Desktop = 0x00,
  76                         MyComputer = 0x11,
  77 #endif
  78                         Programs = 0x02,
  79                         Personal = 0x05,
  80                         Favorites = 0x06,
  81                         Startup = 0x07,
  82                         Recent = 0x08,
  83                         SendTo = 0x09,
  84                         StartMenu = 0x0b,
  85                         MyMusic = 0x0d,
  86                         DesktopDirectory = 0x10,
  87                         Templates = 0x15,
  88                         ApplicationData = 0x1a,
  89                         LocalApplicationData = 0x1c,
  90                         InternetCache = 0x20,
  91                         Cookies = 0x21,
  92                         History = 0x22,
  93                         CommonApplicationData   = 0x23,
  94                         System = 0x25,
  95                         ProgramFiles = 0x26,
  96                         MyPictures = 0x27,
  97                         CommonProgramFiles = 0x2b,
  98                 }
  99
 100                 /// <summary>
 101                 /// Gets the command line for this process
 102                 /// </summary>
 103                 public static string CommandLine {
 104                         // note: security demand inherited from calling GetCommandLineArgs
 105                         get {
 106                                 // FIXME: we may need to quote, but any sane person
 107                                 // should use GetCommandLineArgs () instead.
 108                                 return String.Join (" ", GetCommandLineArgs ());
 109                         }
 110                 }
 111
 112                 /// <summary>
 113                 /// Gets or sets the current directory. Actually this is supposed to get
 114                 /// and/or set the process start directory acording to the documentation
 115                 /// but actually test revealed at beta2 it is just Getting/Setting the CurrentDirectory
 116                 /// </summary>
 117                 public static string CurrentDirectory
 118                 {
 119                         get {
 120                                 return Directory.GetCurrentDirectory ();
 121                         }
 122                         set {
 123                                 Directory.SetCurrentDirectory (value);
 124                         }
 125                 }
 126
 127                 /// <summary>
 128                 /// Gets or sets the exit code of this process
 129                 /// </summary>
 130                 public extern static int ExitCode
 131                 {
 132                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 133                         get;
 134                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 135                         set;
 136                 }
 137
 138 #if NET_1_1
 139                 static
 140 #endif
 141                 public extern bool HasShutdownStarted
 142                 {
 143                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 144                         get;
 145                 }
 146
 147
 148                 /// <summary>
 149                 /// Gets the name of the local computer
 150                 /// </summary>
 151                 public extern static string MachineName {
 152                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 153                         [EnvironmentPermission (SecurityAction.Demand, Read="COMPUTERNAME")]
 154                         [SecurityPermission (SecurityAction.Demand, UnmanagedCode=true)]
 155                         get;
 156                 }
 157
 158                 /// <summary>
 159                 /// Gets the standard new line value
 160                 /// </summary>
 161                 public extern static string NewLine {
 162                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 163                         get;
 164                 }
 165
 166                 //
 167                 // Support methods and fields for OSVersion property
 168                 //
 169                 static OperatingSystem os;
 170
 171                 internal static extern PlatformID Platform {
 172                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 173                         get;
 174                 }
 175
 176                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 177                 internal static extern string GetOSVersionString ();
 178
 179                 /// <summary>
 180                 /// Gets the current OS version information
 181                 /// </summary>
 182                 public static OperatingSystem OSVersion {
 183                         get {
 184                                 if (os == null) {
 185                                         Version v = Version.CreateFromString (GetOSVersionString ());
 186                                         PlatformID p = Platform;
 187 #if NET_2_0
 188                                         if ((int) p == 128)
 189                                                 p = PlatformID.Unix;
 190 #endif
 191                                         os = new OperatingSystem (p, v);
 192                                 }
 193                                 return os;
 194                         }
 195                 }
 196
 197                 /// <summary>
 198                 /// Get StackTrace
 199                 /// </summary>
 200                 public static string StackTrace {
 201                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 202                         get {
 203                                 System.Diagnostics.StackTrace trace = new System.Diagnostics.StackTrace (0, true);
 204                                 return trace.ToString ();
 205                         }
 206                 }
 207
 208                 /// <summary>
 209                 /// Get a fully qualified path to the system directory
 210                 /// </summary>
 211                 public static string SystemDirectory {
 212                         get {
 213                                 return GetFolderPath (SpecialFolder.System);
 214                         }
 215                 }
 216
 217                 /// <summary>
 218                 /// Get the number of milliseconds that have elapsed since the system was booted
 219                 /// </summary>
 220                 public extern static int TickCount {
 221                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 222                         get;
 223                 }
 224
 225                 /// <summary>
 226                 /// Get UserDomainName
 227                 /// </summary>
 228                 public static string UserDomainName {
 229                         // FIXME: this variable doesn't exist (at least not on WinXP) - reported to MS as FDBK20562
 230                         [EnvironmentPermission (SecurityAction.Demand, Read="USERDOMAINNAME")]
 231                         get {
 232                                 return MachineName;
 233                         }
 234                 }
 235
 236                 /// <summary>
 237                 /// Gets a flag indicating whether the process is in interactive mode
 238                 /// </summary>
 239                 [MonoTODO ("Currently always returns false, regardless of interactive state")]
 240                 public static bool UserInteractive {
 241                         get {
 242                                 return false;
 243                         }
 244                 }
 245
 246                 /// <summary>
 247                 /// Get the user name of current process is running under
 248                 /// </summary>
 249                 public extern static string UserName {
 250                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 251                         [EnvironmentPermission (SecurityAction.Demand, Read="USERNAME;USER")]
 252                         get;
 253                 }
 254
 255                 /// <summary>
 256                 /// Get the version of the common language runtime
 257                 /// </summary>
 258                 public static Version Version {
 259                         get {
 260                                 return new Version (Consts.FxFileVersion);
 261                         }
 262                 }
 263
 264                 /// <summary>
 265                 /// Get the amount of physical memory mapped to process
 266                 /// </summary>
 267                 [MonoTODO ("Currently always returns zero")]
 268                 public static long WorkingSet {
 269                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 270                         get { return 0; }
 271                 }
 272
 273                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 274                 [SecurityPermission (SecurityAction.Demand, UnmanagedCode=true)]
 275                 public extern static void Exit (int exitCode);
 276
 277                 /// <summary>
 278                 /// Substitute environment variables in the argument "name"
 279                 /// </summary>
 280                 public static string ExpandEnvironmentVariables (string name)
 281                 {
 282                         if (name == null)
 283                                 throw new ArgumentNullException ("name");
 284
 285                         int off1 = name.IndexOf ('%');
 286                         if (off1 == -1)
 287                                 return name;
 288
 289                         int len = name.Length;
 290                         int off2 = 0;
 291                         if (off1 == len - 1 || (off2 = name.IndexOf ('%', off1 + 1)) == -1)
 292                                 return name;
 293
 294                         StringBuilder result = new StringBuilder ();
 295                         result.Append (name, 0, off1);
 296                         Hashtable tbl = null;
 297                         do {
 298                                 string var = name.Substring (off1 + 1, off2 - off1 - 1);
 299                                 string value = GetEnvironmentVariable (var);
 300                                 if (value == null && Environment.IsRunningOnWindows) {
 301                                         // On windows, env. vars. are case insensitive
 302                                         if (tbl == null)
 303                                                 tbl = GetEnvironmentVariablesNoCase ();
 304
 305                                         value = tbl [var] as string;
 306                                 }
 307
 308                                 // If value not found, add %FOO to stream,
 309                                 //  and use the closing % for the next iteration.
 310                                 // If value found, expand it in place of %FOO%
 311                                 if (value == null) {
 312                                         result.Append ('%');
 313                                         result.Append (var);
 314                                         off2--;
 315                                 } else {
 316                                         result.Append (value);
 317                                 }
 318                                 int oldOff2 = off2;
 319                                 off1 = name.IndexOf ('%', off2 + 1);
 320                                 // If no % found for off1, don't look for one for off2
 321                                 off2 = (off1 == -1 || off2 > len-1)? -1 :name.IndexOf ('%', off1 + 1);
 322                                 // textLen is the length of text between the closing % of current iteration
 323                                 //  and the starting % of the next iteration if any. This text is added to output
 324                                 int textLen;
 325                                 // If no new % found, use all the remaining text
 326                                 if (off1 == -1 || off2 == -1)
 327                                         textLen = len - oldOff2 - 1;
 328                                 // If value found in current iteration, use text after current closing % and next %
 329                                 else if(value != null)
 330                                         textLen = off1 - oldOff2 - 1;
 331                                 // If value not found in current iteration, but a % was found for next iteration,
 332                                 //  use text from current closing % to the next %.
 333                                 else
 334                                         textLen = off1 - oldOff2;
 335                                 if(off1 >= oldOff2 || off1 == -1)
 336                                         result.Append (name, oldOff2+1, textLen);
 337                         } while (off2 > -1 && off2 < len);
 338
 339                         return result.ToString ();
 340
 341                 }
 342
 343                 /// <summary>
 344                 /// Return an array of the command line arguments of the current process
 345                 /// </summary>
 346                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 347                 [EnvironmentPermissionAttribute (SecurityAction.Demand, Read = "PATH")]
 348                 public extern static string[] GetCommandLineArgs ();
 349
 350                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 351                 internal extern static string internalGetEnvironmentVariable (string name);
 352
 353                 /// <summary>
 354                 /// Return a string containing the value of the environment
 355                 /// variable identifed by parameter "variable"
 356                 /// </summary>
 357                 public static string GetEnvironmentVariable (string name)
 358                 {
 359                         if (SecurityManager.SecurityEnabled) {
 360                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, name).Demand ();
 361                         }
 362                         return internalGetEnvironmentVariable (name);
 363                 }
 364
 365                 static Hashtable GetEnvironmentVariablesNoCase ()
 366                 {
 367                         Hashtable vars = new Hashtable (CaseInsensitiveHashCodeProvider.Default,
 368                                                         CaseInsensitiveComparer.Default);
 369
 370                         foreach (string name in GetEnvironmentVariableNames ()) {
 371                                 vars [name] = internalGetEnvironmentVariable (name);
 372                         }
 373
 374                         return vars;
 375                 }
 376
 377                 /// <summary>
 378                 /// Return a set of all environment variables and their values
 379                 /// </summary>
 380 #if NET_2_0
 381                 public static IDictionary GetEnvironmentVariables ()
 382                 {
 383                         StringBuilder sb = null;
 384                         if (SecurityManager.SecurityEnabled) {
 385                                 // we must have access to each variable to get the lot
 386                                 sb = new StringBuilder ();
 387                                 // but (performance-wise) we do not want a stack-walk
 388                                 // for each of them so we concatenate them
 389                         }
 390
 391                         Hashtable vars = new Hashtable ();
 392                         foreach (string name in GetEnvironmentVariableNames ()) {
 393                                 vars [name] = internalGetEnvironmentVariable (name);
 394                                 if (sb != null) {
 395                                         sb.Append (name);
 396                                         sb.Append (";");
 397                                 }
 398                         }
 399
 400                         if (sb != null) {
 401                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, sb.ToString ()).Demand ();
 402                         }
 403                         return vars;
 404                 }
 405 #else
 406                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 407                 public static IDictionary GetEnvironmentVariables ()
 408                 {
 409                         Hashtable vars = new Hashtable ();
 410                         foreach (string name in GetEnvironmentVariableNames ()) {
 411                                 vars [name] = internalGetEnvironmentVariable (name);
 412                         }
 413                         return vars;
 414                 }
 415 #endif
 416
 417                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 418                 private extern static string GetWindowsFolderPath (int folder);
 419
 420                 /// <summary>
 421                 /// Returns the fully qualified path of the
 422                 /// folder specified by the "folder" parameter
 423                 /// </summary>
 424                 public static string GetFolderPath (SpecialFolder folder)
 425                 {
 426                         string dir = null;
 427
 428                         if (Environment.IsRunningOnWindows) {
 429                                 dir = GetWindowsFolderPath ((int) folder);
 430                         } else {
 431                                 dir = InternalGetFolderPath (folder);
 432                         }
 433
 434                         if ((dir != null) && (dir.Length > 0) && SecurityManager.SecurityEnabled) {
 435                                 new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dir).Demand ();
 436                         }
 437                         return dir;
 438                 }
 439
 440                 private static string ReadXdgUserDir (string config_dir, string home_dir,
 441                         string key, string fallback)
 442                 {
 443                         string env_path = internalGetEnvironmentVariable (key);
 444                         if (env_path != null && env_path != String.Empty) {
 445                                 return env_path;
 446                         }
 447
 448                         string user_dirs_path = Path.Combine (config_dir, "user-dirs.dirs");
 449
 450                         if (!File.Exists (user_dirs_path)) {
 451                                 return Path.Combine (home_dir, fallback);
 452                         }
 453
 454                         try {
 455                                 using(StreamReader reader = new StreamReader (user_dirs_path)) {
 456                                         string line;
 457                                         while ((line = reader.ReadLine ()) != null) {
 458                                                 line = line.Trim ();
 459                                                 int delim_index = line.IndexOf ('=');
 460                         if(delim_index > 8 && line.Substring (0, delim_index) == key) {
 461                             string path = line.Substring (delim_index + 1).Trim ('"');
 462                             bool relative = false;
 463
 464                             if (path.StartsWith ("$HOME/")) {
 465                                 relative = true;
 466                                 path = path.Substring (6);
 467                             } else if (!path.StartsWith ("/")) {
 468                                 relative = true;
 469                             }
 470
 471                             return relative ? Path.Combine (home_dir, path) : path;
 472                         }
 473                                         }
 474                                 }
 475                         } catch (FileNotFoundException) {
 476                         }
 477
 478                         return Path.Combine (home_dir, fallback);
 479                 }
 480
 481
 482                 // the security runtime (and maybe other parts of corlib) needs the
 483                 // information to initialize themselves before permissions can be checked
 484                 internal static string InternalGetFolderPath (SpecialFolder folder)
 485                 {
 486                         string home = internalGetHome ();
 487
 488                         // http://freedesktop.org/Standards/basedir-spec/basedir-spec-0.6.html
 489
 490                         // note: skip security check for environment variables
 491                         string data = internalGetEnvironmentVariable ("XDG_DATA_HOME");
 492                         if ((data == null) || (data == String.Empty)) {
 493                                 data = Path.Combine (home, ".local");
 494                                 data = Path.Combine (data, "share");
 495                         }
 496
 497                         // note: skip security check for environment variables
 498                         string config = internalGetEnvironmentVariable ("XDG_CONFIG_HOME");
 499                         if ((config == null) || (config == String.Empty)) {
 500                                 config = Path.Combine (home, ".config");
 501                         }
 502
 503                         switch (folder) {
 504 #if NET_1_1
 505                         // MyComputer is a virtual directory
 506                         case SpecialFolder.MyComputer:
 507                                 return String.Empty;
 508 #endif
 509                         // personal == ~
 510                         case SpecialFolder.Personal:
 511                                 return home;
 512                         // use FDO's CONFIG_HOME. This data will be synced across a network like the windows counterpart.
 513                         case SpecialFolder.ApplicationData:
 514                                 return config;
 515                         //use FDO's DATA_HOME. This is *NOT* synced
 516                         case SpecialFolder.LocalApplicationData:
 517                                 return data;
 518 #if NET_1_1
 519                         case SpecialFolder.Desktop:
 520 #endif
 521                         case SpecialFolder.DesktopDirectory:
 522                                 return ReadXdgUserDir (config, home, "XDG_DESKTOP_DIR", "Desktop");
 523
 524                         case SpecialFolder.MyMusic:
 525                                 return ReadXdgUserDir (config, home, "XDG_MUSIC_DIR", "Music");
 526
 527                         case SpecialFolder.MyPictures:
 528                                 return ReadXdgUserDir (config, home, "XDG_PICTURES_DIR", "Pictures");
 529
 530                         // these simply dont exist on Linux
 531                         // The spec says if a folder doesnt exist, we
 532                         // should return ""
 533                         case SpecialFolder.Favorites:
 534                         case SpecialFolder.Programs:
 535                         case SpecialFolder.SendTo:
 536                         case SpecialFolder.StartMenu:
 537                         case SpecialFolder.Startup:
 538                         case SpecialFolder.Templates:
 539                         case SpecialFolder.Cookies:
 540                         case SpecialFolder.History:
 541                         case SpecialFolder.InternetCache:
 542                         case SpecialFolder.Recent:
 543                         case SpecialFolder.CommonProgramFiles:
 544                         case SpecialFolder.ProgramFiles:
 545                         case SpecialFolder.System:
 546                                 return String.Empty;
 547                         // This is where data common to all users goes
 548                         case SpecialFolder.CommonApplicationData:
 549                                 return "/usr/share";
 550                         default:
 551                                 throw new ArgumentException ("Invalid SpecialFolder");
 552                         }
 553                 }
 554
 555                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 556                 public static string[] GetLogicalDrives ()
 557                 {
 558                         return GetLogicalDrivesInternal ();
 559                 }
 560
 561                 // FIXME: Anyone using this anywhere ?
 562                 static internal string GetResourceString (string s) { return String.Empty; }
 563
 564
 565 #if NET_2_0
 566                 public static string GetEnvironmentVariable (string variable, EnvironmentVariableTarget target)
 567                 {
 568                         switch (target) {
 569                         case EnvironmentVariableTarget.Process:
 570                                 return GetEnvironmentVariable (variable);
 571                         case EnvironmentVariableTarget.Machine:
 572                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 573                                 if (!IsRunningOnWindows)
 574                                         return null;
 575                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment")) {
 576                                         return env.GetValue (variable).ToString ();
 577                                 }
 578                         case EnvironmentVariableTarget.User:
 579                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 580                                 if (!IsRunningOnWindows)
 581                                         return null;
 582                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment", false)) {
 583                                         return env.GetValue (variable).ToString ();
 584                                 }
 585                         default:
 586                                 throw new ArgumentException ("target");
 587                         }
 588                 }
 589
 590                 public static IDictionary GetEnvironmentVariables (EnvironmentVariableTarget target)
 591                 {
 592                         IDictionary variables = (IDictionary)new Hashtable ();
 593                         switch (target) {
 594                         case EnvironmentVariableTarget.Process:
 595                                 variables = GetEnvironmentVariables ();
 596                                 break;
 597                         case EnvironmentVariableTarget.Machine:
 598                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 599                                 if (IsRunningOnWindows) {
 600                                         using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment")) {
 601                                                 string[] value_names = env.GetValueNames ();
 602                                                 foreach (string value_name in value_names)
 603                                                         variables.Add (value_name, env.GetValue (value_name));
 604                                         }
 605                                 }
 606                                 break;
 607                         case EnvironmentVariableTarget.User:
 608                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 609                                 if (IsRunningOnWindows) {
 610                                         using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment")) {
 611                                                 string[] value_names = env.GetValueNames ();
 612                                                 foreach (string value_name in value_names)
 613                                                         variables.Add (value_name, env.GetValue (value_name));
 614                                         }
 615                                 }
 616                                 break;
 617                         default:
 618                                 throw new ArgumentException ("target");
 619                         }
 620                         return variables;
 621                 }
 622
 623                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 624                 public static void SetEnvironmentVariable (string variable, string value)
 625                 {
 626                         SetEnvironmentVariable (variable, value, EnvironmentVariableTarget.Process);
 627                 }
 628
 629                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted = true)]
 630                 public static void SetEnvironmentVariable (string variable, string value, EnvironmentVariableTarget target)
 631                 {
 632                         if (variable == null)
 633                                 throw new ArgumentNullException ("variable");
 634                         if (variable == String.Empty)
 635                                 throw new ArgumentException ("String cannot be of zero length.", "variable");
 636                         if (variable.IndexOf ('=') != -1)
 637                                 throw new ArgumentException ("Environment variable name cannot contain an equal character.", "variable");
 638                         if (variable[0] == '\0')
 639                                 throw new ArgumentException ("The first char in the string is the null character.", "variable");
 640
 641                         switch (target) {
 642                         case EnvironmentVariableTarget.Process:
 643                                 InternalSetEnvironmentVariable (variable, value);
 644                                 break;
 645                         case EnvironmentVariableTarget.Machine:
 646                                 if (!IsRunningOnWindows)
 647                                         return;
 648                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment", true)) {
 649                                         if (value == null || value.Length == 0)
 650                                                 env.DeleteValue (variable, false);
 651                                         else
 652                                                 env.SetValue (variable, value);
 653                                 }
 654                                 break;
 655                         case EnvironmentVariableTarget.User:
 656                                 if (!IsRunningOnWindows)
 657                                         return;
 658                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment", true)) {
 659                                         if (value == null || value.Length == 0)
 660                                                 env.DeleteValue (variable, false);
 661                                         else
 662                                                 env.SetValue (variable, value);
 663                                 }
 664                                 break;
 665                         default:
 666                                 throw new ArgumentException ("target");
 667                         }
 668                 }
 669
 670                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 671                 internal static extern void InternalSetEnvironmentVariable (string variable, string value);
 672
 673                 public static extern int ProcessorCount {
 674                         [EnvironmentPermission (SecurityAction.Demand, Read="NUMBER_OF_PROCESSORS")]
 675                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 676                         get;
 677                 }
 678
 679                 [MonoTODO ("Not implemented")]
 680                 [SecurityPermission (SecurityAction.LinkDemand, UnmanagedCode=true)]
 681                 public static void FailFast (string message)
 682                 {
 683                         throw new NotImplementedException ();
 684                 }
 685 #endif
 686
 687                 // private methods
 688
 689                 internal static bool IsRunningOnWindows {
 690                         get { return ((int) Platform != 128); }
 691                 }
 692
 693                 private static string GacPath {
 694                         get {
 695                                 if (Environment.IsRunningOnWindows) {
 696                                         /* On windows, we don't know the path where mscorlib.dll will be installed */
 697                                         string corlibDir = new DirectoryInfo (Path.GetDirectoryName (typeof (int).Assembly.Location)).Parent.Parent.FullName;
 698                                         return Path.Combine (Path.Combine (corlibDir, "mono"), "gac");
 699                                 }
 700
 701                                 return Path.Combine (Path.Combine (internalGetGacPath (), "mono"), "gac");
 702                         }
 703                 }
 704
 705                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 706                 private extern static string [] GetLogicalDrivesInternal ();
 707
 708                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 709                 private extern static string [] GetEnvironmentVariableNames ();
 710
 711                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 712                 internal extern static string GetMachineConfigPath ();
 713
 714                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 715                 internal extern static string internalGetGacPath ();
 716
 717                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 718                 internal extern static string internalGetHome ();
 719         }
 720 }
 721