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 = 77;
  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                                         os = new OperatingSystem (p, v);
 191                                 }
 192                                 return os;
 193                         }
 194                 }
 195
 196                 /// <summary>
 197                 /// Get StackTrace
 198                 /// </summary>
 199                 public static string StackTrace {
 200                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 201                         get {
 202                                 System.Diagnostics.StackTrace trace = new System.Diagnostics.StackTrace (0, true);
 203                                 return trace.ToString ();
 204                         }
 205                 }
 206 #if !NET_2_1
 207                 /// <summary>
 208                 /// Get a fully qualified path to the system directory
 209                 /// </summary>
 210                 public static string SystemDirectory {
 211                         get {
 212                                 return GetFolderPath (SpecialFolder.System);
 213                         }
 214                 }
 215 #endif
 216                 /// <summary>
 217                 /// Get the number of milliseconds that have elapsed since the system was booted
 218                 /// </summary>
 219                 public extern static int TickCount {
 220                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 221                         get;
 222                 }
 223
 224                 /// <summary>
 225                 /// Get UserDomainName
 226                 /// </summary>
 227                 public static string UserDomainName {
 228                         // FIXME: this variable doesn't exist (at least not on WinXP) - reported to MS as FDBK20562
 229                         [EnvironmentPermission (SecurityAction.Demand, Read="USERDOMAINNAME")]
 230                         get {
 231                                 return MachineName;
 232                         }
 233                 }
 234
 235                 /// <summary>
 236                 /// Gets a flag indicating whether the process is in interactive mode
 237                 /// </summary>
 238                 [MonoTODO ("Currently always returns false, regardless of interactive state")]
 239                 public static bool UserInteractive {
 240                         get {
 241                                 return false;
 242                         }
 243                 }
 244
 245                 /// <summary>
 246                 /// Get the user name of current process is running under
 247                 /// </summary>
 248                 public extern static string UserName {
 249                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 250                         [EnvironmentPermission (SecurityAction.Demand, Read="USERNAME;USER")]
 251                         get;
 252                 }
 253
 254                 /// <summary>
 255                 /// Get the version of the common language runtime
 256                 /// </summary>
 257                 public static Version Version {
 258                         get {
 259                                 return new Version (Consts.FxFileVersion);
 260                         }
 261                 }
 262
 263                 /// <summary>
 264                 /// Get the amount of physical memory mapped to process
 265                 /// </summary>
 266                 [MonoTODO ("Currently always returns zero")]
 267                 public static long WorkingSet {
 268                         [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 269                         get { return 0; }
 270                 }
 271
 272                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 273                 [SecurityPermission (SecurityAction.Demand, UnmanagedCode=true)]
 274                 public extern static void Exit (int exitCode);
 275
 276                 /// <summary>
 277                 /// Substitute environment variables in the argument "name"
 278                 /// </summary>
 279                 public static string ExpandEnvironmentVariables (string name)
 280                 {
 281                         if (name == null)
 282                                 throw new ArgumentNullException ("name");
 283
 284                         int off1 = name.IndexOf ('%');
 285                         if (off1 == -1)
 286                                 return name;
 287
 288                         int len = name.Length;
 289                         int off2 = 0;
 290                         if (off1 == len - 1 || (off2 = name.IndexOf ('%', off1 + 1)) == -1)
 291                                 return name;
 292
 293                         StringBuilder result = new StringBuilder ();
 294                         result.Append (name, 0, off1);
 295                         Hashtable tbl = null;
 296                         do {
 297                                 string var = name.Substring (off1 + 1, off2 - off1 - 1);
 298                                 string value = GetEnvironmentVariable (var);
 299                                 if (value == null && Environment.IsRunningOnWindows) {
 300                                         // On windows, env. vars. are case insensitive
 301                                         if (tbl == null)
 302                                                 tbl = GetEnvironmentVariablesNoCase ();
 303
 304                                         value = tbl [var] as string;
 305                                 }
 306
 307                                 // If value not found, add %FOO to stream,
 308                                 //  and use the closing % for the next iteration.
 309                                 // If value found, expand it in place of %FOO%
 310                                 if (value == null) {
 311                                         result.Append ('%');
 312                                         result.Append (var);
 313                                         off2--;
 314                                 } else {
 315                                         result.Append (value);
 316                                 }
 317                                 int oldOff2 = off2;
 318                                 off1 = name.IndexOf ('%', off2 + 1);
 319                                 // If no % found for off1, don't look for one for off2
 320                                 off2 = (off1 == -1 || off2 > len-1)? -1 :name.IndexOf ('%', off1 + 1);
 321                                 // textLen is the length of text between the closing % of current iteration
 322                                 //  and the starting % of the next iteration if any. This text is added to output
 323                                 int textLen;
 324                                 // If no new % found, use all the remaining text
 325                                 if (off1 == -1 || off2 == -1)
 326                                         textLen = len - oldOff2 - 1;
 327                                 // If value found in current iteration, use text after current closing % and next %
 328                                 else if(value != null)
 329                                         textLen = off1 - oldOff2 - 1;
 330                                 // If value not found in current iteration, but a % was found for next iteration,
 331                                 //  use text from current closing % to the next %.
 332                                 else
 333                                         textLen = off1 - oldOff2;
 334                                 if(off1 >= oldOff2 || off1 == -1)
 335                                         result.Append (name, oldOff2+1, textLen);
 336                         } while (off2 > -1 && off2 < len);
 337
 338                         return result.ToString ();
 339
 340                 }
 341
 342                 /// <summary>
 343                 /// Return an array of the command line arguments of the current process
 344                 /// </summary>
 345                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 346                 [EnvironmentPermissionAttribute (SecurityAction.Demand, Read = "PATH")]
 347                 public extern static string[] GetCommandLineArgs ();
 348
 349                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 350                 internal extern static string internalGetEnvironmentVariable (string variable);
 351
 352                 /// <summary>
 353                 /// Return a string containing the value of the environment
 354                 /// variable identifed by parameter "variable"
 355                 /// </summary>
 356                 public static string GetEnvironmentVariable (string variable)
 357                 {
 358                         if (SecurityManager.SecurityEnabled) {
 359                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, variable).Demand ();
 360                         }
 361                         return internalGetEnvironmentVariable (variable);
 362                 }
 363
 364                 static Hashtable GetEnvironmentVariablesNoCase ()
 365                 {
 366                         Hashtable vars = new Hashtable (CaseInsensitiveHashCodeProvider.Default,
 367                                                         CaseInsensitiveComparer.Default);
 368
 369                         foreach (string name in GetEnvironmentVariableNames ()) {
 370                                 vars [name] = internalGetEnvironmentVariable (name);
 371                         }
 372
 373                         return vars;
 374                 }
 375
 376                 /// <summary>
 377                 /// Return a set of all environment variables and their values
 378                 /// </summary>
 379 #if NET_2_0
 380                 public static IDictionary GetEnvironmentVariables ()
 381                 {
 382                         StringBuilder sb = null;
 383                         if (SecurityManager.SecurityEnabled) {
 384                                 // we must have access to each variable to get the lot
 385                                 sb = new StringBuilder ();
 386                                 // but (performance-wise) we do not want a stack-walk
 387                                 // for each of them so we concatenate them
 388                         }
 389
 390                         Hashtable vars = new Hashtable ();
 391                         foreach (string name in GetEnvironmentVariableNames ()) {
 392                                 vars [name] = internalGetEnvironmentVariable (name);
 393                                 if (sb != null) {
 394                                         sb.Append (name);
 395                                         sb.Append (";");
 396                                 }
 397                         }
 398
 399                         if (sb != null) {
 400                                 new EnvironmentPermission (EnvironmentPermissionAccess.Read, sb.ToString ()).Demand ();
 401                         }
 402                         return vars;
 403                 }
 404 #else
 405                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 406                 public static IDictionary GetEnvironmentVariables ()
 407                 {
 408                         Hashtable vars = new Hashtable ();
 409                         foreach (string name in GetEnvironmentVariableNames ()) {
 410                                 vars [name] = internalGetEnvironmentVariable (name);
 411                         }
 412                         return vars;
 413                 }
 414 #endif
 415
 416                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 417                 private extern static string GetWindowsFolderPath (int folder);
 418
 419                 /// <summary>
 420                 /// Returns the fully qualified path of the
 421                 /// folder specified by the "folder" parameter
 422                 /// </summary>
 423                 public static string GetFolderPath (SpecialFolder folder)
 424                 {
 425                         string dir = null;
 426
 427                         if (Environment.IsRunningOnWindows) {
 428                                 dir = GetWindowsFolderPath ((int) folder);
 429                         } else {
 430                                 dir = InternalGetFolderPath (folder);
 431                         }
 432
 433                         if ((dir != null) && (dir.Length > 0) && SecurityManager.SecurityEnabled) {
 434                                 new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dir).Demand ();
 435                         }
 436                         return dir;
 437                 }
 438
 439                 private static string ReadXdgUserDir (string config_dir, string home_dir,
 440                         string key, string fallback)
 441                 {
 442                         string env_path = internalGetEnvironmentVariable (key);
 443                         if (env_path != null && env_path != String.Empty) {
 444                                 return env_path;
 445                         }
 446
 447                         string user_dirs_path = Path.Combine (config_dir, "user-dirs.dirs");
 448
 449                         if (!File.Exists (user_dirs_path)) {
 450                                 return Path.Combine (home_dir, fallback);
 451                         }
 452
 453                         try {
 454                                 using(StreamReader reader = new StreamReader (user_dirs_path)) {
 455                                         string line;
 456                                         while ((line = reader.ReadLine ()) != null) {
 457                                                 line = line.Trim ();
 458                                                 int delim_index = line.IndexOf ('=');
 459                         if(delim_index > 8 && line.Substring (0, delim_index) == key) {
 460                             string path = line.Substring (delim_index + 1).Trim ('"');
 461                             bool relative = false;
 462
 463                             if (path.StartsWith ("$HOME/")) {
 464                                 relative = true;
 465                                 path = path.Substring (6);
 466                             } else if (!path.StartsWith ("/")) {
 467                                 relative = true;
 468                             }
 469
 470                             return relative ? Path.Combine (home_dir, path) : path;
 471                         }
 472                                         }
 473                                 }
 474                         } catch (FileNotFoundException) {
 475                         }
 476
 477                         return Path.Combine (home_dir, fallback);
 478                 }
 479
 480
 481                 // the security runtime (and maybe other parts of corlib) needs the
 482                 // information to initialize themselves before permissions can be checked
 483                 internal static string InternalGetFolderPath (SpecialFolder folder)
 484                 {
 485                         string home = internalGetHome ();
 486
 487                         // http://freedesktop.org/Standards/basedir-spec/basedir-spec-0.6.html
 488
 489                         // note: skip security check for environment variables
 490                         string data = internalGetEnvironmentVariable ("XDG_DATA_HOME");
 491                         if ((data == null) || (data == String.Empty)) {
 492                                 data = Path.Combine (home, ".local");
 493                                 data = Path.Combine (data, "share");
 494                         }
 495
 496                         // note: skip security check for environment variables
 497                         string config = internalGetEnvironmentVariable ("XDG_CONFIG_HOME");
 498                         if ((config == null) || (config == String.Empty)) {
 499                                 config = Path.Combine (home, ".config");
 500                         }
 501
 502                         switch (folder) {
 503 #if NET_1_1
 504                         // MyComputer is a virtual directory
 505                         case SpecialFolder.MyComputer:
 506                                 return String.Empty;
 507 #endif
 508                         // personal == ~
 509                         case SpecialFolder.Personal:
 510                                 return home;
 511                         // use FDO's CONFIG_HOME. This data will be synced across a network like the windows counterpart.
 512                         case SpecialFolder.ApplicationData:
 513                                 return config;
 514                         //use FDO's DATA_HOME. This is *NOT* synced
 515                         case SpecialFolder.LocalApplicationData:
 516                                 return data;
 517 #if NET_1_1
 518                         case SpecialFolder.Desktop:
 519 #endif
 520                         case SpecialFolder.DesktopDirectory:
 521                                 return ReadXdgUserDir (config, home, "XDG_DESKTOP_DIR", "Desktop");
 522
 523                         case SpecialFolder.MyMusic:
 524                                 return ReadXdgUserDir (config, home, "XDG_MUSIC_DIR", "Music");
 525
 526                         case SpecialFolder.MyPictures:
 527                                 return ReadXdgUserDir (config, home, "XDG_PICTURES_DIR", "Pictures");
 528
 529                         // these simply dont exist on Linux
 530                         // The spec says if a folder doesnt exist, we
 531                         // should return ""
 532                         case SpecialFolder.Favorites:
 533                         case SpecialFolder.Programs:
 534                         case SpecialFolder.SendTo:
 535                         case SpecialFolder.StartMenu:
 536                         case SpecialFolder.Startup:
 537                         case SpecialFolder.Templates:
 538                         case SpecialFolder.Cookies:
 539                         case SpecialFolder.History:
 540                         case SpecialFolder.InternetCache:
 541                         case SpecialFolder.Recent:
 542                         case SpecialFolder.CommonProgramFiles:
 543                         case SpecialFolder.ProgramFiles:
 544                         case SpecialFolder.System:
 545                                 return String.Empty;
 546                         // This is where data common to all users goes
 547                         case SpecialFolder.CommonApplicationData:
 548                                 return "/usr/share";
 549                         default:
 550                                 throw new ArgumentException ("Invalid SpecialFolder");
 551                         }
 552                 }
 553
 554                 [EnvironmentPermission (SecurityAction.Demand, Unrestricted=true)]
 555                 public static string[] GetLogicalDrives ()
 556                 {
 557                         return GetLogicalDrivesInternal ();
 558                 }
 559
 560 #if NET_2_0 && !NET_2_1
 561                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 562                 private static extern void internalBroadcastSettingChange ();
 563
 564                 public static string GetEnvironmentVariable (string variable, EnvironmentVariableTarget target)
 565                 {
 566                         switch (target) {
 567                         case EnvironmentVariableTarget.Process:
 568                                 return GetEnvironmentVariable (variable);
 569                         case EnvironmentVariableTarget.Machine:
 570                                 new EnvironmentPermission (PermissionState.Unrestricted).Demand ();
 571                                 if (!IsRunningOnWindows)
 572                                         return null;
 573                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.LocalMachine.OpenSubKey (@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment")) {
 574                                         object regvalue = env.GetValue (variable);
 575                                         return (regvalue == null) ? null : regvalue.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                                         object regvalue = env.GetValue (variable);
 583                                         return (regvalue == null) ? null : regvalue.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 (String.IsNullOrEmpty (value))
 650                                                 env.DeleteValue (variable, false);
 651                                         else
 652                                                 env.SetValue (variable, value);
 653                                         internalBroadcastSettingChange ();
 654                                 }
 655                                 break;
 656                         case EnvironmentVariableTarget.User:
 657                                 if (!IsRunningOnWindows)
 658                                         return;
 659                                 using (Microsoft.Win32.RegistryKey env = Microsoft.Win32.Registry.CurrentUser.OpenSubKey ("Environment", true)) {
 660                                         if (String.IsNullOrEmpty (value))
 661                                                 env.DeleteValue (variable, false);
 662                                         else
 663                                                 env.SetValue (variable, value);
 664                                         internalBroadcastSettingChange ();
 665                                 }
 666                                 break;
 667                         default:
 668                                 throw new ArgumentException ("target");
 669                         }
 670                 }
 671
 672                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 673                 internal static extern void InternalSetEnvironmentVariable (string variable, string value);
 674
 675                 [MonoTODO ("Not implemented")]
 676                 [SecurityPermission (SecurityAction.LinkDemand, UnmanagedCode=true)]
 677                 public static void FailFast (string message)
 678                 {
 679                         throw new NotImplementedException ();
 680                 }
 681 #endif
 682 #if NET_2_0
 683                 public static extern int ProcessorCount {
 684                         [EnvironmentPermission (SecurityAction.Demand, Read="NUMBER_OF_PROCESSORS")]
 685                         [MethodImplAttribute (MethodImplOptions.InternalCall)]
 686                         get;
 687                 }
 688 #endif
 689                 // private methods
 690
 691                 internal static bool IsRunningOnWindows {
 692                         get { return ((int) Platform < 4); }
 693                 }
 694 #if !NET_2_1
 695                 //
 696                 // Used by gacutil.exe
 697                 //
 698 #pragma warning disable 169
 699                 private static string GacPath {
 700                         get {
 701                                 if (Environment.IsRunningOnWindows) {
 702                                         /* On windows, we don't know the path where mscorlib.dll will be installed */
 703                                         string corlibDir = new DirectoryInfo (Path.GetDirectoryName (typeof (int).Assembly.Location)).Parent.Parent.FullName;
 704                                         return Path.Combine (Path.Combine (corlibDir, "mono"), "gac");
 705                                 }
 706
 707                                 return Path.Combine (Path.Combine (internalGetGacPath (), "mono"), "gac");
 708                         }
 709                 }
 710 #pragma warning restore 169
 711                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 712                 internal extern static string internalGetGacPath ();
 713 #endif
 714                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 715                 private extern static string [] GetLogicalDrivesInternal ();
 716
 717                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 718                 private extern static string [] GetEnvironmentVariableNames ();
 719
 720                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 721                 internal extern static string GetMachineConfigPath ();
 722
 723                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 724                 internal extern static string internalGetHome ();
 725         }
 726 }
 727