mcs/class/System.Web/System.Web/HttpRuntime.cs

   1 //
   2 // System.Web.HttpRuntime.cs
   3 //
   4 // Authors:
   5 //      Miguel de Icaza (miguel@novell.com)
   6 //      Marek Habersack <mhabersack@novell.com>
   7 //
   8 //
   9 // Copyright (C) 2005-2010 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 //
  32 // TODO: Call HttpRequest.CloseInputStream when we finish a request, as we are using the IntPtr stream.
  33 //
  34 using System.IO;
  35 using System.Text;
  36 using System.Globalization;
  37 using System.Collections;
  38 using System.Collections.Concurrent;
  39 using System.Reflection;
  40 using System.Security;
  41 using System.Security.Permissions;
  42 using System.Web.Caching;
  43 using System.Web.Configuration;
  44 using System.Web.Management;
  45 using System.Web.UI;
  46 using System.Web.Util;
  47 using Mono.Web.Util;
  48 using System.Threading;
  49 using System.CodeDom.Compiler;
  50 using System.Web.Compilation;
  51
  52 namespace System.Web
  53 {
  54         // CAS - no InheritanceDemand here as the class is sealed
  55         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  56         public sealed class HttpRuntime
  57         {
  58                 static bool domainUnloading;
  59                 static SplitOrderedList <string, string> registeredAssemblies;
  60                 static QueueManager queue_manager;
  61                 static TraceManager trace_manager;
  62                 static Cache cache;
  63                 static Cache internalCache;
  64                 static WaitCallback do_RealProcessRequest;
  65                 static HttpWorkerRequest.EndOfSendNotification end_of_send_cb;
  66                 static Exception initialException;
  67                 static bool firstRun;
  68                 static bool assemblyMappingEnabled;
  69                 static object assemblyMappingLock = new object ();
  70                 static object appOfflineLock = new object ();
  71                 static HttpRuntimeSection runtime_section;
  72
  73                 public HttpRuntime ()
  74                 {
  75
  76                 }
  77
  78                 static HttpRuntime ()
  79                 {
  80                         firstRun = true;
  81
  82                         try {
  83                                 WebConfigurationManager.Init ();
  84                                 SettingsMappingManager.Init ();
  85                                 runtime_section = (HttpRuntimeSection) WebConfigurationManager.GetSection ("system.web/httpRuntime");
  86                         } catch (Exception ex) {
  87                                 initialException = ex;
  88                         }
  89
  90                         // The classes in whose constructors exceptions may be thrown, should be handled the same way QueueManager
  91                         // and TraceManager are below. The constructors themselves MUST NOT throw any exceptions - we MUST be sure
  92                         // the objects are created here. The exceptions will be dealt with below, in RealProcessRequest.
  93                         queue_manager = new QueueManager ();
  94                         if (queue_manager.HasException) {
  95                                 if (initialException == null)
  96                                         initialException = queue_manager.InitialException;
  97                                 else {
  98                                         Console.Error.WriteLine ("Exception during QueueManager initialization:");
  99                                         Console.Error.WriteLine (queue_manager.InitialException);
 100                                 }
 101                         }
 102
 103                         trace_manager = new TraceManager ();
 104                         if (trace_manager.HasException) {
 105                                 if (initialException == null)
 106                                         initialException = trace_manager.InitialException;
 107                                 else {
 108                                         Console.Error.WriteLine ("Exception during TraceManager initialization:");
 109                                         Console.Error.WriteLine (trace_manager.InitialException);
 110                                 }
 111                         }
 112
 113                         registeredAssemblies = new SplitOrderedList <string, string> (StringComparer.Ordinal);
 114                         cache = new Cache ();
 115                         internalCache = new Cache ();
 116                         internalCache.DependencyCache = internalCache;
 117                         do_RealProcessRequest = new WaitCallback (state => {
 118                                 try {
 119                                         RealProcessRequest (state);
 120                                 } catch {}
 121                                 });
 122                         end_of_send_cb = new HttpWorkerRequest.EndOfSendNotification (EndOfSend);
 123                 }
 124
 125                 internal static SplitOrderedList <string, string> RegisteredAssemblies {
 126                         get { return registeredAssemblies; }
 127                 }
 128
 129 #region AppDomain handling
 130                 internal static bool DomainUnloading {
 131                         get { return domainUnloading; }
 132                 }
 133
 134                 [MonoDocumentationNote ("Currently returns path to the application root")]
 135                 public static string AspClientScriptPhysicalPath { get { return AppDomainAppPath; } }
 136
 137                 [MonoDocumentationNote ("Currently returns path to the application root")]
 138                 public static string AspClientScriptVirtualPath { get { return AppDomainAppVirtualPath; } }
 139
 140                 //
 141                 // http://radio.weblogs.com/0105476/stories/2002/07/12/executingAspxPagesWithoutAWebServer.html
 142                 //
 143                 public static string AppDomainAppId {
 144                         [AspNetHostingPermission (SecurityAction.Demand, Level = AspNetHostingPermissionLevel.High)]
 145                         get {
 146                                 //
 147                                 // This value should not change across invocations
 148                                 //
 149                                 string dirname = (string) AppDomain.CurrentDomain.GetData (".appId");
 150                                 if ((dirname != null) && (dirname.Length > 0) && SecurityManager.SecurityEnabled) {
 151                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 152                                 }
 153                                 return dirname;
 154                         }
 155                 }
 156
 157                 // Physical directory for the application
 158                 public static string AppDomainAppPath {
 159                         get {
 160                                 string dirname = (string) AppDomain.CurrentDomain.GetData (".appPath");
 161                                 if (SecurityManager.SecurityEnabled) {
 162                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 163                                 }
 164                                 return dirname;
 165                         }
 166                 }
 167
 168                 public static string AppDomainAppVirtualPath {
 169                         get {
 170                                 return (string) AppDomain.CurrentDomain.GetData (".appVPath");
 171                         }
 172                 }
 173
 174                 public static string AppDomainId {
 175                         [AspNetHostingPermission (SecurityAction.Demand, Level = AspNetHostingPermissionLevel.High)]
 176                         get {
 177                                 return (string) AppDomain.CurrentDomain.GetData (".domainId");
 178                         }
 179                 }
 180
 181                 public static string AspInstallDirectory {
 182                         get {
 183                                 string dirname = (string) AppDomain.CurrentDomain.GetData (".hostingInstallDir");
 184                                 if ((dirname != null) && (dirname.Length > 0) && SecurityManager.SecurityEnabled) {
 185                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 186                                 }
 187                                 return dirname;
 188                         }
 189                 }
 190 #endregion
 191
 192                 static string _actual_bin_directory;
 193                 public static string BinDirectory {
 194                         get {
 195                                 if (_actual_bin_directory == null) {
 196                                         string[] parts = AppDomain.CurrentDomain.SetupInformation.PrivateBinPath.Split (';');
 197                                         string mypath = AppDomainAppPath;
 198                                         string tmp;
 199
 200                                         foreach (string p in parts) {
 201                                                 tmp = Path.Combine (mypath, p);
 202                                                 if (Directory.Exists (tmp)) {
 203                                                         _actual_bin_directory = tmp;
 204                                                         break;
 205                                                 }
 206                                         }
 207
 208                                         if (_actual_bin_directory == null)
 209                                                 _actual_bin_directory = Path.Combine (mypath, "bin");
 210
 211                                         if (_actual_bin_directory [_actual_bin_directory.Length - 1] != Path.DirectorySeparatorChar)
 212                                                 _actual_bin_directory += Path.DirectorySeparatorChar;
 213                                 }
 214
 215                                 if (SecurityManager.SecurityEnabled)
 216                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, _actual_bin_directory).Demand ();
 217
 218                                 return _actual_bin_directory;
 219                         }
 220                 }
 221
 222                 public static Cache Cache {
 223                         get {
 224                                 return cache;
 225                         }
 226                 }
 227
 228                 internal static Cache InternalCache {
 229                         get {
 230                                 return internalCache;
 231                         }
 232                 }
 233
 234                 public static string ClrInstallDirectory {
 235                         get {
 236                                 string dirname = Path.GetDirectoryName (typeof (Object).Assembly.Location);
 237                                 if ((dirname != null) && (dirname.Length > 0) && SecurityManager.SecurityEnabled) {
 238                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 239                                 }
 240                                 return dirname;
 241                         }
 242                 }
 243
 244                 public static string CodegenDir {
 245                         get {
 246                                 string dirname = AppDomain.CurrentDomain.SetupInformation.DynamicBase;
 247                                 if (SecurityManager.SecurityEnabled) {
 248                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 249                                 }
 250                                 return dirname;
 251                         }
 252                 }
 253
 254                 public static bool IsOnUNCShare {
 255                         [AspNetHostingPermission (SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Low)]
 256                         get {
 257                                 return RuntimeHelpers.IsUncShare;
 258                         }
 259                 }
 260
 261                 public static string MachineConfigurationDirectory {
 262                         get {
 263                                 string dirname = Path.GetDirectoryName (ICalls.GetMachineConfigPath ());
 264                                 if ((dirname != null) && (dirname.Length > 0) && SecurityManager.SecurityEnabled) {
 265                                         new FileIOPermission (FileIOPermissionAccess.PathDiscovery, dirname).Demand ();
 266                                 }
 267                                 return dirname;
 268                         }
 269                 }
 270
 271                 internal static HttpRuntimeSection Section { get { return runtime_section; } }
 272
 273                 public static bool UsingIntegratedPipeline { get { return false; } }
 274
 275                 public static Version IISVersion {
 276                         get {
 277                                 // Null means not hosted by IIS
 278                                 return null;
 279                         }
 280                 }
 281
 282                 public static Version TargetFramework {
 283                         get {
 284                                 return runtime_section.TargetFramework;
 285                         }
 286                 }
 287
 288                 [SecurityPermission (SecurityAction.Demand, UnmanagedCode = true)]
 289                 public static void Close ()
 290                 {
 291                         // Remove all items from cache.
 292                 }
 293
 294                 internal static HttpWorkerRequest QueuePendingRequest (bool started_internally)
 295                 {
 296                         HttpWorkerRequest next = queue_manager.GetNextRequest (null);
 297                         if (next == null)
 298                                 return null;
 299
 300                         if (!started_internally) {
 301                                 next.StartedInternally = true;
 302                                 ThreadPool.QueueUserWorkItem (do_RealProcessRequest, next);
 303                                 return null;
 304                         }
 305                         return next;
 306                 }
 307
 308                 static readonly string[] app_offline_files = {"app_offline.htm", "App_Offline.htm", "APP_OFFLINE.HTM"};
 309                 static string app_offline_file;
 310
 311                 static bool AppIsOffline (HttpContext context)
 312                 {
 313                         if (!HttpApplicationFactory.ApplicationDisabled || app_offline_file == null)
 314                                 return false;
 315
 316                         HttpResponse response = context.Response;
 317                         response.Clear ();
 318                         response.ContentType = "text/html";
 319                         response.ExpiresAbsolute = DateTime.UtcNow;
 320                         response.StatusCode = 503;
 321                         response.TransmitFile (app_offline_file, true);
 322
 323                         context.Request.ReleaseResources ();
 324                         context.Response.ReleaseResources ();
 325                         HttpContext.Current = null;
 326                         HttpApplication.requests_total_counter.Increment ();
 327
 328                         return true;
 329                 }
 330
 331                 static void AppOfflineFileRenamed (object sender, RenamedEventArgs args)
 332                 {
 333                         AppOfflineFileChanged (sender, args);
 334                 }
 335
 336                 static void AppOfflineFileChanged (object sender, FileSystemEventArgs args)
 337                 {
 338                         lock (appOfflineLock) {
 339                                 bool offline;
 340
 341                                 switch (args.ChangeType) {
 342                                         case WatcherChangeTypes.Created:
 343                                         case WatcherChangeTypes.Changed:
 344                                                 offline = true;
 345                                                 break;
 346
 347                                         case WatcherChangeTypes.Deleted:
 348                                                 offline = false;
 349                                                 break;
 350
 351                                         case WatcherChangeTypes.Renamed:
 352                                                 RenamedEventArgs rargs = args as RenamedEventArgs;
 353
 354                                                 if (rargs != null &&
 355                                                     String.Compare (rargs.Name, "app_offline.htm", StringComparison.OrdinalIgnoreCase) == 0)
 356                                                         offline = true;
 357                                                 else
 358                                                         offline = false;
 359                                                 break;
 360
 361                                         default:
 362                                                 offline = false;
 363                                                 break;
 364                                 }
 365                                 SetOfflineMode (offline, args.FullPath);
 366                         }
 367                 }
 368
 369                 static void SetOfflineMode (bool offline, string filePath)
 370                 {
 371                         if (!offline) {
 372                                 app_offline_file = null;
 373                                 if (HttpApplicationFactory.ApplicationDisabled)
 374                                         HttpRuntime.UnloadAppDomain ();
 375                         } else {
 376                                 app_offline_file = filePath;
 377                                 HttpApplicationFactory.DisableWatchers ();
 378                                 HttpApplicationFactory.ApplicationDisabled = true;
 379                                 InternalCache.InvokePrivateCallbacks ();
 380                                 HttpApplicationFactory.Dispose ();
 381                         }
 382                 }
 383
 384                 static void SetupOfflineWatch ()
 385                 {
 386                         lock (appOfflineLock) {
 387                                 FileSystemEventHandler seh = new FileSystemEventHandler (AppOfflineFileChanged);
 388                                 RenamedEventHandler reh = new RenamedEventHandler (AppOfflineFileRenamed);
 389
 390                                 string app_dir = AppDomainAppPath;
 391                                 FileSystemWatcher watcher;
 392                                 string offlineFile = null, tmp;
 393
 394                                 foreach (string f in app_offline_files) {
 395                                         watcher = new FileSystemWatcher ();
 396                                         watcher.Path = Path.GetDirectoryName (app_dir);
 397                                         watcher.Filter = Path.GetFileName (f);
 398                                         watcher.NotifyFilter |= NotifyFilters.Size;
 399                                         watcher.Deleted += seh;
 400                                         watcher.Changed += seh;
 401                                         watcher.Created += seh;
 402                                         watcher.Renamed += reh;
 403                                         watcher.EnableRaisingEvents = true;
 404
 405                                         tmp = Path.Combine (app_dir, f);
 406                                         if (File.Exists (tmp))
 407                                                 offlineFile = tmp;
 408                                 }
 409
 410                                 if (offlineFile != null)
 411                                         SetOfflineMode (true, offlineFile);
 412                         }
 413                 }
 414
 415                 static void RealProcessRequest (object o)
 416                 {
 417                         if (domainUnloading) {
 418                                 Console.Error.WriteLine ("Domain is unloading, not processing the request.");
 419                                 return;
 420                         }
 421
 422                         HttpWorkerRequest req = (HttpWorkerRequest) o;
 423                         bool started_internally = req.StartedInternally;
 424                         do {
 425                                 Process (req);
 426                                 req = QueuePendingRequest (started_internally);
 427                         } while (started_internally && req != null);
 428                 }
 429
 430                 static void Process (HttpWorkerRequest req)
 431                 {
 432                         bool error = false;
 433                         if (firstRun) {
 434                                 firstRun = false;
 435                                 if (initialException != null) {
 436                                         FinishWithException (req, HttpException.NewWithCode ("Initial exception", initialException, WebEventCodes.RuntimeErrorRequestAbort));
 437                                         error = true;
 438                                 }
 439                                 SetupOfflineWatch ();
 440                         }
 441                         HttpContext context = new HttpContext (req);
 442                         HttpContext.Current = context;
 443                         if (AppIsOffline (context))
 444                                 return;
 445
 446                         //
 447                         // Get application instance (create or reuse an instance of the correct class)
 448                         //
 449                         HttpApplication app = null;
 450                         if (!error) {
 451                                 try {
 452                                         app = HttpApplicationFactory.GetApplication (context);
 453                                 } catch (Exception e) {
 454                                         FinishWithException (req, HttpException.NewWithCode (String.Empty, e, WebEventCodes.RuntimeErrorRequestAbort));
 455                                         error = true;
 456                                 }
 457                         }
 458
 459                         if (error) {
 460                                 context.Request.ReleaseResources ();
 461                                 context.Response.ReleaseResources ();
 462                                 HttpContext.Current = null;
 463                         } else {
 464                                 context.ApplicationInstance = app;
 465                                 req.SetEndOfSendNotification (end_of_send_cb, context);
 466
 467                                 //
 468                                 // Ask application to service the request
 469                                 //
 470
 471                                 IHttpHandler ihh = app;
 472 //                              IAsyncResult appiar = ihah.BeginProcessRequest (context, new AsyncCallback (request_processed), context);
 473 //                              ihah.EndProcessRequest (appiar);
 474                                 ihh.ProcessRequest (context);
 475
 476                                 HttpApplicationFactory.Recycle (app);
 477                         }
 478                 }
 479
 480                 static void EndOfSend (HttpWorkerRequest ignored1, object ignored2)
 481                 {
 482                 }
 483
 484                 //
 485                 // ProcessRequest method is executed in the AppDomain of the application
 486                 //
 487                 // Observations:
 488                 //    ProcessRequest does not guarantee that `wr' will be processed synchronously,
 489                 //    the request can be queued and processed later.
 490                 //
 491                 [AspNetHostingPermission (SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Medium)]
 492                 public static void ProcessRequest (HttpWorkerRequest wr)
 493                 {
 494                         if (wr == null)
 495                                 throw new ArgumentNullException ("wr");
 496                         //
 497                         // Queue our request, fetch the next available one from the queue
 498                         //
 499                         HttpWorkerRequest request = queue_manager.GetNextRequest (wr);
 500                         if (request == null)
 501                                 return;
 502
 503                         QueuePendingRequest (false);
 504                         RealProcessRequest (request);
 505                 }
 506
 507
 508                 //
 509                 // Called when we are shutting down or we need to reload an application
 510                 // that has been modified (touch global.asax)
 511                 //
 512                 [SecurityPermission (SecurityAction.Demand, UnmanagedCode = true)]
 513                 public static void UnloadAppDomain ()
 514                 {
 515                         //
 516                         // TODO: call ReleaseResources
 517                         //
 518                         domainUnloading = true;
 519                         HttpApplicationFactory.DisableWatchers ();
 520                         ThreadPool.QueueUserWorkItem (delegate {
 521                                 try {
 522                                         ShutdownAppDomain ();
 523                                 } catch (Exception e){
 524                                         Console.Error.WriteLine (e);
 525                                 }
 526                         });
 527                 }
 528                 //
 529                 // Shuts down the AppDomain
 530                 //
 531                 static void ShutdownAppDomain ()
 532                 {
 533                         queue_manager.Dispose ();
 534                         // This will call Session_End if needed.
 535                         InternalCache.InvokePrivateCallbacks ();
 536                         // Kill our application.
 537                         HttpApplicationFactory.Dispose ();
 538                         ThreadPool.QueueUserWorkItem (delegate {
 539                                 try {
 540                                         DoUnload ();
 541                                 } catch {
 542                                 }});
 543                 }
 544
 545                 static void DoUnload ()
 546                 {
 547                         AppDomain.Unload (AppDomain.CurrentDomain);
 548                 }
 549
 550                 static string content503 = "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n" +
 551                         "<html><head>\n<title>503 Server Unavailable</title>\n</head><body>\n" +
 552                         "<h1>Server Unavailable</h1>\n" +
 553                         "</body></html>\n";
 554
 555                 static void FinishWithException (HttpWorkerRequest wr, HttpException e)
 556                 {
 557                         int code = e.GetHttpCode ();
 558                         wr.SendStatus (code, HttpWorkerRequest.GetStatusDescription (code));
 559                         wr.SendUnknownResponseHeader ("Connection", "close");
 560                         Encoding enc = Encoding.ASCII;
 561                         wr.SendUnknownResponseHeader ("Content-Type", "text/html; charset=" + enc.WebName);
 562                         string msg = e.GetHtmlErrorMessage ();
 563                         byte [] contentBytes = enc.GetBytes (msg);
 564                         wr.SendUnknownResponseHeader ("Content-Length", contentBytes.Length.ToString ());
 565                         wr.SendResponseFromMemory (contentBytes, contentBytes.Length);
 566                         wr.FlushResponse (true);
 567                         wr.CloseConnection ();
 568                         HttpApplication.requests_total_counter.Increment ();
 569                 }
 570
 571                 //
 572                 // This is called from the QueueManager if a request
 573                 // can not be processed (load, no resources, or
 574                 // appdomain unload).
 575                 //
 576                 static internal void FinishUnavailable (HttpWorkerRequest wr)
 577                 {
 578                         wr.SendStatus (503, "Service unavailable");
 579                         wr.SendUnknownResponseHeader ("Connection", "close");
 580                         Encoding enc = Encoding.ASCII;
 581                         wr.SendUnknownResponseHeader ("Content-Type", "text/html; charset=" + enc.WebName);
 582                         byte [] contentBytes = enc.GetBytes (content503);
 583                         wr.SendUnknownResponseHeader ("Content-Length", contentBytes.Length.ToString ());
 584                         wr.SendResponseFromMemory (contentBytes, contentBytes.Length);
 585                         wr.FlushResponse (true);
 586                         wr.CloseConnection ();
 587                         HttpApplication.requests_total_counter.Increment ();
 588                 }
 589
 590                 [AspNetHostingPermissionAttribute(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Unrestricted)]
 591                 [MonoDocumentationNote ("Always returns null on Mono")]
 592                 public static NamedPermissionSet GetNamedPermissionSet ()
 593                 {
 594                         return null;
 595                 }
 596
 597                 static internal void WritePreservationFile (Assembly asm, string genericNameBase)
 598                 {
 599                         if (asm == null)
 600                                 throw new ArgumentNullException ("asm");
 601                         if (String.IsNullOrEmpty (genericNameBase))
 602                                 throw new ArgumentNullException ("genericNameBase");
 603
 604                         string compiled = Path.Combine (AppDomain.CurrentDomain.SetupInformation.DynamicBase,
 605                                                         genericNameBase + ".compiled");
 606                         PreservationFile pf = new PreservationFile ();
 607                         try {
 608                                 pf.VirtualPath = String.Concat ("/", genericNameBase, "/");
 609
 610                                 AssemblyName an = asm.GetName ();
 611                                 pf.Assembly = an.Name;
 612                                 pf.ResultType = BuildResultTypeCode.TopLevelAssembly;
 613                                 pf.Save (compiled);
 614                         } catch (Exception ex) {
 615                                 throw new HttpException (
 616                                         String.Format ("Failed to write preservation file {0}", genericNameBase + ".compiled"),
 617                                         ex);
 618                         }
 619                 }
 620
 621                 static Assembly ResolveAssemblyHandler(object sender, ResolveEventArgs e)
 622                 {
 623                         AssemblyName an = new AssemblyName (e.Name);
 624                         string dynamic_base = AppDomain.CurrentDomain.SetupInformation.DynamicBase;
 625                         string compiled = Path.Combine (dynamic_base, an.Name + ".compiled");
 626                         string asmPath;
 627
 628                         if (!File.Exists (compiled)) {
 629                                 string fn = an.FullName;
 630                                 if (!RegisteredAssemblies.Find ((uint)fn.GetHashCode (), fn, out asmPath))
 631                                         return null;
 632                         } else {
 633                                 PreservationFile pf;
 634                                 try {
 635                                         pf = new PreservationFile (compiled);
 636                                 } catch (Exception ex) {
 637                                         throw new HttpException (
 638                                                 String.Format ("Failed to read preservation file {0}", an.Name + ".compiled"),
 639                                                 ex);
 640                                 }
 641                                 asmPath = Path.Combine (dynamic_base, pf.Assembly + ".dll");
 642                         }
 643
 644                         if (String.IsNullOrEmpty (asmPath))
 645                                 return null;
 646
 647                         Assembly ret = null;
 648                         try {
 649                                 ret = Assembly.LoadFrom (asmPath);
 650                         } catch (Exception) {
 651                                 // ignore
 652                         }
 653
 654                         return ret;
 655                 }
 656
 657                 internal static void EnableAssemblyMapping (bool enable)
 658                 {
 659                         lock (assemblyMappingLock) {
 660                                 if (assemblyMappingEnabled == enable)
 661                                         return;
 662                                 if (enable)
 663                                         AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler (ResolveAssemblyHandler);
 664                                 else
 665                                         AppDomain.CurrentDomain.AssemblyResolve -= new ResolveEventHandler (ResolveAssemblyHandler);
 666                                 assemblyMappingEnabled = enable;
 667                         }
 668                 }
 669
 670                 internal static TraceManager TraceManager {
 671                         get {
 672                                 return trace_manager;
 673                         }
 674                 }
 675         }
 676 }