context: //
  // System.Web.Hosting.ApplicationHost.cs 
  // 
  // Author:
  //	Miguel de Icaza (miguel@novell.com)
  //
  //
  // Copyright (C) 2005 Novell, Inc (http://www.novell.com)
  //
  // Permission is hereby granted, free of charge, to any person obtaining
  // a copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to
  // permit persons to whom the Software is furnished to do so, subject to
  // the following conditions:
  // 
  // The above copyright notice and this permission notice shall be
  // included in all copies or substantial portions of the Software.
  // 
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  //
  
  using System.Configuration;
  using System.IO;
  using System.Security.Permissions;
  using System.Security.Policy;
  using System.Text;
  using System.Web.Configuration;
  
  namespace System.Web.Hosting {
  
  	// CAS - no InheritanceDemand here as the class is sealed
  	[AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  	public sealed class ApplicationHost {
  		const string DEFAULT_WEB_CONFIG_NAME = "web.config";
  		internal const string MonoHostedDataKey = ".:!MonoAspNetHostedApp!:.";
  
  		static object create_dir = new object ();
  
  		ApplicationHost ()
  		{
  		}
  
  		internal static string FindWebConfig (string basedir)
  		{
  			if (String.IsNullOrEmpty (basedir) || !Directory.Exists (basedir))
  				return null;
  
  			string[] files = Directory.GetFileSystemEntries (basedir, "?eb.?onfig");
  			if (files == null || files.Length == 0)
  				return null;
  			return files [0];
  		}
  
  		internal static bool ClearDynamicBaseDirectory (string directory)
  		{
  			string[] entries = null;
  			
  			try {
  				entries = Directory.GetDirectories (directory);
  			} catch {
  				// ignore
  			}
  
  			bool dirEmpty = true;
  			if (entries != null && entries.Length > 0) {
  				foreach (string e in entries) {
  					if (ClearDynamicBaseDirectory (e)) {
  						try {
  							Directory.Delete (e);
  						} catch {
  							dirEmpty = false;
  						}
  					}
  				}
  			}
  
  			try {
  				entries = Directory.GetFiles (directory);
  			} catch {
  				entries = null;
  			}
  
  			if (entries != null && entries.Length > 0) {
  				foreach (string e in entries) {
  					try {
  						File.Delete (e);
  					} catch {
  						dirEmpty = false;
  					}
  				}
  			}
  
  			return dirEmpty;
  		}
  		
  		static bool CreateDirectory (string directory)
  		{
  			lock (create_dir) {
  				if (!Directory.Exists (directory)) {
  					Directory.CreateDirectory (directory);
  					return false;
  				} else
  					return true;
  			}
  		}
  
  		static string BuildPrivateBinPath (string physicalPath, string[] dirs)
  		{
  			int len = dirs.Length;
  			string[] ret = new string [len];
  			for (int i = 0; i < len; i++)
  				ret [i] = Path.Combine (physicalPath, dirs [i]);
  			return String.Join (";", ret);
  		}
  		
  		//
  		// For further details see `Hosting the ASP.NET runtime'
  		//
  		//    http://www.west-wind.com/presentations/aspnetruntime/aspnetruntime.asp
  		// 
  		[SecurityPermission (SecurityAction.Demand, UnmanagedCode = true)]
  		public static object CreateApplicationHost (Type hostType, string virtualDir, string physicalDir)
  		{
  			if (physicalDir == null)
  				throw new NullReferenceException ();
  
  			// Make sure physicalDir has file system semantics
  			// and not uri semantics ( '\' and not '/' ).
  			physicalDir = Path.GetFullPath (physicalDir);
  
  			if (hostType == null)
  				throw new ArgumentException ("hostType can't be null");
  
  			if (virtualDir == null)
  				throw new ArgumentNullException ("virtualDir");
  
  			Evidence evidence = new Evidence (AppDomain.CurrentDomain.Evidence);
  			
  			//
  			// Setup
  			//
  			AppDomainSetup setup = new AppDomainSetup ();
  
  			setup.ApplicationBase = physicalDir;
  
  			string webConfig = FindWebConfig (physicalDir);
  
  			if (webConfig == null)
  				webConfig = Path.Combine (physicalDir, DEFAULT_WEB_CONFIG_NAME);
  			setup.ConfigurationFile = webConfig;
  			setup.DisallowCodeDownload = true;
  
  			string[] bindirPath = new string [1] { Path.Combine (physicalDir, "bin") };
  			string bindir;
  
  			foreach (string dir in HttpApplication.BinDirs) {
  				bindir = Path.Combine (physicalDir, dir);
  			
  				if (Directory.Exists (bindir)) {
  					bindirPath [0] = bindir;
  					break;
  				}
  			}
  
  			setup.PrivateBinPath = BuildPrivateBinPath (physicalDir, bindirPath);
  			setup.PrivateBinPathProbe = "*";
  			string dynamic_dir = null;
  			string user = Environment.UserName;
  			int tempDirTag = 0;
  			string dirPrefix = String.Concat (user, "-temp-aspnet-");
  			
  			for (int i = 0; ; i++){
  				string d = Path.Combine (Path.GetTempPath (), String.Concat (dirPrefix, i.ToString ("x")));
  			
  				try {
  					CreateDirectory (d);
  					string stamp = Path.Combine (d, "stamp");
  					CreateDirectory (stamp);
  					dynamic_dir = d;
  					try {
  						Directory.Delete (stamp);
  					} catch (Exception) {
  						// ignore
  					}
  					
  					tempDirTag = i.GetHashCode ();
  					break;
  				} catch (UnauthorizedAccessException){
  					continue;
  				}
  			}
  			// 
  			// Unique Domain ID
  			//
  			string domain_id = (virtualDir.GetHashCode () + 1 ^ physicalDir.GetHashCode () + 2 ^ tempDirTag).ToString ("x");
  
  			// This is used by mod_mono's fail-over support
  			string domain_id_suffix = Environment.GetEnvironmentVariable ("__MONO_DOMAIN_ID_SUFFIX");
  			if (domain_id_suffix != null && domain_id_suffix.Length > 0)
  				domain_id += domain_id_suffix;
  			
  			setup.ApplicationName = domain_id;
  			setup.DynamicBase = dynamic_dir;
  			setup.CachePath = dynamic_dir;
  
  			string dynamic_base = setup.DynamicBase;
  			if (CreateDirectory (dynamic_base) && (Environment.GetEnvironmentVariable ("MONO_ASPNET_NODELETE") == null))
  				ClearDynamicBaseDirectory (dynamic_base);
  
  			//
  			// Create app domain
  			//
  			AppDomain appdomain;
  			appdomain = AppDomain.CreateDomain (domain_id, evidence, setup);
  
  			//
  			// Populate with the AppDomain data keys expected, Mono only uses a
  			// few, but third party apps might use others:
  			//
  			appdomain.SetData (".appDomain", "*");
  			int l = physicalDir.Length;
  			if (physicalDir [l - 1] != Path.DirectorySeparatorChar)
  				physicalDir += Path.DirectorySeparatorChar;
  			appdomain.SetData (".appPath", physicalDir);
  
gt: 			appdomain.SetData (".appVPath", virtualDir);