systeminfo.cs

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#region Copyright & License
//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.Reflection;
using System.Text;
using System.IO;
using System.Runtime.InteropServices;

namespace log4net.Util
{
	/// <summary>
	/// Utility class for system specific information.
	/// </summary>
	/// <remarks>
	/// <para>
	/// Utility class of static methods for system specific information.
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	/// <author>Gert Driesen</author>
	/// <author>Alexey Solofnenko</author>
	public sealed class SystemInfo
	{
		#region Private Instance Constructors

		/// <summary>
		/// Private constructor to prevent instances.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Only static methods are exposed from this type.
		/// </para>
		/// </remarks>
		private SystemInfo() 
		{
		}

		#endregion Private Instance Constructors

		#region Public Static Properties

		/// <summary>
		/// Gets the system dependent line terminator.
		/// </summary>
		/// <value>
		/// The system dependent line terminator.
		/// </value>
		/// <remarks>
		/// <para>
		/// Gets the system dependent line terminator.
		/// </para>
		/// </remarks>
		public static string NewLine
		{
			get
			{
#if NETCF
				return "\r\n";
#else
				return System.Environment.NewLine;
#endif
			}
		}

		/// <summary>
		/// Gets the base directory for this <see cref="AppDomain"/>.
		/// </summary>
		/// <value>The base directory path for the current <see cref="AppDomain"/>.</value>
		/// <remarks>
		/// <para>
		/// Gets the base directory for this <see cref="AppDomain"/>.
		/// </para>
		/// <para>
		/// The value returned may be either a local file path or a URI.
		/// </para>
		/// </remarks>
		public static string ApplicationBaseDirectory
		{
			get 
			{
#if NETCF
				return System.IO.Path.GetDirectoryName(SystemInfo.EntryAssemblyLocation) + System.IO.Path.DirectorySeparatorChar;
#else
				return AppDomain.CurrentDomain.BaseDirectory;
#endif
			}
		}

		/// <summary>
		/// Gets the path to the configuration file for the current <see cref="AppDomain"/>.
		/// </summary>
		/// <value>The path to the configuration file for the current <see cref="AppDomain"/>.</value>
		/// <remarks>
		/// <para>
		/// The .NET Compact Framework 1.0 does not have a concept of a configuration
		/// file. For this runtime, we use the entry assembly location as the root for
		/// the configuration file name.
		/// </para>
		/// <para>
		/// The value returned may be either a local file path or a URI.
		/// </para>
		/// </remarks>
		public static string ConfigurationFileLocation
		{
			get 
			{
#if NETCF
				return SystemInfo.EntryAssemblyLocation+".config";
#else
				return System.AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
#endif
			}
		}

		/// <summary>
		/// Gets the path to the file that first executed in the current <see cref="AppDomain"/>.
		/// </summary>
		/// <value>The path to the entry assembly.</value>
		/// <remarks>
		/// <para>
		/// Gets the path to the file that first executed in the current <see cref="AppDomain"/>.
		/// </para>
		/// </remarks>
		public static string EntryAssemblyLocation
		{
			get 
			{
#if NETCF
				return SystemInfo.NativeEntryAssemblyLocation;
#else
				return System.Reflection.Assembly.GetEntryAssembly().Location;
#endif
			}
		}

		/// <summary>
		/// Gets the ID of the current thread.
		/// </summary>
		/// <value>The ID of the current thread.</value>
		/// <remarks>
		/// <para>
		/// On the .NET framework, the <c>AppDomain.GetCurrentThreadId</c> method
		/// is used to obtain the thread ID for the current thread. This is the 
		/// operating system ID for the thread.
		/// </para>
		/// <para>
		/// On the .NET Compact Framework 1.0 it is not possible to get the 
		/// operating system thread ID for the current thread. The native method 
		/// <c>GetCurrentThreadId</c> is implemented inline in a header file
		/// and cannot be called.
		/// </para>
		/// </remarks>
		public static int CurrentThreadId
		{
			get 
			{
#if NETCF
				return System.Threading.Thread.CurrentThread.GetHashCode();
#else
				return AppDomain.GetCurrentThreadId();
#endif
			}
		}

		/// <summary>
		/// Get the host name or machine name for the current machine
		/// </summary>
		/// <value>
		/// The hostname or machine name
		/// </value>
		/// <remarks>
		/// <para>
		/// Get the host name or machine name for the current machine
		/// </para>
		/// <para>
		/// The host name (<see cref="System.Net.Dns.GetHostName"/>) or
		/// the machine name (<c>Environment.MachineName</c>) for
		/// the current machine, or if neither of these are available
		/// then <c>NOT AVAILABLE</c> is returned.
		/// </para>
		/// </remarks>
		public static string HostName
		{
			get
			{
				if (s_hostName == null)
				{

					// Get the DNS host name of the current machine
					try
					{
						// Lookup the host name
						s_hostName = System.Net.Dns.GetHostName();
					}
					catch(System.Net.Sockets.SocketException)
					{
					}
					catch(System.Security.SecurityException)
					{
						// We may get a security exception looking up the hostname
						// You must have Unrestricted DnsPermission to access resource
					}

					// Get the NETBIOS machine name of the current machine
					if (s_hostName == null || s_hostName.Length == 0)
					{
						try
						{
#if (!SSCLI && !NETCF)
							s_hostName = Environment.MachineName;
#endif
						}
						catch(InvalidOperationException)
						{
						}
						catch(System.Security.SecurityException)
						{
							// We may get a security exception looking up the machine name
							// You must have Unrestricted EnvironmentPermission to access resource
						}
					}

					// Couldn't find a value
					if (s_hostName == null || s_hostName.Length == 0)
					{
						s_hostName = "NOT AVAILABLE";
					}
				}
				return s_hostName;
			}
		}

		/// <summary>
		/// Get this application's friendly name
		/// </summary>
		/// <value>
		/// The friendly name of this application as a string
		/// </value>
		/// <remarks>
		/// <para>
		/// If available the name of the application is retrieved from
		/// the <c>AppDomain</c> using <c>AppDomain.CurrentDomain.FriendlyName</c>.
		/// </para>
		/// <para>
		/// Otherwise the file name of the entry assembly is used.
		/// </para>
		/// </remarks>
		public static string ApplicationFriendlyName
		{
			get
			{
				if (s_appFriendlyName == null)
				{
					try
					{
#if !NETCF
						s_appFriendlyName = AppDomain.CurrentDomain.FriendlyName;
#endif
					}
					catch(System.Security.SecurityException)
					{
						// This security exception will occur if the caller does not have 
						// some undefined set of SecurityPermission flags.
						LogLog.Debug("SystemInfo: Security exception while trying to get current domain friendly name. Error Ignored.");
					}

					if (s_appFriendlyName == null || s_appFriendlyName.Length == 0)
					{
						try
						{
							string assemblyLocation = SystemInfo.EntryAssemblyLocation;
							s_appFriendlyName = System.IO.Path.GetFileName(assemblyLocation);
						}
						catch(System.Security.SecurityException)
						{
							// Caller needs path discovery permission
						}
					}

					if (s_appFriendlyName == null || s_appFriendlyName.Length == 0)
					{
						s_appFriendlyName = "NOT AVAILABLE";
					}
				}
				return s_appFriendlyName;
			}
		}

		private static DateTime s_processStartTime = DateTime.MinValue;

		/// <summary>
		/// Get the start time for the current process.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Tries to get the start time for the current process.
		/// Failing that it returns the time of the first call to
		/// this property.
		/// </para>
		/// <para>
		/// Note that AppDomains may be loaded and unloaded within the
		/// same process without the process terminating and therefore
		/// without the process start time being reset.
		/// </para>
		/// </remarks>
		public static DateTime ProcessStartTime
		{
			get
			{
				if (s_processStartTime == DateTime.MinValue)
				{
#if (NETCF || SSCLI)
					// NETCF does not have the System.Diagnostics.Process class
					// SSCLI does not support StartTime property in System.Diagnostics.Process

					// Use the time of the first call as the start time
					s_processStartTime = DateTime.Now;
#else
					try
					{
						s_processStartTime = System.Diagnostics.Process.GetCurrentProcess().StartTime;
					}
					catch
					{
						// Unable to get the start time, use now as the start time
						s_processStartTime = DateTime.Now;
					}
#endif
				}
				return s_processStartTime;
			}
		}

		#endregion Public Static Properties

		#region Public Static Methods

		/// <summary>
		/// Gets the assembly location path for the specified assembly.
		/// </summary>
		/// <param name="myAssembly">The assembly to get the location for.</param>
		/// <returns>The location of the assembly.</returns>
		/// <remarks>
		/// <para>
		/// This method does not guarantee to return the correct path
		/// to the assembly. If only tries to give an indication as to
		/// where the assembly was loaded from.
		/// </para>
		/// </remarks>
		public static string AssemblyLocationInfo(Assembly myAssembly)
		{
#if NETCF
			return "Not supported on Microsoft .NET Compact Framework";
#else
			if (myAssembly.GlobalAssemblyCache)
			{
				return "Global Assembly Cache";
			}
			else
			{
				try
				{
					// This call requires FileIOPermission for access to the path
					// if we don't have permission then we just ignore it and
					// carry on.
					return myAssembly.Location;
				}
				catch(System.Security.SecurityException)
				{
					return "Location Permission Denied";
				}
			}
#endif
		}

		/// <summary>
		/// Gets the fully qualified name of the <see cref="Type" />, including 
		/// the name of the assembly from which the <see cref="Type" /> was 
		/// loaded.
		/// </summary>
		/// <param name="type">The <see cref="Type" /> to get the fully qualified name for.</param>
		/// <returns>The fully qualified name for the <see cref="Type" />.</returns>
		/// <remarks>
		/// <para>
		/// This is equivalent to the <c>Type.AssemblyQualifiedName</c> property,
		/// but this method works on the .NET Compact Framework 1.0 as well as
		/// the full .NET runtime.
		/// </para>
		/// </remarks>
		public static string AssemblyQualifiedName(Type type)
		{
			return type.FullName + ", " + type.Assembly.FullName;
		}

		/// <summary>
		/// Gets the short name of the <see cref="Assembly" />.
		/// </summary>
		/// <param name="myAssembly">The <see cref="Assembly" /> to get the name for.</param>
		/// <returns>The short name of the <see cref="Assembly" />.</returns>
		/// <remarks>
		/// <para>
		/// The short name of the assembly is the <see cref="Assembly.FullName" /> 
		/// without the version, culture, or public key. i.e. it is just the 
		/// assembly's file name without the extension.
		/// </para>
		/// <para>
		/// Use this rather than <c>Assembly.GetName().Name</c> because that
		/// is not available on the Compact Framework.
		/// </para>
		/// <para>
		/// Because of a FileIOPermission security demand we cannot do
		/// the obvious Assembly.GetName().Name. We are allowed to get
		/// the <see cref="Assembly.FullName" /> of the assembly so we 
		/// start from there and strip out just the assembly name.
		/// </para>
		/// </remarks>
		public static string AssemblyShortName(Assembly myAssembly)
		{
			string name = myAssembly.FullName;
			int offset = name.IndexOf(',');
			if (offset > 0)
			{
				name = name.Substring(0, offset);
			}
			return name.Trim();

			// TODO: Do we need to unescape the assembly name string? 
			// Doc says '\' is an escape char but has this already been 
			// done by the string loader?
		}

		/// <summary>
		/// Gets the file name portion of the <see cref="Assembly" />, including the extension.
		/// </summary>
		/// <param name="myAssembly">The <see cref="Assembly" /> to get the file name for.</param>
		/// <returns>The file name of the assembly.</returns>
		/// <remarks>
		/// <para>
		/// Gets the file name portion of the <see cref="Assembly" />, including the extension.
		/// </para>
		/// </remarks>
		public static string AssemblyFileName(Assembly myAssembly)
		{
#if NETCF
			// This is not very good because it assumes that only
			// the entry assembly can be an EXE. In fact multiple
			// EXEs can be loaded in to a process.

			string assemblyShortName = SystemInfo.AssemblyShortName(myAssembly);
			string entryAssemblyShortName = System.IO.Path.GetFileNameWithoutExtension(SystemInfo.EntryAssemblyLocation);

			if (string.Compare(assemblyShortName, entryAssemblyShortName, true) == 0)
			{
				// assembly is entry assembly
				return assemblyShortName + ".exe";
			}
			else
			{
				// assembly is not entry assembly
				return assemblyShortName + ".dll";
			}
#else
			return System.IO.Path.GetFileName(myAssembly.Location);
#endif
		}

		/// <summary>
		/// Loads the type specified in the type string.
		/// </summary>
		/// <param name="relativeType">A sibling type to use to load the type.</param>
		/// <param name="typeName">The name of the type to load.</param>
		/// <param name="throwOnError">Flag set to <c>true</c> to throw an exception if the type cannot be loaded.</param>
		/// <param name="ignoreCase"><c>true</c> to ignore the case of the type name; otherwise, <c>false</c></param>
		/// <returns>The type loaded or <c>null</c> if it could not be loaded.</returns>
		/// <remarks>
		/// <para>
		/// If the type name is fully qualified, i.e. if contains an assembly name in 
		/// the type name, the type will be loaded from the system using 
		/// <see cref="Type.GetType(string,bool)"/>.
		/// </para>
		/// <para>
		/// If the type name is not fully qualified, it will be loaded from the assembly
		/// containing the specified relative type. If the type is not found in the assembly 
		/// then all the loaded assemblies will be searched for the type.
		/// </para>
		/// </remarks>