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// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
namespace WixToolset
{
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using WixToolset.Data;
using WixToolset.Extensibility;
public class ExtensionManager : IExtensionManager
{
private List<Assembly> extensionAssemblies = new List<Assembly>();
/// <summary>
/// Loads an assembly from a type description string.
/// </summary>
/// <param name="extension">The assembly type description string.</param>
/// <returns>The loaded assembly. This assembly can be ignored since the extension manager maintains the list of loaded assemblies internally.</returns>
/// <remarks>
/// <paramref name="extension"/> can be in several different forms:
/// <list type="number">
/// <item><term>AssemblyName (MyAssembly, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b17a5c561934e089)</term></item>
/// <item><term>Absolute path to an assembly (C:\MyExtensions\ExtensionAssembly.dll)</term></item>
/// <item><term>Filename of an assembly in the application directory (ExtensionAssembly.dll)</term></item>
/// <item><term>Relative path to an assembly (..\..\MyExtensions\ExtensionAssembly.dll)</term></item>
/// </list>
/// </remarks>
public Assembly Load(string extension)
{
string assemblyName = extension;
Assembly assembly;
// Absolute path to an assembly which means only "load from" will work even though we'd prefer to
// use Assembly.Load (see the documentation for Assembly.LoadFrom why).
if (Path.IsPathRooted(assemblyName))
{
assembly = ExtensionManager.ExtensionLoadFrom(assemblyName);
}
else if (ExtensionManager.TryExtensionLoad(assemblyName, out assembly))
{
// Loaded the assembly by name from the probing path.
}
else if (ExtensionManager.TryExtensionLoad(Path.GetFileNameWithoutExtension(assemblyName), out assembly))
{
// Loaded the assembly by filename alone along the probing path.
}
else // relative path to an assembly
{
// We want to use Assembly.Load when we can because it has some benefits over Assembly.LoadFrom
// (see the documentation for Assembly.LoadFrom). However, it may fail when the path is a relative
// path, so we should try Assembly.LoadFrom one last time. We could have detected a directory
// separator character and used Assembly.LoadFrom directly, but dealing with path canonicalization
// issues is something we don't want to deal with if we don't have to.
assembly = ExtensionManager.ExtensionLoadFrom(assemblyName);
}
this.extensionAssemblies.Add(assembly);
return assembly;
}
/// <summary>
/// Creates extension of specified type from assemblies loaded into the extension manager.
/// </summary>
/// <typeparam name="T">Type of extension to create.</typeparam>
/// <returns>Extensions created of the specified type.</returns>
public IEnumerable<T> Create<T>() where T : class
{
var types = this.extensionAssemblies.SelectMany(a => a.GetTypes().Where(t => !t.IsAbstract && !t.IsInterface && typeof(T).IsAssignableFrom(t)));
return types.Select(t => (T)Activator.CreateInstance(t)).ToList();
}
private static Assembly ExtensionLoadFrom(string assemblyName)
{
try
{
return Assembly.LoadFrom(assemblyName);
}
catch (Exception e)
{
throw new WixException(WixErrors.InvalidExtension(assemblyName, e.Message), e);
}
}
private static bool TryExtensionLoad(string assemblyName, out Assembly assembly)
{
try
{
assembly = Assembly.Load(assemblyName);
return true;
}
catch (IOException innerE)
{
if (innerE is FileLoadException || innerE is FileNotFoundException)
{
assembly = null;
return false;
}
throw new WixException(WixErrors.InvalidExtension(assemblyName, innerE.Message), innerE);
}
catch (Exception e)
{
throw new WixException(WixErrors.InvalidExtension(assemblyName, e.Message), e);
}
}
}
}
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