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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Threading;
using Microsoft.Build.Eventing;
using Microsoft.Build.Framework;
#nullable disable
namespace Microsoft.Build.Shared
{
/// <summary>
/// This class is used to load types from their assemblies.
/// </summary>
internal class TypeLoader
{
#if FEATURE_ASSEMBLYLOADCONTEXT
/// <summary>
/// AssemblyContextLoader used to load DLLs outside of msbuild.exe directory
/// </summary>
private static readonly CoreClrAssemblyLoader s_coreClrAssemblyLoader = new CoreClrAssemblyLoader();
#endif
/// <summary>
/// Cache to keep track of the assemblyLoadInfos based on a given type filter.
/// </summary>
private static ConcurrentDictionary<Func<Type, object, bool>, ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>> s_cacheOfLoadedTypesByFilter = new ConcurrentDictionary<Func<Type, object, bool>, ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>>();
/// <summary>
/// Cache to keep track of the assemblyLoadInfos based on a given type filter for assemblies which are to be loaded for reflectionOnlyLoads.
/// </summary>
private static ConcurrentDictionary<Func<Type, object, bool>, ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>> s_cacheOfReflectionOnlyLoadedTypesByFilter = new ConcurrentDictionary<Func<Type, object, bool>, ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>>();
/// <summary>
/// Type filter for this typeloader
/// </summary>
private Func<Type, object, bool> _isDesiredType;
private static MetadataLoadContext _context;
private static string[] runtimeAssemblies = findRuntimeAssembliesWithMicrosoftBuildFramework();
private static string microsoftBuildFrameworkPath;
// We need to append Microsoft.Build.Framework from next to the executing assembly first to make sure it's loaded before the runtime variant.
private static string[] findRuntimeAssembliesWithMicrosoftBuildFramework()
{
string msbuildDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
microsoftBuildFrameworkPath = Path.Combine(msbuildDirectory, "Microsoft.Build.Framework.dll");
string[] msbuildAssemblies = Directory.GetFiles(msbuildDirectory, "*.dll");
string[] runtimeAssemblies = Directory.GetFiles(RuntimeEnvironment.GetRuntimeDirectory(), "*.dll");
List<string> runtimeAssembliesList = new(runtimeAssemblies);
runtimeAssembliesList.AddRange(msbuildAssemblies);
return runtimeAssembliesList.ToArray();
}
/// <summary>
/// Constructor.
/// </summary>
internal TypeLoader(Func<Type, object, bool> isDesiredType)
{
ErrorUtilities.VerifyThrow(isDesiredType != null, "need a type filter");
_isDesiredType = isDesiredType;
}
/// <summary>
/// Given two type names, looks for a partial match between them. A partial match is considered valid only if it occurs on
/// the right side (tail end) of the name strings, and at the start of a class or namespace name.
/// </summary>
/// <remarks>
/// 1) Matches are case-insensitive.
/// 2) .NET conventions regarding namespaces and nested classes are respected, including escaping of reserved characters.
/// </remarks>
/// <example>
/// "Csc" and "csc" ==> exact match
/// "Microsoft.Build.Tasks.Csc" and "Microsoft.Build.Tasks.Csc" ==> exact match
/// "Microsoft.Build.Tasks.Csc" and "Csc" ==> partial match
/// "Microsoft.Build.Tasks.Csc" and "Tasks.Csc" ==> partial match
/// "MyTasks.ATask+NestedTask" and "NestedTask" ==> partial match
/// "MyTasks.ATask\\+NestedTask" and "NestedTask" ==> partial match
/// "MyTasks.CscTask" and "Csc" ==> no match
/// "MyTasks.MyCsc" and "Csc" ==> no match
/// "MyTasks.ATask\.Csc" and "Csc" ==> no match
/// "MyTasks.ATask\\\.Csc" and "Csc" ==> no match
/// </example>
/// <returns>true, if the type names match exactly or partially; false, if there is no match at all</returns>
internal static bool IsPartialTypeNameMatch(string typeName1, string typeName2)
{
bool isPartialMatch = false;
// if the type names are the same length, a partial match is impossible
if (typeName1.Length != typeName2.Length)
{
string longerTypeName;
string shorterTypeName;
// figure out which type name is longer
if (typeName1.Length > typeName2.Length)
{
longerTypeName = typeName1;
shorterTypeName = typeName2;
}
else
{
longerTypeName = typeName2;
shorterTypeName = typeName1;
}
// if the shorter type name matches the end of the longer one
if (longerTypeName.EndsWith(shorterTypeName, StringComparison.OrdinalIgnoreCase))
{
int matchIndex = longerTypeName.Length - shorterTypeName.Length;
// if the matched sub-string looks like the start of a namespace or class name
if ((longerTypeName[matchIndex - 1] == '.') || (longerTypeName[matchIndex - 1] == '+'))
{
int precedingBackslashes = 0;
// confirm there are zero, or an even number of \'s preceding it...
for (int i = matchIndex - 2; i >= 0; i--)
{
if (longerTypeName[i] == '\\')
{
precedingBackslashes++;
}
else
{
break;
}
}
if ((precedingBackslashes % 2) == 0)
{
isPartialMatch = true;
}
}
}
}
else
{
isPartialMatch = (String.Equals(typeName1, typeName2, StringComparison.OrdinalIgnoreCase));
}
return isPartialMatch;
}
/// <summary>
/// Load an assembly given its AssemblyLoadInfo
/// </summary>
/// <param name="assemblyLoadInfo"></param>
/// <returns></returns>
private static Assembly LoadAssembly(AssemblyLoadInfo assemblyLoadInfo)
{
try
{
if (assemblyLoadInfo.AssemblyName != null)
{
return Assembly.Load(assemblyLoadInfo.AssemblyName);
}
else
{
#if !FEATURE_ASSEMBLYLOADCONTEXT
return Assembly.UnsafeLoadFrom(assemblyLoadInfo.AssemblyFile);
#else
string baseDir = Path.GetDirectoryName(assemblyLoadInfo.AssemblyFile);
s_coreClrAssemblyLoader.AddDependencyLocation(baseDir);
return s_coreClrAssemblyLoader.LoadFromPath(assemblyLoadInfo.AssemblyFile);
#endif
}
}
catch (ArgumentException e)
{
// Assembly.Load() and Assembly.LoadFrom() will throw an ArgumentException if the assembly name is invalid
// convert to a FileNotFoundException because it's more meaningful
// NOTE: don't use ErrorUtilities.VerifyThrowFileExists() here because that will hit the disk again
throw new FileNotFoundException(null, assemblyLoadInfo.AssemblyLocation, e);
}
}
private static Assembly LoadAssemblyUsingMetadataLoadContext(AssemblyLoadInfo assemblyLoadInfo)
{
string path = assemblyLoadInfo.AssemblyFile;
string[] localAssemblies = Directory.GetFiles(Path.GetDirectoryName(path), "*.dll");
// Deduplicate between MSBuild assemblies and task dependencies.
Dictionary<string, string> assembliesDictionary = new(localAssemblies.Length + runtimeAssemblies.Length);
foreach (string localPath in localAssemblies)
{
assembliesDictionary.Add(Path.GetFileName(localPath), localPath);
}
foreach (string runtimeAssembly in runtimeAssemblies)
{
assembliesDictionary[Path.GetFileName(runtimeAssembly)] = runtimeAssembly;
}
_context = new(new PathAssemblyResolver(assembliesDictionary.Values));
return _context.LoadFromAssemblyPath(path);
}
/// <summary>
/// Loads the specified type if it exists in the given assembly. If the type name is fully qualified, then a match (if
/// any) is unambiguous; otherwise, if there are multiple types with the same name in different namespaces, the first type
/// found will be returned.
/// </summary>
internal LoadedType Load(
string typeName,
AssemblyLoadInfo assembly,
bool useTaskHost = false)
{
return GetLoadedType(s_cacheOfLoadedTypesByFilter, typeName, assembly, useTaskHost);
}
/// <summary>
/// Loads the specified type if it exists in the given assembly. If the type name is fully qualified, then a match (if
/// any) is unambiguous; otherwise, if there are multiple types with the same name in different namespaces, the first type
/// found will be returned.
/// </summary>
/// <returns>The loaded type, or null if the type was not found.</returns>
internal LoadedType ReflectionOnlyLoad(
string typeName,
AssemblyLoadInfo assembly)
{
return GetLoadedType(s_cacheOfReflectionOnlyLoadedTypesByFilter, typeName, assembly, useTaskHost: false);
}
/// <summary>
/// Loads the specified type if it exists in the given assembly. If the type name is fully qualified, then a match (if
/// any) is unambiguous; otherwise, if there are multiple types with the same name in different namespaces, the first type
/// found will be returned.
/// </summary>
private LoadedType GetLoadedType(ConcurrentDictionary<Func<Type, object, bool>, ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>> cache, string typeName, AssemblyLoadInfo assembly, bool useTaskHost)
{
// A given type filter have been used on a number of assemblies, Based on the type filter we will get another dictionary which
// will map a specific AssemblyLoadInfo to a AssemblyInfoToLoadedTypes class which knows how to find a typeName in a given assembly.
ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes> loadInfoToType =
cache.GetOrAdd(_isDesiredType, (_) => new ConcurrentDictionary<AssemblyLoadInfo, AssemblyInfoToLoadedTypes>());
// Get an object which is able to take a typename and determine if it is in the assembly pointed to by the AssemblyInfo.
AssemblyInfoToLoadedTypes typeNameToType =
loadInfoToType.GetOrAdd(assembly, (_) => new AssemblyInfoToLoadedTypes(_isDesiredType, _));
return typeNameToType.GetLoadedTypeByTypeName(typeName, useTaskHost);
}
/// <summary>
/// Given a type filter and an asssemblyInfo object keep track of what types in a given assembly which match the type filter.
/// Also, use this information to determine if a given TypeName is in the assembly which is pointed to by the AssemblyLoadInfo object.
///
/// This type represents a combination of a type filter and an assemblyInfo object.
/// </summary>
[DebuggerDisplay("Types in {_assemblyLoadInfo} matching {_isDesiredType}")]
private class AssemblyInfoToLoadedTypes
{
/// <summary>
/// Lock to prevent two threads from using this object at the same time.
/// Since we fill up internal structures with what is in the assembly
/// </summary>
private readonly Object _lockObject = new Object();
/// <summary>
/// Type filter to pick the correct types out of an assembly
/// </summary>
private Func<Type, object, bool> _isDesiredType;
/// <summary>
/// Assembly load information so we can load an assembly
/// </summary>
private AssemblyLoadInfo _assemblyLoadInfo;
/// <summary>
/// What is the type for the given type name, this may be null if the typeName does not map to a type.
/// </summary>
private ConcurrentDictionary<string, Type> _typeNameToType;
/// <summary>
/// List of public types in the assembly which match the type filter and their corresponding types
/// </summary>
private Dictionary<string, Type> _publicTypeNameToType;
private ConcurrentDictionary<string, LoadedType> _publicTypeNameToLoadedType;
/// <summary>
/// Have we scanned the public types for this assembly yet.
/// </summary>
private long _haveScannedPublicTypes;
/// <summary>
/// Assembly, if any, that we loaded for this type.
/// We use this information to set the LoadedType.LoadedAssembly so that this object can be used
/// to help created AppDomains to resolve those that it could not load successfully
/// </summary>
private Assembly _loadedAssembly;
/// <summary>
/// Given a type filter, and an assembly to load the type information from determine if a given type name is in the assembly or not.
/// </summary>
internal AssemblyInfoToLoadedTypes(Func<Type, object, bool> typeFilter, AssemblyLoadInfo loadInfo)
{
ErrorUtilities.VerifyThrowArgumentNull(typeFilter, "typefilter");
ErrorUtilities.VerifyThrowArgumentNull(loadInfo, nameof(loadInfo));
_isDesiredType = typeFilter;
_assemblyLoadInfo = loadInfo;
_typeNameToType = new(StringComparer.OrdinalIgnoreCase);
_publicTypeNameToType = new Dictionary<string, Type>(StringComparer.OrdinalIgnoreCase);
_publicTypeNameToLoadedType = new(StringComparer.OrdinalIgnoreCase);
}
/// <summary>
/// Determine if a given type name is in the assembly or not. Return null if the type is not in the assembly
/// </summary>
internal LoadedType GetLoadedTypeByTypeName(string typeName, bool useTaskHost)
{
ErrorUtilities.VerifyThrowArgumentNull(typeName, nameof(typeName));
if (useTaskHost && _assemblyLoadInfo.AssemblyFile is not null)
{
return GetLoadedTypeFromTypeNameUsingMetadataLoadContext(typeName);
}
// Only one thread should be doing operations on this instance of the object at a time.
Type type = _typeNameToType.GetOrAdd(typeName, (key) =>
{
if ((_assemblyLoadInfo.AssemblyName != null) && (typeName.Length > 0))
{
try
{
// try to load the type using its assembly qualified name
Type t2 = Type.GetType(typeName + "," + _assemblyLoadInfo.AssemblyName, false /* don't throw on error */, true /* case-insensitive */);
if (t2 != null)
{
return !_isDesiredType(t2, null) ? null : t2;
}
}
catch (ArgumentException)
{
// Type.GetType() will throw this exception if the type name is invalid -- but we have no idea if it's the
// type or the assembly name that's the problem -- so just ignore the exception, because we're going to
// check the existence/validity of the assembly and type respectively, below anyway
}
}
if (Interlocked.Read(ref _haveScannedPublicTypes) == 0)
{
lock (_lockObject)
{
if (Interlocked.Read(ref _haveScannedPublicTypes) == 0)
{
ScanAssemblyForPublicTypes();
Interlocked.Exchange(ref _haveScannedPublicTypes, ~0);
}
}
}
foreach (KeyValuePair<string, Type> desiredTypeInAssembly in _publicTypeNameToType)
{
// if type matches partially on its name
if (typeName.Length == 0 || TypeLoader.IsPartialTypeNameMatch(desiredTypeInAssembly.Key, typeName))
{
return desiredTypeInAssembly.Value;
}
}
return null;
});
return type != null ? new LoadedType(type, _assemblyLoadInfo, _loadedAssembly ?? type.Assembly, typeof(ITaskItem), loadedViaMetadataLoadContext: false) : null;
}
private LoadedType GetLoadedTypeFromTypeNameUsingMetadataLoadContext(string typeName)
{
return _publicTypeNameToLoadedType.GetOrAdd(typeName, typeName =>
{
MSBuildEventSource.Log.LoadAssemblyAndFindTypeStart();
Assembly loadedAssembly = LoadAssemblyUsingMetadataLoadContext(_assemblyLoadInfo);
int numberOfTypesSearched = 0;
foreach (Type publicType in loadedAssembly.GetExportedTypes())
{
numberOfTypesSearched++;
if (_isDesiredType(publicType, null) && (typeName.Length == 0 || TypeLoader.IsPartialTypeNameMatch(publicType.FullName, typeName)))
{
MSBuildEventSource.Log.CreateLoadedTypeStart(loadedAssembly.FullName);
LoadedType loadedType = new(publicType, _assemblyLoadInfo, loadedAssembly, _context.LoadFromAssemblyPath(microsoftBuildFrameworkPath).GetType(typeof(ITaskItem).FullName), loadedViaMetadataLoadContext: true);
_context?.Dispose();
_context = null;
MSBuildEventSource.Log.CreateLoadedTypeStop(loadedAssembly.FullName);
return loadedType;
}
}
MSBuildEventSource.Log.LoadAssemblyAndFindTypeStop(_assemblyLoadInfo.AssemblyFile, numberOfTypesSearched);
return null;
});
}
/// <summary>
/// Scan the assembly pointed to by the assemblyLoadInfo for public types. We will use these public types to do partial name matching on
/// to find tasks, loggers, and task factories.
/// </summary>
private void ScanAssemblyForPublicTypes()
{
// we need to search the assembly for the type...
_loadedAssembly = LoadAssembly(_assemblyLoadInfo);
// only look at public types
Type[] allPublicTypesInAssembly = _loadedAssembly.GetExportedTypes();
foreach (Type publicType in allPublicTypesInAssembly)
{
if (_isDesiredType(publicType, null))
{
_publicTypeNameToType.Add(publicType.FullName, publicType);
}
}
}
}
}
}
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