CimDSCParser.cs

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Management.Automation;
using System.Management.Automation.Language;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Security;
using System.Text;

using Microsoft.Management.Infrastructure;
using Microsoft.Management.Infrastructure.Generic;
using Microsoft.Management.Infrastructure.Serialization;
using Microsoft.PowerShell.Commands;

namespace Microsoft.PowerShell.DesiredStateConfiguration.Internal
{
    /// <summary>
    /// </summary>
    [SuppressMessage("Microsoft.MSInternal", "CA903:InternalNamespaceShouldNotContainPublicTypes",
        Justification = "Needed Internal use only")]
    public static class DscRemoteOperationsClass
    {
        /// <summary>
        /// Convert Cim Instance representing Resource desired state to Powershell Class Object.
        /// </summary>
        public static object ConvertCimInstanceToObject(Type targetType, CimInstance instance, string moduleName)
        {
            var className = instance.CimClass.CimSystemProperties.ClassName;
            object targetObject = null;
            string errorMessage;

            using (System.Management.Automation.PowerShell powerShell = System.Management.Automation.PowerShell.Create(RunspaceMode.CurrentRunspace))
            {
                const string script = "param($targetType,$moduleName) & (Microsoft.PowerShell.Core\\Get-Module $moduleName) { New-Object $targetType } ";

                powerShell.AddScript(script);
                powerShell.AddArgument(targetType);
                powerShell.AddArgument(moduleName);

                Collection<PSObject> psExecutionResult = powerShell.Invoke();
                if (psExecutionResult.Count == 1)
                {
                    targetObject = psExecutionResult[0].BaseObject;
                }
                else
                {
                    Exception innerException = null;
                    if (powerShell.Streams.Error != null && powerShell.Streams.Error.Count > 0)
                    {
                        innerException = powerShell.Streams.Error[0].Exception;
                    }

                    errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InstantiatePSClassObjectFailed, className);
                    var invalidOperationException = new InvalidOperationException(errorMessage, innerException);
                    throw invalidOperationException;
                }
            }

            foreach (var property in instance.CimInstanceProperties)
            {
                if (property.Value != null)
                {
                    MemberInfo[] memberInfo = targetType.GetMember(property.Name, BindingFlags.Public | BindingFlags.Instance);

                    // verify property exists in corresponding class type
                    if (memberInfo == null
                        || memberInfo.Length > 1
                        || (memberInfo[0] is not PropertyInfo && memberInfo[0] is not FieldInfo))
                    {
                        errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.PropertyNotDeclaredInPSClass, new object[] { property.Name, className });
                        var invalidOperationException = new InvalidOperationException(errorMessage);
                        throw invalidOperationException;
                    }

                    var member = memberInfo[0];
                    var memberType = (member is FieldInfo)
                        ? ((FieldInfo)member).FieldType
                        : ((PropertyInfo)member).PropertyType;

                    object targetValue = null;
                    switch (property.CimType)
                    {
                        case CimType.Instance:
                            {
                                var cimPropertyInstance = property.Value as CimInstance;
                                if (cimPropertyInstance != null &&
                                    cimPropertyInstance.CimClass != null &&
                                    cimPropertyInstance.CimClass.CimSystemProperties != null &&
                                    string.Equals(
                                        cimPropertyInstance.CimClass.CimSystemProperties.ClassName,
                                        "MSFT_Credential", StringComparison.OrdinalIgnoreCase))
                                {
                                    targetValue = ConvertCimInstancePsCredential(moduleName, cimPropertyInstance);
                                }
                                else
                                {
                                    targetValue = ConvertCimInstanceToObject(memberType, cimPropertyInstance, moduleName);
                                }

                                if (targetValue == null)
                                {
                                    return null;
                                }
                            }

                            break;
                        case CimType.InstanceArray:
                            {
                                if (memberType == typeof(Hashtable))
                                {
                                    targetValue = ConvertCimInstanceHashtable(moduleName, (CimInstance[])property.Value);
                                }
                                else
                                {
                                    var instanceArray = (CimInstance[])property.Value;
                                    if (!memberType.IsArray)
                                    {
                                        errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.ExpectArrayTypeOfPropertyInPSClass, new object[] { property.Name, className });
                                        var invalidOperationException = new InvalidOperationException(errorMessage);
                                        throw invalidOperationException;
                                    }

                                    var elementType = memberType.GetElementType();
                                    var targetArray = Array.CreateInstance(elementType, instanceArray.Length);
                                    for (int i = 0; i < instanceArray.Length; i++)
                                    {
                                        var obj = ConvertCimInstanceToObject(elementType, instanceArray[i], moduleName);
                                        if (obj == null)
                                        {
                                            return null;
                                        }

                                        targetArray.SetValue(obj, i);
                                    }

                                    targetValue = targetArray;
                                }
                            }

                            break;
                        default:
                            targetValue = LanguagePrimitives.ConvertTo(property.Value, memberType, CultureInfo.InvariantCulture);
                            break;
                    }

                    if (targetValue == null)
                    {
                        errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.ConvertCimPropertyToObjectPropertyFailed, new object[] { property.Name, className });
                        var invalidOperationException = new InvalidOperationException(errorMessage);
                        throw invalidOperationException;
                    }

                    if (member is FieldInfo)
                    {
                        ((FieldInfo)member).SetValue(targetObject, targetValue);
                    }

                    if (member is PropertyInfo)
                    {
                        ((PropertyInfo)member).SetValue(targetObject, targetValue);
                    }
                }
            }

            return targetObject;
        }

        /// <summary>
        /// Convert hashtable from Ciminstance to hashtable primitive type.
        /// </summary>
        /// <param name="providerName"></param>
        /// <param name="arrayInstance"></param>
        /// <returns></returns>
        private static object ConvertCimInstanceHashtable(string providerName, CimInstance[] arrayInstance)
        {
            var result = new Hashtable();
            string errorMessage;

            try
            {
                foreach (var keyValuePair in arrayInstance)
                {
                    var key = keyValuePair.CimInstanceProperties["Key"];
                    var value = keyValuePair.CimInstanceProperties["Value"];

                    if (key == null || value == null)
                    {
                        errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidHashtable, providerName);
                        var invalidOperationException = new InvalidOperationException(errorMessage);
                        throw invalidOperationException;
                    }

                    result.Add(LanguagePrimitives.ConvertTo<string>(key.Value), LanguagePrimitives.ConvertTo<string>(value.Value));
                }
            }
            catch (Exception exception)
            {
                errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidHashtable, providerName);
                var invalidOperationException = new InvalidOperationException(errorMessage, exception);
                throw invalidOperationException;
            }

            return result;
        }
        /// <summary>
        /// Convert CIM instance to PS Credential.
        /// </summary>
        /// <param name="providerName"></param>
        /// <param name="propertyInstance"></param>
        /// <returns></returns>
        private static object ConvertCimInstancePsCredential(string providerName, CimInstance propertyInstance)
        {
            string errorMessage;
            string userName;
            string plainPassWord;

            try
            {
                userName = propertyInstance.CimInstanceProperties["UserName"].Value as string;
                if (string.IsNullOrEmpty(userName))
                {
                    errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidUserName, providerName);
                    var invalidOperationException = new InvalidOperationException(errorMessage);
                    throw invalidOperationException;
                }
            }
            catch (CimException exception)
            {
                errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidUserName, providerName);
                var invalidOperationException = new InvalidOperationException(errorMessage, exception);
                throw invalidOperationException;
            }

            try
            {
                plainPassWord = propertyInstance.CimInstanceProperties["PassWord"].Value as string;

                // In future we might receive password in an encrypted format. Make sure we add
                // the decryption login in this method.
                if (string.IsNullOrEmpty(plainPassWord))
                {
                    errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidPassword, providerName);
                    var invalidOperationException = new InvalidOperationException(errorMessage);
                    throw invalidOperationException;
                }
            }
            catch (CimException exception)
            {
                errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.InvalidPassword, providerName);
                var invalidOperationException = new InvalidOperationException(errorMessage, exception);
                throw invalidOperationException;
            }

            // Extract the password into a SecureString.
            var password = new SecureString();
            foreach (char t in plainPassWord)
            {
                password.AppendChar(t);
            }

            password.MakeReadOnly();
            return new PSCredential(userName, password);
        }
    }
}

namespace Microsoft.PowerShell.DesiredStateConfiguration
{
    /// <summary>
    /// To make it easier to specify -ConfigurationData parameter, we add an ArgumentTransformationAttribute here.
    /// When the input data is of type string and is valid path to a file that can be converted to hashtable, we do
    /// the conversion and return the converted value. Otherwise, we just return the input data.
    /// </summary>
    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property | AttributeTargets.Parameter, AllowMultiple = false)]
    public sealed class ArgumentToConfigurationDataTransformationAttribute : ArgumentTransformationAttribute
    {
        /// <summary>
        /// Convert a file of ConfigurationData into a hashtable.
        /// </summary>
        /// <param name="engineIntrinsics"></param>
        /// <param name="inputData"></param>
        /// <returns></returns>
        public override object Transform(EngineIntrinsics engineIntrinsics, object inputData)
        {
            var configDataPath = inputData as string;
            if (string.IsNullOrEmpty(configDataPath))
            {
                return inputData;
            }

            if (engineIntrinsics == null)
            {
                throw PSTraceSource.NewArgumentNullException(nameof(engineIntrinsics));
            }

            return PsUtils.EvaluatePowerShellDataFileAsModuleManifest(
                      "ConfigurationData",
                      configDataPath,
                      engineIntrinsics.SessionState.Internal.ExecutionContext,
                      skipPathValidation: false);
        }
    }

    /// <summary>
    /// <para>
    /// Represents a communication channel to a CIM server.
    /// </para>
    /// <para>
    /// This is the main entry point of the Microsoft.Management.Infrastructure API.
    /// All CIM operations are represented as methods of this class.
    /// </para>
    /// </summary>
    internal class CimDSCParser
    {
        private CimMofDeserializer _deserializer;
        private CimMofDeserializer.OnClassNeeded _onClassNeeded;

        /// <summary>
        /// </summary>
        internal CimDSCParser(CimMofDeserializer.OnClassNeeded onClassNeeded)
        {
            _deserializer = CimMofDeserializer.Create();
            _onClassNeeded = onClassNeeded;
        }

        /// <summary>
        /// </summary>
        internal CimDSCParser(CimMofDeserializer.OnClassNeeded onClassNeeded, Microsoft.Management.Infrastructure.Serialization.MofDeserializerSchemaValidationOption validationOptions)
        {
            _deserializer = CimMofDeserializer.Create();
            _deserializer.SchemaValidationOption = validationOptions;
            _onClassNeeded = onClassNeeded;
        }

        /// <summary>
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        [SuppressMessage("Microsoft.Design", "CA1045:DoNotPassTypesByReference", MessageId = "3#", Justification = "Have to return 2 things.  Wrapping those 2 things in a class will result in a more, not less complexity")]
        internal List<CimInstance> ParseInstanceMof(string filePath)
        {
            uint offset = 0;
            var buffer = GetFileContent(filePath);
            try
            {
                var result = new List<CimInstance>(_deserializer.DeserializeInstances(buffer, ref offset, _onClassNeeded, null));
                return result;
            }
            catch (CimException exception)
            {
                PSInvalidOperationException e = PSTraceSource.NewInvalidOperationException(
                    exception, ParserStrings.CimDeserializationError, filePath);

                e.SetErrorId("CimDeserializationError");
                throw e;
            }
        }

        /// <summary>
        /// Read file content to byte array.
        /// </summary>
        /// <param name="fullFilePath"></param>
        /// <returns></returns>
        internal static byte[] GetFileContent(string fullFilePath)
        {
            if (string.IsNullOrEmpty(fullFilePath))
            {
                throw PSTraceSource.NewArgumentNullException(nameof(fullFilePath));
            }

            if (!File.Exists(fullFilePath))
            {
                var errorMessage = string.Format(CultureInfo.CurrentCulture, ParserStrings.FileNotFound, fullFilePath);
                throw PSTraceSource.NewArgumentException(nameof(fullFilePath), errorMessage);
            }

            using (FileStream fs = File.OpenRead(fullFilePath))
            {
                var bytes = new byte[fs.Length];
                fs.Read(bytes, 0, Convert.ToInt32(fs.Length));
                return bytes;
            }
        }

        internal List<CimClass> ParseSchemaMofFileBuffer(string mof)
        {
            uint offset = 0;
#if UNIX
            // OMI only supports UTF-8 without BOM
            var encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
#else
            // This is what we traditionally use with Windows
            // DSC asked to keep it UTF-32 for Windows
            var encoding = new UnicodeEncoding();
#endif

            var buffer = encoding.GetBytes(mof);

            var result = new List<CimClass>(_deserializer.DeserializeClasses(buffer, ref offset, null, null, null, _onClassNeeded, null));
            return result;
        }

        /// <summary>
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        [SuppressMessage("Microsoft.Design", "CA1045:DoNotPassTypesByReference", MessageId = "3#", Justification = "Have to return 2 things.  Wrapping those 2 things in a class will result in a more, not less complexity")]
        internal List<CimClass> ParseSchemaMof(string filePath)
        {
            uint offset = 0;
            var buffer = GetFileContent(filePath);
            try
            {
                string fileNameDefiningClass = Path.GetFileNameWithoutExtension(filePath);
                int dotIndex = fileNameDefiningClass.IndexOf('.');
                if (dotIndex != -1)
                {
                    fileNameDefiningClass = fileNameDefiningClass.Substring(0, dotIndex);
                }

                var result = new List<CimClass>(_deserializer.DeserializeClasses(buffer, ref offset, null, null, null, _onClassNeeded, null));
                foreach (CimClass c in result)
                {
                    string superClassName = c.CimSuperClassName;
                    string className = c.CimSystemProperties.ClassName;
                    if ((superClassName != null) && (superClassName.Equals("OMI_BaseResource", StringComparison.OrdinalIgnoreCase)))
                    {
                        // Get the name of the file without schema.mof extension
                        if (!(className.Equals(fileNameDefiningClass, StringComparison.OrdinalIgnoreCase)))
                        {
                            PSInvalidOperationException e = PSTraceSource.NewInvalidOperationException(
                                ParserStrings.ClassNameNotSameAsDefiningFile, className, fileNameDefiningClass);
                            throw e;
                        }
                    }
                }

                return result;
            }
            catch (CimException exception)
            {
                PSInvalidOperationException e = PSTraceSource.NewInvalidOperationException(
                    exception, ParserStrings.CimDeserializationError, filePath);

                e.SetErrorId("CimDeserializationError");
                throw e;
            }
        }

        /// <summary>
        /// Make sure that the instance conforms to the schema.
        /// </summary>
        /// <param name="classText"></param>
        internal void ValidateInstanceText(string classText)
        {
            uint offset = 0;
            byte[] bytes = null;

            if (Platform.IsLinux || Platform.IsMacOS)
            {
                bytes = System.Text.Encoding.UTF8.GetBytes(classText);
            }
            else
            {
                bytes = System.Text.Encoding.Unicode.GetBytes(classText);
            }

            _deserializer.DeserializeInstances(bytes, ref offset, _onClassNeeded, null);
        }
    }
}

namespace Microsoft.PowerShell.DesiredStateConfiguration.Internal
{
    /// <summary>
    /// </summary>
    [SuppressMessage("Microsoft.MSInternal", "CA903:InternalNamespaceShouldNotContainPublicTypes",
        Justification = "Needed Internal use only")]
    internal class DscClassCacheEntry
    {
        /// <summary>
        /// Store the RunAs Credentials that this DSC resource will use.
        /// </summary>
        public DSCResourceRunAsCredential DscResRunAsCred;

        /// <summary>
        /// If we have implicitly imported this resource, we will set this field to true. This will
        /// only happen to InBox resources.
        /// </summary>
        public bool IsImportedImplicitly;

        /// <summary>
        /// A CimClass instance for this resource.
        /// </summary>
        public Microsoft.Management.Infrastructure.CimClass CimClassInstance;

        /// <summary>
        /// Initializes variables with default values.
        /// </summary>
        public DscClassCacheEntry() : this(DSCResourceRunAsCredential.Default, false, null) { }

        /// <summary>
        /// Initializes all values.
        /// </summary>
        /// <param name="aDSCResourceRunAsCredential"></param>
        /// <param name="aIsImportedImplicitly"></param>
        /// <param name="aCimClassInstance"></param>
        public DscClassCacheEntry(DSCResourceRunAsCredential aDSCResourceRunAsCredential, bool aIsImportedImplicitly, Microsoft.Management.Infrastructure.CimClass aCimClassInstance)
        {
            DscResRunAsCred = aDSCResourceRunAsCredential;
            IsImportedImplicitly = aIsImportedImplicitly;
            CimClassInstance = aCimClassInstance;
        }
    }

    /// <summary>
    /// </summary>
    [SuppressMessage("Microsoft.MSInternal", "CA903:InternalNamespaceShouldNotContainPublicTypes",
        Justification = "Needed Internal use only")]
    public static class DscClassCache
    {
        private const string InboxDscResourceModulePath = "WindowsPowershell\\v1.0\\Modules\\PsDesiredStateConfiguration";
        private const string reservedDynamicKeywords = "^(Synchronization|Certificate|IIS|SQL)$";

        private const string reservedProperties = "^(Require|Trigger|Notify|Before|After|Subscribe)$";

        private static PSTraceSource s_tracer = PSTraceSource.GetTracer("DSC", "DSC Class Cache");

        // Constants for items in the module qualified name (Module\Version\ClassName)
        private const int IndexModuleName = 0;
        private const int IndexModuleVersion = 1;
        private const int IndexClassName = 2;
        private const int IndexFriendlyName = 3;

        // Create a list of classes which are not actual DSC resources similar to what we do inside PSDesiredStateConfiguration.psm1
        private static readonly string[] s_hiddenResourceList =
        {
            "MSFT_BaseConfigurationProviderRegistration",
            "MSFT_CimConfigurationProviderRegistration",
            "MSFT_PSConfigurationProviderRegistration",
        };

        // Create a HashSet for fast lookup. According to MSDN, the time complexity of search for an element in a HashSet is O(1)
        private static readonly HashSet<string> s_hiddenResourceCache =
            new(s_hiddenResourceList, StringComparer.OrdinalIgnoreCase);

        // a collection to hold current importing script based resource file
        // this prevent circular importing case when the script resource existing in the same module with resources it import-dscresource
        private static readonly HashSet<string> s_currentImportingScriptFiles = new(StringComparer.OrdinalIgnoreCase);

        /// <summary>
        /// DSC class cache for this runspace.
        /// Cache stores the DSCRunAsBehavior, cim class and boolean to indicate if an Inbox resource has been implicitly imported.
        /// </summary>
        private static Dictionary<string, DscClassCacheEntry> ClassCache
        {
            get
            {
                if (t_classCache == null)
                {
                    t_classCache = new Dictionary<string, DscClassCacheEntry>(StringComparer.OrdinalIgnoreCase);
                }

                return t_classCache;
            }
        }

        [ThreadStatic]
        private static Dictionary<string, DscClassCacheEntry> t_classCache;

        /// <summary>
        /// DSC classname to source module mapper.
        /// </summary>
        private static Dictionary<string, Tuple<string, Version>> ByClassModuleCache
        {
            get
            {
                if (t_byClassModuleCache == null)
                {
                    t_byClassModuleCache = new Dictionary<string, Tuple<string, Version>>(StringComparer.OrdinalIgnoreCase);
                }

                return t_byClassModuleCache;
            }
        }

        [ThreadStatic]
        private static Dictionary<string, Tuple<string, Version>> t_byClassModuleCache;

        /// <summary>
        /// DSC filename to defined class mapper.
        /// </summary>
        private static Dictionary<string, List<Microsoft.Management.Infrastructure.CimClass>> ByFileClassCache
        {
            get
            {
                if (t_byFileClassCache == null)
                {
                    t_byFileClassCache = new Dictionary<string, List<Microsoft.Management.Infrastructure.CimClass>>(StringComparer.OrdinalIgnoreCase);
                }

                return t_byFileClassCache;
            }
        }

        [ThreadStatic]
        private static Dictionary<string, List<Microsoft.Management.Infrastructure.CimClass>> t_byFileClassCache;

        /// <summary>
        /// Filenames from which we have imported script dynamic keywords.
        /// </summary>
        private static HashSet<string> ScriptKeywordFileCache
        {
            get
            {
                if (t_scriptKeywordFileCache == null)
                {
                    t_scriptKeywordFileCache = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
                }

                return t_scriptKeywordFileCache;
            }
        }

        [ThreadStatic]
        private static HashSet<string> t_scriptKeywordFileCache;

        /// <summary>
        /// Default ModuleName and ModuleVersion to use.
        /// </summary>
        private static readonly Tuple<string, Version> s_defaultModuleInfoForResource =
            new("PSDesiredStateConfiguration", new Version("1.1"));

        /// <summary>
        /// Default ModuleName and ModuleVersion to use for meta configuration resources.
        /// </summary>
        internal static readonly Tuple<string, Version> DefaultModuleInfoForMetaConfigResource =
            new("PSDesiredStateConfigurationEngine", new Version("2.0"));

        /// <summary>
        /// A set of dynamic keywords that can be used in both configuration and meta configuration.
        /// </summary>
        internal static readonly HashSet<string> SystemResourceNames =
            new(StringComparer.OrdinalIgnoreCase) { "Node", "OMI_ConfigurationDocument" };

        /// <summary>
        /// When this property is set to true, DSC Cache will cache multiple versions of a resource.
        /// That means it will cache duplicate resource classes (class names for a resource in two different module versions are same).
        /// NOTE: This property should be set to false for DSC compiler related methods/functionality, such as Import-DscResource,
        ///       because the Mof serializer does not support deserialization of classes with different versions.
        /// </summary>
        [ThreadStatic]
        private static bool t_cacheResourcesFromMultipleModuleVersions;

        private static bool CacheResourcesFromMultipleModuleVersions
        {
            get
            {
                return t_cacheResourcesFromMultipleModuleVersions;
            }

            set
            {
                t_cacheResourcesFromMultipleModuleVersions = value;
            }
        }

        /// <summary>
        /// Initialize the class cache with the default classes in $ENV:SystemDirectory\Configuration.
        /// </summary>
        public static void Initialize()
        {
            Initialize(null, null);
        }

        /// <summary>
        /// Initialize the class cache with the default classes in $ENV:SystemDirectory\Configuration.
        /// </summary>
        /// <param name="errors">Collection of any errors encountered during initialization.</param>
        /// <param name="modulePathList">List of module path from where DSC PS modules will be loaded.</param>
        public static void Initialize(Collection<Exception> errors, List<string> modulePathList)
        {
            s_tracer.WriteLine("Initializing DSC class cache force={0}");

            if (Platform.IsLinux || Platform.IsMacOS)
            {
                //
                // Load the base schema files.
                //
                ClearCache();
                var dscConfigurationDirectory = Environment.GetEnvironmentVariable("DSC_HOME") ??
                                                "/etc/opt/omi/conf/dsc/configuration";

                if (!Directory.Exists(dscConfigurationDirectory))
                {
                    throw new DirectoryNotFoundException("Unable to find DSC schema store at " + dscConfigurationDirectory + ". Please ensure PS DSC for Linux is installed.");
                }

                var resourceBaseFile = Path.Combine(dscConfigurationDirectory, "BaseRegistration/BaseResource.schema.mof");
                ImportClasses(resourceBaseFile, s_defaultModuleInfoForResource, errors);

                var metaConfigFile = Path.Combine(dscConfigurationDirectory, "BaseRegistration/MSFT_DSCMetaConfiguration.mof");
                ImportClasses(metaConfigFile, s_defaultModuleInfoForResource, errors);

                var allResourceRoots = new string[] { dscConfigurationDirectory };

                //
                // Load all of the system resource schema files, searching
                //
                string resources;
                foreach (var resourceRoot in allResourceRoots)
                {
                    resources = Path.Combine(resourceRoot, "schema");
                    if (!Directory.Exists(resources))
                    {
                        continue;
                    }

                    foreach (var schemaFile in Directory.EnumerateDirectories(resources).SelectMany(d => Directory.EnumerateFiles(d, "*.schema.mof")))
                    {
                        ImportClasses(schemaFile, s_defaultModuleInfoForResource, errors);
                    }
                }

                // Linux DSC Modules are installed to the dscConfigurationDirectory, so no need to load them.
            }
            else
            {
                // DSC SxS scenario
                var configSystemPath = Utils.DefaultPowerShellAppBase;
                var systemResourceRoot = Path.Combine(configSystemPath, "Configuration");
                var inboxModulePath = "Modules\\PSDesiredStateConfiguration";

                if (!Directory.Exists(systemResourceRoot))
                {
                    configSystemPath = Platform.GetFolderPath(Environment.SpecialFolder.System);
                    systemResourceRoot = Path.Combine(configSystemPath, "Configuration");
                    inboxModulePath = InboxDscResourceModulePath;
                }

                var programFilesDirectory = Platform.GetFolderPath(Environment.SpecialFolder.ProgramFiles);
                Debug.Assert(programFilesDirectory != null, "Program Files environment variable does not exist!");
                var customResourceRoot = Path.Combine(programFilesDirectory, "WindowsPowerShell\\Configuration");
                Debug.Assert(Directory.Exists(customResourceRoot), "%ProgramFiles%\\WindowsPowerShell\\Configuration Directory does not exist");
                var allResourceRoots = new string[] { systemResourceRoot, customResourceRoot };
                //
                // Load the base schema files.
                //
                ClearCache();
                var resourceBaseFile = Path.Combine(systemResourceRoot, "BaseRegistration\\BaseResource.schema.mof");
                ImportClasses(resourceBaseFile, s_defaultModuleInfoForResource, errors);

                var metaConfigFile = Path.Combine(systemResourceRoot, "BaseRegistration\\MSFT_DSCMetaConfiguration.mof");
                ImportClasses(metaConfigFile, s_defaultModuleInfoForResource, errors);

                var metaConfigExtensionFile = Path.Combine(systemResourceRoot, "BaseRegistration\\MSFT_MetaConfigurationExtensionClasses.schema.mof");
                ImportClasses(metaConfigExtensionFile, DefaultModuleInfoForMetaConfigResource, errors);

                //
                // Load all of the system resource schema files, searching
                //
                string resources;
                foreach (var resourceRoot in allResourceRoots)
                {
                    resources = Path.Combine(resourceRoot, "Schema");
                    if (!Directory.Exists(resources))
                    {
                        continue;
                    }

                    foreach (var schemaFile in Directory.EnumerateDirectories(resources).SelectMany(d => Directory.EnumerateFiles(d, "*.schema.mof")))
                    {
                        ImportClasses(schemaFile, s_defaultModuleInfoForResource, errors);
                    }
                }

                // Load Regular and DSC PS modules
                bool importInBoxResourcesImplicitly = false;
                List<string> modulePaths = new();
                if (modulePathList == null || modulePathList.Count == 0)
                {
                    modulePaths.Add(Path.Combine(configSystemPath, inboxModulePath));
                    importInBoxResourcesImplicitly = true;
                }
                else
                {
                    foreach (string moduleFolderPath in modulePathList)
                    {
                        if (!Directory.Exists(moduleFolderPath))
                        {
                            continue;
                        }

                        foreach (string moduleDir in Directory.EnumerateDirectories(moduleFolderPath))
                        {
                            modulePaths.Add(moduleDir);
                        }
                    }
                }

                LoadDSCResourceIntoCache(errors, modulePaths, importInBoxResourcesImplicitly);
            }
        }

        /// <summary>
        /// Load DSC resources into Cache from moduleFolderPath.
        /// </summary>
        /// <param name="errors">Collection of any errors encountered during initialization.</param>
        /// <param name="modulePathList">Module path from where DSC PS modules will be loaded.</param>
        /// <param name="importInBoxResourcesImplicitly">
        /// if module is inbox.
        /// </param>
        private static void LoadDSCResourceIntoCache(Collection<Exception> errors, List<string> modulePathList, bool importInBoxResourcesImplicitly)
        {
            foreach (string moduleDir in modulePathList)
            {
                if (!Directory.Exists(moduleDir)) continue;

                var dscResourcesPath = Path.Combine(moduleDir, "DscResources");
                if (Directory.Exists(dscResourcesPath))
                {
                    foreach (string resourceDir in Directory.EnumerateDirectories(dscResourcesPath))
                    {
                        IEnumerable<string> schemaFiles = Directory.EnumerateFiles(resourceDir, "*.schema.mof");
                        if (!schemaFiles.Any())
                        {
                            continue;
                        }

                        Tuple<string, Version> moduleInfo = GetModuleInfoHelper(moduleDir, importInBoxResourcesImplicitly, isPsProviderModule: false);
                        if (moduleInfo == null)
                        {
                            continue;
                        }

                        foreach (string schemaFile in schemaFiles)
                        {
                            ImportClasses(schemaFile, moduleInfo, errors, importInBoxResourcesImplicitly);
                        }
                    }
                }
            }
        }

        /// <summary>
        /// Get the module name and module version.
        /// </summary>
        /// <param name="moduleFolderPath">
        /// Path to the module folder
        /// </param>
        /// <param name="importInBoxResourcesImplicitly">
        /// if module is inbox and we are importing resources implicitly
        /// </param>
        /// <param name="isPsProviderModule">
        /// Indicate a internal DSC module
        /// </param>
        /// <returns></returns>
        private static Tuple<string, Version> GetModuleInfoHelper(string moduleFolderPath, bool importInBoxResourcesImplicitly, bool isPsProviderModule)
        {
            string moduleName = "PsDesiredStateConfiguration";
            if (!importInBoxResourcesImplicitly)
            {
                moduleName = Path.GetFileName(moduleFolderPath);
            }

            string manifestPath = Path.Combine(moduleFolderPath, moduleName + ".psd1");
            s_tracer.WriteLine("DSC GetModuleVersion: Try retrieving module version information from file: {0}.", manifestPath);

            if (!File.Exists(manifestPath))
            {
                if (isPsProviderModule)
                {
                    // Some internal PSProviders do not come with a .psd1 file, such
                    // as MSFT_LogResource. We don't report error in this case.
                    return new Tuple<string, Version>(moduleName, new Version("1.0"));
                }
                else
                {
                    s_tracer.WriteLine("DSC GetModuleVersion: Manifest file '{0}' not exist.", manifestPath);
                    return null;
                }
            }

            try
            {
                Hashtable dataFileSetting =
                    PsUtils.GetModuleManifestProperties(
                        manifestPath,
                        PsUtils.ManifestModuleVersionPropertyName);

                object versionValue = dataFileSetting["ModuleVersion"];
                if (versionValue != null)
                {
                    Version moduleVersion;
                    if (LanguagePrimitives.TryConvertTo(versionValue, out moduleVersion))
                    {
                        return new Tuple<string, Version>(moduleName, moduleVersion);
                    }
                    else
                    {
                        s_tracer.WriteLine(
                            "DSC GetModuleVersion: ModuleVersion value '{0}' cannot be converted to System.Version. Skip the module '{1}'.",
                            versionValue, moduleName);
                    }
                }
                else
                {
                    s_tracer.WriteLine(
                        "DSC GetModuleVersion: Manifest file '{0}' does not contain ModuleVersion. Skip the module '{1}'.",
                        manifestPath, moduleName);
                }
            }
            catch (PSInvalidOperationException ex)
            {
                s_tracer.WriteLine(
                    "DSC GetModuleVersion: Error evaluating module manifest file '{0}', with error '{1}'. Skip the module '{2}'.",
                    manifestPath, ex, moduleName);
            }

            return null;
        }

        // Callback implementation...
        private static CimClass MyClassCallback(string serverName, string namespaceName, string className)
        {
            foreach (KeyValuePair<string, DscClassCacheEntry> cimClass in ClassCache)
            {
                string cachedClassName = cimClass.Key.Split(Utils.Separators.Backslash)[IndexClassName];
                if (string.Equals(cachedClassName, className, StringComparison.OrdinalIgnoreCase))
                {
                    return cimClass.Value.CimClassInstance;
                }
            }

            return null;
        }

        /// <summary>
        /// Import CIM classes from the given file.
        /// </summary>
        /// <param name="path"></param>
        /// <param name="moduleInfo"></param>
        /// <param name="errors"></param>
        /// <param name="importInBoxResourcesImplicitly"></param>
        /// <returns></returns>
        public static List<CimClass> ImportClasses(string path, Tuple<string, Version> moduleInfo, Collection<Exception> errors, bool importInBoxResourcesImplicitly = false)
        {
            if (string.IsNullOrEmpty(path))
            {
                throw PSTraceSource.NewArgumentNullException(nameof(path));
            }

            s_tracer.WriteLine("DSC ClassCache: importing file: {0}", path);

            var parser = new Microsoft.PowerShell.DesiredStateConfiguration.CimDSCParser(MyClassCallback);

            List<CimClass> classes = null;
            try
            {
                classes = parser.ParseSchemaMof(path);
            }
            catch (PSInvalidOperationException e)
            {
                // Ignore modules with invalid schemas.
                s_tracer.WriteLine("DSC ClassCache: Error importing file '{0}', with error '{1}'.  Skipping file.", path, e);
                if (errors != null)
                {
                    errors.Add(e);
                }
            }

            if (classes != null)
            {
                foreach (var c in classes)
                {
                    // Only add the class once...
                    var className = c.CimSystemProperties.ClassName;
                    string alias = GetFriendlyName(c);
                    var friendlyName = string.IsNullOrEmpty(alias) ? className : alias;
                    string moduleQualifiedResourceName = GetModuleQualifiedResourceName(moduleInfo.Item1, moduleInfo.Item2.ToString(), className, friendlyName);
                    DscClassCacheEntry cimClassInfo;

                    if (ClassCache.TryGetValue(moduleQualifiedResourceName, out cimClassInfo))
                    {
                        CimClass cimClass = cimClassInfo.CimClassInstance;

                        // If this is a nested object and we already have exactly same nested object, we will
                        // allow sharing of nested objects.
                        if (!IsSameNestedObject(cimClass, c))
                        {