EvidenceBase.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Security / Policy / EvidenceBase.cs / 1305376 / EvidenceBase.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// [....]
// 
 
using System;
using System.Collections; 
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.IO;
using System.Runtime.InteropServices; 
#if FEATURE_SERIALIZATION
using System.Runtime.Serialization.Formatters.Binary; 
#endif // FEATURE_SERIALIZATION 
using System.Security.Permissions;
 
namespace System.Security.Policy
{
    /// 
    ///     Base class from which all objects to be used as Evidence must derive 
    /// 
    [ComVisible(true)] 
    [Serializable] 
    public abstract class EvidenceBase
    { 
        protected EvidenceBase()
        {
#if FEATURE_SERIALIZATION
            // All objects to be used as evidence must be serializable.  Make sure that any derived types 
            // are marked serializable to enforce this, since the attribute does not inherit down to derived
            // classes. 
            if (!GetType().IsSerializable) 
            {
                throw new InvalidOperationException(Environment.GetResourceString("Policy_EvidenceMustBeSerializable")); 
            }
#endif // FEATURE_SERIALIZATION
        }
 
        /// 
        ///     Since legacy evidence objects would be cloned by being serialized, the default implementation 
        ///     of EvidenceBase will do the same. 
        /// 
        [SecurityPermission(SecurityAction.Assert, SerializationFormatter = true)] 
        [SecuritySafeCritical]
        public virtual EvidenceBase Clone()
        {
#if FEATURE_SERIALIZATION 
            using (MemoryStream memoryStream = new MemoryStream())
            { 
                BinaryFormatter formatter = new BinaryFormatter(); 
                formatter.Serialize(memoryStream, this);
 
                memoryStream.Position = 0;
                return formatter.Deserialize(memoryStream) as EvidenceBase;
            }
#else // !FEATURE_SERIALIZATION 
            throw new NotImplementedException();
#endif // FEATURE_SERIALIZATION 
        } 
    }
 
    /// 
    ///     Interface for types which wrap Whidbey evidence objects for compatibility with v4 evidence rules
    /// 
    internal interface ILegacyEvidenceAdapter 
    {
        object EvidenceObject { get; } 
        Type EvidenceType { get; } 
    }
 
    /// 
    ///     Wrapper class to hold legacy evidence objects which do not derive from EvidenceBase, and allow
    ///     them to be held in the Evidence collection which expects to maintain lists of EvidenceBase only
    ///  
    [Serializable]
    internal sealed class LegacyEvidenceWrapper : EvidenceBase, ILegacyEvidenceAdapter 
    { 
        private object m_legacyEvidence;
 
        internal LegacyEvidenceWrapper(object legacyEvidence)
        {
            Contract.Assert(legacyEvidence != null);
            Contract.Assert(legacyEvidence.GetType() != typeof(EvidenceBase), "Attempt to wrap an EvidenceBase in a LegacyEvidenceWrapper"); 
            Contract.Assert(legacyEvidence.GetType().IsSerializable, "legacyEvidence.GetType().IsSerializable");
 
            m_legacyEvidence = legacyEvidence; 
        }
 
        public object EvidenceObject
        {
            get { return m_legacyEvidence; }
        } 

        public Type EvidenceType 
        { 
            get { return m_legacyEvidence.GetType(); }
        } 

        public override bool Equals(object obj)
        {
            return m_legacyEvidence.Equals(obj); 
        }
 
        public override int GetHashCode() 
        {
            return m_legacyEvidence.GetHashCode(); 
        }
    }

    ///  
    ///     Pre-v4 versions of the runtime allow multiple pieces of evidence that all have the same type.
    ///     This type wraps those evidence objects into a single type of list, allowing legacy code to continue 
    ///     to work with the Evidence collection that does not expect multiple evidences of the same type. 
    ///
    ///     This may not be limited to LegacyEvidenceWrappers, since it's valid for legacy code to add multiple 
    ///     objects of built-in evidence to an Evidence collection.  The built-in evidence now derives from
    ///     EvienceObject, so when the legacy code runs on v4, it may end up attempting to add multiple
    ///     Hash evidences for intsance.
    ///  
    [Serializable]
    internal sealed class LegacyEvidenceList : EvidenceBase, IEnumerable, ILegacyEvidenceAdapter 
    { 
        private List m_legacyEvidenceList = new List();
 
        public object EvidenceObject
        {
            get
            { 
                // We'll choose the first item in the list to represent us if we're forced to return only
                // one object. This can occur if multiple pieces of evidence are added via the legacy APIs, 
                // and then the new APIs are used to retrieve that evidence. 
                return m_legacyEvidenceList.Count > 0 ? m_legacyEvidenceList[0] : null;
            } 
        }

        public Type EvidenceType
        { 
            get
            { 
                Contract.Assert(m_legacyEvidenceList.Count > 0, "No items in LegacyEvidenceList, cannot tell what type they are"); 

                ILegacyEvidenceAdapter adapter = m_legacyEvidenceList[0] as ILegacyEvidenceAdapter; 
                return adapter == null ? m_legacyEvidenceList[0].GetType() : adapter.EvidenceType;
            }
        }
 
        public void Add(EvidenceBase evidence)
        { 
            Contract.Assert(evidence != null); 
            Contract.Assert(m_legacyEvidenceList.Count == 0 || EvidenceType == evidence.GetType() || (evidence is LegacyEvidenceWrapper && (evidence as LegacyEvidenceWrapper).EvidenceType == EvidenceType),
                            "LegacyEvidenceList must be ----geonous"); 
            Contract.Assert(evidence.GetType() != typeof(LegacyEvidenceList),
                            "Attempt to add a legacy evidence list to another legacy evidence list");

            m_legacyEvidenceList.Add(evidence); 
        }
 
        public IEnumerator GetEnumerator() 
        {
            return m_legacyEvidenceList.GetEnumerator(); 
        }

        IEnumerator System.Collections.IEnumerable.GetEnumerator()
        { 
            return m_legacyEvidenceList.GetEnumerator();
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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EvidenceBase.cs source code in C# .NET

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