CompressedStack.cs source code in C# .NET

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Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Threading / CompressedStack.cs / 3 / CompressedStack.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*==============================================================================
** 
** Class: CompressedStack 
**
** Purpose: Managed wrapper for the security stack compression implementation 
**
=============================================================================*/

namespace System.Threading 
{
    using System.Security; 
    using System.Security.Permissions; 
    using System.Runtime.InteropServices;
    using System.Runtime.CompilerServices; 
    using System.Runtime.ConstrainedExecution;
    using System.Reflection;
    using System.Collections;
    using System.Threading; 
    using System.Runtime.Serialization;
 
 
    internal struct CompressedStackSwitcher: IDisposable
    { 
        internal CompressedStack curr_CS;
        internal CompressedStack prev_CS;
        internal IntPtr prev_ADStack;
 

        public override bool Equals(Object obj) 
        { 
            if (obj == null || !(obj is CompressedStackSwitcher))
                return false; 
            CompressedStackSwitcher sw = (CompressedStackSwitcher)obj;
            return (this.curr_CS == sw.curr_CS && this.prev_CS == sw.prev_CS && this.prev_ADStack == sw.prev_ADStack);
        }
 
        public override int GetHashCode()
        { 
        	return ToString().GetHashCode(); 
        }
 
        public static bool operator ==(CompressedStackSwitcher c1, CompressedStackSwitcher c2)
        {
            return c1.Equals(c2);
        } 

        public static bool operator !=(CompressedStackSwitcher c1, CompressedStackSwitcher c2) 
        { 
            return !c1.Equals(c2);
        } 
        /// 
        void IDisposable.Dispose()
        {
            Undo(); 
        }
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        internal bool UndoNoThrow()
        { 
            try
            {
                Undo();
            } 
            catch
            { 
                return false; 
            }
            return true; 
        }


        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        public void Undo()
        { 
            if (curr_CS == null && prev_CS == null) 
                return;
            if (prev_ADStack != (IntPtr)0) 
                CompressedStack.RestoreAppDomainStack(prev_ADStack);
            CompressedStack.SetCompressedStackThread(prev_CS);

            prev_CS = null; 
            curr_CS = null;
            prev_ADStack = (IntPtr)0; 
        } 
    }
 
     internal class SafeCompressedStackHandle : SafeHandle
     {
        public SafeCompressedStackHandle() : base(IntPtr.Zero, true)
        { 
        }
 
        public override bool IsInvalid { 
            get { return handle == IntPtr.Zero; }
        } 

        override protected bool ReleaseHandle()
        {
            CompressedStack.DestroyDelayedCompressedStack(handle); 
            handle = IntPtr.Zero;
            return true; 
        } 
     }
 


     [Serializable()]
    public sealed class CompressedStack:ISerializable 
    {
 
        private PermissionListSet m_pls; 
        private SafeCompressedStackHandle m_csHandle;
 

        internal PermissionListSet PLS
        {
            get 
            {
                return m_pls; 
            } 
        }
 
        internal CompressedStack( SafeCompressedStackHandle csHandle )
        {
            m_csHandle = csHandle;
        } 

        private CompressedStack(SafeCompressedStackHandle csHandle, PermissionListSet pls) 
        { 
            this.m_csHandle = csHandle;
            this.m_pls = pls; 
        }

        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.SerializationFormatter)] 		
        public void GetObjectData(SerializationInfo info, StreamingContext context) 
        {
            if (info==null) 
                throw new ArgumentNullException("info"); 
            CompleteConstruction(null);
            info.AddValue("PLS", this.m_pls); 
        }

        private CompressedStack(SerializationInfo info, StreamingContext context)
        { 
            this.m_pls = (PermissionListSet)info.GetValue("PLS", typeof(PermissionListSet));
        } 
 
        internal SafeCompressedStackHandle CompressedStackHandle
        { 
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            get
            {
                return m_csHandle; 
            }
        } 
 
        [StrongNameIdentityPermissionAttribute(SecurityAction.LinkDemand, PublicKey = "0x00000000000000000400000000000000"),
         SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)] 
        public static CompressedStack GetCompressedStack()
        {
            // This is a Capture()
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller; 
            return CompressedStack.GetCompressedStack(ref stackMark);
        } 
 
        internal static CompressedStack GetCompressedStack(ref StackCrawlMark stackMark)
        { 
            CompressedStack cs;
            CompressedStack innerCS = null;
            if (CodeAccessSecurityEngine.QuickCheckForAllDemands())
            { 
                cs = new CompressedStack(null);
            } 
            else if (CodeAccessSecurityEngine.AllDomainsHomogeneousWithNoStackModifiers()) 
            {
                // if all AppDomains on the stack are homogeneous, we don't need to walk the stack 
                // however, we do need to capture the AppDomain stack.
                cs = new CompressedStack(GetDelayedCompressedStack(ref stackMark, false));
                cs.m_pls = PermissionListSet.CreateCompressedState_HG();
            } 
            else
            { 
                // regular stackwalking case 
                cs = new CompressedStack(GetDelayedCompressedStack( ref stackMark, true ));
                if (cs.CompressedStackHandle != null && IsImmediateCompletionCandidate(cs.CompressedStackHandle, out innerCS)) 
                {
                    cs.CompleteConstruction(innerCS);
                    DestroyDCSList(cs.CompressedStackHandle);
                } 
            }
            return cs; 
        } 

        public static CompressedStack Capture() 
        {
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller;
            return GetCompressedStack(ref stackMark);
        } 

        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.Infrastructure), 
         DynamicSecurityMethodAttribute()] 
        public static void Run(CompressedStack compressedStack, ContextCallback callback, Object state)
        { 

            if (compressedStack == null )
            {
                throw new ArgumentException(Environment.GetResourceString("Arg_NamedParamNull"),"compressedStack"); 
            }
            if (cleanupCode == null) 
            { 
                tryCode = new RuntimeHelpers.TryCode(runTryCode);
                cleanupCode = new RuntimeHelpers.CleanupCode(runFinallyCode); 
            }

            CompressedStackRunData runData = new CompressedStackRunData(compressedStack, callback, state);
            RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(tryCode, cleanupCode, runData); 
        }
 
        internal class CompressedStackRunData 
        {
            internal CompressedStack cs; 
            internal ContextCallback callBack;
            internal Object state;
            internal CompressedStackSwitcher cssw;
            internal CompressedStackRunData(CompressedStack cs, ContextCallback cb, Object state) 
            {
                this.cs = cs; 
                this.callBack = cb; 
                this.state = state;
                this.cssw = new CompressedStackSwitcher(); 
            }
        }
        static internal void runTryCode(Object userData)
        { 
            CompressedStackRunData rData = (CompressedStackRunData) userData;
            rData.cssw = SetCompressedStack(rData.cs, GetCompressedStackThread()); 
            rData.callBack(rData.state); 

        } 

        [PrePrepareMethod]
        static internal void runFinallyCode(Object userData, bool exceptionThrown)
        { 
            CompressedStackRunData rData = (CompressedStackRunData) userData;
            rData.cssw.Undo(); 
        } 

        static internal RuntimeHelpers.TryCode tryCode; 
        static internal RuntimeHelpers.CleanupCode cleanupCode;


        internal static CompressedStackSwitcher SetCompressedStack(CompressedStack cs, CompressedStack prevCS) 
        {
            CompressedStackSwitcher cssw = new CompressedStackSwitcher(); 
            RuntimeHelpers.PrepareConstrainedRegions(); 
            try
            { 
                // Order is important in this block.
                // Also, we dont want any THreadAborts happening when we try to set it
                RuntimeHelpers.PrepareConstrainedRegions();
                try 
                {
                    // Empty try block to ensure no ThreadAborts in the finally block 
                } 
                finally
                { 
                    // SetCompressedStackThread can throw - only if it suceeds we shd update the switcher and overrides
                    SetCompressedStackThread(cs);
                    cssw.prev_CS = prevCS;
                    cssw.curr_CS = cs; 
                    cssw.prev_ADStack = SetAppDomainStack(cs);
                } 
            } 
            catch
            { 
                cssw.UndoNoThrow();
                throw; // throw the original exception
            }
            return cssw; 
        }
 
 
        [ComVisible(false)]
        public CompressedStack CreateCopy() 
        {
            return new CompressedStack(this.m_csHandle, this.m_pls);
        }
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        internal static IntPtr SetAppDomainStack(CompressedStack cs) 
        { 
            //Update the AD Stack on the thread and return the previous AD Stack
            return Thread.CurrentThread.SetAppDomainStack((cs == null ? null:cs.CompressedStackHandle)); 
        }


        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        internal static void RestoreAppDomainStack(IntPtr appDomainStack)
        { 
            Thread.CurrentThread.RestoreAppDomainStack(appDomainStack); //Restore the previous AD Stack 
        }
        internal static CompressedStack GetCompressedStackThread() 
        {
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate();
            if (ec != null && ec.SecurityContext != null)
                return ec.SecurityContext.CompressedStack; 
            return null;
        } 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        internal static void SetCompressedStackThread(CompressedStack cs)
        { 
            ExecutionContext ec = Thread.CurrentThread.ExecutionContext;
            if (ec.SecurityContext != null)
                ec.SecurityContext.CompressedStack = cs;
            else if (cs != null) 
            {
                SecurityContext sc = new SecurityContext(); 
                sc.CompressedStack = cs; 
                ec.SecurityContext = sc;
            } 
        }


        internal bool CheckDemand(CodeAccessPermission demand, PermissionToken permToken, RuntimeMethodHandle rmh) 
        {
            CompleteConstruction(null); 
 
            if (PLS == null)
                return SecurityRuntime.StackHalt; 
            else
                return PLS.CheckDemand(demand, permToken, rmh);

        } 

        internal bool CheckSetDemand(PermissionSet pset , RuntimeMethodHandle rmh) 
        { 
            CompleteConstruction(null);
 
            if (PLS == null)
                return SecurityRuntime.StackHalt;
            else
                return PLS.CheckSetDemand(pset, rmh); 
        }
 
        ///  
        ///     Demand which succeeds if either a set of special permissions or a permission set is granted
        ///     to the call stack 
        /// 
        /// set of flags to check (See PermissionType)
        /// alternate permission set to check
        internal void DemandFlagsOrGrantSet(int flags, PermissionSet grantSet) 
        {
            CompleteConstruction(null); 
            if (PLS == null) 
                return;
 
            PLS.DemandFlagsOrGrantSet(flags, grantSet);
        }

        internal void GetZoneAndOrigin(ArrayList zoneList, ArrayList originList, PermissionToken zoneToken, PermissionToken originToken) 
        {
            CompleteConstruction(null); 
            if (PLS != null) 
                PLS.GetZoneAndOrigin(zoneList,originList,zoneToken,originToken);
            return; 
        }

        internal void CompleteConstruction(CompressedStack innerCS)
        { 
            if (PLS != null)
                return; 
            PermissionListSet pls = PermissionListSet.CreateCompressedState(this, innerCS); 
            lock (this)
            { 
                if (PLS == null)
                    m_pls = pls;
            }
        } 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        internal extern static SafeCompressedStackHandle GetDelayedCompressedStack(ref StackCrawlMark stackMark, 
                                                                                   bool walkStack); 

        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static void DestroyDelayedCompressedStack( IntPtr unmanagedCompressedStack );

        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        internal extern static void DestroyDCSList( SafeCompressedStackHandle compressedStack ); 

 
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static int GetDCSCount(SafeCompressedStackHandle compressedStack);
 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        internal extern static bool IsImmediateCompletionCandidate(SafeCompressedStackHandle compressedStack, out CompressedStack innerCS);

        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static DomainCompressedStack GetDomainCompressedStack(SafeCompressedStackHandle compressedStack, int index);
 
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static void GetHomogeneousPLS(PermissionListSet hgPLS);
 

    }

    //********************************************************* 
    // New Implementation of CompressedStack creation/demand eval - NewCompressedStack/DomainCompressedStack
    //********************************************************* 
    [Serializable()] 
    internal sealed class DomainCompressedStack
    { 
        // Managed equivalent of DomainCompressedStack - used to perform demand evaluation
        private PermissionListSet m_pls;
        // Did we terminate construction on this DCS and therefore, should we terminate construction on the rest of the CS?
        private bool m_bHaltConstruction; 

 
        // CompresedStack interacts with this class purely through the three properties marked internal 
        // Zone, Origin, AGRList.
        internal PermissionListSet PLS 
        {
            get
            {
                 return m_pls; 
            }
        } 
 
        internal bool ConstructionHalted
        { 
            get
            {
                 return m_bHaltConstruction;
            } 
        }
 
 

        // Called from the VM only. 
        private static DomainCompressedStack CreateManagedObject(IntPtr unmanagedDCS)
        {
            DomainCompressedStack newDCS = new DomainCompressedStack();
            newDCS.m_pls = PermissionListSet.CreateCompressedState(unmanagedDCS, out newDCS.m_bHaltConstruction); 
            // return the created object
            return newDCS; 
        } 

        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static int GetDescCount(IntPtr dcs);

        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        internal extern static void GetDomainPermissionSets(IntPtr dcs, out PermissionSet granted, out PermissionSet refused); 

        // returns true if the descriptor is a FrameSecurityDescriptor 
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal extern static bool GetDescriptorInfo(IntPtr dcs, int index, out PermissionSet granted, out PermissionSet refused, out Assembly assembly, out FrameSecurityDescriptor fsd);
 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        internal extern static bool IgnoreDomain(IntPtr dcs);
    }
 
}

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