_IOCompletionCallback.cs

using System.Security;

namespace System.Threading
{
    internal class _IOCompletionCallback
    {
        [SecurityCritical]
        private IOCompletionCallback _ioCompletionCallback;

        private ExecutionContext _executionContext;

        private uint _errorCode;

        private uint _numBytes;

        [SecurityCritical]
        private unsafe NativeOverlapped* _pOVERLAP;

        internal static ContextCallback _ccb;

        [SecuritySafeCritical]
        static _IOCompletionCallback()
        {
            _ccb = IOCompletionCallback_Context;
        }

        [SecurityCritical]
        internal unsafe _IOCompletionCallback(IOCompletionCallback ioCompletionCallback, ref StackCrawlMark stackMark)
        {
            _ioCompletionCallback = ioCompletionCallback;
            _executionContext = ExecutionContext.Capture(ref stackMark, ExecutionContext.CaptureOptions.IgnoreSyncCtx | ExecutionContext.CaptureOptions.OptimizeDefaultCase);
        }

        [SecurityCritical]
        internal unsafe static void IOCompletionCallback_Context(object state)
        {
            _IOCompletionCallback iOCompletionCallback = (_IOCompletionCallback)state;
            iOCompletionCallback._ioCompletionCallback(iOCompletionCallback._errorCode, iOCompletionCallback._numBytes, iOCompletionCallback._pOVERLAP);
        }

        [SecurityCritical]
        internal unsafe static void PerformIOCompletionCallback(uint errorCode, uint numBytes, NativeOverlapped* pOVERLAP)
        {
            do
            {
                Overlapped overlapped = OverlappedData.GetOverlappedFromNative(pOVERLAP).m_overlapped;
                _IOCompletionCallback iocbHelper = overlapped.iocbHelper;
                if (iocbHelper == null || iocbHelper._executionContext == null || iocbHelper._executionContext.IsDefaultFTContext(ignoreSyncCtx: true))
                {
                    IOCompletionCallback userCallback = overlapped.UserCallback;
                    userCallback(errorCode, numBytes, pOVERLAP);
                }
                else
                {
                    iocbHelper._errorCode = errorCode;
                    iocbHelper._numBytes = numBytes;
                    iocbHelper._pOVERLAP = pOVERLAP;
                    using (ExecutionContext executionContext = iocbHelper._executionContext.CreateCopy())
                    {
                        ExecutionContext.Run(executionContext, _ccb, iocbHelper, preserveSyncCtx: true);
                    }
                }
                OverlappedData.CheckVMForIOPacket(out pOVERLAP, out errorCode, out numBytes);
            }
            while (pOVERLAP != null);
        }
    }
}