SafeHandles.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Data / System / Data / OleDb / SafeHandles.cs / 1305376 / SafeHandles.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
namespace System.Data.OleDb {
 
    using System;
    using System.Data.Common;
    using System.Data.ProviderBase;
    using System.Diagnostics; 
    using System.Globalization;
    using System.Runtime.CompilerServices; 
    using System.Runtime.InteropServices; 
    using System.Security;
    using System.Security.Permissions; 
    using System.Threading;
    using System.Runtime.ConstrainedExecution;

    internal sealed class DualCoTaskMem : SafeHandle { 

        private IntPtr handle2;   // this must be protected so derived classes can use out params. 
 
        private DualCoTaskMem() : base(IntPtr.Zero, true) {
            this.handle2 = IntPtr.Zero; 
        }

        // IDBInfo.GetLiteralInfo
        internal DualCoTaskMem(UnsafeNativeMethods.IDBInfo dbInfo, int[] literals, out int literalCount, out IntPtr literalInfo, out OleDbHResult hr) : this() { 
            int count = (null != literals) ? literals.Length : 0;
 
            Bid.Trace("\n"); 
            hr = dbInfo.GetLiteralInfo(count, literals, out literalCount, out base.handle, out this.handle2);
            literalInfo = base.handle; 
            Bid.Trace(" %08X{HRESULT}\n", hr);
        }

        // IColumnsInfo.GetColumnInfo 
        internal DualCoTaskMem(UnsafeNativeMethods.IColumnsInfo columnsInfo, out IntPtr columnCount, out IntPtr columnInfos, out OleDbHResult hr) : this() {
            Bid.Trace("\n"); 
            hr = columnsInfo.GetColumnInfo(out columnCount, out base.handle, out this.handle2); 
            columnInfos = base.handle;
            Bid.Trace(" %08X{HRESULT}\n", hr); 
        }

        // IDBSchemaRowset.GetSchemas
        internal DualCoTaskMem(UnsafeNativeMethods.IDBSchemaRowset dbSchemaRowset, out int schemaCount, out IntPtr schemaGuids, out IntPtr schemaRestrictions, out OleDbHResult hr) : this() { 
            Bid.Trace("\n");
            hr = dbSchemaRowset.GetSchemas(out schemaCount, out base.handle, out this.handle2); 
            schemaGuids = base.handle; 
            schemaRestrictions = this.handle2;
            Bid.Trace(" %08X{HRESULT}\n", hr); 
        }

        internal DualCoTaskMem(UnsafeNativeMethods.IColumnsRowset icolumnsRowset, out IntPtr cOptColumns, out OleDbHResult hr) : base(IntPtr.Zero, true) {
            Bid.Trace("\n"); 
            hr = icolumnsRowset.GetAvailableColumns(out cOptColumns, out base.handle);
            Bid.Trace(" %08X{HRESULT}\n", hr); 
        } 

 
        public override bool IsInvalid {
            get {
                return (((IntPtr.Zero == base.handle)) && (IntPtr.Zero == this.handle2));
            } 
        }
 
        protected override bool ReleaseHandle() { 
            // NOTE: The SafeHandle class guarantees this will be called exactly once.
 
            IntPtr ptr = base.handle;
            base.handle = IntPtr.Zero;
            if (IntPtr.Zero != ptr) {
                SafeNativeMethods.CoTaskMemFree(ptr); 
            }
 
            ptr = this.handle2; 
            this.handle2 = IntPtr.Zero;
            if (IntPtr.Zero != ptr) { 
                SafeNativeMethods.CoTaskMemFree(ptr);
            }
            return true;
        } 
    }
 
    internal sealed class RowHandleBuffer : DbBuffer { 

        internal RowHandleBuffer(IntPtr rowHandleFetchCount) : base((int)rowHandleFetchCount*ADP.PtrSize) { 
        }

        internal IntPtr GetRowHandle(int index) {
            IntPtr value = ReadIntPtr( index * ADP.PtrSize); 
            Debug.Assert(ODB.DB_NULL_HROW != value, "bad rowHandle");
            return value; 
        } 
    }
 
    internal sealed class StringMemHandle : DbBuffer {

        internal StringMemHandle(string value) : base((null != value) ? checked(2+2*value.Length) : 0) {
            if (null != value) { 
                // null-termination exists because of the extra 2+ which is zero'd during on allocation
                WriteCharArray(0, value.ToCharArray(), 0, value.Length); 
            } 
        }
    } 

    internal sealed class ChapterHandle : WrappedIUnknown {

        internal static readonly ChapterHandle DB_NULL_HCHAPTER = new ChapterHandle(IntPtr.Zero); 
        private IntPtr _chapterHandle;
 
        internal static ChapterHandle CreateChapterHandle(object chapteredRowset, RowBinding binding, int valueOffset) { 
            if ((null == chapteredRowset) || (IntPtr.Zero == binding.ReadIntPtr(valueOffset))) {
                return ChapterHandle.DB_NULL_HCHAPTER; 
            }
            return new ChapterHandle(chapteredRowset, binding, valueOffset);
        }
 
         // from ADODBRecordSetConstruction we do not want to release the initial chapter handle
        internal static ChapterHandle CreateChapterHandle(IntPtr chapter) { 
            if (IntPtr.Zero == chapter) { 
                return ChapterHandle.DB_NULL_HCHAPTER;
            } 
            return new ChapterHandle(chapter);
        }

        // from ADODBRecordSetConstruction we do not want to release the initial chapter handle 
        private ChapterHandle(IntPtr chapter) : base((object)null) {
            _chapterHandle = chapter; 
        } 

        private ChapterHandle(object chapteredRowset, RowBinding binding, int valueOffset) : base(chapteredRowset) { 
            RuntimeHelpers.PrepareConstrainedRegions();
            try {} finally {
                _chapterHandle = binding.InterlockedExchangePointer(valueOffset);
            } 
        }
 
        internal IntPtr HChapter { 
            get {
                return _chapterHandle; 
            }
        }

        protected override bool ReleaseHandle() { 
            // NOTE: The SafeHandle class guarantees this will be called exactly once and is non-interrutible.
            IntPtr chapter = _chapterHandle; 
            _chapterHandle = IntPtr.Zero; 

            if ((IntPtr.Zero != base.handle) && (IntPtr.Zero != chapter)) { 
                Bid.Trace(" Chapter=%Id\n", chapter);
                OleDbHResult hr = (OleDbHResult)NativeOledbWrapper.IChapteredRowsetReleaseChapter(base.handle, chapter);
                Bid.Trace(" %08X{HRESULT}\n", hr);
            } 
            return base.ReleaseHandle();
        } 
    } 
}

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

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