Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / IO / Packaging / ManagedIStream.cs / 1305600 / ManagedIStream.cs
//---------------------------------------------------------------------------- // //// Copyright (C) Microsoft Corporation. All rights reserved. // // // Description: // Implements an IStream component initialized from an // object of type System.IO.Stream. // // History: // 03/28/2004: JohnLarc: Initial implementation //--------------------------------------------------------------------------- using System; using System.IO; using System.Diagnostics; // for Assert using System.IO.Packaging; // for native APIs using System.Runtime.InteropServices; // for Marshal, COMException, etc. using System.Runtime.InteropServices.ComTypes; // for IStream using System.Windows; // for ExceptionStringTable using System.Security; // for SecurityCritical using MS.Win32; // for NativeMethods namespace MS.Internal.IO.Packaging { // The class ManagedIStream is not COM-visible. Its purpose is to be able to invoke COM interfaces // from managed code rather than the contrary. internal class ManagedIStream : IStream { ////// Constructor /// internal ManagedIStream(Stream ioStream) { if (ioStream == null) { throw new ArgumentNullException("ioStream"); } _ioStream = ioStream; } ////// Read at most bufferSize bytes into buffer and return the effective /// number of bytes read in bytesReadPtr (unless null). /// ////// mscorlib disassembly shows the following MarshalAs parameters /// void Read([Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex=1)] byte[] pv, int cb, IntPtr pcbRead); /// This means marshaling code will have found the size of the array buffer in the parameter bufferSize. /// ////// Critical: calls Marshal.WriteInt32 which LinkDemands, takes pointers as input /// [SecurityCritical] void IStream.Read(Byte[] buffer, Int32 bufferSize, IntPtr bytesReadPtr) { Int32 bytesRead = _ioStream.Read(buffer, 0, (int) bufferSize); if (bytesReadPtr != IntPtr.Zero) { Marshal.WriteInt32(bytesReadPtr, bytesRead); } } ////// Move the stream pointer to the specified position. /// ////// System.IO.stream supports searching past the end of the stream, like /// OLE streams. /// newPositionPtr is not an out parameter because the method is required /// to accept NULL pointers. /// ////// Critical: calls Marshal.WriteInt64 which LinkDemands, takes pointers as input /// [SecurityCritical] void IStream.Seek(Int64 offset, Int32 origin, IntPtr newPositionPtr) { SeekOrigin seekOrigin; // The operation will generally be I/O bound, so there is no point in // eliminating the following switch by playing on the fact that // System.IO uses the same integer values as IStream for SeekOrigin. switch(origin) { case NativeMethods.STREAM_SEEK_SET: seekOrigin = SeekOrigin.Begin; break; case NativeMethods.STREAM_SEEK_CUR: seekOrigin = SeekOrigin.Current; break; case NativeMethods.STREAM_SEEK_END: seekOrigin = SeekOrigin.End; break; default: throw new ArgumentOutOfRangeException("origin"); } long position = _ioStream.Seek(offset, seekOrigin); // Dereference newPositionPtr and assign to the pointed location. if (newPositionPtr != IntPtr.Zero) { Marshal.WriteInt64(newPositionPtr, position); } } ////// Sets stream's size. /// void IStream.SetSize(Int64 libNewSize) { _ioStream.SetLength(libNewSize); } ////// Obtain stream stats. /// ////// STATSG has to be qualified because it is defined both in System.Runtime.InteropServices and /// System.Runtime.InteropServices.ComTypes. /// The STATSTG structure is shared by streams, storages and byte arrays. Members irrelevant to streams /// or not available from System.IO.Stream are not returned, which leaves only cbSize and grfMode as /// meaningful and available pieces of information. /// grfStatFlag is used to indicate whether the stream name should be returned and is ignored because /// this information is unavailable. /// void IStream.Stat(out System.Runtime.InteropServices.ComTypes.STATSTG streamStats, int grfStatFlag) { streamStats = new System.Runtime.InteropServices.ComTypes.STATSTG(); streamStats.type = NativeMethods.STGTY_STREAM; streamStats.cbSize = _ioStream.Length; // Return access information in grfMode. streamStats.grfMode = 0; // default value for each flag will be false if (_ioStream.CanRead && _ioStream.CanWrite) { streamStats.grfMode |= NativeMethods.STGM_READWRITE; } else if (_ioStream.CanRead) { streamStats.grfMode |= NativeMethods.STGM_READ; } else if (_ioStream.CanWrite) { streamStats.grfMode |= NativeMethods.STGM_WRITE; } else { // A stream that is neither readable nor writable is a closed stream. // Note the use of an exception that is known to the interop marshaller // (unlike ObjectDisposedException). throw new IOException(SR.Get(SRID.StreamObjectDisposed)); } } ////// Write at most bufferSize bytes from buffer. /// ////// Critical: calls Marshal.WriteInt32 which LinkDemands, takes pointers as input /// [SecurityCritical] void IStream.Write(Byte[] buffer, Int32 bufferSize, IntPtr bytesWrittenPtr) { _ioStream.Write(buffer, 0, bufferSize); if (bytesWrittenPtr != IntPtr.Zero) { // If fewer than bufferSize bytes had been written, an exception would // have been thrown, so it can be assumed we wrote bufferSize bytes. Marshal.WriteInt32(bytesWrittenPtr, bufferSize); } } #region Unimplemented methods ////// Create a clone. /// ////// Not implemented. /// void IStream.Clone(out IStream streamCopy) { streamCopy = null; throw new NotSupportedException(); } ////// Read at most bufferSize bytes from the receiver and write them to targetStream. /// ////// Not implemented. /// void IStream.CopyTo(IStream targetStream, Int64 bufferSize, IntPtr buffer, IntPtr bytesWrittenPtr) { throw new NotSupportedException(); } ////// Commit changes. /// ////// Only relevant to transacted streams. /// void IStream.Commit(Int32 flags) { throw new NotSupportedException(); } ////// Lock at most byteCount bytes starting at offset. /// ////// Not supported by System.IO.Stream. /// void IStream.LockRegion(Int64 offset, Int64 byteCount, Int32 lockType) { throw new NotSupportedException(); } ////// Undo writes performed since last Commit. /// ////// Relevant only to transacted streams. /// void IStream.Revert() { throw new NotSupportedException(); } ////// Unlock the specified region. /// ////// Not supported by System.IO.Stream. /// void IStream.UnlockRegion(Int64 offset, Int64 byteCount, Int32 lockType) { throw new NotSupportedException(); } #endregion Unimplemented methods #region Fields private Stream _ioStream; #endregion Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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