UnmanagedMemoryStream Class

Definition

Namespace:

System.IO

Assembly:

System.Runtime.dll

Source:

UnmanagedMemoryStream.cs

Important

This API is not CLS-compliant.

Provides access to unmanaged blocks of memory from managed code.

public ref class UnmanagedMemoryStream : System::IO::Stream

public class UnmanagedMemoryStream : System.IO.Stream

type UnmanagedMemoryStream = class
    inherit Stream

Public Class UnmanagedMemoryStream
Inherits Stream

Inheritance

Object

MarshalByRefObject

Stream

UnmanagedMemoryStream

Derived

System.IO.MemoryMappedFiles.MemoryMappedViewStream

Examples

The following code example demonstrates how to read from and write to unmanaged memory using the UnmanagedMemoryStream class. A block of unmanaged memory is allocated and de-allocated using the Marshal class.

// Note: you must compile this sample using the unsafe flag.
// From the command line, type the following: csc sample.cs /unsafe

using System;
using System.IO;
using System.Text;
using System.Runtime.InteropServices;

unsafe class TestWriter
{
    static void Main()
    {
        // Create some data to read and write.
        byte[] message = UnicodeEncoding.Unicode.GetBytes("Here is some data.");

        // Allocate a block of unmanaged memory and return an IntPtr object.	
        IntPtr memIntPtr = Marshal.AllocHGlobal(message.Length);

        // Get a byte pointer from the IntPtr object.
        byte* memBytePtr = (byte*)memIntPtr.ToPointer();

        // Create an UnmanagedMemoryStream object using a pointer to unmanaged memory.
        UnmanagedMemoryStream writeStream = new UnmanagedMemoryStream(memBytePtr, message.Length, message.Length, FileAccess.Write);

        // Write the data.
        writeStream.Write(message, 0, message.Length);

        // Close the stream.
        writeStream.Close();

        // Create another UnmanagedMemoryStream object using a pointer to unmanaged memory.
        UnmanagedMemoryStream readStream = new UnmanagedMemoryStream(memBytePtr, message.Length, message.Length, FileAccess.Read);

        // Create a byte array to hold data from unmanaged memory.
        byte[] outMessage = new byte[message.Length];

        // Read from unmanaged memory to the byte array.
        readStream.Read(outMessage, 0, message.Length);

        // Close the stream.
        readStream.Close();

        // Display the data to the console.
        Console.WriteLine(UnicodeEncoding.Unicode.GetString(outMessage));

        // Free the block of unmanaged memory.
        Marshal.FreeHGlobal(memIntPtr);

        Console.ReadLine();
    }
}

Remarks

This class supports access to unmanaged memory using the existing stream-based model and does not require that the contents in the unmanaged memory be copied to the heap.

Note

This type implements the IDisposable interface, but does not actually have any resources to dispose. This means that disposing it by directly calling Dispose() or by using a language construct such as using (in C#) or Using (in Visual Basic) is not necessary.

Constructors

UnmanagedMemoryStream()	Initializes a new instance of the UnmanagedMemoryStream class.
UnmanagedMemoryStream(Byte*, Int64)	Initializes a new instance of the UnmanagedMemoryStream class using the specified location and memory length.
UnmanagedMemoryStream(Byte*, Int64, Int64, FileAccess)	Initializes a new instance of the UnmanagedMemoryStream class using the specified location, memory length, total amount of memory, and file access values.
UnmanagedMemoryStream(SafeBuffer, Int64, Int64)	Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset and length.
UnmanagedMemoryStream(SafeBuffer, Int64, Int64, FileAccess)	Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset, length, and file access.

Properties

CanRead	Gets a value indicating whether a stream supports reading.
CanSeek	Gets a value indicating whether a stream supports seeking.
CanTimeout	Gets a value that determines whether the current stream can time out. (Inherited from Stream)
CanWrite	Gets a value indicating whether a stream supports writing.
Capacity	Gets the stream length (size) or the total amount of memory assigned to a stream (capacity).
Length	Gets the length of the data in a stream.
Position	Gets or sets the current position in a stream.
PositionPointer	Gets or sets a byte pointer to a stream based on the current position in the stream.
ReadTimeout	Gets or sets a value, in milliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream)
WriteTimeout	Gets or sets a value, in milliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream)

Methods

BeginRead(Byte[], Int32, Int32, AsyncCallback, Object)	Begins an asynchronous read operation. (Consider using ReadAsync(Byte[], Int32, Int32) instead.) (Inherited from Stream)
BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object)	Begins an asynchronous write operation. (Consider using WriteAsync(Byte[], Int32, Int32) instead.) (Inherited from Stream)
Close()	Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. Instead of calling this method, ensure that the stream is properly disposed. (Inherited from Stream)
CopyTo(Stream)	Reads the bytes from the current stream and writes them to another stream. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyTo(Stream, Int32)	Reads the bytes from the current stream and writes them to another stream, using a specified buffer size. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream)	Asynchronously reads the bytes from the current stream and writes them to another stream. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream, CancellationToken)	Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified cancellation token. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream, Int32)	Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream, Int32, CancellationToken)	Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size and cancellation token. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CreateObjRef(Type)	Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject)
CreateWaitHandle()	Obsolete. Allocates a WaitHandle object. (Inherited from Stream)
Dispose()	Releases all resources used by the Stream. (Inherited from Stream)
Dispose(Boolean)	Releases the unmanaged resources used by the UnmanagedMemoryStream and optionally releases the managed resources.
DisposeAsync()	Asynchronously releases the unmanaged resources used by the Stream. (Inherited from Stream)
EndRead(IAsyncResult)	Waits for the pending asynchronous read to complete. (Consider using ReadAsync(Byte[], Int32, Int32) instead.) (Inherited from Stream)
EndWrite(IAsyncResult)	Ends an asynchronous write operation. (Consider using WriteAsync(Byte[], Int32, Int32) instead.) (Inherited from Stream)
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Flush()	Overrides the Flush() method so that no action is performed.
FlushAsync()	Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device. (Inherited from Stream)
FlushAsync(CancellationToken)	Overrides the FlushAsync(CancellationToken) method so that the operation is cancelled if specified, but no other action is performed.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetLifetimeService()	Obsolete. Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject)
GetType()	Gets the Type of the current instance. (Inherited from Object)
Initialize(Byte*, Int64, Int64, FileAccess)	Initializes a new instance of the UnmanagedMemoryStream class by using a pointer to an unmanaged memory location.
Initialize(SafeBuffer, Int64, Int64, FileAccess)	Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset, length, and file access.
InitializeLifetimeService()	Obsolete. Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
MemberwiseClone(Boolean)	Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject)
ObjectInvariant()	Obsolete. Provides support for a Contract. (Inherited from Stream)
Read(Byte[], Int32, Int32)	Reads the specified number of bytes into the specified array.
Read(Span<Byte>)	Reads all the bytes of this unmanaged memory stream into the specified span of bytes.
ReadAsync(Byte[], Int32, Int32)	Asynchronously reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. (Inherited from Stream)
ReadAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously reads the specified number of bytes into the specified array.
ReadAsync(Memory<Byte>, CancellationToken)	Asynchronously reads the unmanaged memory stream bytes into the memory region.
ReadAtLeast(Span<Byte>, Int32, Boolean)	Reads at least a minimum number of bytes from the current stream and advances the position within the stream by the number of bytes read. (Inherited from Stream)
ReadAtLeastAsync(Memory<Byte>, Int32, Boolean, CancellationToken)	Asynchronously reads at least a minimum number of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests. (Inherited from Stream)
ReadByte()	Reads a byte from a stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream.
ReadExactly(Byte[], Int32, Int32)	Reads count number of bytes from the current stream and advances the position within the stream. (Inherited from Stream)
ReadExactly(Span<Byte>)	Reads bytes from the current stream and advances the position within the stream until the buffer is filled. (Inherited from Stream)
ReadExactlyAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously reads count number of bytes from the current stream, advances the position within the stream, and monitors cancellation requests. (Inherited from Stream)
ReadExactlyAsync(Memory<Byte>, CancellationToken)	Asynchronously reads bytes from the current stream, advances the position within the stream until the buffer is filled, and monitors cancellation requests. (Inherited from Stream)
Seek(Int64, SeekOrigin)	Sets the current position of the current stream to the given value.
SetLength(Int64)	Sets the length of a stream to a specified value.
ToString()	Returns a string that represents the current object. (Inherited from Object)
Write(Byte[], Int32, Int32)	Writes a block of bytes to the current stream using data from a buffer.
Write(ReadOnlySpan<Byte>)	Writes a block of bytes to the current unmanaged memory stream using data from the provided span of bytes.
WriteAsync(Byte[], Int32, Int32)	Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written. (Inherited from Stream)
WriteAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously writes a sequence of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.
WriteAsync(ReadOnlyMemory<Byte>, CancellationToken)	Asynchronously writes a span of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.
WriteByte(Byte)	Writes a byte to the current position in the file stream.

Extension Methods

CopyToAsync(Stream, PipeWriter, CancellationToken)	Asynchronously reads the bytes from the Stream and writes them to the specified PipeWriter, using a cancellation token.
ConfigureAwait(IAsyncDisposable, Boolean)	Configures how awaits on the tasks returned from an async disposable will be performed.