DelegatedStream.cs

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using System.IO;
using System.Threading;
using System.Threading.Tasks;
 
namespace System.Net;
 
internal abstract class DelegatedStream : Stream
{
    private readonly Stream _stream;
 
    protected Stream BaseStream => _stream;
 
    public override bool CanRead => _stream.CanRead;
 
    public override bool CanSeek => _stream.CanSeek;
 
    public override bool CanWrite => _stream.CanWrite;
 
    public override long Length
    {
        get
        {
            if (!CanSeek)
            {
                throw new NotSupportedException(System.SR.SeekNotSupported);
            }
            return _stream.Length;
        }
    }
 
    public override long Position
    {
        get
        {
            if (!CanSeek)
            {
                throw new NotSupportedException(System.SR.SeekNotSupported);
            }
            return _stream.Position;
        }
        set
        {
            if (!CanSeek)
            {
                throw new NotSupportedException(System.SR.SeekNotSupported);
            }
            _stream.Position = value;
        }
    }
 
    protected DelegatedStream(Stream stream)
    {
        if (stream == null)
        {
            throw new ArgumentNullException("stream");
        }
        _stream = stream;
    }
 
    public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
    {
        if (!CanRead)
        {
            throw new NotSupportedException(System.SR.ReadNotSupported);
        }
        return _stream.BeginRead(buffer, offset, count, callback, state);
    }
 
    public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
    {
        if (!CanWrite)
        {
            throw new NotSupportedException(System.SR.WriteNotSupported);
        }
        return _stream.BeginWrite(buffer, offset, count, callback, state);
    }
 
    public override void Close()
    {
        _stream.Close();
    }
 
    public override int EndRead(IAsyncResult asyncResult)
    {
        if (!CanRead)
        {
            throw new NotSupportedException(System.SR.ReadNotSupported);
        }
        return _stream.EndRead(asyncResult);
    }
 
    public override void EndWrite(IAsyncResult asyncResult)
    {
        if (!CanWrite)
        {
            throw new NotSupportedException(System.SR.WriteNotSupported);
        }
        _stream.EndWrite(asyncResult);
    }
 
    public override void Flush()
    {
        _stream.Flush();
    }
 
    public override Task FlushAsync(CancellationToken cancellationToken)
    {
        return _stream.FlushAsync(cancellationToken);
    }
 
    public override int Read(byte[] buffer, int offset, int count)
    {
        if (!CanRead)
        {
            throw new NotSupportedException(System.SR.ReadNotSupported);
        }
        return _stream.Read(buffer, offset, count);
    }
 
    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
    {
        if (!CanRead)
        {
            throw new NotSupportedException(System.SR.ReadNotSupported);
        }
        return _stream.ReadAsync(buffer, offset, count, cancellationToken);
    }
 
    public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken))
    {
        if (!CanRead)
        {
            throw new NotSupportedException(System.SR.ReadNotSupported);
        }
        return _stream.ReadAsync(buffer, cancellationToken);
    }
 
    public override long Seek(long offset, SeekOrigin origin)
    {
        if (!CanSeek)
        {
            throw new NotSupportedException(System.SR.SeekNotSupported);
        }
        return _stream.Seek(offset, origin);
    }
 
    public override void SetLength(long value)
    {
        if (!CanSeek)
        {
            throw new NotSupportedException(System.SR.SeekNotSupported);
        }
        _stream.SetLength(value);
    }
 
    public override void Write(byte[] buffer, int offset, int count)
    {
        if (!CanWrite)
        {
            throw new NotSupportedException(System.SR.WriteNotSupported);
        }
        _stream.Write(buffer, offset, count);
    }
 
    public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
    {
        if (!CanWrite)
        {
            throw new NotSupportedException(System.SR.WriteNotSupported);
        }
        return _stream.WriteAsync(buffer, offset, count, cancellationToken);
    }
 
    public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken))
    {
        if (!CanWrite)
        {
            throw new NotSupportedException(System.SR.WriteNotSupported);
        }
        return _stream.WriteAsync(buffer, cancellationToken);
    }
}