BufferedReadStream.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / Net / Mail / BufferedReadStream.cs / 1 / BufferedReadStream.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Net 
{ 
    using System;
    using System.IO; 

    internal class BufferedReadStream : DelegatedStream
    {
        byte[] storedBuffer; 
        int storedLength;
        int storedOffset; 
        bool readMore; 

        internal BufferedReadStream(Stream stream) : this(stream, false) 
        {
        }

        internal BufferedReadStream(Stream stream, bool readMore) : base(stream) 
        {
            this.readMore = readMore; 
        } 

        public override bool CanWrite 
        {
            get
            {
                return false; 
            }
        } 
 
        public override bool CanSeek
        { 
            get
            {
                return false;
            } 
        }
 
        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state) 
        {
            ReadAsyncResult result = new ReadAsyncResult(this, callback, state); 
            result.Read(buffer, offset, count);
            return result;
        }
 
        public override int EndRead(IAsyncResult asyncResult)
        { 
            int read = ReadAsyncResult.End(asyncResult); 
            return read;
        } 

        public override int Read(byte[] buffer, int offset, int count)
        {
            int read = 0; 
            if (this.storedOffset < this.storedLength)
            { 
                read = Math.Min(count, this.storedLength - this.storedOffset); 
                Buffer.BlockCopy(this.storedBuffer, this.storedOffset, buffer, offset, read);
                this.storedOffset += read; 
                if (read == count || !this.readMore)
                {
                    return read;
                } 
                offset += read;
                count -= read; 
            } 
            return read + base.Read(buffer, offset, count);
        } 

        public override int ReadByte()
        {
            if (this.storedOffset < this.storedLength) 
            {
                return (int)this.storedBuffer[this.storedOffset++]; 
            } 
            else
            { 
                return base.ReadByte();
            }
        }
 

        internal void Push(byte[] buffer, int offset, int count) 
        { 
            if (count == 0)
                return; 

            if (this.storedOffset == this.storedLength)
            {
                if (this.storedBuffer == null || this.storedBuffer.Length < count) 
                {
                    this.storedBuffer = new byte[count]; 
                } 
                this.storedOffset = 0;
                this.storedLength = count; 
            }
            else
            {
                // if there's room to just insert before existing data 
                if (count <= this.storedOffset)
                { 
                    this.storedOffset -= count; 
                }
                // if there's room in the buffer but need to shift things over 
                else if (count <= this.storedBuffer.Length - this.storedLength + this.storedOffset)
                {
                    Buffer.BlockCopy(this.storedBuffer, this.storedOffset, this.storedBuffer, count, this.storedLength - this.storedOffset);
                    this.storedLength += count - this.storedOffset; 
                    this.storedOffset = 0;
                } 
                else 
                {
                    byte[] newBuffer = new byte[count + this.storedLength - this.storedOffset]; 
                    Buffer.BlockCopy(this.storedBuffer, this.storedOffset, newBuffer, count, this.storedLength - this.storedOffset);
                    this.storedLength += count - this.storedOffset;
                    this.storedOffset = 0;
                    this.storedBuffer = newBuffer; 
                }
            } 
            Buffer.BlockCopy(buffer, offset, this.storedBuffer, this.storedOffset, count); 
        }
 
        class ReadAsyncResult : LazyAsyncResult
        {
            BufferedReadStream parent;
            int read; 
            static AsyncCallback onRead = new AsyncCallback(OnRead);
 
            internal ReadAsyncResult(BufferedReadStream parent, AsyncCallback callback, object state) : base(null,state,callback) 
            {
                this.parent = parent; 
            }

            internal void Read(byte[] buffer, int offset, int count){
                if (parent.storedOffset < parent.storedLength) 
                {
                    this.read = Math.Min(count, parent.storedLength - parent.storedOffset); 
                    Buffer.BlockCopy(parent.storedBuffer, parent.storedOffset, buffer, offset, this.read); 
                    parent.storedOffset += this.read;
                    if (this.read == count || !this.parent.readMore) 
                    {
                        this.InvokeCallback();
                        return;
                    } 
                    count -= this.read;
                    offset += this.read; 
                } 
                IAsyncResult result = parent.BaseStream.BeginRead(buffer, offset, count, onRead, this);
                if (result.CompletedSynchronously) 
                {
                    //
                    this.read += parent.BaseStream.EndRead(result);
                    InvokeCallback(); 
                }
            } 
 
            internal static int End(IAsyncResult result)
            { 
                ReadAsyncResult thisPtr = (ReadAsyncResult)result;
                thisPtr.InternalWaitForCompletion();
                return thisPtr.read;
            } 

            static void OnRead(IAsyncResult result) 
            { 
                if (!result.CompletedSynchronously)
                { 
                    ReadAsyncResult thisPtr = (ReadAsyncResult)result.AsyncState;
                    try
                    {
                        thisPtr.read += thisPtr.parent.BaseStream.EndRead(result); 
                        thisPtr.InvokeCallback();
                    } 
                    catch (Exception e) 
                    {
                        if (thisPtr.IsCompleted) 
                            throw;
                        thisPtr.InvokeCallback(e);
                    }
                    catch { 
                        if (thisPtr.IsCompleted)
                            throw; 
                        thisPtr.InvokeCallback(new Exception(SR.GetString(SR.net_nonClsCompliantException))); 
                    }
                } 
            }
        }
    }
}

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