SSH.NET/Renci.SshClient/Renci.SshNet/SftpClient.cs

using System;
using System.Linq;
using System.Collections.Generic;
using System.IO;
using Renci.SshNet.Sftp;
using System.Text;
using Renci.SshNet.Common;
using System.Globalization;
using System.Threading;

namespace Renci.SshNet
{
    /// <summary>
    /// 
    /// </summary>
    public partial class SftpClient : BaseClient
    {
        /// <summary>
        /// Holds SftpSession instance that used to communicate to the SFTP server
        /// </summary>
        private SftpSession _sftpSession;

        /// <summary>
        /// Gets or sets the operation timeout.
        /// </summary>
        /// <value>The operation timeout.</value>
        public TimeSpan OperationTimeout { get; set; }

        /// <summary>
        /// Gets or sets the size of the buffer.
        /// </summary>
        /// <value>The size of the buffer.</value>
        public uint BufferSize { get; set; }

        /// <summary>
        /// Gets remote working directory.
        /// </summary>
        public string WorkingDirectory
        {
            get
            {
                if (this._sftpSession == null)
                    return null;
                return this._sftpSession.WorkingDirectory;
            }
        }

        /// <summary>
        /// Gets sftp protocol version.
        /// </summary>
        public int ProtocolVersion { get; private set; }

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="SftpClient"/> class.
        /// </summary>
        /// <param name="connectionInfo">The connection info.</param>
        /// <exception cref="ArgumentNullException"><paramref name="connectionInfo"/> is null.</exception>
        public SftpClient(ConnectionInfo connectionInfo)
            : base(connectionInfo)
        {
            this.OperationTimeout = new TimeSpan(0, 0, 0, 0, -1);
            this.BufferSize = 1024 * 32 - 38;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SftpClient"/> class.
        /// </summary>
        /// <param name="host">Connection host.</param>
        /// <param name="port">Connection port.</param>
        /// <param name="username">Authentication username.</param>
        /// <param name="password">Authentication password.</param>
        /// <exception cref="ArgumentNullException"><paramref name="password"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is null or contains whitespace characters.</exception>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="System.Net.IPEndPoint.MinPort"/> and <see cref="System.Net.IPEndPoint.MaxPort"/>.</exception>
        public SftpClient(string host, int port, string username, string password)
            : this(new PasswordConnectionInfo(host, port, username, password))
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SftpClient"/> class.
        /// </summary>
        /// <param name="host">Connection host.</param>
        /// <param name="username">Authentication username.</param>
        /// <param name="password">Authentication password.</param>
        /// <exception cref="ArgumentNullException"><paramref name="password"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is null or contains whitespace characters.</exception>
        public SftpClient(string host, string username, string password)
            : this(host, 22, username, password)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SftpClient"/> class.
        /// </summary>
        /// <param name="host">Connection host.</param>
        /// <param name="port">Connection port.</param>
        /// <param name="username">Authentication username.</param>
        /// <param name="keyFiles">Authentication private key file(s) .</param>
        /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, -or- <paramref name="username"/> is null or contains whitespace characters.</exception>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="System.Net.IPEndPoint.MinPort"/> and <see cref="System.Net.IPEndPoint.MaxPort"/>.</exception>
        public SftpClient(string host, int port, string username, params PrivateKeyFile[] keyFiles)
            : this(new PrivateKeyConnectionInfo(host, port, username, keyFiles))
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SftpClient"/> class.
        /// </summary>
        /// <param name="host">Connection host.</param>
        /// <param name="username">Authentication username.</param>
        /// <param name="keyFiles">Authentication private key file(s) .</param>
        /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, -or- <paramref name="username"/> is null or contains whitespace characters.</exception>
        public SftpClient(string host, string username, params PrivateKeyFile[] keyFiles)
            : this(host, 22, username, keyFiles)
        {
        }

        #endregion

        /// <summary>
        /// Changes remote directory to path.
        /// </summary>
        /// <param name="path">New directory path.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="SftpPermissionDeniedException">Permission to change directory denied by remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="SftpPathNotFoundException">The path in <paramref name="path"/> was not found on the remote host.</exception>
        /// <exception cref="SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void ChangeDirectory(string path)
        {
            if (path == null)
                throw new ArgumentNullException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            this._sftpSession.ChangeDirectory(path);
        }

        /// <summary>
        /// Changes permissions of file(s) to specified mode.
        /// </summary>
        /// <param name="path">File(s) path, may match multiple files.</param>
        /// <param name="mode">The mode.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="SftpPermissionDeniedException">Permission to change permission on the path(s) was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="SftpPathNotFoundException">The path in <paramref name="path"/> was not found on the remote host.</exception>
        /// <exception cref="SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void ChangePermissions(string path, short mode)
        {
            var file = this.Get(path);

            file.SetPermissions(mode);
        }

        /// <summary>
        /// Creates remote directory specified by path.
        /// </summary>
        /// <param name="path">Directory path to create.</param>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to create the directory was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void CreateDirectory(string path)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException(path);

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            this._sftpSession.RequestMkDir(fullPath);
        }

        /// <summary>
        /// Deletes remote directory specified by path.
        /// </summary>
        /// <param name="path">Directory to be deleted path.</param>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to delete the directory was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void DeleteDirectory(string path)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            this._sftpSession.RequestRmDir(fullPath);
        }

        /// <summary>
        /// Deletes remote file specified by path.
        /// </summary>
        /// <param name="path">File to be deleted path.</param>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to delete the file was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void DeleteFile(string path)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            this._sftpSession.RequestRemove(fullPath);
        }

        /// <summary>
        /// Renames remote file from old path to new path.
        /// </summary>
        /// <param name="oldPath">Path to the old file location.</param>
        /// <param name="newPath">Path to the new file location.</param>
        /// <exception cref="ArgumentNullException"><paramref name="oldPath"/> or <paramref name="newPath"/> is null.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to rename the file was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void RenameFile(string oldPath, string newPath)
        {
            if (oldPath == null)
                throw new ArgumentNullException("oldPath");

            if (newPath == null)
                throw new ArgumentNullException("newPath");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var oldFullPath = this._sftpSession.GetCanonicalPath(oldPath);

            var newFullPath = this._sftpSession.GetCanonicalPath(newPath);

            this._sftpSession.RequestRename(oldFullPath, newFullPath);
        }

        /// <summary>
        /// Creates a symbolic link from old path to new path.
        /// </summary>
        /// <param name="path">The old path.</param>
        /// <param name="linkPath">The new path.</param>
        /// <exception cref="ArgumentException"><paramref name="path"/> or <paramref name="linkPath"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to create the symbolic link was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public void SymbolicLink(string path, string linkPath)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            if (linkPath.IsNullOrWhiteSpace())
                throw new ArgumentException("linkPath");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            var linkFullPath = this._sftpSession.GetCanonicalPath(linkPath);

            this._sftpSession.RequestSymLink(fullPath, linkFullPath);
        }

        /// <summary>
        /// Retrieves list of files in remote directory.
        /// </summary>
        /// <param name="path">The path.</param>
        /// <returns>List of directory entries</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to list the contents of the directory was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public IEnumerable<SftpFile> ListDirectory(string path)
        {
            return InternalListDirectory(path, null);
        }

        /// <summary>
        /// Begins an asynchronous operation of retrieving list of files in remote directory.
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="asyncCallback">The method to be called when the asynchronous write operation is completed.</param>
        /// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests.</param>
        /// <returns>
        /// An <see cref="IAsyncResult"/> that references the asynchronous operation.
        /// </returns>
        public IAsyncResult BeginListDirectory(string path, AsyncCallback asyncCallback, object state)
        {
            var asyncResult = new SftpListDirectoryAsyncResult(asyncCallback, state);

            this.ExecuteThread(() =>
            {
                try
                {
                    var result = this.InternalListDirectory(path, asyncResult);

                    asyncResult.SetAsCompleted(result, false);
                }
                catch (Exception exp)
                {
                    asyncResult.SetAsCompleted(exp, false);
                }
            });

            return asyncResult;
        }

        /// <summary>
        /// Ends an asynchronous operation of retrieving list of files in remote directory.
        /// </summary>
        /// <param name="asyncResult">The pending asynchronous SFTP request.</param>
        /// <returns>
        /// List of files
        /// </returns>
        /// <exception cref="ArgumentException">Either the IAsyncResult object (<paramref name="asyncResult"/>) did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.</exception>
        public IEnumerable<SftpFile> EndListDirectory(IAsyncResult asyncResult)
        {
            var ar = asyncResult as SftpListDirectoryAsyncResult;

            if (ar == null || ar.EndInvokeCalled)
                throw new ArgumentException("Either the IAsyncResult object did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.");

            // Wait for operation to complete, then return result or throw exception
            return ar.EndInvoke();
        }

        /// <summary>
        /// Gets reference to remote file or directory.
        /// </summary>
        /// <param name="path">The path.</param>
        /// <returns></returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFile Get(string path)
        {
            if (path == null)
                throw new ArgumentNullException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            var attributes = this._sftpSession.RequestLStat(fullPath);

            return new SftpFile(this._sftpSession, fullPath, attributes);
        }

        /// <summary>
        /// Checks whether file pr directory exists;
        /// </summary>
        /// <param name="path">The path.</param>
        /// <returns><c>true</c> if directory or file exists; otherwise <c>false</c>.</returns>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to perform the operation was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        public bool Exists(string path)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            //  Try to open as a file
            var handle = this._sftpSession.RequestOpen(fullPath, Flags.Read, true);

            if (handle == null)
            {
                handle = this._sftpSession.RequestOpenDir(fullPath, true);
            }

            if (handle == null)
            {
                return false;
            }
            else
            {
                this._sftpSession.RequestClose(handle);
                return true;
            }
        }

        /// <summary>
        /// Downloads remote file specified by the path into the stream.
        /// </summary>
        /// <param name="path">File to download.</param>
        /// <param name="output">Stream to write the file into.</param>
        /// <exception cref="ArgumentNullException"><paramref name="output"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to perform the operation was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        /// <remarks>Method calls made by this method to <paramref name="output"/>, may under certain conditions result in exceptions thrown by the stream.</remarks>
        public void DownloadFile(string path, Stream output)
        {
            this.InternalDownloadFile(path, output, null);
        }

        /// <summary>
        /// Begins an asynchronous file downloading into the stream.
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="output">The output.</param>
        /// <param name="asyncCallback">The method to be called when the asynchronous write operation is completed.</param>
        /// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests.</param>
        /// <returns>An <see cref="IAsyncResult"/> that references the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="output"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to perform the operation was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        /// <remarks>Method calls made by this method to <paramref name="output"/>, may under certain conditions result in exceptions thrown by the stream.</remarks>
        public IAsyncResult BeginDownloadFile(string path, Stream output, AsyncCallback asyncCallback, object state)
        {
            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            if (output == null)
                throw new ArgumentNullException("output");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var asyncResult = new SftpDownloadAsyncResult(asyncCallback, state);

            this.ExecuteThread(() =>
            {
                try
                {
                    this.InternalDownloadFile(path, output, asyncResult);

                    asyncResult.SetAsCompleted(null, false);
                }
                catch (Exception exp)
                {
                    asyncResult.SetAsCompleted(exp, false);
                }
            });

            return asyncResult;
        }

        /// <summary>
        /// Ends an asynchronous file downloading into the stream.
        /// </summary>
        /// <param name="asyncResult">The pending asynchronous SFTP request.</param>
        /// <exception cref="ArgumentException">Either the IAsyncResult object (<paramref name="asyncResult"/>) did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.</exception>
        public void EndDownloadFile(IAsyncResult asyncResult)
        {
            var ar = asyncResult as SftpDownloadAsyncResult;

            if (ar == null || ar.EndInvokeCalled)
                throw new ArgumentException("Either the IAsyncResult object did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.");

            // Wait for operation to complete, then return result or throw exception
            ar.EndInvoke();
        }

        /// <summary>
        /// Uploads stream into remote file..
        /// </summary>
        /// <param name="input">Data input stream.</param>
        /// <param name="path">Remote file path.</param>
        /// <exception cref="ArgumentNullException"><paramref name="input"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to upload the file was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        /// <remarks>Method calls made by this method to <paramref name="input"/>, may under certain conditions result in exceptions thrown by the stream.</remarks>
        public void UploadFile(Stream input, string path)
        {
            this.UploadFile(input, path, true);
        }

        /// <summary>
        /// Uploads stream into remote file..
        /// </summary>
        /// <param name="input">Data input stream.</param>
        /// <param name="path">Remote file path.</param>
        /// <param name="canOverride">if set to <c>true</c> then existing file will be overwritten.</param>
        /// <exception cref="ArgumentNullException"><paramref name="input"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to upload the file was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        /// <remarks>
        /// Method calls made by this method to <paramref name="input"/>, may under certain conditions result in exceptions thrown by the stream.
        /// </remarks>
        public void UploadFile(Stream input, string path, bool canOverride)
        {
            var flags = Flags.Write | Flags.Truncate;

            if (canOverride)
                flags |= Flags.CreateNewOrOpen;
            else
                flags |= Flags.CreateNew;

            this.InternalUploadFile(input, path, null, flags);
        }

        /// <summary>
        /// Begins an asynchronous uploading the steam into remote file.
        /// </summary>
        /// <param name="input">Data input stream.</param>
        /// <param name="path">Remote file path.</param>
        /// <param name="asyncCallback">The method to be called when the asynchronous write operation is completed.</param>
        /// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests.</param>
        /// <returns>An <see cref="IAsyncResult"/> that references the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="input"/> is null.</exception>
        /// <exception cref="ArgumentException"><paramref name="path"/> is null or contains whitespace characters.</exception>
        /// <exception cref="SshConnectionException">Client is not connected.</exception>
        /// <exception cref="Renci.SshNet.Common.SftpPermissionDeniedException">Permission to list the contents of the directory was denied by the remote host -or- a SSH command was denied by the server.</exception>
        /// <exception cref="Renci.SshNet.Common.SshException">A SSH error where <see cref="P:SshException.Message"/> is the message from the remote host.</exception>
        /// <remarks>Method calls made by this method to <paramref name="input"/>, may under certain conditions result in exceptions thrown by the stream.</remarks>
        public IAsyncResult BeginUploadFile(Stream input, string path, AsyncCallback asyncCallback, object state)
        {
            if (input == null)
                throw new ArgumentNullException("input");

            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var asyncResult = new SftpUploadAsyncResult(asyncCallback, state);

            this.ExecuteThread(() =>
            {
                try
                {
                    this.InternalUploadFile(input, path, asyncResult, Flags.Write | Flags.CreateNewOrOpen | Flags.Truncate);

                    asyncResult.SetAsCompleted(null, false);
                }
                catch (Exception exp)
                {
                    asyncResult.SetAsCompleted(exp, false);
                }
            });

            return asyncResult;
        }

        /// <summary>
        /// Ends an asynchronous uploading the steam into remote file.
        /// </summary>
        /// <param name="asyncResult">The pending asynchronous SFTP request.</param>
        /// <exception cref="ArgumentException">Either the IAsyncResult object (<paramref name="asyncResult"/>) did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.</exception>
        public void EndUploadFile(IAsyncResult asyncResult)
        {
            var ar = asyncResult as SftpUploadAsyncResult;

            if (ar == null || ar.EndInvokeCalled)
                throw new ArgumentException("Either the IAsyncResult object did not come from the corresponding async method on this type, or EndExecute was called multiple times with the same IAsyncResult.");

            // Wait for operation to complete, then return result or throw exception
            ar.EndInvoke();
        }

        #region File Methods

        /// <summary>
        /// Appends lines to a file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to append the lines to. The file is created if it does not already exist.</param>
        /// <param name="contents">The lines to append to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> or <paramref name="contents"/> is null.</exception>
        public void AppendAllLines(string path, IEnumerable<string> contents)
        {
            if (contents == null)
                throw new ArgumentNullException("contents");

            using (var stream = this.AppendText(path))
            {
                foreach (var line in contents)
                {
                    stream.WriteLine(line);
                }
            }
        }

        /// <summary>
        /// Appends lines to a file by using a specified encoding, and then closes the file.
        /// </summary>
        /// <param name="path">The file to append the lines to. The file is created if it does not already exist.</param>
        /// <param name="contents">The lines to append to the file.</param>
        /// <param name="encoding">The character encoding to use.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/>, <paramref name="contents"/> or <paramref name="encoding"/> is null.</exception>
        public void AppendAllLines(string path, IEnumerable<string> contents, Encoding encoding)
        {
            if (contents == null)
                throw new ArgumentNullException("contents");

            using (var stream = this.AppendText(path, encoding))
            {
                foreach (var line in contents)
                {
                    stream.WriteLine(line);
                }
            }
        }

        /// <summary>
        ///  Opens a file, appends the specified string to the file, and then closes the file. 
        ///  If the file does not exist, this method creates a file, writes the specified string to the file, then closes the file.
        /// </summary>
        /// <param name="path">The file to append the specified string to.</param>
        /// <param name="contents">The string to append to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> or <paramref name="contents"/> is null.</exception>
        public void AppendAllText(string path, string contents)
        {
            using (var stream = this.AppendText(path))
            {
                stream.Write(contents);
            }
        }

        /// <summary>
        /// Opens a file, appends the specified string to the file, and then closes the file.
        /// If the file does not exist, this method creates a file, writes the specified string to the file, then closes the file.
        /// </summary>
        /// <param name="path">The file to append the specified string to.</param>
        /// <param name="contents">The string to append to the file.</param>
        /// <param name="encoding">The character encoding to use.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/>, <paramref name="contents"/> or <paramref name="encoding"/> is null.</exception>
        public void AppendAllText(string path, string contents, Encoding encoding)
        {
            using (var stream = this.AppendText(path, encoding))
            {
                stream.Write(contents);
            }
        }

        /// <summary>
        /// Creates a <see cref="System.IO.StreamWriter"/> that appends UTF-8 encoded text to an existing file.
        /// </summary>
        /// <param name="path">The path to the file to append to.</param>
        /// <returns>A StreamWriter that appends UTF-8 encoded text to an existing file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public StreamWriter AppendText(string path)
        {
            return this.AppendText(path, Encoding.UTF8);
        }

        /// <summary>
        /// Creates a <see cref="System.IO.StreamWriter"/> that appends UTF-8 encoded text to an existing file.
        /// </summary>
        /// <param name="path">The path to the file to append to.</param>
        /// <param name="encoding">The character encoding to use.</param>
        /// <returns>
        /// A StreamWriter that appends UTF-8 encoded text to an existing file.
        /// </returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> or <paramref name="encoding"/> is null.</exception>
        public StreamWriter AppendText(string path, Encoding encoding)
        {
            if (encoding == null)
                throw new ArgumentNullException("encoding");

            return new StreamWriter(new SftpFileStream(this._sftpSession, path, FileMode.Append, FileAccess.Write), encoding);
        }

        /// <summary>
        /// Creates or overwrites a file in the specified path.
        /// </summary>
        /// <param name="path">The path and name of the file to create.</param>
        /// <returns>A <see cref="SftpFileStream"/> that provides read/write access to the file specified in path</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream Create(string path)
        {
            return new SftpFileStream(this._sftpSession, path, FileMode.Create, FileAccess.ReadWrite);
        }

        /// <summary>
        /// Creates or overwrites the specified file.
        /// </summary>
        /// <param name="path">The path and name of the file to create.</param>
        /// <param name="bufferSize">The number of bytes buffered for reads and writes to the file.</param>
        /// <returns>A <see cref="SftpFileStream"/> that provides read/write access to the file specified in path</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream Create(string path, int bufferSize)
        {
            return new SftpFileStream(this._sftpSession, path, FileMode.Create, FileAccess.ReadWrite, bufferSize);
        }

        /// <summary>
        /// Creates or opens a file for writing UTF-8 encoded text.
        /// </summary>
        /// <param name="path">The file to be opened for writing.</param>
        /// <returns>A <see cref="System.IO.StreamWriter"/> that writes to the specified file using UTF-8 encoding.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public StreamWriter CreateText(string path)
        {
            return new StreamWriter(this.OpenWrite(path), Encoding.UTF8);
        }

        /// <summary>
        /// Creates or opens a file for writing UTF-8 encoded text.
        /// </summary>
        /// <param name="path">The file to be opened for writing.</param>
        /// <param name="encoding">The character encoding to use.</param>
        /// <returns> A <see cref="System.IO.StreamWriter"/> that writes to the specified file using UTF-8 encoding. </returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public StreamWriter CreateText(string path, Encoding encoding)
        {
            return new StreamWriter(this.OpenWrite(path), encoding);
        }

        /// <summary>
        /// Deletes the specified file or directory. An exception is not thrown if the specified file does not exist.
        /// </summary>
        /// <param name="path">The name of the file or directory to be deleted. Wildcard characters are not supported.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void Delete(string path)
        {
            var file = this.Get(path);

            file.Delete();
        }

        /// <summary>
        /// Returns the date and time the specified file or directory was last accessed.
        /// </summary>
        /// <param name="path">The file or directory for which to obtain access date and time information.</param>
        /// <returns>A <see cref="System.DateTime"/> structure set to the date and time that the specified file or directory was last accessed. This value is expressed in local time.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public DateTime GetLastAccessTime(string path)
        {
            var file = this.Get(path);

            return file.LastAccessTime;
        }

        /// <summary>
        /// Returns the date and time, in coordinated universal time (UTC), that the specified file or directory was last accessed.
        /// </summary>
        /// <param name="path">The file or directory for which to obtain access date and time information.</param>
        /// <returns>A <see cref="System.DateTime"/> structure set to the date and time that the specified file or directory was last accessed. This value is expressed in UTC time.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public DateTime GetLastAccessTimeUtc(string path)
        {
            var file = this.Get(path);

            return file.LastAccessTime.ToUniversalTime();
        }

        /// <summary>
        /// Returns the date and time the specified file or directory was last written to.
        /// </summary>
        /// <param name="path">The file or directory for which to obtain write date and time information.</param>
        /// <returns>A <see cref="System.DateTime"/> structure set to the date and time that the specified file or directory was last written to. This value is expressed in local time.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public DateTime GetLastWriteTime(string path)
        {
            var file = this.Get(path);

            return file.LastWriteTime;
        }

        /// <summary>
        /// Returns the date and time, in coordinated universal time (UTC), that the specified file or directory was last written to.
        /// </summary>
        /// <param name="path">The file or directory for which to obtain write date and time information.</param>
        /// <returns>A <see cref="System.DateTime"/> structure set to the date and time that the specified file or directory was last written to. This value is expressed in UTC time.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public DateTime GetLastWriteTimeUtc(string path)
        {
            var file = this.Get(path);

            return file.LastWriteTime.ToUniversalTime();
        }

        /// <summary>
        /// Opens a <see cref="SftpFileStream"/> on the specified path with read/write access.
        /// </summary>
        /// <param name="path">The file to open.</param>
        /// <param name="mode">A <see cref="System.IO.FileMode"/> value that specifies whether a file is created if one does not exist, and determines whether the contents of existing files are retained or overwritten.</param>
        /// <returns>An unshared <see cref="SftpFileStream"/> that provides access to the specified file, with the specified mode and access.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream Open(string path, FileMode mode)
        {
            return new SftpFileStream(this._sftpSession, path, mode, FileAccess.ReadWrite);
        }

        /// <summary>
        /// Opens a <see cref="SftpFileStream"/> on the specified path, with the specified mode and access.
        /// </summary>
        /// <param name="path">The file to open.</param>
        /// <param name="mode">A <see cref="System.IO.FileMode"/> value that specifies whether a file is created if one does not exist, and determines whether the contents of existing files are retained or overwritten.</param>
        /// <param name="access">A <see cref="System.IO.FileAccess"/> value that specifies the operations that can be performed on the file.</param>
        /// <returns>An unshared <see cref="SftpFileStream"/> that provides access to the specified file, with the specified mode and access.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream Open(string path, FileMode mode, FileAccess access)
        {
            return new SftpFileStream(this._sftpSession, path, mode, access);
        }

        /// <summary>
        /// Opens an existing file for reading.
        /// </summary>
        /// <param name="path">The file to be opened for reading.</param>
        /// <returns>A read-only System.IO.FileStream on the specified path.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream OpenRead(string path)
        {
            return new SftpFileStream(this._sftpSession, path, FileMode.Open, FileAccess.Read);
        }

        /// <summary>
        /// Opens an existing UTF-8 encoded text file for reading.
        /// </summary>
        /// <param name="path">The file to be opened for reading.</param>
        /// <returns>A <see cref="System.IO.StreamReader"/> on the specified path.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public StreamReader OpenText(string path)
        {
            return new StreamReader(this.OpenRead(path), Encoding.UTF8);
        }

        /// <summary>
        /// Opens an existing file for writing.
        /// </summary>
        /// <param name="path">The file to be opened for writing.</param>
        /// <returns>An unshared <see cref="SftpFileStream"/> object on the specified path with <see cref="System.IO.FileAccess.Write"/> access.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileStream OpenWrite(string path)
        {
            return new SftpFileStream(this._sftpSession, path, FileMode.OpenOrCreate, FileAccess.Write);
        }

        /// <summary>
        /// Opens a binary file, reads the contents of the file into a byte array, and then closes the file.
        /// </summary>
        /// <param name="path">The file to open for reading.</param>
        /// <returns>A byte array containing the contents of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public byte[] ReadAllBytes(string path)
        {
            using (var stream = this.OpenRead(path))
            {
                var buffer = new byte[stream.Length];
                stream.Read(buffer, 0, buffer.Length);
                return buffer;
            }
        }

        /// <summary>
        /// Opens a text file, reads all lines of the file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to open for reading.</param>
        /// <returns>A string array containing all lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public string[] ReadAllLines(string path)
        {
            return this.ReadAllLines(path, Encoding.UTF8);
        }

        /// <summary>
        /// Opens a file, reads all lines of the file with the specified encoding, and then closes the file.
        /// </summary>
        /// <param name="path">The file to open for reading.</param>
        /// <param name="encoding">The encoding applied to the contents of the file.</param>
        /// <returns>A string array containing all lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public string[] ReadAllLines(string path, Encoding encoding)
        {
            var lines = new List<string>();
            using (var stream = new StreamReader(this.OpenRead(path), encoding))
            {
                while (!stream.EndOfStream)
                {
                    lines.Add(stream.ReadLine());
                }
            }
            return lines.ToArray();
        }

        /// <summary>
        /// Opens a text file, reads all lines of the file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to open for reading.</param>
        /// <returns>A string containing all lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public string ReadAllText(string path)
        {
            return this.ReadAllText(path, Encoding.UTF8);
        }

        /// <summary>
        /// Opens a file, reads all lines of the file with the specified encoding, and then closes the file.
        /// </summary>
        /// <param name="path">The file to open for reading.</param>
        /// <param name="encoding">The encoding applied to the contents of the file.</param>
        /// <returns>A string containing all lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public string ReadAllText(string path, Encoding encoding)
        {
            var lines = new List<string>();
            using (var stream = new StreamReader(this.OpenRead(path), encoding))
            {
                return stream.ReadToEnd();
            }
        }

        /// <summary>
        /// Reads the lines of a file.
        /// </summary>
        /// <param name="path">The file to read.</param>
        /// <returns>The lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public IEnumerable<string> ReadLines(string path)
        {
            return this.ReadAllLines(path);
        }

        /// <summary>
        /// Read the lines of a file that has a specified encoding.
        /// </summary>
        /// <param name="path">The file to read.</param>
        /// <param name="encoding">The encoding that is applied to the contents of the file.</param>
        /// <returns>The lines of the file.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public IEnumerable<string> ReadLines(string path, Encoding encoding)
        {
            return this.ReadAllLines(path, encoding);
        }

        /// <summary>
        /// Sets the date and time the specified file was last accessed.
        /// </summary>
        /// <param name="path">The file for which to set the access date and time information.</param>
        /// <param name="lastAccessTime">A <see cref="System.DateTime"/> containing the value to set for the last access date and time of path. This value is expressed in local time.</param>
        [Obsolete("Note: This method currently throws NotImplementedException because it has not yet been implemented.")]
        public void SetLastAccessTime(string path, DateTime lastAccessTime)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Sets the date and time, in coordinated universal time (UTC), that the specified file was last accessed.
        /// </summary>
        /// <param name="path">The file for which to set the access date and time information.</param>
        /// <param name="lastAccessTimeUtc">A <see cref="System.DateTime"/> containing the value to set for the last access date and time of path. This value is expressed in UTC time.</param>
        [Obsolete("Note: This method currently throws NotImplementedException because it has not yet been implemented.")]
        public void SetLastAccessTimeUtc(string path, DateTime lastAccessTimeUtc)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Sets the date and time that the specified file was last written to.
        /// </summary>
        /// <param name="path">The file for which to set the date and time information.</param>
        /// <param name="lastWriteTime">A System.DateTime containing the value to set for the last write date and time of path. This value is expressed in local time.</param>
        [Obsolete("Note: This method currently throws NotImplementedException because it has not yet been implemented.")]
        public void SetLastWriteTime(string path, DateTime lastWriteTime)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Sets the date and time, in coordinated universal time (UTC), that the specified file was last written to.
        /// </summary>
        /// <param name="path">The file for which to set the date and time information.</param>
        /// <param name="lastWriteTimeUtc">A System.DateTime containing the value to set for the last write date and time of path. This value is expressed in UTC time.</param>
        [Obsolete("Note: This method currently throws NotImplementedException because it has not yet been implemented.")]
        public void SetLastWriteTimeUtc(string path, DateTime lastWriteTimeUtc)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// Creates a new file, writes the specified byte array to the file, and then closes the file. If the target file already exists, it is overwritten.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="bytes">The bytes to write to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllBytes(string path, byte[] bytes)
        {
            using (var stream = this.OpenWrite(path))
            {
                stream.Write(bytes, 0, bytes.Length);
            }
        }

        /// <summary>
        /// Creates a new file, writes a collection of strings to the file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The lines to write to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllLines(string path, IEnumerable<string> contents)
        {
            this.WriteAllLines(path, contents, Encoding.UTF8);
        }

        /// <summary>
        /// Creates a new file, write the specified string array to the file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The string array to write to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllLines(string path, string[] contents)
        {
            this.WriteAllLines(path, contents, Encoding.UTF8);
        }

        /// <summary>
        /// Creates a new file by using the specified encoding, writes a collection of strings to the file, and then closes the file.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The lines to write to the file.</param>
        /// <param name="encoding">The character encoding to use.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllLines(string path, IEnumerable<string> contents, Encoding encoding)
        {
            using (var stream = this.CreateText(path, encoding))
            {
                foreach (var line in contents)
                {
                    stream.WriteLine(line);
                }
            }
        }

        /// <summary>
        /// Creates a new file, writes the specified string array to the file by using the specified encoding, and then closes the file.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The string array to write to the file.</param>
        /// <param name="encoding">An <see cref="System.Text.Encoding"/> object that represents the character encoding applied to the string array.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllLines(string path, string[] contents, Encoding encoding)
        {
            using (var stream = this.CreateText(path, encoding))
            {
                foreach (var line in contents)
                {
                    stream.WriteLine(line);
                }
            }
        }

        /// <summary>
        /// Creates a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is overwritten.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The string to write to the file.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllText(string path, string contents)
        {
            using (var stream = this.CreateText(path))
            {
                stream.Write(contents);
            }
        }

        /// <summary>
        /// Creates a new file, writes the specified string to the file using the specified encoding, and then closes the file. If the target file already exists, it is overwritten.
        /// </summary>
        /// <param name="path">The file to write to.</param>
        /// <param name="contents">The string to write to the file.</param>
        /// <param name="encoding">The encoding to apply to the string.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void WriteAllText(string path, string contents, Encoding encoding)
        {
            using (var stream = this.CreateText(path, encoding))
            {
                stream.Write(contents);
            }
        }

        /// <summary>
        /// Gets the <see cref="SftpFileAttributes"/> of the file on the path.
        /// </summary>
        /// <param name="path">The path to the file.</param>
        /// <returns>The <see cref="SftpFileAttributes"/> of the file on the path.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public SftpFileAttributes GetAttributes(string path)
        {
            var fullPath = this._sftpSession.GetCanonicalPath(path);

            return this._sftpSession.RequestLStat(fullPath);
        }

        /// <summary>
        /// Sets the specified <see cref="SftpFileAttributes"/> of the file on the specified path.
        /// </summary>
        /// <param name="path">The path to the file.</param>
        /// <param name="fileAttributes">The desired <see cref="SftpFileAttributes"/>.</param>
        /// <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        public void SetAttributes(string path, SftpFileAttributes fileAttributes)
        {
            var fullPath = this._sftpSession.GetCanonicalPath(path);

            this._sftpSession.RequestSetStat(fullPath, fileAttributes);
        }

        // Please don't forget this when you implement these methods: <exception cref="ArgumentNullException"><paramref name="path"/> is null.</exception>
        //public FileSecurity GetAccessControl(string path);
        //public FileSecurity GetAccessControl(string path, AccessControlSections includeSections);
        //public DateTime GetCreationTime(string path);
        //public DateTime GetCreationTimeUtc(string path);
        //public void SetAccessControl(string path, FileSecurity fileSecurity);
        //public void SetCreationTime(string path, DateTime creationTime);
        //public void SetCreationTimeUtc(string path, DateTime creationTimeUtc);

        #endregion

        private IEnumerable<SftpFile> InternalListDirectory(string path, SftpListDirectoryAsyncResult asynchResult)
        {
            if (path == null)
                throw new ArgumentNullException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            var handle = this._sftpSession.RequestOpenDir(fullPath);

            var basePath = fullPath;

            if (!basePath.EndsWith("/"))
                basePath = string.Format("{0}/", fullPath);

            var result = new List<SftpFile>();

            var files = this._sftpSession.RequestReadDir(handle);

            while (files != null)
            {
                result.AddRange(from f in files
                                select new SftpFile(this._sftpSession, string.Format(CultureInfo.InvariantCulture, "{0}{1}", basePath, f.Key), f.Value));

                if (asynchResult != null)
                {
                    asynchResult.Update(result.Count);
                }

                files = this._sftpSession.RequestReadDir(handle);
            }

            this._sftpSession.RequestClose(handle);

            return result;
        }

        private void InternalDownloadFile(string path, Stream output, SftpDownloadAsyncResult asynchResult)
        {
            if (output == null)
                throw new ArgumentNullException("output");

            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            var handle = this._sftpSession.RequestOpen(fullPath, Flags.Read);

            ulong offset = 0;

            var data = this._sftpSession.RequestRead(handle, offset, this.BufferSize);

            //  Read data while available
            while (data.Length > 0)
            {
                output.Write(data, 0, data.Length);

                output.Flush();

                offset += (ulong)data.Length;

                //  Call callback to report number of bytes read
                if (asynchResult != null)
                {
                    asynchResult.Update(offset);
                }

                data = this._sftpSession.RequestRead(handle, offset, this.BufferSize);
            }

            this._sftpSession.RequestClose(handle);
        }

        private void InternalUploadFile(Stream input, string path, SftpUploadAsyncResult asynchResult, Flags flags)
        {
            if (input == null)
                throw new ArgumentNullException("input");

            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            //  Ensure that connection is established.
            this.EnsureConnection();

            var fullPath = this._sftpSession.GetCanonicalPath(path);

            var handle = this._sftpSession.RequestOpen(fullPath, flags);

            ulong offset = 0;

            var buffer = new byte[this.BufferSize];

            var uploadCompleted = false;

            do
            {
                var bytesRead = input.Read(buffer, 0, buffer.Length);

                if (bytesRead < this.BufferSize)
                {
                    var data = new byte[bytesRead];
                    Buffer.BlockCopy(buffer, 0, data, 0, bytesRead); 
                    using (var wait = new AutoResetEvent(false))
                    {
                        this._sftpSession.RequestWrite(handle, offset, data, wait);
                    }
                    uploadCompleted = true;
                }
                else
                {
                    this._sftpSession.RequestWrite(handle, offset, buffer, null);
                }

                offset += (uint)bytesRead;

                //  Call callback to report number of bytes read
                if (asynchResult != null)
                {
                    asynchResult.Update(offset);
                }

            } while (!uploadCompleted);

            this._sftpSession.RequestClose(handle);
        }

        partial void ExecuteThread(Action action);

        /// <summary>
        /// Called when client is connected to the server.
        /// </summary>
        protected override void OnConnected()
        {
            base.OnConnected();

            this._sftpSession = new SftpSession(this.Session, this.OperationTimeout);

            this._sftpSession.Connect();

            //  Resolve current running version
            this.ProtocolVersion = this._sftpSession.ProtocolVersion;
        }

        /// <summary>
        /// Called when client is disconnecting from the server.
        /// </summary>
        protected override void OnDisconnecting()
        {
            base.OnDisconnecting();

            this._sftpSession.Disconnect();
        }

        /// <summary>
        /// Releases unmanaged and - optionally - managed resources
        /// </summary>
        /// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged ResourceMessages.</param>
        protected override void Dispose(bool disposing)
        {
            if (this._sftpSession != null)
            {
                this._sftpSession.Dispose();
                this._sftpSession = null;
            }

            base.Dispose(disposing);
        }
    }
}