Add async support to SftpClient and SftpFileStream

src/Renci.SshNet/ISftpClient.cs

@@ -1030,7 +1030,7 @@ public interface ISftpClient
         /// </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>
+        /// <param name="createMode">Specifies how the file should be created.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
         /// <returns>A <see cref="Task"/> that represents the asynchronous upload operation.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="input" /> is <b>null</b>.</exception>
@@ -1042,7 +1042,7 @@ public interface ISftpClient
         /// <remarks>
         /// Method calls made by this method to <paramref name="input" />, may under certain conditions result in exceptions thrown by the stream.
         /// </remarks>
-        Task UploadFileAsync(Stream input, string path, bool canOverride, CancellationToken cancellationToken);
+        Task UploadFileAsync(Stream input, string path, UploadMode createMode, CancellationToken cancellationToken);
 #endif
 
         /// <summary>

src/Renci.SshNet/Sftp/ISftpSession.cs

@@ -55,6 +55,10 @@ internal interface ISftpSession : ISubsystemSession
         /// </returns>
         SftpFileAttributes RequestFStat(byte[] handle, bool nullOnError);
 
+#if FEATURE_TAP
+        Task<SftpFileAttributes> RequestFStatAsync(byte[] handle, CancellationToken cancellationToken);
+#endif
+
         /// <summary>
         /// Performs SSH_FXP_STAT request.
         /// </summary>

src/Renci.SshNet/Sftp/SftpFileStream.cs

@@ -382,12 +382,12 @@ internal static async Task<SftpFileStream> OpenAsync(ISftpSession session, strin
             {
                 try
                 {
-                    var attributes = session.RequestFStat(handle, false);  // ToDo: Async
+                    var attributes = await session.RequestFStatAsync(handle, cancellationToken).ConfigureAwait(false);
                     position = attributes.Size;
                 }
                 catch
                 {
-                    session.RequestClose(handle);  // ToDo: Async
+                    session.RequestClose(handle);
                     throw;
                 }
             }

src/Renci.SshNet/Sftp/SftpSession.cs

@@ -962,6 +962,24 @@ public SftpFileAttributes RequestFStat(byte[] handle, bool nullOnError)
             return attributes;
         }
 
+#if FEATURE_TAP
+        public async Task<SftpFileAttributes> RequestFStatAsync(byte[] handle, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            TaskCompletionSource<SftpFileAttributes> tcs = new TaskCompletionSource<SftpFileAttributes>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+            using (cancellationToken.Register((s) => ((TaskCompletionSource<SftpFileAttributes>)s).TrySetCanceled(), tcs, false))
+            {
+                SendRequest(new SftpFStatRequest(ProtocolVersion, NextRequestId, handle,
+                    response => tcs.TrySetResult(response.Attributes),
+                    response => tcs.TrySetException(GetSftpException(response))));
+
+                return await tcs.Task.ConfigureAwait(false);
+            }
+        }
+#endif
+
         /// <summary>
         /// Performs SSH_FXP_SETSTAT request.
         /// </summary>

src/Renci.SshNet/Sftp/UploadMode.cs

@@ -0,0 +1,23 @@
+namespace Renci.SshNet.Sftp
+{
+    /// <summary>
+    /// Specifies how the uploaded file should be created.
+    /// </summary>
+    public enum UploadMode
+    {
+        /// <summary>
+        /// A new file should be created. If the file already exists, an exception is thrown.
+        /// </summary>
+        CreateNew = 1,
+
+        /// <summary>
+        /// A new file should be created. If the file already exists, it will be overwritten.
+        /// </summary>
+        Overwrite = 2,
+
+        /// <summary>
+        /// Opens the file if it exists and seeks to the end of the file, or creates a new file.
+        /// </summary>
+        Append = 6
+    }
+}

src/Renci.SshNet/SftpClient.cs

@@ -964,7 +964,7 @@ public void UploadFile(Stream input, string path, bool canOverride, Action<ulong
         /// </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>
+        /// <param name="createMode">Specifies how the file should be created.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
         /// <returns>A <see cref="Task"/> that represents the asynchronous upload operation.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="input" /> is <b>null</b> -or- <paramref name="path" /> is <b>null</b>.</exception>
@@ -975,7 +975,7 @@ public void UploadFile(Stream input, string path, bool canOverride, Action<ulong
         /// <remarks>
         /// Method calls made by this method to <paramref name="input" />, may under certain conditions result in exceptions thrown by the stream.
         /// </remarks>
-        public async Task UploadFileAsync(Stream input, string path, bool canOverride, CancellationToken cancellationToken)
+        public async Task UploadFileAsync(Stream input, string path, UploadMode createMode, CancellationToken cancellationToken)
         {
             if (input == null)
                 throw new ArgumentNullException("input");
@@ -985,7 +985,7 @@ public async Task UploadFileAsync(Stream input, string path, bool canOverride, C
             CheckDisposedOrNotConnected();
             cancellationToken.ThrowIfCancellationRequested();
 
-            using (SftpFileStream output = await SftpFileStream.OpenAsync(_sftpSession, path, canOverride ? FileMode.Create : FileMode.CreateNew, FileAccess.Write, (int)_bufferSize, cancellationToken).ConfigureAwait(false))
+            using (SftpFileStream output = await SftpFileStream.OpenAsync(_sftpSession, path, (FileMode)createMode, FileAccess.Write, (int)_bufferSize, cancellationToken).ConfigureAwait(false))
             {
                 await input.CopyToAsync(output, (int)_sftpSession.CalculateOptimalWriteLength(_bufferSize, output.Handle), cancellationToken).ConfigureAwait(false);
             }