Async load database encrypted bytes to memory while entering password

src/KeePassLib2Android/Serialization/KdbxFile.Read.cs

@@ -162,17 +162,6 @@ namespace KeePassLib.Serialization
 			finally { CommonCleanUpRead(sSource, hashedStream); }
 		}
 
-		public static void CopyStream(Stream input, Stream output)
-		{
-			byte[] buffer = new byte[4096];
-			int read;
-			while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
-			{
-				output.Write(buffer, 0, read);
-			}
-			output.Seek(0, SeekOrigin.Begin);
-		}
-
 		private void CommonCleanUpRead(Stream sSource, HashingStreamEx hashedStream)
 		{
 			hashedStream.Close();

src/Kp2aBusinessLogic/database/Database.cs

@@ -94,7 +94,7 @@ namespace keepass2android
 		}
 
 		
-		public void LoadData(IKp2aApp app, IOConnectionInfo iocInfo, String password, String keyfile, ProgressDialogStatusLogger status)
+		public void LoadData(IKp2aApp app, IOConnectionInfo iocInfo, MemoryStream databaseData, String password, String keyfile, ProgressDialogStatusLogger status)
 		{
 			PwDatabase pwDatabase = new PwDatabase();
 
@@ -113,10 +113,11 @@ namespace keepass2android
 				}
 			}
 
+			IFileStorage fileStorage = _app.GetFileStorage(iocInfo);
+			var filename = fileStorage.GetFilenameWithoutPathAndExt(iocInfo);
 			try
 			{
-				IFileStorage fileStorage = _app.GetFileStorage(iocInfo);
-				pwDatabase.Open(fileStorage.OpenFileForRead(iocInfo), fileStorage.GetFilenameWithoutPathAndExt(iocInfo), iocInfo, compositeKey, status);
+				pwDatabase.Open(databaseData, filename, iocInfo, compositeKey, status);
 			}
 			catch (Exception)
 			{
@@ -125,7 +126,8 @@ namespace keepass2android
 					//if we don't get a password, we don't know whether this means "empty password" or "no password"
 					//retry without password:
 					compositeKey.RemoveUserKey(compositeKey.GetUserKey(typeof (KcpPassword)));
-					pwDatabase.Open(iocInfo, compositeKey, status);
+					databaseData.Seek(0, SeekOrigin.Begin);
+					pwDatabase.Open(databaseData, filename, iocInfo, compositeKey, status);
 				}
 				else throw;
 			}

src/Kp2aBusinessLogic/database/edit/LoadDB.cs

@@ -16,21 +16,24 @@ This file is part of Keepass2Android, Copyright 2013 Philipp Crocoll. This file
   */
 
 using System;
+using System.IO;
 using KeePassLib.Serialization;
 
 namespace keepass2android
 {
 	public class LoadDb : RunnableOnFinish {
 		private readonly IOConnectionInfo _ioc;
+		private readonly MemoryStream _databaseData;
 		private readonly String _pass;
 		private readonly String _key;
 		private readonly IKp2aApp _app;
 		private readonly bool _rememberKeyfile;
 		
-		public LoadDb(IKp2aApp app, IOConnectionInfo ioc, String pass, String key, OnFinish finish): base(finish)
+		public LoadDb(IKp2aApp app, IOConnectionInfo ioc, MemoryStream databaseData, String pass, String key, OnFinish finish): base(finish)
 		{
 			_app = app;
 			_ioc = ioc;
+			_databaseData = databaseData;
 			_pass = pass;
 			_key = key;
 
@@ -44,7 +47,7 @@ namespace keepass2android
 			try
 			{
 				StatusLogger.UpdateMessage(UiStringKey.loading_database);
-				_app.GetDb().LoadData (_app, _ioc, _pass, _key, StatusLogger);
+				_app.GetDb().LoadData (_app, _ioc, _databaseData, _pass, _key, StatusLogger);
 				SaveFileData (_ioc, _key);
 				
 			} catch (KeyFileException) {

src/keepass2android/PasswordActivity.cs

@@ -16,6 +16,7 @@ This file is part of Keepass2Android, Copyright 2013 Philipp Crocoll. This file
   */
 
 using System;
+using System.Threading.Tasks;
 using Android.App;
 using Android.Content;
 using Android.OS;
@@ -29,6 +30,9 @@ using Android.Text;
 using Android.Content.PM;
 using KeePassLib.Keys;
 using KeePassLib.Serialization;
+using KeePassLib.Utility;
+
+using MemoryStream = System.IO.MemoryStream;
 
 namespace keepass2android
 {
@@ -331,6 +335,9 @@ namespace keepass2android
 				}
 			}
 
+			// Create task to kick off file loading while the user enters the password
+			var loadDbTask = new Task<MemoryStream>(LoadDbFile);
+
 			AppTask = AppTask.GetTaskInOnCreate(savedInstanceState, Intent);
 			
 			SetContentView(Resource.Layout.password);
@@ -364,7 +371,7 @@ namespace keepass2android
 				App.Kp2a.GetDb().QuickUnlockKeyLength = int.Parse(_prefs.GetString(GetString(Resource.String.QuickUnlockLength_key), GetString(Resource.String.QuickUnlockLength_default)));
 				
 				Handler handler = new Handler();
-				LoadDb task = new LoadDb(App.Kp2a, _ioConnection, pass, key, new AfterLoad(handler, this));
+				LoadDb task = new LoadDb(App.Kp2a, _ioConnection, loadDbTask.Result, pass, key, new AfterLoad(handler, this));
 				ProgressTask pt = new ProgressTask(App.Kp2a, this, task);
 				pt.Run();
 			};
@@ -439,7 +446,34 @@ namespace keepass2android
 			
 			RetrieveSettings();
 
+			loadDbTask.Start();
+		}
 
+		private MemoryStream LoadDbFile()
+		{
+			System.Diagnostics.Debug.WriteLine("LoadDbFile Started");
+			var fileStorage = App.Kp2a.GetFileStorage(_ioConnection);
+			var stream = fileStorage.OpenFileForRead(_ioConnection);
+
+			var memoryStream = stream as MemoryStream;
+			if (memoryStream == null)
+			{
+				// Read the file into memory
+				int capacity = 4096; // Default initial capacity, if stream can't report it.
+				if (stream.CanSeek)
+				{
+					capacity = (int)stream.Length;
+					System.Diagnostics.Debug.WriteLine("LoadDbFile, data size: " + capacity);
+				}
+				memoryStream = new MemoryStream(capacity);
+				MemUtil.CopyStream(stream, memoryStream);
+				stream.Close();
+				memoryStream.Seek(0, System.IO.SeekOrigin.Begin);
+			}
+
+			System.Diagnostics.Debug.WriteLine("LoadDbFile Done");
+
+			return memoryStream;
 		}
 
 		protected override void OnSaveInstanceState(Bundle outState)