Added new filesystem layer for read/write alignment with boundary of encrypted chunks.

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/BlockAlignedFile.java

@@ -0,0 +1,27 @@
+package org.cryptomator.filesystem.blockaligned;
+
+import java.io.UncheckedIOException;
+
+import org.cryptomator.filesystem.File;
+import org.cryptomator.filesystem.delegating.DelegatingFile;
+
+class BlockAlignedFile extends DelegatingFile<BlockAlignedReadableFile, BlockAlignedWritableFile, BlockAlignedFolder> {
+
+	private final int blockSize;
+
+	public BlockAlignedFile(BlockAlignedFolder parent, File delegate, int blockSize) {
+		super(parent, delegate);
+		this.blockSize = blockSize;
+	}
+
+	@Override
+	public BlockAlignedReadableFile openReadable() throws UncheckedIOException {
+		return new BlockAlignedReadableFile(delegate.openReadable(), blockSize);
+	}
+
+	@Override
+	public BlockAlignedWritableFile openWritable() throws UncheckedIOException {
+		return new BlockAlignedWritableFile(delegate.openWritable(), blockSize);
+	}
+
+}

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/BlockAlignedFileSystem.java

@@ -0,0 +1,12 @@
+package org.cryptomator.filesystem.blockaligned;
+
+import org.cryptomator.filesystem.FileSystem;
+import org.cryptomator.filesystem.Folder;
+
+public class BlockAlignedFileSystem extends BlockAlignedFolder implements FileSystem {
+
+	public BlockAlignedFileSystem(Folder delegate, int blockSize) {
+		super(null, delegate, blockSize);
+	}
+
+}

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/BlockAlignedFolder.java

@@ -0,0 +1,26 @@
+package org.cryptomator.filesystem.blockaligned;
+
+import org.cryptomator.filesystem.File;
+import org.cryptomator.filesystem.Folder;
+import org.cryptomator.filesystem.delegating.DelegatingFolder;
+
+class BlockAlignedFolder extends DelegatingFolder<BlockAlignedReadableFile, BlockAlignedWritableFile, BlockAlignedFolder, BlockAlignedFile> {
+
+	private final int blockSize;
+
+	public BlockAlignedFolder(BlockAlignedFolder parent, Folder delegate, int blockSize) {
+		super(parent, delegate);
+		this.blockSize = blockSize;
+	}
+
+	@Override
+	protected BlockAlignedFile file(File delegate) {
+		return new BlockAlignedFile(this, delegate, blockSize);
+	}
+
+	@Override
+	protected BlockAlignedFolder folder(Folder delegate) {
+		return new BlockAlignedFolder(this, delegate, blockSize);
+	}
+
+}

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/BlockAlignedReadableFile.java

@@ -0,0 +1,27 @@
+package org.cryptomator.filesystem.blockaligned;
+
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+
+import org.cryptomator.filesystem.ReadableFile;
+import org.cryptomator.filesystem.delegating.DelegatingReadableFile;
+
+class BlockAlignedReadableFile extends DelegatingReadableFile {
+
+	public BlockAlignedReadableFile(ReadableFile delegate, int blockSize) {
+		super(delegate);
+	}
+
+	@Override
+	public void position(long position) throws UncheckedIOException {
+		// TODO Auto-generated method stub
+		super.position(position);
+	}
+
+	@Override
+	public int read(ByteBuffer target) throws UncheckedIOException {
+		// TODO Auto-generated method stub
+		return super.read(target);
+	}
+
+}

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/BlockAlignedWritableFile.java

@@ -0,0 +1,27 @@
+package org.cryptomator.filesystem.blockaligned;
+
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+
+import org.cryptomator.filesystem.WritableFile;
+import org.cryptomator.filesystem.delegating.DelegatingWritableFile;
+
+class BlockAlignedWritableFile extends DelegatingWritableFile {
+
+	public BlockAlignedWritableFile(WritableFile delegate, int blockSize) {
+		super(delegate);
+	}
+
+	@Override
+	public void position(long position) throws UncheckedIOException {
+		// TODO Auto-generated method stub
+		super.position(position);
+	}
+
+	@Override
+	public int write(ByteBuffer source) throws UncheckedIOException {
+		// TODO Auto-generated method stub
+		return super.write(source);
+	}
+
+}

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/blockaligned/package-info.java

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+/*******************************************************************************
+ * Copyright (c) 2015 Sebastian Stenzel and others.
+ * This file is licensed under the terms of the MIT license.
+ * See the LICENSE.txt file for more info.
+ *
+ * Contributors:
+ *     Sebastian Stenzel - initial API and implementation
+ *******************************************************************************/
+/**
+ * Provides a decoration layer for the {@link org.cryptomator.filesystem Filesystem API}, which guarantees, that all read/write attempts to underlying files always begin at a block start position.
+ * Block start positions are integer multiples of a block size + a fixed block shift.
+ * <p>
+ * In general the formula to align a requested read with a physical read is <code>floor(x / blockSize) * blockSize</code><br/>
+ * For example <code>blockSize=10</code> result in the following block-aligned read/write attempts:
+ * 
+ * <table>
+ * <thead>
+ * 	<tr><th>Requested Read</th><th>Physical Read</th></tr>
+ * </thead>
+ * <tbody>
+ * 	<tr><td>0</td><td>0</td></td>
+ * 	<tr><td>5</td><td>0</td></td>
+ * 	<tr><td>9</td><td>0</td></td>
+ * 	<tr><td>10</td><td>10</td></td>
+ * 	<tr><td>11</td><td>10</td></td>
+ * 	<tr><td>35</td><td>30</td></td>
+ * </tbody>
+ * </table>
+ */
+package org.cryptomator.filesystem.blockaligned;