Added ReadableFile#size()

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/crypto/CryptoReadableFile.java

@@ -61,6 +61,12 @@ class CryptoReadableFile implements ReadableFile {
 		}
 	}
 
+	@Override
+	public long size() throws UncheckedIOException {
+		assert decryptor != null : "decryptor is always being set during position(long)";
+		return decryptor.contentLength();
+	}
+
 	@Override
 	public void position(long position) throws UncheckedIOException {
 		if (readAheadTask != null) {

main/filesystem-crypto/src/main/java/org/cryptomator/filesystem/crypto/CryptoWritableFile.java

@@ -109,6 +109,7 @@ class CryptoWritableFile implements WritableFile {
 			encryptor.append(FileContentCryptor.EOF);
 			writeTask.get();
 			writeHeader();
+			// TODO append padding
 		} catch (ExecutionException e) {
 			if (e.getCause() instanceof UncheckedIOException) {
 				throw (UncheckedIOException) e.getCause();