Fixed reuse of directory-IDs after moving encrypted directories but keeping references to the old locations.

This caused an illegal state where two different directories share the same directory id, making further file operations on these directories virtually impossible.

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

@@ -10,10 +10,9 @@ package org.cryptomator.filesystem.crypto;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import java.util.Optional;
 import java.io.UncheckedIOException;
 import java.nio.file.FileAlreadyExistsException;
-import java.time.Instant;
+import java.util.Optional;
 
 import org.cryptomator.crypto.engine.Cryptor;
 import org.cryptomator.filesystem.File;

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

@@ -11,12 +11,10 @@ package org.cryptomator.filesystem.crypto;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.io.Reader;
 import java.io.UncheckedIOException;
-import java.io.Writer;
-import java.nio.channels.Channels;
 import java.nio.file.FileAlreadyExistsException;
+import java.util.Collection;
+import java.util.HashSet;
 import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicReference;
@@ -29,6 +27,7 @@ import org.cryptomator.common.WeakValuedCache;
 import org.cryptomator.crypto.engine.Cryptor;
 import org.cryptomator.filesystem.Deleter;
 import org.cryptomator.filesystem.File;
+import org.cryptomator.filesystem.FileSystemVisitor;
 import org.cryptomator.filesystem.Folder;
 import org.cryptomator.filesystem.Node;
 import org.cryptomator.io.FileContents;
@@ -164,11 +163,15 @@ class CryptoFolder extends CryptoNode implements Folder {
 		}
 		assert target.parent().isPresent() : "Target can not be root, thus has a parent";
 
+		// prepare target:
 		target.parent().get().create();
-
-		// explicitly delete target, otherwise same-named folders may keep their directory ids
 		target.delete();
 
+		// determine subFolder as long as we can still browse our current hierarchy:
+		Collection<Folder> subFolders = new HashSet<>();
+		FileSystemVisitor.fileSystemVisitor().beforeFolder(subFolders::add).visit(this);
+
+		// perform the actual move:
 		final File dirFile = forceGetPhysicalFile();
 		final String dirId = getDirectoryId().get();
 		boolean dirIdMovedSuccessfully = target.directoryId.compareAndSet(null, dirId);
@@ -176,17 +179,20 @@ class CryptoFolder extends CryptoNode implements Folder {
 			throw new IllegalStateException("Target's directoryId wasn't null, even though it has been explicitly deleted.");
 		}
 		dirFile.moveTo(target.forceGetPhysicalFile());
-		directoryId.set(null);
+
+		// invalidate the directory id of any directory beneath the _old_ location:
+		subFolders.stream().filter(CryptoFolder.class::isInstance).map(CryptoFolder.class::cast).forEach(folder -> {
+			folder.directoryId.set(null);
+		});
 
 		assert!exists();
 		assert target.exists();
-		assert!dirFile.exists();
 	}
 
 	@Override
 	public void delete() {
 		if (!exists()) {
-			directoryId.set(null);
+			assert directoryId.get() == null : "nonexisting folder still has a directory id";
 			return;
 		}
 		Deleter.deleteContent(this);

main/filesystem-inmemory/src/main/java/org/cryptomator/filesystem/inmem/InMemoryFile.java

@@ -69,6 +69,7 @@ class InMemoryFile extends InMemoryNode implements File {
 					throw new UncheckedIOException(new FileAlreadyExistsException(k));
 				} else {
 					if (v == null) {
+						assert!content.hasRemaining();
 						this.creationTime = Instant.now();
 					}
 					this.lastModified = Instant.now();