diff --git a/apps/files/ajax/upload.php b/apps/files/ajax/upload.php
index 0e905f993a..bdaf6a77d1 100644
--- a/apps/files/ajax/upload.php
+++ b/apps/files/ajax/upload.php
@@ -34,6 +34,7 @@ if (empty($_POST['dirToken'])) {
 		// resolve reshares
 		$rootLinkItem = OCP\Share::resolveReShare($linkItem);
 
+		OCP\JSON::checkUserExists($rootLinkItem['uid_owner']);
 		// Setup FS with owner
 		OC_Util::tearDownFS();
 		OC_Util::setupFS($rootLinkItem['uid_owner']);
diff --git a/apps/files/triggerupdate.php b/apps/files/triggerupdate.php
index 0e29edbba3..a37b9823ad 100644
--- a/apps/files/triggerupdate.php
+++ b/apps/files/triggerupdate.php
@@ -6,6 +6,7 @@ if (OC::$CLI) {
 	if (count($argv) === 2) {
 		$file = $argv[1];
 		list(, $user) = explode('/', $file);
+		OCP\JSON::checkUserExists($owner);
 		OC_Util::setupFS($user);
 		$view = new \OC\Files\View('');
 		/**
diff --git a/apps/files_encryption/tests/crypt.php b/apps/files_encryption/tests/crypt.php
index ca14e3e2cc..388980ad4f 100755
--- a/apps/files_encryption/tests/crypt.php
+++ b/apps/files_encryption/tests/crypt.php
@@ -155,7 +155,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testSymmetricStreamEncryptShortFileContent() {
 
-		$filename = 'tmp-' . time() . '.test';
+		$filename = 'tmp-' . uniqid() . '.test';
 
 		$util = new Encryption\Util(new \OC_FilesystemView(), $this->userId);
 
@@ -214,7 +214,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	function testSymmetricStreamEncryptLongFileContent() {
 
 		// Generate a a random filename
-		$filename = 'tmp-' . time() . '.test';
+		$filename = 'tmp-' . uniqid() . '.test';
 
 		$util = new Encryption\Util(new \OC_FilesystemView(), $this->userId);
 
@@ -297,7 +297,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testSymmetricStreamDecryptShortFileContent() {
 
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 
 		// Save long data as encrypted file using stream wrapper
 		$cryptedFile = file_put_contents('crypt:///'. $this->userId . '/files/' . $filename, $this->dataShort);
@@ -327,7 +327,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testSymmetricStreamDecryptLongFileContent() {
 
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 
 		// Save long data as encrypted file using stream wrapper
 		$cryptedFile = file_put_contents('crypt:///' . $this->userId . '/files/' . $filename, $this->dataLong);
@@ -418,7 +418,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testRenameFile() {
 
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 
 		// Save long data as encrypted file using stream wrapper
 		$cryptedFile = file_put_contents('crypt:///' . $this->userId . '/files/' . $filename, $this->dataLong);
@@ -431,7 +431,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 
 		$this->assertEquals($this->dataLong, $decrypt);
 
-		$newFilename = 'tmp-new-' . time();
+		$newFilename = 'tmp-new-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 		$view->rename($filename, $newFilename);
 
@@ -449,7 +449,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testMoveFileIntoFolder() {
 
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 
 		// Save long data as encrypted file using stream wrapper
 		$cryptedFile = file_put_contents('crypt:///' . $this->userId . '/files/' . $filename, $this->dataLong);
@@ -462,8 +462,8 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 
 		$this->assertEquals($this->dataLong, $decrypt);
 
-		$newFolder = '/newfolder' . time();
-		$newFilename = 'tmp-new-' . time();
+		$newFolder = '/newfolder' . uniqid();
+		$newFilename = 'tmp-new-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 		$view->mkdir($newFolder);
 		$view->rename($filename, $newFolder . '/' . $newFilename);
@@ -484,8 +484,8 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
-		$filename = '/tmp-' . time();
-		$folder = '/folder' . time();
+		$filename = '/tmp-' . uniqid();
+		$folder = '/folder' . uniqid();
 
 		$view->mkdir($folder);
 
@@ -500,7 +500,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 
 		$this->assertEquals($this->dataLong, $decrypt);
 
-		$newFolder = '/newfolder/subfolder' . time();
+		$newFolder = '/newfolder/subfolder' . uniqid();
 		$view->mkdir('/newfolder');
 
 		$view->rename($folder, $newFolder);
@@ -519,7 +519,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 * @medium
 	 */
 	function testChangePassphrase() {
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 
 		// Save long data as encrypted file using stream wrapper
 		$cryptedFile = file_put_contents('crypt:///' . $this->userId . '/files/' . $filename, $this->dataLong);
@@ -557,7 +557,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 */
 	function testViewFilePutAndGetContents() {
 
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -590,7 +590,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 * @large
 	 */
 	function testTouchExistingFile() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -614,7 +614,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 * @medium
 	 */
 	function testTouchFile() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		$view->touch($filename);
@@ -638,7 +638,7 @@ class Test_Encryption_Crypt extends \PHPUnit_Framework_TestCase {
 	 * @medium
 	 */
 	function testFopenFile() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
diff --git a/apps/files_encryption/tests/keymanager.php b/apps/files_encryption/tests/keymanager.php
index 1467979f00..58a57ee5af 100644
--- a/apps/files_encryption/tests/keymanager.php
+++ b/apps/files_encryption/tests/keymanager.php
@@ -143,7 +143,7 @@ class Test_Encryption_Keymanager extends \PHPUnit_Framework_TestCase {
 
 		$key = $this->randomKey;
 
-		$file = 'unittest-' . time() . '.txt';
+		$file = 'unittest-' . uniqid() . '.txt';
 
 		$util = new Encryption\Util($this->view, $this->userId);
 
@@ -196,7 +196,7 @@ class Test_Encryption_Keymanager extends \PHPUnit_Framework_TestCase {
 	function testRecursiveDelShareKeys() {
 
 		// generate filename
-		$filename = '/tmp-' . time() . '.txt';
+		$filename = '/tmp-' . uniqid() . '.txt';
 
 		// create folder structure
 		$this->view->mkdir('/'.Test_Encryption_Keymanager::TEST_USER.'/files/folder1');
diff --git a/apps/files_encryption/tests/proxy.php b/apps/files_encryption/tests/proxy.php
index 419f95e1a3..c3006274d6 100644
--- a/apps/files_encryption/tests/proxy.php
+++ b/apps/files_encryption/tests/proxy.php
@@ -80,7 +80,7 @@ class Test_Encryption_Proxy extends \PHPUnit_Framework_TestCase {
 
 		// init short data
 		$this->data = 'hats';
-		$this->filename = 'enc_proxy_tests-' . time() . '.txt';
+		$this->filename = 'enc_proxy_tests-' . uniqid() . '.txt';
 
 	}
 
diff --git a/apps/files_encryption/tests/stream.php b/apps/files_encryption/tests/stream.php
index 2767bbe512..fed2e7d89d 100644
--- a/apps/files_encryption/tests/stream.php
+++ b/apps/files_encryption/tests/stream.php
@@ -99,7 +99,7 @@ class Test_Encryption_Stream extends \PHPUnit_Framework_TestCase {
 	}
 
 	function testStreamOptions() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -122,7 +122,7 @@ class Test_Encryption_Stream extends \PHPUnit_Framework_TestCase {
 	}
 
 	function testStreamSetBlocking() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -144,7 +144,7 @@ class Test_Encryption_Stream extends \PHPUnit_Framework_TestCase {
 	 * @medium
 	 */
 	function testStreamSetTimeout() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -163,7 +163,7 @@ class Test_Encryption_Stream extends \PHPUnit_Framework_TestCase {
 	}
 
 	function testStreamSetWriteBuffer() {
-		$filename = '/tmp-' . time();
+		$filename = '/tmp-' . uniqid();
 		$view = new \OC\Files\View('/' . $this->userId . '/files');
 
 		// Save short data as encrypted file using stream wrapper
@@ -187,9 +187,9 @@ class Test_Encryption_Stream extends \PHPUnit_Framework_TestCase {
 	 */
 	function testStreamFromLocalFile() {
 
-		$filename = '/' . $this->userId . '/files/' . 'tmp-' . time().'.txt';
+		$filename = '/' . $this->userId . '/files/' . 'tmp-' . uniqid().'.txt';
 
-		$tmpFilename = "/tmp/" . time() . ".txt";
+		$tmpFilename = "/tmp/" . uniqid() . ".txt";
 
 		// write an encrypted file
 		$cryptedFile = $this->view->file_put_contents($filename, $this->dataShort);
diff --git a/apps/files_encryption/tests/trashbin.php b/apps/files_encryption/tests/trashbin.php
index 2a41ace401..2f9ecfd9d5 100755
--- a/apps/files_encryption/tests/trashbin.php
+++ b/apps/files_encryption/tests/trashbin.php
@@ -119,7 +119,7 @@ class Test_Encryption_Trashbin extends \PHPUnit_Framework_TestCase {
 	function testDeleteFile() {
 
 		// generate filename
-		$filename = 'tmp-' . time() . '.txt';
+		$filename = 'tmp-' . uniqid() . '.txt';
 
 		// save file with content
 		$cryptedFile = file_put_contents('crypt:///' .\Test_Encryption_Trashbin::TEST_ENCRYPTION_TRASHBIN_USER1. '/files/'. $filename, $this->dataShort);
@@ -223,7 +223,7 @@ class Test_Encryption_Trashbin extends \PHPUnit_Framework_TestCase {
 	function testPermanentDeleteFile() {
 
 		// generate filename
-		$filename = 'tmp-' . time() . '.txt';
+		$filename = 'tmp-' . uniqid() . '.txt';
 
 		// save file with content
 		$cryptedFile = file_put_contents('crypt:///' .$this->userId. '/files/' . $filename, $this->dataShort);
diff --git a/apps/files_encryption/tests/util.php b/apps/files_encryption/tests/util.php
index b1904cbadc..97e3c518da 100755
--- a/apps/files_encryption/tests/util.php
+++ b/apps/files_encryption/tests/util.php
@@ -142,8 +142,8 @@ class Test_Encryption_Util extends \PHPUnit_Framework_TestCase {
 
 		self::loginHelper($this->userId);
 
-		$unencryptedFile = '/tmpUnencrypted-' . time() . '.txt';
-		$encryptedFile =  '/tmpEncrypted-' . time() . '.txt';
+		$unencryptedFile = '/tmpUnencrypted-' . uniqid() . '.txt';
+		$encryptedFile =  '/tmpEncrypted-' . uniqid() . '.txt';
 
 		// Disable encryption proxy to write a unencrypted file
 		$proxyStatus = \OC_FileProxy::$enabled;
@@ -254,7 +254,7 @@ class Test_Encryption_Util extends \PHPUnit_Framework_TestCase {
 
 		\OC_User::setUserId(\Test_Encryption_Util::TEST_ENCRYPTION_UTIL_USER1);
 
-		$filename = '/tmp-' . time() . '.test';
+		$filename = '/tmp-' . uniqid() . '.test';
 
 		// Disable encryption proxy to prevent recursive calls
 		$proxyStatus = \OC_FileProxy::$enabled;
@@ -282,7 +282,7 @@ class Test_Encryption_Util extends \PHPUnit_Framework_TestCase {
 	function testGetFileSize() {
 		\Test_Encryption_Util::loginHelper(\Test_Encryption_Util::TEST_ENCRYPTION_UTIL_USER1);
 
-		$filename = 'tmp-' . time();
+		$filename = 'tmp-' . uniqid();
 		$externalFilename = '/' . $this->userId . '/files/' . $filename;
 
 		// Test for 0 byte files
@@ -318,7 +318,7 @@ class Test_Encryption_Util extends \PHPUnit_Framework_TestCase {
 
 	function testEncryptAll() {
 
-		$filename = "/encryptAll" . time() . ".txt";
+		$filename = "/encryptAll" . uniqid() . ".txt";
 		$util = new Encryption\Util($this->view, $this->userId);
 
 		// disable encryption to upload a unencrypted file
@@ -350,7 +350,7 @@ class Test_Encryption_Util extends \PHPUnit_Framework_TestCase {
 
 	function testDecryptAll() {
 
-		$filename = "/decryptAll" . time() . ".txt";
+		$filename = "/decryptAll" . uniqid() . ".txt";
 		$util = new Encryption\Util($this->view, $this->userId);
 
 		$this->view->file_put_contents($this->userId . '/files/' . $filename, $this->dataShort);
diff --git a/apps/files_encryption/tests/webdav.php b/apps/files_encryption/tests/webdav.php
index a2a8ce6e34..8e8b9c53ce 100755
--- a/apps/files_encryption/tests/webdav.php
+++ b/apps/files_encryption/tests/webdav.php
@@ -113,7 +113,7 @@ class Test_Encryption_Webdav extends \PHPUnit_Framework_TestCase {
 	function testWebdavPUT() {
 
 		// generate filename
-		$filename = '/tmp-' . time() . '.txt';
+		$filename = '/tmp-' . uniqid() . '.txt';
 
 		// set server vars
 		$_SERVER['REQUEST_METHOD'] = 'OPTIONS';
diff --git a/apps/files_sharing/ajax/publicpreview.php b/apps/files_sharing/ajax/publicpreview.php
index 54a9806e8b..a52f522afa 100644
--- a/apps/files_sharing/ajax/publicpreview.php
+++ b/apps/files_sharing/ajax/publicpreview.php
@@ -39,6 +39,7 @@ if(!isset($linkedItem['uid_owner']) || !isset($linkedItem['file_source'])) {
 $rootLinkItem = OCP\Share::resolveReShare($linkedItem);
 $userId = $rootLinkItem['uid_owner'];
 
+OCP\JSON::checkUserExists($rootLinkItem['uid_owner']);
 \OC_Util::setupFS($userId);
 \OC\Files\Filesystem::initMountPoints($userId);
 $view = new \OC\Files\View('/' . $userId . '/files');
@@ -88,4 +89,4 @@ try{
 } catch (\Exception $e) {
 	\OC_Response::setStatus(500);
 	\OC_Log::write('core', $e->getmessage(), \OC_Log::DEBUG);
-}
\ No newline at end of file
+}
diff --git a/apps/files_sharing/appinfo/update.php b/apps/files_sharing/appinfo/update.php
index 0d827da28e..4b716e764f 100644
--- a/apps/files_sharing/appinfo/update.php
+++ b/apps/files_sharing/appinfo/update.php
@@ -44,6 +44,7 @@ if (version_compare($installedVersion, '0.3', '<')) {
 				$shareType = OCP\Share::SHARE_TYPE_USER;
 				$shareWith = $row['uid_shared_with'];
 			}
+			OCP\JSON::checkUserExists($row['uid_owner']);
 			OC_User::setUserId($row['uid_owner']);
 			//we need to setup the filesystem for the user, otherwise OC_FileSystem::getRoot will fail and break
 			OC_Util::setupFS($row['uid_owner']);
diff --git a/apps/files_sharing/public.php b/apps/files_sharing/public.php
index 100379047d..4a81e48297 100644
--- a/apps/files_sharing/public.php
+++ b/apps/files_sharing/public.php
@@ -43,10 +43,10 @@ if (isset($_GET['t'])) {
 		$shareOwner = $linkItem['uid_owner'];
 		$path = null;
 		$rootLinkItem = OCP\Share::resolveReShare($linkItem);
-		$fileOwner = $rootLinkItem['uid_owner'];
-		if (isset($fileOwner)) {
+		if (isset($rootLinkItem['uid_owner'])) {
+			OCP\JSON::checkUserExists($rootLinkItem['uid_owner']);
 			OC_Util::tearDownFS();
-			OC_Util::setupFS($fileOwner);
+			OC_Util::setupFS($rootLinkItem['uid_owner']);
 			$path = \OC\Files\Filesystem::getPath($linkItem['file_source']);
 		}
 	}
diff --git a/apps/files_versions/lib/versions.php b/apps/files_versions/lib/versions.php
index 01c2e1ccde..8463bd9482 100644
--- a/apps/files_versions/lib/versions.php
+++ b/apps/files_versions/lib/versions.php
@@ -417,6 +417,65 @@ class Storage {
 		return $result;
 	}
 
+	/**
+	 * @brief get list of files we want to expire
+	 * @param int $currentTime timestamp of current time
+	 * @param array $versions list of versions
+	 * @return array containing the list of to deleted versions and the size of them
+	 */
+	protected static function getExpireList($time, $versions) {
+
+		$size = 0;
+		$toDelete = array();  // versions we want to delete
+
+		$versions = array_reverse($versions); // newest version first
+
+		$interval = 1;
+		$step = Storage::$max_versions_per_interval[$interval]['step'];
+		if (Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'] == -1) {
+			$nextInterval = -1;
+		} else {
+			$nextInterval = $time - Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'];
+		}
+
+		$firstVersion = reset($versions);
+		$firstKey = key($versions);
+		$prevTimestamp = $firstVersion['version'];
+		$nextVersion = $firstVersion['version'] - $step;
+		unset($versions[$firstKey]);
+
+		foreach ($versions as $key => $version) {
+			$newInterval = true;
+			while ($newInterval) {
+				if ($nextInterval == -1 || $prevTimestamp > $nextInterval) {
+					if ($version['version'] > $nextVersion) {
+						//distance between two version too small, mark to delete
+						$toDelete[$key] = $version['path'] . '.v' . $version['version'];
+						$size += $version['size'];
+						\OCP\Util::writeLog('files_versions', 'Mark to expire '. $version['path'] .' next version should be ' . $nextVersion . " or smaller. (prevTimestamp: " . $prevTimestamp . "; step: " . $step, \OCP\Util::DEBUG);
+					} else {
+						$nextVersion = $version['version'] - $step;
+						$prevTimestamp = $version['version'];
+					}
+					$newInterval = false; // version checked so we can move to the next one
+				} else { // time to move on to the next interval
+					$interval++;
+					$step = Storage::$max_versions_per_interval[$interval]['step'];
+					$nextVersion = $prevTimestamp - $step;
+					if (Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'] == -1) {
+						$nextInterval = -1;
+					} else {
+						$nextInterval = $time - Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'];
+					}
+					$newInterval = true; // we changed the interval -> check same version with new interval
+				}
+			}
+		}
+
+		return array($toDelete, $size);
+
+	}
+
 	/**
 	 * @brief Erase a file's versions which exceed the set quota
 	 */
@@ -461,33 +520,35 @@ class Storage {
 				$availableSpace = $quota - $offset;
 			}
 
-
-			// with the  probability of 0.1% we reduce the number of all versions not only for the current file
-			$random = rand(0, 1000);
-			if ($random == 0) {
-				$allFiles = true;
-			} else {
-				$allFiles = false;
-			}
-
 			$allVersions = Storage::getVersions($uid, $filename);
-			$versionsByFile[$filename] = $allVersions;
 
-			$sizeOfDeletedVersions = self::delOldVersions($versionsByFile, $allVersions, $versionsFileview);
+			$time = time();
+			list($toDelete, $sizeOfDeletedVersions) = self::getExpireList($time, $allVersions);
+
 			$availableSpace = $availableSpace + $sizeOfDeletedVersions;
 			$versionsSize = $versionsSize - $sizeOfDeletedVersions;
 
 			// if still not enough free space we rearrange the versions from all files
-			if ($availableSpace <= 0 || $allFiles) {
+			if ($availableSpace <= 0) {
 				$result = Storage::getAllVersions($uid);
-				$versionsByFile = $result['by_file'];
 				$allVersions = $result['all'];
 
-				$sizeOfDeletedVersions = self::delOldVersions($versionsByFile, $allVersions, $versionsFileview);
+				foreach ($result['by_file'] as $versions) {
+					list($toDeleteNew, $size) = self::getExpireList($time, $versions);
+					$toDelete = array_merge($toDelete, $toDeleteNew);
+					$sizeOfDeletedVersions += $size;
+				}
 				$availableSpace = $availableSpace + $sizeOfDeletedVersions;
 				$versionsSize = $versionsSize - $sizeOfDeletedVersions;
 			}
 
+			foreach($toDelete as $key => $path) {
+				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $path));
+				$versionsFileview->unlink($path);
+				unset($allVersions[$key]); // update array with the versions we keep
+				\OCP\Util::writeLog('files_versions', "Expire: " . $path, \OCP\Util::DEBUG);
+			}
+
 			// Check if enough space is available after versions are rearranged.
 			// If not we delete the oldest versions until we meet the size limit for versions,
 			// but always keep the two latest versions
@@ -497,6 +558,7 @@ class Storage {
 				$version = current($allVersions);
 				$versionsFileview->unlink($version['path'].'.v'.$version['version']);
 				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'].'.v'.$version['version']));
+				\OCP\Util::writeLog('files_versions', 'running out of space! Delete oldest version: ' . $version['path'].'.v'.$version['version'] , \OCP\Util::DEBUG);
 				$versionsSize -= $version['size'];
 				$availableSpace += $version['size'];
 				next($allVersions);
@@ -509,69 +571,6 @@ class Storage {
 		return false;
 	}
 
-	/**
-	 * @brief delete old version from a given list of versions
-	 *
-	 * @param array $versionsByFile list of versions ordered by files
-	 * @param array $allVversions all versions across multiple files
-	 * @param $versionsFileview \OC\Files\View on data/user/files_versions
-	 * @return size of releted versions
-	 */
-	private static function delOldVersions($versionsByFile, &$allVersions, $versionsFileview) {
-
-		$time = time();
-		$size = 0;
-
-		// delete old versions for every given file
-		foreach ($versionsByFile as $versions) {
-			$versions = array_reverse($versions); // newest version first
-
-			$interval = 1;
-			$step = Storage::$max_versions_per_interval[$interval]['step'];
-			if (Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'] == -1) {
-				$nextInterval = -1;
-			} else {
-				$nextInterval = $time - Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'];
-			}
-
-			$firstVersion = reset($versions);
-			$firstKey = key($versions);
-			$prevTimestamp = $firstVersion['version'];
-			$nextVersion = $firstVersion['version'] - $step;
-			unset($versions[$firstKey]);
-
-			foreach ($versions as $key => $version) {
-				$newInterval = true;
-				while ($newInterval) {
-					if ($nextInterval == -1 || $version['version'] >= $nextInterval) {
-						if ($version['version'] > $nextVersion) {
-							//distance between two version too small, delete version
-							$versionsFileview->unlink($version['path'] . '.v' . $version['version']);
-							\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'] . '.v' . $version['version']));
-							$size += $version['size'];
-							unset($allVersions[$key]); // update array with all versions
-						} else {
-							$nextVersion = $version['version'] - $step;
-						}
-						$newInterval = false; // version checked so we can move to the next one
-					} else { // time to move on to the next interval
-						$interval++;
-						$step = Storage::$max_versions_per_interval[$interval]['step'];
-						$nextVersion = $prevTimestamp - $step;
-						if (Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'] == -1) {
-							$nextInterval = -1;
-						} else {
-							$nextInterval = $time - Storage::$max_versions_per_interval[$interval]['intervalEndsAfter'];
-						}
-						$newInterval = true; // we changed the interval -> check same version with new interval
-					}
-				}
-				$prevTimestamp = $version['version'];
-			}
-		}
-		return $size;
-	}
-
 	/**
 	 * @brief create recursively missing directories
 	 * @param string $filename $path to a file
diff --git a/apps/files_versions/tests/versions.php b/apps/files_versions/tests/versions.php
new file mode 100644
index 0000000000..713f7796c9
--- /dev/null
+++ b/apps/files_versions/tests/versions.php
@@ -0,0 +1,188 @@
+<?php
+/**
+ * ownCloud
+ *
+ * @author Bjoern Schiessle
+ * @copyright 2014 Bjoern Schiessle <schiessle@owncloud.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+require_once __DIR__ . '/../lib/versions.php';
+
+/**
+ * Class Test_Files_versions
+ * @brief this class provide basic files versions test
+ */
+class Test_Files_Versioning extends \PHPUnit_Framework_TestCase {
+
+
+	/**
+	 * @medium
+	 * @brief test expire logic
+	 * @dataProvider versionsProvider
+	 */
+	function testGetExpireList($versions, $sizeOfAllDeletedFiles) {
+
+		// last interval enda at 2592000
+		$startTime = 5000000;
+
+		$testClass = new VersionStorageToTest();
+		list($deleted, $size) = $testClass->callProtectedGetExpireList($startTime, array_reverse($versions));
+
+		// we should have deleted 16 files each of the size 1
+		$this->assertEquals($sizeOfAllDeletedFiles, $size);
+
+		// the deleted array should only contain versions which should be deleted
+		foreach($deleted as $key => $path) {
+			unset($versions[$key]);
+			$this->assertEquals("delete", substr($path, 0, strlen("delete")));
+		}
+
+		// the versions array should only contain versions which should be kept
+		foreach ($versions as $version) {
+			$this->assertEquals("keep", $version['path']);
+		}
+
+	}
+
+	public function versionsProvider() {
+		return array(
+			// first set of versions uniformly distributed versions
+			array(
+				array(
+					// first slice (10sec) keep one version every 2 seconds
+					array("version" => 4999999, "path" => "keep", "size" => 1),
+					array("version" => 4999998, "path" => "delete", "size" => 1),
+					array("version" => 4999997, "path" => "keep", "size" => 1),
+					array("version" => 4999995, "path" => "keep", "size" => 1),
+					array("version" => 4999994, "path" => "delete", "size" => 1),
+					//next slice (60sec) starts at 4999990 keep one version every 10 secons
+					array("version" => 4999988, "path" => "keep", "size" => 1),
+					array("version" => 4999978, "path" => "keep", "size" => 1),
+					array("version" => 4999975, "path" => "delete", "size" => 1),
+					array("version" => 4999972, "path" => "delete", "size" => 1),
+					array("version" => 4999967, "path" => "keep", "size" => 1),
+					array("version" => 4999958, "path" => "delete", "size" => 1),
+					array("version" => 4999957, "path" => "keep", "size" => 1),
+					//next slice (3600sec) start at 4999940 keep one version every 60 seconds
+					array("version" => 4999900, "path" => "keep", "size" => 1),
+					array("version" => 4999841, "path" => "delete", "size" => 1),
+					array("version" => 4999840, "path" => "keep", "size" => 1),
+					array("version" => 4999780, "path" => "keep", "size" => 1),
+					array("version" => 4996401, "path" => "keep", "size" => 1),
+					// next slice (86400sec) start at 4996400 keep one version every 3600 seconds
+					array("version" => 4996350, "path" => "delete", "size" => 1),
+					array("version" => 4992800, "path" => "keep", "size" => 1),
+					array("version" => 4989800, "path" => "delete", "size" => 1),
+					array("version" => 4989700, "path" => "delete", "size" => 1),
+					array("version" => 4989200, "path" => "keep", "size" => 1),
+					// next slice (2592000sec) start at 4913600 keep one version every 86400 seconds
+					array("version" => 4913600, "path" => "keep", "size" => 1),
+					array("version" => 4852800, "path" => "delete", "size" => 1),
+					array("version" => 4827201, "path" => "delete", "size" => 1),
+					array("version" => 4827200, "path" => "keep", "size" => 1),
+					array("version" => 4777201, "path" => "delete", "size" => 1),
+					array("version" => 4777501, "path" => "delete", "size" => 1),
+					array("version" => 4740000, "path" => "keep", "size" => 1),
+					// final slice starts at 2408000 keep one version every 604800 secons
+					array("version" => 2408000, "path" => "keep", "size" => 1),
+					array("version" => 1803201, "path" => "delete", "size" => 1),
+					array("version" => 1803200, "path" => "keep", "size" => 1),
+					array("version" => 1800199, "path" => "delete", "size" => 1),
+					array("version" => 1800100, "path" => "delete", "size" => 1),
+					array("version" => 1198300, "path" => "keep", "size" => 1),
+				),
+				16 // size of all deleted files (every file has the size 1)
+			),
+			// second set of versions, here we have only really old versions
+			array(
+				array(
+					// first slice (10sec) keep one version every 2 seconds
+					// next slice (60sec) starts at 4999990 keep one version every 10 secons
+					// next slice (3600sec) start at 4999940 keep one version every 60 seconds
+					// next slice (86400sec) start at 4996400 keep one version every 3600 seconds
+					array("version" => 4996400, "path" => "keep", "size" => 1),
+					array("version" => 4996350, "path" => "delete", "size" => 1),
+					array("version" => 4996350, "path" => "delete", "size" => 1),
+					array("version" => 4992800, "path" => "keep", "size" => 1),
+					array("version" => 4989800, "path" => "delete", "size" => 1),
+					array("version" => 4989700, "path" => "delete", "size" => 1),
+					array("version" => 4989200, "path" => "keep", "size" => 1),
+					// next slice (2592000sec) start at 4913600 keep one version every 86400 seconds
+					array("version" => 4913600, "path" => "keep", "size" => 1),
+					array("version" => 4852800, "path" => "delete", "size" => 1),
+					array("version" => 4827201, "path" => "delete", "size" => 1),
+					array("version" => 4827200, "path" => "keep", "size" => 1),
+					array("version" => 4777201, "path" => "delete", "size" => 1),
+					array("version" => 4777501, "path" => "delete", "size" => 1),
+					array("version" => 4740000, "path" => "keep", "size" => 1),
+					// final slice starts at 2408000 keep one version every 604800 secons
+					array("version" => 2408000, "path" => "keep", "size" => 1),
+					array("version" => 1803201, "path" => "delete", "size" => 1),
+					array("version" => 1803200, "path" => "keep", "size" => 1),
+					array("version" => 1800199, "path" => "delete", "size" => 1),
+					array("version" => 1800100, "path" => "delete", "size" => 1),
+					array("version" => 1198300, "path" => "keep", "size" => 1),
+				),
+				11 // size of all deleted files (every file has the size 1)
+			),
+			// third set of versions, with some gaps inbetween
+			array(
+				array(
+					// first slice (10sec) keep one version every 2 seconds
+					array("version" => 4999999, "path" => "keep", "size" => 1),
+					array("version" => 4999998, "path" => "delete", "size" => 1),
+					array("version" => 4999997, "path" => "keep", "size" => 1),
+					array("version" => 4999995, "path" => "keep", "size" => 1),
+					array("version" => 4999994, "path" => "delete", "size" => 1),
+					//next slice (60sec) starts at 4999990 keep one version every 10 secons
+					array("version" => 4999988, "path" => "keep", "size" => 1),
+					array("version" => 4999978, "path" => "keep", "size" => 1),
+					//next slice (3600sec) start at 4999940 keep one version every 60 seconds
+					// next slice (86400sec) start at 4996400 keep one version every 3600 seconds
+					array("version" => 4989200, "path" => "keep", "size" => 1),
+					// next slice (2592000sec) start at 4913600 keep one version every 86400 seconds
+					array("version" => 4913600, "path" => "keep", "size" => 1),
+					array("version" => 4852800, "path" => "delete", "size" => 1),
+					array("version" => 4827201, "path" => "delete", "size" => 1),
+					array("version" => 4827200, "path" => "keep", "size" => 1),
+					array("version" => 4777201, "path" => "delete", "size" => 1),
+					array("version" => 4777501, "path" => "delete", "size" => 1),
+					array("version" => 4740000, "path" => "keep", "size" => 1),
+					// final slice starts at 2408000 keep one version every 604800 secons
+					array("version" => 2408000, "path" => "keep", "size" => 1),
+					array("version" => 1803201, "path" => "delete", "size" => 1),
+					array("version" => 1803200, "path" => "keep", "size" => 1),
+					array("version" => 1800199, "path" => "delete", "size" => 1),
+					array("version" => 1800100, "path" => "delete", "size" => 1),
+					array("version" => 1198300, "path" => "keep", "size" => 1),
+				),
+				9 // size of all deleted files (every file has the size 1)
+			),
+
+		);
+	}
+
+}
+
+// extend the original class to make it possible to test protected methods
+class VersionStorageToTest extends \OCA\Files_Versions\Storage {
+
+	public function callProtectedGetExpireList($time, $versions) {
+		return self::getExpireList($time, $versions);
+
+	}
+}
diff --git a/lib/private/json.php b/lib/private/json.php
index 6a9e5a2df5..5c5d7e3a3d 100644
--- a/lib/private/json.php
+++ b/lib/private/json.php
@@ -64,6 +64,20 @@ class OC_JSON{
 		}
 	}
 
+	/**
+	 * Check is a given user exists - send json error msg if not
+	 * @param string $user
+	 */
+	public static function checkUserExists($user) {
+		if (!OCP\User::userExists($user)) {
+			$l = OC_L10N::get('lib');
+			OCP\JSON::error(array('data' => array('message' => $l->t('Unknown user'))));
+			exit;
+		}
+	}
+
+
+
 	/**
 	* Check if the user is a subadmin, send json error msg if not
 	*/
diff --git a/lib/private/template/cssresourcelocator.php b/lib/private/template/cssresourcelocator.php
index e26daa2582..8e7831ca54 100644
--- a/lib/private/template/cssresourcelocator.php
+++ b/lib/private/template/cssresourcelocator.php
@@ -22,7 +22,7 @@ class CSSResourceLocator extends ResourceLocator {
 		$app = substr($style, 0, strpos($style, '/'));
 		$style = substr($style, strpos($style, '/')+1);
 		$app_path = \OC_App::getAppPath($app);
-		$app_url = \OC_App::getAppWebPath($app);
+		$app_url = $this->webroot . '/index.php/apps/' . $app;
 		if ($this->appendIfExist($app_path, $style.$this->form_factor.'.css', $app_url)
 			|| $this->appendIfExist($app_path, $style.'.css', $app_url)
 		) {
diff --git a/lib/private/util.php b/lib/private/util.php
index 72afa6f947..8aa7a074d0 100755
--- a/lib/private/util.php
+++ b/lib/private/util.php
@@ -51,6 +51,10 @@ class OC_Util {
 			self::$rootMounted = true;
 		}
 
+		if ($user != '' && !OCP\User::userExists($user)) {
+			return false;
+		}
+
 		//if we aren't logged in, there is no use to set up the filesystem
 		if( $user != "" ) {
 			\OC\Files\Filesystem::addStorageWrapper(function($mountPoint, $storage){
diff --git a/lib/public/json.php b/lib/public/json.php
index 831e3ef1cf..cd5d233ef9 100644
--- a/lib/public/json.php
+++ b/lib/public/json.php
@@ -167,7 +167,7 @@ class JSON {
 	* @return string json formatted string if not admin user.
 	*/
 	public static function checkAdminUser() {
-		return(\OC_JSON::checkAdminUser());
+		\OC_JSON::checkAdminUser();
 	}
 
 	/**
@@ -177,4 +177,12 @@ class JSON {
 	public static function encode($data) {
 		return(\OC_JSON::encode($data));
 	}
+
+	/**
+	 * Check is a given user exists - send json error msg if not
+	 * @param string $user
+	 */
+	public static function checkUserExists($user) {
+		\OC_JSON::checkUserExists($user);
+	}
 }
diff --git a/tests/enable_all.php b/tests/enable_all.php
index d54418ff8e..efb43cae50 100644
--- a/tests/enable_all.php
+++ b/tests/enable_all.php
@@ -20,4 +20,5 @@ enableApp('files_sharing');
 enableApp('files_encryption');
 //enableApp('files_external');
 enableApp('user_ldap');
+enableApp('files_versions');