diff --git a/apps/files_external/lib/sftp.php b/apps/files_external/lib/sftp.php
index 572829f0fd..c37663c4f8 100644
--- a/apps/files_external/lib/sftp.php
+++ b/apps/files_external/lib/sftp.php
@@ -43,8 +43,9 @@ class SFTP extends \OC\Files\Storage\Common {
 	*/
 	protected $client;
 
-	private static $tempFiles = array();
-
+	/**
+	 * {@inheritdoc}
+	 */
 	public function __construct($params) {
 		// Register sftp://
 		\Net_SFTP_Stream::register();
@@ -100,6 +101,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		return $this->client;
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function test() {
 		if (
 			!isset($this->host)
@@ -111,29 +115,45 @@ class SFTP extends \OC\Files\Storage\Common {
 		return $this->getConnection()->nlist() !== false;
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function getId(){
 		return 'sftp::' . $this->user . '@' . $this->host . '/' . $this->root;
 	}
 
+	/**
+	 * @return string
+	 */
 	public function getHost() {
 		return $this->host;
 	}
 
+	/**
+	 * @return string
+	 */
 	public function getRoot() {
 		return $this->root;
 	}
 
+	/**
+	 * @return mixed
+	 */
 	public function getUser() {
 		return $this->user;
 	}
 
 	/**
 	 * @param string $path
+	 * @return string
 	 */
 	private function absPath($path) {
 		return $this->root . $this->cleanPath($path);
 	}
 
+	/**
+	 * @return bool|string
+	 */
 	private function hostKeysPath() {
 		try {
 			$storage_view = \OCP\Files::getStorage('files_external');
@@ -147,6 +167,10 @@ class SFTP extends \OC\Files\Storage\Common {
 		return false;
 	}
 
+	/**
+	 * @param $keys
+	 * @return bool
+	 */
 	protected function writeHostKeys($keys) {
 		try {
 			$keyPath = $this->hostKeysPath();
@@ -163,6 +187,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		return false;
 	}
 
+	/**
+	 * @return array
+	 */
 	protected function readHostKeys() {
 		try {
 			$keyPath = $this->hostKeysPath();
@@ -186,6 +213,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		return array();
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function mkdir($path) {
 		try {
 			return $this->getConnection()->mkdir($this->absPath($path));
@@ -194,6 +224,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function rmdir($path) {
 		try {
 			return $this->getConnection()->delete($this->absPath($path), true);
@@ -202,6 +235,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function opendir($path) {
 		try {
 			$list = $this->getConnection()->nlist($this->absPath($path));
@@ -223,6 +259,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function filetype($path) {
 		try {
 			$stat = $this->getConnection()->stat($this->absPath($path));
@@ -239,6 +278,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		return false;
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function file_exists($path) {
 		try {
 			return $this->getConnection()->stat($this->absPath($path)) !== false;
@@ -247,6 +289,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function unlink($path) {
 		try {
 			return $this->getConnection()->delete($this->absPath($path), true);
@@ -255,6 +300,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function fopen($path, $mode) {
 		try {
 			$absPath = $this->absPath($path);
@@ -284,6 +332,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		return false;
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function touch($path, $mtime=null) {
 		try {
 			if (!is_null($mtime)) {
@@ -300,14 +351,27 @@ class SFTP extends \OC\Files\Storage\Common {
 		return true;
 	}
 
+	/**
+	 * @param string $path
+	 * @param string $target
+	 * @throws \Exception
+	 */
 	public function getFile($path, $target) {
 		$this->getConnection()->get($path, $target);
 	}
 
+	/**
+	 * @param string $path
+	 * @param string $target
+	 * @throws \Exception
+	 */
 	public function uploadFile($path, $target) {
 		$this->getConnection()->put($target, $path, NET_SFTP_LOCAL_FILE);
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function rename($source, $target) {
 		try {
 			if (!$this->is_dir($target) && $this->file_exists($target)) {
@@ -322,6 +386,9 @@ class SFTP extends \OC\Files\Storage\Common {
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function stat($path) {
 		try {
 			$stat = $this->getConnection()->stat($this->absPath($path));
@@ -337,6 +404,7 @@ class SFTP extends \OC\Files\Storage\Common {
 
 	/**
 	 * @param string $path
+	 * @return string
 	 */
 	public function constructUrl($path) {
 		// Do not pass the password here. We want to use the Net_SFTP object