diff --git a/apps/files_external/lib/streamwrapper.php b/apps/files_external/lib/streamwrapper.php
index 44bd9a0161..d749f62afe 100644
--- a/apps/files_external/lib/streamwrapper.php
+++ b/apps/files_external/lib/streamwrapper.php
@@ -103,5 +103,4 @@ abstract class StreamWrapper extends Common {
 	public function stat($path) {
 		return stat($this->constructUrl($path));
 	}
-
 }
diff --git a/lib/private/files/storage/local.php b/lib/private/files/storage/local.php
index e33747bbd5..565f9202d5 100644
--- a/lib/private/files/storage/local.php
+++ b/lib/private/files/storage/local.php
@@ -279,5 +279,19 @@ if (\OC_Util::runningOnWindows()) {
 		public function isLocal() {
 			return true;
 		}
+
+		/**
+		 * Acquire a lock on a file
+		 */
+		public function getLock($path, $lockType) {
+			return true;
+		}
+
+		/**
+		 * Release an existing lock
+		 */
+		public function releaseLock($path) {
+			return true;
+		}
 	}
 }
diff --git a/lib/private/files/storage/wrapper/lockingwrapper.php b/lib/private/files/storage/wrapper/lockingwrapper.php
new file mode 100644
index 0000000000..04a325940b
--- /dev/null
+++ b/lib/private/files/storage/wrapper/lockingwrapper.php
@@ -0,0 +1,139 @@
+<?php
+
+/**
+ * Copyright (c) 2013 ownCloud, Inc.
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OC\Files\Storage\Wrapper;
+
+use OC\Files\Filesystem;
+use OCP\Files\LockNotAcquiredException;
+use OCP\Files\Lock;
+
+/**
+ * Class LockingWrapper
+ * A Storage Wrapper used to lock files at the system level
+ * @package OC\Files\Storage\Wrapper
+ *
+ * Notes: Does the $locks array need to be global to all LockingWrapper instances, such as in the case of two paths
+ * that point to the same physical file?  Otherwise accessing the file from a different path the second time would show
+ * the file as locked, even though this process is the one locking it.
+ */
+class LockingWrapper extends Wrapper {
+
+	/** @var array $locks Holds an array of lock instances indexed by path for this storage */
+	protected $locks = array();
+
+	/**
+	 * Acquire a lock on a file
+	 * @param string $path Path to file, relative to this storage
+	 * @param integer $lockType A Lock class constant, Lock::READ/Lock::WRITE
+	 * @return bool|\OCP\Files\Lock Lock instance on success, false on failure
+	 */
+	protected function getLock($path, $lockType){
+		$path = Filesystem::normalizePath($path);
+		if(!isset($this->locks[$path])) {
+			$this->locks[$path] = new Lock($path);
+		}
+		$this->locks[$path]->addLock($lockType);
+		return $this->locks[$path];
+	}
+
+	/**
+	 * Release an existing lock
+	 * @param string $path Path to file, relative to this storage
+	 * @return bool true on success, false on failure
+	 */
+	protected function releaseLock($path, $lockType, $releaseAll = false){
+		$path = Filesystem::normalizePath($path);
+		if(isset($this->locks[$path])) {
+			if($releaseAll) {
+				return $this->locks[$path]->releaseAll();
+			}
+			else {
+				return $this->locks[$path]->release($lockType);
+			}
+		}
+		return true;
+	}
+
+	/**
+	 * see http://php.net/manual/en/function.file_get_contents.php
+	 * @param string $path
+	 * @return string
+	 * @throws \Exception
+	 */
+	public function file_get_contents($path) {
+		try {
+			if (!$this->getLock($path, Lock::READ)) {
+				throw new LockNotAcquiredException($path, Lock::READ);
+			}
+			$result = $this->storage->file_get_contents($path);
+		}
+		catch(\Exception $originalException) {
+			// Need to release the lock before more operations happen in upstream exception handlers
+			$this->releaseLock($path, Lock::READ);
+			throw $originalException;
+		}
+		return $result;
+	}
+
+	public function file_put_contents($path, $data) {
+		try {
+			if (!$this->getLock($path, Lock::WRITE)) {
+				throw new LockNotAcquiredException($path, Lock::WRITE);
+			}
+			$result = $this->storage->file_put_contents($path, $data);
+		}
+		catch(\Exception $originalException) {
+			// Release lock, throw original exception
+			$this->releaseLock($path, Lock::WRITE);
+			throw $originalException;
+		}
+		return $result;
+	}
+
+
+	public function copy($path1, $path2) {
+		try {
+			if (!$this->getLock($path1, Lock::READ)) {
+				throw new LockNotAcquiredException($path1, Lock::READ);
+			}
+			if (!$this->getLock($path2, Lock::WRITE)) {
+				throw new LockNotAcquiredException($path2, Lock::WRITE);
+			}
+			$result = $this->storage->copy($path1, $path2);
+		}
+		catch(\Exception $originalException) {
+			// Release locks, throw original exception
+			$this->releaseLock($path1, Lock::READ);
+			$this->releaseLock($path2, Lock::WRITE);
+			throw $originalException;
+		}
+		return $result;
+	}
+
+	public function rename($path1, $path2) {
+		try {
+			if (!$this->getLock($path1, Lock::READ)) {
+				throw new LockNotAcquiredException($path1, Lock::READ);
+			}
+			if (!$this->getLock($path2, Lock::WRITE)) {
+				throw new LockNotAcquiredException($path2, Lock::WRITE);
+			}
+			$result = $this->storage->rename($path1, $path2);
+		}
+		catch(\Exception $originalException) {
+			// Release locks, throw original exception
+			$this->releaseLock($path1, Lock::READ);
+			$this->releaseLock($path2, Lock::WRITE);
+			throw $originalException;
+		}
+		return $result;
+	}
+
+
+}
\ No newline at end of file
diff --git a/lib/private/util.php b/lib/private/util.php
index 306e37b947..8cc48c0346 100755
--- a/lib/private/util.php
+++ b/lib/private/util.php
@@ -71,6 +71,16 @@ class OC_Util {
 				return $storage;
 			});
 
+			// Set up flock
+			\OC\Files\Filesystem::addStorageWrapper(function($mountPoint, /** @var \OC\Files\Storage\Storage|null $storage */ $storage){
+				// lock files on all local storage
+				if ($storage instanceof \OC\Files\Storage\Storage && $storage->isLocal()) {
+					return new \OC\Files\Storage\Wrapper\LockingWrapper(array('storage' => $storage));
+				} else {
+					return $storage;
+				}
+			});
+
 			$userDir = '/'.$user.'/files';
 			$userRoot = OC_User::getHome($user);
 			$userDirectory = $userRoot . '/files';
diff --git a/lib/public/files/lock.php b/lib/public/files/lock.php
new file mode 100644
index 0000000000..fb1e4b9f1c
--- /dev/null
+++ b/lib/public/files/lock.php
@@ -0,0 +1,48 @@
+<?php
+/**
+ *
+ * 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/>.
+ *
+ */
+
+namespace OCP\Files;
+
+/**
+ * Class Lock
+ * @package OC\Files
+ */
+class Lock {
+	const READ = 1;
+	const WRITE = 2;
+
+	/** @var string $path Filename of the file as represented in storage */
+	protected $path;
+
+	public function __construct($path) {
+		$this->path = $path;
+	}
+
+	public function addLock($lockType) {
+		// This class is a stub/base for classes that implement locks
+		// We don't actually care what kind of lock we're queuing here
+	}
+
+	/**
+	 * Release locks on handles and files
+	 */
+	public function release($lockType) {
+		return true;
+	}
+
+}
\ No newline at end of file
diff --git a/lib/public/files/locknotacquiredexception.php b/lib/public/files/locknotacquiredexception.php
new file mode 100644
index 0000000000..9fb70e7cbe
--- /dev/null
+++ b/lib/public/files/locknotacquiredexception.php
@@ -0,0 +1,47 @@
+<?php
+/**
+ *
+ * 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/>.
+ *
+ */
+
+/**
+ * Public interface of ownCloud for apps to use.
+ * Files/LockNotAcquiredException class
+ */
+
+// use OCP namespace for all classes that are considered public.
+// This means that they should be used by apps instead of the internal ownCloud classes
+namespace OCP\Files;
+
+/**
+ * Exception for a file that is locked
+ */
+class LockNotAcquiredException extends \Exception {
+	/** @var string $path The path that could not be locked */
+	public $path;
+
+	/** @var integer $lockType The type of the lock that was attempted */
+	public $lockType;
+
+	public function __construct($path, $lockType, $code = 0, \Exception $previous = null) {
+		$message = \OC_L10N::get('core')->t('Could not obtain lock type %d on "%s".', array($lockType, $path));
+		parent::__construct($message, $code, $previous);
+	}
+
+	// custom string representation of object
+	public function __toString() {
+		return __CLASS__ . ": [{$this->code}]: {$this->message}\n";
+	}
+}
\ No newline at end of file
diff --git a/lib/public/files/storage.php b/lib/public/files/storage.php
index 323d20db56..758cbb2737 100644
--- a/lib/public/files/storage.php
+++ b/lib/public/files/storage.php
@@ -35,6 +35,7 @@ namespace OCP\Files;
  * All paths passed to the storage are relative to the storage and should NOT have a leading slash.
  */
 interface Storage {
+
 	/**
 	 * $parameters is a free form array with the configuration options needed to construct the storage
 	 *