1 files changed, 100 insertions, 0 deletions
diff --git a/lib/classes/FileLock.class.php b/lib/classes/FileLock.class.php
new file mode 100644
index 0000000..cf6c00a
--- /dev/null
+++ b/lib/classes/FileLock.class.php
@@ -0,0 +1,100 @@
+<?php
+/**
+ * file_lock.php
+ * Simple lock mechanism on a file basis.
+ *
+ * With the help of this class you can manage persistent locks. Locks are
+ * stored in files and potential additional data is stored as json.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * @author    Jan-Hendrik Willms <tleilax+studip@gmail.com>
+ * @copyright 2013 Stud.IP Core-Group
+ * @license   http://www.gnu.org/licenses/gpl-2.0.html GPL version 2
+ * @category  Stud.IP
+ * @since     2.4
+ */
+
+class FileLock
+{
+    protected static $directory = '';
+
+    /**
+     * Sets a new base path for the locks.
+     *
+     * @param String $directory
+     * @throws RuntimeException if provided directory is either not existant
+     *         or is not a directory or is not writable.
+     */
+    public static function setDirectory($directory)
+    {
+        if (!file_exists($directory) || !is_dir($directory) || !is_writable($directory)) {
+            throw new RuntimeException('Passed directory is not an actual directory or is not writable.');
+        }
+        self::$directory = rtrim($directory, '/') . '/';
+    }
+
+    protected $filename;
+
+    /**
+     * Constructs a new lock object with the provided id.
+     *
+     * @param String $id Identifier of the lock
+     */
+    public function __construct($id)
+    {
+        $this->filename = self::$directory . '.' . $id . '.json';
+    }
+    
+    /**
+     * Returns the filename of the lock.
+     *
+     * @return String Filename of the lock
+     */
+    public function getFilename()
+    {
+        return $this->filename;
+    }
+    
+    /**
+     * Establish or renew the current lock. Provided lock information will
+     * be stored with the lock.
+     *
+     * @param Array $data Additional information to bestore with the lock
+     */
+    public function lock($data = [])
+    {
+        $data['timestamp'] = time();
+        file_put_contents($this->filename, json_encode($data));
+    }
+
+    /**
+     * Tests whether the lock is in use. Returns lock information in
+     * $lock_data.
+     *
+     * @param mixed $lock_data Information stored in lock
+     * @return bool Indicates whether the lock is active or not
+     */
+    public function isLocked(&$lock_data = null)
+    {
+        if (!file_exists($this->filename)) {
+            return false;
+        }
+
+        $lock_data = json_decode(file_get_contents($this->filename), true);
+        return true;
+    }
+
+    /**
+     * Releases a previously obtained lock
+     */
+    public function release()
+    {
+        if (file_exists($this->filename)) {
+            unlink($this->filename);
+        }
+    }
+}
+\ No newline at end of file